bluuebunny/crossref_metadata_2025 huggingface dataset:
Operation of a utility boiler on coal-oil mixture
Authors: Whaley H , Whalen P J , Davies F W
Published: July 2017

A cooperative project to determine the feasibility of burning coal-oil mixtures in a small utility boiler has been undertaken by the New Brunswick Electric Power Commission and the Department of Energy, Mines and Resources e Canada. This paper describes the
boiler operation during two phases 1977/78 and 1978/79. In the initial phase no major equipment modifications . were undertaken except the addition of the coal-oil mixing system. However, in the later phase, coal beneficiation by spherical agglomeration was incorporated into the COM preparation to
reduce environmental emissions of fly ash and sulfur dioxide and to minimize the burner tip and equipment erosion previously experienced and directly attributable to the coal ash in the fuel. The environmental emissions of fly ash and sulfur dioxide as well as the operating efficiencies are given
for baseline oil firing and for a 10-15 wt% COM both with and without coal beneficiation.
Performance of retrofit flame retention heads in domestic oil furnaces
Authors: Hayden A C S , Braaten R
Published: July 2017

Existing oil-fired domestic heating systems in Canada offer the potential for significant fuel savings by improving burner performance and reducing the degree of oversizing of the furnace/boiler. These actions can be achieved by retrofitting the existing oil
burner with a (CSA-approved) retention head kit, coupled with downsizing of the firing rate. Temperatures measured in two warm-air furnaces, one with a stainless steel combustion chamber and the other with a ceramic combustion chamber indicate no problems should be encountered due to overheating of
the combustion chamber nor primary heat exchanger, provided the stainless steel chamber is lined with ceramic fibre and the maximum allowable firing rate is reduced one size. Both of these requirements now exist in the CSA code for retrofitting retention heads.
Utilization of a beneficiated coal-oil mixture in a small utility boiler
Authors: Whaley H , Whalen P J , Davies F W
Published: July 2017

The New Brunswick Electric Power Commission and the Department of Energy, Mines and Resources Canada have undertaken a cooperative demonstration project to evaluate the feasibility of burning coal-oil mixtures in a small utility boiler.//This paper briefly
describes the first two phases of the project which were conducted in 1977/78 and 1978/79 and some of the current activities of the 1979/80 third phase. /In the first phase of the project no major equipment modifications were undertaken except the in-line addition of a system for mixing pulverized
coal in residual fuel oil. In the second phase, coal beneficiation by spherical agglomeration was incorporated into the COM preparation to reduce environmental emissions of fly ash and sulphur dioxide and the minimize burner tip and equipment wear which is directly attributable to the coal ash in
the fuel. The current third phase of the project has incorporated modifications to improve the performance of the agglomeration process and the reliability of CON handling equipment./To date, COM's having a coal content ùp to 20% by weight have been utilized and combustion trials are
planned with 40% CON in March 1980.
Some effects of catalyst composition on deactivation and coke formation when hydrocracking Athabasca bitumen
Authors: Ternan M , Kriz J F
Published: July 2017

Catalyst coke formation, metals accumulation and rates of hydrocracking catalyst deactivation have been measured. The ranking of hydrocracking catalysts with different chemical compositions was considered in terms of electronic concepts. Initial catalyst
deactivation rates for times on stream less than 50 hours were related to the initial catalyst coke content. For longer times on stream all catalysts regardless of their chemical composition had similar deactivation rates. A simple model of catalyst decay was developed and applied to the data. The
results indicated that catalyst chemical composition does not influence the long term deactivation rate, although it has a strong influence on most rates of reaction. An., alternative strategy for more gradual deactivation is proposed.
A consideration of coal slurry transportation for Canada
Authors: Skubnik M , Whalley B J P
Published: July 2017

Despite the use of a modern transportation system, the movement of more than one-half of the coal mined in Canada an average distance of 1100 km to the west coast remains a major expense. During the next two decades the volume of coal exports is expected to
increase fourfold. Inflation and increasing energy costs will likely cause conventional transportation costs to account for an increasingly large proportion of the delivered price of coal and endanger coal sales. In Canada, with a view to alternate modes of transportation, slurry pipeline technology
has been studied for 20 years and has been considered from time to time for transporting coal to the west coast for export, to energy deficient Ontario for power production and also into the Western Canadian oil fields for use in extraction and upgrading plants. Water is generally assumed to be a
vehicle for coal slurry pipelines; there is now an increasing interest in using alternative liquid fuels as the carrier. Water, crude oil and methanol modes of coal pipelining are compared and their implications discussed in terms of their availability, coal-liquid interaction, coal liquid
separation, and system economics.
Coal gasification combined cycles for electricity production
Authors: Brown T D
Published: July 2017

