Analysis of ozone and nitric acid in spring and summer Arctic pollution using aircraft, ground-based, satellite observations and MOZART-4 model: source attribution and partitioning

In this paper, we analyze tropospheric O_3 together with HNO_3 during the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) program, combining observations and model results. Aircraft observations from the NASA ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) and NOAA ARCPAC (Aerosol, Radiation and Cloud Processes affecting Arctic Climate) campaigns during spring and summer of 2008 are used together with the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) to assist in the interpretation of the observations in terms of the source attribution and transport of O_3 and HNO_3 into the Arctic (north of 60° N). The MOZART-4 simulations reproduce the aircraft observations generally well (within 15%), but some discrepancies in the model are identified and discussed. The observed correlation of O_3 with HNO_3 is exploited to evaluate the MOZART-4 model performance for different air mass types (fresh plumes, free troposphere and stratospheric-contaminated air masses). Based on model simulations of O_3 and HNO_3 tagged by source type and region, we find that the anthropogenic pollution from the Northern Hemisphere is the dominant source of O3 and HNO3 in the Arctic at pressures greater than 400 hPa, and that the stratospheric influence is the principal contribution at pressures less 400 hPa. During the summer, intense Russian fire emissions contribute some amount to the tropospheric columns of both gases over the American sector of the Arctic. North American fire emissions (California and Canada) also show an important impact on tropospheric ozone in the Arctic boundary layer. Additional analysis of tropospheric O_3 measurements from ground-based FTIR and from the IASI satellite sounder made at the Eureka (Canada) and Thule (Greenland) polar sites during POLARCAT has been performed using the tagged contributions. It demonstrates the capability of these instruments for observing pollution at northern high latitudes. Differences between contributions from the sources to the tropospheric columns as measured by FTIR and IASI are discussed in terms of vertical sensitivity associated with these instruments. The first analysis of O_3 tropospheric columns observed by the IASI satellite instrument over the Arctic is also provided. Despite its limited vertical sensitivity in the lowermost atmospheric layers, we demonstrate that IASI is capable of detecting low-altitude pollution transported into the Arctic with some limitations

Reductive cleavage of P-4 by iron(I) centres: synthesis and structural characterisation of Fe-2(P-2)(2) complexes with two bridging P-2(2-) ligands

The selective transformation of white phosphorus with a beta-diketiminato iron(I) toluene complex under mild reaction conditions is reported which furnishes a new dinuclear iron(III) Fe-2(P-2)(2) complex with two bridging P-2(2-) ligands. Its reduction with potassium results in the formation of the first delocalised mixed-valent bis-diphosphido iron(II,III) complex which is isostructural with the neutral Fe2P4 precursor

Superimposing Planetary Gears as Variable Speed Drives for Rotating Equipment

LecturesThere are many high-power and high-speed pumps installed in power plants, oil & gas applications and in petrochemical industry consuming a considerable amount of energy. Significant interest exists within operators to improve their efficiency in order to save energy and operating cost. Most of the pumps are driven by electric motors and many of them are speed controlled since this is the most efficient method to adjust flow to process demand. Motor speed is controlled by frequency converters which are installed in-line and therefore they are of full scale and designed to full power. The complete power goes through the variable frequency drive and is subject to losses. A gear then is used in order to step-up motor speed to the requested speed level for the driven equipment. This paper describes a new method to improve efficiency of variable speed drives by power splitting. The main driver is a constant speed motor and its power is transmitted mechanically using the superior efficiency of an epicyclic gear. The gear is designed as revolving planetary gear where all three shafts can turn. One of those shafts is used as input; a second one as output and the third shaft is used for speed control. This principle allows using only a small percentage of rated power as control power to be generated by servo motors. Their frequency converters are placed in a sideline and hence their losses are subject to a small portion of rated power. Copyright© 2018 by Turbomachinery Laboratory, Texas A&M Engineering Experiment Station The control speed of the servo motors is superimposed in the revolving planetary gear to transform the constant speed of the main motor into a variable output speed for the driven equipment. A 7500 horse power prototype of an electrically controlled superimposing planetary gear (ESPG) was built and tested extensively. Efficiency measurements were done and could prove peak efficiency of 97 percent for the variable speed gear including lube oil pump, servo motors, frequency converter and transformer. This is up to 2.5 percent more than conventional variable speed systems with a full scale in-line variable frequency drive (VFD)

Superimposing Planetary Gears As Variable Speed Drives for Rotating Equipment

Lectur

libFIRM. A library for compiler optimization research implementing FIRM

This tutorial describes the Firm library and how to use it. The Firm library implements the Firm intermediate representation (ir) as described in UKA technical report 1999-14. In addition it supplies data structures to represent the type structure of the source program, a constant table and other modules necessary to represent a complete source program. Further it contains interfaces for construction of intermediate code from the front end and to access the ir. Several basic optimizations and analyses are supplied

Cacheoptimierung für Vererbungshierarchien

This thesis introduces an automatic compiler optimization that improves the cache performance of object oriented programs. A static analysis identifies potential hot spots in a program. It combines this information with an analysis of the type structure to select data types from which large data structures are constructed. These are subject to structure splitting and tzpe clustering. We compare the analysis results to profiling data. With both datasets we achieve up to 30% of speed up

Structure splitting and inheritance

The increasing gap between memory and processor performance drives the research for cache optimizations. Recently research concentrates on optimizing pointer based applications. Structure splitting is an important enabling transformation for optimizations that improve the layout of dynamic data structures. Previous work has shown the potential of structure splitting in runtime optimizations. This paper discusses issues of structure splitting applied to inheritance hierarchies of object oriented languages. Inheritance requires similar layout of compound types to simplify type casts. Structure splitting, in contrast, requires a layout that is tailored for a single type. Therefore compatibility between the split type and its super and sub-types is lost. This issue was not addressed by previous work. We explain several strategies to deal with this type compatibility issue and implement two as a compiler optimization. Our experiments show that a careful choice of the strategy is necessary, as they either increase the overhead for accessing cache-neutral data, or they can not achieve the full possible speed up for cache-critical data. Nevertheless, both approaches show considerable speed ups of our tests

Teilhabeplan für Menschen mit wesentlicher geistiger, körperlicher und mehrfacher Behinderung

TEILHABEPLAN FÜR MENSCHEN MIT WESENTLICHER GEISTIGER, KÖRPERLICHER UND MEHRFACHER BEHINDERUNG Teilhabeplan für Menschen mit wesentlicher geistiger, körperlicher und mehrfacher Behinderung / Lindenmaier, Julia [Bearb.] (Rights reserved) ( -