Dual-channel Operation Research Articles

A Branch-and-Price Algorithm for an Integrated Online and Offline Retailing Distribution System with Product Return

This study identifies critical inefficiencies within a dual-channel operation model employed by a fast fashion company, particularly the independent operation of three logistics distribution systems. These systems result in high operational costs and low resource utilization, primarily due to redundant vehicle dispatches to meet the distinct demands of retail store replenishment, online customer orders, and customer return demands, as well as random and scattered return requests leading to vehicle underutilization. To address these challenges, we propose a novel integrated logistics distribution system design and management method tailored for dual-channel sales and distribution businesses. The approach consolidates the three distribution systems into one cohesive framework, thus streamlining the delivery process and reducing vehicle trips by combining retail and customer visits. An optimization algorithm is introduced to factor in inventory and distribution distance, aiming to achieve global optimization in pairing retail store inventory with online customer orders and unifying the distribution of replenishment products, online products, and returned products. The paper contributes to the field by introducing a new variation of the Vehicle Routing Problem (VRP) that arises from an integrated distribution system, combining common VRP issues with more complex challenges. A custom Branch-and-Price (B&P) algorithm is developed to efficiently find optimal routes. Furthermore, we demonstrate the benefits of the integrated system over traditional, segregated systems through real-world data analysis and assess various factors including return rates and inventory conditions. The study also enhances the model by allowing inventory transfers between retail stores, improving inventory distribution balance, and offering solutions for scenarios with critically low inventory levels. Our findings highlight a significant reduction in total operating cost savings of up to 49.9% and vehicle usage when using the integrated distribution system compared to independent two-stage and three-stage systems. The integrated approach enables the utilization of vacant vehicle space and the dynamic selection and combination of tasks, preventing unnecessary mileage and space wastage. Notably, the integration of inventory sharing among retail stores has proven to be a key factor in generating feasible solutions under tight inventory conditions and reducing operational costs and vehicle numbers, with the benefits amplified in large-scale problem instances.

Dynamic pricing and joint carbon reduction strategies at the production and consumption end in a dual-channel fuel vehicle supply chain

This paper investigates carbon reduction in a fuel automotive supply chain. It consists of a manufacturer responsible for carbon reduction and opening an online channel opportunely and a retailer who markets and sells the product through traditional offline channels. Consumers have a preference for low-carbon and low-fuel consumption. It first analyzes decentralized and centralized decision-making under dual channels as a benchmark for comparison. Then, compare the performance of single and dual channels under decentralized decision-making to explore the advantages and conditions of dual channels and link centralized decision-making to reveal the double marginal effect of the supply chain. Finally, it designs a marketing cost-sharing contract to coordinate the behavior of all parties in the supply chain. The results suggest that as long as consumer preference for online channels reaches a certain threshold, dual-channel operation leads to higher double-ended carbon reduction investment, lower prices, and higher total supply chain profits than single-channel, but instead decreases profits for the retailer. Besides, in contrast to decentralized decision-making, marketing cost-sharing contracts can improve profits for all parties in the supply chain, enhance carbon and fuel consumption reduction investment, and partially address the double-marginal effect of the supply chain.

Electromagnetic Performance Analysis of a Multichannel Permanent Magnet Synchronous Generator

In this paper, we present an analysis of the properties of the prototype three-phase Multichannel Permanent Magnet Synchronous Generator (MCPMSG) prototype designed and constructed by the authors. Each channel of the generator has electrically separated windings, which allows us to create an island system of electricity generation. The analyzed MCPMSG is intended for critical applications, and it is designed for four-channel operation. The purpose of this work is to analyze various configurations of the generator channels to improve the redundancy of the electricity generation system. The MCPMSG operation with one or two independent sources of energy consumption in the case of a dual-channel or double dual-channel operation was investigated. For the analyzed cases, the original mathematical models of the three-phase MCPMSG were developed. On the basis of numerical and laboratory tests, the influence of individual configurations on the MCPMSG output parameters was determined. An original method for diagnosing the operation of the MCPMSG channels was developed. Numerical and laboratory tests of the proposed diagnostic method based on a single voltage signal were carried out. As part of the laboratory tests, selected operating states under conditions of full winding symmetry and internal asymmetry were analyzed. The advantage of the proposed diagnostic method is the control of the operating state of the channels both under load and in the de-energized state. The proposed diagnostic method for control of the individual channel requires measurement of only one voltage signal.

