Search

The High Energy Photon Source (HEPS) is a synchrotron radiation source with an ultrahigh brightness and under construction in China. Its accelerator system is comprised of a 6-GeV storage ring, a full energy booster, a 500-meV Linac and three transport lines. With deepening investigations on the physics designs of the storage ring and the booster, the physics scheme of the Linac has evolved through multiple versions. The final version of the Linac, including the electron gun, bunching system and main accelerator, has been determined. The Linac is an s-band normal conducting electron linear accelerator with a very high bunch charge and a large bunch charge range. Based on simulations, the Linac could provide electron bunches with charge greater than 8.5-nC, meeting the energy spread and emittance requirements. This paper first reviews the evolution and main considerations for different design versions and then describes the physics design and dynamic simulation results of the final scheme in detail.

The High Energy Photon Source is a fourth-generation synchrotron radiation source being built in China. It is comprised of a storage ring, a full energy booster, a 500-MeV Linac and three transport lines. The pulse charge at the exit of the Linac is required to be up to 7 nC. Both single bunch and three bunches in a beam pulse might be needed according to the studies on instabilities of the booster and the beam dynamic of the main Linac. A bunching system consisting of both sub-harmonic and fundamental frequency structures is designed to meet the requirements. To obtain high transmission efficiency and control the emittance growth, multi-objective genetic algorithm is introduced to optimize the electromagnetic parameters of these structures. In this paper, detailed optimization process and the final results are presented. The total transmission efficiency of the bunching system is 97%, and the transmission efficiency of the main bunch is 95%. The normalized RMS emittance of 8.5 nC included beam charge is smaller than 60 mm mrad. The design of the bunching system is presented, and both the pulse charge and the beam emittance well meet the design requirement.

We successfully synthesized a novel core-shell hybrid metal oxide via a simple one-step hydrothermal method without annealing. This composite of Co3O4 particles covered with SnO2–SnO (Co3O4@SnO2–SnO) predicted better performance compared to pure Co3O4, which strongly depends on the synthetic temperature. The Co3O4@SnO2–SnO prepared at a temperature of 250 °C (labeled Co3O4@SnO2–SnO-250) exhibited an outstanding specific capacitance of 325 F g−1 under the current density of 1 A g−1, which was much higher than those of Co3O4 (12.6 F g−1) and other composites. Additionally, the sample also exhibited good cycle stability performance with a retention rate of 100% after 5000 cycles at a current density of 5 A g−1. Through X-ray photoelectron spectroscopy analysis, the presumed mechanism was that Sn-Ox decreases the surface electron densities of Co3O4, which is beneficial to OH− adsorption and specific capacitance improvement, and the synthetic temperature had a strong impact on the microstructure and thus on the surface electron densities. The most. obvious finding to emerge from this study is that the specific capacitance can be improved through adjusting the surface electron densities of transition metal oxides.

Abscisic acid (ABA) is a critical phytohormone that regulates multiple physiological processes including plant growth and stress tolerance. The core ABA signaling pathway has been well established, but genetic variations mediating ABA responses remain largely unknown. In this study, we performed genome-wide association study (GWAS) to identify loci and genes associated with ABA sensitivity (reflected by seed germination inhibition by ABA) in a panel of 425 rice accessions. The seed germination assay revealed that Aus and indica rice had stronger ABA sensitivity than japonica rice. A total of 48 non-redundant association loci were detected in the indica subpopulation and whole population, and 386 genes in these loci were responsive to ABA or abiotic stresses. Eight association loci were overlapped with previously reported loci for yield under drought stress or for drought-indicative image traits. Haplotype analyses of important candidate genes such as OsSAPK6, a key component in the ABA signaling core, were performed to identify key SNPs/InDels that may affect gene functions through promoter activity regulation, amino acid variation, or gene splicing. These results provide insights into the genetic basis of ABA sensitivity related to stress responses.

The 10-MeV Accelerator-Driven Subcritical (ADS) system Injector-I test stand at the Institute of High Energy Physics (IHEP) is a testing facility dedicated to demonstrating the feasibility of the spoke-based superconducting (SC) linear accelerator (linac) for the ADS project in China. The injector adopted a four-vane copper structure radio frequency quadrupole (RFQ) with an output energy of 3.2 MeV and an SC section accommodating 14 $$\beta _{\text{g}}$$ =0.12 single spoke cavities, 14 SC solenoids, and 14 cold beam position monitors (BPMs). A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave (CW) beam were successfully shooting through. The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low $$\beta$$ and medium $$\beta$$ sections. This paper describes the results achieved, the difficulties encountered, and the experiences obtained during commissioning.

