Branch Line Research Articles

Feeder delivery vehicle scheduling optimization of high-speed railway express based on trunk and branch intermodal transportation

In view of the traditional branch line end express delivery centralized mode cannot adapt to the growing demand of high-speed rail (HSR) express, resulting in poor connection between trunk and branch line, high cost and poor timeliness. In this paper, the problem of scheduling optimization of branch-line flexible distribution vehicles relying on intermodal transportation of trunk and branch lines is proposed. Considering the number of vehicles, vehicle capacity, customer service time window and other constraints, an integer linear programming mathematical model with the minimum total cost of vehicle transportation cost, usage cost and time window penalty cost as the optimization objective is established. A two-level nested heuristic algorithm with two-level coding structure is proposed to solve the problem. Finally, a simulation example is given to verify the effectiveness of the model and the algorithm. The results show that the vehicle scheduling optimization problem studied in this paper can effectively improve the timeliness and accuracy of HSR express delivery, and can significantly reduce the total vehicle delivery cost.

High gain and circularly polarized beam-switching 8 × 8 Vivaldi antenna array for X-band application

AbstractAn 8 × 8 butler Vivaldi beam-steering antenna array is introduced for X-band application. Circularly polarized array is made of eight Vivaldi elements with 1×8 platform and an 8×8 beam feeding network. Vivaldi radiating element is used in array form to enhance impedance bandwidth and overall efficiency such as gain. Using microwave passive components, for instance, 3 dB branch line couplers and crossover help to have orthogonal modes for feeding each of the elements, hence circular polarization property is achieved. Extracted results show that the array has an impedance bandwidth over 7–12.7 GHz (~58%) for VSWR≤2 and an axial-ratio bandwidth of 3.15 GHz that is between 8.15 and 11.3 GHz (~33%). The peak gain of antenna array is 18 dBi at 10 GHz. The proposed beam-steering antenna with compact size and good operation is capable to cover an angle range from −42 to 55 degree in whole operation frequency.

A modified branch line coupler with compact size and ultra wide harmonics suppression band

ABSTRACT In microstrip branch line coupler (BLC) design, there are significant parameters, including size reduction, insertion loss, and harmonic suppression, which affect the performances of the device. In this paper, a modified BLC with compact size, wide harmonics suppression band, and low insertion loss in operating band is designed. In the proposed design, four types of resonators are used together to create proposed BLC with superior performance. The proposed BLC works at 900 MHz with only 0.1 dB insertion loss at pass band. The proposed BLC provides wide harmonics rejection band from 1.8 to 8.1 GHz, which suppresses 2nd to 9th unwanted harmonics. The conventional coupler occupies 0.25 λ × 0.25 λ, which has undesirable size. But, the proposed BLC occupies compact area of only 21.95 mm × 30.55 mm (0.12 λ × 0.09 λ), which shows more than 81% size reduction.

A compact design of a wideband millimeter‐wave Butler matrix using integrated passive device technology

This study presents a compact, wideband, 4 × 4 Butler matrix using a two-metal-layer thin-film process for millimeter (mm)-wave 5G radio applications. Size reduction techniques are thoroughly discussed for size and performance optimization. A size-reduced quadrature coupler is designed with coplanar waveguide based length-reduced branch lines using capacitive loading effect from the ground bridges. A compact crossover is designed for a return loss of 20 dB or more with negligible crosstalk over a wide frequency range. The circuit components are arranged in an optimized space, allowing negligible coupling between nearby elements. The Butler matrix is fabricated on a quartz substrate at the center frequency of 28 GHz. The fractional bandwidth is 15.4% at a 15-dB return loss and insertion loss is measured in the range of 7.8–8.7 dB at the center frequency. The size of the core circuit is 3.375 × 2.100 m m 2 ${\rm{m}}{{\rm{m}}}^{2}$ , which corresponds to 0.469 × 0.292 λ g 2 ${\lambda }_{g}^{2}$ .

