The University of Newcastle, Australia

Conference Program

Plenary Speakers

Emeritus Professor George Klinzing - University of Pittsburgh, USA

Emeritus Professor George Klinzing has been researching and teaching in pneumatic conveying for over 50 years producing articles on various topics in solids handling.  He has interacted worldwide with industrial and academic leaders in the field and directed 30 Ph.D. dissertations and over 50 M.S. theses.  He has written two books in gas solid transport one being in its third edition.  His students have gone on to be leaders in academia, industry and government. He currently holds the position of Emeritus Professor of Chemical Engineering at the University of Pittsburgh.

George Klinzing

Plenary Presentation: Pneumatic Conveying Troubleshooting: AI Approaches

Professor Andre Katterfeld - Otto-von-Guericke-University Magdeburg, Germany

Prof. Dr.-Ing. André Katterfeld holds the chair of Material Handling Systems at the Institute of Logistics and Material Handling Systems of the Otto-von-Guericke-University Magdeburg, Germany. As a mechanical engineer, he received a PhD on the analysis of tube chain conveyors in 2005. Prof. Katterfeld is an internationally known expert in the field of material handling with expertise in the mechanical transportation of bulk materials. He has a strong reputation in academic and industrial application of the Discrete Element Method (DEM) in the field of material handling. This work includes the characterisation, calibration and validation of real bulk material behaviour for numerical modelling. Prof. Katterfeld has a long-standing collaboration with the University of Newcastle as a Conjoint Associate Professor since 2012.

Andre Katterfeld

Plenary Presentation: A Standard Calibration Approach for DEM Parameters of Cohesionless Bulk Materials

Dr Robin Steven - Continental's North American Conveyor Belt Group CBG

Dr Robin Steven graduated in 1974 with a PhD in Mechanical Engineering from the Queens University of Belfast, N. Ireland. He has worked at the Goodyear Tire and Rubber Company Technical Center in Craigavon, N. Ireland for 9 years designing and developing new products and manufacturing techniques for wire braid hoses, specialty hoses, and power transmission belts for automotive applications. He worked in Goodyear S. Africa Development group for 3 years working on conveyor belt design and production, setting up cut edge v-belt production, and the installation and commissioning of a new solid woven PVC belt manufacturing operation. He also worked in Goodyear, São Paulo, Brazil plant for 5 years as head of a technical support group (GITC) for all Goodyear S. American plants producing hose, v-belts and conveyor belts. He worked in Goodyear Tire & Rubber Co., then Veyance Technologies Inc., now Continental’s  Marysville conveyor belt plant in Ohio, USA for 28 years working in the Development group as team leader of the steel cord and pipe conveyor belt team. His current position is Continental’s North American Conveyor Belt Group (CBG) Chief Global Engineer for Steel Cord Conveyor Belts.

Robin Steven

Plenary Presentation: OLC/LRR/High Strength Steel Cord Belts

Dr. Fabiano Ximenes - NSW Department of Primary Industries

Dr Fabiano Ximenes has a Masters (ANU) and PhD (UNE) in wood science. He has worked for the NSW government since 2000 on a number of forestry projects, with a strong focus on characterization of biomass. Recent projects include leading the NSW component of the Australian Biomass for Bioenergy Assessment, the North Coast Residues Project and the Biomass for Bioenergy Project under the NSW Climate Change Fund. Fabiano's current position is a Senior Research Scientist - Forest Science - NSW Department of Primary Industries Forestry.

Fabiano Ximenes

Plenary Presentation: Opportunities and challenges for increased use of biomass in New South Wales

Accepted Abstracts

Disclaimer: please note that abstract acceptance does not imply paper acceptance neither does it ensure the papers will be in the final program.

