Pair Of Ports Research Articles

Strongly interacting photonic quantum walk using single atom beamsplitters

Photonics provide an efficient way to implement quantum walks, the quantum analog of classical random walks, which demonstrate rich physics with potential applications. However, most photonic quantum walks do not involve photon interactions, which limits their potential to explore strongly correlated many-body physics of light. We propose a strongly interacting discrete-time photonic quantum walk using a network of single atom beamsplitters. We calculate output statistics of the quantum walk for the case of two photons, which reveals the strongly correlated transport of photons. Particularly, the walk can exhibit either bosonlike or fermionlike statistics which is tunable by postselecting the two-photon detection time interval. Also, the walk can sort different types of two-photon bound states into distinct pairs of output ports under certain conditions. These unique phenomena show that our quantum walk is an intriguing platform to explore strongly correlated quantum many-body states of light. Finally, we propose an experimental realization based on time-multiplexed synthetic dimensions. Published by the American Physical Society 2024

Dual-Polarized Duplex Patch Antenna Based on a Multiport Ring Feeding Structure

This letter presents a dual-polarized duplex patch antenna using a multi-port ring feeding circuit. The ring circuit consists of four input ports and four output ports. When one input port of the ring circuit is excited, the four output ports form two pairs of differential ports accordingly. Firstly, a four-port wideband patch antenna is developed using this ring feeding circuit. The four output ports of the ring circuit are directly connected to four metal strips and then coupled to the patch radiator. Once any one of the four antenna ports is excited, wide operating bandwidth covering the base-station band 1710-2690 MHz can be obtained. Secondly, a dual-polarized duplex patch antenna is realized by connecting the four antenna input ports to two pairs of bandpass filters. For different requirements, the center frequencies of the two duplex operating bands can be tuned to desired ones within 1710-2690 MHz using specified filters. For demonstration, a prototype of the dual-polarized duplex antenna operating at 2.0 GHz and 2.6 GHz is implemented. Better than 26 dB measured isolation between all the four ports is realized.

Ship routing in inland waterway liner transportation with foldable and standard empty containers repositioning

This paper addresses the container ship routing problem in inland waterway liner transportation. Given estimated weekly full container shipping demands between port pairs and the potential empty container demands at each port, our goal is to design the container ship route and determine the amount of foldable and standard empty containers to be shipped between each port pair in the context of navigational restrictions, so as to maximize the profit of the shipping services. To save possible leasing or storage costs of empty containers at various ports and meet navigational restrictions, the release of foldable containers and the repositioning of empty containers were taken into account in the decision. Two mixed integer programming models are established to optimize ship route and shipping strategies under splittable and unsplittable demands. The models are further improved by projecting arc variables for simulating the transportation of empty containers, and the improved model has fewer decision variables and higher computational efficiency. Numerical experiments based on the Yangtze River are conducted to test the applicability of methods. Finally, some reference recommendations are presented.

US LNG Boom Puts Producers on Pace To Lap the Competition

The US is poised to retake the crown from Australia as the world’s top LNG exporter, a title the country held briefly in 2022 before Freeport LNG went offline due to a fire in June 2022. Freeport LNG recently began supplying cargoes again and may be up to full speed during the second half of this year. In 2021, the US was third in exports behind Australia and Qatar, which sold about 10.5 Bcf/D and 10.1 Bcf/D of gas as LNG, respectively. According to the US Energy Information Administration (EIA), the US began exporting LNG in February 2016, and within 7 years developed the world’s largest LNG export capacity with seven LNG export facilities totaling 13.9 Bcf/D of peak production capacity. US LNG exports exceeded pipeline exports of natural gas for the first time on an annual basis in 2021. Monthly LNG exports set new records throughout 2021 and averaged 11.3 Bcf/D during that winter, 2.2 Bcf/D more than the previous winter. In March 2022, US LNG exports reached a new high of 11.9 Bcf/D. US exports will be further bolstered by new projects moving forward. According to the US Energy Department (DOE), there are currently five export terminals that have received regulatory approvals and are under construction with another dozen either expansion or greenfield projects that have received regulatory clearances but have yet to break ground. Analysts at Wood Mackenzie see a massive investment opportunity for this next wave of US LNG terminals and predict three new projects with a total capacity of over 34 mtpa could start up as soon as 2024—New Fortress Energy’s Louisiana FLNG, Venture Global’s Plaquemines LNG Phase 1, and ExxonMobil/QatarEnergy’s Golden Pass LNG. Another dozen or so projects could find their way to first cargoes by 2028. If the majority of these projects proceed to final investment decision (FID), the market could see a $100-billion infusion over the next 5 years, with three quarters of that investment coming in pre-FID projects, according to Wood Mackenzie. Planned liquefaction terminals range from additional trains on existing plants to ground-up projects, which even includes a pair of offshore ports utilizing FLNG vessels. While the outlook for the US LNG export market looks strong, inflationary issues are threatening to take the bloom off the rose. The overall cost of these projects is on the rise. According to Wood Mackenzie, Calcasieu Pass LNG, which had its FID made in mid-2019, was expected to cost around $580 per tonne. By March 2022, that number had risen to more than $650 per tonne. Other projects are also experiencing inflationary pressures on planned capex. Despite this, the competitive nature of takeaway contracts has kept those fees lower, even as the cost of the terminals rise. That combination could start to squeeze developer returns. The war in Ukraine has been a major factor contributing to the appetite for US LNG and thus, a key driver in securing long-term contracts for future deliveries. European countries dependent on Russian natural gas have pulled back and are attempting to rein in their dependence while seeking new supplies. While many of the newest supplies will not be available for a couple of years, European counties are expected to push through a period of higher volatility and pricing until fresh US imports start to arrive.

