bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Formability Characteristics of the Weld Seam of Aluminum Steel Tailored Hybrid Blanks
Authors: Singar Ozan , Merklein Marion
Published: April 2013

Tailor Welded Blanks (TWB) are characterized by the fact that sheets with different material qualities and/or thicknesses are welded together before the forming process. The application of TWBs in the automobile industry brings several advantages, such as the reduction of car body weight and manufacturing costs, as well as the integration of several drawing parts into one part. Despite several established tailor welded blanks types, a new version has emerged: The Tailored Hybrid Blanks (THB). The current investigation focuses on tailored hybrid blanks joined by the CMT-welding technology. The main aim of this study is to specify the mechanical properties as well as the formability of Aluminum Steel Tailored Blanks. Steel (HX340LAD, 0.8 mm) sheets covered by different zinc coat thicknesses were combined with an aluminum alloy (AA6014-T4, 1.2 mm). In order to determine the material properties and to analyze the Heat Affected Zone (HAZ), microhardness measurements were taken transversal and longitudinal to the weld line. Results indicate a change of hardness and a very small HAZ. Tensile tests (perpendicular to weld line) and Nakajima tests with online deformation analyses show that the main formation takes place on the aluminum side.
Possibility of the Increase in Titanium Sheets' Drawability
Authors: Adamus Janina , Lacki Piotr
Published: April 2013

Forming of titanium sheets, especially titanium alloy sheets, is very difficult due to low drawability caused by a high ratio of the yield point to the tensile strength Re/Rm, usually more than 90%. Although drawability of titanium sheets can be enhanced by forming at elevated temperatures it is avoided due to the high costs and difficulties associated with the operation of the process. Therefore the authors have developed an unconventional stamping method allowing for forming of almost unworkable materials at ambient temperature, such as Ti6Al4V titanium alloy. The paper presents both numerical simulation and experimental results of the stamping process using a device specially designed for this purpose.
Effectiveness of Stamping Lubricants in Erichsen Test
Authors: Sener Bora , Kayali E.S.
Published: April 2013

In the present work, formability of ultra low carbon steel sheets (uncoated interstitial free and galvanized steel sheet) has been characterized and the effectiveness of dry and liquid lubricants on formability of these steel sheets was evaluated by using the standard Erichsen test. Primarily, some important mechanical properties of materials like strain hardening coefficient (n), normal anisotropy (r) were determined using the tensile test and formability of these steel sheets has been correlated with these mechanical properties. Then these steel sheets were subjected to the Erichsen test using four different lubricants. Teflon, PVC, Polyethylene films and mineral oil were used in the experiments. Finite element simulations were done using various friction coefficients. Erichsen tests were conducted at 1 kN blank holder force and 2.4 mm/min punch velocity. Values of the Erichsen index and punch force-displacement curves were determined for each lubricant. PVC film proved to be the most effective lubricant for both materials.
Integration of High Strength Steel (HSS) Elements in Automotive Industry
Authors: Cañibano Álvarez Esteban , Senovilla J.C. Merino , García J.Romo , Martín C. Maestro , López J. Sanz
Published: April 2013

High Strength Steels (HSS) and Advanced High Strength Steels (AHSS) are most commonly used nowadays in the automotive industry to achieve a weight reduction of the vehicle while assuring that all the safety requirements are fulfilled. These steels are characterized by very high ultimate stresses, reaching up to 1500MPa with yield strengths of up to 1000MPa. It is mainly because of these exceptional mechanical properties that it is becoming very usual to find these steels in sheets. This study presents a design methodology for integrated security sub-modules (constituting the suspension and steering modules) in the car manufacturing industry. The sub-modules are made up of a steel structure and different anchorage elements (rubber-metal or plastic-metal), which undergo separate surface treatments to avoid corrosion. Afterwards, the elements are traditionally joined by means of adhesives and screws. This process involves a great number of stages, low quality union methods and generation of corrosion areas that shorten its service life.
The first step in this study has been the construction of a metallic structure in high strength low alloy steel (HSLA), instead of in traditional steel, in order to benefit from its better safety performance and lower weight at affordable cost, moreover the industrial manufacturing process was simulate with F.E.M in order to reduce the cost in forming manufacturing process. The second step, the improvement proposed is based on the use of laser welding as joining method, a high quality way to reduce the number of anchorage points and to increase the resistance of the sub-module. The last step is the surface treatment on the integrated piece in order provide an unaltered coating. Overcoming the currently need of assembly processes, which usually causes serious damages on the protective surface, this treatment will suppose an increase in the response against corrosion of the pieces. Regarding this aspect, the development of an organic treatment with lower required temperatures (max. 100oC) has been proposed, paying particularly attention to the removal of pollutant elements (Cr (VI), Zn and Ni) involved in traditional methods.
This methodology provides automotive suppliers an additional added value and cost reduction, allowing them to increase their competitiveness in a sector that faces up to the transition from the traditional supply chain to a strategic value chain.
Simulation of a Thick Plate Forming Benchmark Using a Multi Scale Texture Evolution and Anisotropic Plasticity Model
Authors: Shore Diarmuid , Gawad Jerzy , Cooreman Steven , Lava Pascal , Debruyne Dimitri , Roose Dirk , Antonissen Joachim , van Bael Albert , van Houtte Paul
Published: April 2013

