We present new, full geomagnetic field vector results from three Neolithic ovens discovered at th... more We present new, full geomagnetic field vector results from three Neolithic ovens discovered at the archaeological site of Portonovo (Marche, Italy). The discovered structures are a rare example of very well preserved underground ovens from the Early Neolithic period. Standard thermal demagnetization procedures were used to isolate the direction of the Characteristic Remanent Magnetization acquired by the baked clay during the ovens' last firing. The corresponding archaeointensities were determined by the multi-specimen procedure (MSP-DSC) and show a clear intensity low during the Neolithic period. Both directional and intensity results are of high quality, offering the first contribution of full geomagnetic field vector data for this period in Italy. The new data are compared with other contemporaneous data from Europe and with global geomagnetic field models. Independent archaeomagnetic dating of the three ovens was also performed by means of the SCHA.DIF.14k model. The obtained results are in excellent agreement with available radiocarbon dates and confirm that all ovens belong to the Neolithic. These new data importantly enrich our knowledge of the geomagnetic field during the Neolithic period that is poorly documented by data, not only in Italy but also in the whole of Europe and show that archaeomagnetic dating can provide precise results even for prehistoric periods.
Modern Science, an essay written by Lev Nikolàevič Tolstoy in 1898 is here reproduced in its comp... more Modern Science, an essay written by Lev Nikolàevič Tolstoy in 1898 is here reproduced in its complete version, as a historical document containing philosophical reflections on the practical functions and the cultural and educational role science has, or should have, in contemporary societies. The text was cited by Aldous Huxley in the foreword to Science, Liberty and Peace, a booklet written in 1946 in the aftermath of the second world war, with the threat of nuclear doomsday on the horizon. Are science and technology really at the service of universal needs, as it is continuously claimed – Tolstoy asks, and Huxley echoes – or are their services rather directed to preserving the power of the elites or dominant classes against the multitude of the oppressed? Keywords: Science and Peace, Science and Art, Lev Tolstoy, Aldous Huxley
Per quanto riguarda il sistema tampone pH-metrico dell'acqua di mare, va notato che esso è as... more Per quanto riguarda il sistema tampone pH-metrico dell'acqua di mare, va notato che esso è assai complesso a causa degli equilibri eterogenei del sistema HCO3 - /CO3 2- /CO2 (per la protonazione del carbonato si ha: logKH1 = 9.61, logK H 2 = 6.00 a I = 0.5 mol L -1 e T = 25 °C (5)). A questo sistema si aggiunge lo ione diidrogenoborato (H3BO2 - ), la cui costante di protonazione vale logKH = 8.87 a 25°C e I = 0.5 mol L-1 (5). Nelle acque marine di superficie
György Darvas has been a dedicated organizer of symmetry meetings and editor of the periodical Sy... more György Darvas has been a dedicated organizer of symmetry meetings and editor of the periodical Symmetry. His enthusiasm has now spilled over into a 500-page book whose material is divided into five parts: Introductory chapters; Interdisciplinary Applications; ...
IEEE Transactions on Aerospace and Electronic Systems
A magnetic damping system for nanospacecraft attitude stabilization is proposed, based on the use... more A magnetic damping system for nanospacecraft attitude stabilization is proposed, based on the use of thin strips of amorphous Fe-B-Si soft magnetic ribbons. The size, number, and location of the strips is optimized, and a predictive formulation is provided. The main result of ground tests, comparing the performance of several soft magnetic materials, is that suitably heat-treated amorphous ribbons provide the best loss performance in the whole range of magnetic fields expected in orbit.