Environment and shipping drive environmental DNA beta-diversity among commercial ports.

The spread of nonindigenous species by shipping is a large and growing global problem that harms coastal ecosystems and economies and may blur coastal biogeographical patterns. This study coupled eukaryotic environmental DNA (eDNA) metabarcoding with dissimilarity regression to test the hypothesis that ship-borne species spread homogenizes port communities. We first collected and metabarcoded water samples from ports in Europe, Asia, Australia and the Americas. We then calculated community dissimilarities between port pairs and tested for effects of environmental dissimilarity, biogeographical region and four alternative measures of ship-borne species transport risk. We predicted that higher shipping between ports would decrease community dissimilarity, that the effect of shipping would be small compared to that of environment dissimilarity and shared biogeography, and that more complex shipping risk metrics (which account for ballast water and stepping-stone spread) would perform better. Consistent with our hypotheses, community dissimilarities increased significantly with environmental dissimilarity and, to a lesser extent, decreased with ship-borne species transport risks, particularly if the ports had similar environments and stepping-stone risks were considered. Unexpectedly, we found no clear effect of shared biogeography, and that risk metrics incorporating estimates of ballast discharge did not offer more explanatory power than simpler traffic-based risks. Overall, we found that shipping homogenizes eukaryotic communities between ports in predictable ways, which could inform improvements in invasive species policy and management. We demonstrated the usefulness of eDNA metabarcoding and dissimilarity regression for disentangling the drivers of large-scale biodiversity patterns. We conclude by outlining logistical considerations and recommendations for future studies using this approach.

Chiral topological add–drop filter for integrated quantum photonic circuits

The integration of quantum emitters within topological nanophotonic devices enables the control of light–matter interactions at the single photon level. Here, we experimentally realize an integrated topological add–drop filter and observe multiport chiral emission from single photon emitters (quantum dots) embedded within the device. The filter is imprinted within a valley-Hall photonic crystal membrane and comprises a resonator evanescently coupled to a pair of access waveguides. We show that the longitudinal modes of the resonator enable the filter to perform wavelength-selective routing of light, protected by the underlying topology. Furthermore, we demonstrate that for a quantum dot located at a chiral point in the resonator, selective coupling occurs between well-defined spin states and specific pairs of the filter output ports. The combination of multiport routing, allied with the inherent nonreciprocity of the device at the single photon level, presents opportunities for the formation of complex quantum optical devices, such as an on-chip quantum optical circulator.

Configuration design of the emission control areas for coastal ships: A Stackelberg game model

Several countries and regions have announced sulphur emission control areas (SECAs) to regulate sulphur emissions from ships. Incorporating environmental benefits and economic impacts, a bi-level programming model following the Stackelberg game regime is proposed to capture the SECA design problem for a given coastal area, in which the irregular polygon of the SECA is assumed to be a convex hull and described by a system of linear constraints. The government, as the leader, minimizes total sulphur emissions of ships over the entire coastal area with the voyage cost constraint. The ships, as followers, minimize individual voyage costs by jointly choosing the sailing trajectories and speed profile inside and outside the SECA between the associated port pairs with the given geometric configuration of the SECA. We first derive the optimal trajectory and speed profile for each ship, which can be simplified to a shortest path problem. Subsequently, a heuristic algorithm based on the steepest descent method is proposed to obtain the Pareto optimal solution in the sense of simultaneous minimization of total emissions and voyage costs. Finally, two announced SECAs are adopted to illustrate the validity of the proposed model and algorithm.

