Design and implementation of compact tri- and quad-band SIW power divider using modified circular complementary split-ring resonators

This paper presents a miniaturized tri- and quad-band power divider (PD)based on substrate integrated waveguide (SIW). By adopting different types of modified circular complementary split-ring resonators on the top surface of SIW, multiple passbands are generated propagating below the SIW cut-off frequency. The working principle is based on evanescent mode propagation that decreases the operating frequency of the PD and helps in the miniaturization of the proposed structure. The operating frequency of the proposed PD can be individually controlled by changing the dimensions of the resonator. To verify the proposed concept, a tri-band and a quad-band PD exhibiting 3 dB equal power division at 2.41/3.46/4.65 GHz and 2.42/3.78/4.74/5.8 GHz are designed using the full-wave simulator, validated through circuit model, fabricated and experimentally verified. The measured results agree well with the simulations. The proposed PDs have good performance in terms of reasonable insertion loss, isolation, minimum amplitude and phase imbalance, smaller footprint, easy fabrication and integration. The size of the fabricated prototype is 18.3 mm × 8.4 mm, which corresponds to 0.205λ g × 0.094λ g , λ g being the guided wavelength at the first operating frequency.

The Role of Adjacency Pairs to Create Politeness Strategies in Students’ Phatic Utterances

Adjacency pair is one of the language features to make utterances more polite as it creates turn-taking, which means that none of the participants dominates. Adjacency pairs also create functions of phatic communication as stated by Padilla Cruz. According to Levinson, there are nine patterns of adjacency pairs, and most could be found in utterances. The data were taken from 24 students’ phatic utterances, and they were chosen because all participants are classmates. COVID-19 pandemic has forced them not to meet each other for almost 2 semesters, yet they show their closeness and solidarity. After all the data were analyzed using the qualitative method, it can be concluded that there are 7 adjacency pairs: Question-Answer, Offer-Accept, Taking leave-Taking leave, Summons-Answer, Request for information-Grant, Request-Apology, and Greeting-Greeting, and most of them have phatic functions of communication. Using adjacency pairs employs politeness strategies and negative and positive politeness strategies from Brown and Levinson. Negative politeness strategies found are Be conventionally indirect, Question, hedge, and Quality-hedges, while positive politeness strategies found are: Offer, promise, Include both S and H in the activity, and Give gifts to H. One of adjacency- pairs and phatic utterances’ functions is to maintain politeness though the students are classmates with close social distance and equal power, they perform politeness strategies to keep their social relations. The appearance of politeness strategies shows that no matter how informal utterances are, closeness and politeness must stay together.Keywords: adjacency-pairs; phatic utterances; politeness; strategies

THE TENSION BETWEEN THE REAL AND THE PAPER DEAL CONCERNING “NO ORAL MODIFICATION” CLAUSES

This article proposes a new model for the regulation of no oral modification (NOM) clauses. First, the article seeks to offer a deeper understanding of the wishes of the parties in contracts from the perspective of parties' autonomy, distinguishing between intentions focused on the legal relationships and those focused on extra-contractual relations. Second, we explain how enforcement of NOM clauses may influence the parties' relations. Third, the article includes an economic analysis clarifying the roles of efficiency and institutional considerations in the NOM phenomenon. Applying the results of our analysis, we propose a comprehensive model for regulating NOM clauses. The key innovation of the model is context-dependent regulation differentiating among sophisticated and equally powerful parties, unsophisticated parties of equal power, and relationships with power disparities. Our model also offers an auxiliary test to help distinguish between parties' legal relationships and their extra-contractual relations.

Identification of the Technical Condition of Induction Motor Groups by the Total Energy Flow

The paper discusses the method of identifying the technical condition of induction motors by classifying the energy data coming from the main common power bus. The work shows the simulation results of induction motor operation. The correlation between occurring defects and current diagrams is presented. The developed simulation model is demonstrated. The general algorithm for conducting experiments is described. Five different experiments to develop an algorithm for the classification are conducted: determination of the motors number in operation with different power; determination of the motors number in operation with equal power; determination of the mode and load of induction electric motor; determination of the fault and its magnitude with regard to operation and load of induction motor; determination of the fault and its magnitude with regard to operation and load of induction motor with regard to non-linear load in the flow. The article also presents an algorithm for preprocessing data to solve the classification problem. In addition, the classification results are shown and recommendations for testing and using the classification algorithm on a real object are made.

Ultrasound in Continuous Tubular Crystallizers: Parameters Affecting the Nucleation Rate

Ultrasound has proven to be an important tool for controlling nucleation in continuous tubular crystallizers. However, insufficient information is available about the parameters controlling the nucleation rate in a continuous ultrasonic process. Previous research has studied parameters related to the nucleation rate, but has not measured the nucleation rate directly or continuously. In this work, the nucleation rate is measured continuously and inline to solve this problem and achieve a better process understanding. The results indicate that the ultrasound-assisted nucleation process is presumably dominated by secondary nucleation. Additionally, the supersaturation, residence time and flow rate have a strong influence on the nucleation rate. On the other hand, the influence of the ultrasonic power is crucial but levels off once a certain amount of power is reached. The static pressure in the system determines the effective ultrasonic power and is therefore also important for the nucleation rate. Finally, maintaining an equal power per unit of volume and an equal residence time by increasing the tubing diameter seems to be a good scale-up method. These results will improve understanding of ultrasonic tubular crystallizers and how to control them.

Development of a Smart Energy Community by Coupling Neighbouring Community Microgrids for Enhanced Power Sharing Using Customised Droop Control

This article aims to develop a smart isolated energy community (EC) by coupling the neighbouring rural community microgrids (CMGs) with enhanced droop control for efficient power sharing. This recommended solution employs a power management (PM) based droop-control to enable independent neighbouring CMGs to share power on an available basis by not constraining CMG inverters to equal power sharing. During the grid-connected mode, the droop control may have different power setpoints of each CMG. However, during the standalone mode of operation, the power setpoint should be defined according to their power rating and availability to maintain the system stability. In this article, a PM strategy is developed to maintain the power setpoints of the autonomous CMGs. An improper selection of power setpoints in autonomous CMG can raise the DC link voltage to an unmanageable value and can cause an inadvertent shutdown of CMG. The suggested PM-based droop control enables the CMG inverter not to restrict the inverter to equal power share but to distribute its active power as available in an asymmetric way, if required. The dynamic performance of the proposed coupled system incorporated with two remote isolated CMGs is investigated in a MATLAB environment. Further, a laboratory prototype of the proposed system has been developed using a LabVIEW-based sbRIO controller to verify the efficacy of the proposed approach.

Optimal interstage liner design: A parametric study

The current trends for next generation turbofan engines are towards shorter nacelles and increased distances between the fan and the outlet guide vanes. This leads to an overall reduction in lined surface areas as well as an increase in the relative importance of the interstage liner, which is the liner placed between the rotor blades and the stator vanes. So far most of the efforts have been on liners for intakes and bypass ducts. The interstage is different in that the liner is subject to a mean flow with a strong swirl component and shear. The focus of this paper is on the effect of swirling flow on optimal liner attenuation in the interstage region. A broadband source downstream at the Outlet Guide Vanes (OGV) consisting of all propagating modes with equal power in each mode is used. Optimum impedance plots are generated for approach and take-off mean flow conditions. The effect of swirl on liner optimum resistance and reactance and optimum insertion loss is observed for a frequency range characteristic of real turbofan engines.