Evaluation of Rock Vibration Generated in Blasting Excavation of Deep-buried Tunnels

Jianhua Yang,Wenbo Lu,Peng Yan 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.7

The experimental tunnels of the China Jinping Underground Laboratory are constructed in a maximum overburden depth of 2375 mand subjected to extremely high in situ stress more than 50 MPa. When these deep-buried tunnels are excavated with the method ofdrill and blast, the surfaces created by blasting are generated almost instantaneously, and thus the initial stress on these surfaces is alsosuddenly released. This transient release of in situ stress causes elastic waves to propagate in rock masses and may have an importanteffect on the subsequent rock vibration. In this study, a three-dimensional FEM modeling in combination with site investigation isconducted to research the Peak Particle Velocity (PPV) attenuation and frequency characteristics for the rock vibration induced bytransient stress release and its combined actions with blast loading. The results indicate that the transient release of the high stressgenerates considerable vibration velocity that is comparable to that of blast loading. It is not a negligible excitation for the rockvibration generated in blasting excavation of deep-buried tunnels. Furthermore, the vibration induced by transient stress release hasmuch lower frequency than that caused by blast loading. This causes the unloading vibration to decay more slowly and become themajor vibration component at far distances. Also, the effect of transient stress release is found to enhance intensity of the totalvibration and furthermore cause an increase in its low-frequency content. On the basis of this, the allowable charge amount per delayand the minimum safety distance are finally discussed with a special emphasis on the contributions of the transient stress release tothe total vibration.

1,4-Di(3-alkoxy-2-thienyl)-2,5-difluorophenylene: A Building Block Enabling High-Performance Polymer Semiconductors with Increased Open-Circuit Voltages

Chen, Jianhua,Yan, Zhenglong,Tang, Linjing,Uddin, Mohammad Afsar,Yu, Jianwei,Zhou, Xin,Yang, Kun,Tang, Yumin,Shin, Tae Joo,Woo, Han Young,Guo, Xugang American Chemical Society 2018 Macromolecules Vol.51 No.14

<P>A new building block, 1,4-di(3-alkoxy-2-thienyl)-2,5-difluorophenylene (DOTFP) with several desirable features such as high backbone planarity, suitably lying highest occupied molecular orbital (HOMO), and good solubility, was developed by inserting an electron-deficient difluorophenylene into the 3,3′-dialkoxy-2,2′-bithiophene (BTOR) unit. Three regioregular D-A<SUB>1</SUB>-D-A<SUB>2</SUB> type polymers based on DOTFP and benzothiadiazole (BT) derivatives were synthesized and characterized by comparing with a D-A type BTOR-based polymer. The content of highly electron-rich alkoxythiophene is reduced by half in the DOTFP-based polymers versus that of the BTOR-based polymer analogue, which results in a deeper HOMO level and benefits high open-circuit voltage (<I>V</I><SUB>oc</SUB>) in polymer solar cells (PSCs). Consequently, the DOTFP-ffBT-based solar cells exhibited a significantly improved power conversion efficiency (PCE) of 8.7% and an increased <I>V</I><SUB>oc</SUB> of 0.84 V compared to the BTOR-ffBT-based solar cells with a PCE of 2.6% and a <I>V</I><SUB>oc</SUB> of 0.49 V. Additionally, the DOTFP-based polymers showed improved charge transport properties and film morphology than the BTOR-based polymer BTOR-ffBT, resulting in simultaneous enhancement of the short-circuit current (<I>J</I><SUB>sc</SUB>) and fill factor (FF) in PSCs. These results demonstrate the great promise of the DOTFP building block for the construction of high-performance photovoltaic polymer semiconductors with increased <I>V</I><SUB>oc</SUB>s.</P> [FIG OMISSION]</BR>

A Novel Robust Neural Network Sliding-Mode Control Method for Synchronizing Fractional Order Chaotic Systems in the Presence of Uncertainty, Disturbance and Time-Varying Delay

Gu Yan,Sun Jianhua,Fu Xiuwei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