General Topics on Materials Handling

Bulk Solids Handling-A Chemical Engineer’s Perspective - Grant Wellwood, Jenike & Johanson, Australia

Prediction and Measurement of High Pressure Flow - Edward P Alexander, Peter W Wypych, Peter C Arnold, University of Wollongong, Australia

A Review of the Wall Yield Locus in the Context of Wet and Sticky Ores - Terrance J Frangakis, John Sheer, University of the Witwatersrand, South Africa

A Revised Yielding Theory of Bulk Materials Incorporating Adhesion - Michael Carr, Alan Roberts, Craig Wheeler, The University of Newcastle, Australia

A Light Transmission Method to Measure the Size Distribution and Concentration of Pulverized Coal - Shouxuan Qin, Xiaoshu Cai, University of Shanghai for Science & Technology, China

Effects of Segregation on Granulated NPK Process Sieving – A Case Study - Felipe Mendes Cardoso Carvalho, Castech, Brazil

A Dynamic Model for Materials Storage to Model Size Segregation - Ziming Ye, Mohsen Yahyaei, Marko Hilden, Malcolm Powell, The University of Queensland, Australia

Moving and Mixing Materials with a Mechanical Intestine - Gerald K. Olson, Clive E. Davies, Luke Fullard, Rose Y.G.Davies, Gourab Sen Gupta, Massey University, New Zealand

Some Observations from Mixing Granular Binary Mixtures in a Short Length Rotating Drum - David B Hastie, University of Wollongong, Australia

Optimization of Sampling Practices at Córrego do Sítio Metallurgical Plant - Marcus F. Magalhães, Ana Carolina Chieregati, Vinícius M. de Assis, Anglogold Ashanti, Brazil, University of São Paulo, Brazil

Life Cycle Costing: A Bridge Reclaimer Case Study - Eric Lau, South32, Australia

Research and Development of Powder Filling Techniques for Handling Hazardous Materials Prior to Hot Isostatic Pressing - Simon Chung, Sam Moricca, David Hastie, Andrew Grima and Peter Wypych, Gravitas Technologies, Australia, University of Wollongong, Australia

In Extremis: Bulk Solid Flow under Elevated and Cryogenic Temperatures - Denis Schütz, Timothy Aschl, Anton Paar, Austria

Solid State Material Driven Turbine - Michael Prenner, University of Leoben, Austria

Energy Absorption in Erosion and Fragmentation - Avi Uzi and Avi Levy , Ben-Gurion University of the Negev, Israel

Investigation of Impingement Angle Influence on Impact Wear of Different Metal Liners by Employing a Novel Impact Wear Tester - Caroline Gomes de Oliveira, Jayne O'Shea, Jie Guo, Anna Giacomini, Kenneth Williams, The University of Newcastle, Australia

Design of Optimized Convex Pattern Surface for Wear Tests in a Test Rig - Yunpeng Yan, Wouter Vreeburg, Craig Wheeler, Dingena Schott, Delft University of Technology, The Netherlands, The University of Newcastle, Australia

Abrasive Wear Behavior of Commercial Wear Steel Plates used in Chutes for Iron Ore Applications - Jimmy Penagos, Eleir Bortoleto, Gustavo Tressia, Amilton Sinatora, Vale, Brazil

Belt Conveying

Keynote Paper TBA presented by Professor Alexander Harrison

Reducing Belt Conveyor Transfer Impact Energy using a Dynamic Idler  - Cameron Portelli , Kinder Australia

Autonomous Weigh Roller Unit - Paul Chase, Leonard Ian Burrel, Vladimir Sin, Craig Wheeler, Paul Munzenberger, Control Systems Technology, Australia, The University of Newcastle, Australia, Aspec Engineering, Australia

Performance-based Design: Case Study of Conveyor Belt Idlers - Tiago Cousseau, Philip v. Pritzelwitz, Felipe R. da Fonseca, Federal University of Technology of Parana, Curitiba, Brazil, Vale S.A., Brazil

Technical and Economic Considerations for the Selection of Drive Technology for High Powered Belt Conveyors - Thomas J Hicks, Bechtel Australia

Drive Rollers to Increase the Capacity of Belt Conveyors - Daniel Hötte, Lars Bindszus, Ludger Overmeyer, Institute of Transport and Automation Technology, Leibniz Universität Hannover, Germany

Energy Savings for Belt Conveying Systems by Preview Control - Dingena Schott, Yusong Pang,Tiezhu Qiao, Gaowei Ya, 1Delft University of Technology, The Netherlands, Taiyuan University of Technology, Tianyuan, China

Evaluation of Test Methods for the Determination of Belt Cover Wear Resistance - Shaun C Reid, Brendan Beh, Craig A Wheeler, TUNRA Bulk Solids, Australia, The University of Newcastle, Australia

