Renormalization in 1D Quantum Mechanics contact interactions

Interactive Molecular Dynamics for Nanomechanical and Nanochemical ExperimentsAxel KohlmeyerMolecular Dynamics●Simulate motion of atoms and molecules according to physical models: classical (empirical) or quantum (electrons and/or core)●Microscopic look into the atomic scale;simulated experiment with perfect control.●Connection to macroscopic world throughstatistical mechanics or thermodynamics:=> molecular level interpretation of thermodynamic quantities●Beyond two particles chaotic => coupled differential equations, solved numerically => model and CPU determine time scalesTypical Molecular Dynamics Work Flow●Setup: construct initial geometry, idealized or assembled pieces ●Equilibration: relax and propagate until the desiredthermodynamical state is reached (or close enough)●Production: propagate atoms and record statisticallyrelevant data of system evolution while equilibrium is maintained ●Analysis & Visualization: done “off-line” (i.e. after production)●Statistical analysis to derive structural or thermodynamicalproperties to confirm, guide or predict experiment(s).●Visual inspection of structural changes or “special” eventsStudying 'Rare Events' in Molecular Dynamics●Time scales in MD simulations are limited by the fastest motion => total time that can be studied is restricted.●Size of system is finite => large (local) energy fluctuations rare => events that have (free) energy barriers are often 'impossible'●Various 'biasing methods' exist to make those events possible=> biasing needs to be programmed, cannot “just play around”●Programmed biasing or steering works best for simple moves: 'collective variables' => well defined for statistical analysis●Difficult to study “What would happen if?”-scenarios on the flyEvolution of Interactive MD (IMD)●Origin in steered molecular dynamics (SMD) by adding run-time visualization to monitor the progress of steering●Next step: Interactive determination of steering forces through a pointer device (2d: mouse, 3d: 3d-joystick, 3d-mouse, WiiMote)●Then: better visual feedback with stereo displayeven better with 'immersive visualization', e.g. CAVE●Full IMD framework with support for haptic devicesadding force feedback to 3d tracking => VMD●Limited adoption due to cost and disruptive nature (VR facility)Interactive MD Applications Examples●Education and Outreach:Unique experience through immersive visualizationand force feedback allows students to “grasp” MD simulations●Simulation Monitoring:Visualization can be connected to ongoing production run●Simulation Preparation:Components of an MD simulation system can be interactivelyrearranged (“sculpting”) as needed while close to equilibrium●Nano-mechanical or -chemical experimentsThe IMD Infrastructure in VMDMD Engine:NAMD,Gromacs,HOOMD-blue,LAMMPS, ...Visualization& VR Client:VMDCoords FeedbackTrackerForcesVR Server:VRPN(-ICMS),Haptic deviceSocketSocketTime Scale Issues with IMDSimulated System:●Atom velocity: ~100 m/s●MD Time step: ~10-15 sTime and length scales of simulation & visualization are coupled Typical parameters for a smooth IMD configuration:Tangible System:●Compute time: ~1 ms / step●Atom movement: ~10-10 m / s Newton's second law: F = m a=> faster running MD=> less IMD force needed=> objects appear to be lighterTo move large object:=> run MD faster (parallel,GPU)=> or scale applied IMD force=> or change particle massMore Time Scale Issues with IMD●How realistic should an IMD simulation/visualization be?If too large IMD force, too small particle mass => unphysicalmay be tolerated for educational use, unacceptable for research●Local movements (solvent) limit length of time step●Compute capability limits speed of MD code●Visualization update rate limits position update frequency=> At higher MD speed, less frequent IMD position updates => position data becomes more “noisy”, need denoising filter●What if I want to look at “slow” processes? Move large objects?Recorded IMD Demos with “Falcon” Controller●“Stick the buckyballs intothe nanotube demo●Virtual vacuum AFM demowith 3 types of LJ particlesRevived Interest in Interactive MD●A smooth IMD visualization needs about 20-30 frames/s●Significant compute power for fast MD on all but the smallest systems●A powerful graphics workstation with stereo capability is required=> a dedicated and expensive facility was needed that few locations could afford and that would require to schedule access ahead of time ●3d screens affordable (3d-TVs, Scanline polarized LCD)●High performance graphics with 3d capability available (games)●Multi-core CPUs and GPUs turn workstations into clusters●Affordable controllers (Falcon (gaming), smartphones (6DOF))VRPN and VMD Enhancements●Support in VRPN for Novint Falcon as haptic 3DOF device●Implement Tracker and Button classes as sending devices●Implement ForceDevice class as receiving device●Use libnifalcon ( ) to access Falcon●Implement damping scheme for smooth force constraint updates(force update in device at 1000Hz, update from VMD less frequent)●Enhancements in VMD●Support for enforced TCP only communication with VRPN server forusing remote visualization facility via VirtualGL (LRZ Munich)●Support for whole residue mode with “tug” toolLAMMPS Enhancements●OpenMP (LAMMPS-ICMS) and GPU (GPULAMMPS) acceleration for non-bonded interactions=> faster MD for smaller (OpenMP) or larger (GPU) systems●Improvements in IMD module (fix imd):●Listening for IMD force input in separate thread.No more need to “drain” all incoming IMD communication data●Sending of coordinate data in separate threadNo more need to wait when large IMD data is sent over slow link●Addition of Savitzky-Golay filtering of coordinate dataDenoises coordinate updates with large Δt with minimal distortionIMD Appliance Concept●Combines:●Multi-core/CPU/GPU compute●Stereo capable visualization●3d display●Haptic device●Software●No special facility needed●Commodity components●Kiosk mode for educationPerspectives●Advances in GPU acceleration will expand applicability●GPU acceleration more effective in compute intense models=> nano-mechanics (Tersoff, Stillinger-Weber, AIREBO)=> nano-chemistry (Reaxx)●More approximate models for large changes(temporary coarse graining)●More experiments with example applications or demos needed ●IMD protocol expansions and optimizations●VRPN-ICMS improvements (multi-Falcon support, alternate grip)References●VMD: /Research/vmd●LAMMPS: /LAMMPS-ICMS (code gets merged to LAMMPS when stable): /site/akohlmey/software/lammps-icms●VRPN: /Research/vrpn/VRPN-ICMS (code will be merged into VRPN when stable): /site/akohlmey/software/vrpn-icms●GPULAMMPS (GPU acceleration with CUDA for LAMMPS):/p/gpulammps/●Michael L. Klein (freedom and funding, NSF CHE 09-46358)●John Stone, Klaus Schulten (VMD and much more)●Steve J. Plimpton, Paul S. Crozier and many others (LAMMPS)●Russ Taylor (VRPN), Kyle Machulis (libnifalcon)●Tom Anderson, Brandon Williams, Novint, (free Falcons) ...and...●Greg & Gary Scantlen, Creative Consultants,(contacts, encouragement, perseverance, 3D-buckyballs) Make sure you try out the “Nano Dome”, Booth 29/30.Acknowledgements。

