Journal of University of Chinese Academy of Sciences

Research on the nonlinearity of nearshore water waves

ZHOU Zili, ZHANG Huai, SHI Yaolin

2019, 36 (4): 433-443. DOI: 10.7523/j.issn.2095-6134.2019.04.001

The research on the nonlinearity of nearshore water waves has a significant meaning in helping us to understand the physical characteristics of nearshore waves and currents, to utilize nearshore marine resources, and to assist the decision-making process of the hazard prediction and mitigation. In recent years, many new nonlinear nearshore wave equations were developed. However, because different processes have different topographical conditions and roughness, they adapt to different governing equations. It is necessary to know the application scopes and calculation efficiencies of the main nonlinear wave equations. This paper reviews the methods of nonlinearity classification and reviews the main nonlinear wave models and their applications for nearshore regions, including their physical properties and the degree of nonlinearity. This paper will help researchers to understand the nonlinearity of different nearshore issues and to choose a suitable simulation model.

K₁ groups of integral group rings for some types of finite abelian groups

WANG Zuoen, TANG Guoping

2019, 36 (4): 444-448. DOI: 10.7523/j.issn.2095-6134.2019.04.002

Abstract ( 363 ) PDF (KB) ( 1 )

Let G be a finite abelian group. Its integral group ring ZG is a Z-order in QG. Let Γ be the maximal Z-order in QG containing ZG. We calculate the index of K₁(ZG) in K₁(Γ) for some types of finite abelian groups.

Targeted local angle-based multi-category support vector machine

KANG Wenjia, LIN Wenhui, ZHANG Sanguo

2019, 36 (4): 449-460. DOI: 10.7523/j.issn.2095-6134.2019.04.003

Abstract ( 298 ) PDF (KB) ( 14 )

The support vector machine(SVM) is one of the most concise and efficient classification methods in machine learning. Traditional SVMs mainly handle with binary classification problems by maximizing the smallest margins. However, the real-world data are much more complicated. On the one hand, the label set usually has more than two categories, so SVMs need to be generalized for solving multi-category problems reasonably. On the other hand, there may exist one special variable which should be singled out to preserve its effect on the final results from other variables such as age in bioscience field. We name such a special variable as targeted variable. In this work, in order to take both aspects mentioned above into consideration, targeted local angle-based multi-category support vector machine(TLAMSVM) is proposed. This new model not only solves multi-category problems but also pays special attention to targeted variable. Moreover, TLAMSVM solves multi-classification in the framework of angle-based method, which provides a better interpretation from the geometrical viewpoint, and it uses local smoothing method to pool the information of targeted variable. In order to validate the classification effect of TLAMSVM model, we apply it to both simulated and real data sets, respectively, and get the expected results in numerical experiments.

Effect of broad bounce on primordial gravitational waves

ZHAO Jinyun, PIAO Yunsong

2019, 36 (4): 461-466. DOI: 10.7523/j.issn.2095-6134.2019.04.004

Abstract ( 326 ) PDF (KB) ( 12 )

The bounce inflation is successful in solving the initial singularity problem of inflation and is also competitive in explaining the power deficit in CMB at large scale. Generally, the duration that the bounce lasts is short (the so-called narrow bounce). However, the case of broad bounce is not ruled out. In this study, we focus on the tensor perturbation during the inflation with a broad bounce. We find that the power spectrum may be very different from that in narrow bounce model.

Energetics comparison between zebrafish C-shaped turning and escape: self-propelled simulation with novel curvature models

WANG Zhongwei, YU Yongliang

2019, 36 (4): 467-480. DOI: 10.7523/j.issn.2095-6134.2019.04.005

Abstract ( 370 ) PDF (KB) ( 2 )

The zebrafish C-start occurs not only in the escape response (C-escape), but also in the non-escape response (C-turn). They have different deforming modes and durations, and put in distinct kinematics performances. With the same bending amplitude, C-turns achieve larger turning angles, while C-escapes have higher velocities. However, little is known about their hydrodynamic mechanisms and energetics features. We proposed two novel curvature models based on the deformation characteristics of C-turn and C-escape, respectively. An optimization algorithm was used to determine the model parameters according to experimental data. Through self-propelled numerical simulation, we found that the positive moment at stage 1 of C-turn was large and the negative moment at stage 2 was small. So C-turn achieved a large turning angle. However, C-escape had a large thrust at stage 2, which led to the negative moment increasing and the turning angle reducing. We also found that the duration had little effect on the turning angle, but had a significant influence on escape velocity and energy consumption. Therefore, in order to save energy the duration of C-turn is usually over 100 ms, and the duration of C-escape is near 50 ms in order to pursue high speed.