Thick plate and sheet materials are often characterised by an inhomogeneous distribution of properties such as yield strength and anisotropy throughout their thickness. Forming of these materials involves further heterogeneous evolution of these properties. A recently developed computational framework [1, now allows these heterogeneities to be modelled via a hierarchical multi-scale material modelling scheme: the evolution of texture and plastic anisotropy can be tracked and individually updated at every integration point in a finite element model, in a computationally efficient manner. In this paper we present the application of this multi-scale model to a benchmark forming simulation, the three point bending test of thick plate steels. A number of hot rolled high strength low alloy steels were considered, two of which are presented here. The results of the simulations are validated against experimental results. Comparison is made between computed and experimental deformed shapes and strain fields, using data acquired by digital image correlation. Predictions of heterogeneously evolved textures are compared with experimental macro-textures, acquired by XRD, at key locations in the final deformed samples. Such models for plate steel forming simulations that are able to provide accurate predictions of deformation textures and derived quantities in the entire volume of the material can be crucial to study further processing steps and properties of the final product.
Predicting Dimensional Accuracy of Laser Welded Aluminum Add-On Body Parts
Authors: Neugebauer Reimund , Bernhardi O.E. , Wahl Martin , Schulz Frank , Mauermann Reinhard , Schützle Wilhelm , Werner S.
Published: April 2013

Laser welding of complex aluminum add-on body parts such as vehicle doors, is a common joining technology in the automotive industry. Besides the many advantages (e.g. high processing speed) laser welding provides, temperature induced distortions are an important task to deal with. In the last twenty years, several simplified FE methods, which predict welding distortion (weld seams, spot welds) of large assemblies, were presented. In order to simulate the distortion of large car body components properly, realistic clamping conditions need to be considered [1, 2, 3]. Furthermore, the calibration process of simplified models has to be examined systematically, to find out their limits and achieve optimal simulation results [4]. In this paper, a new FE model is presented to predict distortion of laser welded structures, based on a shrinkage volume approach. Effective surface based clamping conditions (derived of the real clamping device) and effects of previous forming processes are considered. The simplified model was examined due to an extensive design of experiments. Not only simple, but even complex simulated specimens match with the experimental results very well.
The Downsizing Effects in EDM Drilling of Micro Holes
Authors: D'Urso Gianluca , Maccarini Giancarlo , Merla C.
Published: April 2013

The recent miniaturization trend in manufacturing, has enhanced the production of new and highly sophisticated systems in various industrial fields. In recent years, machining of the so called difficult to cut materials has become an important issue in several sectors. Micro Electrical Discharge Machining (micro-EDM) thanks to its contactless nature, is one of the most important technologies for the machining of this type of materials and it can be considered as one of the most promising manufacturing technologies for the fabrication of micro components. One of the most relevant applications of micro-EDM is micro-drilling. Micro holes in fact, are widely used for example in micro-electromechanical systems (MEMS), serving as channels or nozzles to connect two micro-features, and in micro-mechanical components. The present study is about micro drilling of metal plates by means of micro-EDM technology. In particular, the aim of this work is to investigate the effects of the downsizing of the micro holes diameter on the drilling performances. The influence of the reduction of the diameters in terms of both process performances (e.g., tool wear, taper rate, diametrical overcut) and general quality of the holes was investigated. Steel plates having thickness equal to 0.8 mm were taken into account. The drilling process was carried out using a micro-EDM machine Sarix SX 200 with carbide electrodes having diameter equal to 300, 200, 100 and 50 μm. Since the standard electrodes adopted in this study had a diameter equal to 300 μm, a wire EDM unit was used to obtain the other electrodes. The relationship between the process parameters considered the most significant and the final output, was studied. Furthermore, the geometrical and dimensional properties of the micro-holes were analyzed using both optical and scanning electron microscopes. In particular, it is demonstrated that the diameter size has a significant influence on the final value of the diametrical overcut while peak current and frequency parameters have a negligible effect.
Characterizing Influence Parameters in Pulsed Phase Thermography for Defect Detection in Sheet Metal Parts
Authors: Braun Q. , Hortig Dirk , Merklein Marion
Published: April 2013

