11 research outputs found
The effect of specimen thickness on the shock propagation along the in-fibre direction of an aerospace-grade CFRP laminate
No full textIn-fibre measurements of the Hugoniot have been carried out on a carbon fibre-reinforced polymer composite. For this material, we have shown at high shock stresses, a two component wave was formed consisting of a fast moving ramped portion and a slower moving shock wave. Changing the thickness of test specimen for a given shock stress resulted in a change in the magnitude and duration of the ramped portion of the wave front. As the shock stress imparted to the target was reduced, or the thickness of the target was increased, the steep shock wave in the rear surface gauge was no longer apparent. Instead a relatively slow rising wave was measured. Consequently, to establish a Hugoniot at lower shock stress levels, relatively thin specimens of target material are required
Stability of Cs-Ionsiv in Portland cement blends for radioactive waste disposal
No full textThe suitability of Portland cement blends for encapsulation of Cs-Ionsiv in a monolithic wasteform was investigated. No evidence of reaction or dissolution of the Cs-Ionsiv in the cementitious environment was found by scanning electron microscopy and X-ray diffraction. However, a small fraction (≤1.6 wt%) of the Cs inventory was released from the encapsulated Ionsiv during leaching experiments carried out on hydrated samples. Cs release was enhanced by exchange of K and Na present in the cementitious pore water. Cement systems lower in K and Na, such as slag based blends, showed lower Cs release than the fly ash based analogues. © 2010 Materials Research Society
States, firms, and oil : British policy, 1939-54
No full textNew
evidence
from the records of the Anglo-Iranian Oil Company (now British
Petroleum) and Shell for the period,
1939-45 supplements accounts of British
oil relations
based on state archives. This historical account demonstrates the continuity between the
interwar industry cartel and the Allied
wartime collaboration orchestrated through industry
committees. The
companies made use of their quasi-official position to manage crisis of
prewar arrangements aggravated by the war which presaged the rapid expansion of
postwar Middle East production. The companies then shaped the Anglo-American Oil
Agreements of
1944
and 1945, establishing a
basis for
remaking their position
in the
Middle East, expanding the web of
interfirm
relations. The nationalisation of
Anglo-
Iranian in 1951 threatened the web and the companies were able to embargo nationalised
Iranian oil and thus bankrupt the state. This society of oil majors was constituted by
shared
understandings and interests cultivated by the companies.
Structures of private governance may be quite significant factors for
states allied to them.
The United Kingdom
was more closely tied into the system of private governance that
prevailed in international oil
in the middle
decades of the century than was the United
States and consequently was able to call on more resources to resist
United States
initiatives during this period. British influence persisted in the oil
issue-area, in
spite of
greater
United States resources overall, because of this close working relationship
between state and companies. Close examination of the relationship reveals the extent of
penetration by the companies into both the decision-malting and implementation of
foreign
relations. The `national' interest was thus articulated through an interplay of
Governmental
and corporate agendas, and this supports a general argument that `national' power
is not
exercised solely
by the state, but by the state in
cooperation with other powerful social
institutions. Non-state actors and their archives may enrich the study of foreign relations
An Evaluation of Single Phase Ceramic Formulations for Plutonium Disposition
No full textAbstractTailored ceramics are promising potential hosts for the immobilization of actinides [1]. In this study the potential of a range of different ceramic systems were investigated for the incorporation of waste plutonium, using Ce as a Pu surrogate. Durable actinide containing minerals exist in nature and provided excellent target phases for the titanate, zirconate, silicate and phosphate based formulations examined here [2]. The Ce single phase solid solution limits for each system were established and the processing parameters required to produce high quality ceramic specimens were optimised. Importantly, this was achieved within the constraints of a generic processing route suitable for fabrication of Pu bearing samples.</jats:p
Proper Ferroelectricity in the Dion?Jacobson Material CsBi2Ti2NbO10: Experiment and Theory
No full textA diverse range of materials and properties are exhibited by layered perovskites. We report on the synthesis, characterization, and computational investigation of a new ferroelectric?CsBi2Ti2NbO10, an n = 3 member of the Dion?Jacobson (DJ) family. Structural studies using variable temperature neutron powder diffraction indicate that a combination of octahedral rotations and polar displacements result in the polar structure. Density functional theory calculations reveal that the wider perovskite blocks in CsBi2Ti2NbO0 stabilize proper ferroelectricity, in contrast to the hybrid-improper ferroelectricity reported for all other DJ phases. Our results raise the possibility of a new class of proper ferroelectric materials analogous to the well-known Aurivillius phases
Proper Ferroelectricity in the Dion–Jacobson Material CsBi<sub>2</sub>Ti<sub>2</sub>NbO<sub>10</sub>: Experiment and Theory
No full textA diverse range of materials and
properties are exhibited by layered
perovskites. We report on the synthesis, characterization, and computational
investigation of a new ferroelectricCsBi<sub>2</sub>Ti<sub>2</sub>NbO<sub>10</sub>an <i>n</i> = 3 member of
the Dion–Jacobson (DJ) family. Structural studies using variable-temperature
neutron powder diffraction indicate that a combination of octahedral
rotations and polar displacements result in the polar structure. Density