3D numercial simulations of liquid metal jet under a horizontal magnetic field

YU Xingxing, ZHANG Jie, NI Mingjiu

2019, 36 (4): 481-486. DOI: 10.7523/j.issn.2095-6134.2019.04.006

Abstract ( 402 ) PDF (KB) ( 1 )

The liquid metal jet under a horizontal magnetic field plays a significant role in the fusion reactor. 3D numerical simulations of the liquid jet under a horizontal magnetic field are performed in this study, and we mainly study the breakup of the liquid jet at the low Weber numbers under different magnetic fields. The stability of the liquid metal jet changes in the magnetic field. The breakup length of the liquid metal jet grows with the increase of magnetic field. Meanwhile, the droplets form when the liquid metal jet breaks up. The volume of the droplet decreases with the increase of magnetic field. As the magnetic field increases, the wavelength of the interfacial disturbance wave increases due to the Lorentz force. In the case of a large Weber number, the magnetic field exerts a great influence on the interfacial disturbance. At the surface of the liquid metal jet, the 3D dilatational wave and sinuous wave become the 2D ones under the vertical magnetic field. Therefore, the stability of the liquid metal jet is significantly enhanced.

An effective method for calculating the critical Casimir force between two parallel plates for the Ising universality class

CHEN Dongyan, MIAO Bing

2019, 36 (4): 487-490. DOI: 10.7523/j.issn.2095-6134.2019.04.007

Abstract ( 477 ) PDF (KB) ( 5 )

Due to the constraints introduced by boundaries for the long range fluctuations in a massless field, a long-range fluctuation-induced effective force between boundaries is induced, and it is called the Casimir force. The classical Casimir force refers to the interaction between two conducting plates immersed in a vacuum, and it is originated from the quantum fluctuations of the electromagnetic field. In this work, we study the critical Casimir force for the Ising universality class in statistical mechanics. Specifically, we develop an effective method, namely, the Euler-Maclaurin summation method, to calculate the critical Casimir force between two parallel plates at the critical point of the Ising universality class. Our results demonstrate that, in this geometric set-up, the critical Casimir force behaves as a long-range attractive force with a scaling exponent of -3 with respect to the boundary distance.

An approach of improved gradient plus inverse distance squared for spatial interpolation of temperature

LI Kuangyu, ZHOU Mei, CHEN Jiuying, PAN Miaomiao, LI Chuanrong, TANG Lingli

2019, 36 (4): 491-497. DOI: 10.7523/j.issn.2095-6134.2019.04.008

Abstract ( 472 ) PDF (KB) ( 1 )

To reduce the large errors in spatial interpolation of temperature in terrains of salient relief using gradient plus inverse distance squared (GIDS) method, a method of empirical adiabatic rate-based gradient plus inverse distance squared (GIDS-EAR) is proposed in this work. In this method, the influences of horizontal position and altitude on temperature are considered separately in interpolation of temperature. First, the partial regression coefficient of temperature with altitude is determined based on the empirical adiabatic rate, and temperatures of the samples are corrected by using the partial regression coefficients. Next, the corrected temperature is substituted into a multiple linear regression model to calculate the partial regression coefficients of temperature with latitude and longitude. Then, the temperature to be interpolated is calculated using the GIDS method. The GIDS-EAR method is compared with Ordinary Kriging (OK), Inverse Distance Weighting (IDW), and GIDS methods on a dataset of monthly surface observation temperature from 1981 to 2010 from 219 meteorological stations in Sichuan and the surrounding provinces. The results show that the annual average MAE and RMSE values obtained by the GIDS-EAR method are 67.71% and 68.15% lower than those by the OK method, 67.68% and 66.45% lower than those by the IDW method, and 25.65% and 30.08% lower than those by the GIDS method, respectively. The testing results show the effectiveness and the applicability of the proposed method under complex terrain situations.

