Switched-line network with digital phase shifter

This article studies a six-bit digital phase shifter and its compatible design through different physiognomies. Furthermore, the communication circuits are applied based on modern knowledge by application. The study started with the initial values of 5.625° as the digital phase shifter is programmed discrete and advanced to a 64-step size. Moreover, the properties of bandwidth are computed by 6.44–10.85 GHz. (C-X band) is related to the phase shifter around the frequency, so the full improvement of 66 dB of the phase shifter is 7 dB. Besides, the phase is changing in array antenna and secondhand in optimal Design. Finally, the study discusses dissimilar kinds of digital phase shifters, to study the parameters that affects the design in future cases.

Hydraulic transients for a pipe line network of treated effluent rising main using SAP 2R

Hydraulic transients occur as a direct result of rapid variations of flow field in pressurized systems. The change in velocity from valve closures or pump operations causes pressure surges that are propagated away from the source throughout the pipeline. The associated pressure changes during a transient period are quite large and occur quickly (within a few seconds). It should also be noted that when the maximum pressures exceed the bar ratings (mechanical strength) of the piping material, failure can occur. Similarly, if the minimum pressure drops below the vapour pressure of the fluid, cavitation can occur. The purpose of the present study is to model and simulate the hydraulic transients in a pipeline network system of treated effluent rising main of Mpophomeni sanitation scheme using SAP 2R. A total of five scenarios were simulated using different combinations. The simulation results show that the transient pressures in the pipeline exceeded the bar rating of the pipe where the bursts or cavitation may occur for the simulated scenario, but transient pressures were reduced to a safe limit after providing water hammer protection devices.

Actual-time modeling of a subway vehicle and Optimal driving management with GA and ABC algorithms

The optimization of operations of subway systems has critical importance in terms of energy efficiency and costs. Therefore, driving management of subway vehicles has been gaining more importance day by day. Optimal Driving Management (ODM) is the optimization of the velocity trajectory of a subway vehicle by considering operating conditions and travel time. In this study, the driving of a subway vehicle has been modeled dynamically with all parameters that affect driving. So, a realistic model has been prepared. Then, a new objective function has been proposed to reduce energy consumption by using the subway vehicle’s acceleration and braking forces parameters for ODM. The Artificial Bee Colony algorithm (ABC) and Genetic algorithm (GA) have been used on the prepared model to determine the driving dynamics of the subway vehicle. The performance of the algorithms has been evaluated in the real line network, which has multiple stations with different characteristics. The energy consumption has been reduced by 10.47% in GA and 8.92% in ABC compared to the actual driving values. Moreover, the results of the study has been analyzed in terms of passenger comfort, cost, and emission values.

Avian-power line interactions in the Gobi Desert of Mongolia: are mitigation actions effective?

Background Electrocution and collisions on power lines are among the leading causes of non-natural mortality for birds. Power lines are exponentially increasing, particularly in developing countries, but mitigation strategies to prevent bird mortality are questionable. Mongolia combines a recently increased power line network, an abundant raptor population, a dangerous crossarm configuration and a habitat with no natural perches, producing many bird-power line interactions. Our aim is to assess the bird mortality caused by power lines in the Gobi Desert of Mongolia, to determine the factors increasing the risk of bird electrocution, and to evaluate the effectiveness of used retrofitting measures. Methods In July 2019 we covered 132.9 km of 15 kV power lines checking 1092 poles. We also conducted bird transects to record raptor and corvid richness and abundance, to assess species vulnerability to electrocution. Results We recorded 76 electrocuted birds of 7 species. Electrocution rate was 6.96 birds/100 poles. The most affected species were Common Raven (Corvus corax) and Upland Buzzard (Buteo hemilasius), highlighting the electrocution of 5 endangered Saker Falcons (Falco cherrug). By contrast, we only recorded 8 individuals of 5 species colliding with wires, the most affected being Pallas’s Sandgrouse (Syrrhaptes paradoxus). About 76.1% of sampled poles had some mitigation measure. Of these, 96.6% were brush perch deflectors and 3.4% rotating-mirrors perch deterrents. We found differences in electrocution rates among crossarm configurations, with the strain insulator with one jumper being the most lethal. Additionally, we found no correlation between bird abundance and electrocution rates, suggesting that some species are more sensitive to electrocution. Although no differences in total bird electrocution rates were detected between poles with and without perch deterrents, when bird size is considered, deterrents reduced the mortality rate of small birds, while they were ineffective for medium-sized birds. Conclusions Despite the widespread use of perch deterrents in the Mongolian power line network, there is still an alarming electrocution rate. This strategy is ineffective and some mechanisms, such as brush perch deflectors, may increase the electrocution rate for some medium-sized birds. Finally, we propose strategies to minimize the avian electrocution rate in the Gobi Desert.

Design of a transmission-line metamaterial with a negative index of refraction at S-Band / Concepção de um metamaterial de linha de transmissão com um índice negativo de refracção na banda S

A metamaterial based on a two-dimensional transmission-line network loaded with inductors and capacitors enabling to achieve negative-refractive-index (NRI) is developed. The dispersion characteristics are calculated by their equivalent circuit model and an operating frequency of 2.95 GHz in which there is impedance matching with free space is chosen in the S-Band. This NRI metamaterial supports transverse electric (TE) waves, thus it can be used in applications such as lensing.

High-speed rail network and periodic timetable: a comparative analysis of operational concepts

This paper compares chosen European high-speed railway (HS) networks in terms of their offer of HS passenger service. The criteria chosen for comparison are network topology, degree of service periodicity and degree of coordination between subsequent services. Only services with HS trains are taken into account. As a result, each examined network is classified according to prevailing approach to passenger service – either Line/Service (LS) Approach, where transfer connections are in general not anticipated, or Network (N) approach, with regular (mostly periodic) public transport lines and periodic transfer connections between them.The comparative analysis has shown that geography had crucial impact not only on national (or regional) HS line network, but on the HS operational concept as well.On trunk HS lines, which connect most populated agglomerations in particular country, there is always – at least during peak times – some form of periodic service, despite compulsory seat reservation (except state-owned carriers in Austria and Germany).Half of analyzed networks can be characterized by N approach – at least on trunk HS lines or within central "core" part of HS network.For Czech HS network, authors recommend to define a core network with application of Integrated Periodic Timetable.

An Adaptive Decision Feedback Equalisation For Broadband Powerline Communication System

Power line networks can be used to increase accessibility of broadband communication services in developing countries. Nevertheless, power line networks are affected by stochastic channel alterations triggered by load connection and disconnection, branched line lengths, branches, etc. This impairment affects the implementation of Broadband Power Line Communication (BPLC) system. This paper therefore proposes an Adaptive Decision Feedback Equalisation (ADFE) technique to overcome the stochastic channel changes in powerline communication channels. An appropriate power-line channel model is selected and channel impulse responses are obtained from the selected channel model. The impulse responses are obtained and used for simulation to analysing the the performance of ADFE technique. The ADFE is simulated and then results are analyzed through comparisons with other equalizers in order to examine its performance. Simulation results prove that the adaptive decision feedback equalizer performs better to overcome the effects of stochastic changes in power-line network compared to other techniques.