简-马里-莱恩（Jean-Marie Lehn）简-马里-莱恩（Jean-Marie Lehn）教授1939年出生于法国罗塞姆。

1963年获得法国斯特拉斯堡大学理学博士学位，随后在哈佛大学从事博士后研究，主要工作室维生素B12的全合成。

回到斯特拉斯堡后，他开始在有机化学和物理化学的交叉前沿领域开展研究工作，后来将一部分研究兴趣放到生物学过程上。

1968年，他合成了一种笼状的分子，可以与多种金属离子形成内包复合物。

以此为开端，他开始研究“分子识别”的化学基础，也就是受体分子识别和选择性绑定底物的方式，这是许多生物学过程的基础。

1970年，他成为斯特拉斯堡路易斯－巴斯德大学化学系教授；1979成为巴黎法兰西学院教授。

1987年，Lehn教授凭借在此领域的研究工作与D.J. Cram和C.J. Pedersen一起分享了诺贝尔化学奖。

法国科学院院士。

莱恩（Lehn）教授的工作开创了一个全新的化学研究领域，他称之为“超分子化学”，他也凭借在此领域的杰出工作被称为“超分子化学之父”。

超分子化学主要研究两个或两个以上的化学分子通过分子间作用力形成复杂组装体的过程和性质，而传统的分子化学研究的是原子通过共价键作用形成的分子的性质。

他的研究从分子识别拓展到了超分子催化和传输过程，后来也拓展到超分子电子学和光学分子器件的设计和构建。

因此，他的研究发展主线主要关注合适的组分分子通过自组织自发组装形成可编程化的具有确定结构的超分子组装体。

最近，通过引入可逆的共价键给超分子体系引入了动态变化的特征，他创立了“组合动态化学”并发展成自适应化学。

莱恩（Lehn）教授迄今为止已经发表了800多篇学术论文。

他是世界各地多个学术组织的会员，包括法国科学院院士，美国国家科学院外籍院士，美国艺术和科学院外籍荣誉会员，中国科学院外籍院士等。

他获得了包括诺贝尔化学奖在内的许多国际性的大奖和荣誉。

附件1、2----附件1、超分子化学概要宇宙在进化的过程中通过自组织生成了越来越复杂的直至有生命和思想的物质。

附件6作者姓名：卢滇楠论文题目：温敏型高分子辅助蛋白质体外折叠的实验和分子模拟研究作者简介：卢滇楠，男，1978年4月出生, 2000年9月师从清华大学化工系生物化工研究所刘铮教授，从事蛋白质体外折叠的分子模拟和实验研究，于2006年1月获博士学位。

博士论文成果以系列论文形式集中发表在相关研究领域的权威刊物上。

截至2007年发表与博士论文相关学术论文21篇，其中第一作者SCI论文9篇（有4篇IF>3），累计他引20次（SCI检索），EI收录论文14篇（含双收），国内专利1项。

中文摘要引言蛋白质体外折叠是重组蛋白质药物生产的关键技术，也是现代生物化工学科的前沿领域之一，大肠杆菌是重要的重组蛋白质宿主体系，截止2005年FDA批准的64种重组蛋白药物中有26种采用大肠杆菌作为宿主体系，目前正在研发中的4000多种蛋白质药物中有90%采用大肠杆菌为宿主表达体系。

但由于大肠杆菌表达系统缺乏后修饰体系使得其生产的目标蛋白质多以无生物学活性的聚集体——包涵体的形式存在，在后续生产过程中需要对其进行溶解，此时蛋白质呈无规伸展链状结构，然后通过调整溶液组成诱导蛋白质发生折叠形成具有预期生物学活性的高级结构，这个过程就称之为蛋白质折叠或者复性，由于该过程是在细胞外进行的，又称之为蛋白质体外折叠技术。

蛋白质体外折叠技术要解决的关键问题是避免蛋白质的错误折叠以及形成蛋白质聚集体。

目前本领域的研究以具体技术和产品折叠工艺居多，折叠过程研究方面则多依赖宏观的结构和性质分析如各类光谱学和生物活性测定等，在研究方法上存在折叠理论、分子模拟与实验研究结合不够的问题，这些都不利于折叠技术的发展和应用。

本研究以发展蛋白质新型体外折叠技术为目标，借鉴蛋白质体内折叠的分子伴侣机制，提出以智能高分子作为人工分子伴侣促进蛋白质折叠的新思路，即通过调控高分子与蛋白质分子的相互作用，1）诱导伸展态的变性蛋白质塌缩形成疏水核心以抑制蛋白质分子间疏水作用所导致的聚集，2）与折叠中间态形成多种可逆解离复合物，丰富蛋白质折叠的途径以提高折叠收率。