Relationships between surface soil magnetic susceptibility and modern climatic factors in eastern China and their environmental significance

GU Yongjian, LI Yumei, HAN Long, SU Xin

2019, 36 (4): 498-509. DOI: 10.7523/j.issn.2095-6134.2019.04.009

Abstract ( 499 ) PDF (KB) ( 19 )

For proper understanding of the relationships between magnetic susceptibility and environmental factors and the influence of climate, especially the temperature and precipitation, on magnetic susceptibility, surface soil samples were collected from two environmental transections, E-W and N-S, in eastern China, and the magnetic susceptibility of soil samples was measured. Spatial distribution characteristics of soil magnetic susceptibility and its relationships with modern climate parameters such as MAT, MARH, and MAP were analyzed. Results indicate that the χ_lf and χ_fd values are high in the east and low in the west in E-W transection and that χ_lf varies complicatedly with latitude and χ_fd declines toward the north in N-S transection. At 0℃ ≤ MAT ≤ 12℃ or MAP ≤ 1 000 mm, χ_lf rises with the increases of MAT and MAP. At MAT>12℃ or MAP>1 000 mm, χ_lf shows the opposite change. Precipitation plays a primary role in the process of weathering and pedogenesis, and the influence of temperature is secondary. The regression equations between χ_lf and MAP indicate that magnetic susceptibility can be used as a quantitative reconstruction proxy of paleoprecipitation. The research results show that the reconstruction of the paleoenvironment using magnetic susceptibility has certain limitation, and magnetic susceptibility reflects the change in paleoprecipitation well in the area with 200 ≤ MAP ≤ 1 000 mm.

Research progress in eco-environmental issues and eco-restoration strategy in Yongding River basin

FENG Zhaozhong, LIU Shuo, LI Pin

2019, 36 (4): 510-520. DOI: 10.7523/j.issn.2095-6134.2019.04.010

Abstract ( 505 ) PDF (KB) ( 2 )

In recent years, with fast urban agglomerations and expansion of the Beijing-Tianjin-Hebei (BTH) region, the Yongding River ecosystem was affected intensively and its ecological function was seriously damaged. At the present, the ecological problems become acute, such as the poor environmental carrying capacity, heavy pollution, dried-up river, and degradation of ecological function. All these prevent the natural-economical-social system in BTH development. However, most of the eco-restoration studies considered only the river itself, while few studies considered the multi-factors to make the sustainable restoration countermeasures. In this article, we summarize the progress in the related topics including the hydrological environment, the vegetation, the condition of bank, the ecosystem function and health, the ecological service value, and the eco-restoration in Yongding River basin. Then, the main existing problems related with the river, water surroundings, vegetation, and soil are analyzed. Finally, we propose the modes for the eco-restoration of the Yongding River, and provide valid scientific suggestion to keep good eco-environment of Yongding River basin.

Effects of gypsum amendment on salinity ion migration in bauxite residue

TIAN Tao, WU Yujun, XUE Shengguo, HUANG Ling, JIANG Jun, ZHU Feng

2019, 36 (4): 521-529. DOI: 10.7523/j.issn.2095-6134.2019.04.011

Abstract ( 314 ) PDF (KB) ( 7 )

Bauxite residue is an alkaline waste byproduct generated by the extraction of alumina from bauxite, with strong alkalinity and high salinity. Disposal of bauxite residue (red mud) became an increasing concern to the sustainable development of the alumina industry. A leaching column experiment was conducted to study the effects of different treatments (G0:no gypsum, G2:2% gypsum, G4:4% gypsum) on migration and distribution of salt in bauxite residue. The results are given as follows. Compared with the control group, gypsum led to increases of the initial permeation rate, the stable permeability rate, and average permeation in water leaching by 31%-36%,16%-33%, and 9.3%-35%, respectively. The pH ranges of G0, G2, and G4 in water leaching are 8.3-9.4, 8.8-10.0, and 9.0-9.8, respectively. The EC values of G0, G2, and G4 in water leaching are 1.0-4.0, 5.8-7.2, and 5.2-7.5 mS·cm^-1, respectively. Addition of gypsum in bauxite residue is beneficial to the leaching of Na⁺, K⁺, and CO₃^2-. This study provides a scientific basis for the control and prevention of salinity and the soil formation of bauxite residue.

