Loading...

Table of Content

      
    20 October 2021
    Volume 51 Issue 5
    Optimal calculation method of pavement shakedown limit based on genetic algorithm
    Xiuguang SONG,Yingchao ZHANG,Peizhi ZHUANG,He YANG,Haifeng ZHANG,Juan WANG
    Journal of Shandong University(Engineering Science). 2021, 51(5):  1-7.  doi:10.6040/j.issn.1672-3961.0.2021.153
    Abstract ( 155 )   HTML ( 71 )   PDF (4005KB) ( 59 )   Save
    Figures and Tables | References | Related Articles | Metrics

    To solve the problem that road structures are prone to elasto-plastic deformation under the action of long-term reciprocating vehicle loads, based on the static shakedown theorem, the shakedown behavior of the semi-infinite space Mohr-Coulomb structure under the Hertz load was studied, and the genetic algorithm was introduced to construct an efficient calculation method for the lower limit of the shakedown limit of the road structure under the reciprocating vehicle load. The accuracy and efficiency of the new method was verified by comparison with the existing solution method and parameter analysis.

    Modified calculation method of shaft friction for driven pile considering particle size effect
    Peizhi ZHUANG,Yingchao ZHANG,Xiuguang SONG,He YANG,Zhicheng GUO,Yan HU
    Journal of Shandong University(Engineering Science). 2021, 51(5):  8-15.  doi:10.6040/j.issn.1672-3961.0.2021.161
    Abstract ( 102 )   HTML ( 78 )   PDF (7930KB) ( 46 )   Save
    Figures and Tables | References | Related Articles | Metrics

    This study aimed to investigate the influence of particle size on the micropile by conducting theoretical analysis and model tests. The empirical relationship between the critical friction angle and the relative roughness at the pile-soil interface was established, and thus the critical friction angle could be determined quantitively in consideration of the particle size of sands. To emphasis the influence of particle size on the additional normal stress at the soil-pile interface, the shear band at the soil-pile interface was modelled as a hollow cylinder and then a new modified method was proposed based on the elastic cavity expansion theory. Only two new parameters, Poisson's ratio and the thickness of the shear band, were involved in the modified method, which was validated by comparison with model tests. It was found that the pile shaft friction was mainly determined by the pile roughness and the ratio of pile diameter to sand median size and the critical state angle at the pile-soil interface, while the additional normal stress mainly results from the pile roughness and the ratio of pile diameter to sand median size, respectively. The research could provide the valueable reference for the bearing capacity design of micropiles.

    Review on development of simultaneous localization and mapping technology
    Jianqing WU,Xiuguang SONG
    Journal of Shandong University(Engineering Science). 2021, 51(5):  16-31.  doi:10.6040/j.issn.1672-3961.0.2021.168
    Abstract ( 146 )   HTML ( 74 )   PDF (2986KB) ( 43 )   Save
    Figures and Tables | References | Related Articles | Metrics

    As a hot spot in the field of intelligent transportation, simultaneous localization and mapping (SLAM) technology is the key to autonomous path planning for self-driving vehicles. This review focused on four parts with introduction of sensors related to SLAM technology, localization, mapping, and multi-sensor integration. Each step of realization for SLAM technology was introduced from advantages and disadvantages, range of application, probability algorithm, types of map, and integration methods. Based on the investigation of relevant researches about multi-sensor integration, common problems of SLAM technology were analyzed, future development trend and practical engineering application of SLAM technology were prospected.

    Review on structural resistance to downburst wind loads
    TIAN Li,Wenzhe BI,Sarim Saleem SIDDIQUI,Kaiyue LIU
    Journal of Shandong University(Engineering Science). 2021, 51(5):  32-41.  doi:10.6040/j.issn.1672-3961.0.2020.102
    Abstract ( 62 )   HTML ( 6 )   PDF (2558KB) ( 13 )   Save
    Figures and Tables | References | Related Articles | Metrics

    Researches of downburst in the field of structural wind resistance were introduced. Concerning all kinds of building structures related to people's production and life, this paper reviewed the research and the existing problems to date on the structural resistance to downburst from five aspects: the field measurements, the analytical models, the numerical simulation of the downburst, the wind-tunnel test for downburst, and the wind-induced response analysis of structures. Some problems in view of the structural resistance to downburst for further study were proposed.