ABSTRACT We present a detailed rock-magnetic and archaeomagnetic study of two brick kilns, named ... more ABSTRACT We present a detailed rock-magnetic and archaeomagnetic study of two brick kilns, named OSA and OSB, discovered at the location of Osterietta, in northern Italy. The magnetic properties of representative samples have been investigated to identify the nature of the magnetic carriers, their domain state and thermal stability, and investigate their suitability for archaeomagnetic determinations. Thermally stable, mainly pseudosingle domain (PSD) magnetite is identified as the main magnetic carrier. The full geomagnetic field vector has been determined for the two kilns, including directional and intensity analysis. Archaeointensities have been recovered with both the classical Thellier and the multi-specimen protocols. The multi-specimen procedure was performed with a very fast-heating oven developed at Montpellier, France. A Matlab® code for anisotropy correction during the Thellier experiment is provided. The archaeointensity results obtained from both techniques for the OSA kiln are of high quality and in good mutual agreement. For the OSB kiln, Thellier results are characterized by large standard deviation and the multi-specimen (MSP) technique was not successful. The obtained full geomagnetic field vector (declination, inclination and intensity) has been used for the archaeomagnetic dating of the two structures suggesting that the OSA kiln was for the last time used between 1761?1841 A.D. and the OSB kiln between 1752?1831 A.D., at 95% probability. This study shows that intensity determinations do not restrict the dating results when referring to the last few centuries, as this period is characterized by very small intensity variations.
The potential of magnetic grain-size variations as an obsidian source characteristic is investiga... more The potential of magnetic grain-size variations as an obsidian source characteristic is investigated using geological and archaeological obsidians from five islands of the Mediterranean Sea: Lipari, Sardinia, Palmarola, Pantelleria, Melos. Four parameters are used: magnetic (χ) and anhysteretic (χa) susceptibilities, saturation isothermal remanent magnetizations at room (SIRM293) and liquid nitrogen (SIRM77) temperature. The ratio ST = SIRM77/SIRM293, which depends on the superparamagnetic grains relative abundance, varies little in each individual site, with the exception of Lipari which is characterized by large variations and the highest content of superparamagnetic grains. The χa vs. χ plot (King et al., 1982) shows some within-site dispersion of the samples; but the ratio Qa = χa/χ, which is strongly influenced by the single domain grains content, is characteristic for each site. The combined use of the King and Qa vs. ST plots discriminates the samples from most of the sites a...
Significant results are reported concerning the magnetic behavior of sintered soft ferrites and v... more Significant results are reported concerning the magnetic behavior of sintered soft ferrites and very thin Co-based amorphous ribbons up to 1 GHz. Conveniently field-annealed amorphous tapes can exhibit, in spite of their metallic character, superior combination of magnetic loss and permeability properties at all frequencies. Such properties are phenomenologically assessed through a physical approach based on the statistical theory of losses and the generalization of the related concept of loss separation, which takes into account different dissipation mechanisms and discriminates between domain wall and rotational processes. The latter, in particular, are described in ferrites in association with spin precession and damping and are given a formulation based on the Landau-Lifshitz-Gilbert equation and the assumption of distributed effective anisotropy fields.
Results on the production, structure and magnetic properties of (Fe100−xCox)73.5Cu1Nb3Si13.5B9 (x... more Results on the production, structure and magnetic properties of (Fe100−xCox)73.5Cu1Nb3Si13.5B9 (x = 0, 5, 10, 20) wires obtained by the in rotating water quenching technique, both in the amorphous and nanocrystalline state are reported. The obtained results are compared with that obtained for the FINEMET alloy. The saturation magnetostriction decreases when increasing the Co content in the amorphous wires and
The discovery and large scale investigation of rapidly solidified alloys have brought to light, i... more The discovery and large scale investigation of rapidly solidified alloys have brought to light, in the last two decades, a new scenario in basic and applied magnetism. With a range of compositions and microstructural states unavailable to conventional materials, the rapidly quenched alloys have in fact demonstrated unprecedented versatile properties, provided unique opportunities in applications and stirred up the domain
The dependence of structural properties of Fe (Si) 6. 5 wt.% ribbons on annealing treatments has ... more The dependence of structural properties of Fe (Si) 6. 5 wt.% ribbons on annealing treatments has been investigated in the temperature range 700-1300 °C. Two different annealing methods, respectively characterized by slow( ...
The effect of different melt temperature and of surface roughness on the magnetic properties of t... more The effect of different melt temperature and of surface roughness on the magnetic properties of the amorphous phase in Fe,,Co,,B,, alloy prepared by Planar Flow Casting (PFC) has been investigated. The obtained ribbons have been qagnetically characterized analyzing hysteresis loops and coercivity in the as-cast condition, after relaxation induced by field-annealing treatment and after thinning by chemical etching. Differential Scanning Calorimeter (DSC) has been used to quantitatively characterize structural relaxation and crystallization of the amorphous phase. Optical and Scanning Electron Microscopy (SEM) have been used to evaluate surface roughness. The average size of the surface grooves on the wheel side was found to increase with melt temperature and thickness. Magnetic properties have been observed to be mainly influenced by the roughness on the wheel side of the ribbons and surface frozen-in stresses are considered to be the main source for the magnetic anisotropy. Cryitallization process doesn't vary significantly among the samples, while relaxation heat was found to increase with thickness reduction. Melt temperature was related to previous remarks as controlling viscosity and thus modifying the wetting grade of the melt onto the cooling substrate. 0 1997 Elsevier Science S.A.
Rapidly solidified Fe-6. 5 wt% Si ribbons are fully ductile in the as-quenched state. However, th... more Rapidly solidified Fe-6. 5 wt% Si ribbons are fully ductile in the as-quenched state. However, the annealing process, required for optimization of the magnetic properties, generally leads to final brittle materials. In this article, a ...
Journal of Magnetism and Magnetic Materials 160 (1996) 151 153 H journal of N magnetism H and mag... more Journal of Magnetism and Magnetic Materials 160 (1996) 151 153 H journal of N magnetism H and magnetic H materials ELSEVIER The magnetic properties of FeSi 6.5 wt alloys obtained by a SiC14based CVD process S. CrottierCombe a, S. Audisio a, j. Degauque b, JL ...
We present new, full geomagnetic field vector results from three Neolithic ovens discovered at th... more We present new, full geomagnetic field vector results from three Neolithic ovens discovered at the archaeological site of Portonovo (Marche, Italy). The discovered structures are a rare example of very well preserved underground ovens from the Early Neolithic period. Standard thermal demagnetization procedures were used to isolate the direction of the Characteristic Remanent Magnetization acquired by the baked clay during the ovens' last firing. The corresponding archaeointensities were determined by the multi-specimen procedure (MSP-DSC) and show a clear intensity low during the Neolithic period. Both directional and intensity results are of high quality, offering the first contribution of full geomagnetic field vector data for this period in Italy. The new data are compared with other contemporaneous data from Europe and with global geomagnetic field models. Independent archaeomagnetic dating of the three ovens was also performed by means of the SCHA.DIF.14k model. The obtained results are in excellent agreement with available radiocarbon dates and confirm that all ovens belong to the Neolithic. These new data importantly enrich our knowledge of the geomagnetic field during the Neolithic period that is poorly documented by data, not only in Italy but also in the whole of Europe and show that archaeomagnetic dating can provide precise results even for prehistoric periods.
Modern Science, an essay written by Lev Nikolàevič Tolstoy in 1898 is here reproduced in its comp... more Modern Science, an essay written by Lev Nikolàevič Tolstoy in 1898 is here reproduced in its complete version, as a historical document containing philosophical reflections on the practical functions and the cultural and educational role science has, or should have, in contemporary societies. The text was cited by Aldous Huxley in the foreword to Science, Liberty and Peace, a booklet written in 1946 in the aftermath of the second world war, with the threat of nuclear doomsday on the horizon. Are science and technology really at the service of universal needs, as it is continuously claimed – Tolstoy asks, and Huxley echoes – or are their services rather directed to preserving the power of the elites or dominant classes against the multitude of the oppressed? Keywords: Science and Peace, Science and Art, Lev Tolstoy, Aldous Huxley
Per quanto riguarda il sistema tampone pH-metrico dell'acqua di mare, va notato che esso è as... more Per quanto riguarda il sistema tampone pH-metrico dell'acqua di mare, va notato che esso è assai complesso a causa degli equilibri eterogenei del sistema HCO3 - /CO3 2- /CO2 (per la protonazione del carbonato si ha: logKH1 = 9.61, logK H 2 = 6.00 a I = 0.5 mol L -1 e T = 25 °C (5)). A questo sistema si aggiunge lo ione diidrogenoborato (H3BO2 - ), la cui costante di protonazione vale logKH = 8.87 a 25°C e I = 0.5 mol L-1 (5). Nelle acque marine di superficie
György Darvas has been a dedicated organizer of symmetry meetings and editor of the periodical Sy... more György Darvas has been a dedicated organizer of symmetry meetings and editor of the periodical Symmetry. His enthusiasm has now spilled over into a 500-page book whose material is divided into five parts: Introductory chapters; Interdisciplinary Applications; ...