第1篇Introduction:Quantum entanglement, one of the most intriguing and challenging concepts in quantum mechanics, has puzzled scientists for over a century. This phenomenon, where particles become interconnected regardless of the distance separating them, has far-reaching implications for our understanding of the universe and potential technological advancements. In this interview question, we will delve into the scientific principles of quantum entanglement, its experimental validations, and the potential applications it may offer in the future.Section 1: Introduction to Quantum Entanglement1.1 Definition of Quantum Entanglement:Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles become linked in such a way that the quantum stateof each particle cannot be described independently of the state of the others, even when the particles are separated by large distances.1.2 Historical Background:The concept of quantum entanglement was first introduced by Albert Einstein, Boris Podolsky, and Nathan Rosen in 1935 in their famous paper titled "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?" This paper, often referred to as the EPR paradox, sparked a debate on the completeness and interpretation of quantum mechanics.1.3 Quantum Mechanics and Classical Mechanics:Quantum entanglement is a quintessential feature of quantum mechanics, which fundamentally differs from classical mechanics. In classical mechanics, the state of a system is determined by the positions and velocities of its particles, while in quantum mechanics, particles exist in a probabilistic state until measured.Section 2: The Principles of Quantum Entanglement2.1 Superposition:Superposition is a fundamental principle of quantum mechanics, which states that a quantum system can exist in multiple states simultaneously. This principle allows particles to be entangled, as their combined state cannot be described by the state of each particle individually.2.2 Non-locality:Non-locality is the idea that quantum entangled particles can instantaneously affect each other's states, regardless of the distance separating them. This concept challenges the principle of locality in classical physics, which dictates that no physical influence can travel faster than the speed of light.2.3 Bell's Inequality:John Bell proposed an inequality in 1964 that sets a limit on the amount of non-local correlations that can exist between particles in classical physics. Quantum entanglement violates Bell's inequality, providing experimental evidence for the non-local nature of quantum mechanics.Section 3: Experimental Validations of Quantum Entanglement3.1 Alain Aspect's Experiment:In 1982, Alain Aspect conducted a groundbreaking experiment that confirmed the violation of Bell's inequality, providing strong evidence for quantum entanglement and non-locality. His experiment involved measuring the polarizations of photons emitted from a source and showed that the correlations between the photons exceeded the limits set byBell's inequality.3.2 Quantum Key Distribution (QKD):Quantum key distribution is a secure communication protocol that leverages the principles of quantum entanglement. It allows two parties to share a secret key with the guarantee that any eavesdropping can be detected. QKD has been experimentally demonstrated over long distances, such as satellite-based communication links.3.3 Quantum Computing:Quantum entanglement is a crucial resource for quantum computing, which aims to solve complex problems much faster than classical computers. Quantum computers use qubits, which are entangled particles, to perform calculations by exploiting superposition and interference.Section 4: Implications for Future Technologies4.1 Quantum Communication:Quantum entanglement has the potential to revolutionize communication by enabling secure, long-distance communication using QKD. This technology could be crucial for establishing secure networks and protecting sensitive information.4.2 Quantum Computing:Quantum entanglement is essential for the development of quantum computers, which have the potential to solve complex problems in cryptography, material science, and optimization. Quantum computers could also simulate quantum systems, leading to new discoveries in chemistry, physics, and biology.4.3 Quantum Sensing:Quantum entanglement can be used to enhance the sensitivity of quantum sensors, which have applications in various fields, including gravitational wave detection, quantum metrology, and precision measurement.Conclusion:Quantum entanglement, with its fascinating principles and experimental validations, has the potential to reshape our understanding of the universe and enable groundbreaking technological advancements. From secure communication to powerful quantum computers, the implications of quantum entanglement are vast and far-reaching. As scientists continue to explore this intriguing phenomenon, we can expect even more exciting developments in the field of quantum physics and its applications.第2篇Introduction:Quantum entanglement, one of the most fascinating and enigmatic phenomena in the realm of physics, has intrigued scientists and philosophers alike for decades. This interview delves into the depths of quantum entanglement, exploring its origins, implications, and potential applications. Dr. Emily Newton, a renowned quantum physicist, shares her insights and experiences in this field.Part 1: The Basics of Quantum EntanglementQuestion 1: Can you explain what quantum entanglement is and how it differs from classical entanglement?Dr. Newton:Quantum entanglement is a phenomenon in which two or more particles become interconnected, such that the quantum state of one particle instantaneously correlates with the state of another, regardless of the distance separating them. This correlation persists even when the particles are separated by vast distances, which defies the principles of classical physics.In classical entanglement, such as the entanglement of a pair of dice, the outcome of one die is independent of the other. If you roll a six on one die, it does not affect the outcome of the other die. However, in quantum entanglement, the particles are not independent; their quantum states are correlated in such a way that measuring one particle's state instantly determines the state of the other particle, regardless of the distance between them.Question 2: How was quantum entanglement discovered, and what were the early reactions to this phenomenon?Dr. Newton:Quantum entanglement was first predicted by Albert Einstein, Boris Podolsky, and Nathan Rosen in their famous EPR paradox paper in 1935.They proposed a thought experiment involving two entangled particlesthat seemed to violate the principle of locality, which states that no information can travel faster than the speed of light.The initial reaction to the EPR paradox was skepticism, with Einstein famously dismissing quantum entanglement as "spooky action at a distance." However, subsequent experiments, such as those conducted by John Bell in the 1960s, provided strong evidence in favor of quantum entanglement, leading to a paradigm shift in our understanding of the quantum world.Part 2: The Mechanics of Quantum EntanglementQuestion 3: What are the key factors that contribute to the formation of entangled particles?Dr. Newton:The formation of entangled particles is a result of their interaction during the process of measurement or preparation. For example, when two particles are created together in an entangled state, their quantum states become correlated due to their shared history. This correlationis a fundamental aspect of quantum mechanics and cannot be explained by classical physics.Another way to create entangled particles is through a process called entanglement swapping, where two particles are initially entangled with a third particle, and then the third particle is separated from thefirst two. This results in the first two particles becoming entangled with each other, even though they have never interacted directly.Question 4: Can you explain the concept of quantum superposition and how it relates to entanglement?Dr. Newton:Quantum superposition is the principle that a quantum system can existin multiple states simultaneously until it is measured. This is analogous to a coin spinning in the air, which can be either heads or tails until it lands on one side.In the context of entanglement, superposition plays a crucial role. When two particles are entangled, their combined quantum state is a superposition of the individual states of each particle. This means that the particles can exhibit non-local correlations that are not determined until a measurement is made.Part 3: The Implications of Quantum EntanglementQuestion 5: How does quantum entanglement challenge our understanding of the universe?Dr. Newton:Quantum entanglement challenges our classical understanding of the universe in several ways. Firstly, it defies the principle of locality, which has been a cornerstone of physics for centuries. The idea that particles can instantaneously influence each other across vast distances suggests that the fabric of space-time may not be as fixed as we once thought.Secondly, quantum entanglement raises questions about the nature of reality itself. If particles can be correlated in such a way that their states are instantaneously connected, it challenges the idea that objects have definite properties independent of observation.Question 6: Are there any practical applications of quantum entanglement?Dr. Newton:Yes, there are several potential applications of quantum entanglement. One of the most promising is in quantum computing, where entangled particles can be used to perform complex calculations at speeds unattainable by classical computers. Quantum entanglement is also essential for quantum cryptography, which can be used to create unbreakable encryption methods.Moreover, entanglement has been used in quantum teleportation, where the state of a particle can be transmitted instantaneously from one location to another, potentially leading to new communication technologies.Conclusion:Quantum entanglement remains one of the most intriguing and challenging phenomena in physics. Dr. Emily Newton's insights into the mechanics and implications of this phenomenon provide a deeper understanding of the quantum world and its potential applications. As we continue to explore the mysteries of quantum entanglement, we may uncover new ways to harness its power and reshape our understanding of the universe.第3篇IntroductionQuantum entanglement, one of the most intriguing and mysterious phenomena in the field of quantum mechanics, has captured the imagination of scientists and the public alike. This question invites candidates to delve into the concept of quantum entanglement, its underlying principles, experimental demonstrations, and the potential implications it holds for future technology.Part 1: Introduction to Quantum Entanglement1.1 Definition and Basic PrinciplesQuantum entanglement refers to a phenomenon where two or more particles become interconnected in such a way that the quantum state of each particle cannot be described independently of the state of the others, even when they are separated by large distances. This correlation persists regardless of the distance between the particles, which challenges our classical understanding of locality and separability.1.2 Historical ContextThe concept of quantum entanglement was first introduced by Albert Einstein, Boris Podolsky, and Nathan Rosen in their famous EPR paradox paper in 1935. They described entanglement as "spooky action at a distance," suggesting that it defied the principles of local realism. However, subsequent experiments and theoretical developments have confirmed the reality of entanglement.Part 2: Theoretical Underpinnings of Quantum Entanglement2.1 Quantum SuperpositionQuantum superposition is a fundamental principle of quantum mechanics that allows particles to exist in multiple states simultaneously. This principle is crucial for understanding entanglement, as it enables particles to become correlated in a way that is not possible inclassical physics.2.2 Quantum Correlation and EntanglementQuantum entanglement arises from the non-classical correlations between particles. When particles become entangled, their quantum states become linked, and the state of one particle instantaneously influences the state of the other, regardless of the distance separating them.2.3 Bell's TheoremJohn Bell formulated a theorem in 1964 that demonstrated the incompatibility of quantum mechanics with local realism. Experimentsthat violate Bell's inequalities have confirmed the existence of quantum entanglement and its non-local nature.Part 3: Experimental Demonstrations of Quantum Entanglement3.1 Bell Test ExperimentsBell test experiments have been conducted to test the predictions of quantum mechanics and to demonstrate the non-local nature of entanglement. These experiments involve measuring the properties of entangled particles and analyzing the correlations between them.3.2 Quantum Key Distribution (QKD)Quantum Key Distribution is a protocol that uses quantum entanglement to securely transmit cryptographic keys. It takes advantage of theprinciple that any attempt to intercept the entangled particles will disturb their quantum state, alerting the communicating parties to the presence of an eavesdropper.3.3 Quantum TeleportationQuantum teleportation is the process of transmitting the quantum state of a particle from one location to another, without the particle itself traveling through the space between them. This phenomenon has been experimentally demonstrated and has implications for quantum computing and communication.Part 4: Implications for Future Technology4.1 Quantum ComputingQuantum computing, which relies on the principles of quantum mechanics, has the potential to revolutionize computing by solving certain problems much faster than classical computers. Quantum entanglement plays a crucial role in quantum computing, as it allows for the creation of qubits that can exist in multiple states simultaneously, enabling parallel processing.4.2 Quantum CommunicationQuantum communication utilizes the principles of quantum entanglement and superposition to achieve secure communication and distributed computing. Technologies like QKD and quantum teleportation are expected to transform the field of secure communication and enable new forms of data transmission.4.3 Quantum Sensors and MetrologyQuantum sensors and metrology techniques leverage the precision and sensitivity of quantum entanglement to measure physical quantities with unprecedented accuracy. This has applications in fields such as precision navigation, gravitational wave detection, and quantum simulation.ConclusionQuantum entanglement, with its counterintuitive nature and profound implications, remains a captivating and challenging subject in the field of quantum mechanics. As scientists continue to explore and harness thepower of entanglement, we can expect to see significant advancements in technology, leading to new possibilities in computing, communication, and metrology. This question has provided an opportunity to delve into the fascinating world of quantum entanglement and its potential future impact on society.。