Pulsed phase thermography (PPT) is a common infrared technique for quantitative nondestructive testing and evaluation (NDT&E). PPT was initially applied in the aeronautical and aerospace engineering to the detection and quantification of defects in materials with either high or low thermal conductivity, such as aluminium and composite materials. This paper presents for the first time the application of PPT-technique for defect inspection in sheet metal parts, attempting to provide a solution for an alternative quality control rather than the traditional optical survey in the press shop. The inspected defects in this paper were produced in deep drawing cups, to effectively creating various crack lengths and depths respectively in both steel and aluminium alloys. The approach of the characterizing influence parameters is primarily based on the particular parameters of the PPT-technique. These parameters were firstly classified into various categories, and a DoE model was subsequently designed to define the required experiments for a process window analysis. According to the defined process window, more accurate conclusions of defect detecting effects were achieved. Studies in the paper present the fundamental perceptions for defect inspecting in the sheet metal parts by using PPT-technique in the press shop.
Extension of the Value Stream Mapping Approach to the Comprehensive Design of a Lean Sheet Metal Manufacturing System: An Industrial Case Study
Authors: Matt Dominik T.
Published: April 2013

This paper reports the practical experiences made with extending the Value Stream Mapping (VSM) approach to the comprehensive design of a lean manufacturing system for the series production of sheet metal cable tray systems. The use of VSM for analyzing the production of repetitive units has proven to be successful in different industries. It is based on a classification of all products into product families and creates one current and future state map for each product family. This approach and the related guidelines for future state optimization are very helpful but not sufficient for a comprehensive manufacturing system (re) design, because the relation between product families value streams, the overall material flow optimization, as well as the segmentation and layout of factory remains unclear. Thus, the purpose of this paper is to develop a design procedure based on the investigation of an industrial case that allows the integrated optimization of the single value streams, their compilation in material-flow optimized production segments, and finally the (re) design of production logistics and factory layout. The findings of this research are limited due to the focused nature of a case study based research. However, the obtained results encourage assuming its transferability to similar problems.
Electric Energy Consumption Analysis of SPIF Processes
Authors: Ingarao Giuseppe , Kellens Karel , Behera Amar Kumar , Vanhove Hans , Ambrogio Giuseppina , Duflou Joost R.
Published: April 2013

Manufacturing processes, as used for discrete part manufacturing, are responsible for a substantial part of the environmental impact of products, but are still poorly documented in terms of environmental footprint. A thorough analysis on the causes affecting the environmental impact in metal forming processes, especially the innovative but very energy intensive sheet metal forming technologies required to form light-weight products, is nowadays necessary. Therefore, this paper presents an energy consumption analysis, including a power and time study, of Single Point Incremental Forming (SPIF) processes. First, the influence of the most relevant process parameters (e.g. feed rate, step down) as well as the material forming itself are analysed regarding the power demand. Moreover, a comparative study and related energy efficiency assay are carried out on two different machine tools. As the forming time proves to be the dominant factor for the total energy consumption, from environmental point of view, the overall results show many similarities with conventional machining processes. Finally, this paper reports on some potential improvement measures to reduce the SPIF energy consumption.
Effects of Draw-Bending Characteristics on Concave Wall Feature in Rectangular Deep-Drawn Parts
Authors: Phanitwong Wiriyakorn , Thipprakmas Sutasn
Published: April 2013

In recent years, the requirements on the complicated deep-drawn parts with the high dimension precision are increasingly. As the major defect, the concave wall feature which commonly encounter in the complicated deep-drawn parts of the difficult-to-deep draw material is focused. In this research, the effects of draw-bending characteristics on concave wall feature during deep-drawing process are clearly identified. The mechanism of concave wall feature related to the draw-bending characteristic was investigated and clearly identified by using the finite element method (FEM) and the experiments were also performed to validate the FEM-simulation results. On the basis of stress distribution, the effects of draw-bending characteristics on the concave wall feature could be clearly identified via the changes of stress distributions on the wall, convex feature and spring-go feature on the bottom surface, and spring-back feature on the top surface. However, comparing with U-draw bending model, the effects of draw-bending characteristics was decreased and the concave wall feature in the case of deep-drawing model was smaller than that in the case of U-draw bending model. The experiments were carried out in both cases of the deep-drawing and U-draw bending models to validate the FEM-simulation results. The FEM-simulation results showed a good agreement with the experimental results with reference to the distribution of material thickness.
Non Destructive Investigation of Defects in Composite Structures by Full-Field Measurement Methods
Authors: Péronnet Elodie , Pastor Marie Laetitia , Huillery Richard , Dalverny Olivier , Mistou Sébastien , Karama Moussa , Génot Sylvain
Published: April 2013

This paper presents different interests of non destructive full-field measurement. More precisely, it focuses on the characterization and the comparison of the X-ray tomography and two methods of infrared thermography in order to define the defect detection limits and to precise the specific application fields for each technique on multi-layered and sandwich composite structures. The obtained results are qualitatively and quantitatively analyzed.
Models of Adhesive Bonding of Hybrid Structures
Authors: Bréthous R. , Nassiet V. , Hassoune-Rhabbour B.
Published: April 2013

