Author: Publisher: Ed. Techniques Ingénieur
ISBN:
Category :
Languages : fr
Pages : 11
Book Description
Spectrometrie Photoacoustique: Application a I'analyse de Gaz
Author: Publisher: Ed. Techniques Ingénieur
ISBN:
Category :
Languages : fr
Pages : 11
Book Description
Spectrométrie laser photoacoustique
Author: Chehem Mohamed ibrahimPublisher:
ISBN:
Category :
Languages : fr
Pages : 0
Book Description
Dans l'infrarouge, la spectrométrie laser est à la base de nombreuses techniques extrêmement efficaces pour la détection de traces de gaz. Parmi ces techniques, la spectrométrie photoacoustique (PA) présente l'originalité de ne pas être basée sur une mesure de l'atténuation du faisceau laser à la traversée du gaz, mais sur la mesure indirecte de l'énergie absorbée par cet échantillon au moyen de l'onde acoustique générée par l'échauffement du gaz. Cette technique présente de nombreux avantages en terme de robustesse et de dynamique de mesure. Un modèle basé sur la FEM a permis de compléter les études précédentes sur la modélisation de cuves PA suivant leur taille et d'améliorer la prédiction des limites de détection attendues.Cependant, dans des conditions particulières (nature du mélange de gaz ou présence d'impuretés), le signal PA peut parfois présenter une variation non-linéaire en fonction de la concentration du gaz visé, limitant l'intérêt pour la détection de gaz. L'étude des problématiques de la détection de molécules gazeuses par spectrométrie laser PA lorsque le signal PA n'est pas proportionnel à la concentration de gaz a donc été réalisée. Dans un premier temps, l'étude de la relaxation de molécules de dioxyde de carbone a été réalisée démontrant un très bon accord entre les valeurs expérimentales issues de la littérature et les simulations réalisées. Le modèle a ensuite été utilisé pour l'étude de la relaxation du méthane dans le proche et dans le moyen infrarouge. Là encore, les modélisations montrent un bon accord entre les simulations réalisées et les mesures expérimentales. Ces résultats permettront d'anticiper les conditions pour lesquelles une non-linéarité du signal PA pourra se produire.
Application of Particle and Laser Beams in Materials Technology
Author: P. MisaelidesPublisher: Springer Science & Business Media
ISBN: 9780792333241
Category : Science
Languages : en
Pages : 702
Book Description
The development of advanced materials with preselected properties is one of the main goals of materials research. Of especial interest are electronics, high-temperature and superhard materials for various applications, as well as alloys with improved wear, corrosion and mechanical resistance properties. The technical challenge connected with the production of these materials is not only associated with the development of new specialised preparation techniques but also with quality control. The energetic charged particle, electron and photon beams offer the possibility of modifying the properties of the near-surface regions of materials without seriously affecting their bulk, and provide unique analytical tools for testing their quality. Application of Particle and Laser Beams in Materials Technology provides an overview of this rapidly expanding field. Fundamental aspects concerning the interactions and collisions on atomic, nuclear and solid state scale are presented in a didactic way, along with the application of a variety of techniques for the solution of problems ranging from the development of electronics materials to corrosion research and from archaeometry to environmental protection. The book is divided into six thematic units: Fundamentals, Surface Analysis Techniques, Laser Beams in Materials Technology, Accelerator-Based Techniques in Materials Technology, Materials Modification and Synchrotron Radiation.
Photosynthetic Adaptation
Author: William K SmithPublisher: Springer Science & Business Media
ISBN: 0387272674
Category : Science
Languages : en
Pages : 317
Book Description
This is a thorough study of photosynthetic mechanisms from cells to leaves, crown, and canopy. The authors question whether photosynthetic adaptations take place primarily at the metabolic and biochemical level or through changes in structure and form, or both. The text goes on to analyze the relative importance of genes that control metabolic and light reactions, and the structure, arrangement, and orientation of photosynthesis.
Deficit Irrigation Practices
Author: Food and Agriculture Organization of the United NationsPublisher: Food & Agriculture Org.