高二英语科学家名称单选题20题1.Who is known for inventing papermaking?A.ConfuciusB.GalileoC.Cai LunD.Newton答案：C。

蔡伦发明了造纸术。

孔子是思想家教育家，伽利略是天文学家和物理学家，牛顿是物理学家和数学家。

2.Which ancient scientist is famous for his contributions to astronomy?A.Zhang Hengo TzuC.PlatoD.Aristotle答案：A。

张衡对天文学有很大贡献。

老子是思想家，柏拉图和亚里士多德是哲学家。

3.Who is renowned for his medical achievements in ancient times?A.HippocratesB.SocratesC.PythagorasD.Euclid答案：A。

希波克拉底在古代以医学成就闻名。

苏格拉底是哲学家，毕达哥拉斯是数学家，欧几里得是数学家。

4.Which ancient scientist is associated with the invention of the seismograph?A.Bi ShengB.Zhuge LiangC.Zhang HengD.Sima Qian答案：C。

张衡发明了地动仪。

毕昇发明活字印刷术，诸葛亮是政治家军事家，司马迁是史学家。

5.Who is known for his contributions to mathematics in ancient Greece?A.EuclidB.Alexander the GreatC.SolonD.Herodotus答案：A。

欧几里得对古希腊数学有贡献。

亚历山大大帝是军事家，梭伦是政治家，希罗多德是历史学家。

6.Who is known for his theory of relativity?A.NewtonB.EinsteinC.DarwinD.Franklin答案：B。