Adhesives are often based on polymers materials. They are good candidates in order to manufacture adhesives joint because of their thermomechanical properties and their processing which is easier than other materials. Epoxy resins are widely used as adhesives joint. We can meet them in various industrial areas like car, spatial and aerospace domains. Because of numerous combinations between epoxy and amine chemical functions, these joints may be efficient at high or at low temperature. Indeed, close to their glassy transition temperature (Tg), exists an elastic modulus / ductility couple for which, shear stress is optimum: the Optimum Stress Zone (OSZ)[ which is restricted on limited temperatures range. Our study consists in formulating an epoxy amine joint able to be efficient on an extended temperatures rangei.e.a joint able to ensure a stress continuity over a large range of temperatures, for example-50°C to 100°C. To reach this objective, we propose an evolution of the Multi Adhesive Joints (MAJ): an adhesive joint presenting a gradient of mechanical properties. To make this adhesive joint formulation possible, its necessary to control kinetics diffusion at the adhesive scale (200μm to 500μm) between the low temperature adhesive (LTA) and the high temperature adhesive (HTA). The diffusion study will be carried out by using a rheometer. For such adhesive thickness, the rheometer compliance may have an influence on the results. Therefore, this present work proposes to identify and to set up the key parameters, which allow following kinetics diffusion in a rheometer for dimensions similar to those of bonding assembly, by checking the measurements are performed in the linear viscoelastic domain. In a first part, the morphological, mechanical and thermomechanical properties of the nanostructured thermosets versus time are performed. And, the second part will deal with the optimization of the key parameters by performing dynamic shear tests versus time on HTA and LTA samples in sight of kinetics diffusion study.
Numerical Simulation of the Interaction Shock/Turbulent Boundary
Authors: Gouidmi Hamza , Benderradji Razik , Beghidja Abdelhadi
Published: April 2013

This study is fulfilled to simulate numerically the interaction phenomenon of the bidimensional compressible and supersonic flow with M=2.28 of a turbulent boundary layer with an oblique choc wave. The oblique choc wave is released and oriented by a generator of choc in an angle of θw=8° on a plate plane maintained at a constant temperature. The interaction causes the detachment of the boundary layer and make it disturbed (The case of experimental study done by J. Deleuze (1995)). The contribution on the effects of turbulence and their characteristics is represented by k-w-SST model. This model is well adapted for this type of application. This study permits to underline the coherence of our analysis with existant numerical and experimental results. This simulation is effected by means of solver which based on the spatio-temporal discretization of the complex equations of Navier-Stockes with finite volumes method. We also use the Upwind scheme of second order.
Influence of the Dimensions of the Mesh of the Fiber Grid Reinforcement of Composite Materials
Authors: Ait Tahar Kamal , Bahar R.
Published: April 2013

Currently, the composite materials make important great strides, considering their high mechanical properties. The studies relating to the conceptual, technical aspect and modeling of their mechanical behavior are more than desirable. The mechanical properties of the composite material depend on several factors as the nature of fibers, the fiber/matrix ratio, compatibility, homogeneity...
In this study, we present the results of an experimental analysis of the behavior of the composite material, under a static and a dynamic loading. The composite material is composed respectively of the glass and metal fiber reinforcement. A various dimensions of the mesh are considering. The resin used is polyester Resow 55 E. The dynamic test ( Knoop test) is carried out on various specimens made up of an polyester resin RESOW 55 E reinforced with varied powder nature. It makes it possible to measure the hardness of composite materials. The analysis of the results shows clearly that the mechanical properties are strongly influenced by the dimensions of the elementary mesh of the fiber grid reinforcement. Based on experimental results, a Weibull modulus has been established for each specimen.
Influence of the Fractal Dimension on the Mechanical Properties of Granular Materials
Authors: Melbouci Bachir , Yezli Saliha
Published: April 2013

To determine the size of a grain, we associated its form to that of a equivalent sphere. The grains size is then measured by an equivalent diameter, which is not enough to describe the behavior materials with irregular grains shape. To understand these effects, a new technique was developed by Mandelbrot (1979) which is based on the fractal geometry. To clarify this notion, the grains shape is characterized using the fractal dimension (Df), which is a number measuring the degree of irregularity or the fragmentation of a grain. Mechanical tests were performed. The fractal dimension was calculated for different grains constituting the samples before and after each test while studying its evolution after crushing. The results confirm that the fractal dimension affects the measurement of mechanical properties of the granular materials.
Till geochemical signatures of the Halfmile Lake Zn-Pb-Cu volcanogenic massive sulphide deposit, Bathurst Mining Camp, New Brunswick
Authors: Budulan G , McClenaghan M B , Parkhill M
A , Layton-Matthews D , Pyne M
Published: April 2013