ISBN: 9789251047682
Category : Technology & Engineering
Languages : en
Pages : 116
Book Description
In the context of improving water productivity, there is a growing interest in deficit irrigation, an irrigation practice whereby water supply is reduced below maximum levels and mild stress is allowed with minimal effects on yield. Under conditions of scarce water supply and drought, deficit irrigation can lead to greater economic gains than maximizing yields per unit of water for a given crop; farmers are more inclined to use water more efficiently, and more water-efficient cash crop selection helps optimize returns. However, this approach requires precise knowledge of crop response to water as drought tolerance varies considerably by species, cultivar and stage of growth. The studies present the latest research concepts and involve various practices for deficit irrigation. Both annual and perennial crops were exposed to different levels of water stress, either during a particular growth phase, throughout the whole growing season or in a combination of growth stages. The overall finding, based on the synthesis of the different contributions, is that deficit or regulated-deficit irrigation can be beneficial where appropriately applied. Substantial savings of water can be achieved with little impact on the quality and quantity of the harvested yield. However, to be successful, an intimate knowledge of crop behavior is required, as crop response to water stress varies considerably.
Sensors, Update 2
Author: Henry BaltesPublisher: Wiley-VCH
ISBN:
Category : Science
Languages : en
Pages : 256
Book Description
Offers a review of current highlights in the field of sensors, and should be particularly useful for researchers planning to invest in new instrumentation. There is a section on sensor markets, providing an overview of suppliers and market trends for a particular sector.
Hydraulics in Civil and Environmental Engineering
Author: Andrew ChadwickPublisher: CRC Press
ISBN: 1000395553
Category : Technology & Engineering
Languages : en
Pages : 652
Book Description
This classic text, now in its sixth edition, combines a thorough coverage of the basic principles of civil engineering hydraulics with a wide-ranging treatment of practical, real-world applications. It now includes a powerful online resource with worked solutions for chapter problems and solution spreadsheets for more complex problems that may be used as templates for similar issues. Hydraulics in Civil and Environmental Engineering is structured into two parts to deal with principles and more advanced topics. The first part focuses on fundamentals, such as hydrostatics, hydrodynamics, pipe and open channel flow, wave theory, physical modelling, hydrology and sediment transport. The second part illustrates engineering applications of these principles to pipeline system design, hydraulic structures, river and coastal engineering, including up-to-date environmental implications, as well as a chapter on computational modelling, illustrating the application of computational simulation techniques to modern design, in a variety of contexts. New material and additional problems for solution have been added to the chapters on hydrostatics, pipe flow and dimensional analysis. The hydrology chapter has been revised to reflect updated UK flood estimation methods, data and software. The recommendations regarding the assessment of uncertainty, climate change predictions, impacts and adaptation measures have been updated, as has the guidance on the application of computational simulation techniques to river flood modelling. Andrew Chadwick is an honorary professor of coastal engineering and the former associate director of the Marine Institute at the University of Plymouth, UK. John Morfett was the head of hydraulics research and taught at the University of Brighton, UK. Martin Borthwick is a consultant hydrologist, formerly a flood hydrology advisor at the UK’s Environment Agency, and previously an associate professor at the University of Plymouth, UK.
On the Origins of Chloroplasts
Author: National Institute of Allergy and Infectious Diseases (U.S.)Publisher: North Holland
ISBN:
Category : Science
Languages : en
Pages : 372
Book Description
Analytical Voltammetry
Author: M.R. SmythPublisher: Elsevier Science
ISBN: 9780444889386
Category : Science
Languages : en
Pages : 578
Book Description
The aim of this volume is to review the state-of-the-art in analytical voltammetry with regard to theory and instrumentation, and show how these relate to the analysis of inorganic, organometallic, organic and biological molecules. Modern voltammetric techniques have practical applications in biological, pharmaceutical and environmental chemistry. The growing importance of voltammetry in the development of modified electrodes and biological electrodes and chemical and biological sensors is also highlighted.
Author: