Observational detection of meteor-produced VLF electromagnetic radiation

In November 1998, Croatian Physical Society's expedition to Mongolia was undertaken. The goal was to make measurements of the puzzling electrophonic sounds and very low frequency (VLF) radio emission from meteors during the anticipated Leonid meteor storm. During the night of 16/17 November 1998, an extremely high fireball activity of the Leonid meteors occured. During this period, we performed measurements of the VLF radiation from meteors. Here we present a positive signal which consists of a sequence of sharp, short VLF bursts, coincident with the appearance of meteor that was recorded by the video camera. This is the first completely controlled instrumental recording of such an event

Opažanje niskofrekventnog elektromagnetskog zračenja proizvedenog meteorom

In November 1998, Croatian Physical Society\u27s expedition to Mongolia was undertaken. The goal was to make measurements of the puzzling electrophonic sounds and very low frequency (VLF) radio emission from meteors during the anticipated Leonid meteor storm. During the night of 16/17 November 1998, an extremely high fireball activity of the Leonid meteors occured. During this period, we performed measurements of the VLF radiation from meteors. Here we present a positive signal which consists of a sequence of sharp, short VLF bursts, coincident with the appearance of meteor that was recorded by the video camera. This is the first completely controlled instrumental recording of such an event.Ekspedicija Hrvatskog fizikalnog društvo uputila se u Mongoliju u studenom 1998 radi promatranja očekivane kiše meteora i mjerenja neobičnih elektrofonskih šumova i niskofrekventnog elektromagnetskog zračenja proizvedenog meteorima. U noći 16/17 studenog 1998. došlo je do izrazito pojačane aktivnosti sjajnih meteora Leonida. U tom smo periodu mjerili elektromagnetske valove VLF i istovremeno snimali meteore. Ovdje izvješćujemo o zabilježenom signalu elektromagnetskih valova koji se sastojao od niza kratkotrajnih niskofrekventnih impulsa, koji se pojavio istovremeno s meteorom. Ovo je prvo instrumentalno bilježenje te pojave načinjeno u potpuno kontroliranim uvjetima

Observational detection of meteor-produced VLF electromagnetic radiation

In November 1998, Croatian Physical Society's expedition to Mongolia was undertaken. The goal was to make measurements of the puzzling electrophonic sounds and very low frequency (VLF) radio emission from meteors during the anticipated Leonid meteor storm. During the night of 16/17 November 1998, an extremely high fireball activity of the Leonid meteors occured. During this period, we performed measurements of the VLF radiation from meteors. Here we present a positive signal which consists of a sequence of sharp, short VLF bursts, coincident with the appearance of meteor that was recorded by the video camera. This is the first completely controlled instrumental recording of such an event

Global Jacquet-Langlands correspondence, multiplicity one and classification of automorphic representations

In this paper we show a local Jacquet-Langlands correspondence for all unitary irreducible representations. We prove the global Jacquet-Langlands correspondence in characteristic zero. As consequences we obtain the multiplicity one and strong multiplicity one theorems for inner forms of GL(n) as well as a classification of the residual spectrum and automorphic representations in analogy with results proved by Moeglin-Waldspurger and Jacquet-Shalika for GL(n).Comment: 49 pages; Appendix by N. Grba

Convexity Adjustment for Constant maturity Swaps in a Multi-Curve Framework

In this paper we propose a double curving setup with distinct forward and discount curves to price constant maturity swaps (CMS). Using separate curves for discounting and forwarding, we develop a new convexity adjustment, by departing from the restrictive assumption of a flat term structure, and expand our setting to incorporate the more realistic and even challenging case of term structure tilts. We calibrate CMS spreads to market data and numerically compare our adjustments against the Black and SABR (stochastic alpha beta rho) CMS adjustments widely used in the market. Our analysis suggests that the proposed convexity adjustment is significantly larger compared to the Black and SABR adjustments and offers a consistent and robust valuation of CMS spreads across different market conditions

A construction of residues of Eisenstein series and related square-integrable classes in the cohomology of arithmetic groups of low kk-rank

The cohomology of an arithmetic congruence subgroup of a connected reductive algebraic group defined over a number field is captured in the automorphic cohomology of that group. The residual Eisenstein cohomology is by definition the part of the automorphic cohomology represented by square-integrable residues of Eisenstein series. The existence of residual Eisenstein cohomology classes depends on a subtle combination of geometric conditions (coming from cohomological reasons) and arithmetic conditions in terms of analytic properties of automorphic L-functions (coming from the study of poles of Eisenstein series). Hence, there are almost no unconditional results in the literature regarding the very existence of non-trivial residual Eisenstein cohomology classes. In this paper, we show the existence of certain non-trivial residual cohomology classes in the case of the split symplectic, and odd and even special orthogonal groups of rank two, as well as the exceptional group of type $G_2$, defined over a totally real number field. The construction of cuspidal automorphic representations of $GL_2$ with prescribed local and global properties is decisive in this context

D-mannitol for medium temperature thermal energy storage

D-mannitol is a sugar alcohol with a melting temperature of approximately 167 °C. It has been identified as a phase change material for storing heat at a temperature range of about 150-180 °C. The outcome of the published research on its applicability for this purpose is inconsistent and sometimes contradictory. We identified that there is a need for further study on the material to overcome such uncertainty. Thus we conducted a series of thermal measurements to quantify its properties and suitability for a phase change thermal storage. Our differential scanning calorimetric measurements showed that the material has a melting temperature of 167 °C and fusion heat of 297 kJ/kg. However, our accelerated thermal cycling test revealed that this value decreases logarithmically to 249 and 240 kJ/kg after 100 and 200 cycles respectively. The material shows a significant level of sub-cooling in DSC measurement with a solidification temperature of approximately 110-120 °C which can render the material unsuitable for thermal storage purposes. However, our secondary measurement with a large quantity of D-mannitol shows that such level of sub-cooling is unlikely to occur in a macro-scale sample. We built and tested a thermal storage system containing 3.8 kg of D-mannitol to investigate its performance in larger quantities and evaluate the heat transfer properties of the heat exchanger mechanism in the storage system. We show that the material releases significant heat when it is cooled down to 150 °C which means implies the occurrence of solidification at a temperature above 150 °C