A NOVEL COUPLED LINE COUPLER WITH DEFECTIVE GROUND STRUCTURE (DGS)

This paper examines the development of a 10 dB directionally coupled line coupler with defective ground structure (DGS) using HFSS design tool. The coupler operates in the 4 GHz to 6 GHz frequency range with a high directivity of 46 dB. compared to conventional coupled line coupler and S parameters are calculated. Design optimization is performed in HFSS to meet required specifications. Key Words: Branch Line Coupler, DGS, S parameters

Design of a Modified Compact Coupler with Unwanted Harmonics Suppression for L-Band Applications

This paper presents the design, analysis, and fabrication of a new miniaturized microstrip branch line coupler (BLC) with high harmonics suppression. The T-shaped resonators, open stubs cross-shaped resonators and radial stubs are used in the proposed coupler design. The designed BLC operates at 1 GHz frequency, which can suppress up to 5th spurious harmonics with a 20 dB level of attenuation. High miniaturization of about 86% is obtained for the proposed BLC, which is corresponding to the normalized size of 0.009 λg2. The measured values of isolation and return loss are obtained 28 dB and 29 dB, respectively, while the measured insertion loss of better than 0.2 dB is achieved at the operating frequency. Additionally, the operating bandwidth of the designed coupler ranges from 0.905 GHz up to 1.105 GHz, which shows a 200 MHz operating bandwidth or a fractional bandwidth (FBW) of 20%. The presented BLC is fabricated and measured, where the measurements confirm the simulated results. The designed coupler shows desirable performance compared to the recent designed couplers.

Thermal Fatigue of Pressurized Water Reactor Coolant System Loop Drain Lines Due to Outflow Activities

Abstract Thermal cycling induced fatigue is widely recognized as one of the major contributors to the damage of nuclear plant piping systems, especially at locations where turbulent mixing of flows with different temperature occurs. Thermal fatigue caused by swirl penetration interaction with normally stagnant water layers has been identified as a mechanism that can lead to cracking in dead-ended branch lines attached to pressurized water reactor (PWR) primary coolant system. Electric Power Research Institute (EPRI) has developed screening methods, derived from extensive testing and analysis, to determine which lines are potentially affected as well as evaluation methods to perform evaluations of this thermal fatigue mechanism for the U.S. PWR plants. However, recent industry operating experience (OE) indicates that the model used to predict thermal fatigue due to swirl penetration is not fully understood. There are limitations with the EPRI generic evaluation. In addition, cumulative effects from other thermal transients, especially those resulted from outflow activities, may also contribute to the failure of reactor coolant system (RCS) branch lines. In this paper, we report direct OE from one of our PWR units where thermal fatigue cracking is observed at the RCS loop drain line close to the welded region of the elbow. A conservative analytical approach that takes into account the influence of thermal stratification, in accordance with ASME section III class 1 piping stress method, is also proposed to evaluate the severity of fatigue damage to the RCS drain line, as a result of various transients, particularly the transients from outflow activities. Finally, recommendations are made for future operation and inspection based on results of the evaluation.

Floquet analysis of extended Rabi models based on high-frequency expansion

The extended quantum Rabi models make a significant contribution to understanding of the quantum nature of the atom-light interaction. We transform two kinds of extended quantum Rabi model, the anisotropic Rabi model and the asymmetric Rabi model, into the rotating frame and regard them as periodically driven quantum systems. The analytical solutions of the quasienergy spectrum as well as the Floquet modes for both models are constructed by applying the Floquet theory and the high-frequency expansion, which is applied to the nonstroboscopic dynamics of physical observables such as atomic inversion, transverse magnetization, and atom-field correlation. For the anisotropic Rabi model, the quasienergy fits well with the numerical results even when the rotating-wave coupling is in the deep strong-coupling regime $g\ensuremath{\simeq}\ensuremath{\hbar}\ensuremath{\omega}$ if the counter-rotating term is small enough compared to the driving frequency. Avoided level crossing may occur for quasienergy with the same parity when the positive branch spectrum lines for the total excitation number $N$ cross the negative branch lines for $N+2$, while the high-frequency expansion fails to predict this due to the conservation of the total excitation number. Furthermore, we present analytical and numerical studies of the long-time evolution of population and conclude that the analytical method is credible for the population dynamics. For the asymmetric Rabi model, we find that the external bias field which breaks the parity symmetry of the total excitation number tends to cluster the upper and lower branches into two bundles, and the detuning induced gap in the first temporal Brillouin zone shows a quadratic dependence on the bias. Fourier analysis is applied to extract the frequency composition and two-frequency driving behavior is revealed. Varying the bias strength will change the time-averaged value of the oscillation, which shows how the bias competes with the detuning and atom-field coupling in the driving dynamics. Both models prove that treating the Hamiltonian in the rotating frame by Floquet theory gives an alternative tool in the study of interaction between atom and light.