Effects of ameliorants on aggregate stability of bauxite residue

WANG Qiongli, YE Yuzhen, XUE Shengguo, JIANG Jun, ZHU Feng, TIAN Tao

2019, 36 (4): 530-536. DOI: 10.7523/j.issn.2095-6134.2019.04.012

Abstract ( 307 ) PDF (KB) ( 8 )

Bauxite residue is a highly alkaline waste produced during the production of alumina and there is no economical and effective disposal strategy at the present. In this study, gypsum and vermicompost were selected as the ameliorants to investigate their effects on aggregate stability of bauxite residue in the laboratory incubation experiments with different incubation periods. After 60 d incubation, 2% (w/w) gypsum addition reduced the pH from 10.54 to 8.75, whilst 8% (w/w) vermicompost addition increased organic carbon content (TOC) from 3.54 g/kg to 14.31 g/kg. After 180 d incubation, additions of gypsum, vermicompost, and the combination increased the contents of water-stable aggregates from 12.04% to 23.49%, 29.24%, and 33.94%, increased the mean weight diameters (MWD) from 0.15 mm to 0.26, 0.30, and 0.34 mm, and decreased the erodibility factors (K) from 0.36 to 0.31, 0.30, and 0.29, respectively. This study demonstrated that gypsum and vermicompost amendments stimulate water-stable aggregate formation and improve aggregate stability of bauxite residue. Effectiveness of the ameliorants on aggregate stability of bauxite residue decreased in the order:the combination > vermicompost > gypsum. The results provide scientific information for soil formation and large-scale disposal of bauxite residue.

Quality assessment of water and sediment in Duliujianhe River

TANG Yongjie, XIA Jingye, CHEN Yajuan, DAI Zheng, CAI Shubo, LIU Chunguang

2019, 36 (4): 537-544. DOI: 10.7523/j.issn.2095-6134.2019.04.013

Abstract ( 375 ) PDF (KB) ( 1 )

Based on the investigation data of water quality and sediment quality of Duliujianhe River and its major tributaries in 2016, single-factor assessment method, composite-index assessment method, and modified Carlson trophic state index method were used to assess the environmental quality of water and surface sediment of Duliujianhe River and its major tributaries. The results show that the water quality of Duliujianhe River was bad and was worse than Grade V (GB 3838-2002). The heavily-polluted tributaries included Xidawa Drainage River, Chentaizi Drainage River, and Shimihe River. The main pollutants were total nitrogen (TN), ammonia nitrogen (NH₃-N), and chemical oxygen demand (COD). Eutrophication occurred in the whole river and 67% of the sampling sites were heavily eutrophic. Based on the results of the single-factor assessment method, the surface sediments were heavily contaminated and the major pollutants were nitrogen, phosphorus, chromium, copper, and nickel.

Resuscitation of aerobic denitrifying bacteria in the VBNC state and their nitrogen conversion capacity

XU Luning, WANG Yuyang, XUE Binbing, MEI Rongwu, ZHANG Yu, DING Linxian, SU Xiaomei

2019, 36 (4): 545-551. DOI: 10.7523/j.issn.2095-6134.2019.04.014

Abstract ( 376 ) PDF (KB) ( 2 )

At the present,the biological treatment of high ammonium nitrogen wastewater has attracted much attention because of its environmental friendly characteristics and high efficiency. Most of strains can not be excavated due to entry into a viable but non-culturable (VBNC) state. The resuscitation of VBNC strains is important for biological treatment of wastewater with high ammonium nitrogen. In this study,VBNC strain was cultured in high ammonium nitrogen wastewater by resuscitation-promoting factors (Rpf) resuscitation,and its homology was analyzed by 16S rRNA gene sequencing. The isolated strains,which were originally in the VBNC state, were further conducted to investigate the aerobic denitrification capacities with the help of the analyses of nitrate, nitrite, total nitrogen, and ammonium nitrogen. The results showed that the strains belonged to Gordonia and Pseudomonas, among which the aerobic denitrification ability of strain ZYR51 was the highest. This study provides a new method for excavation of VBNC bacteria with aerobic denitrifying properties and a new way for screening efficient strains in the treatment of ammonium nitrogen wastewater.