The Halfmile Lake study was conducted as part of the Geological Survey of Canada's Targeted Geoscience Initiative (TGI-3) Program under the Deep Search Project to document the geochemical and indicator mineral signatures of the till around the Halfmile Lake
Zn-Pb-Cu volcanogenic massive sulphide (VMS) deposit in northcentral New Brunswick. Bedrock and till samples were collected in 2007 and 2008 at varying distances up- and down-ice of the deposit. Sampling was focused on the South Upper AB zone because it is the surface expression of the deposit and
is capped by a preglacial gossan. Mineralization consists of a Curich stringer zone stratigraphically overlain (structurally underlain) by a Pb-Zn massive sulphide zone. A metal-rich gossan composed of secondary minerals is found at surface. Till in the Halfmile Lake deposit study area is thin
(<2 m), light olive brown to dark brown in colour, and silty sand to sandy silt in texture. Ice flow across the deposit area was towards the east-northeast. The pathfinder elements in the <0.063 mm fraction of till that define the signature of the deposit include Cu, Pb, Zn,
Ag, As, Au, Bi, Hg, Sb, Se, and Sn. Elevated concentrations of these elements in till down-ice are consistent with the ore mineralogy of the Halfmile Lake deposit and demonstrate that till geochemistry is a useful tool for detecting VMS mineralization in the glaciated terrain of the Bathurst Mining
Camp.
In situ emergence timing of large and small crabgrass in residential turfgrass of southern Ontario
Authors: Turner Fawn A. , Van Acker Rene C.
Published: April 2013

Turner, F. A. and Van Acker, R. C. 2013. In situ emergence timing of large and small crabgrass in residential turfgrass of southern Ontario. Can. J. Plant Sci. 93: 503–509. Large, Digitaria sanguinalis (L.) Scop., and small, Digitaria ischaemum (Schreb.) ex Muhl., crabgrass are problem weeds in turfgrass. Due to an increasing number of cosmetic pesticide bans in Canada there is a need to better understand the biology and ecology of crabgrass in order to develop and hone management approaches. The assessment of crabgrass recruitment timing is particularly relevant to its management, including the timing of alternative herbicide applications. This study focused on determining the emergence timing of established populations of large and small crabgrass in typical residential turfgrass stands in southern Ontario. Small crabgrass emerged earlier than large crabgrass at 346 and 515 growing degree days (GDD), respectively. In typical southern Ontario lawns both small and large crabgrass emerge after cool-season turfgrass has established and emergence continues late into the summer. For example, even within the last 2 wk of July we observed over 700 seedlings m–2 of large crabgrass emerging in some observation plots. This study also confirmed that small crabgrass emerges earlier than large crabgrass. There was a greater difference in emergence timing between species rather than among sites, suggesting that it is important to differentiate between species when timing management approaches. The late and prolonged emergence of crabgrass makes residential lawns that are not well maintained susceptible to infestation for a long portion of the growing season. This study also demonstrated that cumulative GDD may be a reliable measure for tracking crabgrass emergence suggesting, that it could be used as a tool for management, including the application of alternative herbicides. This study reinforces the importance of maintaining healthy and dense turf stands throughout the season as a deterrent to crabgrass infestations.
Remarks on the Lefschetz standard conjecture and hyperkähler varieties
Authors: Charles François
Published: April 2013

We study the Lefschetz standard conjecture on a smooth complex projective variety

X

. In degree

2

, we reduce it to a local statement concerning local deformations of vector bundles on

X

. When

X

is hyperkähler, we show that the existence of nontrivial deformations of stable hyperholomorphic bundles implies the Lefschetz standard conjecture in codimension

2

.
Medical Student Appraisal
Authors: Markman T.M. , Sampognaro P.J. , Mitchell S.L. , Weeks S.R. , Khalifian S. , Dattilo J.R.
Published: April 2013

Background: Medical students are often afforded the privilege of counselling patients. In the past resources were limited to pen and paper or anatomic models. The evolution of mobile applications allows for limitless access to resources that facilitate bedside patient education.

Objectives: To evaluate the utility of six applications in patient education and promote awareness of implementing mobile resources in clinical care.

Methods: Six medical students rotating on various clerkships evaluated a total of six mobile applications. Strengths, limitations, and suggested uses in clinical care were identified. Applications included MeditoonsTM, VisiblePatientTM, DrawMDTM, CardioTeachTM, Visual AnatomyTM, and 360° Patient Education SuiteTM. Data was generated from narrative responses supplied by each student during their evaluation period.

Results: Bedside teaching was enhanced by professional illustrations and animations depicting anatomy and pathophysiology. Impromptu teaching was facilitated, as resources were conveniently available on a student’s smartphone or tablet. The ability to annotate and modify images and subsequently email to patients was an extraordinary improvement in provider-patient communication. Universal limitations included small smartphone screens and the novelty of new technology.

Discussion: Mobile applications have the potential to greatly enhance patient education and simultaneously build rapport. Endless opportunities exist for their integration in clinical practice, particularly for new diagnoses, consent for procedures, and at time of discharge. Providers should be encouraged to try new applications and utilize them with patients.