The relationship between subjective and objective evaluations on the steering performance of passenger vehicles is investigated to realize the subjective evaluation with objective measurement and to completely replace the objective measurement by subjective evaluation. The subjective evaluation uses steering performance as the study point, and objective evaluation focuses on angle pulse, wheel, snaking, and central tests. The subjective and objective evaluation systems are established, which consist of 7 subjective evaluation indicators (inherent steering characteristics, steering transient response, yawing response, and others) and 17 objective evaluation indicators (formant frequency, average steering angle, yaw velocity gain, et al.). A total of 7 groups of subjective evaluation score and 17 groups of objective evaluation score are obtained by evaluating 4 vehicles. The functional relationship between subjective and objective evaluations is established through regression analysis. Result shows that a 1D binary linear relationship exists between subjective and objective evaluation indicators under a small sample condition. Most of the subjective evaluation indicators have a negative relationship with formant level within the linear function. The formant level is a critical indicator that influences the steering performance of passenger vehicles on the basis of hypothesis testing and dynamic analysis. The lower the formant level is, the higher the subjective evaluation score will be.

Based on linear motor and hydraulic hybrid energy reclaiming suspension, control strategy for multi-mode switched active suspension is designed. By establishing a quarter vehicle suspension system model, a fuzzy sliding mode controller is designed to control the active suspension system, and design active suspension mode switching strategy to select and switch suspension modes of vehicles under different conditions, it improves the performance of active suspension as well as the feed-ability of the suspension. The accuracy of the model and control strategy is verified by simulation, at the same time, a quarter suspension bench is built for test. The test results show the effectiveness of the simulation. The energy-feed test shows that the energy-feed efficiency of the designed energy reclaiming suspension can reach 17.54%.

A 325-MHz continuous-wave (CW) four-vane radiofrequency quadrupole (RFQ) is employed in Injector-I of the China Accelerator-Driven Subcritical System. The radiofrequency tuning and beam commissioning were performed from January 2014 to January 2017. In a cold test, a stability study showed that the design of the segmented resonantly coupling and dipole stabilizer rods can shift the harmful quadrupole and dipole mode from the fundamental mode to above 2.6 MHz. We also found a simplified tuning method for the field unflatness, involving changing the inserted length of a few plug tuners. For achieving CW-beam commissioning, two full-size RFQs were constructed successively. The commissioning results indicate that the beam transmission rate decreased by approximately 3% as the normalized field unflatness decreased by 1%. A 10-MeV CW proton beam with an average beam current of 2.1 mA was achieved at the target of Injector-I, and the output beam energy of the RFQ was 3.18 MeV.

First, the importance of drivers' peripheral risk perception ability to traffic safety is discussed. Second, the detection of peripheral risk perception ability is put forward and its evaluation indexes are established. Third, 1,325 drivers are tested using the peripheral risk perception detector and the tested accident records of drivers in past three years are investigated. Through analysis of the test data, the objective existence of accident--prone drivers is verified, the effectiveness of the peripheral risk perception detector and the rationality of the evaluation indexes are proven, and the threshold of the peripheral risk perception indexes is identified. RESULTS show that drivers' peripheral risk perception has a significant impact on traffic safety, and that the detection of peripheral risk perception ability can identify and screen out accident--prone drivers. Language: en

Accurate reliability prediction is important for assessing product performances and making maintenance plans. This research applies least square support vector machine (LSSVM) in reliability analysis of engine systems. To evaluate the predictive performance of LSSVM, a comparative study is made and the probability distribution of the forecasting outcomes is analyzed. The experiment simulation results show LSSVM can provide accurate predictions.

Aiming at features of strong randomicity, complexity and nonlinearity in highway freight volume, two forecasting models based on support vector machine (SVM) and least squares support vector machine (LSSVM) are proposed. Comparative research and numerical calculation on these two models shows that the forecasting precise based on SVM is better than LSSVM's, and computational speed of the latter is smaller than the first one. The two methods are both high precise forecasting and are satisfied with the engineering requirement. The forecasting model based on LSSVM is efficient for the freight volume forecasting.