Automatable Splicing Method for Steel Cord Conveyor Belts using High-Pressure Water Jetting - Patrick Rieme, Markus Mlinaric, Thomas Hassel, Ludger Overmeyer, Institute of Transport and Automation Technology, Leibniz Universität Hannover, Institute of Materials Science, Leibniz Universität Hannover, Germany

How to Estimate the Life of a Conveyor Belt by Linear Regression and Determine its Reliability and Risk Curve - Willian de Castro Toledo, Mineração Rio do Norte, Brazil

Intelligent Maintenance of Belt Conveyors using Machine Learning - Xiangwei Liu, Deli Pei, Gabriel Lodewijks, Zhangyan Zhao, Wuhan University of Technology, Wuhan, China, Beijing, China, The University of New South Wales, Australia

Dynamic Conveyor Belt Simulation using the Discrete Element Method - Eric Fimbinger, University of Leoben, Austria

Belt Mistracking-Simulation and Measurements of Belt Sideways Dymanics - Hendrik Otto, Andre Katterfeld, University of Magdeburg, Germany

Remote NDT Measurement for the Effective Maintenance of Steel Cord Belts" by K. Lee's, Data Analyst, Conveyor Technologies Pty Ltd and CbmI Pty Ltd,  Australia

Pipe Belts – Advantages, Challenges and Applications - Stephan Hötte, Belt Conveyor Group, Continental, Division ContiTech, Australia

Research on Contact Relationship between Conveyor Belt and Ilders of Pipe Belt Conveyor  - Xinrong Gong, Weigang Song, Bo Wang, Zigong Conveying Machine Co. LTD, China, Northeastern University, Shenyang, China

Case Study of Pellet Pipe Conveyor Belt (ST1800) Frequent Failure - Kaushal Kumar Singh, Tata Steel, India

The Way to Reduce to Selecting Breaking Strength for Conveyor Belt: From Maximum Tension to Maximum Stress - Weigang Son,Yong Gao, Bo Wang, M engjie Zhao, Northeastern University, Shenyang, China, Northern Heavy Industries Co, LTD, Shenyang, China

Development of a Novel Clamping System Arrangement and Method for Measuring the Tension in a Conveyor Belt - Graham Holford, Jason Willis, Dusan Ilic, Craig Wheeler, TSGlobal, Australia, Centre for Bulk Solids and Particulate Technologies, University of Newcastle, Australia

3iS - Intelligent IoT Idler Stations for the Identification of Damaged Idler Bearings - Andre Katterfeld, Christian Richter, Karl Fessel, Rolf Schwandtke, Yevgeniy Chumachenko, University of Magdeburg, Germany, Artur Kipper, Germany

Steep Incline and Vertical Conveyors – Advantages, Challenges and Applications, Dipl.-Ing. Zoltán Tarpay, Conveyor Belt Group, Continental, Division ContiTech, Germany

A Dynamic Analysis of the Rail Conveyor System - Aleef Rahman, Peter Robinson, Michael J Carr and Craig A Wheeler, The University of Newcastle, Australia.

Storage & Handling

Upgrading the Matraville Gypsum Handling and Storage System - Alfons Montebello, Roger A Hayim, Brad A Allsopp, Knauf Plasterboard, Australia, WSP Australia

Transfer Chute Evaluation with Coupled DEM-CFD Analysis for Application in Dust Control - Leonardo Quintão Santos, Arcelor Mittal, Brazil

Design Modification of Pellet Plant Dryer Feed Chute - Saprativ Basu, Samik Nag, Arijit Chakrabarty, Sandip Kumar Chakraborty, Abhinav Kumar, Kishore Behera, Indrajit Paul, Tatal Steel Ltd, India

Design of a Granular Materials Transfer System: A combined Analytical and Computational mechanics approach - Gonzalo Emanuel Echaniz, Nicolas Aldrete, Alejandro Benites, Federico Larco, Ternium Argentinar, Argentina, NOITEC S.A., Argentina

Influence of Bulk Solids Settlement on the Initial Gate Loads in Storage Bins - Alan Roberts, Jiahe Shen, Bin Chen, Brendan Beh and Timothy Donohue, TUNRA Bulk Solids, Australia, The University of Newcastle, Australia

Some Theoretical Consideration of Stress States at the Hopper Feeder Interface - Jie Guo, Alan W Roberts, Mark G Jones, The University of Newcastle, Australia