IEEE Transactions on Aerospace and Electronic Systems
A magnetic damping system for nanospacecraft attitude stabilization is proposed, based on the use... more A magnetic damping system for nanospacecraft attitude stabilization is proposed, based on the use of thin strips of amorphous Fe-B-Si soft magnetic ribbons. The size, number, and location of the strips is optimized, and a predictive formulation is provided. The main result of ground tests, comparing the performance of several soft magnetic materials, is that suitably heat-treated amorphous ribbons provide the best loss performance in the whole range of magnetic fields expected in orbit.
ABSTRACT We present a detailed rock-magnetic and archaeomagnetic study of two brick kilns, named ... more ABSTRACT We present a detailed rock-magnetic and archaeomagnetic study of two brick kilns, named OSA and OSB, discovered at the location of Osterietta, in northern Italy. The magnetic properties of representative samples have been investigated to identify the nature of the magnetic carriers, their domain state and thermal stability, and investigate their suitability for archaeomagnetic determinations. Thermally stable, mainly pseudosingle domain (PSD) magnetite is identified as the main magnetic carrier. The full geomagnetic field vector has been determined for the two kilns, including directional and intensity analysis. Archaeointensities have been recovered with both the classical Thellier and the multi-specimen protocols. The multi-specimen procedure was performed with a very fast-heating oven developed at Montpellier, France. A Matlab® code for anisotropy correction during the Thellier experiment is provided. The archaeointensity results obtained from both techniques for the OSA kiln are of high quality and in good mutual agreement. For the OSB kiln, Thellier results are characterized by large standard deviation and the multi-specimen (MSP) technique was not successful. The obtained full geomagnetic field vector (declination, inclination and intensity) has been used for the archaeomagnetic dating of the two structures suggesting that the OSA kiln was for the last time used between 1761?1841 A.D. and the OSB kiln between 1752?1831 A.D., at 95% probability. This study shows that intensity determinations do not restrict the dating results when referring to the last few centuries, as this period is characterized by very small intensity variations.
The potential of magnetic grain-size variations as an obsidian source characteristic is investiga... more The potential of magnetic grain-size variations as an obsidian source characteristic is investigated using geological and archaeological obsidians from five islands of the Mediterranean Sea: Lipari, Sardinia, Palmarola, Pantelleria, Melos. Four parameters are used: magnetic (χ) and anhysteretic (χa) susceptibilities, saturation isothermal remanent magnetizations at room (SIRM293) and liquid nitrogen (SIRM77) temperature. The ratio ST = SIRM77/SIRM293, which depends on the superparamagnetic grains relative abundance, varies little in each individual site, with the exception of Lipari which is characterized by large variations and the highest content of superparamagnetic grains. The χa vs. χ plot (King et al., 1982) shows some within-site dispersion of the samples; but the ratio Qa = χa/χ, which is strongly influenced by the single domain grains content, is characteristic for each site. The combined use of the King and Qa vs. ST plots discriminates the samples from most of the sites a...
