Cao H.,Northwest Normal University |
Cao H.,Chizhou College
Advances in Mathematical Physics | Year: 2017
We propose a new method applying matrix theory to analyse the instability conditions of unique homogeneous coexistent state of multispecies host-parasitoid systems. We consider the eigenvalues of linearized operator of systems, and by dimensionality reduction, this infinite dimensional eigenproblem will be reduced to a parametrized finite dimensional eigenproblem, thereby applying combinatorial matrix theory to analyse the linear instability of such constant steady-state. © 2017 Huaihuo Cao.
Chen P.,Tongji University |
Chen P.,Chizhou College |
Wu Q.-S.,Tongji University |
Ding Y.-P.,Shanghai University |
And 3 more authors.
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2010
In order to improve both safety and efficacy of cancer chemotherapy of titanocene dichloride and overcome the shortcomings such as instability and short half-life in the human body, we report a controlled release system of titanocene dichloride by electrospun fiber and its in vitro antitumor activity against human lung tumor spca-1 cells. The system was developed by electrospinning. The release profiles of titanocene dichloride in PBS were researched by UV-Vis spectrophotometer. In vitro antitumor activities of the fibers were examined by MTT method. Titanocene dichloride was well incorporated in biodegradable poly(l-lactic acid) fibers. XRD results suggest that titanocene dichloride exists in the amorphous form in the fibers. The controlled release of titanocene dichloride can be gained for long time. MTT showed actual titanocene dichloride content 40, 80, 160 and 240. mg/L from the fibers mat, cell growth inhibition rates of 11.2%, 22.1%, 44.2% and 68.2% were achieved, respectively. The titanocene dichloride released has obvious inhibition effect against lung tumor cells. The system has an effect of controlled release of titanocene dichloride and may be used as an implantable anticancer drug in clinical applications in the future. © 2010 Elsevier B.V.
Liu L.-B.,Chizhou College |
Liu H.-W.,Guangxi University for Nationalities
International Journal of Computer Mathematics | Year: 2011
In this paper, a numerical method is developed to solve an N-carrier system with Neumann boundary conditions. First, we apply the compact finite difference scheme of fourth order for discretizing spatial derivatives at the interior points. Then, we develop a new combined compact finite difference scheme for the boundary, which also has fourth-order accuracy. Lastly, by using a Padé approximation method for the resulting linear system of ordinary differential equations, a new compact finite difference scheme is obtained. The present scheme has second-order accuracy in time direction and fourth-order accuracy in space direction. It is shown that the scheme is unconditionally stable. The present scheme is tested by two numerical examples, which show that the convergence rate with respect to the spatial variable from the new scheme is higher and the solution is much more accurate when compared with those obtained by using other previous methods. © 2011 Copyright Taylor and Francis Group, LLC.
Zhang G.-Q.,Chizhou College
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2014
The monocrystalline silicon material were cut by brazed diamond wire saw under the machining condition of constant feed rate. The influence of cutting parameters on the cutting force and surface roughness were discussed. Cutting force model for the brazed diamond wire saw in cutting the monocrystalline silicon material was established, and the normal force formula at the angle of the cross section of the wire saw was explored. Based on the indentation fracture mechanics performance of the monocrystalline silicon material, the material removal mechanism during it being cut with the brazed diamond wire saw was discussed. Experimental results show that the normal force gradually reduces from the maximum to the zero value. At any cutting parameters, there existes a brittle-plastic transition angle at the cross section of the wire saw and its value determines the material removal mode of the surface of the workpiece. ©, 2014, Chinese Ceramic Society. All right reserved.
Xiaoying S.,Nanjing University of Science and Technology |
Huanyan Q.,Nanjing University of Science and Technology |
Haisheng H.,Chizhou College
International Journal of Digital Content Technology and its Applications | Year: 2011
Wireless networked control system (WNCS) is given profound attention because of dynamic, flexibility and inexpensiveness. However, it is difficult to use a single simulator to simulate a WNCS which is a hybrid system. A co-simulation framework based on OPNET, Matlab and C++ is presented to capture both the system dynamics and communication events and depict the real WNCS accurately. MATLAB is good for simulating the mathematical modeling and feedback control, while OPNET is apt at simulating the WLAN communication behavior. The co-simulation framework can help WNCS designer understand and improve the performance of the WNCS.