The research in MAS concentrates on the qualitative, numerical and computational aspects of mathema-tical models arising in a wide range of applications within the Dutch society.Particular attention is gi-ven to models describing continuum processes.As examples we mention freefluid and porous mediaflow,chemical reactions in the atmosphere and cir-cuit analysis.The applications are combined into two extensive programmes or themes,each contai-ning a number of characteristic projects.They are accounted for in detail in the theme descriptions of MAS1and MAS2.New developments include the projects MAS2.1(Computationalfluid dynamics,a collaboration with MARIN)and MAS2.7(Mathe-matics of Finance).Preliminary contacts have been made with TNO-TPD and across the border with GMD in Germany.It is expected that new projects will emerge from these contacts.In the midst of much applied work,MAS conti-nues to contribute significantly to the scientific de-velopment in the areas of qualitative,numerical and computational methods for partial differential equati-ons.The number of papers appeared in international journals is certainly satisfactory,and withfive PhD theses MAS contributes substantially to the scientific output of the CWI.Separately from the themes,the Dynamical Sys-tems Laboratory(DSL)operated as an independent unit.During the past years DSL has played a leading role in the software development for bifurcation of equilibria of systems of ordinary differential equa-tions.An extensive description of their activities is given in the DSL contribution.This year was the last year of DSL,which officially ended when Dr.Yu.A. Kuznetsov left the CWI(November1st,1997). MAS is very pleased to have Professor Piet van der Houwen as a CWI Fellow in its ranks.His high level scientific input,interaction with young re-searchers and involvement with several project is very much appreciated.Dynamical Systems Laboratory–DSL-Yu.A.Kuznetsov-V.V.Levitin -J.A.SandersEnvironmental Modelling and Porous Media Re-search–MAS1-J.G.Verwer-C.J.van Duijn-J.Hulshof-P.J.van der Houwen-J.G.Blom-C.Cuesta-M.I.J.van Dijke-G.Galiano-W.Hundsdorfer-J.Koknserstdrager-M.A.A.van Leeuwen-W.M.Lioen-M.van Loon-J.Molenaar-R.J.Schotting-B.P.Sommeijer-E.J.Spee-J.de Vries-P.M.de ZeeuwIndustrial Processes–MAS2-E.H.van Brummelen-S.Cavallar-M.K.C¸amlıbel-M.Genseberger-T.Hantke-P.W.Hemker-J.Hoogland-P.J.van der Houwen-K.Karamazen-M.Kirkilionis-A.de Koeijer-B.Korennserstdrager-W.M.Lioen-P.L.Montgomery-M.Nool-J.Noordmans-O.Penninga-A.van der Ploeg-H.J.J.te Riele-A.J.van der Schaft-J.M.Schumacher-B.P.Sommeijer-W.J.H.Stortelder-J.B.de Swart-N.M.Temme-W.A.van der Veen-D.T.Winter-P.WesselingSecretary:N.MitrovicJ.A.SandersYu.A.KuznetsovV.V.LevitinDuring1997,two versions of CONTENT,1.3and1.4,were released on ftp.cwi.nl in directorypub/CONTENT.Release1.4–December,1997New features:-new class of dynamical systems is supported: differential-algebraic equations(DAEs)Mx’=f(x,p) with possibly singular matrix M;-numerical integration of stiff ODEs and DAEs using RADAU5code;-three-parameter continuation of all codim2bifur-cations of ODEs(cusp,Bogdanov-Takens,genera-lized Hopf,zero-Hopf,and double Hopf);-two-parameter continuation of Hopf bifurcation using the bordered squared Jacobian matrix;-symbolical calculation of derivatives of the4th or-der using the Maple system.Release1.3–August,1997New features:-one-parameter continuation of limit cycles in ODEs;-detection and branch switching at codim1bifurca-tions of limit cycles;-one-parameter continuation offixed points of ite-rated maps;-detection and normal form analysis of codim1bi-furcations of iterated maps;-3D graphic windows;-Staircase window for scalar iterated maps.At the moment,CONTENT completely supportsone-parameter analysis of equilibria and cycles in ODEs and iterated maps.To complete the support of two-parameter analysis of ODEs,one has to imple-ment the continuation of codim1bifurcations of cy-cles(i.e.,fold,period-doubling,and Neimark-Sacker bifurcations),as well as the homoclinic bifurcati-ons of saddle and saddle-node equilibria,and branch switching between them.CONTENT provides the environment to implement all of these continuations. Also,the computation of the remaining normal form coefficients at codim2bifurcations of equilibria has to be implemented in CONTENT(see below).Yu.A.Kuznetsov derived explicit normal form coefficients for the reduced to the central manifold equations for all codim2equilibrium bifurcation of ODEs.A CWI Report is published.Yu.A.Kuznetsov(together with aerts and B. Sijnave,Gent University)developed new algorithms to continue codim1and2bifurcations of equilibria in2and3parameters,respectively.The algorithms were implemented in CONTENT.Yu.A.Kuznetsov(together with A.Champneys (Bristol)and B.Sandstede(Berlin))implemented the homoclinic continuation into AUTO97,the latest version of the continuation/bifurcation software by E.Doedel(Concordia University,Montreal).Now it is the standard part of AUTO.The text of the second edition of the book by Yu.A. Kuznetsov Elements of Applied Bifurcation The-ory has been sent to the Production Departmentof Springer-Verlag in September1997and will be published in1998.E.Doedel(Concordia University,Montreal,Ca-nada)June15–28.The visit was devoted to discussions of new me-thods to continue codim1bifurcations of limit cy-cles.In particular,a new method to continue the period-doubling bifurcation was proposed that combines orthogonal collocation technique with matrix bordering.O.De Feo(Swiss Federal Institute of Technology, Lausanne,Switzerland)September1–30.During the visit,RADAU5method for the numeri-cal integration of ODEs and DAEs was translated from FORTRAN to C and implemented into CON-TENT.A paper on homoclinic bifurcations in a3D food chain model was practicallyfinished.aerts and B.Sijnave(University of Gent, Belgium)June19–22.Bordering methods to continue codim1and2bi-furcation of equilibria were discussed.A proto-type method to continue the Bogdanov-Takens bi-furcation was implemented during the visit.The continuation of all other codim2bifurcations of equilibria in three parameters was implemented la-ter in1997.A.Shilnikov(Institute of Applied Mathematics and Cybernetics,Nizhnii Novgorod,Russia)May30.A lecture was given at CWI on‘A blue-sky cata-strophe model’,demonstrating a new way of a de-struction of a limit cycle.Yu.A.Kuznetsov gave invited lectures on CON-TENT at the International Workshop‘Numerical analysis of Dynamical Systems’,IMA,Minneapo-lis,USA,September15–19,and at the Workshop ‘Hybrid-methods for Bifurcation and Dynamics of Partial Differential Equations’,University of Mar-burg,June8–11.MAS-R9730.Y U.A.K UZNETSOV.Explicit nor-mal form coefficients for all codim2bifurcations of equilibria in ODEs.E.J.D OEDEL,A.R.C HAMPNEYS,T.F.F AIR-GRIEVE,Y U.A.K UZNETSOV,B.S ANDSTEDE,X.