Given the importance of synchronization in chaotic systems, this paper presents a new approach to achieve this goal. Simultaneous consideration of time-varying delays, disturbances, uncertainties, and nonlinear terms in a fractional order chaotic system poses a fundamental challenge for achieving the synchronization goal and this paper presents a novel complex approach resulting from neural network and sliding mode approaches to overcome it. The Chebyshev neural network has been used to estimate the delayed nonlinear functions as well as the uncertain parts of the fractional order chaotic system, and the robust sliding mode technique has been considered to ensure stability against the effects of multiple inconveniences. Finally, simulation and comparison in MATLAB environment confirms the efficiency and ability of the proposed scheme in achieving the goal of robust synchronization despite the uncertainty, variable time delay, disturbance and nonlinear terms.

CONCEPT OF RIVER HEALTH

WENHUI YANG,JIANHUA WU,ZHONGMIN YAN 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Mechanical and Thermal Properties of Epoxy Resins Modified by a Novel Thermoplastic-polyimide

Yu Ji,Yan Zhang,Ping Wang,Yuanyuan Li,Jianhua Sui 한국섬유공학회 2021 Fibers and polymers Vol.22 No.1

In this paper, a novel polyimide with trifluoromethyl group (PIS) was synthesized successfully and used toimprove the toughness of epoxy resins. Five modified epoxy resins (5, 7.5, 10, 12.5 and 15 wt%) were prepared andinvestigated, respectively. The structure, thermal properties, tensile properties, viscoelastic properties, toughness andmorphology of modified epoxy resins were studied by Fourier Transform Infrared Spectroscopy (FT-IR), thermogravimetricanalysis (TGA), Instron 5967, Dynamic Mechanical Analysis (DMA), and Scanning Electron Microscopy (SEM). Theresults showed that the epoxy resins modified with PIS exhibited good thermal stability which the glass transitiontemperatures increased from 135.9 oC to 146.4 oC. Tensile strength of modified epoxy resins increased from 40.4 MPa to92.3 MPa. The KIC values increased from 0.86 MPa·m1/2 to 1.56 MPa·m1/2 indicated that the toughness enhancement wasmarkedly. The fracture modes also were examined by SEM images and exhibited the fracture mode changed from the brittleone to ductile fracture with varied weight of the novel trifluoromethyl-polyimide.

Morphology characterization of micro-gap oil film of tilting pad hydrostatic bearing under extreme working conditions

Xiaodong Yu,Yanan Feng,Yan Zhao,Dianbin Huang,Jianhua Jiao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12

Taking the hydrostatic support of the tiltable oil pad double rectangular cavity as the object, the fluid-thermal-solid coupling deformation analysis of the friction pair is carried out, and the three-dimensional morphology of the micro-gap oil film is obtained. An oil film thickness test device is built to verify the rationality of the numerical simulation method. It is found that the elastic deformations of rotational workbench and base under extreme loads are both concave deformations, the thermal deformations are both convex deformations, and the maximum thermal deformation is mainly concentrated on the outer oil sealing edge. The deformation of the downstream side oil sealing edge is higher than that of the reverse side oil sealing edge. The minimum oil film thickness is the minimum distance between the downstream side oil sealing edge and the lower surface of the hydrostatic guideway of the rotational workbench, where tribological failure is prone to occur.

Effective reduction in chimeric mutants of poplar trees produced by CRISPR/Cas9 through a second round of shoot regeneration

Liping Ding,Yajuan Chen,Yan Ma,Hongzhi Wang,Jianhua Wei 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.5

The clustered regulatory interspaced short palindromic repeat/CRISPR-associated protein 9 (CRISPR/Cas9) system has been applied to edit the genomes of quite a few plant species, including perennial woody poplar trees. However, chimeras often exist in primary transgenic plants. For perennial woody trees such as poplar trees, it is difcult to obtain homozygous mutants by self-pollination for due to their long vegetative life and low-seed setting rates. In this study, we report an efec�tive approach to reduce the frequency of chimeric mutants of poplar trees by CRISPR/Cas9 with a second round of shoot regeneration using leaves as the explants. PdbPDS1 was used as the target gene, and only one homozygous PdbPDS1 mutant was obtained from 15 primary transgenic plantlets, which was verifed by both the phenotype and the DNA sequence of the PCR product. This indicates that the majority of primary transgenic plantlets in the T0 generation were chimeras. After the second round of shoot regeneration of the chimeric mutants generated by CRISPR/Cas9, approximately 27.0% or 19.1% of the regenerated shoots were homozygous mutants with or without kanamycin selection, respectively. The results showed that a second regeneration could produce homozygous mutant shoots at a high frequency and that kanamycin selection could increase the frequency of homozygous mutant shoots.

