Receiver Port Research Articles

Experimental assessment of blowing effect on vehicle performance and aero-acoustics in small-rotor/wing interaction

The tiltrotor design for urban air mobility (UAM) combines vertical take-off and landing (VTOL) capability with fixed-wing efficiency. However, it confronts challenges posed by downward force due to rotor wake effect. Previous research has employed active flow control, such as blowing air, primarily during forward flight using a single air outlet slot. However, the implications for rotor performance and aero-acoustic characteristics have remained unexplored. The experimental approach in this study involves controlled blowing air with moderate momentum in hover mode, concentrating on rotor performance, download force, noise signature, and the influence of port patterns. It is found that the radial port pattern emerges as pivotal for mitigating downward force and augmenting rotor efficiency. The efficacy of noise reduction hinges on both receiver orientation and port pattern selection. This investigation significantly contributes to understanding the role of blowing effect in optimizing tiltrotor designs, particularly in the context of rotor wake-wing interaction.

Terahertz quasi-perfect vortex beams

We have successfully demonstrated the generation of terahertz (THz) quasi-perfect vortex beams (quasi-PVBs) at 0.3 THz. These THz quasi-PVBs can carry not only an individual orbital angular momentum (OAM) mode but also a multiplexed one. The 3D printed spiral axicon and multiplexed spiral axicon were used to generate THz quasi-PVBs carrying individual and multiplexed OAM modes, respectively. The individual and multiplexed OAM modes are verified using a focal hyperbolic lens method and a modified coordinate transformation method, respectively. A THz quasi-PVB with the multiplexing of multiple different OAM modes holds promise for coupling to a receiver port with a fixed annular index profile, thereby increasing the number of communication channels. These works have potential applications in compact terahertz systems, such as mode division multiplexing, which further enhances the system's capacity.

Optical nonreciprocity via transmissive time-modulated metasurfaces

Abstract The frequency mixing property of time-modulated metasurfaces, attributed to the well-known phenomenon of temporal photonic transition, has led to several exotic functionalities in the last lustrum. Based on this concept, we demonstrate the possibility of achieving nonreciprocal responses in the near-infrared regime via combining a time-modulated platform and a static high-Q metasurface. In particular, the temporal metasurface is designed to up-convert the incident tone to the first higher-order harmonic, while the static platform is implemented to establish a filtering behavior with respect to the incident frequency. It is shown that while the receiver port acquires the transmitted signal in the forward direction, the amount of received power becomes negligible under the time-reversal scenario, which indicates the presented configuration exhibits different optical responses from opposite directions. In addition, the role of operating wavelength and the modulation frequency on the power isolation level are investigated, and it is demonstrated that by appropriate selection, the isolation level can reach −30 dB. Since this is the first time a nonreciprocal response is obtained in the near-infrared regime via a pure temporal modulation, we believe the idea of this paper can be of utmost importance in various applications, such as tunable optical isolators.

MODELS AND TOOLS OF THE AUTOMATED SYSTEM FOR COMPUTER NETWORK TRAFFIC INVESTIGATION USING BERKELEY PACKET FILTER

An approach for automating the monitoring and analysis of incoming network traffic in large-scale computer networks is proposed in the paper. The authors suggest using the Linux Berkeley Packet Filter tool to automate traffic analysis in computer networks. The software structure is developed, which includes two main parts: the service machine and the user machine, it is based on the modular principle, which allows for rapid improvement and modernization of the system. The main algorithms for software functionality are built, namely: the algorithm for processing network packets using the Berkeley Packet Filter tool, and the algorithm of the user-space program for loading the Berkeley Packet Filter program to kernel space and setting up communication with it. A study model of program functioning dynamics based on the Petri net theory has been developed. As a result of the application of models based on the Petri net in the software development process, the system works correctly, all states are accessible, and there are no dead ends. A simulation model of the application of the Berkeley Packet Filter tool for the automation of computer network traffic analysis was designed, and the script was created for testing the developed software system. Implemented Python script generates a flow of network packets with random values in the sender IP address, receiver port number, and protocol. These packets, created by the IP address spoofing methodology, later are sent to the service machine's network interface. The developed computer network traffic monitoring software, that uses the Berkeley Packet Filter tool and is implemented in C, C++, and Python programming languages, provides collecting and processing of computer network traffic data. The output of the analysed results is displayed in a user-friendly form. The development and testing of the created software were carried out on the operating system Arch Linux version 5.10.3, which was previously installed on a virtual machine. The results of traffic testing in computer networks in different modes of normal operation and during DDoS attacks are given. In particular, an example of sidebar output with network traffic statistics over a long period, an example of output with network traffic spike parameters, and an example of a warning message, that the sidebar dashboard will show, are presented.

