Task offloading under deterministic demand for vehicular edge computing

Haotian Li,Xujie Li,Fei Shen Electronics and Telecommunications Research Instit 2023 ETRI Journal Vol.45 No.4

In vehicular edge computing (VEC) networks, the rapid expansion of intelligent transportation and the corresponding enormous numbers of tasks bring stringent requirements on timely task offloading. However, many tasks typically appear within a short period rather than arriving simultaneously, which makes it difficult to realize effective and efficient resource scheduling. In addition, some key information about tasks could be learned due to the regular data collection and uploading processes of sensors, which may contribute to developing effective offloading strategies. Thus, in this paper, we propose a model that considers the deterministic demand of multiple tasks. It is possible to generate effective resource reservations or early preparation decisions in offloading strategies if some feature information of the deterministic demand can be obtained in advance. We formulate our scenario as a 0-1 programming problem to minimize the average delay of tasks and transform it into a convex form. Finally, we proposed an efficient optimal offloading algorithm that uses the interior point method. Simulation results demonstrate that the proposed algorithm has great advantages in optimizing offloading utility.

Segmentation of Slow Slip Events in South Central Alaska Possibly Controlled by a Subducted Oceanic Plateau

Li, Haotian,Wei, Meng,Li, Duo,Liu, Yajing,Kim, YoungHee,Zhou, Shiyong American Geophysical Union 2018 Journal of Geophysical Research: Solid Earth Vol.123 No.1

Experimental study on ultrasonic-assisted grinding of micro-structured surface on silicon carbide using small diameter grinding wheel

Hongbo Li,Tao Chen,Zhenyan Duan,Yiwen Zhang,Haotian Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

As an effective machining method for hard and brittle materials, ultrasonicassisted grinding (UAG) was employed to manufacture microstructures on SiC in this study. The kinematic characteristics of abrasive grains during machining were analyzed first. After that, the influence of machining parameters on the shape accuracy and surface quality was revealed experimentally. The results demonstrate that the feed rate and ultrasonic amplitude have significant effects on machining quality. The introduction of ultrasonic vibration can effectively reduce the grinding force and improve the surface finish quality. For the micro cylinder array, by selecting the ultrasonic amplitude rationally, the peak-to-valley (PV) value and surface roughness can be decreased by 15.8 % and 27.5 %. Furthermore, microcracks, dominated by lateral cracks and fractures were found on the sub-surface. Compared with conventional grinding, UAG can reduce the subsurface damage (SSD) depth and gain a more uniform distribution of damage regions along the machined surface.

Experimental study on a new type of assembly bolted end-plate connection

Shufeng Li,Qingning Li,Haotian Jiang,Hao Zhang,Lei Yan,Weishan Jiang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.4

The bolted end-plate beam-column connections have been widely used in steel structure and composite structure because of its excellent seismic performance. In this paper, the end-plate bolted connection is applied in the concrete structure, A new-type of fabricated beam-column connections with end-plates is presented, and steel plate hoop is used to replace stirrups in the node core area. To study the seismic behavior of the joint, seven specimens are tested by pseudo-static test. The experimental results show that the new type of assembly node has good ductility and energy dissipation capacity. Besides, under the restraint effect of the high-strength stirrup, the width of the web crack is effectively controlled. In addition, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

A High-Throughput Method Based on Microculture Technology for Screening of High-Yield Strains of Tylosin-Producing Streptomyces fradiae

Yao Zhiming,Fan Jingyan,Dai Jun,Yu Chen,Zeng Han,Li Qingzhi,Hu Wei,Yan Chaoyue,Hao Meilin,Li Haotian,Li Shuo,Liu Jie,Huang Qi,Li Lu,Zhou Rui 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.6

Tylosin is a potent veterinary macrolide antibiotic produced by the fermentation of Streptomyces fradiae; however, it is necessary to modify S. fradiae strains to improve tylosin production. In this study, we established a high-throughput, 24-well plate screening method for identifying S. fradiae strains that produce increased yields of tylosin. Additionally, we constructed mutant libraries of S. fradiae via ultraviolet (UV) irradiation and/or sodium nitrite mutagenesis. A primary screening of the libraries in 24-well plates and UV spectrophotometry identified S. fradiae mutants producing increased yields of tylosin. Mutants with tylosin yield 10% higher than the wild-type strain were inoculated into shake flasks, and the tylosin concentrations produced were determined by highperformance liquid chromatography (HPLC). Joint (UV irradiation and sodium nitrite) mutagenesis resulted in higher yields of mutants with enhanced tylosin production. Finally, 10 mutants showing higher tylosin yield were re-screened in shake flasks. The yield of tylosin A by strains UN-C183 (6767.64 ± 82.43 μg/ml) and UN-C137 (6889.72 ± 70.25 μg/ml) was significantly higher than that of the wild-type strain (6617.99 ± 22.67 μg/ml). These mutant strains will form the basis for further strain breeding in tylosin production.