This introductory review summarizes a series of specific areas of technology which must contribute to the development of a coal gasification-combined cycle power plant. The optional combinations of the gas and steam turbines are each seen to pose different
technical problems. The paramount importance of the development of a high temperature (>1200°C) turbine inlet temperature and the subsidiary role of high temperature gas cleaning and water requirements are discussed; the prospective reliability of gasifier/ boiler couplings are
largely unknown. The cost of electricity from the combined-cycle process has been shown to be most attractive in regions of high cost coal. It is considered likely that combined cycle power production will be implemented where conditions of high coal cost, low water availability and strict emission
regulations coexist. The commentary is framed in the perspective of Canadian coal resources, however most comments apply to all coal gasification combined cycle power plants and examples are drawn from all sources
Description of the mark ii atmospheric fluidized bed combustor at the Canadian Combustion Research Laboratory
Authors: Hector D R , Desai D L , Friedrich F D , Anthony E J
Published: July 2017

The facilities for fluidized bed research at the Canadian Combustion Research Laboratory at CANMET's Bells Corners Complex near Ottawa have been improved recently by the development of a pilot-scale combustor suitable for testing a wide variety of solid fuels.
The major features of the new facility are a 380 mm x 400 mm Atmospheric Fluidized Bed Combustor (AFBC) with variable in-bed cooling, capability of feeding a variety of fuel sizes both in-bed and over-bed, sulphur sorbent injection, and fines recycle. The combustor and its auxiliary equipment are
described in detail and CCRL's current capabilities for AFBC research are outlined. The facility was brought to the point of operability in March 1981, although elements of the gas clean-up system are not yet in service. Preliminary testing using Klimax lignite from Saskatchewan demonstrated
satisfactory performance of the combustor. The R & D program planned for the next few years will expand on previous research conducted on a smaller AFBC at CCRL, and is designed to provide information necessary for the design of full-scale fludized bed combustion.
Emissions from domestic wood burning systems problems and potential solutions
Authors: Hayden A C S , Braaten R W
Published: July 2017

Air pollution from woodfired appliances has become a major concern of regulatory authorities in many areas, and has caused some to seriously consider banning their use in certain critical regions. The emissions are due to incomplete combustion, resulting from
design shortfalls in present appliances. Emissions of concern are carbon monoxide and unburned hydrocarbons, including what are known as POM's (polycyclic organic matter), where known carcinogens have been identified as prime constituents. The levels and problems which can occur from these emissions
are discussed, particularly when compared with alternative energy sources. Performance of some new combustion designs which offer potential to reduce these emissions considerably is presented. Any technique which succeeds in reducing these emissions will have two additional benefits: efficiency will
be increased and the propensity to produce creosote will be decreased. Unless the industry can develop these or other advanced designs in the near future, severe limits are likely to be placed on its growth, due to the potential air pollution problem.
Canadian investigations into the determinations of the reduction disintegration of iron ore materials and the free swelling of iron oxide pellets
Authors: Price J T
Published: July 2017

Over the past decade CANMET has established facilities to conduct physical testing of coke and iron ore materials under simulated blast furnace conditions. The success of the CANMET program in testing iron materials according to ISO TC 102 proposed methods has
encouraged two Canadian steel companies and one iron ore company to develop similar facilities. This report presents results from three Canadian Laboratories participating in International Round Robin testing of the free-swelling and reduction disintegration (RDI) of iron ore materials. Standard
deviations and precisions of the RDI test vary with the degree of ore degradation. Canadian results also indicate that RDI indices of iron oxide pellets and sinters deteriorate severely if small amounts of H2 are included in the reducing gas. Small changes in temperature near 500 °C had little
effect on the RDI indices of one poor quality iron ore pellet.
Combustion performance of blends of a reactive and an unreactive Canadian coal
Authors: Lee G K , Whaley H
Published: July 2017

Pilot-scale boiler trials were conducted to study the combustion, deposition and ash emission characteristics of blends of two western Canadian bituminous coals. Both coals contained less than 0.5% sulphur, but one was unoxidized, high volatile and highly
reactive, whereas the other was oxidized, low-volatile and relatively unreactive. The blending trials, which were designed to establish whether the combustion efficiency of the low-reactivity coal could be enhanced by blending with a more reactive coal, showed that the carbon carry-over and fly ash
loadings were directly dependent on the proportion of unreactive coal in each blend. As predicted the slagging and fouling propensity of all coal blends was low as was the potential for low temperature corrosion. Emission levels of SOx and NO x using opposed tangential burners were within current
North American guidelines for new plants.
Oil to coal conversion: the Chatham coal-water-mixture trials
Authors: Rankin D M , Read P J , Whaley H
Published: July 2017

Interest in coal-liquid mixtures as potential oil replacement fuels has been continuing in Canada since the early seventies. The initial motives for this interest were the rapidly rising cost of oil coupled with an insecurity of supply. The possibility of the
recurrence of extreme energy price and supply fluctuations is the reason for continued efforts in the development of coal-liquid-mixture technology. A description is given of the three phases of an early program undertaken at Chatham, New Brunswick in which coal-oil mixtures were used in a small
utility boiler. Phase 1 of this program showed that burner and equipment wear was a significant impediment to coal-oil mixture utilization. This led to the inclusion of an oil agglomeration coal beneficiation process being incorporated into the fuel preparation process as a means of reducing the
sulphur and abrasive ash content of the coal. The evolution of this early program into the present program of coal-water mixture preparation and combustion testing for utility applications is described in detail. 1
Overview of combustion research at CANMET
Authors: Lee G K
Published: July 2017