Simulation of the inherent structural irregularities of high-speed railway turnouts based on a virtual track inspection method

Track geometry parameters measured by a track recording car at a turnout are often hard to interpret due to the concomitant geometric complexity, especially for a high-speed railway turnout whose running edge is not interrupted. The virtual track inspection (VTI) method integrated with a multibody system model is proposed to reveal the longitudinal level and alignment of high-speed railway turnouts when the train passes in the main line and in the branch line. Firstly, the principle of inertial measurement and its implementation in MBS are introduced. Then, the VTI method is applied to the vehicle-turnout dynamics using a single-layered co-running track model and validated on tangent and curved tracks in the spatial and wavelength domain. Zero-phase Filters for wavelength ranges 3–25 m and 1–5 m are necessary to eliminate interference from long waves, and to better identify the switch and crossing, respectively. Finally, the effect of different track foundations is studied, including the two-layered co-running track model and the finite element model on the VTI method.

Dual-band reconfigurable EBG loaded circular patch MIMO antenna using defected ground structure (DGS) and PIN diode integrated branch-lines (BLs)

In this work, a reconfigurable dual-band multiple-input–multiple-output (MIMO) antenna (RDMA) for the fifth generation (5G) 3.5 GHz and industrial, scientific and medical (ISM) 5.2 GHz has been reported. The reported antenna uses the partial ground plane defected ground structure (PGP-DGS) technique and the integration of the pin diode integrated branch lines (BLs) to obtain dual-band operation. Also, the intermediate structure, without DGS operates in wideband to narrowband reconfigurable mode. The operating frequency of the antenna can be tuned to other frequencies by changing the DGS and BLs design attributes. A novel mushroom inspired dual-band electronics bandgap structure is developed and characterized using a dispersion diagram. The proposed EBG is then placed between RDMA to obtain isolation better than −25 dB between closely packed (at λ5G/17.14) antenna elements. The proposed antenna has an acceptable realized gain above 2.5 dBi and a stable end-fire radiation pattern with the main lobe at −45∘.

Fine mapping of qDB.A03, a QTL for rapeseed branching, and identification of the candidate gene.

Increasing the yield of rapeseed is required to meet the rapidly expanding demand for both edible vegetable oil and biofuel. Branching, an important determinant of yield potential in rapeseed, is controlled by a series of quantitative trait loci (QTLs). To explore the genetic mechanism regulating the natural variation of branching, a BC1F1 population derived from a cross between dense branching 2 (dense branching line) and L72 (normal branching line) was used to map QTL conferring branching in rapeseed. A major QTL, qDB.A03, for branching-related traits was identified by the BeadChip Array assisted bulked segregation analysis method, which was subsequently validated by the classical QTL mapping approach, and fine mapped to the 256kb region. This interval contains 56 annotated or predicted genes, 8 of which are candidates for controlling the branching trait. Comparative and expression analysis revealed four promising candidate genes for qDB.A03. Fine mapping and identification of the candidate genes for qDB.A03 represents the first step toward unraveling the genetical and molecular mechanisms controlling branching in rapeseed.

A Robust Detection Method for Multilane Lines in Complex Traffic Scenes

The robustness and stability of lane detection is vital for advanced driver assistance vehicle technology and even autonomous driving technology. To meet the challenges of real-time lane detection in complex traffic scenes, a simple but robust multilane detection method is proposed in this paper. The proposed method breaks down the lane detection task into two stages, that is, lane line detection algorithm based on instance segmentation and lane modeling algorithm based on adaptive perspective transform. Firstly, the lane line detection algorithm based on instance segmentation is decomposed into two tasks, and a multitask network based on MobileNet is designed. This algorithm includes two parts: lane line semantic segmentation branch and lane line Id embedding branch. The lane line semantic segmentation branch is mainly used to obtain the segmentation results of lane pixels and reconstruct the lane line binary image. The lane line Id embedding branch mainly determines which pixels belong to the same lane line, thereby classifying different lane lines into different categories and then clustering these different categories. Secondly, the adaptive perspective transformation model is adopted. In this model, the motion information is used to accurately convert the original image into a bird’s-eye view image, and then the least-squares second-order polynomial fitting is performed on the lane line pixels. Finally, experiments on the CULane dataset show that the proposed method achieved similar or better performance compared with several state-of-the-art methods, the F1 score of the proposed method in the normal test set and most challenge test sets is better than other algorithms, which verifies the effectiveness of the proposed method, and then the field experiments results show that the proposed method has good practical application value in various complex traffic scenes.