    Review of frequency dynamic behavior evolution and analysis method requirements of power system
    Hengxu ZHANG,Yongji CAO,Yi ZHANG,Changgang LI,Jiacheng RUAN,VLADIMIR Terzija
    Journal of Shandong University(Engineering Science). 2021, 51(5):  42-52.  doi:10.6040/j.issn.1672-3961.0.2021.174
    Abstract ( 90 )   HTML ( 7 )   PDF (1810KB) ( 26 )   Save
    Figures and Tables | References | Related Articles | Metrics

    The development of renewable energies changed the operation states of power systems, which complicated the frequency dynamics and brought about new challenges to frequency security and stability. The process of frequency dynamic response was introduced, whose quantitative characteristics and analysis methods were reviewed. And the strengths and promising prospects of frequency dynamics analysis method based on artificial intelligence were emphasized. From the viewpoints of the strong variability of renewables energies, the low inertia of nonsynchronous power sources, and the high risk of large power deficits and cascading faults, the changes of the operation states of power systems were analyzed, and the new requirements on frequency analysis and control were discussed. The inertia definition of power systems with the rapid development of renewable energies was revealed, and the virtual inertia control methods were reviewed. The strengths and promising prospects of the coordination control of multi-type virtual inertia were emphasized. The important issues to be focused in the research area of frequency analysis and control were summarized, and the suggestions for further studies were provided.

    Review and prospect of renewable energy ramp events
    Xueshan HAN,Xinyi WANG,Ming YANG,Yixiao YU
    Journal of Shandong University(Engineering Science). 2021, 51(5):  53-62.  doi:10.6040/j.issn.1672-3961.0.2020.287
    Abstract ( 113 )   HTML ( 10 )   PDF (2283KB) ( 28 )   Save
    Figures and Tables | References | Related Articles | Metrics

    This article elaborated the wind and solar power ramp events from the three levels: the definition, prediction method and control strategy. The common definitions of wind and solar ramp were listed, and their advantages and disadvantages were analyzed in turn. It summarized the current mainstream prediction methods of ramp events, which were divided into direct method and indirect method according to whether the power prediction results were used, and the commonly used evaluation indicators were evaluated. It elaborated the current commonly used methods of control strategy, taking energy storage participation as a division, it was divided into finite control strategy without energy storage participation and infinite control strategy with energy storage participation. The current research problems and key research directions in the future were summarized and prospected.

    Research progress of ocean wave energy converters
    Yanjun LIU,Shuang WU,Dengshuai WANG,Ruohong WANG
    Journal of Shandong University(Engineering Science). 2021, 51(5):  63-75.  doi:10.6040/j.issn.1672-3961.0.2021.234
    Abstract ( 87 )   HTML ( 10 )   PDF (13090KB) ( 26 )   Save
    Figures and Tables | References | Related Articles | Metrics

    In order to accurately keeping the developments of ocean wave energy utilization technology, the important research progress of wave energy converters was reviewed. The forms of wave energy converters had not yet converged. According to the classification principle of different energy capture methods, the working principle and the energy conversion system of three main types of devices, namely, oscillating water column, overtopping and oscillating bodies were introduced. The advantages and disadvantages of each type of converter were analyzed. Typical engineering devices were selected for detailed introduction. The engineering devices which had been completed sea trial in China were summarized. It has been found that the oscillation type was the most popular type of converter in China. The research progress related to the performance evaluation of wave energy converters were summarized, but there was no unified evaluation standard yet. The difficulties and the main breakthrough directions of the developments of wave energy converters were discussed from three aspects of high efficiency and stability, reliability and cost, and the construction of diversified integrated platforms.

    Review and prospect of the development of heat exchanger structure
    Wenjing DU,Junzhe ZHAO,Lixin ZHANG,Zhan WANG,Wanxiang JI
    Journal of Shandong University(Engineering Science). 2021, 51(5):  76-83.  doi:10.6040/j.issn.1672-3961.0.2020.423
    Abstract ( 92 )   HTML ( 9 )   PDF (4892KB) ( 27 )   Save
    Figures and Tables | References | Related Articles | Metrics

    The development of heat exchanger for more than 200 years was introduced. The generation and typical applications of heat exchangers with different structures were reviewed. Four heat exchangers with different structures including shell-and-tube heat exchanger, plate heat exchanger, microstructure heat exchanger, and printed circuit heat exchanger were described emphatically, and the development work of related geometric parameter optimization and structure improvement was carried out to realize heat transfer enhancement. The existing problems and limitations in the structure design of the heat exchanger were analyzed, and the specific suggestions and development trends for the structure improvement of the heat exchanger in the future were proposed.

