One-Dimensional Transient Wave Propagation in a Dry Overlying Saturated Ground

Jiang Tao Yi,Lei Zhang,Fei Jian Ye,Siang Huat Goh 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

While the propagation of stress wave generated by dynamic compaction in dry or saturated granular soil has received much coverage in the research literature, attention to situations with dry soil overlying saturated soil, or mixed-phase ground, is limited. In such cases, the compressional waves have to propagate from a dry layer above the groundwater table to saturated soil below the groundwater table. In this paper, the transient wave propagation characteristics in a mixed-phase ground with an idealized interface between the dry and saturated layer is studied. As the time domain solutions for such problems are often unavailable using analytical methods, a numerical approach based on a dual-phase coupled finite element method implemented on a commercial software platform is adopted. The wave behaviour across the interface is studied and the energy transmission and reflection mechanism from dry to saturated layer is examined. The amplitude, speed and attenuation of the compressional waves and their dependencies on the soil permeability, skeleton stiffness and load duration are quantitatively evaluated via a comprehensive parametric study. As a precursor to the numerical investigation of wave propagation in a mixed-phase ground due to dynamic compaction, the results presented in this study are likely to help in providing a better understanding of the ground improvement effect of dynamic compaction in soil involving a groundwater table.

Cotton GhKCH2, a Plant-specific Kinesin, is Low-affinitive and Nucleotide-independent as Binding to Microtubule

( Tao Xu ),( Xue Wei Sun ),( Shi Ling Jiang ),( Dong Tao Ren ),( Guo Qin Liu ) 생화학분자생물학회 2007 BMB Reports Vol.40 No.5

Improvement of wear and tribological performance of Ti-6Al-4V alloy by laser processing of SiC nanoparticle coating

Tao Jiang,Hong Seok Kim 한국생산제조학회 2020 한국생산제조시스템학회 학술발표대회 논문집 Vol.2020 No.10

An investigation of the mechanical property and thermal shock behavior of machinable B₄C/BN ceramic composites

Tao Jiang,Haiyun Jin,Zhihao Jin,Jianfeng Yang,Guanjun Qiao 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1

Machinable B₄C/BN ceramic composites were fabricated by a hot-pressing process at 1,850 ℃ for 1 h under a pressure of 30MPa. In this article, the mechanical property, thermal shock behavior and machinability of the B₄C/BN ceramic composites were investigated. The fracture strength and fracture toughness of B₄C/BN nanocomposites were significantly improved in comparison with B₄C/BN microcomposites. The Vickers hardness of B₄C/BN nanocomposites and B₄C/BN microcomposites decreased gradually with an increase in the content of h-BN, while the machinability of B₄C/BN nanocomposites and B₄C/BN microcomposites were significantly improved. The B₄C/BN ceramic composites with an h-BN content of more than 20 wt% exhibited excellent machinability. The thermal shock resistance of the B₄C/BN ceramic composites was much better than that of the B₄C monolith, and the thermal shock resistance of B₄C/BN nanocomposites was much better than that of B₄C/BN microcomposites. The thermal shock temperature difference (ΔTc) of the B₄C monolith was about 300℃, while the ΔTc of B₄C/BN microcomposites was about 500℃ and the ΔTc of B₄C/BN nanocomposites was about 600℃. Machinable B₄C/BN ceramic composites were fabricated by a hot-pressing process at 1,850 ℃ for 1 h under a pressure of 30MPa. In this article, the mechanical property, thermal shock behavior and machinability of the B₄C/BN ceramic composites were investigated. The fracture strength and fracture toughness of B₄C/BN nanocomposites were significantly improved in comparison with B₄C/BN microcomposites. The Vickers hardness of B₄C/BN nanocomposites and B₄C/BN microcomposites decreased gradually with an increase in the content of h-BN, while the machinability of B₄C/BN nanocomposites and B₄C/BN microcomposites were significantly improved. The B₄C/BN ceramic composites with an h-BN content of more than 20 wt% exhibited excellent machinability. The thermal shock resistance of the B₄C/BN ceramic composites was much better than that of the B₄C monolith, and the thermal shock resistance of B₄C/BN nanocomposites was much better than that of B₄C/BN microcomposites. The thermal shock temperature difference (ΔTc) of the B₄C monolith was about 300℃, while the ΔTc of B₄C/BN microcomposites was about 500℃ and the ΔTc of B₄C/BN nanocomposites was about 600℃.

Finite-time Backstepping for Attitude Tracking with Disturbances and Input Constraints

Tao Jiang,Fubiao Zhang,Defu Lin 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.6

Backstepping (BS) is an important framework to stabilize the high-order nonlinear system. This work develops a finite-time convergence property for the BS framework combined with an auxiliary input saturation compensator and applies it to address attitude tracking problem of a rigid body subjected to disturbances and input constraints. The finite-time convergence of the tracking error is guaranteed by introducing the fractional power of tracing errors. Meanwhile, the finite-time filters of the target commands and the finite-time disturbance observers inspired by multivariable super-twisting algorithm are employed to construct the finite-time BS framework. Another novelty is to propose a novel auxiliary system to handle the adverse effect of input saturation. The singularity of auxiliary dynamics is avoided by the cubic representation of auxiliary variables. Attitude tracking errors are demonstrated to converge to zeros in finite time despite the presence of input saturation and disturbances through Lyapunov theory. Comparative simulations are conducted to demonstrate the effectiveness and superiority of the proposed control system.