Mild Hybridization of Turboprop Engine With High-Power-Density Integrated Electric Drives

This article shares with the aerospace community a case study of turboprop mild hybridization using a recently developed integrated drive system in the University of Nottingham, U.K., within the ACHIEVE project under EU H2020 CleanSky 2 program (project No. 737814). The developed drive system enables the green taxiing of a turboprop aircraft while on the ground with its engine OFF and as an electrical generator when the turboprop is in the air. The entire system is designed to be able to integrate within the power auxiliary gearbox (PAGB) of a turboprop aircraft. Some of the key features of the developed system include a high-speed permanent magnet machine (up to 14200 rpm) with a dual-three-phase design, silicon carbide (SiC)-based high power density (11.8 kW/L for the power converter, and 35.3 kW/L and 7.2 kW/kg for the machine active parts), integrated cooling design for high-temperature operation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;130~^{\circ }\text{C}$ </tex-math></inline-formula> ambient temperature), fault tolerance consideration with dual-channel operation capabilities, and sensorless control for entire operational conditions. This article is giving an overview of the design process of the electrical machine, power converters, and the cooling of the entire drive. The numerical analysis [finite element method (FEM) and computational fluid dynamics (CFD)] and some experimental results are presented to demonstrate the effectiveness and the desired performance of the developed integrated drive system.

A Dual-Channel High-Linearity Filtering-by-Aliasing Receiver Front-End Supporting Carrier Aggregation

A filtering-by-aliasing (FA) receiver front-end based on a slice-based time-varying architecture was described by Bu and Pamarti (2021). Unlike prior FA architectures, it demonstrated, using a 28-nm CMOS prototype IC, a time-invariant input impedance that enables dual-channel operation with high linearity. Up to 50-dB stopband rejection with a transition bandwidth (BW) of only 3.2 times the RF BW, out-of-band IIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> of +35 dBm, blocker 1-dB compression point of +12 dBm, and local oscillator (LO) leakage power better than −81 dBm were achieved, using a 0.9-V supply. This article elaborates on the design of this prototype, presents detailed analyses of the slice-based architecture, and shows how it addresses many of the prior FA receivers’ problems.

Multi-Rate and Multi-Channel Optical Equalizer Based on Photonic Integration

We propose and experimentally demonstrate a photonic integrated circuit (PIC) that operates as an optical equalizer (OE) with multi-rate and multi-channel capability. The OE has the structure of a 3-tap direct form finite impulse response (FIR) filter and is based on the use of micro-ring resonators (MRRs) for the tuning of its delay lines. The PIC is fabricated on TriPleX platform and has 17 reconfigurable elements in total including nine MRRs, five optical couplers and three standalone phase shifters. Using this OE in an on-off keying system with bandwidth limitations we achieve an eye-diagram opening improvement more than 14 dB working with signals at 4.67 and 5.84 Gbaud both in single- and dual-channel operation. Extension to higher modulation formats is direct. Extension to higher symbol rates is also possible via the use of smaller MRRs.

Preferred Service Investment in the Dual-Channel Supply Chain: Leader-Follower Relationships and Product Characteristics

This paper examines the influence that members’ preferred service investments have on their decision-making and profits in a dual-channel supply chain. We discuss changes in the supplier’s and retailer’s decision-making and optimal profits with reference to their different preferred service investment combination modes and their different leader-follower relationships. We also provide classified comparisons of the supplier’s and retailer’s optimal profits by referring to four types of product characteristics combination modes that are assessed across two channels. By providing classifications and comparisons, we put forward operational insights for the supplier and retailer who have direct implications for their optimal decisions and profits, including selling products with higher homogeneity between two channels, choosing the retailer as the leader of the supply chain, and confirming appropriate preference combination mode under a certain product characteristics. We analyze the influences of the preferred service investment levels as well as preference intensities of the supplier and retailer on their strategies and profits in their respective advantaged states and obtain some enlightenment about the cooperation strategies and relationship-building methods of the supplier and retailer in the actual process of their participation in the dual-channel supply chain operation.