Significant results are reported concerning the magnetic behavior of sintered soft ferrites and v... more Significant results are reported concerning the magnetic behavior of sintered soft ferrites and very thin Co-based amorphous ribbons up to 1 GHz. Conveniently field-annealed amorphous tapes can exhibit, in spite of their metallic character, superior combination of magnetic loss and permeability properties at all frequencies. Such properties are phenomenologically assessed through a physical approach based on the statistical theory of losses and the generalization of the related concept of loss separation, which takes into account different dissipation mechanisms and discriminates between domain wall and rotational processes. The latter, in particular, are described in ferrites in association with spin precession and damping and are given a formulation based on the Landau-Lifshitz-Gilbert equation and the assumption of distributed effective anisotropy fields.
Results on the production, structure and magnetic properties of (Fe100−xCox)73.5Cu1Nb3Si13.5B9 (x... more Results on the production, structure and magnetic properties of (Fe100−xCox)73.5Cu1Nb3Si13.5B9 (x = 0, 5, 10, 20) wires obtained by the in rotating water quenching technique, both in the amorphous and nanocrystalline state are reported. The obtained results are compared with that obtained for the FINEMET alloy. The saturation magnetostriction decreases when increasing the Co content in the amorphous wires and
The discovery and large scale investigation of rapidly solidified alloys have brought to light, i... more The discovery and large scale investigation of rapidly solidified alloys have brought to light, in the last two decades, a new scenario in basic and applied magnetism. With a range of compositions and microstructural states unavailable to conventional materials, the rapidly quenched alloys have in fact demonstrated unprecedented versatile properties, provided unique opportunities in applications and stirred up the domain
The dependence of structural properties of Fe (Si) 6. 5 wt.% ribbons on annealing treatments has ... more The dependence of structural properties of Fe (Si) 6. 5 wt.% ribbons on annealing treatments has been investigated in the temperature range 700-1300 °C. Two different annealing methods, respectively characterized by slow( ...
The effect of different melt temperature and of surface roughness on the magnetic properties of t... more The effect of different melt temperature and of surface roughness on the magnetic properties of the amorphous phase in Fe,,Co,,B,, alloy prepared by Planar Flow Casting (PFC) has been investigated. The obtained ribbons have been qagnetically characterized analyzing hysteresis loops and coercivity in the as-cast condition, after relaxation induced by field-annealing treatment and after thinning by chemical etching. Differential Scanning Calorimeter (DSC) has been used to quantitatively characterize structural relaxation and crystallization of the amorphous phase. Optical and Scanning Electron Microscopy (SEM) have been used to evaluate surface roughness. The average size of the surface grooves on the wheel side was found to increase with melt temperature and thickness. Magnetic properties have been observed to be mainly influenced by the roughness on the wheel side of the ribbons and surface frozen-in stresses are considered to be the main source for the magnetic anisotropy. Cryitallization process doesn't vary significantly among the samples, while relaxation heat was found to increase with thickness reduction. Melt temperature was related to previous remarks as controlling viscosity and thus modifying the wetting grade of the melt onto the cooling substrate. 0 1997 Elsevier Science S.A.
Rapidly solidified Fe-6. 5 wt% Si ribbons are fully ductile in the as-quenched state. However, th... more Rapidly solidified Fe-6. 5 wt% Si ribbons are fully ductile in the as-quenched state. However, the annealing process, required for optimization of the magnetic properties, generally leads to final brittle materials. In this article, a ...
Journal of Magnetism and Magnetic Materials 160 (1996) 151 153 H journal of N magnetism H and mag... more Journal of Magnetism and Magnetic Materials 160 (1996) 151 153 H journal of N magnetism H and magnetic H materials ELSEVIER The magnetic properties of FeSi 6.5 wt alloys obtained by a SiC14based CVD process S. CrottierCombe a, S. Audisio a, j. Degauque b, JL ...
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Papers by Enzo Ferrara
Keywords: Science and Peace, Science and Art, Lev Tolstoy, Aldous Huxley
Keywords: Science and Peace, Science and Art, Lev Tolstoy, Aldous Huxley