Current combustion research activities at the Canada Centre for Mineral and Energy Technology (CANMET) reflect the increasingly important role that energy conservation and alternatives to oil are expected to make in meeting our future energy requirements and in
reducing our dependence on foreign oil. Widespread use of substitutes for oil, particularly low grade resources such as coal and waste wood will, however, be heavily dependent on the ability of conventional and emerging combustion systems to cope with the disruptive conflicts caused by variations in
fuel quality, on requirements for better equipment availability and on the implementation of progressively more stringent environmental constraints. To minimize these conflicts, Energy, Mines and Resources Canada has embarked on a systematic sequence of research, development and demonstration-scale
(R, D and D) initiatives to stimulate the utiization and competitiveness of thermal coal in both domestic and export markets through a number of complementary in-house projects and external contracts, considered to have short- to intermediate-term benefits to industry and society. Many of the
in-house projects are funded in part by industry, whereas the external contracts are either fully funded (100% government funding) or jointly funded (50% government - 50% project proposer). External contracts and shared-cost projects are an important adjunct to the CANMET in-house effort
on combustion because research data can be more effectively transferred to industry and because the commercialization of novel combustion systems can be accelerated significantly.
A novel method for separation and identification of sulphur compounds in naphtha (30-200 ° c) and middle distillate (200-350 ° c) fractions of Lloydminster heavy oil by gas chromatography/mass spectrometry
Authors: Poirier M A , Smiley G T
Published: July 2017

A procedure for the separation and identification of organic sulphur compounds from petroleum and related fractions has been investigated and applied to the naphtha (30-200 °C) and a middle distillate fraction (200-350 ° C) of a feed and a processed
Lloydminster heavy oil. The method permits the concentration of the sulphur compounds from a distillate fraction, although some aromatic hydrocarbons have been found in the sulphur compound concentrate. The separation method was developed using a mixture of model aliphatic and aromatic sulphides,
thiophenes and aromatic hydrocarbons of varied structure covering the investigated boiling range. The procedure employs liquid-solid chromatography, gas chromatography and mass spectrometry. The sulphur compounds were concentrated in the aromatic fraction by chromatography on a silica gel column.
The sulphur compound concentrate (sulphides and thiophenes) was obtained by chromatography of the aromatic fraction on a dual packed silica gel/alumina column using a pentane/ethyl acetate (95:5) mixture as eluent. The concentrate was then analyzed by gas chromatography/mass spectrometry. Twenty
eight sulphur compounds were tentatively identified by mass spectrometry.
Computer aided derating assessment of oil-designed wall-fired utility boilers using coal-water slurry fuel
Authors: Griffin S R , Shaw W A , Whaley H
Published: July 2017

In order to assess the potential derating of oil-designed utility boilers when using coal-water mixtures fuels, CANMET has issued two contracts to Babcock & Wilcox Canada. The first contract, described in this report, was to make a computer aided
assessment of the derating of two typical Eastern Canadian front-wall fired boilers representing the extremes of operating practice for this type of boiler. The derating was to be assessed for two boiler sizes 60 and 200 MW(e), coal-water mixtures of high ash and low ash composition and also for
pulverized coal firing. A similar contract describing the potential derating of tangentiallyfired boilers typical of Eastern Canada has been completed and will be reported in the near future.
Conversion of natural gas to liquid fuels
Authors: Allenger V M
Published: July 2017

A brief review of existing technology for the conversion of natural d' gas to liquids is presented. A large incentive exists to carry out this conversion in one step to improve thermal efficiency and to reduce initial b capital equipment investment. Pyrolysis
studies have been carried out in a tubular flow reactor of high purity alumina. Direct thermal decomposition of methane produced low liquid yields (0.02 g/L CH) at relatively high temperatures (900-1000 ° C). Recommendations are made for reactor design in which catalytic studies on
high-temperature methane conversion are to be carried out.
The control of Nox and Sox emissions from conventional pulverized coal flames: the Canadian program
Authors: Lee G K , Whaley H , Heap M P
Published: July 2017

Research work sponsored under an International Energy Agency Agreement between Canada, Denmark and Sweden has shown that NO x and SOx emissions from pulverized coal flames can be reduced significantly by staged combustion concepts. During this project in which 45
coals were evaluated, it was determined that much of the fuel nitrogen in the volatile matter can be transformed to N2 instead of NO. The conversion of fuel nitrogen to NO was from 30% to 40 7 in conventional flames but only from 7% to 14% in staged flames. Nitrogen retained in the char
showed about 20% conversion to NO and appeared to be relatively independent of local oxygen concentration. Reductions in sulphur emissions of 50% by sorbent injection into tertiary combustion air were achievable with Ca/S ratios of 2/1. These research results are being incorporated into two
proposed field trials involving retrofits of staged combustion systems in a frontwallfired and a tangentiallyfired boiler.
The characterization of oxidized coal - a review
Authors: Andersen N E , Hamza H A
Published: July 2017

