Financial distress and ownership structure: The case of Serbia

The main objective of our research is to examine the effects of financial distress on ownership structure and to elaborate on the factors that influence change of ownership in companies that have adopted a reorganisation plan in the Republic of Serbia. Of the 63 sample companies reorganised in bankruptcy proceedings between 2009 and 2015, the ownership structure remained unchanged in 49 companies, while in 35, the existing owners or their family members remained in charge of key management positions. Using binary logistic regression, we observed that two factors influenced the change in ownership structure: the length of time it takes to resolve the insolvency process and whether the owners were involved in the running of the distressed company before it filed for bankruptcy. The obtained results indicate that corporate governance mechanisms in distressed Serbian companies are not efficient

Reflection and transmission of high-frequency acoustic, electromagnetic and elastic waves at a distinguished class of irregular, curved boundaries

Reflection and transmission phenomena associated with high-frequency linear wave incidence on irregular boundaries between adjacent acoustic or electromagnetic media, or upon the irregular free surface of a semi-infinite elastic solid, are studied in two dimensions. Here, an ‘irregular’ boundary is one for which small-scale undulations of an arbitrary profile are superimposed upon an underlying, smooth curve (which also has an arbitrary profile), with the length scale of the perturbation being prescribed in terms of a certain inverse power of the large wave-number of the incoming wave field. Whether or not the incident field has planar or cylindrical wave-fronts, the associated phase in both cases is linear in the wave-number, but the presence of the boundary irregularity implies the necessity of extra terms, involving fractional powers of the wave-number in the phase of the reflected and transmitted fields. It turns out that there is a unique perturbation scaling for which precisely one extra term in the phase is needed and hence for which a description in terms of a Friedlander–Keller ray expansion in the form as originally presented is appropriate, and these define a ‘distinguished’ class of perturbed boundaries and are the subject of the current paper

Friedlander-Keller ray expansions in electromagnetism: Monochromatic radiation from arbitrary surfaces in three dimensions

The standard approach to applying ray theory to solving Maxwell’s equations in the large wave-number limit involves seeking solutions that have (i) an oscillatory exponential with a phase term that is linear in the wave-number and (ii) has an amplitude profile expressed in terms of inverse powers of that wave-number. The Friedlander–Keller modification includes an additional power of this wave-number in the phase of the wave structure, and this additional term is crucial when analysing certain wave phenomena such as creeping and whispering gallery wave propagation. However, other wave phenomena necessitate a generalisation of this theory. The purposes of this paper are to provide a ‘generalised’ Friedlander–Keller ray ansatz for Maxwell’s equations to obtain a new set of field equations for the various phase terms and amplitude of the wave structure; these are then solved subject to boundary data conforming to wave-fronts that are either specified or general. These examples specifically require this generalisation as they are not amenable to classic ray theory

Continuous-Time Delta-Sigma Modulators for Ultra-Low-Power Radios

The modern small devices of today require cheap low power radio frequency (RF) transceivers that can provide reliable connectivity at all times. In an RF transceiver, the analog-to-digital converter (ADC) is one of the most important parts and it is also one of the main power consumers. There are several architectures for implementing an ADC, but in the last decade, continuous-time Delta-Sigma modulators (CT DSMs) have become popular due to their potential of achieving low power consumption and the inherent anti-alias filtering. This thesis investigates different implementations of CT DSMs intended for an ultra-low-power (ULP) receiver operating in the 2.45 GHz ISM band. The main focus is on power saving techniques and jitter insensitive solutions. Papers I and II present a CT DSM with dual switched-capacitor-resistor (DSCR) feedback used in the first DAC. This technique has been developed for the purpose of reducing the jitter sensitivity of the CT DSM while keeping the DAC peak current lower than for conventional SCR feedback. A lower peak current translates into more relaxed slew-rate requirements on the first operational amplifier and thereby less power consumption. Papers III and IV present a low power 2nd-order CT DSM with one operational amplifier. The main objective was to reduce the power consumption of the usually more critical analog part while still achieving a 2nd-order noise shaping. The thesis also examines the possibility of using a successive approximation register (SAR) quantizer instead of the commonly used flash quantizer to reduce the power consumption of the digital part as well

Asymptotic Expansions of Solutions To The Helmholtz and Maxwell’s Equations Advancements in Ray Theory

The standard approach to ray theory in solving the Helmholtz and Maxwell’s equations in the short wave limit involves seeking solutions that have (i) an oscillatory exponential with a phase term linear in the wavenumber and (ii) have an amplitude profile expressed in terms of inverse powers of the wavenumber. The Friedlander-Keller ray expansion includes an additional variable term within the phase of the wave structure; this new exponent term is proportional to a specific power of the wavenumber. However, many wave phenomena require a generalisation of the Friedlander-Keller ray expansion. The work presented within this thesis provides physical motivations requiring generalised ray expansions of exponential terms of fractional order for the ansatz of the solutions of the Helmholtz, Navier’s, and Maxwell’s equations. Furthermore, it derives a new set of field equations for the new wave structure’s individual exponent and amplitude terms. It then solves those equations subject to provided data conforming to arbitrary general boundaries. To demonstrate the applicability of the generalised ray theory, this thesis also presents classes of wave phenomena associated with high-frequency reflection, refraction, and radiation within a two or three-dimensional medium, which is either homogeneous or inhomogeneous

Asymptotic Expansions of Solutions To The Helmholtz and Maxwell’s Equations Advancements in Ray Theory

The standard approach to ray theory in solving the Helmholtz and Maxwell’s equations in the short wave limit involves seeking solutions that have (i) an oscillatory exponential with a phase term linear in the wavenumber and (ii) have an amplitude profile expressed in terms of inverse powers of the wavenumber. The Friedlander-Keller ray expansion includes an additional variable term within the phase of the wave structure; this new exponent term is proportional to a specific power of the wavenumber. However, many wave phenomena require a generalisation of the Friedlander-Keller ray expansion. The work presented within this thesis provides physical motivations requiring generalised ray expansions of exponential terms of fractional order for the ansatz of the solutions of the Helmholtz, Navier’s, and Maxwell’s equations. Furthermore, it derives a new set of field equations for the new wave structure’s individual exponent and amplitude terms. It then solves those equations subject to provided data conforming to arbitrary general boundaries. To demonstrate the applicability of the generalised ray theory, this thesis also presents classes of wave phenomena associated with high-frequency reflection, refraction, and radiation within a two or three-dimensional medium, which is either homogeneous or inhomogeneous