Raman spectroscopy of amorphous carbon prepared by pulsed arc discharge in various gas mixtures

To meet various application requirements, it is important to enable an improvement of a-C structure and properties, such as hardness, adhesion, and wear resistance. In this study, we used the Raman spectroscopy to investigate the a-C thin films structure dependence on the different deposition parameters. The effect of nitrogen, argon, and hydrogen gas flow rate was analyzed to determine the influence on the film properties. The change in the gas type, combination, and flow had a significant influence on the D and G bands of the a-C Raman spectra. The addition of N2 into the chamber promoted the sp2 creation, while with adding hydrogen the layer contained more sp3 bonds. The depositions of a-C thin films were carried out in pulsed arc discharge vacuum installation. Micro-Raman measurements of the deposited materials were performed using an ISA Dilor-Jobin Yvon-Spex Labram confocal system with 632.8 nm radiation from a He-Ne laser using a back-scattering geometry

Experimental Investigation and Numerical Modelling of Flow Characteristics of Non-Rotating Twin Screw Model

Twin-screw pumps employ clearances between both screws and screw rotors and housing, which cause backflow as function of pressure differential. Reduction of this flow can be reached by proper geometry design. For the experimental investigation, the scaled model 1:2 of the screws section was produced with trapezoidal tooth profile in two modifications differing in tooth width and pitch. Measurement of flow characteristics of non-rotating twin-screw model was carried out for validation and possible corrections of the 3D CFD model. The testing was done with non-Newtonian liquid met in the food industry and additionally also with water. Experimental data were partly compared with results obtained from numerical simulations

Experimental Investigation and Numerical Modelling of Flow Characteristics of Non-Rotating Twin Screw Model

Twin-screw pumps employ clearances between both screws and screw rotors and housing, which cause backflow as function of pressure differential. Reduction of this flow can be reached by proper geometry design. For the experimental investigation, the scaled model 1:2 of the screws section was produced with trapezoidal tooth profile in two modifications differing in tooth width and pitch. Measurement of flow characteristics of non-rotating twin-screw model was carried out for validation and possible corrections of the 3D CFD model. The testing was done with non-Newtonian liquid met in the food industry and additionally also with water. Experimental data were partly compared with results obtained from numerical simulations

Numerical modelling of a non-Newtonian fluid in the twin-screw pump

Twin screw pump is a positive displacement pump, which is widely used in numerous type of foodstuff applications. Numerical CFD analysis presented in this paper focuses on the investigation of the influence of the clearances and the non-Newtonian behaviour of the fluid. The pump operates at low rotational speed and low inlet pressure. As the first step 3D CFD simulation of twin-screw pump non-rotating segment has been carried out using static mesh without rotation. Various empirical equations have been applied to represent the viscosity relations for non-Newtonian fluid in simple shear. The results are compared for two different values of clearances and various approaches to non-Newtonian fluid description. The obtained results showed the effect of both tested parameters. The physical experiment is under preparation to validate the calculation results

D-Rank: a framework for score aggregation in specialized search

In this paper we present an approach to score aggregation for specialized search systems. In our work we focus on document ranking in scientific publication databases. We work with the collection of scientific publications of the CERN Document Server. This paper reports on work in progress and describes rank aggregation framework with score normalization. We present results that we obtained with aggregations based on logistic regression using both ranks and scores. In our experiment we concluded that score-based aggregation favored performance in terms of Average Precision and Mean Reciprocal Rank, while rank-based aggregation favored document discovery

Experimental research of multiphase flow with cavitation in the nozzle

The paper deals with the problems of cavitation in water flow in the nozzle. The area of research is divided into two directions (experimental and numerical research). During the experimental research the equipment with the nozzle is under the measurement and basic physical quantities such as pressure and volume flow rate are recorded. In the following phase measuring of noise which is generated during flow through the nozzle in the area of cavitation is measured at various operating conditions of the pump. In the second part the appropriate multiphase mathematical model including the consideration of cavitation is defined. Boundary conditions for numerical simulation are defined on the basis of experimental measurements. Undissolved air in the flow is taken into account to obtain pressure distribution in accordance to measured one. Results of the numerical simulation are presented by means of basic current quantities such as pressure, velocity and volume fractions of each phase. The conclusions obtained from experimental research of cavitation were applied to modify the multiphase mathematical model

Customer-Oriented Quality of Service Management Method for the Future Intent-Based Networking

The rapid development and spread of communication technologies is now becoming a global information revolution. Customers have a need for communication services, which could be flexibly configured in accordance with their Quality of Experience (QoE) requirements. Realizing the close connection between customer experience and profitability, the service provider has been placing more and more attention on customer experience and QoE. The traditional quality of service management method based on SLA (Service Level Agreement) is not sufficient as a means to provide QoE-related contracts between service providers and customers. The current SLA method is mostly limited and focused on technical aspects of QoS (Quality of Service). Furthermore, they do not follow on the network the principles and semantic approach to the QoS specification for a communication service using QoE parameters. In this paper, we propose a customer-oriented quality of service management method for future IBN (Intent-Based Networking). It is based on a new QoE metric on a scale from 1 to 5, which allows one to take into account the commercial value of e-services for customers. Based on this approach, the network configuration and functionality of network equipment automatically changes depending on customer requirements. To implement the new method of service quality management, an algorithm for routing data packets in the network was developed, taking into account the current load of the forecast path. The algorithm of billing system functioning in conditions of customer-oriented quality management in telecommunication networks has been created. To investigate the effectiveness of the proposed method of service quality management with the traditional SLA method, we developed a simulation network model with the implementation of two approaches. By conducting a simulation, it was determined that the proposed method gives an average gain of 2–5 times for the criterion of the number of customers who require high quality of experience of the service