The presence of oxidized coal causes substantive problems in the coal industry. It would be of benefit to producers and end-users alike if the existence and extent of oxidation could be easily and reliably determined. Many methods have been proposed;
unfortunately no completely acceptable method has yet been established. The extremely variable and complex nature of coal has been a major stumbling block in the development of a generally - applicable method of characterization. Most methods require comparison to results obtained on unoxidized
samples of the same coal, a process which is obviously not always feasible. Moreover, the absolute measurement of degree of oxidation is not an end in itself, but must be related to changes affecting coal processing and relative technological properties. This paper is an attempt to summarize methods
which have been used to detect and/or quantify the oxidation state of a coal. Attention is focussed on problems encountered and limitations of the data obtained. The reader is referred to the bibliography for detailed descriptions of the various methodologies.
Current coal-fired boiler technology in China
Authors: Lee G K , Lau I T
Published: July 2017

China, one of the world's largest energy producers, relied on coal for 70% of its primary energy demand in 1984. Coal production, which was centred around the rich deposits in the northern and northeastern provinces, reached almost 800 million tonnes and was
used primarily as boiler fuel. The widespread use of all ranks of coals in conventional equipment is being complemented by the development of large boilers to burn efficiently and cleanly coals with heating values below 12,6 NJ/kg. Pulverized-fired and fluidized-bed boilers rated at 850 and 150 t/h
of steam respectively are now being demonstrated on coals containing more than 607 ash. Foreign technology for pulverized-fired boilers up to 600 MWe, automated combustion controls and pollution abatement processes will be built under joint venture agreements. Combustion research facilities are
being expanded to support the forecast growth in coal consumption with increased emphasis on the utilization of low-grade coals.
Catalysts for hydroprocessing mixtures of heavy oil and coal
Authors: Monnier J , Kriz J F
Published: July 2017

Mixtures of one part coal and two parts residual oil from vacuum distillation of an Alberta heavy oil were hydroprocessed in a semi-continuous autoclave system with nickel, cobalt, molybdenum, tungsten and calcium catalysts. Low severity experimental conditions
were such that the hydroprocessing reactions proceeded at the threshold of coking. A constant flow of hydrogen at a pressure of 3.4 MPa (500 psig) was supplied to the reactor during these tests. The light hydrocarbons were collected from the exiting gases in a cold trap for elemental analysis and
simulated distillation. The heavier products were characterized by solvent extraction as oil, asphaltenes, preasphaltenes and THF insolubles. Catalysts were compared on the basis of conversion of THF insolubles, yields of oil, asphaltenes and preasphaltenes, and sulphur content of the distillates.
As expected, cobalt-molybdenum type catalysts performed well, enhancing oil production and conversion of THF insolubles. Petrographic analysis of the THF insolubles indicate that these catalysts also inhibited coke formation to a certain extent. The solubility data also indicate that a gain in
pentane-soluble oil is accompanied by a comparable loss in the THF insoluble portion of the product whereas other fractions change to a lesser extent.
Gas holdup in a tubular reactor at high pressure
Authors: de Bruijn T J W , Chase J D , Dawson W H
Published: July 2017

Gas holdup in a tubular reactor was measured at pressures from 5 to 14 MPa and temperatures of 300, 350 and 400°C using a differential pressure cell. The effects on gas holdup of gas density, temperature, liquid superficial velocity and gas superficial
velocity were studied using vacuum tower bottoms from a Venezuelan feedstock with 95.1 wt % +525°C material. Hydrogen was used at superficial gas velocities from 0.7 to 2.3 cm/s. The feed density at 300°C (5.57 MPa) and 400°C (13.9 MPa) was found to be 852 and 782 kg/m3 .
Increased gas density at a constant temperature of 300°C increased the gas holdup at all superficial gas velocities. Increasing the temperature from 300°C to 400°C did not affect the gas holdup for gas velocities up to 2.3 cm/s. Only at the highest gas rate of 2 cm/s at 300°C was
a higher gas holdup value obtained. An increase in the liquid flow rate from about 0.04 to 0.1 cm/s did not affect the gas holdup.
Time series analysis of gamma densitometry signals
Authors: Lipsett J J , Noble R D , Liu D D S
Published: July 2017

Single, narrow-beam densitometry has been developed as a method for determining the flow regime and void fraction for industrial liquidgas experiments at high pressures and temperatures in a vertical, thick-walled, steel vessel. To develop suitable techniques,
the experimental conditions were simulated using a transparent air/water column. In the transition region from bubbly to slug flow, a time sequence of four regimes, viz. annular flow, partially developed annular flow, coalescing bubble flow and bubbly flow were visually identified in a given cross
section. Gamma rays were used to interrogate a column diameter, and digital time series analysis methods were applied. Amplitude spectral densities were used to determine any periodicity in the gas phase flow. The average void fraction for periodic gas flows was obtained by analysis of probability
density distributions (PDD). The time sequence of the flow regimes was obtained from the signal magnitude of the diametral void fractions and the time spent in each regime was measured by the associated probability. The results compared well with those obtained from other methods. In the bubbly flow
region, the standard deviation of the PDD exceeded that expected for nuclear counting. This bubble noise was assessed with respect to bubble properties.
Developments in atomization and burner design for coal-water mixture combustion
Authors: Thambimuthu K V , Whaley H , Lee G K
Published: July 2017