The Fault-Tolerant Quad-Channel Brushless Direct Current Motor

In this study, a permanent magnet brushless direct current machine with multi-phase windings is proposed for critical drive systems. We have named the solution, which has four-stator winding, a quad-channel permanent magnet brushless direct current (QCBLDC) motor. The stator windings are supplied by four independent power converters under quad-channel operation (QCO) mode. After a fault in either one, two, or three channels, further operation of the machine can be continued in triple-channel operation (TCO) mode, dual-channel operation (DCO) mode, or single-channel operation (SCO) mode. In this paper, a novel mathematical model is proposed for a QCBLDC machine. This model takes into account the nonlinearity of a magnetic circuit and all of the couplings between the phases within a given channel, as well as between channels. Based on numerical calculations, the static electromagnetic moment and the coupled fluxes were determined for the individual windings of the variants and work modes being analyzed. A normal work condition can be achieved in the QCO or DCO modes. For the DCO mode, an acceptable case uses a balanced magnetic pull (A and C channels supplied). The DCO A and B type work mode is comparable to the DCO A and C mode with regard to its efficiency in processing electrical energy. The vibroacoustic parameters of this mode, however, are much worse. In fault states, TCO, DCO, and SCO work modes are possible. As the number of active channels decreases, the efficiency of energy processing also decreases. In a critical situation, the motor works in overload mode (SCO mode). Laboratory tests conducted for one of the variants demonstrated that the TCO work mode is characterized by worse vibroacoustic parameters than the DCO A and C mode.

Comparative Analysis of Fault-Tolerant Dual-Channel BLDC and SR Motors

This article presents the results of a comparative analysis of two electronically commutated brushless direct current machines intended for fault-tolerant drives. Two machines designed by the authors were compared: a 12/14 dual-channel brushless direct current motor (DCBLDCM) with permanent magnets and a 12/8 dual-channel switched reluctance motor (DCSRM). Information is provided here on the winding configuration, the parameters, and the power converters of both machines. We developed mathematical models of the DCBLDCM and DCSRM which accounted for the nonlinearity of their magnetization characteristics in dual-channel operation (DCO) and single-channel operation (SCO) modes. The static torque characteristics and flux characteristics of both machines were compared for operation in DCO and SCO modes. The waveforms of the current and the electromagnetic torque are presented for DCO and SCO operating conditions. For DCO mode, an analysis of the behavior of both machines under fault conditions (i.e., asymmetrical control, shorted coil, and open phase) was performed. The two designs were compared, and their strengths and weaknesses were indicated.

A high duty-cycle, multi-channel, power amplifier for high-resolution radiofrequency encoded magnetic resonance imaging.

A radiofrequency (RF) power amplifier is an essential component of any magnetic resonance imaging (MRI) system. Unfortunately, no commercial amplifier exists to fulfill the needs of the transmit array spatial encoding (TRASE) MRI technique, requiring high duty cycle, high RF output power and independently controlled multi-channel capability. Thus, an RF amplifier for TRASE MRI is needed. A dual-channel RF power amplifier dedicated for TRASE at 0.22T (9.27MHz) was designed and constructed using commercially available components. The amplifier was tested on the bench and used a 0.22T MRI system with a twisted solenoid and saddle RF coil combination capable of a single-axis TRASE. The amplifier is capable of sequential, dual-channel operation up to 50% duty cycle, 1kW peak output and highly stable 100μs RF pulse trains. High spatial resolution one-dimensional TRASE was obtained with the power amplifier to demonstrate its capability. The constructed amplifier is the first prototype that meets the requirements of TRASE rectifying limitations of duty cycle and timing presented by commercial RF amplifiers. The amplifier makes possible future high resolution in vivo TRASE MRI.

Dual-channel operation in a synchronously pumped optical parametric oscillator for the generation of broadband mid-infrared coherent light sources.

