Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Capacity propagation

Phonons are nomial modes of vibration of a low-temperatnre solid, where the atomic motions around the equilibrium lattice can be approximated by hannonic vibrations. The coupled atomic vibrations can be diagonalized into uncoupled nonnal modes (phonons) if a hannonic approximation is made. In the simplest analysis of the contribution of phonons to the average internal energy and heat capacity one makes two assumptions (i) the frequency of an elastic wave is independent of the strain amplitude and (ii) the velocities of all elastic waves are equal and independent of the frequency, direction of propagation and the direction of polarization. These two assumptions are used below for all the modes and leads to the famous Debye model. [Pg.412]

Impact and Erosion. Impact involves the rapid appHcation of a substantial load to a relatively small area. Most of the kinetic energy from the impacting object is transformed into strain energy for crack propagation. Impact can produce immediate failure if there is complete penetration of the impacted body or if the impact induces a macrostress in the piece, causing it to deflect and then crack catastrophically. Failure can also occur if erosion reduces the cross section and load-bearing capacity of the component, causes a loss of dimensional tolerance, or causes the loss of a protective coating. Detailed information on impact and erosion is available (49). [Pg.325]

Since, as we have continually been reminded throughout this book, the capacity for some kind of signal propagation is critical for being able to perform arbitrary computational processes, it should come as no surprise that there is a finite intersection between both context-sensitive and unrestricted Chomsky languages - the latter, of which, we recall require the class of universal computers as their accept-... [Pg.579]

Excitability refers to the capacity of nerves and other tissues (e.g. cardiac), as well as individual cells, to generate and sometimes propagate action potentials, signals that serve to control intracellular processes, such as muscle contraction or hormone secretion, and to allow for long- and short-distance communication within the organism. Examples of excitable cells and tissues include neurons, muscle and endocrine tissues. Examples of nonexcitable cells and tissues include blood cells, most epithelial and connective tissues. [Pg.487]

The polarizability expresses the capacity of a system to be deformed under the action of electric field it is the first-order response. The hyperpolarizabilities govern the non linear processes which appear with the strong fields. These properties of materials perturb the propagation of the light crossing them thus some new phenomenons (like second harmonic and sum frequency generation) appear, which present a growing interest in instrumentation with the lasers development. The necessity of prediction of these observables requires our attention. [Pg.261]

The major lipid-soluble antioxidant primarily associated with lipid membranes is a-tocopherol (vitamin E). Circulating a-tocopherol is carried by chylomicrons, LDL and HDL and also has extracellular antioxidant capacities. As a chain-breaking antioxidant, it short circuits the propagation phase of lipid peroxidation because the peroxyl radical will react with a-tocopherol more rapidly than a polyunsaturated ffitty acid (Burton and Traber, 1990). The resulting a-tocopheryl radical reacts with a second peroxyl radical to form an inactive, nonradical complex. In vitro, ascorbate regenerates the tocopheryl radical into its native non-radical form (Burton and Traber, 1990). [Pg.101]

I offer a different and complementary perspective on units which accommodates developmental processes explicitly and which articulates the intimate relationship between units of hereditary transmission and developmental expression. I argue that a process perspective on the temporal dimension of the transition problem, focusing on the propagation of developmental capacities, is a helpful addition to the spatial and functional perspectives. Reproduction is the process that, in general, forms the basis for evolution at a level and also for evolutionary transition to new levels. Processes of inheritance and replication can be understood as special cases of reproduction. In order to formulate a view of how processes of development and hereditary propagation are intertwined in reproduction, let us consider development further. [Pg.214]

I suggest that we take the acquisition of the total set of species-typical traits (however that is to be measured empirically) to be a maximum specification of the process of development. Anything more exhaustive than species-typical might entail that new species could not evolve. As a minimum bound, I suggest the following evolutionary specification - development is the acquisition of the capacity to reproduce. It will become clear in a moment why I bracket the process of development in this way. First, though, let us consider the sorts of questions about development at multiple levels of evolutionary transition that must be addressed if we are to understand units of evolutionary transition in terms of the propagation of developmental capacities. [Pg.215]

Concrete is an inherently brittle material with low tensile strength and strain capacities. Its brittle characteristics lead to easy nucleation and propagation of cracks, thus restricting its range of applications. To address this deficiency, fibers of different materials such as asbestos, glass, metal, and synthetics " are used as additives, with the following results"" ... [Pg.255]

Metal transport and deposition capacities of mineral systems are closely linked to propagation of redox and related physicochemical gradients (pH, aH2, aHCI, aH2S, aS02, aC02, aCH4, aH20, etc) within mineral systems. For metals transported in solution, the rate of mineralization is a product of 3 factors (see Fig. 2) ... [Pg.223]


See other pages where Capacity propagation is mentioned: [Pg.95]    [Pg.153]    [Pg.95]    [Pg.153]    [Pg.203]    [Pg.23]    [Pg.384]    [Pg.196]    [Pg.419]    [Pg.205]    [Pg.31]    [Pg.77]    [Pg.246]    [Pg.53]    [Pg.26]    [Pg.30]    [Pg.101]    [Pg.132]    [Pg.352]    [Pg.114]    [Pg.15]    [Pg.219]    [Pg.11]    [Pg.271]    [Pg.491]    [Pg.349]    [Pg.26]    [Pg.402]    [Pg.560]    [Pg.279]    [Pg.180]    [Pg.180]    [Pg.301]    [Pg.173]    [Pg.218]    [Pg.255]    [Pg.98]    [Pg.86]    [Pg.19]    [Pg.184]    [Pg.402]   
See also in sourсe #XX -- [ Pg.81 , Pg.177 ]




SEARCH



© 2024 chempedia.info