functional theory calculations reveal that the wider perovskite blocks
in CsBi<sub>2</sub>Ti<sub>2</sub>NbO<sub>0</sub> stabilize proper
ferroelectricity, in contrast to the hybrid-improper ferroelectricity
reported for all other DJ phases. Our results raise the possibility
of a new class of proper ferroelectric materials analogous to the
well-known Aurivillius phases
Lake surface temperature [in "State of the climate in 2015"]
No full textSxviAUGUST 2016|ABSTRACT—J. BLUNDEN AND D. S. ARNDTIn 2015, the dominant greenhouse gases released into Earth’s atmosphere—carbon dioxide, methane, and nitrous oxide—all continued to reach new high levels. At Mauna Loa, Hawaii, the annual CO2 concentration increased by a record 3.1 ppm, exceeding 400 ppm for the first time on record. The 2015 global CO2 average neared this threshold, at 399.4 ppm. Additionally, one of the strongest El Niño events since at least 1950 developed in spring 2015 and continued to evolve through the year. The phenomenon was far reaching, impacting many regions across the globe and affecting most aspects of the climate system.Owing to the combination of El Niño and a long-term up-ward trend, Earth observed record warmth for the second con-secutive year, with the 2015 annual global surface temperature surpassing the previous record by more than 0.1°C and exceed-ing the average for the mid- to late 19th century—commonly considered representative of preindustrial conditions—by more than 1°C for the first time. Above Earth’s surface, lower troposphere temperatures were near-record high.Across land surfaces, record to near-record warmth was reported across every inhabited continent. Twelve countries, including Russia and China, reported record high annual tem-peratures. In June, one of the most severe heat waves since 1980 affected Karachi, Pakistan, claiming over 1000 lives. On 27 October, Vredendal, South Africa, reached 48.4°C, a new global high temperature record for this month. In the Arctic, the 2015 land surface temperature was 1.2°C above the 1981–2010 average, tying 2007 and 2011 for the high-est annual temperature and representing a 2.8°C increase since the record began in 1900. Increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 25 February 2015, the lowest maximum sea ice extent in the 37-year satel-lite record was observed, 7% below the 1981–2010 average. Mean sea surface temperatures across the Arctic Ocean dur-ing August in ice-free regions, representative of Arctic Ocean summer anomalies, ranged from ~0°C to 8°C above average. As a consequence of sea ice retreat and warming oceans, vast walrus herds in the Pacific Arctic are hauling out on land rather than on sea ice, raising concern about the energetics of females and young animals. Increasing temperatures in the Barents Sea are linked to a community-wide shift in fish populations: boreal communities are now farther north, and long-standing Arctic species have been almost pushed out of the area.Above average sea surface temperatures are not confined to the Arctic. Sea surface temperature for 2015 was record high at the global scale; however, the North Atlantic southeast of Greenland remained colder than average and colder than 2014. Global annual ocean heat content and mean sea level also reached new record highs. The Greenland Ice Sheet, with the capacity to contribute ~7 m to sea level rise, experienced melting over more than 50% of its surface for the first time since the record melt of 2012.Other aspects of the cryosphere were remarkable. Alpine glacier retreat continued, and preliminary data indicate that 2015 is the 36th consecutive year of negative annual mass balance. Across the Northern Hemisphere, late-spring snow cover extent continued its trend of decline, with June the sec-ond lowest in the 49-year satellite record. Below the surface, record high temperatures at 20-m depth were measured at all permafrost observatories on the North Slope of Alaska, increasing by up to 0.66°C decade–1 since 2000. In the Antarctic, surface pressure and temperatures were lower than the 1981–2010 average for most of the year, consis-tent with the primarily positive southern annular mode, which saw a record high index value of +4.92 in February. Antarctic sea ice extent and area had large intra-annual variability, with a shift from record high levels in May to record low levels in August. Springtime ozone depletion resulted in one of the largest and most persistent Antarctic ozone holes observed since the 1990s.Closer to the equator, 101 named tropical storms were observed in 2015, well above the 1981–2010 average of 82. The eastern/central Pacific had 26 named storms, the most since 1992. The western north Pacific and north and south Indian Ocean basins also saw high activity. Globally, eight tropical cyclones reached the Saffir–Simpson Category 5 intensity level.Overlaying a general increase in the hydrologic cycle, the strong El Niño enhanced precipitation variability around the world. An above-normal rainy season led to major floods in Paraguay, Bolivia, and southern Brazil. In May, the United States recorded its all-time wettest month in its 121-year national record. Denmark and Norway reported their second and third wettest year on record, respectively, but globally soil moisture was below average, terrestrial groundwater storage was the lowest in the 14-year record, and areas in “severe” drought rose from 8% in 2014 to 14% in 2015. Drought conditions prevailed across many Caribbean island nations, Colombia, Venezuela, and northeast Brazil for most of the year. Several South Pacific countries also experienced drought. Lack of rainfall across Ethiopia led to its worst drought in decades and affected millions of people, while prolonged drought in South Africa severely affected agricultural production. Indian summer monsoon rainfall was just 86% of average. Extremely dry conditions in Indonesia resulted in intense and widespread fires during August–November that produced abundant car-bonaceous aerosols, carbon monoxide, and ozone. Overall, emissions from tropical Asian biomass burning in 2015 were almost three times the 2001–14 average