Integral Sliding Mode based Control for Quadrotors with Disturbances: Simulations and Experiments

Tao Jiang,Tao Song,Defu Lin 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.8

This work proposes a compound control which combines backstepping control and integral sliding mode (ISM) idea. The backstepping framework is adopted to guarantee nominal performance of the closed-loop system, while the use of ISM is to eliminate the adverse effect of perturbations such that nominal performance is recovered. To avoid the chattering problem of ISM control, novel multivariable super-twisting algorithm is introduced to attenuate this phenomenon. Furthermore, the proposed control law is applied to tackle trajectory tracking problem of quadrotors subjected to parameter uncertainties and external perturbations. To avoid the singularity of rotation dynamics, quaternion-based control is applied in attitude controller design. A rigorous proof for stability of the closed-loop system is derived by the Lyapunov theory. Finally, several comparative simulations and experimental results demonstrate the effectiveness and superiority of the proposed method.

Ambivalence of Family and Disunity of Virtues in Mencius’ Political Philosophy

( Tao Jiang ) 성균관대학교 유교문화연구소 2020 儒敎文化硏究(中文版) Vol.0 No.33

This essay argues that although family plays an important role in Mencius’ moral philosophy, its place in his political philosophy and the relationship between the familial and the political are much more complicated and ambiguous than commonly assumed. We examine two related assumptions about Mencius’ philosophy, one concerning the role of family and the other the unity of virtues, by revisiting the “two-sources” (or “two-roots”) problem identified by David Nivison, offering a different interpretation and reaching a different conclusion. We argue that there are indeed two roots in Mencius’ philosophy, the family root and the general sympathy root. These two are sometimes in conflict within his framework, exposing a deep tension therein. To make the case, we distinguish two distinct strands in Mencius’ thought, the “extensionist,” which has been regarded as normative, and the “sacrificialist,” which is more radical and less appreciated. While the extensionist Mencius operates on the assumption of congruity between the personal, the familial, and the political domains, the sacrificialist Mencius recognizes the ultimate incommensurability between the familial and the political and embraces the necessity for self-sacrifice in order to protect the familial. The hero of the sacrificialist Mencius is none other than the legendary sage-king, Shun 舜.

Bounded Traveling Wave Solution of a Nonlinear Equation

Jiang Tao,Yang Zhiyan,Liu Zhengrong 경북대학교 자연과학대학 수학과 2003 Kyungpook mathematical journal Vol.43 No.1

Bifurcation method of dynamical systems is applied to investigate traveling waves of nonlinear equation[a(1 + bu)u ]ux + uxxx = 0with =a,= > 0. Parameter space is partitioned. Types of bounded traveling waves are shown, that is, the equation has three types of bounded traveling waves, solitary waves,periodic waves and domain wall waves. When integral constant is zero, explicit expressions of bounded traveling wave solutions are obtained.

Genistein attenuates isoflurane-induced neurotoxicity and improves impaired spatial learning and memory by regulating cAMP/CREB and BDNF-TrkB-PI3K/Akt signaling

Tao Jiang,Xiu-qin Wang,Chuan Ding,Xue-lian Du 대한약리학회 2017 The Korean Journal of Physiology & Pharmacology Vol.21 No.6

Anesthetics are used extensively in surgeries and related procedures to prevent pain. However, there is some concern regarding neuronal degeneration and cognitive deficits arising from regular anesthetic exposure. Recent studies have indicated that brain-derived neurotrophic factor (BDNF) and cyclic AMP response element-binding protein (CREB) are involved in learning and memory processes. Genistein, a plant-derived isoflavone, has been shown to exhibit neuroprotective effects. The present study was performed to examine the protective effect of genistein against isoflurane-induced neurotoxicity in rats. Neonatal rats were exposed to isoflurane (0.75%, 6 hours) on postnatal day 7 (P7). Separate groups of rat pups were orally administered genistein at doses of 20, 40, or 80 mg/kg body weight from P3 to P15 and then exposed to isoflurane anesthesia on P7. Neuronal apoptosis was detected by TUNEL assay and FluoroJade B staining following isoflurane exposure. Genistein significantly reduced apoptosis in the hippocampus, reduced the expression of proapoptotic factors (Bad, Bax, and cleaved caspase-3), and increased the expression of Bcl-2 and Bcl-xL. RT-PCR analysis revealed enhanced BDNF and TrkB mRNA levels. Genistein effectively upregulated cAMP levels and phosphorylation of CREB and TrkB, leading to activation of cAMP/CREB-BDNF-TrkB signaling. PI3K/Akt signaling was also significantly activated. Genistein administration improved general behavior and enhanced learning and memory in the rats. These observations suggest that genistein exerts neuroprotective effects by suppressing isoflurane-induced neuronal apoptosis and by activating cAMP/CREB-BDNF-TrkB-PI3/Akt signaling.

Flexural performance of fire damaged and rehabilitated two span reinforced concrete slabs and beams

Jiang-Tao Yu,Yuan Liu,Zhou-Dao Lu,Kai Xiang 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.6

Five two-span reinforced concrete (RC) slabs and seven two-span RC beams were tested under the ISO 834 standard fire with different durations. CFRP strengthening was then applied to some of the specimens after the damaged concrete was removed from the specimens and replaced with polymer mortar. All the specimens were loaded to failure to investigate the influence of fire-damage and the effectiveness of strengthening methods. Test results indicated that the flexural capacities of specimens decrease with the fire duration increases. Moreover, fire exposure had more significant effect on the flexural rigidity than on the bearing capacity of the specimens. After rehabilitation, the bearing capacities of specimens reached or even exceeded that of the reference RC specimen, and the strengthening methods seemed to have limited effect on flexural rigidity recovery. From the analysis of moment redistribution of tested beams, elevated temperature is found having different impacts on sagging moment region and hogging moment region. The damage of RC continuous member is definitely a comprehensive response of different regions.