We report, to the best of our knowledge, a novel approach for generating broadband mid-infrared (mid-IR) light by implementing a dual-channel scheme in a synchronously pumped optical parametric oscillator (SPOPO). Two-channel operation was achieved by inserting a prism pair and two reflection mirrors inside an optical parametric oscillator (OPO) cavity. Pumped by a Yb-fiber laser, the OPO generated an idler wave at ∼3150 nm with a -10 dB bandwidth of ∼13.2 THz, which was twice as much as that of the pump source. This scheme represents a promising technical route to transform conventional SPOPOs into a device capable of generating mid-IR light with very broad instantaneous bandwidth.

Modelling and experimental research of fault‐tolerant dual‐channel brushless DC motor

The brushless permanent magnet direct current (DC) machine with dual three-phase windings is proposed for critical drive systems. It is proposed to call such a solution with a dual stator winding as a dual-channel brushless permanent magnet DC motor (DCBLDC). The stator windings are supplied by two independent power converters under dual-channel operation (DCO) mode. After a fault of one channel, a further operation of the machine can be continued in the so-called single-channel operation mode (SCO). In this study, a mathematical model of DCBLDC machine which takes into account non-linearity of a magnetic circuit and all couplings between phases within a given channel as well as between channels is proposed. The results of experimental tests in static and dynamic states for SCO and DCO modes were presented.

On channel interactions in nested Hall thrusters

Nested Hall thrusters use multiple, concentric discharge channels to increase thrust density. They have shown enhanced performance in multi-channel operation relative to the superposition of individual channels. The X2, a two-channel nested Hall thruster, was used to investigate the mechanism behind this improved performance. It is shown that the local pressure near the thruster exit plane is an order of magnitude higher in two-channel operation. This is due to the increased neutral flow inherent to the multi-channel operation. Due to the proximity of the discharge channels in nested Hall thrusters, these local pressure effects are shown to be responsible for the enhanced production of thrust during multi-channel operation via two mechanisms. The first mechanism is the reduction of the divergence angle due to an upstream shift of the acceleration region. The displacement of the acceleration region was detected using laser induced fluorescence measurements of the ion velocity profile. Analysis of the change in beam divergence indicates that, at an operating condition of 150 V and 30 A, this effect increases the thrust by 8.7 ± 1.2 mN. The second mechanism is neutral ingestion from the adjacent channel resulting in a 2.0 + 0/−0.2 mN increase in thrust. Combined, these mechanisms are shown to explain, within uncertainty, the 17 ± 6.2 mN improvement in thrust during dual channel operation of the X2.

Dual-lasing channel quantum cascade laser based on scattering-assisted injection design.

A dual lasing channel Terahertz Quantum Cascade laser (THz QCL) based on GaAs/Al0.17Ga0.83As material system is demonstrated. The device shows the lowest reported threshold current density (550A/cm2 at 50K) of GaAs/AlxGa1-xAs material system based scattering-assisted (SA) structures and operates up to a maximum lasing temperature of 144K. Dual lasing channel operation is investigated theoretically and experimentally. The combination of low frequency emission, dual lasing channel operation, low lasing threshold current density and high temperature performance make such devices ideal candidates for low frequency applications, and initiates the design strategy for achieving high-temperature performance terahertz quantum cascade laser with wide frequency coverage at low frequency.

Continuous Flow 1H and 13C NMR Spectroscopy in Microfluidic Stripline NMR Chips.

Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline’s favorable geometry. In this study we demonstrate the possibility of dual-channel operation of a microfluidic stripline NMR setup showing one- and two-dimensional 1H, 13C and heteronuclear NMR experiments under continuous flow. We performed experiments on ethyl crotonate and menthol, using three different types of NMR chips aiming for straightforward microfluidic connectivity. The detection volumes are approximately 150 and 250 nL, while flow rates ranging from 0.5 μL/min to 15 μL/min have been employed. We show that in continuous flow the pulse delay is determined by the replenishment time of the detector volume, if the sample trajectory in the magnet toward NMR detector is long enough to polarize the spin systems. This can considerably speed up quantitative measurement of samples needing signal averaging. So it can be beneficial to perform continuous flow measurements in this setup for analysis of, e.g., reactive, unstable, or mass-limited compounds.