Citation: Markman TM, Sampognaro PJ, Mitchell SL, Weeks SR, Khalifian S, Dattilo JR. Medical student appraisal: Applications for bedside patient education. Appl Clin Inf 2013; 4: 201–211

http://dx.doi.org/10.4338/ACI-2013-01-R-0007
Stratospheric loss and atmospheric lifetimes of CFC-11 and CFC-12 derived from satellite observations
Authors: Minschwaner K. , Hoffmann L. , Brown A. , Riese M. , Müller R. , Bernath P. F.
Published: April 2013

Abstract. The lifetimes of CFC-11 and CFC-12 have been evaluated using global observations of their stratospheric distributions from satellite-based instruments over the time period from 1992 to 2010. The chlorofluorocarbon (CFC) datasets are from the Cryogen Limb Array Etalon Spectrometer (CLAES), the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA-1 and CRISTA-2), the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), and the Atmospheric Chemistry Experiment (ACE). Stratospheric loss rates were calculated using an ultraviolet radiative transfer code with updated cross section and solar irradiance data. Mean steady-state lifetimes based on these observations are 44.7 (36–58) yr for CFC-11 and 106.6 (90–130) yr for CFC-12, which are in good agreement with the most recent WMO ozone assessment. There are two major sources of error in calculating lifetimes using this method. The first important error arises from uncertainties in tropical stratospheric observations, particularly for CFC-11. Another large contribution to the error is due to uncertainties in the penetration of solar ultraviolet radiation at wavelengths between 185 and 220 nm, primarily in the tropical stratosphere between 20 and 35 km altitude.
Exploring the nature of air quality over southwestern Ontario: main findings from the border air quality and meteorology study
Authors: Brook J. R. , Makar P. A. , Sills D. M. L. , Hayden K. L. , McLaren R.
Published: April 2013

Abstract. This paper serves as an overview and discusses the main findings from the Border Air Quality and Meteorology Study (BAQS-Met) in southwestern Ontario in 2007. This region is dominated by the Great Lakes, shares borders with the United States and consistently experiences the highest ozone (O3) and fine particulate matter in Canada. The purpose of BAQS-Met was to improve our understanding of how lake-driven meteorology impacts air quality in the region, and to improve models used for forecasting and policy scenarios. Results show that lake breeze occurrence frequencies and inland penetration distances were significantly greater than realized in the past. Due to their effect on local meteorology, the lakes were found to enhance secondary O3 and aerosol formation such that local anthropogenic emissions have their impact closer to the populated source areas than would otherwise occur in the absence of the lakes. Substantial spatial heterogeneity in O3 was observed with local peaks typically 30 ppb above the regional values. Sulphate and secondary organic aerosol (SOA) enhancements were also linked to local emissions being transported in the lake breeze circulations. This study included the first detailed evaluation of regional applications of a high resolution (2.5 km grid) air quality model in the Great Lakes region. The model showed that maxima in secondary pollutants occur in areas of convergence, in localized updrafts and in distinct pockets over the lake surfaces. These effects are caused by lake circulations interacting with the synoptic flow, with each other or with circulations induced by urban heat islands. Biogenic and anthropogenic emissions were both shown to play a role in the formation of SOA in the region. Detailed particle measurements and multivariate receptor models reveal that while individual particles are internally mixed, they often exist within more complex external mixtures. This makes it difficult to predict aerosol optical properties and further highlights the challenges facing aerosol modelling. The BAQS-Met study has led to a better understanding of the value of high resolution (2.5 km) modeling for air quality and meteorological predictions and has led to several model improvements.
Effects of anomalous high temperatures on carbon dioxide, methane, dissolved organic carbon and trace element concentrations in thaw lakes in Western Siberia in 2012
Authors: Pokrovsky O. S. , Shirokova L. S. , Kirpotin S. N. , Kulizhsky S. P. , Vorobiev S. N.
Published: April 2013

Abstract. During the anomalous hot summer in 2012, surface air temperatures in Western Siberia were 5 to 10 °C higher than those observed during the previous period of > 30 yr. This unusual climate phenomenon provided an opportunity to examine the effects of short-term natural heating of water in thermokarst ponds and lakes in discontinuous permafrost zones and compare these observations to previous field results obtained when the temperature was normal during the summer of 2010 in the same region. Thermokarst bodies of water shrank significantly, water levels dropped approximately 50 cm in large lakes and small (< 10–100 m2) ponds, and shallow soil depressions disappeared. Based on samples from ~ 40 bodies of water collected previously and in 2012, first-order features of changes in chemical composition in response to increased water temperatures (from 14.1 ± 2.2 to 23.8 ± 2.3 °C in 2010 and 2012, respectively) were established. In these thermokarst bodies of water that covered a full range of surface areas, the average conductivity and pH were almost unchanged, whereas dissolved organic carbon (DOC), Cl− and SO42− concentrations were higher by a factor of ~ 2 during summer 2012 compared to periods with normal temperatures. Similarly, most divalent metals and insoluble trivalent and tetravalent elements were more concentrated by a factor of 1.7–2.4 in the summer of 2012 than normal periods. The average concentrations of dissolved CO2 and CH4 during the hot summer of 2012 increased by factors of 1.4 and 4.9, respectively. For most of the trace elements bound to colloids, the degree of colloidal binding decreased by a factor of 1.44 ± 0.33 (for an average of 40 elements) during the hot summer of 2012 compared to normal periods. Increases in CO2 and CH4 concentrations with the decreasing size of the body of water were well-pronounced during the hot summer of 2012. The concentrations of CO2 and CH4 significantly increased by factors of 5 and 150, respectively, in small (≤ 102 m2) compared to large (≥ 104 m2) thermokarst (thaw) lakes. Taken together, these trends suggest that, for a conservative scenario of lake size distribution, lake water warming at high latitudes will produce (1) a significant increase in methane emission capacity from thaw lake surfaces; (2) decrease of molecular sizes of TE complexes and increase of potential bioavailability of metal micronutrients in water columns; and (3) relatively conservative responses by CO2, DOC and trace element concentrations.
Simulating boreal forest carbon dynamics after stand-replacing fire disturbance: insights from a global process-based vegetation model
Authors: Yue C. , Ciais P. , Luyssaert S. , Cadule P. , Harden J. , Randerson J. , Bellassen V. , Wang T. , Piao S. L. , Poulter B. , Viovy N.
Published: April 2013

