3-D Seismic Images of Crust and Upper Mantle beneath Bohai Basin and its adjacent regions, Eastern China

Liu, Jianhua,Liu, Futain,He, Jiankun,Chen, Hui Korean Society of Earth and Exploration Geophysici 2000 지구물리 Vol.3 No.4

본 연구는 동지나 분지에서의 지각변형, 3차원적 지진파 속도 분포 및 화산암 원소의 지화학적 추적을 통하여, 분지의 지체구조적 및 대륙의 지체동역학적인 해석을 목적으로 수행되었다 This research was carried out in order to give some reasonable solutions on basin tectonics and on continental geodynamics, which are approached by using integrative researches on crustal deformation, 3-D seismic velocity reconstruction and geochemical tracing of volcanic rocks in the eastern China basin system.

The Mechanical Properties of Lean Clay Filler under Freeze-thaw and Thermostatic Curing Cycles in Loess Plateau

Xiaoqiang Liu,Jiankun Liu,Yahu Tian,Yupeng Shen,Dan Chang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

The subgrade filler weakens its mechanical property after suffering from freeze-thaw (F-T) cycles, which threatens the trains' operation safety. It is essential to study the filler's mechanical property's evolution with the F-T cycles and reveal the test factors' incidence on the mechanical parameters. This study conducted a series of unconsolidated and undrained (UU) triaxial shear tests in the F-T and thermostatic-curing (T-C) groups, considering the temperature, confining pressure, and cycle times. As the control group, the T-C group can more prominently reflect the F-T effects on the soil's mechanical parameters, including the stress-strain curve, shear strength, and strength index. A piecewise and linear function can fit internal friction angle or cohesion's change with cycle times, respectively. The fitting parameters reflect the T-C and F-T effects on soil's mechanical properties. The absolute degree of incidence reveals the correlation between mechanical parameters and test factors. The -15°C has the most significant incidence than -5°C and 20°C in shear strength, while -5°C has the most considerable incidence than -15°C and 20°C in friction angle or cohesion. The water distribution and volume expansion due to the F-T cycles are the main reasons determining mechanical properties' evolution with the cycle times in different negative temperatures.

Effect of blade tip pattern on blade load and vibration characteristics of a twin-stage axial flow fan

Jiankun Zhang,Haihu Liu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

Focusing on a twin-stage axial fan, this paper investigates the effect of blade tip pattern on blade load and vibration characteristics. Steady simulations are first conducted to quantify the aerodynamic performance of various blade tip patterns. The finite element modeling analysis is performed to capture blade load and vibration characteristics, and Campbell diagram is introduced to evaluate resonance margin of different blade tip patterns. Results show that for all selected patterns, the first three mode shapes are mainly the bending of blade tip, which results in stress concentration at the blade root, while the last three are the waving in small range. The proposed blade tip patterns not only increase maximum stress and average deformation, but also significantly increase resonance margin near the rated speed. In addition, based on the harmonic response analysis, we find that the stress and amplitude frequency response will be notably altered by blade tip patterns.

Flexibility and Thermal Storage Properties of Polyurethane Adhesive Supported Phase Change Composites Based on Polyurethane Phase Change Materials

Jiankun Dong,Wenzhao Shi,Jinshu Liu,Shaofeng Lu,Hongjuan Zhou,Shanshan Cui,Manyan Zhang,Guoxin Su 한국섬유공학회 2023 Fibers and polymers Vol.24 No.9

Polyurethane phase change materials (PUPCMs) have been extensively applied in smart textiles and wearable electronic devices because of their excellent energy storage capacity. To realize the flexibility of PUPCMs for certain deformation and compact contact with objects, suitable support structures have been chosen to prepare polyurethane phase change composites (PUFPCCs) with energy storage capacity and device-level flexibility. In this work, PUPCM was prepared by the prepolymer method with polyethylene glycol (PEG) as the soft segment, 4,4-dicyclohexylmethane diisocyanate (HMDI) and 1,2-hexanediol as the hard segment. And polyurethane-based adhesives (PUA) were chosen to provide a support structure for PUFPCCs by physically blending and casting with prepared PUPCM. PUFPCCs showed good flexibility attributed to the film-forming performance of polyurethane-based adhesive in the composites. The chemical structure, crystallization properties, phase transformation properties and thermal stability of the prepared PUPCM and PUFPCCs were investigated via Fourier transform infrared spectroscopy (FT-IR), 1H NMR spectroscopy, X-ray diffraction (XRD), polarizing optical microscope (POM), differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis respectively. The phase change temperature of PUFPCCs ranged from 36 to 40 ℃. The maximum enthalpy value of PUFPCCs was up to 40 J/g for daily application. Moreover, the thermal stability of PUPCM was improved attribute to the support structure of PUA in PUFPCCs. Therefore, the prepared PUFPCCs have great potential for application in flexible wearable devices due to their excellent flexibility, suitable phase transition temperature close to human body temperature, high enthalpy value and improved thermal stability.