Calibration of Line Impedance Stabilization Networks / Artificial Mains Networks in Accordance with CISPR 16-1-2 Ed 2.1 2017-11

This paper describes a measurement procedure developed by the Standards and Calibration Laboratory (SCL) for measuring the parameters of single phase 50 Ω//(50 μH + 5 Ω) V-network type line impedance stabilization networks (LISN) or artificial mains networks (AMN) specified in the international standard CISPR 16-1-2, which are the impedance at the equipment-under-test (EUT) port, the isolation between the power port and the receiver port, and the voltage division factor between the EUT port and the receiver port. The corresponding measurement models and evaluation of measurement uncertainties are presented. The characterization method of in-house developed adapters for BS1363 type plug and socket is also presented.

25–53 GHz ultra‐wideband high‐isolation passive balanced duplexer on 0.18‐ μ m BiCMOS for 5G applications

A new ultra-wideband millimetre-wave passive balanced duplexer (DUX), employing a lumped-element Wilkinson power divider and grounded-centre-tap transformer, has been developed using 0.18-m BiCMOS process for fifth generation operations at 28, 37, 39 GHz, and beyond. The developed DUX is configured single-ended transmitter (TX) and antenna (ANT) ports and differential receiver (RX) port. It has an inherent matching at TX, RX and ANT ports, high TX–RX isolation, and highly balanced differential RX waveforms, and is ready for direct integration with a differential low-noise amplifier. Analysis has been performed to confirm the DUX's characteristics and assess its performance. Measured isolation from TX to each single-ended RX port is higher than 50 and 40 dB from dc-20 GHz and dc-60 GHz, respectively. Measured insertion loss from TX to antenna is better than 6.3 dB across 13–53 GHz. Measured insertion loss from ANT to differential RX port is lower than 13.8 dB from 25 to 57 GHz with 10.8 dB at 40 GHz. The core chip only occupies 0.3 mm2.

Hierarchical joint remote state preparation in noisy environment

A novel scheme for quantum communication having substantial applications in practical life is designed and analyzed. Specifically, we have proposed a hierarchical counterpart of the joint remote state preparation (JRSP) protocol, where two senders can jointly and remotely prepare a quantum state. One sender has the information regarding amplitude, while the other one has the phase information of a quantum state to be jointly prepared at the receiver's port. However, there exists a hierarchy among the receivers, as far as powers to reconstruct the quantum state is concerned. A 5-qubit cluster state has been used here to perform the task. Further, it is established that the proposed scheme for hierarchical JRSP (HJRSP) is of enormous practical importance in critical situations involving defense and other sectors, where it is essential to ensure that an important decision/order that can severely affect a society or an organization is not taken by a single person, and once the order is issued all the receivers don't possess an equal right to implement it. Further, the effect of different noise models (e.g., amplitude damping (AD), phase damping (PD), collective noise and Pauli noise models) on the HJRSP protocol proposed here is investigated. It is found that in AD and PD noise models a higher power agent can reconstruct the quantum state to be remotely prepared with higher fidelity than that done by the lower power agent(s). In contrast, the opposite may happen in the presence of collective noise models. We have also proposed a scheme for probabilistic HJRSP using a non-maximally entangled 5-qubit cluster state.

Employing Wireless Networks in Enhancing Occupational Safety at the Developing Seaport – Two Proposals

Abstract The paper proposes two Wireless Body Area Network Sensors (WBANSs) scenarios at the logical and simulation levels for improving occupational safety and health conditions at the developing seaport environment. The Port of Bar (Montenegro) is taken as an exemplar. The logical model is based on the actual position of the Port of Bar at the seaport market, its needs and capacities for the information systems innovation through technology transfer and diffusion. The simulation model analyses the channel between the body central unit (BCU) of the worker’s on port wireless body sub-network and the port access point. The quality of the signal transmission at the physical layer has been tested through a source code generated in the Matlab. The code includes the BCU composite signal modulation, transmission, and demodulation, along with a noise and fading effects analysis. The results of the simulation experiments for the different transmission frequencies and distances between transmitter (worker’s BCU) and receiver (port’s access point) by using binary phase-shift keying (BPSK) and quadratic phase-shift keying (QPSK) modulation schemes are presented. Some directions for further investigations in this field are given, as well.

Internet traffic classification based on flows' statistical properties with machine learning

SummaryMachine learning has recently entered the area of network traffic classification as an alternative to the deep packet inspection technique. It provides both unsupervised and supervised learning algorithms that are capable to put aside similar types of traffic or recognize Internet protocols based on some training, pre‐labeled samples. The current work proposes a new approach in the area of network traffic classification using machine learning. First, we extract the unidirectional and bidirectional flows from a traffic capture. A flow is a collection of packets that share sender and receiver IP address and port. Second, we select relevant statistical properties of these flows and use an unsupervised learning mechanism to group flows into clusters based on the similarities. Eventually, we use this classification as training input for a supervised learning engine that will have to properly determine the class of new, unseen traffic flows. Copyright © 2016 John Wiley & Sons, Ltd.

