Dispersion Forces II

Dispersion Forces II

In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of different aspects and scenarios. Macroscopic quantum electrodynamics is applied within the context of dispersion forces. In contrast to the normal-mode quantum electrodynamics traditionally used to study dispersion forces, the new approach allows to consider realistic material properties including absorption and is flexible enough to be applied to a broad range of geometries. Thus general properties of dispersion forces like their non-additivity and the relation between microscopic and macroscopic dispersion forces are discussed. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. In particular, nontrivial magnetic properties of the bodies, bodies of irregular shapes, the role of material absorption, and dynamical forces for excited atoms are discussed. This volume 2 deals especially with quantum electrodynamics, dispersion forces, Casimir forces, asymptotic power laws, quantum friction and universal scaling laws. The book gives both the specialist and those new to the field a thorough overview over recent results in the context of dispersion forces. It provides a toolbox for studying dispersion forces in various contexts.

Dispersion Forces II

Dynamics of Machinery

Dynamics of Machinery

Dynamic loads and undesired oscillations increase with higher speed of machines. At the same time, industrial safety standards require better vibration reduction. This book covers model generation, parameter identification, balancing of mechanisms, torsional and bending vibrations, vibration isolation, and the dynamic behavior of drives and machine frames as complex systems.Typical dynamic effects, such as the gyroscopic effect, damping and absorption, shocks, resonances of higher order, nonlinear and self-excited vibrations are explained using practical examples. These include manipulators, flywheels, gears, mechanisms, motors, rotors, hammers, block foundations, presses, high speed spindles, cranes, and belts. Various design features, which influence the dynamic behavior, are described.The book includes 60 exercises with detailed solutions. The substantial benefit of this ‘Dynamics of Machinery’ lies in the combination of theory and practical applications and the numerous descriptive examples based on real-world data. The book addresses graduate students as well as engineers.

Dynamics of Machinery

Liquid Crystalline Semiconductors

Liquid Crystalline Semiconductors

Liquid Crystals [LCs] are synthetic functional materials par excellence and are to be found in many types of LCDs; LCs self-assemble into ordered, but fluid, supramolecular structures and domains; they can be oriented in large homogeneous monodomains by electric and magnetic fields, Langmuir Blodgett techniques and also by self-orientation on suitable alignment layers; they are also anisotropic with preferred axes of light absorption, emission and charge transport with excellent semiconducting properties; they are soluble in organic solvents and can be deposited as uniform thin layers on device substrates, including plastic, by low-cost deposition processes, such as spin coating and doctor blade techniques; reactive mesogens [polymerisable LC monomers] can be photopatterned and fixed in position and orientation as insoluble polymer networks. LCs are increasingly being used as active components in electronic and photonic organic devices, such as Organic Light-Emitting Diodes [OLEDs], Organic Field Effect Transistors [OFETs], Thin Film Transistors [TFTs] and photovoltaic cells [PVs]. Such devices on plastic substrates represent a major component of the plastic electronics revolution. The self-assembling properties and supramolecular structures of liquid crystals can be made use of in order to improve the performance of such devices. The relationships between chemical structure, liquid crystalline behaviour and other physical properties, such as charge-transport, photoluminescence and electroluminescence are discussed and explained. For example, high carrier-mobility, polarised emission and enhanced output-coupling are identified as the key advantages of nematic and smectic liquid crystals for electroluminescence. The advantageous use of anisotropic polymer networks formed by the polymerisation of reactive mesogens [RMs] in devices with multilayer capability and photopatternability is described. The anisotropic transport and high carrier mobilities of columnar liquid crystals make them promising candidates for photovoltaics and transistors. The issues in the design and processing of liquid crystalline semiconductors for such devcies with improved performance are described. The photonic properties of chiral liquid crystals and their use as mirror-less lasers are also discussed.

Liquid Crystalline Semiconductors