-J.W ANG(1997).AUTO97:Continuation and Bifurcation Software for Ordinary Differential Equa-tions(with HomCont).User’s Guide,Concordia University,Montreal,Canada.W.G OVAERTS,Y U.A.K UZNETSOV,B.S IJNAVE (1997).Implementation of Hopf and double Hopf Continuation Using Bordering Methods,Department of Applied Mathematics and Computer Science,Uni-versity of Ghent,Belgium.W.G OVAERTS,Y U.A.K UZNETSOV,B.S IJNAVE (1997).Computation and Continuation of Codimen-sion2Bifurcations in CONTENT,Department of Ap-plied Mathematics and Computer Science,University of Ghent,Belgium.Y U.A.K UZNETSOV(1997).Centre manifold; Codimension-two bifurcations;Equivalence of dyna-mical systems;Homoclinic bifurcations;Hopf bifur-cation;Saddle-node bifurcation.M.H AZEWINKEL (ed.).Encyclopaedia of Mathematics.Supplement Volume I,Kluwer Academic Publishers,The Nether-lands,179–181,190–101,240,293–294,296–297, 444–445.Dr.J.G.Verwer,researcher,theme leader Prof.dr.ir.C.J.van Duijn,researcher,cluster leaderDr.J.Hulshof,advisorProf.dr.P.J.van der Houwen,researcher,CWI fellowDrs.J.G.Blom,researcherMrs.C.Cuesta,Ph.D.studentDrs.M.I.J.van Dijke,Ph.D.studentDr.G.Galiano,postdocDr.W.Hundsdorfer,researcherDrs.J.Kok,researchernser,Ph.D.studentstdrager,Ph.D.studentDr.M.A.A.van Leeuwen,postdocDrs.W.M.Lioen,programmerDr.M.van Loon,postdocDr.J.Molenaar,postdocIr.R.J.Schotting,researcherDr.B.P.Sommeijer,researcherDrs.E.J.Spee,Ph.D.studentDr.J.de Vries,researcherDrs.P.M.de Zeeuw,programmer,till February1The general purpose of this research theme is to develop,analyze and implement mathematical and numerical models for application to complex pro-blems arising in environmental modelling and porous media research.MAS1is particular concerned with ordinary and partial differential equations,descri-bingfluidflow,transport of pollutants and chemical and bio-chemical processes.These differential equa-tions lie at the heart of simulation models used in atmospheric air quality modelling,in surface wa-ter and groundwater water quality modelling,and in porous media research directed for example at en-hanced oil recovery.The research subthemes cover a wide range of scientific activities,ranging from fun-damental mathematical and numerical analysis of differential equations and development of new com-putational techniques for use on vector/parallel and massively parallel computers and heterogeneous net-works(HPCN),to implementation of fully integrated models and application to real life problems.Exten-sive co-operations and contacts are maintained with researchers from the academic world and from the environmental and porous media applicationfields. Externalfinancing comes from a variety of sources, such as industry,special programs from the Nether-lands Organization for Scientific Research,research programs from the European Union and the national HPCN program funded through the Ministry of Eco-nomic Affairs.In1997research was organized in four subthemes:The research concerns the numerical modelling of the long range transport and chemical exchange of atmospheric air pollutants.Within the Netherlandsco-operation has existed with KEMA,NLR,RIVM, TUD,TNO and UU/IMAU.At the international le-vel,two joint papers with CGRER(Center for Global and Regional Environmental Research,Universityof Iowa),have been published in Atmospheric Envi-ronment(See Sandu et al.).The CWI group is also active within the European network GLOREAM and among others involved in the organization of an In-ternational Conference on Air Pollution in Paris in 1998.January23,1998,Edwin Spee will defend his Ph.D.Thesis Numerical Methods in Global Trans-port Models at the University of Amsterdam.Two new Ph.D.students have recently joined the group, viz.Debby Lanser and Boris Lastdrager.In1997 MAS1worked on the following projects:RIFTOZ–The technique of data-assimilation has been examined for improving results of model simulations by usage of actual measurements.A special implementation of an extended Kalmanfilter has been shown promising,see Report MAS-R9702 for details.The project forms part of an EU project in which CWI has been active through a subcon-tract with TUD.At CWI the project has now been terminated with the departure of Dr.M.van Loonto TNO.The Kalmanfilter will be further tested by TNO for use in their dispersion model LOTOS. LOTOS–Here the objective is to develop a regio-nal,three-dimensional,long term ozone simulation model.This LOTOS model should replace at due time an existing regional forecasting model in use at TNO.The model is developed in co-operation with TNO researchers.At TNO the focus lies on physi-cal,meteorological and chemical aspects.The CWI research focuses on the design of the mathematical model for a so-called hybrid(terrain following and pressure based)coordinate system and,in particular, of tailored numerical algorithms and implementa-tions on super and parallel computers.The project is part of the TASC project‘HPCN for Environ-mental Applications’which is funded by the Dutch HPCN program.At the end of1997the project was halfway.Afirst running operational prototype im-plemented at CWI has recently been transferred to TNO.Research details are found in the reports MAS-N9701,R9717.NCF–This one-year project is linked with the LOTOS project and concerns aspects of massive parallelism,in particular for T3E implementations. Special attention has been given to the question to which extent massive(meteo)I/O can degrade the parallel performance of models used in atmospheric simulations.Results will be reported early1998. Support is provided by the NCF/Cray University Grant program.The project lasts until April next year.Early1997the Report MAS-R9702wasfinish-ed.This publication concerns research in a similar NCF project terminated in February,1997.CIRK–This Ph.D.project has been terminatedat the end of1997with the departure of Drs.Edwin Spee.He will defend his Thesis at the Universityof Amsterdam on January23,1998.The project is similar to the LOTOS project,but here the particu-lar objective was to develop numerical algorithms for use in3D models for the whole of the global troposphere/stratosphere.In this last year we have worked on various aspects of a Rosenbrock method (see Report MAS-R9717),including stiff chemis-try integration and a factorization approach within the Rosenbrock framework.The factorization idea was investigated to provide an alternative for time or operator splitting.A second main activity has been the validation of various advection schemes in a real life radon experiment,using analyzed windfields from the ECMWF(see Report MAS-R9710).Sup-port for this project was obtained from the RIVM and very fruitful scientific co-operation has existed with IMAU/UU.This co-operation will continue in a following project,planned for the next three years. The new project is centered around the existing mo-del TM3.With support from SWON two postdocs will be hired for algorithmic and parallel software research.GOA–This activity concerns a new Ph.D.project on the‘Analysis and Validation of Operator Split-ting in Air Quality Modeling’.This project has been granted by GOA,the Netherlands Geoscien-ces Foundation.It started September1,1997with the employment of Ir.Debby Lanser.Afirst article on the analysis of Strang-splitting for PDEs of the advection-diffusion-reaction type is already in prepa-ration.SWON–A second new project Ph.D.project started December1,1997with the employment of Drs.Boris Lastdrager.This project