Experimental data from coal-water mixture (CWM) spray atomization studies have been interpreted according to a new theory for the mechanism of atomization recently proposed in the literature. Measurements of combustion aerodynamics and ignition behaviour in
pilot-scale CWM flames were used to identify burner design and operating parameters critical to the, flame stability and burnout. For CWM atomization in two-fluid atomizers, it is proposed that the surface tension, coal particle size distribution and the aerodynamic shear force are controlling
parameters. CWM spray data correlated well with the Weber Number, and the-- performance of two-fluid atomizers was found to be dependent on the atomizer geometry and its operating flow regime. Burner design and operating parameters to optimize flow recirculation for convective heating, and to
maximize the residence time of the spray in the Internal Recirculation Zone were found to be critical for the stable combustion of CWM. Significant process parameters include the degree of combustion air preheat and swirl, the half angle and length to diameter ratio of the burner quarl and the spray
injection angle and momentum of the two-fluid atomizer. Many of the characteristics governing the atomization and combustion of CWM were found to be incompatible with the same parameters affecting oil combustion. This explains why the adaptation of oil-designed burners to CWM applications has proven
to be unsatisfactory.
La réglementation relative à la protection animale dans les animaleries du commerce
Authors: Mourey Eric Louis Gabriel , Beneult Bénédicte , Fabre Agnès
Published: July 2017

Depuis la signature par la France de la Convention du Conseil de l’Europe sur la protection des animaux de compagnie en 1996, de nombreux textes législatifs et réglementaires ont été élaborés sur cette thématique au plan national comme la loi du 6 janvier 1999 ou le décret du 28 août 2008. Ainsi, plusieurs décrets et arrêtés constituent un socle réglementaire sur ce sujet. La protection des animaux de compagnie dans les animaleries du commerce en fait partie. La réglementation s’appliquant à ces établissements définit les prescriptions à respecter pour d’une part assurer le bien-être des animaux et d’autre part promouvoir la responsabilisation des acheteurs. Des visites sanitaires devant être réalisées par des vétérinaires habilités sont également obligatoires dans ces structures. De nouvelles obligations applicables en 2016 ont modifié la définition de l’élevage de chiens et chats pour changer certaines pratiques de vente et limiter les abandons. Une question d’importance se pose : il reste à savoir si l’Union européenne décidera de prendre pleinement en compte la protection de ces animaux au même titre que celle des animaux de rente ou des animaux utilisés à des fins scientifiques ? Décidera-t-elle de légiférer sur ce sujet en vue d’une harmonisation des différentes réglementations existant dans les États membres.
Development of a quantitative method for ultrasonographic assessment of recurrent laryngeal neuropathy in horses
Authors: Vavasseur Lucille , Lechartier Antoine , Robert Céline , Mespoulhès-Rivière Céline
Published: July 2017

Mise au point d’une méthode quantitative d’évaluation échographique de l’hémiplégie laryngée chez le cheval.

Plus accessible sur le terrain, moins invasive et mieux corrélée à l’endoscopie à l’effort que l’endoscopie au repos, il ne manque à l’exploration échographique du larynx par voie externe que des critères échographiques de suspicion objectifs pour en faire un outil clé du dépistage de l’hémiplégie laryngée chez le cheval. L’objectif de cette étude est de définir un paramètre échographique combinant une bonne concordance inter-échographistes et une bonne aptitude à discriminer les chevaux sains des chevaux présentant un défaut d’abduction du cartilage aryténoïde gauche à l’effort. La moyenne, sur trois images acquises en vue transversale, du ratio entre l’échogénicité moyenne d’un disque de 1130 pixels placé dans le muscle crico-aryténoïdien latéral et celle d’un disque de 1130 pixels placé dans le muscle vocal est le paramètre garantissant la meilleure concordance inter-échographistes. Ce paramètre présente par ailleurs une très bonne corrélation avec l’examen endoscopique à l’effort, considéré comme le Gold Standard.
Prévention des infections nosocomiales chez les animaux de compagnie par la biosécurité dans les établissements de soins vétérinaires
Authors: Keck Nicolas , Bernard Fabrice
Published: July 2017

Probablement sous-estimées en médecine vétérinaire, les infections nosocomiales ont des conséquences sanitaires mais aussi économiques ; en outre elles peuvent ternir la réputation des établissements. Elles sont associées à des facteurs de risque variés, intéressant plusieurs aspects de la médecine vétérinaire. Elles peuvent être d’origine endogène ou exogène, et dues à des agents pathogènes ou opportunistes divers. La maîtrise des infections nosocomiales vise à interrompre la chaîne de transmission et à réduire la vulnérabilité de l’hôte. Elle repose sur une approche globale, intégrant l’ensemble de l’organisation de l’établissement vétérinaire. La maîtrise des risques d’infection d’origine exogène repose essentiellement sur l’isolement des animaux infectés ou colonisés, la gestion des flux, les pratiques d’asepsie adaptées et les mesures d’hygiène. Elle concerne également l’utilisation d’équipements adaptés afin de limiter les infections liées aux contaminants de l’environnement. Le contrôle de la qualité de l’environnement permet la surveillance de points critiques et la recherche des sources de contamination. Des procédures doivent décrire les règles de biosécurité dans l’établissement.
The effect of hydroxyl functional groups and molar mass on the viscosity of non-crystalline organic and organic–water particles
Authors: Grayson James W. , Evoy Erin , Song Mijung , Chu Yangxi , Maclean Adrian , Nguyen Allena , Upshur Mary Alice , Ebrahimi Marzieh , Chan Chak K. , Geiger Franz M. , Thomson Regan J. , Bertram Allan K.
Published: July 2017