    Influence of concrete aggregate particle size on acoustic emission detection
    Junwei LI,Fei XU,Bing WANG,Yang GAO
    Journal of Shandong University(Engineering Science). 2021, 51(5):  84-90.  doi:10.6040/j.issn.1672-3961.0.2021.016
    Abstract ( 63 )   HTML ( 6 )   PDF (4738KB) ( 23 )   Save
    Figures and Tables | References | Related Articles | Metrics

    The lead breaking test of concrete specimens with different aggregate sizes was carried out by using acoustic emission technology. The influences of different aggregate particle sizes on the positioning accuracy, sound velocity calibration and time parameter setting of acoustic emission detection concrete materials and the selection of the optimal sensor layout were investigated. The results showed that aggregate was one of the main factors affecting the accuracy of acoustic emission detection. When the aggregate particle size increased 5 mm, the sound velocity decreases by 7.5%. When the aggregate particle size increased 5 mm, the rise time decreased about 3.5%, and the maximum rise time is not more than 200 μs. Perform "multi-multi-point" tests could reasonably determine the optimal sensor arrangement and effectively reduce the positioning error, but it couldn't eliminate the error.

    Influence of calcite veins on shale anisotropy at the microscopic scale based on digital images
    Huailei SONG,Zhonghu WU,Liping LI,Yili LOU,Wenjibin SUN,Hao LIU,Yujun ZUO
    Journal of Shandong University(Engineering Science). 2021, 51(5):  91-99, 106.  doi:10.6040/j.issn.1672-3961.0.2020.276
    Abstract ( 68 )   HTML ( 4 )   PDF (10650KB) ( 14 )   Save
    Figures and Tables | References | Related Articles | Metrics

    The Niutitang Formation shale cores were observed by micro-slice observations and core X-ray whole-rock mineral diffraction analysis, and 7 groups of direct tensile numerical tests under different azimuth angles were performed. The test results showed that the calcite veins had a significant effect on the anisotropy of shale tensile strength. When the azimuth angle increased, the tensile strength gradually decreased. The bedding effect coefficient of tensile strength showed a curve-like growth trend with the increase of azimuth angle, which reached the maximum when α=90°, which was 0.127. The failure modes of shale samples at different angles were very complicated, which could be roughly divided into the following three categories: tree root shape (0°, 15°), step shape (30°, 45°, 60°) and river shape (75°, 90°). Fractures preferentially extended along calcite veins, which might inhibit the formation of complex fracture networks in the shale matrix during hydraulic fracturing. There were also significant differences in the release of dissipated energy under the calcite veins at different angles. The release of dissipated energy under the calcite veins at different angles was also significantly different. When α=0°, 15°, 30°, and 45°, the AE energy was small in the early stage, and increased rapidly to the maximum when it approached the peak stress. When α=60°, 75°, 90°, the AE energy was small in the early stage, and began to increase in the middle stage, and it was the largest when it was close to the peak stress. The cumulative AE energy increased roughly exponentially with increasing strain, and the growth process consisted of three stages: flat period, accelerated period and skyrocketing period. The research results had important reference value for the initiation of hydraulic fractures in shale reservoirs, the prediction of expansion, and the enhancement of oil recovery.

    Horizontal bearing capacity of suction bucket foundation under wave dynamic load
    Haotian LUO,Ke WU,Yameng LI,Jiaxiang XU,Zhihao XING
    Journal of Shandong University(Engineering Science). 2021, 51(5):  100-106.  doi:10.6040/j.issn.1672-3961.0.2020.443
    Abstract ( 57 )   HTML ( 5 )   PDF (4920KB) ( 9 )   Save
    Figures and Tables | References | Related Articles | Metrics

    For the horizontal ultimate bearing capacity of the suction bucket foundation under horizontal dynamic loads such as waves and wind, the explicit dynamic method was adopted to establish the mechanical model of the suction bucket foundation under the wave dynamic load. Based on the infinite boundary and Rayleigh damping, the model optimization analysis was carried out, and the comparative study of the ultimate bearing performance of the foundation under static load and dynamic load (action time 0.5, 1, 2, 5 s) under the same horizontal displacement conditions was carried out. The research results showed that the horizontal ultimate bearing capacity curve of the bucket foundation under different dynamic load time decreased with the increase of the loading time compared with the static load, and gradually approached the static load bearing capacity curve. Affected by the damping of the rock and soil media on the seabed, the rotation center of the barrel under the horizontal load moved up to the top of the barrel as the time of the dynamic load decreased.