has been granted by SWON and concerns‘Sparse Grid Methods for Time-Dependent PDEs’.Atmospheric transport-chemistry problems provide a highly useful applica-tion for sparse-grid research.The project is a joint activity between MAS1and MAS2(Dr.ir.B.Ko-ren).The research concentrates on the design of parallel numerical methods for the simulation of water pol-lution(calamitous releases),the marine eco-system,dispersion of river water,sediment transport,etc. Our activities in1997included:HPCN–In1996we started the development of a special purpose3D transport model based onfinite difference space-discretization and unconditionally stable,implicit time-discretization.In1997we ana-lyzed an iterative approach for solving the implicit relations.This iteration process is based on approxi-mate factorization such that only one-dimensionally implicit,linear systems occur in the algorithm.Inco-operation with C.Eichler-Liebenow from the University of Halle,the convergence region of the iteration method and its effect on the overall stabi-lity of the integration method has been analyzed, see Report MAS-R9718.Furthermore,we started the development of tools for domain decomposition with domains of varying grid resolutions.Part of the research was carried out within the research con-sortium TASC,with support from the Dutch HPCN programme.SWEM–The velocityfield needed by transport models either is read from inputfiles or is computed simultaneously with the computation of the pollu-tant concentrations by means of a hydrodynamical model.In view of the complicated data structures in-volved,we decided to focus on the second approach, because the hydrodynamical model can be designed such that it uses the same data structures as the trans-port model.Such an approach is justified,because the underlying partial differential equations are to a large extent identical.By choosing the same type of spatial and temporal discretizations,the same decom-position in domains with the same resolutions,and the same stepsizes in both algorithms,we achieve that the data structures are exactly the same.Since the transport solver is designed and tuned with paral-lel computer systems in mind,the velocityfield sol-ver will also be tuned to parallel computer systems. Moreover,each velocity-field-solver step can be per-formed in parallel with the corresponding transport-solver step.In1997afirst analysis of the underlying numerical model has been performed.This subtheme coordinates a number of research ac-tivities in analysis of nonlinear partial differential equations and in mathematical modelling offlow and transport through porous media.The character of the research ranges from very applied to theoretical.An example of an applied activity is the NAM-project, where software was developed to study the mixingof gases in underground reservoirs.An example of a theoretical activity is the collaboration withH.W.Alt(Universit¨a t Bonn),which involves a de-tailed study of a free boundary problem with a cusp. This project participates in the interaction platform ‘Nonlinear Transport Phenomena in Porous Media’, which brings together researchers from TUD,RUL, LUW,RIVM and CWI,and which is supported by the NWO Priority Programme‘Nonlinear Systems’. There are also numerous international contacts.The scientific output in1997includes two Ph.D.theses: Problems in Degenerate Diffusion by Mark Peletier and Multi-Phase Flow Modeling of Soil Contamina-tion and Soil Remediation by Rink van Dijke.PDE RESEARCH–Nonlinear PDEs arising in models for porous mediaflow form the backbone of this project.Particular attention was given to sys-tems consisting of a convection-diffusion equation coupled with an ordinary differential equation.The general case,in which the ODE is in the time vari-able,is treated in the thesis of M.A.Peletier.A par-ticular case,where the ODE is in a space coordinate, appears in a model for salt uptake by mangroves,see Report MAS-R9728.This leads to non-local con-vection,which is shown to imply non-uniqueness.A second activity involves the collaboration Alt-Van Duijn.In a series of papers they study the behaviour of the interface between fresh and salt groundwater in the presence of wells.The interface appears asa free boundary in an elliptic problem.Depending on the pumping rate of the wells,a singularity de-velops in the free boundary in the form of a cusp.A detailed local analysis of the free boundary near such a cusp is presented in Report MAS-R9703.FTPM–This project deals with density drivenflow in porous media.In1997research concentrated on brine transport problems that are related to high-level radioactive waste disposal in salt domes.High salt concentrations give rise to nonlinear transport phenomena such as enhancedflow due to volume (compressibility)effects and the reduction of hydro-dynamical dispersion due to gravity forces.Mainly (semi)analytical techniques(similarity and V on Mi-ses transformations)were used to study the volume effects,see Report MAS-R9724.Report AM-R9616 (Brine transport in porous media:Self-similar solu-tions)has been accepted for publication in Advances in Water ing experimental data of Dr.H.Moser(Technische Universit¨a t Berlin)we also ve-rified a nonlinear dispersion theory proposed by Dr. S.M.Hassanizadeh(Delft University of Technology), which includes the effect of dispersion reduction due to local high salt concentrations.The nonlinear the-ory is in excellent agreement with the experimentalresults,see Report MAS-R9734.We further consi-dered the interface between fresh and salt groundwa-ter in heterogeneous media.This subject is relatedto salt water intrusion problems in coastal aquifers. The interface approximation can be justified when the width of the mixing zone between thefluids is small compared to the vertical extension of the aqui-fer.We studied the resulting set of interface equa-tions numerically,using a moving mesh Finite Ele-ment Method.Moreover,several simplified Dupuit problems were studied and the results were compa-red with FEM solutions,see Report MAS-R9735. NAM–This project deals with the mathematical modelling of gas injection.The dispersion is studied for gas injection into a reservoir.The aim is to un-derstand and quantify the relevant physical processes that lead to mixing of injected gas with residual gas in old reservoirs.The project is sponsored by the NAM(Nederlandse Aardolie Maatschappij).In co-operation with the Faculty of Mining and Petroleum Engineering of the Delft University of Technology a numerical model is being developed at CWI to study the mixing of the gases in detail.NOBIS–Within this project we study soil reme-diation anic contaminants may be removed from the soil either by pumping methods or by injecting air,which enhances biodegradation and volatilization.The correspondingflow of groundwa-ter,organic contaminant and air is described using multi-phaseflow models.Air injection into ground-water(air sparging)in a horizontally layered medium has been studied in Report MAS-R9729.Accurate numerical simulations of the full transient two-phase flow equations were carried out and an almost ex-plicit solution for the