International tourism is one of the most important sectors of the open economy. The aim of this paper is to investigate the effects that income as gross domestic product, tourism price as the real exchange rate, and travel cost as the price of Brent crude oil have on inbound tourism demand (tourist arrivals) from Poland, Slovakia, Germany, and Austria in the South Moravian Region of the Czech Republic over the period 2002:M1–2018:M5. The number of Polish, German, Slovak and Austrian tourists accommodated in collective accommodation establishments within the South Moravian Region as a dependent variable are considered. To achieve this aim, cointegration analysis under the VECM approach is applied. The results show that Slovak, Polish, Austrian and German tourists respond positively to their income changes. Austrian and Slovak tourists respond negatively to changes in tourism prices in the Czech Republic. Tourists from Germany and Poland do not respond to changes in the Czech price level since their elasticity coefficients are non-significant. German, Austrian and Slovak tourists respond negatively to transportation cost changes. Polish tourists do not respond to transport cost changes since their elasticity coefficient is non-significant.
In connection with the earlier article published in 2012 which discussed the hoard of 57 Prague grossi discovered between March 2010 and May 2012 in the field to the north of Stará Boleslav – a historical city and a pilgrimage place situated about 20km to the north-east of Prague – the author presents the missing part of the hoard which was not published in the original article. It includes twelve Prague grossi and four parvi struck under John of Luxembourg. With these additional coins, the entire hoard covers thirteen previously known varieties of the Prague grossi and adds one new variety (no. 11 in the survey table). In order to determine the approximate burial date of the hoard, the author takes into account the assumed production period of the latest variety – Castelin VIII. 47 – and concludes that the hoard could have been buried at some point during the late 1340s or early 1350s. As for the actual reason of depositing, common form of money thesaurisation is assumed, most likely by a resident of Stará Boleslav or a pilgrim visiting the town. At the time of the assumed depositing, the place had already played a role of an important pilgrimage centre for several centuries.
Roman Sotner, Jan Jerabek, Norbert Herencsar, Roman Prokop, Abhirup Lahiri, Tomas Dostal and Kamil Vrba
Presented research introduces active filtering circuits which allow change of the transfer type without necessity of reconnection of the input or output terminal that can be very useful for on-chip applications. Our attention is focused on simple first-order filters that allow high-pass response (HP), all-pass response (AP) and also direct transfer (DT) with constant magnitude and phase characteristics between two terminals (input and output) by adjusting of one controllable parameter (current gain B in our case). Useful modification of the well-known current follower transconductance amplifier (CFTA), the so-called Z-copy current-controlled current follower differential input transconductance amplifier (ZC-CCCFDITA) and adjustable current amplifier were utilized in these circuits. Interesting possibilities (crossing between several transfer functions) of presented circuits require different values of B to obtain desired transfer function that is very important for practice and selection of specific way of control. Requirements on value of this continuously controllable gain B differ among presented structures. Theory is supported by simulation and measurement results with behavioral models utilizing commercially available active elements and simulation results with active elements based on CMOS models.
Roman Šotner, Norbert Herencsár, Jan Jeřábek, Radek Dvořák, Aslihan Kartci, Tomáš Dostál and Kamil Vrba
In this paper, a new electronically tunable quadrature oscillator (ETQO) based on two modified versions of current feedback amplifiers (CFAs), the so called double current controlled CFA (DCC-CFAs) is presented. The frequency of oscillation (FO) of the proposed voltage-mode (VM) ETQO is electronically adjustable by current gain or by varying the intrinsic resistance of the X terminal of the active element used. The condition of oscillation (CO) is adjustable by current gain independently with respect to frequency of oscillation. Simultaneous control of current gain and intrinsic resistance allows linear control of FO and provides extension of frequency tuning range. In the proposed circuit all the capacitors are grounded. The use of only grounded capacitors makes the proposed circuit ideal for integrated circuit implementation. The presented active element realized by using BiCMOS technology and the behavior of proposed circuit are discussed in details. The theoretical results are verified by SPICE simulations based on CMOS ON-Semi C5 0.5 μm and bipolar ultra high frequency transistor arrays Intersil HFA 3096 process parameters.
Roman Sotner, Jan Jerabek, Norbert Herencsar, Jiun-Wei Horng, Kamil Vrba and Tomas Dostal
This work presents an example of implementation of electronically controllable features to an originally unsuitable circuit structure of oscillator. Basic structure does not allow any electronic control and has mutually dependent condition of oscillation (CO) and frequency of oscillation (FO) if only values of passive elements are considered as the only way of control. Utilization of electronically controllable current conveyor of second generation (ECCII) brings control of CO independent of FO. Additional application of voltage amplifier with variable gain in both polarities (voltage-mode multiplier) to feedback loop allows also important enlargement of the range of the independent FO control. Moreover, our proposal was tested and confirmed experimentally with commercially available active elements (“Diamond transistor”, current-mode multiplier, voltage-mode multiplier) in working range of tens of MHz.
R. Sotner, J. Jerabek, N. Herencsar, K. Vrba, A. Lahiri and T. Dostal
The paper deals with precise analysis of simple AC variable gain CMOS amplifier. The circuit can be used as a simple voltage follower (6 MOS transistors are required) or amplifier. The main attention of this work is focused on a small-signal model of the proposed block and effects of additional passive network leading to compensation of its instability. The continuous gain adjusting in range from 1.1 to 10 (0.8 – 20 dB and with bandwidth 4.9 - 90 MHz at 5 pF load capacitance) is possible and the proposed amplifier is suitable for implementation in systems, where lower range of gain adjusting and large dynamical range is required. Theoretical analyses are supported by PSpice simulations (TSMC 0.18 um technological models) and experimental measurements with commercially available CMOS transistor fields (ALD1106/7) also confirm the discussed behavior of the amplifier.