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Research on UAV access deployment algorithm based on improved virtual force model
Shuchang Zhang,Duanpo Wu,Lurong Jiang,Xinyu Jin,Shuwei Cen 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.8
In this paper, a unmanned aerial vehicle (UAV) access deployment algorithm is proposed, which is based on an improved virtual force model to solve the poor coverage quality of UAVs caused by limited number of UAVs and random mobility of users in the deployment process of UAV base station. First, the UAV-adapted Harris Hawks optimization (U-AHHO) algorithm is proposed to maximize the coverage of users in a given hotspot. Then, a virtual force improvement model based on user perception (UP-VFIM) is constructed to sense the mobile trend of mobile users. Finally, a UAV motion algorithm based on multi-virtual force sharing (U-MVFS) is proposed to improve the ability of UAVs to perceive the moving trend of user equipments (UEs). The UAV independently controls its movement and provides follow-up services for mobile UEs in the hotspot by computing the virtual force it receives over a specific period. Simulation results show that compared with the greedy-grid algorithm with different spacing, the average service rate of UEs of the U-AHHO algorithm is increased by 2.6% to 35.3% on average. Compared with the baseline scheme, using UP-VFIM and U-MVFS algorithms at the same time increases the average of 34.5% to 67.9% and 9.82% to 43.62% under different UE numbers and moving speeds, respectively.
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Xiong Zhang,Shuchang Wang,Hongquan Yang,Yiping Cui 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4
AlxGa1-xN (0.15 ≤ x ≤ 0.87) epilayers were grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD). The lattice deformation, chemical bonding states, and local electronic structure were characterized by a series of techniques, including X-ray diffraction (XRD), Raman scattering, X-ray photoelectron (XPS), and extended Xray absorption fine structure (EXAFS) spectroscopy. The XRD and Raman spectra revealed that substitution of Ga with Al in AlxGa1-xN epilayers induces a significant contraction in the crystal lattice and a slight expansion of internal parameter u. The XPS measurements indicated the absence of remarkable disorder of the chemical bonds in AlGaN with a high Al content. The EXAFS analysis also demonstrated that the Ga-N and Ga-Al bond lengths are independent of the Al content, whereas the Ga-Ga bond length varies with Al content.
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Maternal Separation Induced Visceral Hypersensitivity from Childhood to Adulthood
( Lisha Yi ),( Haiqin Zhang ),( Huihui Sun ),( Lu Zhou ),( Ying Chen ),( Liqian Xuan ),( Yuanxi Jiang ),( Shuchang Xu ) 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2017 Journal of Neurogastroenterology and Motility (JNM Vol.23 No.2
Background/Aims Early adverse life events (EALs) are relevant to irritable bowel syndrome in adulthood. Maternal separation (MS), as one of the EALs, has proved to induce visceral hypersensitivity in adult rats. However, the effect of MS on visceral hypersensitvity from the post-weaning period to adulthood remains unknown. Methods One hundred and ten neonatal Sprague-Dawley rats were randomly divided into 2 groups: rats in the MS group were exposed to 3 hours daily MS on postnatal day (PND) 2-14; the normal control (NC) group remained undisturbed. Visceral sensitivity was determined by measuring the visceromotor response to colorectal distention on PND21, 35, and 56. Anxiety-like behaviors were measured by the open field test. Results Compared with NC rats, MS rats showed significant visceral hypersensitivity from the post-weaning period to adult. The proportion of visceral hypersensitive rats decreased with age from 87.5% to 70.0% in the female MS group and from 90.0% to 66.7% in the male MS group. The relative VMR ratio of MS and NC on PND21 was higher than PND35 and PND56. MS rats showed decreased ability of movement and exploration to the novel environment in the post-weaning period, obesity in the prepubertal period, and more anxietylike behaviors in adulthood. Conclusions MS can significantly affect visceral sensitivity and behaviors of rats in different age stages, especially in the post-weaning period. Visceral hypersensitivity of MS rats is more pronounced in the post-weaning period and slightly restored in adults. Thus, visceral hypersensitivity in the post-weaning period might play a more meaningful pathophysiologic role in the formation of adult irritable bowel syndrome. (J Neurogastroenterol Motil 2017;23:306-315)
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