Abstract. The viscosities of three polyols and three saccharides, all in the non-crystalline state, have been studied. Two of the polyols (2-methyl-1,4-butanediol and 1,2,3-butanetriol) were studied under dry conditions, the third (1,2,3,4-butanetetrol) was studied as a function of relative humidity (RH), including under dry conditions, and the saccharides (glucose, raffinose, and maltohexaose) were studied as a function of RH. The mean viscosities of the polyols under dry conditions range from 1.5  ×  10−1 to 3.7  ×  101 Pa s, with the highest viscosity being that of the tetrol. Using a combination of data determined experimentally here and literature data for alkanes, alcohols, and polyols with a C3 to C6 carbon backbone, we show (1) there is a near-linear relationship between log10 (viscosity) and the number of hydroxyl groups in the molecule, (2) that on average the addition of one OH group increases the viscosity by a factor of approximately 22 to 45, (3) the sensitivity of viscosity to the addition of one OH group is not a strong function of the number of OH functional groups already present in the molecule up to three OH groups, and (4) higher sensitivities are observed when the molecule has more than three OH groups. Viscosities reported here for 1,2,3,4-butanetetrol particles are lower than previously reported measurements using aerosol optical tweezers, and additional studies are required to resolve these discrepancies. For saccharide particles at 30 % RH, viscosity increases by approximately 2–5 orders of magnitude as molar mass increases from 180 to 342 g mol−1, and at 80 % RH, viscosity increases by approximately 4–5 orders of magnitude as molar mass increases from 180 to 991 g mol−1. These results suggest oligomerization of highly oxidized compounds in atmospheric secondary organic aerosol (SOA) could lead to large increases in viscosity, and may be at least partially responsible for the high viscosities observed in some SOA. Finally, two quantitative structure–property relationship models (Sastri and Rao, 1992; Marrero-Morejón and Pardillo-Fontdevila, 2000) were used to predict the viscosity of alkanes, alcohols, and polyols with a C3–C6 carbon backbone. Both models show reasonably good agreement with measured viscosities for the alkanes, alcohols, and polyols studied here except for the case of a hexol, the viscosity of which is underpredicted by 1–3 orders of magnitude by each of the models.
Exploring gravity wave characteristics in 3-D using a novel S-transform technique: AIRS/Aqua measurements over the Southern Andes and Drake Passage
Authors: Wright Corwin J. , Hindley Neil P. , Hoffmann Lars , Alexander M. Joan , Mitchell Nicholas J.
Published: July 2017

Abstract. Gravity waves (GWs) transport momentum and energy in the atmosphere, exerting a profound influence on the global circulation. Accurately measuring them is thus vital both for understanding the atmosphere and for developing the next generation of weather forecasting and climate prediction models. However, it has proven very difficult to measure the full set of GW parameters from satellite measurements, which are the only suitable observations with global coverage. This is particularly critical at latitudes close to 60° S, where climate models significantly under-represent wave momentum fluxes. Here, we present a novel fully 3-D method for detecting and characterising GWs in the stratosphere. This method is based around a 3-D Stockwell transform, and can be applied retrospectively to existing observed data. This is the first scientific use of this spectral analysis technique. We apply our method to high-resolution 3-D atmospheric temperature data from AIRS/Aqua over the altitude range 20–60 km. Our method allows us to determine a wide range of parameters for each wave detected. These include amplitude, propagation direction, horizontal/vertical wavelength, height/direction-resolved momentum fluxes (MFs), and phase and group velocity vectors. The latter three have not previously been measured from an individual satellite instrument. We demonstrate this method over the region around the Southern Andes and Antarctic Peninsula, the largest known sources of GW MFs near the 60° S belt. Our analyses reveal the presence of strongly intermittent highly directionally focused GWs with very high momentum fluxes (∼ 80–100 mPa or more at 30 km altitude). These waves are closely associated with the mountains rather than the open ocean of the Drake Passage. Measured fluxes are directed orthogonal to both mountain ranges, consistent with an orographic source mechanism, and are largest in winter. Further, our measurements of wave group velocity vectors show clear observational evidence that these waves are strongly focused into the polar night wind jet, and thus may contribute significantly to the missing momentum at these latitudes. These results demonstrate the capabilities of our new method, which provides a powerful tool for delivering the observations required for the next generation of weather and climate models.
A more representative “best representative value” for daily total column ozone reporting
Authors: Smedley Andrew R. D. , Rimmer John S. , Webb Ann R.
Published: July 2017

