The influence of moisture on atmospheric pressure plasma etching of PA6 films

Zhiqiang Gao,Shujing Peng,Jie Sun,Lan Yao,Yiping Qiu 한국물리학회 2010 Current Applied Physics Vol.10 No.1

The moisture in the substrate material may have a potential influence on atmospheric pressure plasma treatment. In order to investigate how the existence of moisture affects atmospheric pressure plasma treatment, polyamide 6 (PA6) films were treated by helium, helium/oxygen (O2) plasmas using atmospheric pressure plasma jet (APPJ) at different moisture regain. The film surfaces were investigated using contact-angle measurements, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to characterize the surfaces. The exposure of PA6 film surfaces to the plasmas led to the etching process on the surfaces and changes in the topography of the surfaces. It was shown that the etching rate and the surface roughness were higher for the 9.33% moisture regain (relative humidity 100%) group than that of the 1.61% moisture regain (relative humidity 10%) group with the same plasma gas and power.

Effect of Freeze-Thaw Cycles on Dynamic Characteristics of Undisturbed Silty Clay

Gao Hang Cui,Zhuo Cheng,Daili Zhang,Shuxian Ma,Zhiqiang Liu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.9

We conducted dynamic triaxial tests of undisturbed soil samples under different control parameters using the Global Digital Systems (GDS) dynamic triaxial instrument. We investigated the dynamic and engineering characteristics of undisturbed soil under a freeze–thaw cycle. When the dynamic load amplitude and the number of freeze–thaw cycles were adjusted, we explored the cumulative plastic strain, dynamic elastic modulus, and dynamic strength of undisturbed soil, and we then proposed appropriate fitting formulae to compute the cumulative plastic strain, dynamic elastic modulus, and dynamic strength. The findings revealed that as the number of freeze–thaw cycles increased, the cumulative plastic strain grew, the dynamic strength progressively fell, and the dynamic elastic modulus dropped first, but then increased. The critical physical and dynamic features of soil changed dramatically during one to six freeze–thaw cycles. This study’s suggested formula for the average growth ratio can directly reflect the cumulative plastic strain fluctuation of soil throughout freeze–thaw cycles. The formula has a good fitting effect on undisturbed soil, according to the test findings, and the accumulative plastic strain, dynamic elastic modulus, and dynamic strength may be computed within a specified range. The findings of this study contribute to a better understanding of the effect of the freeze–thaw cycle on the dynamic characteristics of undisturbed silty clay, as well as a theoretical foundation for the design and construction of silty clay highway subgrade in seasonally frozen regions as well as the dynamic analysis of vehicle simulation in seasonally frozen regions.

Determining the Walker exponent and developing a modified Smith-Watson-Topper parameter model

Zhiqiang Lv,Hong-Zhong Huang,Hai-Kun Wang,Huiying Gao,Fang-Jun Zuo 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3

Mean stress effects significantly influence the fatigue life of components. In general, tensile mean stresses are known to reduce the fatigue life of components, whereas compressive mean stresses are known to increase it. To date, various methods that account for mean stress effects have been studied. In this research, considering the high accuracy of mean stress correction and the difficulty in obtaining the material parameter of the Walker method, a practical method is proposed to describe the material parameter of this method. The test data of various materials are then used to verify the proposed practical method. Furthermore, by applying the Walker material parameter and the Smith-Watson-Topper (SWT) parameter, a modified strain-life model is developed to consider sensitivity to mean stress of materials. In addition, three sets of experimental fatigue data from super alloy GH4133, aluminum alloy 7075-T651, and carbon steel are used to estimate the accuracy of the proposed model. A comparison is also made between the SWT parameter method and the proposed strainlife model. The proposed strain-life model provides more accurate life prediction results than the SWT parameter method.

Mechanical properties and neural network prediction of cement fly ash-enhanced roadbed soil in seasonal frozen zones under short-term curing

Gao Hang Cui,Zhuo Cheng,Fanyue Sun,Shuxian Ma,Zhiqiang Liu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1

The freezing and thawing of roadbed soils in seasonal frozen zones can cause uneven settlement and other road problems, which puts road operation at risk. This paper focuses on the rapid construction of expressways and analyzes the effects of using fly ash and cement as modifiers on the physical properties and chemical composition of subgrade soil. The study found that cement admixtures can improve soil mechanical attributes and frost resistance, while also increasing the degree of fly ash hydration.And the freeze-thaw cycle process can enhance the mechanical characteristics of soils with higher cement admixture content. This is due to the development of hydrates in cement fly ash-enhanced soils during freeze?thaw cycles, resulting in a denser interior structure. The use of neural network prediction analysis showed that using ANN4-10-3 to forecast soil mechanical property parameters can produce superior results. Therefore, it is recommended to use cement fly ash-enhanced soil for roadbed construction in seasonal freezing areas, and neural network can be used to predict soil mechanical parameters.

