Application of Break-Even Point Analysis

The determination of Break-even point represents the important information for the enterprise because it defines the minimum amount of products that enterprise needs to produce for cover their fixed and variable costs. Knowing the Break-even point allows enterprise to properly estimate revenues necessary to ensure profits. In this paper, authors deal with the identifying Break-even point and indicate a model example of its calculation

Test of the maximum penetration depth of the Roteg GPR above the Hranice Abyss and in the Moravian Karst

A new kind of Ground Penetrating Radar (GPR) ”Roteg“ was tested at generally known speleological sites in the Czech Republic. The first examined site – the Hranice Abyss located in the Hranice Karst – is the deepest underwater cave in the world.This GPR is characterised by much higher pulse power, antennas with rather high voltage (5–15 kV), and, in particular, the special design of the pulse generator.The radar survey near the Hranice Abyss has shown that it is possible to detect reflections of electromagnetic pulses coming from the speleogenic structures of the abyss itself and from lithological boundaries occurring below the water table – something which was not anticipated and was verified for the first time ever. Plausibly detectable reflections were detected from the depths of 580 m below the surface – which is approximately 515 m below the water level – using the longest available 6-metre antennas tuned to the frequency of 25 MHz.The second site tested was the quarry of Malá dohoda near the municipality of Holštejn, the Moravian Karst, the Czech Republic. The GPR used was the same as above except the power output to the transmitting antenna which produced pulses of 20 kV. The radarogram showed cavities located at the depth of up to 300 m, the layers on the boundary between Lažánky and Vilémovice members of limestone at the depth of 400 m, basement sandstones and conglomerates at the depth of 600–700 m, and granite rocks below this level.Both of the tests mentioned above confirmed the extraordinary big penetration depth of the GPR signal which exceeded 500 m when using the maximum power on transmitting antennas

MTMonkey: A Scalable Infrastructure for a Machine Translation Web Service

We present a web service which handles and distributes JSON-encoded HTTP requests for machine translation (MT) among multiple machines running an MT system, including text pre- and post processing. It is currently used to provide MT between several languages for cross-lingual information retrieval in the Khresmoi project. The software consists of an application server and remote workers which handle text processing and communicate translation requests to MT systems. The communication between the application server and the workers is based on the XML-RPC protocol. We present the overall design of the software and test results which document speed and scalability of our solution. Our software is licensed under the Apache 2.0 licence and is available for download from the Lindat-Clarin repository and Github

Graph sharing games: complexity and connectivity

We study the following combinatorial game played by two players, Alice and Bob, which generalizes the Pizza game considered by Brown, Winkler and others. Given a connected graph G with nonnegative weights assigned to its vertices, the players alternately take one vertex of G in each turn. The first turn is Alice's. The vertices are to be taken according to one (or both) of the following two rules: (T) the subgraph of G induced by the taken vertices is connected during the whole game, (R) the subgraph of G induced by the remaining vertices is connected during the whole game. We show that if rules (T) and/or (R) are required then for every epsilon > 0 and for every positive integer k there is a k-connected graph G for which Bob has a strategy to obtain (1-epsilon) of the total weight of the vertices. This contrasts with the original Pizza game played on a cycle, where Alice is known to have a strategy to obtain 4/9 of the total weight. We show that the problem of deciding whether Alice has a winning strategy (i.e., a strategy to obtain more than half of the total weight) is PSPACE-complete if condition (R) or both conditions (T) and (R) are required. We also consider a game played on connected graphs (without weights) where the first player who violates condition (T) or (R) loses the game. We show that deciding who has the winning strategy is PSPACE-complete.Comment: 22 pages, 11 figures; updated references, minor stylistical change

Flow Inside the Sidewall Gaps of Hydraulic Machines: A Review

The paper critically reviews the current state of the art in flow inside sidewall gaps of hydraulic pumps and turbines. It describes the consequences of the presence of this type of flow in turbomachinery and then relates it to other physical phenomena that determine the behavior, operating characteristics, and overall performance of the machine. Despite the small dimensions of the rotor-stator spaces, the flow in these regions can significantly affect the overall flow field and, consequently, efficiency. The circulation of the fluid inside the gaps and secondary flow that is caused by rotating elements influences the disk friction losses, which is of great importance, especially in the case of low specific speed pumps and turbines. The flow pattern affects the pressure distribution inside a machine and, thus, generates axial thrust. The presence of secondary flow also significantly changes the rotordynamics and can bring about undesirable vibrations and acoustics issues. This article aims to review and summarize the studies that were conducted on the mentioned phenomena. Experimental and numerical studies are both taken into consideration. It proposes some requirements for prospective research in order to fill current gaps in the literature and reveals the upcoming challenges in the design of hydraulic machine

Detection of Divaška Jama corridors behind (to the SW) Trhlovca cave using low frequency high power ground penetrating radar