Abstract. Long-term trends of total column ozone, assessments of stratospheric ozone recovery and satellite validation are underpinned by a reliance on daily “best representative values” from Brewer spectrophotometers and other ground-based ozone instruments. In turn reporting of these daily total column ozone values to the World Ozone and Ultraviolet Data Centre has traditionally been predicated upon a binomial choice between direct sun and zenith sky observations. For mid- and high-latitude monitoring sites impacted by cloud cover we discuss the potential deficiencies of this approach in terms of its rejection of otherwise valid observations and capability to evenly sample throughout the day. A new methodology is proposed that makes full use of all valid direct sun and zenith sky observations, accounting for unevenly spaced observations and their relative uncertainty, to calculate an improved estimate of the daily mean total column ozone. It is demonstrated that this method can increase the number of contributing observations by a factor of 2.5, increases the sampled time span, and reduces the spread of the representative time by half. No effect on longer-term trends is detected, though for the sample data analysed we observe a mean increase of 2.8 DU (0.82 %) w.r.t. the traditional direct sun vs zenith sky average choice. To complement the new calculation of a best representative value of total column ozone and separate its uncertainty from the spread of observations, we also propose reporting its standard error rather than the standard deviation, together with measures of the full range of values observed.
Variability of the Brunt-Väisälä frequency at the OH*-layer height
Authors: Wüst Sabine , Bittner Michael , Yee Jeng-Hwa , Mlynczak Martin G. , Russell III James M.
Published: July 2017

Abstract. In and near the Alpine region, the most dense sub-network of identical NDMC instruments (Network for the Detection of Mesospheric Change, http://wdc.dlr.de/ndmc) can be found: five stations are equipped with OH*-spectrometers which deliver a time series of mesopause temperature each cloudless or only partially cloudy night. These measurements are suitable for the derivation of the density of gravity wave potential energy—knowledge about the Brunt-Väisälä frequency provided. However, OH*-spectrometers do not deliver vertically-resolved temperature information, which are necessary for the calculation of the Brunt-Väisälä frequency. Co-located measurements or climatological values are needed. We use 14 years of satellite-based temperature data (TIMED-SABER, 2002–2015) to investigate the inter- and intra-annual variability of the Brunt-Väisälä frequency at the OH*-layer height between 43.93–48.09° N and 5.71–12.95° E and provide a climatology.
On the long-range offshore transport of organic carbon from the Canary Upwelling System to the open North Atlantic
Authors: Lovecchio Elisa , Gruber Nicolas , Münnich Matthias , Lachkar Zouhair
Published: July 2017

Abstract. A compilation of measurements of net community production (NCP) in the upper waters of the eastern subtropical North Atlantic had suggested net heterotrophic conditions, purportedly supported by the lateral export of organic carbon from the adjacent, highly productive Canary Upwelling System (CanUS). Here, we quantify and assess this lateral export using the Regional Ocean Modeling System (ROMS) coupled to a nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecosystem model. We employ a new Atlantic telescopic grid with a strong refinement towards the northwestern African shelf to combine an eddy-resolving resolution in the CanUS with a full Atlantic basin perspective. Our climatologically forced simulation reveals an intense offshore flux of organic carbon that transports about 19 Tg C yr−1 away from the nearshore 100 km over the whole CanUS, amounting to more than a third of the NCP in this region. The offshore transport extends beyond 1500 km into the subtropical North Atlantic, adding organic carbon along the way to the upper 100 m at rates of between 8 and 34 % of the alongshore average NCP as a function of offshore distance. Although the divergence of this lateral export of organic carbon enhances local respiration, the upper 100 m layer in our model remains net autotrophic in the entire eastern subtropical North Atlantic. However, the vertical export of this organic carbon and its subsequent remineralization at depth makes the vertically integrated NCP strongly negative throughout this region, with the exception of a narrow band along the northwestern African shelf. The magnitude and efficiency of the lateral export varies substantially between the different subregions. In particular, the central coast near Cape Blanc is particularly efficient in collecting organic carbon on the shelf and subsequently transporting it offshore. In this central subregion, the offshore transport adds as much organic carbon as nearly 60 % of the local NCP to the upper 100 m, giving rise to a sharp peak of offshore respiration that extends to the middle of the gyre. Our modeled offshore transport of organic carbon is likely a lower-bound estimate due to our lack of full consideration of the contribution of dissolved organic carbon and that of particulate organic carbon stemming from the resuspension of sediments. But even in the absence of these contributions, our results emphasize the fundamental role of the lateral redistribution of the organic carbon for the maintenance of the heterotrophic activity in the open sea.
TARANIS XGRE and IDEE detection capability of terrestrial gamma-ray flashes and associated electron beams
Authors: Sarria David , Lebrun Francois , Blelly Pierre-Louis , Chipaux Remi , Laurent Philippe , Sauvaud Jean-Andre , Prech Lubomir , Devoto Pierre , Pailot Damien , Baronick Jean-Pierre , Lindsey-Clark Miles
Published: July 2017