Dissipation dynamics and risk assessment of three pesticides in broccoli under greenhouse and open field conditions

SUN Caixia, XU Mingfei, DAI Fen, ZHENG Weiran, YU Guoguang, ZHAO Xueping

2019, 36 (4): 552-559. DOI: 10.7523/j.issn.2095-6134.2019.04.015

Abstract ( 356 ) PDF (KB) ( 2 )

Broccoli is a typical vegetable for both domestic consumption and exportation. Chlorpyrifos, phoxim, and indoxacarb are 3 pesticides used widely in plant protection. Field experiments were conducted to study the residues and dissipation dynamics of these pesticides in broccoli flowers and leaves, with 1 time and 1.5 times the recommended use dosage, under greenhouse and open field conditions. The samples were treated by the QuEChERS method and the liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. The method validation results showed that, with the concentrations of 0.02, 0.2, and 1 mg/kg, the recovery rates of chlorpyrifos, phoxim, and indoxacarb were 85.8%-101.0%,90.8%-105.3%, and 86.1%-107.5%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were 0.006 and 0.01 mg/kg, respectively. The results showed that the method meets the detection requirement. The dissipation results showed that, in broccoli flowers, the half-lives were 5.53-7.20 d for chlorpyrifos, 3.55-3.92 d for phoxim, and 6.11-7.73 d for indoxacarb. While, in broccoli leaves, the half-lives were 4.33-6.93 d for chlorpyrifos, 3.85-5.77 d for phoxim, and 3.85-5.33 d for indoxacarb. In soil, the half-lives were 23.1-34.6 d for chlorpyrifos, 23.1-34.6 d for phoxim, and 17.3-23.1 d for indoxacarb. The final residues showed that, for these 3 pesticides, the residues in broccoli leaves were higher than these in broccoli flowers. With the trial application dosage, the final residues of chlorpyrifos and indoxacarb were lower than the MRLs in EU, Japan, and CAC. While for phoxim, the final residues with higher application dosage exceeded the MRLs.

Hyperspectral monitoring of soil contaminated by heavy metals

CHEN Gongwei, ZHAO Siying, NI Caiying

2019, 36 (4): 560-566. DOI: 10.7523/j.issn.2095-6134.2019.04.016

Abstract ( 386 ) PDF (KB) ( 1 )

To explore the correlation of spectrum parameters of rice with soil heavy metal pollution, the paddy field measurements in Guixi County of Jiangxi Province and the remote sensing spectral analyses were finished in this study. The results showed a positive correlation between heavy metals' contents (Cu, Pb, Zn, and Cd) in rice and in soil, but a negative correlation between heavy metals and chlorophyll content (SPAD value) of rice. Among the four polluted metals Cd had the highest correlated coefficients, and the rice SPAD value had a significant correlation with the remote sensing spectral characteristic parameters such as blue valley location, blue valley depth, red valley location, and red edge peak value only when the Cd pollution mentioned. Therefore, in the study area, the heavy metal Cd in paddy soil could be effectively monitored by the remote sensing spectroscopy.

Adsorption interaction between cytochrome c and fullerene derivatives

ZHANG Yujie, LI Xiaoyi

2019, 36 (4): 567-569. DOI: 10.7523/j.issn.2095-6134.2019.04.017

Abstract ( 315 ) PDF (KB) ( 5 )

Cytochrome c is an electron-rich protein that widely exists in cell mitochondria. In the interaction process with nanomaterials, it generates free radicals and amplifies the biological toxicity of nanomaterials. In order to understand its interaction with nanomaterials, molecular dynamics simulations are conducted on cytochrome c and fullerene derivative systems including fullerene trimalonate and fullerol. We have studied the interaction energy, the mean radius of gyration, the number of contacting atoms, and the distance from the Fe atom in cytochrome c to the mass center of the fullerene derivative. As a result, mechanism of the interaction between cytochrome c and fullerene derivatives is revealed at the atomic dimension.

Study on control strategy of active rehabilitation training for upper limb rehabilitation robots

LIU Peng, GE Xiaoqing, LI Yu, ZHAO Jiaxin

2019, 36 (4): 570-576. DOI: 10.7523/j.issn.2095-6134.2019.04.018

Abstract ( 396 ) PDF (KB) ( 2 )

In recent years, the upper limb injuries increased year by year due to the stroke and traffic accidents, which caused the demanding for rehabilitation equipment. In order to meet the actual needs, we developed a four-degrees-of-freedom robot which is driven by pneumatic actuator muscle (shoulder joint adduction/in show (passive), precursor/reach, elbow flexion, and wrist flexion). First, the structure of upper limb rehabilitation robot was designed, and pneumatic artificial muscle was used as the driver of elbow joint and wrist joint. Then, for the upper limb rehabilitation robot designed in this studg, two kinds of control under active rehabilitation training were designed. Finally, the effectiveness of the control strategy is verified through the wear tests, which shows the practical value of the rehabilitation robot.

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