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Scenarios such as tidal passenger flow, instantaneous large passenger flow, and mixed operation demand an increasing number of autonomous-rail rapid trams (ART) to increase passenger capacity. However, traditional mechanical physical coupling proves too cumbersome for convenient adjustments. This paper proposes a virtual coupling concept and system architecture for autonomous-rail rapid trams as a solution. This study developed a safe braking model and collaborative control model, in addition to establishing a collaborative planning objective function and constraints. Real-time calculations of speeds, accelerations and traction/braking force percentages for the following ART were conducted under the condition of maintaining the minimum safe distance. Simulations and experiments conducted with real trams demonstrated distances between the trams of less than 5 m, arrival time differences of less than 3 s, parking time differences between the leading and following trams of less than 0.5 s, jerks of the following tram not exceeding 0.4 m/ s3, as well as seamless switching between traction and braking during the operation of virtually coupled trams at 45 km/h. These results underscored the effectiveness of the proposed system in facilitating punctual, precise, comfortable and energy-efficient operation of virtually coupled trams. This research lays a solid foundation for potential future applications of virtually coupled ARTs at scale.

To meet the demand for networked operation and accommodate tidal passenger flow resulting from the expanded applications, autonomous-rail rapid trams have significantly increased their transport capacity. However, this increased capacity has also brought pressure to traffic congestion. Aimed to improve the road traffic rate of autonomous-rail rapid transit (ART) and ease traffic congestion, this paper proposes a "virtual coupling" control system that uses a bidirectional information flow topology for autonomous-rail rapid tram, by drawing on concepts from the cooperative adaptive cruise control (CACC) in automobiles and train virtual coupling. A safe braking model of autonomous-rail rapid tram is initiatively used to derive the minimum space headway for operation safety between coupled formations, and the collaborative planning and MPC-based collaborative control algorithms utilizing an optimal control approach are applied to guarantee the safe, punctual, comfortable, and efficient operation of coupled formations. The simulation results demonstrate that the system proposed in this paper can enable autonomous-rail rapid tram to be virtually coupled at space headway less than 10 m within a speed range of 0 to 60 km/h, thus effectually promoting the transport capacity and operational efficiency of ART.

Visual recognition is easily affected by broken ground identification, reflection of strong light and narrow field of view, while GPS (global positioning system) location is susceptible to occlusion and electromagnetic interference. Using any single positioning method will cause the problem of low tracking availability. Therefore, a fault-tolerant control method of combined vision and GPS combined inertial navigation is proposed in this paper. Firstly, lane line recognition is carried out based on image recognition method, geometric relationship parameters between vehicle and road are obtained, and PID controller is designed for steering control. Secondly, layered electronic map is constructed by RTK-GPS (real-time kinematic GPS), smooth reference track is output, and then Stanley controller is designed for steering control. Finally, vision and GPS tracking control are fused. Through real vehicle verification, the results show that the proposed fusion control strategy effectively improves the small radius turning passing rate of autonomous-rail rapid tram, the maximum passing speed can reach 25 km/h, which is increased by 66.7%, the number of one-way takeovers is reduced by 83.8%, the operation time is reduced by 24.4%, and the system availability is effectively improved.

Summary: The development of a series of elite maize hybrids has greatly increased crop yield in the past decades. Parental lines of these hybrids usually come from different heterotic groups and contain many genetic differences. Identifications of important quantitative trait genes in the elite hybrids can extend our understanding of heterosis and also help to guide genetic improvement.Here, we mapped a major quantitative trait locus using a linkage population from an elite maize hybrid Zhengdan958 and identified ZmLNG1 as the causative gene controlling multiple morphologic traits in maize. A 6‐kb deletion in one parental line of the hybrid leads to the fusion of ZmLNG1 with its nearby gene. The fusion event prevents the C‐terminal of ZmLNG1 from interacting with ZmTON1, which resulted in the change of plant architecture.Further experiments demonstrated that ZmLNG1 could act as a mediator to connect ZmTON1 and ZmOFPs, which belong to another type of plant morphological regulatory proteins, thereby affecting the phosphorylation level of ZmOFPs.These results demonstrate the importance of ZmLNG1 in forming the TON1‐TRM‐PP2A complex and provide a model for the regulation of plant organ morphology by TON1‐recruiting motifs (TRMs) and Ovate family proteins (OFPs). [ABSTRACT FROM AUTHOR]

In this paper, the three failure modes of pipes were summarized and the molecular mechanism and fracture mechanics mechanism of slow crack growth were briefly described. The principle and test process of the strain hardening modulus (SH) method were introduced in detail. The paper also reviewed the research progress in the correlation of material microstructures, the domestic and foreign reliability research of SH method for the evaluation of the slow crack growth resistance of pipes, and the application of SH method for the evaluation of the environmental stress cracking resistance of materials. Finally, the applications of SH method for the control of outlook on product quality was discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of event-based disturbance compensation control for discrete-time surface-mounted permanent magnet synchronous motor (SPMSM) subject to both mismatched external disturbances and the limited communication bandwidth. The mismatched external disturbances make it impossible to transform the original model into the multiple-step-ahead predictor model by using the existing predictor technology. To tackle such a challenge, a novel backstepping-based disturbance compensation control framework is firstly proposed for the discrete-time SPMSM with known system dynamics. In the proposed framework, the disturbance observer is designed to compensate for the external disturbances, and the novel variable substitution/decoupling technology is proposed to design the event-based controller for the original controlled system. The proposed controller is composed of the event-based feedback control signal and the feedforward disturbance compensation signal, thereby improving the system disturbance rejection ability and mitigating the communication resource. Subsequently, an event-based adaptive neural control scheme is proposed by combining a modified neural disturbance observer. The proposed scheme ensures that the tracking error converges to a small neighbourhood of the origin, all the signals in the closed-loop system are bounded and meanwhile the communication resources are greatly reduced. The effectiveness of the proposed controller is illustrated through the simulation results. [ABSTRACT FROM AUTHOR]

Understanding how numerous quantitative trait loci (QTL) shape phenotypic variation is an important question in genetics. To address this, we established a permanent population of 18,421 (18K) rice lines with reduced population structure. We generated reference-level genome assemblies of the founders and genotyped all 18K-rice lines through whole-genome sequencing. Through high-resolution mapping, 96 high-quality candidate genes contributing to variation in 16 traits were identified, including OsMADS22 and OsFTL1 verified as causal genes for panicle number and heading date, respectively. We identified epistatic QTL pairs and constructed a genetic interaction network with 19 genes serving as hubs. Overall, 170 masking epistasis pairs were characterized, serving as an important factor contributing to genetic background effects across diverse varieties. The work provides a basis to guide grain yield and quality improvements in rice.