Abstract. With a launch expected in 2018, the TARANIS microsatellite is dedicated to the study of transient phenomena observed in association with thunderstorms. On board the spacecraft, XGRE and IDEE are two instruments dedicated to studying terrestrial gamma-ray flashes (TGFs) and associated terrestrial electron beams (TEBs). XGRE can detect electrons (energy range: 1 to 10 MeV) and X- and gamma-rays (energy range: 20 keV to 10 MeV) with a very high counting capability (about 10 million counts per second) and the ability to discriminate one type of particle from another. The IDEE instrument is focused on electrons in the 80 keV to 4 MeV energy range, with the ability to estimate their pitch angles. Monte Carlo simulations of the TARANIS instruments, using a preliminary model of the spacecraft, allow sensitive area estimates for both instruments. This leads to an averaged effective area of 425 cm2 for XGRE, used to detect X- and gamma-rays from TGFs, and the combination of XGRE and IDEE gives an average effective area of 255 cm2 which can be used to detect electrons/positrons from TEBs. We then compare these performances to RHESSI, AGILE and Fermi GBM, using data extracted from literature for the TGF case and with the help of Monte Carlo simulations of their mass models for the TEB case. Combining this data with the help of the MC-PEPTITA Monte Carlo simulations of TGF propagation in the atmosphere, we build a self-consistent model of the TGF and TEB detection rates of RHESSI, AGILE and Fermi. It can then be used to estimate that TARANIS should detect about 200 TGFs yr−1 and 25 TEBs yr−1.
A map of global peatland distribution created using machine
learning for use in terrestrial ecosystem and earth system models
Authors: Wu Yuanqiao , Chan Ed , Melton Joe R. , Verseghy Diana L.
Published: July 2017

Abstract. Peatlands store large amounts of soil carbon and constitute an important component of the global carbon cycle. Accurate information on the global extent and distribution of peatlands is presently lacking but it important for earth system models (ESMs) to be able to simulate the effects of climate change on the global carbon balance. The most comprehensive peatland map produced to date is a qualitative presence/absence product. Here, we present a spatially continuous global map of peatland fractional coverage using the extremely randomized tree machine learning method suitable for use as a prescribed geophysical field in an ESM. Inputs to our statistical model include spatially distributed climate data, soil data and topographical slopes. Available maps of peatland fractional coverage for Canada and West Siberia were used along with a proxy for non-peatland areas to train and test the statistical model. Regions where the peatland fraction is expected to be zero were estimated from a map of topsoil organic carbon content below a threshold value of 13 kg/m2. The modelled coverage of peatlands yields a root mean square error of 4 % and a coefficient of determination of 0.91 for the 10,978 tested 0.5 degree grid cells. We then generated a complete global peatland fractional coverage map. In comparison with earlier qualitative estimates, our global modelled peatland map is able to reproduce peatland distributions in places remote from the training areas and capture peatland hot spots in both boreal and tropical regions, as well as in the southern hemisphere. Additionally we demonstrate that our machine-learning method has greater skill than solely setting peatland areas based on histosols from a soil database.
A statistically based seasonal precipitation forecast model with automatic predictor selection and its application to central and south Asia
Authors: Gerlitz Lars , Vorogushyn Sergiy , Apel Heiko , Gafurov Abror , Unger-Shayesteh Katy , Merz Bruno
Published: July 2017

Abstract. The study presents a statistically based seasonal precipitation forecast model, which automatically identifies suitable predictors from globally gridded sea surface temperature (SST) and climate variables by means of an extensive data-mining procedure and explicitly avoids the utilization of typical large-scale climate indices. This leads to an enhanced flexibility of the model and enables its automatic calibration for any target area without any prior assumption concerning adequate predictor variables. Potential predictor variables are derived by means of a cell-wise correlation analysis of precipitation anomalies with gridded global climate variables under consideration of varying lead times. Significantly correlated grid cells are subsequently aggregated to predictor regions by means of a variability-based cluster analysis. Finally, for every month and lead time, an individual random-forest-based forecast model is constructed, by means of the preliminary generated predictor variables. Monthly predictions are aggregated to running 3-month periods in order to generate a seasonal precipitation forecast. The model is applied and evaluated for selected target regions in central and south Asia. Particularly for winter and spring in westerly-dominated central Asia, correlation coefficients between forecasted and observed precipitation reach values up to 0.48, although the variability of precipitation rates is strongly underestimated. Likewise, for the monsoonal precipitation amounts in the south Asian target area, correlations of up to 0.5 were detected. The skill of the model for the dry winter season over south Asia is found to be low. A sensitivity analysis with well-known climate indices, such as the El Niño– Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the East Atlantic (EA) pattern, reveals the major large-scale controlling mechanisms of the seasonal precipitation climate for each target area. For the central Asian target areas, both ENSO and NAO are identified as important controlling factors for precipitation totals during moist winter and spring seasons. Drought conditions are found to be triggered by a cold ENSO phase in combination with a positive state of NAO in northern central Asia, and by cold ENSO conditions in combination with a negative NAO phase in southern central Asia. For the monsoonal summer precipitation amounts over southern Asia, the model suggests a distinct negative response to El Niño events.