A Self-Adapting Flexible (SELFLEX) Antenna Array for Changing Conformal Surface Applications

A phased-array test platform for studying the self-adapting capabilities of conformal antennas is developed and presented. Specifically, a four-port 2.45-GHz receiver with voltage controlled phase shifters and attenuators is designed along with four individual printed microstrip patch antennas attached to a conformal surface. Each antenna is connected to the corresponding receiver port with a flexible SMA cable. It is shown that with appropriate phase compensation, the distorted radiation pattern of the array can be recovered as the surface of the conformal array changes shape. This pattern recovery information is then used to develop a new self-adapting flexible 1 × 4 microstrip antenna array with an embedded flexible sensor system. In particular, a flexible resistive sensor is used to measure the deformation of the substrate of a conformal antenna array, while a sensor circuit is used to measure the changing resistance. The circuit then uses this information to control the individual voltage of the phase shifters of each radiating element in the array. It is shown that with appropriate phase compensation, the radiation properties of the array can be autonomously recovered as the surface of the flexible array changes shape during normal operation. Throughout this work, measurements are shown to agree with analytical solutions and simulations.

A Study on the Optimal Receiver Impedance for SNR Maximization in Broadband PLC

We consider the design of the front-end receiver for broadband power line communications. We focus on the design of the input impedance that maximizes the signal-to-noise ratio (SNR) at the receiver. We show that the amplitude, rather than the power, of the received signal is important for communication purposes. Furthermore, we show that the receiver impedance impacts the amplitude of the noise term. We focus on the background noise, and we propose a novel description of the noise experienced at the receiver port of a PLC network. We model the noise as the sum of four uncorrelated contributions, that is, the active, resistive, receiver, and coupled noise components. We study the optimal impedance design problem for real in-home grids that we assessed with experimental measurements. We describe the results of the measurement campaign, and we report the statistics of the optimal impedance. Hence, we study the best attainable performance when the optimal receiver impedance is deployed. We focus on the SNR and the maximum achievable rate, and we show that power matching is suboptimal with respect to the proposed impedance design approach.

Timing Recovery for Backplane Ethernet

The dominant solutions for single-chip multi-port backplane Ethernet transceivers utilize a dual-loop design - a combination of a single master phase-locked loop (PLL) and multiple slave delay-locked loops (DLL). Each transmitter or receiver port has its own DLL, which delays or advances a copy of the master clock from the master PLL to generate its own clock signal for synchronization. The DLLs are typically implemented using current-mode logic phase interpolators. This paper presents an alternative solution to this synchronization problem. Instead of moving the sampling phase, timing recovery is done by changing the group delay of the receiver-side forward equalizer by rotating its tap coefficients. The standard least-mean-square algorithm is used for coefficient rotation. This solution is equivalent to a first-order PLL/DLL, which suffers from steady-state timing offset when there is a frequency offset between the transmitter and the receiver. However, the degradation in performance caused by a frequency offset is significantly reduced by using a coefficient-rotation digital-signal processor capable of detecting and reducing the offset. With a practical frequency accuracy specification of plusmn100 ppm, the improved performance can approach that of the PLL/DLL dual-loop solution.

Filter-based NRD-guide duplexer with low loss and high isolation at 60 GHz

A filter-based duplexer has been developed for a wireless broadband asymmetric digital subscriber line by using NRD guide technology. The isolation between the transmitter port and the receiver port is more than 45 dB, and the insertion loss is less than 3 dB in the 60 GHz band.

A Miniaturized Ferrimagnetic High Power Coaxial Duplexer-Limiter

The device to be described in this presentation is a miniaturized high power coaxial component performing within a single package the functions of circulation, power limiting, and preselection. Attention is principally directed to the limiting and preselection functions which are accomplished through the use of a crossed-strip gyromagnetic coupler which differs from those previously reported in that the second-order nonlinear process rather than the first-order process is the basis for its operation. This limiter has been tested independently at power levels as high as 8 kw and found to exhibit a flat leakage output less than 200 mw and a spike leakage energy of about 0.5 erg. The limiter is mechanically tunable over a frequency range greater than 10% in C band. At a fixed setting the 3 db bandwidth is about 20 Mc. The recovery time of the limiter is determined by the kickback of energy from the garnet spin system. Experimental values of this quantity will be presented. The duplexer-limiter package operates at peak powers up to 40 kw into a 2:1 antenna mismatch. Input VSWR at the transmitter port is less than 1.35. Insertion loss from the transmitter port to the antenna port is less than 0.7 db. Low power insertion loss from antenna port through the limiter to the receiver port is 1.0 db.