Design of a miniaturized branch line microstrip coupler with a simple structure using artificial neural network

Abstract In this paper, a compact branch microstrip coupler with the simple structure using T-shaped resonators and open-ended stubs at 1.8 GHz is designed and fabricated. The proposed coupler creates two transmission zeros at 3.4 and 3.87 GHz, with more than 50 dB attenuation level, which resulted in a good harmonic suppression at 2nd harmonic. Artificial neural network (ANN) has been utilized to extract the transfer function of the proposed coupler resonator for the first time, so the values of the transmission zeros can be located in the desired frequency. This technique can also be used for the other electrical devices. The designed device has a small size of 28 mm × 30 mm (0.9 λ × 0.95 λ), which shows more than 35% size reduction compared to the typical branch-line coupler with λ/4 branch lines. The proposed coupler is simulated using Advanced Design System (ADS) software and fabricated on Rogers Duroid 5880 substrate (ε r = 2.2, h = 31 mil). The simulation and measurement results verify the correct performance of the designed coupler.

A quad-band branch line coupler with high frequency ratio

A quad-band branch line coupler with high frequency ratio

A miniature TSV-based branch line coupler using π equivalent circuit model for transmission line

A miniature TSV-based branch line coupler using π equivalent circuit model for transmission line

Compact flexible and reconfigurable antenna using screen‐printed vanadium dioxide switch for wireless local area network and 5G electronic devices

This article proposes an additive manufacturing compact (30 × 36 × 0.125 mm3), flexible, and reconfigurable antenna with the ability to switch between wideband and dual-band for wireless electronic devices used in the fifth generation (5G) systems and wireless local area network (WLAN) systems. The antenna consists of a folded branch line and an inverted L-shape branch as radiator, and a slot on the ground plane. A vanadium dioxide (VO2) switch is screen-printed on the folded branch line to reconfigure the operation frequencies. The antenna is optimized to operate for a wide bandwidth between 2.46 and 4.3 GHz when the VO2 switch is in the “OFF” state. The antenna exhibits dual narrow-bands at frequencies of 2.4 and 5.2 GHz when the VO2 switch is heated up to 85°C or when a DC current of 50 mA is applied. Simulation and measurement show that the performance of the antenna remains relatively stable under different bending conditions in both the “ON” and “OFF” states of the switch. The operating frequencies can be independently controlled, and a guideline is discussed to design the antenna for other frequencies.

Estimation Method of Disconnection Point Using Common Earthing Conductor for Distribution Line with Branch Line

Estimation Method of Disconnection Point Using Common Earthing Conductor for Distribution Line with Branch Line

Aperture coupled modified rectangular dielectric resonator antenna arrays for X-band applications

This paper proposes an aperture coupled 3×3 rectilinear geometry-based periodic modified rectangular dielectric resonator antenna array for X-band applications. In this paper, the complex electromagnetic field problem of RDRA is addressed through a modified rectilinear-shaped DRA. Notches are created on the dielectric resonator to alter the normal components of the electric field pattern instantaneously. It leads to the reduction in the magnitude of reactive current density, resulting in a lessening of the Q-factor and enhancement of the bandwidth. This antenna shows multiband response, resonating at 8.42, 10.08, and 11.60 GHz frequency with a peak gain of 12.94 dBi at 9.75 GHz with consistent gain stability over the entire frequency band of operation. The radiation efficiency is around 96.1% due to low losses. The impedance bandwidths for different bands are 4.51%, 2.77%, and 4.56% at the resonating frequency of 8.42, 10.08, and 11.60 GHz. A comparative analysis of input and output characteristics is carried out between single, double, and nine-cell arrays. The designed antenna is excited by a branch line series-corporate constrained micro-strip feeding network with three apertures. This novel design is suitable for microwave X-band applications.

Case—Integrative Case Study: Louisiana Branch Lines

Case—Integrative Case Study: Louisiana Branch Lines

Case Article—Louisiana Branch Lines

Louisiana Branch Lines is a struggling Southeast U.S. railroad in just four cities and 12 markets. Their marketing, operations, and finance performance is poor and their departments disjointed. In this customizable, nine-part case, instructors can choose to focus on basic problem structuring and descriptive and predictive statistics, optimization model building, simulation of solutions, or the integration of all of the above. It is based on a real-world case.