MODELLING, ANALYSIS AND SIMULATION OF A NOVEL AUTOMATED MANUAL TRANSMISSION WITH GEARSHIFT ASSISTANT MECHANISM

Zhiqiang Sun,Bingzhao Gao,Jiaqi Jin,Kazushi Sanada 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.5

To eliminate or reduce torque interruption and driveline jerk for traditional automated manual transmission (AMT), AMT with a gearshift assistant mechanism (GAM) is originally proposed in this paper. The GAM consists of a torque complementary motor and an epicyclic mechanism with a synchronizing clutch. During gear upshift, the electrical motor provides complementary torque to primary (output) shaft after synchronizer discharges, then the synchronizing clutch will work to synchronize primary shaft with anticipated gear. The lockup of the synchronizing clutch will ensure the synchronization of primary shaft and anticipated gear. After finishing synchronizing, synchronizer will lock up the anticipated gear and engine recovers torque supply to finish gearshift. Based on the mathematical model of the proposed transmission, its detailed structure, kinematic character and dynamic behavior are discussed. Controllers are designed to achieve presumed gearshift performance, and simulation results show its effectiveness. Problems may be encountered in engineering application and possible application on electrical vehicle (EV) of the proposed transmission are also discussed. Finally, this paper summarized the merits and further research targets of the proposed transmission, which is a promising structure to achieve swift and smooth gearshift.

The genetic divergence and genetic structure of two closely related fish species Lateolabrax maculatus and Lateolabrax japonicus in the Northwestern Pacific inferred from AFLP markers

Zhiqiang Han,Gang Han,Zhiyong Wang,Bonian Shui,Tianxiang Gao 한국유전학회 2015 Genes & Genomics Vol.37 No.5

Amplified fragment length polymorphism markers were used to estimate the genetic divergence and genetic structure of Lateolabrax maculatus, L. japonicus and their possible hybrid populations in the Northwestern Pacific. Ninety one individuals were sampled from nine localities including two putative hybrid samples across the distribution range of the two species. Five primer combinations generated a total of 423 loci among 91 individuals of L. maculatus and L. japonicus, 266 of which were polymorphic (62.88 %). The percentage of polymorphic loci in three populations of L. maculatus and five populations of L. japonicus ranged from 31.96 % (Beihai) to 37.94 % (Weihai), 31.05 % (Ishikawa) to 49.29 % (Yatsushiro Sea), respectively. The UPGMA tree constructed with individuals of both species indicated reciprocal monophyletic relationship between L. japonicus and L. maculatus. Hybrid individuals between the two species in Ariake Sea and Yatsushiro Sea were identified by UPGMA tree and principal component analysis (PCA). The sympatry of two clades in the Yatsushiro Sea gave the first evidence of possible reproductive isolation between hybrid and L. japonicus. AMOVA analysis and pairwise FST revealed significant genetic differentiation within both species, indicating limited dispersal ability in two species. Historical isolation coupled with low dispersal ability was responsible for the genetic divergence between species and significant genetic structure in the two species.

POWER LOSS EVALUATION OF AUTOMATED MANUAL TRANSMISSION WITH GEARSHIFT ASSISTANT MECHANISM

Zhiqiang Sun,Bingzhao Gao,Jiaqi Jin,Kazushi Sanada 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.2

This paper deals with the power loss evaluation in gearshift assistant mechanism applied in automated manual transmission. The originalities include building the numerical models of gearshift assistant mechanism efficiency analysis for cost penalty evaluation and designing gear ratio matching algorithm to match the gear ratios of epicyclic mechanism with desired ones, which is expected to minimize the clutch friction losses by reducing the angular velocity differences between two clutch pads. In the numerical models, gear meshing losses and friction losses are considered the main power sink. By the kinematic relationships and power flow analysis, a set of generalized efficiency calculating formulas of simple epicyclic mechanism in six working modes with respect to teeth numbers are summarized, which are useful computer-aided tools in calculating multiple simple epicyclic mechanisms’ efficiency. The matched gear ratios and the efficiency models are tested on a powertrain simulation model and several simulation results are reported. Finally, this paper summarized the merits and further research targets of the proposed transmission, which is a promising structure to achieve swift and smooth gearshift with low power losses.