Ground penetrating radar (GPR) named “Roteg” was used to detect known and unknown passages of Divaška Jama and Trhlovca caves in SW Slovenia. “Roteg’s” main characteristics are an extraordinary high power output (20 MW) and high voltage on antennas (up to 20 kV), which allows penetration more than ten times deeper than common GPRs. During the measurement we used 3-m long antennas (50 MHz) with a central frequency of 50 MHz and we clearly detected the reflections from the depth of 200 m after data processing. During field survey 22 profiles were completed with a total length of 4487.97 m. Pretnerjeva and Žibernova Dvorana chambers in Divaška Jama were well visible on radarograms. New big cavities, which were detected below profiles P18, P21 and P22, are almost all at the same level of 350 – 400 m a.s.l. There is another group of cavities at a level of 420 – 450 m a.s.l., which corresponds to Trhlovca. Both cave groups are separated by the gap which extends in the vertical direction, and probably presents a tectonic zone, which is as well visible on the radarograms. By the use of “Roteg” at the karst surface we were able to detect known caves, new - unknown caves and tectonic zones up to 200 m below the surface.Key words: ground penetrating radar, caves, karst, Divaška Jama, Trhlovca, Slovenia.Določitev rovov Divaške jame v JZ smeri za Trhlovco z uporabo zelo močnega nizkofrekvenčnega georadarjaNizkofrekvenčni georadar (GPR), imenovan »Roteg«, smo uporabili pri zaznavi znanih in neznanih rovov Divaške jame in Trhlovce v JZ Sloveniji. »Rotegove« glavne značilnosti so izjemna moč (20 MW) in visoka napetost do 20 kV na antenah, kar omogoča penetracijo, ki je več kot desetkrat globlja, kot jo dosežejo običajni georadarji. Med meritvami smo uporabili 3 m dolgi anteni (50 MHz) s središčno frekvenco 50 MHz. Tako smo po obdelavi podatkov jasno zaznali odboje iz globine 200 m. Med terenskimi meritvami smo izmerili 22 profilov s skupno dolžino 4490 m. Pretnerjeva in Žibernova dvorana v Divaški jami sta bili dobro vidni na georadarskih profilih. Nove velike jame, ki smo jih zaznali pod profili P18, P21 in P22, so skoraj vse na istem nivoju, 350–400 m nad morjem. Druga skupina jam na nadmorski višini 420–450 m ustreza Trhlovci. Obe skupini jam sta ločeni z vrzeljo v navpični smeri, ki je verjetno tektonska cona in je dobro vidna na georadarskih profilih. Z uporabo »Rotega« na kraškem površju smo določili znane jame, nove neznane jame in tektonske cone do globine 200 m pod površjem.Ključne besede: georadar (GPR), jame, kras, Divaška jama, Trhlovca, Slovenija

energy recovery in oil refineries through the installation of axial pumps as turbines pats in a wastewater sewer a case study

Abstract This paper analyses an energy recovery solution for the application in an oil refinery, which has undergone significant changes in the last decades due to the construction of different plants, services, storage and logistics systems. Nowadays, with the aim to reduce the water contamination close to the refinery, the local regulations imposed to introduce solutions for the treatment of the groundwater underneath the oil treatment plants. In order to reclaim the site and to safeguard the areas close to the oil refinery, an intervention named "Pump & Treat" was adopted by an Italian company which consists in pumping up the underground water and treating it to remove any trace of polluting agent. Subsequently, a part of the treated water is discharged, by gravity, into the sea through a wastewater sewer. An Axial-Flow Pump (AFP) is studied in both pump and turbine modes for being installed in the wastewater sewer of the analysed oil refinery. After evaluating the availability of flow rate and head, the design characteristics of a proper axial turbine were identified. Computational Fluid Dynamics (CFD) simulations of an AFP are performed in both pump and turbine modes. The obtained results were used for scaling down the hydraulic machine and for defining a new one, properly adapted for the wastewater sewer, as energy recovery unit. The selected axial Pump-as-Turbine (PaT) allowed to achieve an economic saving of about 1706 €/year, leading to a Pay-Back Period (PBP) of about 1 year and 10 months

Impact of E-Auctions on Public Procurement Effectiveness

Abstract. Effects of E-Auctions are in expert literature often demonstrated on data from the domain of public procurement. The paper tests for their impact on public procurement effectiveness in conditions of the Czech Republic and within tenders for construction works. Using quantitative methods are analysed also other factors that may influence its strength (openness of the procedures, types of procurement management, etc.)

Numerical and experimental investigation of the cavitating flow within Venturi tube

International audienceHydrodynamic cavitation represents complex physical phenomenon undesirably affecting operation as well as lifespan of many hydraulic machines from small valves to the large hydro power plants. On the other hand, the same phenomenon and its concomitants such as pressure pulsations can be exploited in many positive ways. One of them which seems to be very promising and perspective is the cavitation utilization for reduction of the microorganisms such as cyanobacteria within large bulks of water. Mutual effect of the swirl induced by the upstream mounted generator and flow constriction in converging-diverging nozzle has been experimentally investigated. The main scope of this paper is numerical investigation complementing the experimental results. The multiphase simulations were carried out using the OpenFoam 1606+ and its interPhaseChangeFoam solver. The present study focuses on CFD results of the cavitating velocity field within the nozzle and analysis of the loss coefficient within the nozzle