Abstract. Stand-replacing fires are the dominant fire type in North American boreal forest and leave a historical legacy of a mosaic landscape of different aged forest cohorts. To accurately quantify the role of fire in historical and current regional forest carbon balance using models, one needs to explicitly simulate the new forest cohort that is established after fire. The present study adapted the global process-based vegetation model ORCHIDEE to simulate boreal forest fire CO2 emissions and follow-up recovery after a stand-replacing fire, with representation of postfire new cohort establishment, forest stand structure and the following self-thinning process. Simulation results are evaluated against three clusters of postfire forest chronosequence observations in Canada and Alaska. Evaluation variables for simulated postfire carbon dynamics include: fire carbon emissions, CO2 fluxes (gross primary production, total ecosystem respiration and net ecosystem exchange), leaf area index (LAI), and biometric measurements (aboveground biomass carbon, forest floor carbon, woody debris carbon, stand individual density, stand basal area, and mean diameter at breast height). The model simulation results, when forced by local climate and the atmospheric CO2 history on each chronosequence site, generally match the observed CO2 fluxes and carbon stock data well, with model-measurement mean square root of deviation comparable with measurement accuracy (for CO2 flux ~100 g C m−2 yr−1, for biomass carbon ~1000 g C m−2 and for soil carbon ~2000 g C m−2). We find that current postfire forest carbon sink on evaluation sites observed by chronosequence methods is mainly driven by historical atmospheric CO2 increase when forests recover from fire disturbance. Historical climate generally exerts a negative effect, probably due to increasing water stress caused by significant temperature increase without sufficient increase in precipitation. Our simulation results demonstrate that a global vegetation model such as ORCHIDEE is able to capture the essential ecosystem processes in fire-disturbed boreal forests and produces satisfactory results in terms of both carbon fluxes and carbon stocks evolution after fire, making it suitable for regional simulations in boreal regions where fire regimes play a key role on ecosystem carbon balance.
Simulations of the mid-Pliocene Warm Period using two versions of the NASA/GISS ModelE2-R Coupled Model
Authors: Chandler M. A. , Sohl L. E. , Jonas J. A. , Dowsett H. J. , Kelley M.
Published: April 2013

Abstract. The mid-Pliocene Warm Period (mPWP) bears many similarities to aspects of future global warming as projected by the Intergovernmental Panel on Climate Change (IPCC, 2007). Both marine and terrestrial data point to high-latitude temperature amplification, including large decreases in sea ice and land ice, as well as expansion of warmer climate biomes into higher latitudes. Here we present our most recent simulations of the mid-Pliocene climate using the CMIP5 version of the NASA/GISS Earth System Model (ModelE2-R). We describe the substantial impact associated with a recent correction made in the implementation of the Gent-McWilliams ocean mixing scheme (GM), which has a large effect on the simulation of ocean surface temperatures, particularly in the North Atlantic Ocean. The effect of this correction on the Pliocene climate results would not have been easily determined from examining its impact on the preindustrial runs alone, a useful demonstration of how the consequences of code improvements as seen in modern climate control runs do not necessarily portend the impacts in extreme climates. Both the GM-corrected and GM-uncorrected simulations were contributed to the Pliocene Model Intercomparison Project (PlioMIP) Experiment 2. Many findings presented here corroborate results from other PlioMIP multi-model ensemble papers, but we also emphasise features in the ModelE2-R simulations that are unlike the ensemble means. The corrected version yields results that more closely resemble the ocean core data as well as the PRISM3D reconstructions of the mid-Pliocene, especially the dramatic warming in the North Atlantic and Greenland-Iceland-Norwegian Sea, which in the new simulation appears to be far more realistic than previously found with older versions of the GISS model. Our belief is that continued development of key physical routines in the atmospheric model, along with higher resolution and recent corrections to mixing parameterisations in the ocean model, have led to an Earth System Model that will produce more accurate projections of future climate.
The environmental impact of the Puyehue-Cordon Caulle 2011 volcanic eruption on Buenos Aires
Authors: Raga G. B. , Baumgardner D. , Ulke A. G. , Torres Brizuela M. , Kucienska B.
Published: April 2013