    Intelligent commutation system of distribution network based on differential evolution algorithm
    Yunlong ZHAO,Renfei CHE,Jiahui CHEN
    Journal of Shandong University(Engineering Science). 2021, 51(5):  107-113, 121.  doi:10.6040/j.issn.1672-3961.0.2020.110
    Abstract ( 53 )   HTML ( 4 )   PDF (1771KB) ( 9 )   Save
    Figures and Tables | References | Related Articles | Metrics

    The application of three-phase intelligent commutation switch was an effective measure to solve the problem of three-phase load imbalance in low-voltage distribution network. Based on the commutation process of the three-phase intelligent commutation switch, an intelligent commutation system of the distribution network was proposed, which took the differential evolution algorithm as the core and the mixed solid-state switch as the foundation. Aiming at the unbalance degree of three-phase current and the action times of commutation switch, differential evolution algorithm was used to optimize the commutation strategy. The optimal commutation strategy was obtained through initialization, mutation, crossover and selection operation, which improved the real-time and accuracy of the system. In this paper, through the combination of magnetic holding relay and IGBT based solid-state switch, a fast switching method using hybrid solid-state switch was proposed, which the commutation switch showed the characteristics of low power consumption and strong current passing ability, and improved the reliability of the system. The feasibility of the algorithm and switch in fast switching and im-proving the power quality of the commutation process was verified by practical test.

    Photovoltaic power prediction method based on NWP irradiance inclination conversion
    Wenling JIANG,Yanqing ZHAO,Bo WANG,Shuanglei FENG,Yan PEI,Fei ZHANG
    Journal of Shandong University(Engineering Science). 2021, 51(5):  114-121.  doi:10.6040/j.issn.1672-3961.0.2020.104
    Abstract ( 71 )   HTML ( 3 )   PDF (2582KB) ( 32 )   Save
    Figures and Tables | References | Related Articles | Metrics

    Short-term photovoltaic (PV) power predictions statistical methods generally used the horizontal irradiance in numerical weather prediction (NWP) directly, but not the inclined irradiance received by tilt PV panels, which led to the calculation results not accurate enough. This paper proposed a new method to convert horizontal irradiance to inclined one. The method distinguished scattering into molecular scattering and Mie scattering with different properties, and then converted them separately. Using the new method, the paper converted NWP horizontal irradiance to inclined one. Based on inclined one, PV power model and prediction were made. The result of an example showed that the new method, whose root mean square error was 10.25% and correlation coefficient was 0.914 0, was more accurate than the traditional method, which used NWP horizontal irradiance directly.

    Analysis of the influence of the underside baffle and deflector of the fume hood on the flow field
    Ruiyi YAN,Zhen DONG,Sen LU,Yanhua LAI,Mingxin LÜ
    Journal of Shandong University(Engineering Science). 2021, 51(5):  122-130.  doi:10.6040/j.issn.1672-3961.0.2021.177
    Abstract ( 66 )   HTML ( 4 )   PDF (19825KB) ( 13 )   Save
    Figures and Tables | References | Related Articles | Metrics

    For the phenomenon of vortex and gas escape in the flow field of the extant fume hood, the computational fluid dynamics method was used for simulation. This research changed the shape parameters of the underside structure of the fume hood window, used circular arc baffles with different radii, elliptical arc baffles with different lengths, and added deflectors with different radii. Then this research studied the influence of structural changes on the flow field in the fume hood by analyzing the size and location of the vortex to obtain the direction of structural optimization. The results showed that when the height of the underside baffle was low and the length was short, there was obvious large vortex in the center position of the fume hood and near the wall. A baffle with a height greater than 50 mm and a length greater than 90 mm could significantly reduce the vortex at the center of the fume hood and at the junction of the baffle and the side wall. Adding a deflector could optimize the flow field and make the center vortex disappear, and the radius of the deflector should not be greater than 70 mm, otherwise obvious vortices would be excited on the outside and end of the baffle, which provides a basis for the rational design of fume hoods.