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2. Quantum applications based on the IBM QX platform

Author

POLÁK, Josef

Subjects
kvantový bit, IBM QX, quantum algorithm, kvantové algoritmy, kvantové výpočty, quantum computing, quantum bit
Abstract

This Bachelor thesis explores and clarifies the workings of quantum computer science. The first part of the work clarifies the fundamentals of quantum mechanics, which need to be known for understanding the following fundamentals of quantum informatics. In these bases are clarified expressions such as quantum bit, quantum logic gates, and many other properties of the quantum world (both positive and negative). The most famous algorithms, which are based on quantum computing, are also given for the idea. Another of the goals of the job is to explore and familiarize the IBM QX platform. You can learn about quantum circuits on this and use shared quantum computers in the cloud to run your own quantum circuits. The last part is the development of an application to solve the problem of the business traveller. An algorithm that works on a classical computer has been selected. Then quantum computing was plugged into an algorithm for acceleration. Finally, user interface creation followed. The application shows the workings of quantum computing rather than that it could be applicable in practice. Once redesigned, it could be used in logistics.

Published
2023

6. Integer- and Fractional-Order VCO Using Non-Inertial Amplitude Stabilization and Modern Active Elements

Author

Šotner, Roman, Petržela, Jiří, Jeřábek, Jan, Langhammer, Lukáš, Polák, Josef, Jaikla, Winai, Tuntrakool, Sunti, Šotner, Roman, Petržela, Jiří, Jeřábek, Jan, Langhammer, Lukáš, Polák, Josef, Jaikla, Winai, and Tuntrakool, Sunti

Abstract

This paper introduces design of the linearly tunable quadrature voltage-controlled oscillator (VCO) using modern off-the-shelf active elements suitable for the design of electronically adjustable applications. The simplified topology was achieved using non-inertial stabilization of amplitude. It allows targeting adjustability of the oscillation frequency only into lossless integrator part of the topology. This arrangement simplifies the design and the tenability also. Derived symbolical expressions indicate that gain adjustment of used amplifiers (that are still in single path) does not influence amplitude and phase shift ratio of generated waveforms, which is a beneficial feature. The performances of the circuit are tested experimentally in band of units of MHz and results confirmed expected behavior. Initial study of the oscillator with fractional-order capacitors is presented and discussed. Results are supported by laboratory measurements.

Published
2020

7. Design of Building Blocks for Fractional-Order Applications with Single and Compact Active Device

Author

Šotner, Roman, Jeřábek, Jan, Langhammer, Lukáš, Koton, Jaroslav, Polák, Josef, Andriukaitis, Darius, Valinevicius, Algimantas, Šotner, Roman, Jeřábek, Jan, Langhammer, Lukáš, Koton, Jaroslav, Polák, Josef, Andriukaitis, Darius, and Valinevicius, Algimantas

Abstract

This paper introduces new promising applications of VCA822 active device in the fractional-order design of two-ports including very simple and compact solutions of integrator, differentiator, low-pass and high-pass filter. Key feature of the designed circuits is their tunability controlled by current gain of VCA822 not available in case of solution with standard op-amps. Block (principal) structure of the device is explained in detail. PSpice simulation results of the designed circuits indicate usability of these ideas and also simple tunability of the application verified with a fractional-order constant phase element with the order alpha = 1/4.

Published
2020

8. Factors impacting startup sustainability in the Czech Republic

Author

Petrů, Naděžda, Pavlák, Miroslav, and Polák, Josef

Subjects
obchod, metody udržitelnosti, customer, marketingový management, zákazník, startup, marketing management, sustainability methods, Česká republika, business, Czech Republic
Abstract