A (k,t,n) verifiable multi-secret sharing scheme based on adversary structure

( Jing Li ),( Licheng Wang ),( Jianhua Yan ),( Xinxin Niu ),( Yixian Yang ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.12

A (n,t,n) secret sharing scheme is to share a secret among n group members, where each member also plays a role of a dealer,and any t shares can be used to recover the secret. In this paper, we propose a strong (k,t,n) verifiable multi-secret sharing scheme, where any k out of n participants operate as dealers. The scheme realizes both threshold structure and adversary structure simultaneously, and removes a trusted third party. The secret reconstruction phase is performed using an additive homomorphism for decreasing the storage cost. Meanwhile, the scheme achieves the pre-verification property in the sense that any participant doesn`t need to reveal any information about real master shares in the verification phase. We compare our proposal with the previous (n,t,n) secret sharing schemes from the perspectives of what kinds of access structures they achieve, what kinds of functionalities they support and whether heavy storage cost for secret share is required. Then it shows that our scheme takes the following advantages: (a) realizing the adversary structure, (b) allowing any k out of n participants to operate as dealers, (c) small sized secret share. Moreover, our proposed scheme is a favorable candidate to be used in many applications, such as secure multi-party computation and privacy preserving data mining, etc.

Influence of Molecular Weight on the Dielectric and Energy Storage Properties of Poly(vinylidene fluoride)

Yuetao Zhao,Wenyao Yang,Yujiu Zhou,Yan Chen,Yajie Yang,Jianhua Xu,Yadong Jiang 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.6

The molecular weight shows great influence on dielectricand energy storage performance of poly(vinylidenefluoride) (PVDF) films and related devices. In this letter,the influences of molecular weight on the dielectric andenergy storage properties of PVDF films were studied. Ithas been found that, under a 1000 kV/cm electric field,the low-molecular-weight PVDF film presents a muchhigher energy storage efficiency as high as 80.10%,nearly three times as much as the high-molecular-weightPVDF film. Moreover, the low-molecular-weight PVDFfilm also shows high resistivity, representing an order ofmagnitude improvement over the high-molecular-weightPVDF film, which is more desirable and promising forhigh performance pulse discharge capacitor application.

Douglas-Peucker-Based Accelerated Similarity Measures for Massive AIS Trajectories

Kai WANG,Ryan Wen LIU,Yan LI,Maohan LIANG,Yi LIU,Jianhua WU,Jingxian LIU 국제이네비해양경제학회 2017 International Journal of e-Navigation and Maritime Vol.8 No.1

With the rapid development of the global economy, transport safety and security have become the key issues in maritime transportation all over the world. In practical applications, the Automatic Identification System (AIS)-based measurement of similarities between different vessel trajectories plays an important role in improving maritime transportation, e.g., maritime navigation, maritime supervision and management. However, the received AIS datasets are usually composed of a large amount of redundant information which could significantly increase the computational complexity. To deal with this problem, a Douglas-Peucker (DP)-based calculation method is introduced in this paper to accurately compress the spatio-temporal AIS trajectories while preserving the main geometrical structures. Based on the compressed trajectories, it is able to accelerate the Dynamic Time Warping (DTW) algorithm for the measurement of similarities between different vessel trajectories. In particular, the combination of DP and DTW has the capacity of significantly reducing the computational cost and guaranteeing the accuracy of similarity measures. The experimental results have demonstrated the superior performance of the proposed method in terms of computational cost and accuracy of similarity measures.