Abstract. On 4 June 2011, the volcanic complex Puyehue-Cordon Caulle located in the Chilean Andes erupted, producing a plume of gases and particles that eventually circled the Southern Hemisphere, disrupting air travel and depositing ash in large quantities. On eight occasions, the plume passed over the city of Buenos Aires, Argentina, leading local authorities to close the two international airports. The eruption occurred during an on-going field campaign when measurements of the properties of atmospheric aerosol particles were being made in Buenos Aires as part of a year-long study of the physical and optical properties of aerosol at one site in the city. The suite of instruments deployed in Buenos Aires were not tailored to measurements of volcanic ash, but were designed to characterize urban conditions. Nevertheless, these measurements were analyzed for periods when vertical profiles of aerosol backscatter, made with a ceilometer, clearly showed the presence of the volcano plume over the research site and resulted in airport closure. Aerosol optical thickness derived from AERONET, MODIS and a ceilometer at our research site, all show enhanced values clearly indicating that the three platforms identified the volcanic plume simultaneously. However, a quantitative comparison of the different estimates proves difficult, suggesting large spatial and temporal variability of the plume. Our results indicate that the number concentration of condensation nuclei (CN), the mass concentration of particle-bound polycyclic aromatic hydrocarbons (PPAH) and the light absorption coefficient exceeded the average background values by more than one standard deviation during the events of volcanic plume. The anomalous concentrations of CN suggest new particle formation, presumably from the conversion of SO2, while the anomalous concentrations of PPAH may come from the uptake of PAHs on the plume particles or from chemical reactions on the surface of plume particles. The anomalous absorption coefficients indicate that plume particles may contain certain compounds that can absorb radiation at 550 nm. Another possible explanation consistent with the observations is the scavenging of black carbon from urban sources as the plume descends through the boundary layer to the surface. In addition, the volcanic plume influenced the local meteorology resulting in a decrease of the temperature when compared to the average temperature during days with no plume present.
ANÁLISE DAS PROPRIEDADES FÍSICAS E MECÂNICAS DO CONCRETO PRODUZIDO COM RESÍDUO SÓLIDO DE CERÂMICA VERMELHA
Authors: Fabian S. Campos Cassio , Bozette Mazini Giovane , A. da Silva Neto Guilherme
Published: April 2013

The construction industry accounts for the largest share of consumption of natural resources among all other areas, about 50%. Consequently is also the largest generator of waste. One of these tailings is red ceramic, which due to its fragility break easily generate large amount of debris. This project aimed to examine the possibility of reuse of waste as aggregate for concrete comparing their physical and mechanical properties, with conventional concrete. We compared the behaviors of different traits in concrete with a gradual replacement of 20% of natural coarse aggregate by recycled aggregate red ceramic to achieve 100% recycled aggregate, evaluating possible changes in density, absorption and voids, as well as the mechanical compression. The reference concrete results presented in the order of 25 MPa at 28 days of age, since the concrete produced with recycled aggregates showed lower results of the compressive strength of up to30%. The other indices also suffered physical changes as the slump that had values 4 times higher, the level of absorption and voids which increased 2-3 three times in concrete with recycled aggregate. This happens due to the difference between the densities of crushed stone and ceramics. Although the ceramic adversely affect the mechanical properties, this difference becomes lighter concrete, or decreases its specific weight, which may be favorable in some situations.
Best Practices Guide Valve Selection for Pressure Zone Management
Authors: Clarke Brad
Published: April 2013

Consider these guidelines when choosing valves to optimize pressure zone functionality and performance.
Increase Utility Revenue without Increasing Rates
Authors: Morgan Willie J.
Published: April 2013

In rough economic times, utilities must search for ways to lower costs and increase revenue. Accurate metering and billing can be powerful ways to boost a company's bottom line.
A review of the genus Stenochlaena (Blechnaceae, subfamily Stenochlaenoideae)
Authors: Chambers T. Carrick
Published: April 2013

Stenochlaena is a small but widespread genus confined to the tropics and subtropics of the Old World. A key to the species, updated descriptions, distribution-maps, and detailed drawings are provided. Also included is a key to assist in separating several genera that are most often confused with Stenochlaena. There is morphological evidence suggesting that hybrids may exist between several species in Malesia.Although primarily a rainforest genus, the distribution patterns of the various species of Stenochlaena appear closely related to ecological requirements; the hemiepiphytic members of the genus are most frequently present along forest margins in relatively high light conditions with access to a moist soil or an aquatic environment but not necessarily to perpetually humid atmospheric conditions.