Ship Trajectory Clustering Based on Trajectory Resampling and Enhanced BIRCH Algorithm

Automatic identification systems (AIS) provides massive ship trajectory data for maritime traffic management, route planning, and other research. In order to explore the valuable ship traffic characteristics contained implicitly in massive AIS data, a ship trajectory clustering method based on ship trajectory resampling and enhanced BIRCH (Balanced Iterative Reducing and Clustering using Hierarchies) algorithm is proposed. The method has been tested using 764,393 AIS trajectory points of 13,845 ships in the waters of the Taiwan Strait of China, and 832 ship trajectories have been generated and clustered to obtain 172 classes of ship trajectory line clusters among 40 port pairs. The experimental results show that the proposed method has exhibited a good clustering effect on ship trajectories. Compared with the existing ship trajectory clustering methods, the proposed method can more efficiently detect and identify differences between trajectories with largely similar spatial distribution characteristics, so as to obtain legitimate clustering results. In addition, this study has constructed the main ship navigation routes between ports based on the extracted ship trajectory line clusters, and the constructed main routes are directional, refined, and rich in content compared with the existing ship routes. This research provides theoretical and technical support for ship route planning and maritime traffic management.

A single‐layer differential‐fed dual‐band filtering antenna for WLAN application

AbstractIn this letter, a single‐layer differential‐fed dual‐band filtering antenna for wireless local area network application is proposed. The proposed antenna consists of a square patch, and two pairs of stepped impedance resonators (SIRs). The lower operating passband is realized by exciting the square patch with a pair of differential ports. Then, a pair of SIRs is connected with the radiating edge of the square patch to introduce another resonance, thus forming the upper passband. And a radiation null is simultaneously produced to enhance the frequency selectivity between the two passbands. Moreover, another pair of SIRs is utilized to connect with the nonradiating edge of the square patch, which generates an additional high‐frequency in‐band resonance and a radiation null to further improve the bandwidth and frequency selectivity of upper passband. The developed prototype was fabricated and measured to verify the design concept. The measured results are in good agreement with the simulated ones, demonstrating that it exhibits −10 dB fractional impedance bandwidths of 3.68% and 7.35%, maximum realized gains at boresight direction of 5.5 and 8.7 dBi, and cross‐polarization levels smaller than −30 dB, in lower and upper passbands, respectively.

A Deployable Wideband Differential-Fed Dual-Polarized Patch Antenna Array

In this paper, a deployable wideband differential-fed dual-polarized high-isolation patch antenna array is proposed. To achieve dual polarization, every element has two pairs of differential ports. Because of the differential design, the couplings from the adjacent ports (the other pair of ports) are canceled and high isolation between the two polarization is achieved. In addition, capacitive feeds are applied to enhance the bandwidth. By integrating with two planar Marchand baluns, the two pairs of the differential ports are excited for dual polarization. Then, the wideband dual-polarization patch antenna element is expanded to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> antenna array for better gain. In order to achieve deployment, we present a novel foldable mechanism suitable for low-frequency patch antenna array, which is different from the conventional design on the flexible printed board. The deployment concept is presented. One prototype is fabricated and measured. Its operating band is from 1.15 GHz to 1.35 GHz. The peak gains of the two polarizations are 14.4 dBi and 14.1 dBi respectively.

Current-Sensorless Control Strategy for the MPPT of a PV Cell: An Energy-Based Approach

A novel energy-based modelling and control strategy is developed and implemented to solve the maximum power point tracking problem when a photovoltaic cell array is connected to consumption loads. A mathematical model that contains key characteristic parameters of an energy converter stage connected to a photovoltaic cell array is proposed and recast using the port-Hamiltonian framework. The system consists of input-output power port pairs and storage and dissipating elements. Then, a current-sensorless control loop for a maximum power point tracking is designed, acting over the energy converter stage and following an interconnection and damping assignment passivity-based strategy. The performance of the proposed strategy is compared to a (classical) sliding mode control law. Our energy-based strategy is implemented in a hardware platform with a sampling rate of 122 Hz, resulting in lower dynamic power consumption compared to other maximum power point tracking control strategies. Numerical simulations and experimental results validate the performance of the proposed energy-based modelling and the novel control law approach.

