О действии антидифтерийной сыворотки на инфекционные заболевание глаза : (экспериментальное исследование) : диссертация на степень доктора медицины

http://tartu.ester.ee/record=b1976622~S1*es

Tribological and Mechanical Properties of the Nanostructured Superlattice Coatings with Respect to Surface Texture

This research is funded by the Latvian Council of Science, project “Carbon-rich self-healing multifunctional nanostructured smart coatings (NSC) for high-tech applications using high-power confined plasma technology for their deposition”, project No. 2019/1-0385.Ceramic Nanostructured Superlattice Coatings (NSC) have broad applicability to improve the parts’ and assemblies’ tribological and mechanical properties for the needs of the automotive and aerospace industries. Improving the material properties using nanocoatings for such a widely used material as, for example, bearing steel 100Cr6 makes it possible to improve the service life of machine parts. In this paper, the correlation dependence between tribological and mechanical properties of the NSC and its surface texture are considered to determine how much surface texture will affect the tribological performance of the coated workpieces, as well as the measuring and evaluation procedure of the nanocoatings, are presented. Three different NSC described by a general empirical formula {TiMe1Me2-CN/TiAlSi-N}n and based on the modified carbonitride/nitride non-stoichiometric chemical composition were created, and their tribological and mechanical properties measured and analyzed in the context with surface texture. NSC deposited by the advanced PVD (Physical vapor deposition) technique demonstrated significantly higher wear resistance (up to 28 times), reasonably lower friction coefficient (CoF) (up to 4 times), and significantly higher hardness of the coated workpieces (up to 7 times) versus substrate material. A strong correlation between the steady-state dry sliding friction, CoF, and the amplitude and functional surface texture parameters of tribo-track were observed. The first results of the initiated research regarding the correlation analysis of the tribological and mechanical properties, on the one hand, and surface texture, on the other hand, of the NSC are reported here. © 2022 by the authors.Latvian Council of Science project No. 2019/1-0385; Institute of Solid-State Physics, University of Latvia has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase 2 under grant agreement No. 739508, project CAMART2

A Holistic Approach Towards Surface Topography Analyses for Ice Tribology Applications

A surface texture can be subdivided into three categories based on the magnitude of its wavelengths, i.e., macro-geometrical form, waviness, and roughness (from largest to smallest). Together, these components define how a surface will interact with the opposing surface. In most ice tribology studies, <2% of the entire sample surface is topographically analyzed. Although such a small percentage of the entire surface area generally provides statistically relevant information, the missing information about the texture complexity on a larger scale might reduce the possibility of accurately explaining the resulting tribological behavior. The purpose of this study was to review the existing surface measurement methods related to ice tribology and to present a holistic approach towards surface topography measurements for ice tribology applications. With the holistic surface measurement approach, the entire sample surfaces are scanned, and the measured data is analyzed on different magnitude levels. The discussed approach was applied to sandblasted steel samples which were afterward tested on two different ice tribometers. The experimental results showed that additional information about the sample surface topography enabled a better understanding of the ice friction mechanisms and allowed for a more straightforward correlation between the sample surface topography and its ice friction response

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Rakts sniedz pārskatu par OFDM tehnoloģijas pamat principiem

Simulation to Evaluate Performance of Two Layer Vehicular Networks

The article introduces an integrated network and traffic simulation platform called Opnet (Optimized Network Engineering Tool). This platform provides the capabilities of network simulation and network protocol simulation. In this paper, we simulate two layer network models with WiFi and WiMAX scenarios and compared their throughput and load HTTP and FTP protocols. Evaluating the performance of these schemes in various conditions can help researchers discover their performance limitation

Two Layer Model for Performance Evolution of V2I Network

This research presents data evaluating data transfer rate between a remote object and base station in wireless network standard 802.1g/n. Regularity was observed in data transfer rate dependency from the M number of remote objects. All measurements and conclusions were made under circumstances where objects were positioned stationary relative to base station. As the result of the experiment, the mathematical models for two layer wireless networks and closed cyclic wireless networks were selected as ones who are to be used for choosing an optimal method for performance evaluation of a short range communication vehicular network

A Measurement Study of WLAN Link Recovery Using WDS in a Vehicular Environment

A major challenge of Intelligent Transport System (ITS) is the provision of high capacity wireless networking infrastructure to support vehicular communication. In order to understand the basic processes in such networking, in this paper, we provide the measurement results of TCP performance over IEEE802.11n wireless local area network (WLAN). We concentrate our evaluation on multi hop communications in vehicle to infrastructure (V2I) scenario with three wireless access points. The experiment results testify the possibility of using a wireless distribution system (WDS) to connect APs wirelessly extending the transmission range area of network architecture and the connectivity time of the data transmission. Analysing our results was found that handover is one of the main causes reducing the performance of wireless network

Model for Wireless Base Station Goodput Evaluation in Vehicular Communication Systems

In this paper we present the model of wireless base station goodput evaluation. There was used access point model as queuing system with different kind of requests and cycling auto traffic model. Wireless mobile networks have different parameters, such as client stations distance to access point, number of clients in wireless network range, vehicle speed and traffic type. These parameters were analyzed and presented in this paper

Analyses and Evaluation of Wireless Local Area Network in Vehicular Mobility Scenarios

Vehicle-to-infrastructure (V2I) communication based on wireless local area network (WLAN) technology can provide users in-motion to obtain Internet connectivity. In this paper we present an experimental study of IEEE802.11n with diminished settings compared to the legacy system using off-the-shelf devices in V2I small scale scenario. In order to evaluate the V2I the type of communication in the large scale scenario, in this paper we propose an analytic model to characterize the goodput of WLAN-based networks using Markov process