The startup ecosystem in the Czech Republic falls far below the level of the developed economies of its Western neighbors. The startup map of the Czech Republic shows 1,717 continuously operating startups. And yet they have yet to receive priority attention in the academic realm. The primary goal of this article is to define the key factors of startup sustainability and to look for dependencies between them. The secondary goal is to identify the weaknesses of the Czech startup environment. The scientific hypotheses formulated focus on demonstrating the dependencies of selected factors influencing the startup sustainability. These have been verified on the basis of evaluation of data obtained via primary qualitative and quantitative research. Its findings were compared with the data of secondary research and with the conclusions of the scientific studies of international authors. The data were processed using statistical apparatus. Thanks to this research, the authors have identified in their conclusion the factors of the remote, immediate, and interior environments that can influence startup sustainability. They demonstrate a correlation between the level of strategic management and the quality of internal communications processes, between the capacities of startup management to manage relationships with customers (CRM) and to drive communications strategy, including brand support. In real practice, however, nine out of ten startups do not succeed. The reason is that their design fails to understand and address the needs of customers and lacks marketing and managed sales. Ekosystém startupů v České republice je hluboko pod úrovní vyspělých ekonomik západních sousedů. Vzhledem k tomu, že v ČR je registrováno 1 717 startupů, měla by se jim rovněž v akademické sféře věnovat pozornost. Primárním cílem tohoto článku je definovat klíčové faktory udržitelnosti startupů. Sekundárním cílem je identifikovat slabiny českého startupového prostředí. Formulované hypotézy se zaměřují na prokázání významu vybraných faktorů z hlediska jejich vlivu na udržitelnost startupů. Faktory byly ověřeny na základě vyhodnocení údajů získaných primárním kvalitativním a kvantitativním výzkumem. Výsledky primárního výzkumu byly porovnány s údaji sekundárního výzkumu a se závěry vědeckých studií zahraničních autorů. Data byla zpracována pomocí statistických metod. Díky tomuto výzkumu autoři ve svém závěru identifikovali faktory makro-, mezo- a mikroprostředí, které mohou ovlivnit udržitelnost startupů. Autoři prokazují korelaci mezi úrovní strategického řízení a kvalitou interních komunikačních procesů, mezi schopnostmi managementu v oblasti CRM a řízením komunikační strategie. Bylo zjištěno, že management startupů v naprosté většině nedokáže pochopit a řešit potřeby zákazníků a postrádá znalosti marketingu a managementu obchodních činností.

Published
2019

11. Current Challenges of Social Responsibility Best Practise in Foodstuff Production and Distribution Chain: Focus on Cee Countries

Author

Poláček, Lukáš, Vavřina, Jan, and Polák, Josef

Abstract

Corporate social responsibility in the food production and distribution sector in Europe is currently mainly linked to the activities of food banks. Food banks in the current form provide their services free of charge, however, these activities are closely associated with support from public budgets and volunteering. Currently, there is a growing tendency to revise the current funding scheme and the overall provision of food banks´ activities, as well as the efficiency aspects of their operation. It is, therefore, necessary to identify the essential aspects of the social responsibility framework, in particular from the side of participating entities as donors to food banks. The new situation calls for a revision of food banks´ operation schemes, including supportive voluntary intentions within the business environment. Specifically, the importance of the social responsibility of business entities can be seen in their inclusive assistance in the recent global COVID-19 crisis. This article aims at the identification of financial aspects behind voluntary donations to food banks, using the exploratory approach, namely via identification of major differences between voluntary donors and the respective industry benchmark in the field of financial criteria, focusing on Central and Eastern European countries (CEE). It was employed a methodological approach for testing independent observed samples to compare selected financial performance indicators´ mean values, using a two-sample T-test for equal and non-equal variances. Subsequently, a dynamic decomposition of observed financial performance indicators is conducted for a revision of the existence of mutual correlations. Differently from the main areas of interest of identified previous research on food banks´ activities, our effort is focusing on business entities in the role of food banks´ stakeholders. Corporate micro-financial data of foodstuff donors in Central and Eastern European countries according to their accessible annual reports and lists of donors to foodbanks are employed. Authors thus point out, based on provided empirical evidence, a need for a more inclusive type of attitude to food banks´ operations from the foodstuff production and distribution chain and its participants.

Published
2021
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38. Single-Ended Frequency Filter in Practical Realization with Digitally Adjustable Current Amplifier

Author

Polák, Josef and Langhammer, Lukáš

Subjects
DACA, MO-CF, frequency filter, controllable pole frequency
Abstract

This paper deals with proposed 2nd order universal frequency filter. In design of this frequency filter, multiple-output current follower (MO-CF) and digitally adjustable current amplifier (DACA) have been used. The frequency filter is proposed with ability to control the pole frequency without disturbing the selected quality factor by parameter of DACA active elements in form of integrated circuit. Design is supported by simulation and also measurement results.

Published
2016

39. Reconfigurable Fractional-Order Filter with Electronically Controllable Slope of Attenuation, Pole Frequency and Type of Approximation

Author

Jeřábek, Jan, Šotner, Roman, Dvořák, Jan, Polák, Josef, Kubánek, David, Herencsár, Norbert, Koton, Jaroslav, Jeřábek, Jan, Šotner, Roman, Dvořák, Jan, Polák, Josef, Kubánek, David, Herencsár, Norbert, and Koton, Jaroslav

