scholarly journals Reconstruction of a Segment of the UNESCO World Heritage Hadrian’s Villa Tunnel Network by Integrated GPR, Magnetic-Paleomagnetic, and Electric Resistivity Prospections

2019 ◽  
Author(s):  
Annalisa Ghezzi ◽  
Antonio Schettino ◽  
Pietro Paolo Pierantoni ◽  
Lawrence Conyers ◽  
Luca Tassi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Structural Model ◽  
World Heritage ◽  
High Amplitude ◽  
Electric Resistivity ◽  
Computer Assisted ◽  
Unesco World Heritage ◽  
Field Modelling ◽  
Underground System ◽  
The Magnetic Field

The UNESCO World Heritage Hadrian’s Villa lies over the Colli Albani volcanic district near Rome. Magnetic, paleomagnetic, radar, and electric resistivity surveys were performed in the Plutonium–Inferi sector to detect buried buildings and outline a segment of the underground system of tunnels that link different zones of the villa. In particular, a paleomagnetic analysis of the bedrock unit allowed to accomplish an accurate geomagnetic field modelling and characterize the archaeological sources of the magnetic field anomalies. We used a computer-assisted forward modelling procedure to generate a structural model of the sources of the observed anomalies. The intrinsic ambiguity of the magnetic field modelling was reduced with the support of ground penetrating radar amplitude slices and an analysis of radar and electric resistivity profiles. The bedrock lithology in this area is an ignimbrite tuff characterized by abundant iron oxides. The high-amplitude magnetic anomalies observed in the Plutonium–Inferi area are due to strong bedrock remnant magnetization and susceptibility contrasts between topsoil infill of cavities and the surrounding tuff. The resulting magnetization model of the Plutonium–Inferi complex shows that the observed anomalies are mostly due to the presence of tunnels, skylights and a system of ditches excavated in the tuff.

scholarly journals Reconstruction of a Segment of the UNESCO World Heritage Hadrian’s Villa Tunnel Network by Integrated GPR, Magnetic–Paleomagnetic, and Electric Resistivity Prospections

2019 ◽  
Vol 11 (15) ◽  
pp. 1739
Author(s):  
Annalisa Ghezzi ◽  
Antonio Schettino ◽  
Pietro Paolo Pierantoni ◽  
Lawrence Conyers ◽  
Luca Tassi ◽  
...  
Keyword(s):  
Archaeological Site ◽  
Magnetic Anomalies ◽  
High Amplitude ◽  
Electric Resistivity ◽  
Computer Assisted ◽  
Aerial Photogrammetry ◽  
Comprehensive Picture ◽  
Hadrian’S Villa ◽  
Hadrian's Villa ◽  
Underground System

Hadrian’s Villa is an ancient Roman archaeological site built over an ignimbritic tuff and characterized by abundant iron oxides, strong remnant magnetization, and elevated magnetic susceptibility. These properties account for the high-amplitude magnetic anomalies observed in this site and were used as a primary tool to detect deep archaeological features consisting of air-filled and soil-filled cavities of the tuff. An integrated magnetic, paleomagnetic, radar, and electric resistivity survey was performed in the Plutonium-Inferi sector of Hadrian’s Villa to outline a segment of the underground system of tunnels that link different zones of the villa. A preliminary paleomagnetic analysis of the bedrock unit and a high-resolution topographic survey by aerial photogrammetry allowed us to perform a computer-assisted modelling of the observed magnetic anomalies, with respect to the archaeological sources. The intrinsic ambiguity of this procedure was reduced through the analysis of ground penetrating radar and electric resistivity profiles, while a comprehensive picture of the buried archaeological features was built by integration of the magnetization model with radar amplitude maps. The final subsurface model of the Plutonium-Inferi complex shows that the observed anomalies are mostly due to the presence of tunnels, skylights, and a system of ditches excavated in the tuff.

3D Magnetic Field Modelling and Force Computation of a Permanent Magnet Linear Actuator

2009 ◽  
Vol 152-153 ◽  
pp. 411-414
Author(s):  
Ivan Yatchev ◽  
Krastyo Hinov ◽  
Vultchan Gueorgiev
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Three Dimensional ◽  
Force Characteristic ◽  
Linear Actuator ◽  
Static Force ◽  
Field Modelling ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
The Magnetic Field

Three-dimensional finite element method has been used for modelling of the magnetic field and computation of the electromagnetic force of recently developed permanent magnet linear actuator. The actuator is subject to specific requirements – having four stable positions without supply and maintaining minimum static force during the whole working stroke. The actuator consists of several cores with coils placed on a common yoke and a moving permanent magnet. It is intended for needle driving in a knitting machine. Influence of different factors on the static force characteristic is estimated.

Natural convection in horizontal pipe flow with a strong transverse magnetic field

2013 ◽  
Vol 720 ◽  
pp. 486-516 ◽  
Author(s):  
Oleg Zikanov ◽  
Yaroslav I. Listratov ◽  
Valentin G. Sviridov
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Transverse Magnetic Field ◽  
Metal Flow ◽  
Low Frequency ◽  
High Amplitude ◽  
Transverse Magnetic ◽  
Mean Flow ◽  
Horizontal Pipe ◽  
The Magnetic Field

AbstractLinear stability analysis and direct numerical simulations are conducted to analyse mixed convection in a liquid metal flow in a horizontal pipe with imposed transverse magnetic field. The pipe walls are electrically insulated and subject to constant flux heating in the lower half. The results reveal the nature of anomalous temperature fluctuations detected in earlier experiments. It is found that, at the magnetic field strength far exceeding the laminarization threshold, the natural convection develops in the form of coherent quasi-two-dimensional rolls aligned with the magnetic field. Transport of the rolls by the mean flow causes high-amplitude, low-frequency fluctuations of temperature.

scholarly journals Possible Hydromagnetic Simulation of Cosmical Phenomena in the Laboratory

1958 ◽  
Vol 8 ◽  
pp. 1090-1094
Author(s):  
Winston H. Bostick
Keyword(s):  
Magnetic Field ◽  
Magnetic Reynolds Number ◽  
Electric Resistivity ◽  
Conducting Medium ◽  
Ionized Gas ◽  
Plasma Gun ◽  
Electrically Conducting ◽  
Magnetic Forces ◽  
Gas Plasma ◽  
The Magnetic Field

A technique has been developed whereby ionized gas (plasma) can be projected, by magnetic forces, at speeds of 3X107 cm/sec through a vacuum region free from a magnetic field. The plasma has also been projected across magnetic fields in vacuum at speeds of 107 cm/sec. It is further possible to have present in the magnetic field a background electrically conducting medium in the form of a low-pressure (about one micron) ionized gas. This gas is photoionized by the ultraviolet light from the plasma gun. With the background conducting medium we can calculate, following Spitzer, the electric resistivity η transverse to a strong magnetic field to be η = 1.29X1013(Z lnΛ)T−3/2 emu = 106 emu for T=105 °K (electron temperature), Z=1, lnΛ = 2.3. The magnetic Reynolds number Rm for L =10 cm and V = 107 cm/sec is thus Rm=4πLV/η = 103. Consequently, there is no doubt that with this technique we are producing magnetohydrodynamic phenomena in the laboratory.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

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