A Reversible Hydropump–Turbine System

Water-pumped storage systems have become an ideal alternative to regulate the intermittent power delivered by renewable energy sources. For small-scale operations, a type of centrifugal pump coupled to asynchronous machines represents an adequate solution due to their techno-economic feasibility in addition to their ability to operate as reversible systems. This work provides a novel port-Hamiltonian modelling approach to an integrated reversible hydropump–turbine system, that can be switched from motor pump to turbine-generator by employing a conventional hydraulic switch. Our modelling strategy provides a clear physical interpretation of the energy flow from the mechanical to electrical domains. Then, the model was built with multi-domain storing and dissipating elements and the interconnection of well-defined input–output port pairs. The system’s internal energy, i.e., Hamiltonian function, can be exploited for energy-shaping control strategies. The performance of our modelling approach is validated via numerical simulations.

Assessment of the Centrality of the Cruise Ship Navigation Networks in Southern Europe through the Application of Social Network Analysis

The Mediterranean Sea has been consolidated as the second most important destination region in cruise shipping. This paper investigates the dynamics of the contemporary cruise port network in Southern Europe from the perspective of its centrality. To conduct the research, we applied the technique of social network analysis (SNA) to a set of 20 ports. The set of ports forms a network; therefore, we use the SNA to build this network based on nodes (ports) and to analyze the connections between each other. Several network and node metrics are calculated, such as outgoing and incoming centrality degree, betweenness centrality, and hub index. The goals of this research are (1) to explain the dynamics of the cruise port network for contemporary cruise calls in Southern Europe in terms of the centrality of the ports and the connections between ports, and (2) to obtain a series of graphs with the inter-port relationships of the sample of ports analyzed. Important conclusions are revealed: the cruise traffic registered in a port has an impact on several ports in terms of the number of different ports to which it connects and the intensity of the connection between pairs of ports; the role of betweenness centrality is associated with ports of the same destination region and, in some cases, with ports situated in another destination region; and four ports have been identified as hub ports. The results obtained may help itinerary planners identify alternative ports in the configuration of new itineraries to deal with the challenges associated with the COVID-19 pandemic for cruise shipping.

A MIP-based heuristic for a single trade routing and scheduling problem in roll-on roll-off shipping

We study a single trade ship routing and scheduling problem for a roll-on roll-off shipping company. Along the given trade, there is a number of contracts for transportation of cargoes between port pairs. Each contract states a minimum service frequency where the services should be evenly separated in time and possibly transit time requirements. Current planning practice is to visit all ports along the trade every time it is serviced. Here, we aim instead at determining the sailing route and schedule of each voyage along the trade, i.e., which ports to visit when, which contracts to serve, and the sailing speeds, so that all contract requirements are satisfied at minimum cost. To solve this problem, we have developed a three-phase MIP-based heuristic, where each phase consists of solving dedicated a mixed-integer programming (MIP) model. The heuristic constructs solutions by first identifying the most promising candidate routes along the trade. Next, a candidate route is allocated to each available vessel. Finally, the heuristic determines the allocation of cargoes between the vessels, as well as sailing speeds and arrival times. Computational tests show that the heuristic outperforms a commercial MIP-solver and provides high-quality solutions to realistically sized instances in reasonable time.

A Transmission Line Transition to Extend the Transmission-Line-Excited Magnetoelectric Dipole Antenna Array

A differentially driven transmission-line-excited magnetoelectric dipole (ME-dipole) array antenna is designed for fifth-generation (5G) applications. It is derived from our previous work using a single-layered printed circuit board (PCB) with plated-through-hole technology. The proposed antenna is composed of a 2 × 4 ME-dipole array surrounded by a rectangular cavity. A pair of differential ports feed the antenna. Experiments show that the proposed antenna presents an impedance bandwidth of 26.8% from 55.3 to 72.4 GHz, a 3 dB gain bandwidth of 25% from 55.4 to 71.2 GHz, and a peak gain of 15.3 dBi at 62 GHz. Moreover, the proposed antenna retains all the salient features of the ME-dipole in symmetric radiation patterns and low cross-polarization and back radiation levels.

Fault Modeling and Simulation of Engine Driven Pump in Aircraft Hydraulic System

Abstract The structure of engine driven pump in aircraft hydraulic system is complex, its fault forms are diverse, and the fault transmission path is complex and multi factor coupling. In view of the above problems, based on the in-depth analysis of the working principle of the engine driven pump, the engine driven pump model is established, and the leakage fault injection mechanism of the friction pair is added. The relationship between the flow fluctuation characteristics of engine driven pump and the changes of pump spindle speed, swashplate inclination and pump outlet cavity volume are obtained through model simulation analysis. The mechanism of internal leakage fault of plunger pair, port pair and slipper pair are analyzed, the influence of leakage clearance parameters on key performance indexes such as pump pressure and flow are simulated, and the simulation test data of internal leakage fault of pump are obtained. The simulation results show that the inclination angle of swashplate and spindle speed are positively correlated with the output flow of the pump. The increase of pump outlet volume can effectively alleviate the pressure and flow fluctuation behind the pump. In addition, when the radial clearance of the plunger pair of this type of pump exceeds 0.2mm, the pump fault characteristics begin to appear. At the same time, the load change behind the pump will affect the characterization of the fault of internal leakage of the pump.