Instability Analysis of Vertical Stiffeners of Cylindrical Steel Silos Made of Corrugated Sheets - Ana Carolina Albernaz Rodrigues, Carlito Calil Jr, 1University of  São Paulo, Brazil

Measurement of Fill Volume of a Storage Vessel by Optical Means - Mohamed Barzegar, Gabe P. Redding, Clive E Davies, Luke Fullard, Miles C Graffon, Massey University, New Zealand, Biological Systems Modelling, New Zealand

A Stochastic Framework for Predicting Transfer Chute Blockages Based on Materials Properties  - Priscilla G Freire, Kenneth C Williams, Jayne O'Shea, The University of Newcastle, Australia

Innovative Design, Safety and Performance Enhancements of Air Cannons - Mick Hutton,  James Stievenard, ESS Engineering

Pneumatic & Hydraulic Conveying

Keynote Paper: The Role of Ar Number in Particle-Fluid Flows - Haim Kalman, Ben-Gurion University of the Negev, Israel

Calibration of Coupled CFD DEM Using a Bench Scale Pseudo 2D Single Spout Fluidised Bed Apparatus - Aleksej Lavrinec, Ognjen Orozovic, Jason Willis, Kenneth C Williams, Mark G Jones, The University of Newcastle, Australia

Assessment on Mode Transition in Fluidized Dense Phase Pneumatic Conveying based on Wavelet Energy Distribution - Yassin Alkassar, Vijay K Agarwal, R. K. Pandy, Niranjana Behera, Mark G Jones, IIT, India, VIT University, India, The University of Newcastle, Australia

Rheological study of copper, nickel, magnetite concentrates and gold ore - Thomas F Bunn, Wei Chen , TUNRA Bulk Solids, Australia, Bradken, Australia

Pneumatic Conveying Troubleshooting - AI Approaches - George Klinzing, University of Pittsburgh, USA

Investigation of Wood Pellet breakage during pneumatic conveying processes  - Julian Jägers, Siegmar Wirtz, Viktor Scherer, Ruhr-University Bochum, Germany

Development of an optimised gas cyclone for an industrial fluid bed furnace system - Therese Amili, Chandana Ratnayake, Finn Stalesen, Glencore Nikkelverk AS, Norway, SINTEF Tel-Tek SINTEF Industry, Norway, University of South-Eastern Norway, Norway

Velocities and Pressures Related to Single Plug Flow in Horizontal Pipe - Anubhav Rawat, Haim Kalman, Ben-Gurion University of the Negev, Israel

The Pressure Relationships of the Particle Exchanges in Horizontal Slug Flow Pneumatic Conveying - Ognjen Orozovic, Aleksej Lavrinec, Kenneth C Williams, Mark G Jones, George Klinzing, W. Clarke, The University of Newcastle, Australia, University of Pittsburgh, USA

Bends Pressure Drop in Horizontal and Vertical Dilute Phase Pneumatic Conveying Systems - Naveen M. Tripathi, Dimitri Portniakov, Avi Levy, Haim Kalman, Ben-Gurion University of the Negev, Israel

Issues with Dry Fly Ash Conveying in a Thermal Power Plant  (ash evacuation and transportation system - challenges and their addressal) - Vijay. K. Agarwal, I. K. Rajdeva and Ujjwal Chowdhury, Indian Institute of Technology Delhi (India), Ex-NTPC (India) , NTPC (India)

Biomass, Dust & Environment

Keynote Paper: Dust Explosion Venting in Silos - Alvaro Ramirez-Gomes, University Madrid, Spain

Overview of Forest Biomass Harvesting Studies in Australia - Mohammad R Ghaffariyan, University of Sunshine Coast, Australia

Influence of Chemical Composition, Pre-treatment and Genetic Variance of Eucalyptus Biomass on Sugar Accessibility and Metabolite Composition - Jorge Lepikson-Neto, Bianca Cruzio, Mariana Rebouças, Marcelo M. Carazolle, Carolina Andrade, Gonçalo G.A.G. Pereira, SENAI Institute for Biomass Innovation, Brazil, LGE State University of Campinas, Brazil

The Effect of Biomass Pellet Length on the Breakage Behaviour: Comparison Between Torrefied and Non-Torrefied Biomass Pellets - Hamid Gilvari, Wiebren de Jong, Dingena L. Schott, Delft University of Technology, The Netherlands

