1,720,981 research outputs found
Special issue: The 10th International Symposium on Electric and Magnetic Fields (EMF 2016)
Full text linkpeer reviewe
Numerical dosimetry of currents induced in the human body by ELF magnetic fields
No full textPurpose: The classical φ-a formulations for numerical dosimetry of currents induced by extremely low frequency magnetic fields requires that the source field is provided through a vector potential. The purpose of this paper is to present a new formulation t-b which directly takes the flux density as source term. Design/methodology/approach: This formulation is implemented through finite element and validated by comparison with analytical solutions. The results obtained by both formulations are compared in the case of an anatomical computational phantom exposed to a vertical uniform field. Findings: A good agreement between the t-b formulation and both numerical and analytical computations was found. Originality/value: This new formulation seems to be more accurate than the φ-a formulation, and is more suited for situations where the magnetic field is known from experimental measurements, as there is no need for a magnetic vector potential. © Emerald Group Publishing Limited
Failure time and critical behaviour of fracture precursors in heterogeneous materials
No full textThe acoustic emission of fracture precursors, and the failure time of samples of heterogeneous materials (wood, fiberglass) are studied as a function of the load features and geometry. It is shown that in these materials the failure time is predicted with a good accuracy by a model of microcrack nucleation proposed by Pomeau. We find that the time interval δt between events (precursors) and the energy ε are power law distributed and that the exponents of these power laws depend on the load history and on the material. In contrast, the cumulated acoustic energy E presents a critical divergency near the breaking time τ which is E ∼ (τ-t/τ)-γ. The positive exponent γ is independent, within error bars, on all the experimental parameters
Effect of tissue parameters on skin heating due to millimeter em waves
No full textThis paper investigates the influence of electrical and thermal human tissue parameters on the heating of a body illuminated by a millimeter plane electromagnetic wave. A stochastic approach is considered with a three-layer model of the body: it is found that the parameters of skin play a major role
Domain decomposition for computing extremely low frequency induced current in the human body
No full textComputation of electromagnetic fields in high resolution computational phantoms requires solving large linear systems. We present the application of Schwarz preconditioners with Krylov subspace methods for computing Extremely Low Frequency (ELF) induced fields in a phantom. © 2010 IEEE
Effect of tissue parameters on skin heating due to millimeter EM waves
Full text linkThis paper investigates the influence of electrical and thermal human tissue parameters on the heating of a body illuminated by
a millimeter plane electromagnetic wave. A stochastic approach is considered with a three-layer model of the body: it is found that
the parameters of skin play a major role
Electromagnetic fields and human body: A new challenge for the electromagnetic field computation
No full textThe electromagnetic fields have a great influence on the behaviour of all the living systems. The as low as reasonably achievable (ALARA) principle imposes, in case of long exposures to low (i.e. power systems) or high frequency (i.e. microwave systems or cell phones) fields, some limitations to the radiated field by the industrial equipment. On the other hand, some benefits can be taken from the effects of the electromagnetic fields on the living being: the hyperthermal technique is well known for the treatment of the cancer. Either we want to be protected from the fields, or we want to take benefit of the positive effects of these fields, all the effects thermal as well as genetic have to be well known. Like in any industrial application, the electromagnetic field computation allows a better knowledge of the phenomena, and an optimised design. Hence, there is a very important challenge for the techniques of computation of electromagnetic fields. The major difficulties that appear are: (1) related to the material properties - the "material" (the human body) has very unusual properties (magnetic permeability, electric permittivity, electric conductivity), these properties are not well known and depend on the activity of the person, and this material is an active material at the cell scale; (2) related to the coupling phenomena - the problem is actually a coupled problem: the thermal effects is one of the major effects and it is affected by the blood circulation; (3) related to the geometry - the geometry is complex and one has to take into account the environment. The problems that we have to face with are - the identification of the properties of the "material", the coupled problem solution and the representation of the simulated phenomena
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