Lifetime prediction for turbine discs based on a modified Walker strain model

Zhiqiang Lv,Hong-Zhong Huang,Huiying Gao,Fang-Jun Zuo,Hai-Kun Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

We created three-dimensional models of turbine disc and blades of a type of aero-engine according to their geometries. Extant studies show that low cycle fatigue is the main failure mechanism of turbine disc. By using a non-linear elastic-plasticfinite element method, the static stress and strain state of the critically high stress regions, which can lead to operational failures,are determined. On the basis of stress-strain relation, a modified Walker strain life prediction model is proposed with norequired knowledge on the mean stress correction. Then the predicted life data from the modified Walker strain model arecompared with the testing results. After the verification, the modified Walker strain life prediction model and Miner’s rule wereapplied to predict the lifetime of the turbine disc under various operating conditions.

An improved Corten-Dolan’s model based on damage and stress state effects

Huiying Gao,Hong-Zhong Huang,Zhiqiang Lv,Fang-Jun Zuo,Hai-Kun Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

The value of exponent d in Corten-Dolan’s model is generally considered to be a constant. Nonetheless, the results predicted on thebasis of this statement deviate significantly from the real values. In consideration of the effects of damage and stress state on fatigue lifeprediction, Corten-Dolan’s model is improved by redefining the exponent d used in the traditional model. The improved model performsbetter than the traditional one with respect to the demonstration of a fatigue failure mechanism. Predictions of fatigue life on thebasis of investigations into three metallic specimens indicate that the errors caused by the improved model are significantly smaller thanthose induced by the traditional model. Meanwhile, predictions derived according to the improved model fall into a narrower dispersionzone than those made as per Miner’s rule and the traditional model. This finding suggests that the proposed model improves the life predictionaccuracy of the other two models. The predictions obtained using the improved Corten-Dolan’s model differ slightly from thosederived according to a model proposed in previous literature; a few life predictions obtained on the basis of the former are more accuratethan those derived according to the latter. Therefore, the improved model proposed in this paper is proven to be rational and reliable giventhe proven validity of the existing model. Therefore, the improved model can be feasibly and credibly applied to damage accumulationand fatigue life prediction to some extent.

Lactic acid bacterial inoculant effects on the vitamin content of alfalfa and Chinese leymus silage

Tingting Jia,Zhiqiang Sun,Run Gao,Zhu Yu 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.12

Objective: Information regarding the vitamin content of silage is limited. This study investigated the changes in the vitamin content of alfalfa and Chinese leymus silages with or without a lactic acid bacterial inoculant. Methods: Alfalfa at the early flowering stage and Chinese leymus at the full-bloom stage were harvested. The treatments for each forage type were control (deionized water only) and 1×106 colony-forming units Lactobacillus plantarum (LP)/g fresh matter. After 45 days of ensiling, all silages were sampled for evaluating the vitamin content, fermentation quality and chemical composition. Results: The LP inoculant decreased the pH value and ammonia nitrogen content of the alfalfa and Chinese leymus silages and significantly (p<0.05) increased the lactic acid, acetic acid concentrations and Flieg’s points. Prior to ensiling, the levels of five B-group vitamins (thiamin, riboflavin, niacin, pantothenic acid, and pyridoxine) and α-tocopherol in alfalfa were significantly (p<0.01) higher than those in Chinese leymus. Ensiling decreased the levels of the five B-group vitamins in both alfalfa and Chinese leymus while increasing the α-tocopherol content of Chinese leymus. The thiamin, riboflavin, niacin and pantothenic acid levels in the LP-treated silage were significantly (p<0.05) lower than those in the untreated silage for the alfalfa and Chinese leymus. The α-tocopherol content in the LP-treated alfalfa silage was significantly (p<0.05) higher than that in the untreated alfalfa silage. There was no significant (p>0.05) difference in pyridoxine content between the untreated and LP-treated silages for both forages. Conclusion: With or without LP inoculation, the levels of the five B-group vitamins (thiamin, riboflavin, niacin, pantothenic acid, and pyridoxine) in alfalfa and Chinese leymus decreased after 45 days of ensiling, while the α-tocopherol content of Chinese leymus increased. The LP inoculant improved the fermentation quality of both the alfalfa and Chinese leymus silages but increased the thiamin, riboflavin, niacin, and pantothenic acid loss in the two forages after fermentation.