Effects of β Air Cooling and Subsequent Cold Rolling on Microstructure and Hardness of Zr702 Sheet

Haotian Guan,Lingguo Zeng,Zhijun Li,Linjiang Chai,Yufan Zhu,Yueyuan Wang,Qin Huang,Ke Chen,Liang‑yu Chen,Ning Guo 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.2

In this work, a Zr702 sheet was subjected to β air cooling and then rolled to 15% reduction at room temperature, with theirdetailed microstructural characteristics characterized by electron channeling contrast imaging and electron backscatterdiffraction techniques. Results show that after the β air cooling, the prior equiaxed grains in the as-received material arecompletely transformed into Widmanstätten structures featured by coarse plates with typical phase transformation misorientationsbetween them. The subsequent 15% rolling allows both slip and twinning (especially the {10–12} type) to beactivated readily, leading to significant grain refinement and the appearance of misorientation angle peaks around 3°–5° and85°. Analyses on kernel average misorientations reveal that there exist very low residual strains in the β-air-cooled specimenwhile they are markedly increased after the 15% rolling and preferably distributed near low-angle and twin boundaries. Hardnessmeasurements show that the specimen hardness is evidently decreased from ~ 199 to ~ 170 HV after the β air cooling,which can be attributed to grain coarsening and the scattered orientations associated with the slow β → α transformation. For the 15%-rolled specimen, however, effective grain refinement by twinning and denser low-angle boundaries jointly leadto ~ 35% hardness increment to ~ 228 HV.

Study on seismic performance of connection joint between prefabricated prestressed concrete beams and high strength reinforcement-confined concrete columns

Haotian Jiang,Qingning Li,Weishan Jiang,De-Yi Zhang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.2

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and highstrength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-inplace joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and highstrength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.

Research on anti-seismic property of new end plate bolt connections - Wave web girder-column joint

Haotian Jiang,Qingning Li,Lei Yan,Chun Han,Wei Lu,Weishan Jiang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.1

The domestic and foreign scholars conducted many studies on mechanical properties of wave web steel beam and high-strength spiral stirrups confined concrete columns. Based on the previous research work, studies were conducted on the anti-seismic property of the end plate bolt connected wave web steel beam and high-strength spiral stirrups confined concrete column nodes applied with pre-tightening force. Four full-size node test models in two groups were designed for low-cycle repeated loading quasi-static test. Through observation of the stress, distortion, failure process and failure mode of node models, analysis was made on its load-carrying capacity, deformation performance and energy dissipation capacity, and the reliability of the new node was verified. The results showed that: under action of the beam-end stiffener, the plastic hinges on the end of wave web steel beam are displaced outward and played its role of energy dissipation capacity. The study results provided reliable theoretical basis for the engineering application of the new types of nodes.

Influence of synthesis parameters on phase evolution and micromorphology of lanthanum hexaaluminate

Xiaoao Li,Jianjiang Xin,,Chao Chen,Zhiqiang Du,Haotian Wang 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.2

Lanthanum hexaaluminate is a potential candidate for thermal barrier coatings due to its unique lamellar structure andexcellent thermophysical properties. In this work, lanthanum hexaaluminate was prepared by a solid-state reaction synthesisat 1600 oC, and the effects of aluminum source type and molding method on the phase composition and microstructure of thepowder were studied. It can be seen that the synthesis efficiency of alumina as aluminium source is higher than that ofaluminium hydroxide. However, the flake structure is more obvious when aluminium hydroxide is used to synthesizealuminium hydroxide. In addition, the process of compacting green compact can effectively improve the synthesis efficiencyof LaAl11O18, but it will also affect the formation and growth of grains. Consequently, a high yield of LaAl11O18 powder witha particle size of 3 μm and aspect ratio of 9.88 can be obtained by compacting aluminum hydroxide as the aluminum source.

Seismic tests of RC shear walls confined with high-strength rectangular spiral reinforcement

Huajing Zhao,Qingning Li,Can Song,Haotian Jiang,Jun Zhao 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.24 No.1

In order to improve the deformation capacity of the high-strength concrete shear wall, five high-strength concrete shear wall specimens confined with high-strength rectangular spiral reinforcement (HRSR) possessing different parameters, were designed in this paper. One specimen was only adopted high-strength rectangular spiral hoops in embedded columns, the rest of the four specimens were used high-strength rectangular spiral hoops in embedded columns, and high-strength spiral horizontal distribution reinforcement were used in the wall body. Pseudo-static test were carried out on high-strength concrete shear wall specimens confined with HRSR, to study the influence of the factors of longitudinal reinforcement ratio, hoop reinforcement form and the spiral stirrups outer the wall on the failure modes, failure mechanism, ductility, hysteresis characteristics, stiffness degradation and energy dissipation capacity of the shear wall. Results showed that using HRSR as hoops and transverse reinforcements could restrain concrete, slow load carrying capacity degeneration, improve the load carrying capacity and ductility of shear walls; under the vertical force, seismic performance of the RC shear wall with high axial compression ratio can be significantly improved through plastic hinge area or the whole body of the shear wall equipped with outer HRSR.