A General Discrete Element Contact Model for Biomass Material - Dean Ellis, Wei Chen, Dusan Ilic, Kenneth Williams, The University of Newcastle, Australia

Developing Research on Water and Chemicals for Management of Bulk Product Dust Emissions during Storage, Handling and Transportation - John Planner, Introspec Consulting

Dust Suppression Efficiency of Spraying Systems – A Review - Rongfu Liao, Peter Wypych, Renhu Pan, David B Hastie, Jon Roberts, University of Wollongong, Australia, Fujian Longking Co Ltd, China

Prediction of Dust Emissions – An Experimental-Numerical Approach - Nadja Schwindt, Daniel Schulz, Harald Kruggel-Emden, Eberhard Schmidt, University of Wuppertal, Germany, Technical University Berlin, Germany

The Effects of Reverse Jet Pulse Over-Pressurisation on Dust Filter Performance - Richard J Farnish, Hafid Beladi, Stefan Zigan, University of Greenwich, UK

The Effects of Varied Temperature when Conducting AS4156.6 Dustiness Testing - Ian Frew, David B Hastie, John Webb, Renhu Pan, University of Wollongong, Australia, Fujian Longking Co Ltd, China

Revised Coal Dustiness Test Method AS4156.6 - Part 2: Preparation - Dusan Ilic, Alekesj Lavrinec, Kenneth Williams, The University of Newcastle, Australia

Investigation into Effects of Cyclic Particle Loading onto a Filter Media - Richard J Farnish, Hafid Beladi, Stefan Zigan, University of Greenwich, UK

Challenges and Solutions of Dust Suppression During Bulk Materials Unloading into intake Hoppers - Olha Lyeskakova, Mideco, Australia

Simulation & Modelling

Insights into Granular Mechanics Through Neutron Scattering - Christopher M Wensrich, Jubert Pineda, Vladimir Luzin, laxmi Suwal, Erich H Kisi, Oliver Kirstein, The University of Newcastle, Australia, Australian Centre for Neutron Scattering, Australia, European Spallation Source, Sweden

Tubular Push Conveyor – Functional Analysis and Simulation - Andre Katterfeld, Christian Richter, University of Magdeburg, Germany

DEM Simulation of the Bucket Elevator’s Discharge Considering the Effect of Air Flow - Cong Deng and Yu Li, Wuhan University of Technology

Numerical Study on the Multiphase Flow in the Innovative CAP Cyclone - Ruizhi Jin, Erfan Keshavarzian, Kejun Dong, Sijie Dong, Bo Wang, Kenny Kwok, Ming Zhao, Western Sydney University, Australia, Key Laboratory of Western China's Environmental Systems and Lanzhou University, China, The University of Sydney, Australia

Simulation of a SAG-Mill Using a Coupled CFD-DEM Approach - Lucilla Almeida, Rahul Bharadwaj, Peter Rizkalla, ESSS, Brazil, LEAP Australia

Modelling Slurry Pulps for Grinding Mill Application using a DEM-SPH Modelling Framework - Wei Chen, Alan Roberts, Brad Drinkwater, Bradken Resources Ltd, Australia, The University of Newcastle, Australia

Predictive Optimisation of SAG-Mill Wear Using DEM - Peter Rizkalla, Alex Potapov, Saurabh Sarkar, LEAP Australia, ESSS, Brazil

Coupled Simulations of a Ship Unloading Grab Bucket Utilising Discrete Element Modelling and Multi-Body Dynamics - Samuel  R Lord, David B Hastie, University of Wollongong, Australia

Application of Numerical Modelling and New Spray Technology to Longwall Coal Mining Operations - Jon Roberts, Peter Wypych, Vitold Ronda, David Hastie, University of Wollongong, Australia, Enviromist Pty Ltd, Australia

Transfer Chute Analysis using Continuum Method, DEM and Scale Modelling - Bin Chen, Xinghua Zhao, Minghui Lu, Guannan Qiao, Hainan Wu, Alan Roberts, TUNRA Bulk Solids, Australia, Dalian Huarui Heavy Industry International Co, Ltd, China

Multi-Scale Simulation of the Pellet Rounding During a Spheronization Process - Dominik Weis, Maria Evers, Markus Thommes, Sergiy Antonyuk, University of Kaiserslautern, Germany, Technical University Dortmund, Germany