Abstract

This paper presents design of electronically reconfigurable fractional-order filter that is able to be configured to operate as fractional-order low-pass filter (FLPF) or fractional-order high-pass filter (FHPF). Its slope of attenuation between pass band and stop band, i.e. order of the filter, is electronically adjustable in range between 1 and 2. Also pole frequency can be electronically controlled independently with respect to other tuned parameters. Moreover, particular type of approximation can be also controlled electronically. This feature set is available both for FLPF and FHPF type of response. Presented structure of the filter is based on well-known follow-the-leader feedback (FLF) topology adjusted in our case for utilization with just simple active elements operational transconductance amplifiers (OTAs) and adjustable current amplifiers (ACAs), both providing possibility to control its key parameter electronically. Paper explains how reconfigurable 3rd-order FLF topology is used in order to approximate both FLPF and FHPF in concerned frequency band of interest. Design is supported by PSpice simulations for three particular values of order of the filter (1.25, 1.5, 1.75), for several values of pole frequency and for two particular types of approximation forming the shape of both the magnitude and phase response. Moreover, theoretical presumptions are successfully confirmed by laboratory measurements with prepared prototype based on behavioral modeling.

Published
2017

40. A CMOS Multiplied Input Differential Difference Amplifier: A New Active Device and Its Applications

Author

Šotner, Roman, Jeřábek, Jan, Prokop, Roman, Kledrowetz, Vilém, Polák, Josef, Šotner, Roman, Jeřábek, Jan, Prokop, Roman, Kledrowetz, Vilém, and Polák, Josef

Abstract

This paper presents a newly developed active device, referred to as a multiplied input differential difference amplifier (MIDDA), which allows operations of summation/subtraction and multiplication of input signals. It was designed and fabricated using I3T25 0.35 um ON (ON Semiconductor, Phoenix, AZ, USA) Semiconductor technology. The achieved results, which describe the experimentally verified behaviour of the fabricated device, are introduced, as well as the simple applications of MIDDA with electronically controllable parameters, useful for analogue signal processing. Moreover, the paper discusses an interesting example of nonlinear application to a double-sideband amplitude modulator, based on the utilization of multiplication and summation of particular signals. The laboratory experimental results which are achieved through the use of a fabricated prototype (both in time and frequency domain), confirm the workability of the concept., Tento článek prezentuje nově vyvinutý aktivní prvek nazvaný zesilovač s násobením a součtově-rozdílovými operacemi (multiplied input differential difference amplifier - MIDDA), který dovoluje sečíst/odečíst a násobit vstupní signály dle definovaných vztahů. Prvek byl navržen v technologii ON Semiconductor I3T25 0.35 um. Získané výsledky popisují experimentálně ověřené chování vyrobeného zařízení stejně jako jednoduché aplikace MIDDA využívající elektronického řízení parametrů prvku. Mimo to článek rozebírá taktéž zajímavý příklad nelineární aplikace – AM modulátor s nosnou a oběma postranními pásmy, který je založen na využití dostupných operací násobení a sčítání specifických signálů. Laboratorní experimenty s vyrobeným prototypem v časové a kmitočtové oblasti potvrzují provozuschopnost konceptů.

Published
2017

41. Resistor-less Single-purpose or Reconfigurable Biquads Utilizing Single Z-Copy Controlled-Gain Voltage Differencing Current Conveyor

Author

Jeřábek, Jan, Šotner, Roman, Polák, Josef, Langhammer, Lukáš, Herencsár, Norbert, Prokop, Roman, Vrba, Kamil, Jeřábek, Jan, Šotner, Roman, Polák, Josef, Langhammer, Lukáš, Herencsár, Norbert, Prokop, Roman, and Vrba, Kamil

Abstract

Presented work deals with applications of the single Z-Copy Controlled-Gain Voltage Differencing Current Conveyor (ZC-CG-VDCC) in single purpose and multifunctional biquadratic voltage- and current-mode active resistor-less filters. Electronically adjustable features of the active device (intrinsic current input resistance Rx, current gain B and transconductance gm) are controlled by DC bias current. These mentioned adjustable features allow interesting possibilities of control of the pole frequency and quality factor. Four voltage-mode solutions realizing low-pass, band-pass, high-pass and band-reject filtering solutions were designed together with two current-mode filters. The current-mode solutions have curious multifunctional capability based on full utilization of electronically controllable parameters of the ZC-CG-VDCC. Two adjustable parameters of the ZC-CG-VDCC (intrinsic current input resistance and transconductance) are used for electronic setting of features of the filter (pole frequency, quality factor, tuning). Control of the third adjustable parameter (current gain) causes reconnection-less change of the transfer function between iAP (inverting all-pass response) and iBR (inverting band-reject responses). Simulation results in PSPICE and Cadence CDS 6 are used to show characteristics of the proposed circuits.