Comparative Studies on Mutually Coupled Dual-Channel Switched Reluctance Machines With Different Winding Connections

This paper presents comparative studies of magnetic characteristics and dynamic performances for two mutually coupled dual-channel switched reluctance machines (DCSRMs) with the same properties and different winding connections. A 2D/3D finite element method (FEM) is used to analyze the magnetic field distributions and calculate the static inductance and torque characteristics of these two DCSRMs. The different static magnetic characteristics, details of mathematical models and dynamic performances prediction at transient and steady states for these two DCSRMs under single- and dual-channel operation modes are presented and compared. Finally, an experimental setup for two high speed 12/8-pole DCSRMs with different winding connections is built. The experimental results of these two DCSRMs such as phase current, average torque, copper loss, iron loss and efficiency under different operation modes are presented and compared to verify the analytical and simulation results.

Improved decoupled model of mutually coupled dual‐channel SRM with consideration of magnetic saturation in dual‐channel operation

This study proposes an improved decoupled model of mutually coupled dual-channel switched reluctance machine (DCSRM) based on the equivalent inductance and flux linkage characteristics that consider magnetic saturation in dual-channel operation (DCO) mode. A three-dimensional finite-element analysis (FEA) is used to calculate the static phase equivalent inductance of DCSRM for the simultaneous two-phase excitation with consideration of saturation. And an indirect experimental test is performed to measure the equivalent flux linkage under the simultaneous two-phase excitation and compared with the FEA results. In this improved decoupled model, the phase equivalent inductances and flux linkages in each channel are independent to each other and separately expressed as a function of rotor position and their own phase current. The static magnetic characteristics, details of modelling procedure and performances prediction for the DCSRM under DCO mode without and with consideration of saturation are compared. Finally, an experimental set-up for a 12/8 DCSRM drive system based on dSPACE is built and the simulation and experimental results are compared, which verifies high accuracy of this improved modelling method.

Comparative Study on Dual-Channel Switched Reluctance Generator Performances Under Single- and Dual-Channel Operation Modes

The multichannel generator is a kind of special generator, which is developed to enhance power reliability in safety critical applications. This paper compares the dynamic performance computation for a 12/8 dual-channel switched reluctance generator (DCSRG) under single- and dual-channel operation modes. First, the static phase self- and mutual inductances are numerically calculated through finite element analysis (FEA). Based on the magnetic characteristics, the mathematical and simulation models of DCSRG under different operation modes are presented. In the dual-channel model, the effect of mutual coupling between phases of each channel in the DCSRG is considered. By using these proposed dynamic models, the different performances for the DCSRG under single- and dual-channel operation modes, such as generating process under closed-loop control, steady-state performance at different conditions, sudden change in load operation, and the operating status when changing from motoring to generating, are predicted and compared. Finally, a 12/8 DCSRG system is built for experimentation. The simulation and experimental results are also compared in the DCSRG system under different operation modes to verify the proposed modeling and analysis.

Comparison of analytical models for mutually coupled dual-channel SRM under different operation modes

SUMMARY The dual-channel switched reluctance machine (DCSRM) is a kind of special machine, which is developed to enhance reliability in some safety critical applications. When the DCSRM works under dual-channel operation (DCO) mode, the two channels of DCSRM would have strong interactions between each other due to the magnetic mutual coupling for each channel. This paper proposes a fast analytical model considering the mutual coupling for the DCSRM based on the magnetic charactersitics of self- and mutual inductances. The rapid analytical phase current models are deduced in several different inductance regions, and the different analytical phase current and torque models for the DCSRM under single-channel operation (SCO) and DCO modes are also compared. Using this proposed model, the simulation results of steady-state phase current, average torque-speed and average torque-copper loss characteristics are compared with the experimental results at the same conditions in a 12/8 DCSRM systems under the SCO and DCO modes, which verify this proposed modeling and analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Four-Wave-Mixing-Based Dual-Wavelength Conversion in a Semiconductor Optical Amplifier

The simultaneous wavelength conversion of two different formats or bit-rate optical signals, with low input power, is demonstrated in a highly nonlinear semiconductor optical amplifier with a single strong continuous-wave pump. For two amplitude-modulated signals of different bit rates, moderate penalties are obtained, and for the case of mixed amplitude and phase modulation at 10 Gb/s, practically penalty-free operation is achieved. In all cases, small difference (<; 1.1 dB) between single- and dual-channel operation is obtained, allowing asynchronous operation.