On the Calibration of DEM Parameters for Abrasive Sliding Wear - Thomas Roessler and Andre Katterfled, University of Magdeburg, Germany

Rolling Friction Estimation of Pellets and Sinters from Image Processing for usage in DEM Simulation - Aman Tripathi, Vimod Kumar, Arpit Agarwal, Saprativ Basu, Samik Nag and Anurag Tripathi, IIT Delhi, India, TATA Steel, India

Influence of Particle Shape in Discrete Element Simulations of Industrial Transfer Chutes - Andrew Grima, Jon Roberts, David Hastie, Stephen Cole, The University of Wollongong, DEM Solutions, UK

Coarse Graining of Adhesive Elasto-plastic DEM Contact Models in Quasi-static Processes - M.Javad Mohajeri, Cees van Rhee, Dingena L.Schott, Delft University of Technology, The Netherlands

Calibration of the Discrete Element Method using an Annular Ring Shear Tester - Corne Coetzee, Stellenbosch University, South Africa

Verification of Dust Particle Behaviour in 2D and 3D Symmetrical Simulations - Luke E. Stone, David B. Hastie, Peter W. Wypych, University of Wollongong, Australia

Calibration of DEM & CFD Coupling Via Comparison with Experimental Data for Drying of Granular Beds - Sam Caldwell, Kenneth Williams, Jie Guo, The University of Newcastle

Retention Capacity of Liquid Bridge and Its Breakage by Vibration - Jian Chen, Kenneth Williams , The University of Newcastle, Australia

Development of a Cohesive DEM Parameters Calibration Protocol for Bulk Materials using Rapid Flow and Low Consolidation Standard Tests - Mohsin Ajmal, Thomas Robler, Michael Carr, Andre Katterfeld, University of Magdeburg, Germany, The University of Newcastle, Australia

Transportation & Logistics

Roy Hill: A Case Study on the Path to 100% Reliability - T. Donohue, N. Williams, S Reid, B. Chen and J. Plinke, TUNRA Bulk Solids, Australia, Roy Hill, Australia

Design, Construction and Commissioning of a Coal Handling Plant at Moolarben Mine, NSW - Craig Sorensen, M Terry, A Bryan, QCC Resources, Australia

Upgrading Rolleston Coal Handling Facility - Lindsay Ford, Russell Jackson, Brad A. Allsopp, Glencore Coal Assets, Australia, WSP Australia

An Agent-based System with Reinforcement Learning for the Train Dispatching Problem - Allan M. C. Bretas, Alexandre Mendes, Martin Jackson, Riley Clement, Claudio Sanhueza, The University of Newcastle, Australia, Hunter Valley Coal Chain, Australia

Dynamic Simulation Model in Coal Port Facility: The Use of a Dynamic Simulation Model to Support the Development of Future Engineering Solutions - Paulo Cardoso de Campos, Ausenco Engineering - APAC, Australia

A Case-study of Heat Transfer in a Ship Loader Operating Coal - Dennis Pomfret, Gian Naldo, Jiahe Shen, Craig Wheeler, The University of Newcastle, Australia, Port Waratah Coal Services, Australia

Fuzzy AHP Approach for Route Selection n Multimodal Transportation: The case of coal industry in Thailand, Kwanjira Kaewfak, Veeris Ammarapala. Japan Advanced Institute of Science and Technology, Japan, Thammasat University, Thailand.

Technology for Clean Bulk Ports - B Velan, Scorpio Engineering, India

Site Tour

A day tour is being organised for Monday July 8th at the Condong Sugar Mill and the Stone and Wood Brewery in Murwillumbah (1 hour drive south from the Gold Coast). The Condong Sugar Mill sits on the banks of the Tweed River and has been crushing cane since 1880. The Condong Sugar Mill tour will consist of a visit to a sugar cane farm and the processing mill.

Following this, a tour of the Stone and Wood facilities including some tastings of the locally brewed beer will finish off the day before heading back to the Gold Coast before the Welcome Reception. This tour will depart from the Mantra on View, Surfers Paradise at approximately 8:30 am and return at approximately 4:00 pm

If you are interested and would like to book your place please contact Please note places are limited so book in fast to avoid missing the tour, costs TBA