Published
2017

44. Herbář funkcí

Author

Čepička, Jan, Girg, Petr, Nečesal, Petr, and Polák, Josef

Subjects
graphs, function, množina, set, funkce, grafy
Published
2015

45. Tunable fully-differential filter employing MOTA and DACA elements

Author

Langhammer, Lukáš, Jeřábek, Jan, Polák, Josef, Šotner, Roman, Štork, Petr, Langhammer, Lukáš, Jeřábek, Jan, Polák, Josef, Šotner, Roman, and Štork, Petr

Abstract

A new fully-differential (F-D) filtering structure of the 2nd-order current-mode universal filter is described in this paper. Presented filter is also proposed in a single-ended (S-E) form in order to compare behavior of single-ended and fully-differential structures. Signal-flow graphs method is used to design both presented filters. Multi-output transconductance amplifiers (MOTAs), digitally adjustable current amplifier (DACA), multi-output current follower (MO-CF) and fully differential current follower (FD-CF) were used in proposal. Filters possess of ability to adjust their pole frequency and quality factor independently of each other. The actual function of proposed filters has been verified by PSpice simulations and experimental measurements.

Published
2016

46. Dual-parameter control of the pole frequency in case of universal filter with MCDU elements

Author

Jeřábek, Jan, Šotner, Roman, Herencsár, Norbert, Polák, Josef, Dvořák, Jan, Koton, Jaroslav, Jeřábek, Jan, Šotner, Roman, Herencsár, Norbert, Polák, Josef, Dvořák, Jan, and Koton, Jaroslav

Abstract

This paper presents an universal filter with control of the pole frequency by two mutually independent parameters - current gain (B) and intrinsic resistance (R x) in frame of two modified current differencing unit (MCDU) active elements. This type of control extends and also improves features of the tuning range and is referred to as dual-parameter control. The current-mode filter is of the second order and the required type of the response (low pass, inverting band pass, high pass, band reject and all pass) is obtained by proper selection/combination of input(s) - this filter is of the multiple-input single-output type. The filter employs two capacitors, two MCDUs, each of them with four controllable parameters and one multiple-output current follower. The paper includes tuning range analysis, the simulation results with behavioral models and also laboratory measurement results with the same models. Moreover, designed transistor-level structures of both the active elements proposed in ON Semiconductor I3T CMOS 0.35 um technology that were used for final simulations confirm the workability and features of the designed concept., Tento článek představuje univerzální filtr s řízením frekvence pólu pomocí dvou nezávislých parametrů - proudové zesílení (B) a vnitřní odpor (Rx) v rámci dvou modifikovaných proudových diferenčních jednotek (MCDU). Tento typ kontroly rozšiřuje a také zlepšuje vlastnosti rozsah ladění a je označován jako dual-parameter řízení. Filtr je druhého řádu, pracuje v proudovém módu a požadovaný typ odezvy (dolní propust, invertující pásmová propust, horní propust, pásmová zádrž a fázovací článek) se získá správným výběrem/kombinací vstupu(ů) - Tento filtr je typu více vstupů - jeden výstup. Filtr používá dva kondenzátory, dva prvky MCDU, každý z nich se čtyřmi nastavitelnými parametry a jeden vícevýstupový proudový sledovač. Článek obsahuje analýzu optimalizace rozsahu ladění, výsledky simulace s behaviorální modely a také výsledky laboratorního měření se stejnými modely. Navíc, aktivní prvky byly navrženy i na tranzistorové úrovni v ON Semiconductor I3T CMOS 0,35 um technologii. Tyto modely byly použity pro finální simulace, které potvrdily funkčnost a vlastnosti navržené koncepce.

Published
2016

47. Digitally Controllable Current Amplifier and Current Conveyors in Practical Application of Controllable Frequency Filter

Author

Polák, Josef, Jeřábek, Jan, Langhammer, Lukáš, Šotner, Roman, Dvořák, Jan, Pánek, David, Polák, Josef, Jeřábek, Jan, Langhammer, Lukáš, Šotner, Roman, Dvořák, Jan, and Pánek, David

Abstract

This paper presents the simulations results in comparison with the measured results of the practical realization of the multifunctional second order frequency filter with a Digitally Controlled Current Amplifier (DACA) and two Dual-Output Current-Controlled Current Conveyors (CCCII +/). This filter is designed for use in current mode. The filter was designed of the single input multiple outputs (SIMO) type, therefore it has only one input and three outputs with individual filtering functions. DACA element used in a newly proposed circuit is present in form of an integrated chip and the current conveyors are implemented using the Universal Current Conveyor (UCC) chip with designation UCC-N1B. Proposed frequency filter enables independent control of the pole frequency using parameters of two current conveyors and also independent control of the quality factor by change of a current gain of DACA.