steady state airflow just below a less permeable soil layer was derived.The latter solution showed almost perfect agreement with the numerical results when heterogeneity of the layers was increased.To model pumping of a lens of light organic liquid from an aquifer,multi-phase seepage face conditions were applied at the well boundary (Report MAS-R9725).For two different geome-tries of the lens similarity solutions provided good approximations of the removal rate and the location of the remaining contaminant as a function of time. The above results and other work on behaviour ofa lens of organic contaminant and on air sparging have been gathered in Rink van Dijke’s Ph.D.thesis:‘Multi-phaseflow modeling of soil contamination and soil remediation’,which was defended at Wage-ningen Agricultural University on December5,1997. NWO-NLS–This is the Ph.D.project‘Mathemati-cal Analysis of Dynamic Capillary Pressure Relati-ons in Porous Media Flow’.It started in November 1997,with the employment of C.M.Cuesta.It is supported by the NWO Priority Programme‘Nonli-near Systems’.The aim is to study PDEs with higher order mixed derivatives.Such equations arise in mo-dels for unsaturated groundwaterflow,taking into account dynamic capillary pressure.In1997two different subjects have been studied. Report MAS-R9721contains the results of an inves-tigation to the stability of approximate factorization for-methods.Approximate factorization seems for certain multi-space dimensional PDEs a viable alter-native to time-splitting as a splitting error is avoided. The investigation,however,has revealed limitations of the approximate factorization technique with re-gard to numerical stability.The second subject con-cerns RKC(Runge-Kutta-Chebyshev),an explicit time integrator specifically suitable for multi-space dimensional parabolic PDEs.In RKC the stability limitation inherent in explicit methods is greatly re-duced by the use of a three-step Chebyshev recur-sion.The current study has specifically dealt with the development of a production-grade code for non-experencied users.The work has been carried outin co-operation with Prof.L.Shampine,University of Dallas.Details are given in Report MAS-R9715. This report has been accepted for publication in the Journal of Computational and Applied Mathematics. Mini-symposium on Numerical Analysis,Wage-ningen,April3–anizer:P.M.de Zeeuw. Speakers:W.Hundsdorfer(Stability of the Doug-las Splitting Method),E.J.Spee(Advectieschema’s op een Bol voor Atmosferische Ttransport Model-len).Meeting of the Steering Committee of the ESF-Programme‘Free Boundary Problems,Theory and Applications’,CWI,anizer:C.J.van Duijn.TASC Symposium7,CWI,anizers: J.G.Verwer and J.Kok.Speakers:P.J.H.Builtjes (MEP-TNO)(Atmospheric Transport-chemistry Modelling and HPCN),J.G.Blom(LOTOS,a3D Atmospheric Air Pollution Model),J.Kok(Por-ting Atmospheric Transport-Chemistry Software to the NEC SX–4),K.Dekker(TUD)(Modification of Flow Fields to Recover the Property of Divergence Freedom),G.S.Stelling(WL)(NonhydrostaticPressure in Free Surface Flows)and B.P.Som-meijer(Recent Progress in an Implicit Shallow Water Transport Solver).Colloquium‘Flow and Transport in Porous Me-dia’,CWI,September10.Speakers:G.Dagan (Tel-Aviv)and S.E.A.T.M.van der Zee(LUW). Organizers:R.J.Schotting and C.J.van Duijn. TASC Symposium8(‘HPCN-Platformdag’),CWI, anizers:J.G.Verwer andJ.Kok.Speakers:J.G.Verwer(Het TASC Pro-ject HPCN voor Milieutoepassingen),M.van Loon(MEP-TNO)(Langetermijnsimulatie van Ozon),J.G.Blom(Rekenen aan Ozon),B.P.Som-meijer(Simulatie van Transport in Ondiep Water), E.A.H.V ollebregt(TUD)(Parallelle Software voor Stromings-en Transportmodellen)and G.S.Stel-ling(WL)(Simulatie van Afvalwaterlozingen). Mini-symposium on Partial Differential Equati-ons at SciCADE97–International Conference on Scientific Computation and Differential Equations, Grado,September15–anizer:J.G.Ver-wer.Speakers:K.Dekker(TUD)(Parallel GM-RES and Domain Decomposition),W.Hundsdor-fer(Trapezoidal and Midpoint Splittings for Initial Boundary-value Problems),B.P.Sommeijer(RKC, an Explicit Solver for Parabolic PDEs)and J.M. Hyman(Los Alamos)(Minimizing Numerical Er-rors Introduced by Operator Splitting Methods) Colloquium‘Flow and Transport in Porous Me-dia’,CWI,September24.Speakers:A.de Wit (Brussels)and R.J.Schotting(CWI).Organizers: R.J.Schotting and C.J.van Duijn.Workshop‘Interfaces and Parabolic Regularisa-tion’,Lorentz Center(RUL),November5–7.In-ternational workshop with25speakers anizers:J.Hulshof and C.J.van Duijn.MAS Colloquium,CWI,anizer: C.J.van Duijn.Speakers:C.N.Dawson(UT at Austin)(Dynamic Adaptive Methods for Chemi-cally Reactive Transport in Porous Media),P.Wes-seling(TUD)(Numerical Solution of Hyperbolic Systems with Nonconvex Equation of State)and W.A.Mulder(Shell Rijswijk)(Finite Differences and Finite Elements for Seismic Simulation). TASC Symposium9,CWI,ani-zers:J.G.Verwer and J.Kok.Speakers:A.Peter-sen(IMAU)(More Efficient Advection Schemes for the Global Atmospheric Tracer Model),H.Elbern (EURAD)(A Parallel Implementation of a4D-variational Chemistry Data Similation Scheme), E.J.Spee(Rosenbrock Methods for Atmospheric Dispersion Problems)and M.Krol(IMAU)(The TM3Model:Numerical Aspects of Atmospheric Chemistry Aplications).2nd Annual Meeting MMARIE Concerted Action, Barcelona,January15–17:B.P.Sommeijer(Do-main Decomposition for an Implicit Shallow-water Transport Solver).Meeting of the DFG Panel for the Sonderforsbe-reich1578,M¨u nchen,January16–17:Participa-tion by C.J.van Duijn.Meeting of the Scientific Council of the Weier-strass Institut f¨u r Angewandte Analysis und Sto-chastik,Berlin,January24:C.J.Van Duijn partici-pates and is elected vice-chairman of this council. Guest Lectures at the University of Amsterdam, within the framework of the course‘Parallel Scientific Computing and Simulation’,February21 and26:B.P.Sommeijer(Parallel ODE solvers). Harburger Sommerschulen,TU Hamburg-Harburg, February24–28:J.G.Verwer invited speaker (three lectures on the Method of Lines). Universidad Complutense de Madrid,Madrid, March19–23:C.J.van Duijn visits J.I.Diaz.32e Nederlands Mathematisch Congres,Wage-ningen,April3–4:W.Hundsdorfer(Stability of the Douglas Splitting Method),E.J.Spee(Ad-vectieschema’s op een Bol voor Atmosferische Transport-modellen).Istituto per le Applicazioni del Calcolo‘Mauro Pi-cone’,Rome,April7–11:C.J.van Duijn visits M. Bertsch.1st ERCIM Environmental Modelling Group Workshop on Air Pollution Modelling,GMD FIRST,Berlin,April7–8:J.G.Blom(An Evalua-tion of the Cray T3D Programming Paradigms in Atmospheric Chemistry/transport Problems),J.G. Verwer(A Numerical Study for Atmospheric Che-mistry/transport Problems).Both invited. Measurements and Modelling in Environmen-tal Pollution,Madrid,April22–24:M.van Loon (Data Assimilation for Atmospheric Chemistry Models).22nd General Assembly of the European Geo-physical Society,Vienna,April21–25:B.P.Som-meijer(A Fully Implicit3D Transport-chemistry Solver Combined with Domain Decomposition). NWO Symposium Massaal Parallel Rekenen, Veldhoven,May22:J.G.Verwer invited speaker (High Performance Computing and Environmental Pollutions).。