Differentially Fed Duplex Filtering Dielectric Resonator Antenna With High Isolation and CM Suppression

A differentially fed duplex filtering dielectric resonator antenna (DFDRA) is proposed. This DFDRA combines the functions of the duplexer, the filter and the antenna into one highly integrated multifunctional module. A dual-mode substrate integrated waveguide (SIW) cavity working as the common feeding structure operates at two orthogonal modes at the lower and higher channel and is differentially fed by two pairs of differential input ports. The DRA working as the common radiation element operates at two orthogonal modes at two channels respectively and is excited by two cross slots etched on the top of the SIW cavity. High-isolation between the two channels is realized due to the two pairs of orthogonal operating modes of the DRA and SIW cavity. Measured results show that the balanced DFDRA can operate with differential mode 10dB impedance bandwidth of 2.7% (5.07-5.21 GHz) and 2.6% (5.72–5.87 GHz), the peak realized gains of 4.6-4.9 dBi and 4.8-5.1 dBi for two channels respectively. The isolation between the lower and higher channels is greater than 75dB. Good common mode suppression is realized.

Asynchronous Deterministic Network Based on the DiffServ Architecture

In this study, we propose a scalable framework that guarantees both latency and jitter bounds in large networks, including the Internet. The framework is composed of two parts: a latency-guaranteeing network and a jitter-guaranteeing end system. For latency bounds, we suggest regulators per class per input–output port pair of the DiffServ-type relay nodes. For jitter bounds, based on the guaranteed latency bounds, we suggest time-stamping and buffers at the network egress edge. The framework does not require network-wide time synchronization, frequency synchronization, flow state maintenance, or flow-level queuing/scheduling. Therefore, the complexity does not increase as the number of flows or network size increases. Moreover, the framework is based on the DiffServ architecture; therefore, it requires minimal modification to the current Internet. We demonstrate that the proposed regulators can achieve latency bounds comparable to the IEEE asynchronous traffic shaping technique. We prove that the jitter is bounded even with realistic limitations such as buffers without cut-through capability. We also prove that in the presence of clock drift, the jitter can still be upper bounded with a suggested compensation algorithm. We demonstrate through experiments on simple programmable microcontrollers that the jitter upper bound can be within a few tens of microseconds, even in a realistic situation with store-and-forward buffers, clock drift, and random network delays.

Real-Life Implementation and Evaluation of Coupled Congestion Control for WebRTC Media and Data Flows

WebRTC enables users to simultaneously transfer media (over the Real-Time Transport Protocol (RTP)) and data (over the Stream Control Transmission Protocol (SCTP)) between web browsers, multiplexed onto a single UDP port pair. This design choice of using two different transport protocols, each with their own congestion control mechanism, can lead to competition between the flows, resulting in undesirable spikes in queuing delay and packet loss. In this paper, we investigate solutions to the harmful effects WebRTC flows cause on each other by having the different congestion controllers of the flows collaborate. Using implementations in the Chromium browser, we show that our mechanism can combine a set of heterogeneous congestion control mechanisms, fairly allocate the available bandwidth between the flows, and reduce overall delay and losses.

Integrated polarization-independent optical isolators and circulators on an InP membrane on silicon platform

In photonic integrated circuits (PICs), optical isolators and circulators are essential to prevent lasers from backreflections and to reroute the light flow. In this paper, an integrated polarization-independent device that can be operated as an optical isolator or an optical circulator, based on an InP membrane on silicon platform, is demonstrated. A cerium-doped yttrium iron garnet die is adhesively bonded on a Mach–Zehnder interferometer, in combination with four polarization converters. The device shows maximum optical isolations of 27.0 dB for transverse-electric (TE)-mode input and 34.0 dB for transverse-magnetic TM-mode input. The device also works as a four-port optical circulator. Optical isolations of at least 18.6 dB and 16.4 dB are measured between each circulator port pair for TE- and TM-mode input, respectively. This work could remove the optical interfaces between laser and isolator for robust production. It also provides a step forward toward a multifunctional and high-density PIC.