Effect of Freeze-Thaw Cycles on Triaxial Strength Properties of Fiber-Reinforced Clayey Soil

Muge Elif Orakoglu,Jiankun Liu 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.6

Understanding effect of freezing phenomenon in a fiber-reinforced soil structure is essential to foundation technology, road construction and earthwork application in cold region. This research aims to present the results of experimental investigation relative to the unconsolidated-undrained triaxial compression behavior of fine-grained soil as a function of freeze-thaw cycles and fiber volume fractions. All measurements were carried out for 3 selected glass and basalt fiber fractions (0%, 0.5%, and 1%) and 5 selected freeze-thaw cycles (0, 2, 5, 10, and 15). It has been observed that for the studied soil, strength of unreinforced soil reduced with increasing number of the freeze-thaw cycles while fiber-reinforced soil shows greater effect and the strength reduction amount reduces from 40% to 18%. Moreover, the reduction trend for cohesion of the fiber-reinforced soil decreased, this was seen more prevalent on 1% glass fiber-reinforced soil. The resilient modulus of all specimens reduced with increasing number of the freezethaw cycles. The experimental results demonstrated that different fiber fractions and their mixtures could be employed as supplement additive to improve the freeze-thaw performance of cohesive soils for road construction and earthworks.

Numerical simulation of pressure relief in hard coal seam by water jet cutting

Song, Dazhao,Wang, Enyuan,Xu, Jiankun,Liu, Xiaofei,Shen, Rongxi,Xu, Wenquan Techno-Press 2015 Geomechanics & engineering Vol.8 No.4

The applications of water jet cutting (WJC) in coal mine have progressed slowly. In this paper, we analyzed the possibility and reasonableness of WJC application to pressure relief in hard coal seam, simulated the distributive characteristics of stress and energy fields suffered by hard coal roadway wallrock and the internal relationships of the fields to the instability due to WJC (including horizontal radial slot and vertical annular slot) on roadway wallrock. The results showed that: (1) WJC can unload hard coal seam effectively by inducing stress release and energy dissipation in coal mass near its slots; its annular slots also can block or weaken stress and energy transfer in coal mass; (2) the two slots may cause "the beam structure" and "the small pillar skeleton", and "the layered energy reservoir structure", respectively, which lead to the increase in stress concentration and energy accumulation in coal element mass near the slots; (3) the reasonable design and optimization of slots' positions and their combination not only can significantly reduce the scope of stress concentration and energy accumulation, but also destroy coal mass structure on a larger scale to force stress to transfer deeper coal mass.

A Comprehensive Model for Wind Power Forecast Error and its Application in Economic Analysis of Energy Storage Systems

Huang, Yu,Xu, Qingshan,Jiang, Xianqiang,Zhang, Tong,Liu, Jiankun The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

The unavoidable forecast error of wind power is one of the biggest obstacles for wind farms to participate in day-ahead electricity market. To mitigate the deviation from forecast, installation of energy storage system (ESS) is considered. An accurate model of wind power forecast error is fundamental for ESS sizing. However, previous study shows that the error distribution has variable kurtosis and fat tails, and insufficient measurement data of wind farms would add to the difficulty of modeling. This paper presents a comprehensive way that makes the use of mixed skewness model (MSM) and copula theory to give a better approximation for the distribution of forecast error, and it remains valid even if the dataset is not so well documented. The model is then used to optimize the ESS power and capacity aiming to pay the minimal extra cost. Results show the effectiveness of the new model for finding the optimal size of ESS and increasing the economic benefit.

A Comprehensive Model for Wind Power Forecast Error and its Application in Economic Analysis of Energy Storage Systems

Yu Huang,Qingshan Xu,Xianqiang Jiang,Tong Zhang,Jiankun Liu 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

The unavoidable forecast error of wind power is one of the biggest obstacles for wind farms to participate in day-ahead electricity market. To mitigate the deviation from forecast, installation of energy storage system (ESS) is considered. An accurate model of wind power forecast error is fundamental for ESS sizing. However, previous study shows that the error distribution has variable kurtosis and fat tails, and insufficient measurement data of wind farms would add to the difficulty of modeling. This paper presents a comprehensive way that makes the use of mixed skewness model (MSM) and copula theory to give a better approximation for the distribution of forecast error, and it remains valid even if the dataset is not so well documented. The model is then used to optimize the ESS power and capacity aiming to pay the minimal extra cost. Results show the effectiveness of the new model for finding the optimal size of ESS and increasing the economic benefit.