Hu C.,Chizhou college
Applied Mechanics and Materials | Year: 2012
Surface characteristics of the regular polygon contour parts and turning process,including tool movement characteristics,feed speed and feed acceleration, is analyzed with the harmonic analysis principle when cutting the parts. Using MATLAB to draw the displacement, velocity and acceleration variations chart of polygon workpiece turning. © (2012) Trans Tech Publications, Switzerland.
Pan G.,Nanjing Agricultural University |
Xu X.,Nanjing Agricultural University |
Xu X.,Chizhou College |
Smith P.,University of Aberdeen |
And 2 more authors.
Agriculture, Ecosystems and Environment | Year: 2010
Soil C sequestration in cropland could play an important role in mitigating the rapidly increasing CO2 emissions in China. Many efforts had been dedicated to estimating the potential for C sequestration in croplands. Potential increases in SOC in China's croplands had been recently evaluated using inventory-up-scaling simulation and crop-soil C process-based modeling. In this study, data of SOC change at monitoring sites from croplands across mainland China were collected from publications available from 1985 to 2006 to perform a statistical analysis. The data set comprises 1081 observations (404 from rice paddies, RPs and 677 from dry croplands, DCs). Frequency analysis indicates that over 70% of observations show an increase in SOC, which is higher among RPs than DCs. To quantify SOC dynamics, a Relative Annual Change Index in g kg-1 year-1 (RAC, g kg-1 year-1) is defined and calculated using the initial and final SOC values for the duration of monitored observations. RAC values ranged from -0.806 to 0.963 g kg-1 year-1 for DCs and from -0.597 to 0.959 g kg-1 year-1 for RPs, respectively. From this data, the average is estimated to be 0.056 ± 0.200 g kg-1 year-1 for DCs, and 0.110 ± 0.244 g kg-1 year-1 for RPs, with an overall estimate for China's croplands, with RPs and DCs combined, of 0.076 ± 0.219 g kg-1 year-1. A mean increase in topsoil C (0-20 cm) stock of China's croplands was estimated to be 25.5 Tg C year-1 (8 Tg C year-1 in RPs and 17.5 Tg C year-1 in DCs) between 1985 and 2006, with a total topsoil C stock increase of 0.64 Pg C over the whole period. The annual stock increase may offset ∼20%, on average, of the total CO2 emissions of China for 1994. This study suggests an important role of China's croplands, especially rice paddies, for C sequestration to mitigate climate change. © 2009 Elsevier B.V. All rights reserved.
Chen J.B.,Chizhou College
Advanced Materials Research | Year: 2014
The PEEK/PEI/PES plastic alloys were processed by twin-screw extruder at 370°C separately with four mass ratios of 70/30/0, 70/25/5, 65/30/5, 60/30/10. The solvent resistance were investigated by experiments, their results showed that the concentrated H2SO4 resistance of alloy plates had been improved by alloying in 6h, the acetone resistance of mass ratio of 70/25/5 is preferably, increasing the content of PES, the acetone resistance becomes relatively stable, in addition, the chloroform and N, N-dimethyl formamide resistance of mass ratio of 70/25/5 is also preferably, and the polarity of the reagent has a limit influence on solvent resistance of plastics alloy materials. © (2014) Trans Tech Publications, Switzerland.
Zhang L.,Chizhou College
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014
The process of urbanization is closely related to land use. When the level of urbanization evolves from primary level to senior level, land-intensive use of small towns will be continuously upgraded along with the increase of adjustment and optimization of industrial structure, urban high-rise buildings, and strengthening of national protection policy cultivated land, which is when the demand of cultivated land exhibits a decreasing trend in the process of transition of urbanization from the primary stage to the advanced stage, similar to the law of diminishing marginal returns of economics. Therefore, there is the effect of minimum ultimate moment of urbanization on cultivated land in theory. Exploring the ultimate moment has an important guiding significance for the policies of cultivated land under the evolutionary background of compilation of land-use planning and formulation of urbanization development. Taking Anhui Province as an example, a total of 18 indices, such as the proportion of urban permanent population in total population, are selected to establish the evaluation system of urbanization comprehensive level from four dimensions of population, space, economy, and social life, of which the composite index is calculated by the entropy weighting method. The Logarithmic Mean Divisia Index (LMDI) decomposition model is used to calculate the reduced cropland share due to urbanization. Based on economic marginal theory, the least-squares regression analysis method is adopted to construct the measurement model of marginal cropland change rate due to urbanization. With the aid of EXCEL software through scatter diagrams with trend lines, the optimal goodness of fit is applied to obtain the curves and the derivative method of advanced mathematic extremum, so as to estimate the extreme moment of urbanization evolution with the least impact on cropland. The results show that: the urbanization composite index of Anhui Province rose from 0.0319 in 1996 to 0.9945 in 2012, of which the increase range is faster than that of population urbanization level. Urbanization leads to cropland reduction declining after 2002, in line with the diminishing law of marginal effect in economics. The marginal cropland change rate due to urbanization in Anhui Province was reduced from 1 292 517.63 in 2002- 2003 to 7 430.35 in 2011-2012, presenting an overall downward trend; the fitting curve of marginal cropland change rate is a U-shaped parabola with an upward opening. When the urbanization comprehensive index is 7.325, i.e. in 2022-2023, the urbanization will have the least effect on cropland, while before 2023, the contradiction between urbanization and cropland protection will be more prominent in Anhui Province. Based on the results of the study, it is reasonable to arrange scale, structure, layout, and timing from the scientific establishment of the urbanization development of land use planning of urban construction land. Optimization and upgrading of industrial structure are used to promote intensive use of urban land. Various policies, laws, and regulations are strictly implemented in the state protection of cultivated land. Policy suggestions are put forward in strictly maintaining land gate, strengthening land inspection, and other aspects. The research results not only provide references for Anhui Province to scientifically formulate land use planning and coordinate the urbanization evolution and cropland protection policy, but also for other similar research. ©, 2014, Chinese Society of Agricultural Engineering. All right reserved.
Zhang L.,Chizhou College |
Chen F.,Chizhou College
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014
Accelerating urbanization is a major development strategy proposed by the 18th Communist Party of China (CPC) National Congress. The prospect for the influence of China's future urbanization evolution on cultivated land relates to the realization of a red line target of cultivated land protection and food safety. To reveal the evolution of China's urbanization impact on cultivated land, the author explores the problem based on a logistic model. Using SPSS software and China's urbanization level data from 1978 to 2011, the goodness-of-fit maximum estimation method of regression curve was employed to estimate the saturation value of China's urbanization level and the Logistic model of describing China's urbanization evolution was structured. Accordingly, the development level of China's future urbanization was predicted. Based on a STRIPAT model and relevant data of China 's eco-social development from 1996 to 2011, SPSS software was combined with a partial least squares regression method to reveal the marginal contributions of urbanization process, population, economic development level, and technical factors on cultivated land change. According to China's future urbanization evolutionary trend and the marginal influence of urbanization on cultivated land, the influence of China's future urbanization on cultivated land was measured. The results are shown as the followings: 1) The saturation value of China's urbanization level is 83%. 2) China's urbanization level will reach 57.68% and 65.73% in 2020 and 2030 respectively. Before 2020, the annual average growth rate of urbanization will be 0.97 percent point, and from 2020 to 2030, that will be 0.81percent point. 3) The marginal elasticity coefficient of urbanization, population, economic development level, and technological factors on cultivated land change will be -0.007391, -0.007133, -0.009343, and -0.002952 respectively. 4) From 2012 to 2020, urbanization evolution will lead to a net area reduction of cultivated land of 13.81×104 hm2 with an annual average reduction of 1.53×104 hm2. From 2020 to 2030, that will be 10.87×104 hm2 with an annual average reduction of 1.09×104 hm2. Based on the results of the above, several measures should be implemented including focusing on the quality of urbanization with a moderate grasp on the speed of urbanization, scientifically preparing the annual land supply planning, adopting a differentiated land supply strategy, abandoning the wrong philosophy of land finance, strictly implementing national protection policies foe cultivated land, rigorously controlling real estate land and low-level or repeated production land; severely punishing violations of land use, and strengthening the policy recommendations on land supervision. The results can provide a reference for management to grasp the moderate urbanization pace and rhythm, scientifically prepare a land supply plan, and formulate cultivated land protection policies, as well as offer a method of reference for similar studies on a provincial scale.