Published
2016

48. Reconnection-Less Electronically Reconfigurable Filter with Adjustable Gain Using Voltage Differencing Current Conveyor

Author

Jeřábek, Jan, Šotner, Roman, Polák, Josef, Vrba, Kamil, Dostál, Tomáš, Jeřábek, Jan, Šotner, Roman, Polák, Josef, Vrba, Kamil, and Dostál, Tomáš

Abstract

This paper presents a novel reconnection-less and electronically reconfigurable analogue filter. It employs two active elements, Voltage-Differencing Current Conveyor (VDCC) and Dual-Output Current Amplifier (DO-CA) with two independently tunable gains. Filter has the single input and single output topology (SISO). The current-mode transfer function of the filter can be tuned electronically from the low-pass (LP) response to the high-pass (HP) response, via the band-stop (BS) response, without reconnection of the input or output terminal. It is designed in order to provide tuning of both the stop-band gain and also pass-band gain of all the transfer functions, because also transfer functions with additional and intended zero in transfer function are available. The theoretical presumptions are confirmed by both simulations and lab measurements with available devices.

Published
2016

49. Perception of Commercial Risk at Exporting to China

Author

Polák, Josef

Subjects
China, Kruskal-Wallis Test, Exporting Companies, Export, Commercial Risk
Abstract

Purpose of the article: The general conception of risk associated with the international trade and risk classification bear the same patterns, however, as far as the commercial risk is involved, the particular definition of commercial risk is lacking. This paper aims to provide the results of primary research on the commercial risks for export to the People’s Republic of China (China). China and its mutual trade balance with the Czech Republic confirm its position not only in the Czech exporting strategy, but also globally, on the world market. Methodology/methods: Data from the primary research were obtained by questionnaire survey and by semistructured interview. Data were statistically analyzed using the Kruskal-Wallis test and the Wilcoxon test. Furthermore, the content analysis was used to evaluate the interview. Scientific aim: The scientific aim of the article was to present statistical data analysis of primary research focused on perception of commercial risk at exporting to China. Statistically validated data are important in order to determine the probability distribution of commercial risk, which will be the basis for a statistical model evaluation of commercial risks for the Czech exporting companies to China. The results of this research article will be used for future creating a model commercial risk evaluation. Findings: The obtained data were divided into groups according to the sizes of subjects. These groups were statistically tested and evaluated. It can be stated that only in the group of medium-sized enterprises have been identified substantial differences in the perception of commercial risk according these results. Conclusions: Statistical analysis demonstrated that the data obtained from a group of large and all companies show the same distribution function for all selections. Therefore, these data can draw conclusions and use them to build a statistical model of commercial risks evaluation.

Published
2014

50. Behavioral modeling of Digitally Adjustable Current Amplifier

Author

Polák, Josef, Langhammer, Lukáš, Jeřábek, Jan, Polák, Josef, Langhammer, Lukáš, and Jeřábek, Jan

Abstract

This article presents the digitally adjustable current amplifier (DACA) and its analog behavioral model (ABM), which is suitable for both ideal and advanced analysis of the function block using DACA as active element. There are four levels of this model, each being suitable for simulation of a certain degree of electronic circuits design (e.g. filters, oscillators, generators). Each model is presented through a schematic wiring in the simulation program OrCAD, including a description of equations representing specific functions in the given level of the simulation model. The design of individual levels is always verified using PSpice simulations. The ABM model has been developed based on practically measured values of a number of DACA amplifier samples. The simulation results for proposed levels of the ABM model are shown and compared with the results of the real measurements of the active element DACA., Tento článek představuje digitálně nastavitelný proudový zesilovač (DACA) a jeho analogový behaviorální model (ABM), který je vhodný jak pro ideální tak pokročilé analýzy funkčního bloku používajícího Daca jako aktivní prvek. K dispozici jsou čtyři úrovně tohoto modelu, z nichž každá je vhodná pro simulaci určitého stupně elektronických obvodů (např filtry, oscilátory, generátory). Každý model je prezentován pomocí schematického zapojení v simulačního programu OrCAD, včetně popisu rovnic, které představují konkrétní funkce v dané úrovni simulačního modelu. Návrh jednotlivých úrovní je vždy ověřen pomocí PSpice simulací. Model ABM byl vyvinut na základě prakticky naměřených hodnot několika vzorcích Daca zesilovače. Výsledky simulací pro návržených úrovní modelu ABM jsou zobrazeny a porovnány s výsledky reálného měření aktivního prvku DACA.

Published
2015

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