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Search Results: 1 - 10 of 156005 matches for " Juan Li "
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Fabrication of Poly(Aspartic Acid)-Nanogold Modified Electrode and Its Application for Simultaneous Determination of Dopamine, Ascorbic Acid, and Uric Acid  [PDF]
Juan Li, Xiaoli Zhang
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.33028
Abstract: A nanostructured polymer film incorporated gold nanoparticles modified electrode was fabricated. The fabrication process involved a previous electropolymerization of aspartic acid and followed by the eletrodeposition of gold nano-particles on the glassy carbon electrode. The resulting poly (aspartic acid)-nanogold modified electrode (PAA- nano-Au/GCE) was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectros-copy (EIS). A higher catalytic activity was obtained to electrocatalytic oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) due to the enhanced peak current and well-defined peak separations compared with three, bare GCE, PAA/GCE and nano-Au/GCE. Simultaneous determination of DA, AA, and UA were studied by voltammetry. The linear range of 5.0 × 10-7 - 1.0 × 10-4 M for DA, 5.0 × 10-6 - 2.0 × 10-3 M for AA and 5.0 × 10-6 - 1.0 × 10-3 M for UA was obtained. The detection limit was calculated for DA, AA and UA as being 6.5 × 10-8 M, 5.6 × 10-7 M and 3.0 × 10-7 M, respectively (S/N = 3). The practical application of the present modified electrode was demonstrated by the determination of DA, AA and UA in calf serum and fetal calf serum samples.
Analysis of Switching Overvoltage in Regional Grid with Small Hydropower Plants  [PDF]
Juan Chen, Haifeng Li
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.59B004
Abstract: Present-day small hydropower plants (SHPs) have a large development potential because of the increasing interest in renewable resources and distributed energy generation, therefore, there are many SHPs in places of China where are rich in water resources. However, it has caused overvoltages in the distribution network, and which is even worse for the switching overvoltage such as isolated network operation, changing power supply path. The simple network model is used to analyze the reasons of the switching overvoltage, and the simulation software DIgSILENT/PowerFactory is used to check out the results of the theoretical analysis.
Existence of solution for a singular elliptic equation with critical Sobolev-Hardy exponents
Juan Li
International Journal of Mathematics and Mathematical Sciences , 2005, DOI: 10.1155/ijmms.2005.3213
Abstract: Via the variational methods, we prove the existence of a nontrivial solution to a singular semilinear elliptic equation with critical Sobolev-Hardy exponent under certain conditions.
Reflected Mean-Field Backward Stochastic Differential Equations. Approximation and Associated Nonlinear PDEs
Juan Li
Mathematics , 2012,
Abstract: Mathematical mean-field approaches have been used in many fields, not only in Physics and Chemistry, but also recently in Finance, Economics, and Game Theory. In this paper we will study a new special mean-field problem in a purely probabilistic method, to characterize its limit which is the solution of mean-field backward stochastic differential equations (BSDEs) with reflections. On the other hand, we will prove that this type of reflected mean-field BSDEs can also be obtained as the limit equation of the mean-field BSDEs by penalization method. Finally, we give the probabilistic interpretation of the nonlinear and nonlocal partial differential equations with the obstacles by the solutions of reflected mean-field BSDEs.
Note on stochastic control problems related with general fully coupled forward-backward stochastic differential equations
Juan Li
Mathematics , 2012,
Abstract: In this paper we study stochastic optimal control problems of general fully coupled forward-backward stochastic differential equations (FBSDEs). In Li and Wei [8] the authors studied two cases of diffusion coefficients $\sigma$ of FSDEs, in one case when $\sigma$\ depends on the control and does not depend on the second component of the solution $(Y, Z)$ of the BSDE, and in the other case $\sigma$ depends on $Z$ and doesn't depend on the control. Here we study the general case when $\sigma$ depends on both $Z$ and the control at the same time. The recursive cost functionals are defined by controlled general fully coupled FBSDEs, then the value functions are given by taking the essential supremum of the cost functionals over all admissible controls. We give the formulation of related generalized Hamilton-Jacobi-Bellman (HJB) equations, and prove the value function is its viscosity solution.
Decentralized Self-Management of Trust for Mobile Ad Hoc Social Networks
Juan Li,Qingrui Li
International Journal of Computer Networks & Communications , 2011,
Abstract: The construction of social networks over mobile devices in the events or at locations has emerged as anew network paradigm. These new mobile social networks enable people to communicate and share theirexperiences without the need to have Internet access and with minimum required infrastructure.However, the functionality and security of such networks would be potentially undermined without aneffective trust management scheme. Although many trust management systems have been proposed, few ofthem can be applied to these new mobile social networks because of the unique network andcommunication characteristics. This paper presents a novel trust management system, termedMobileTrust, to establish decentralized, secure and reliable trust relationships between mobile ad hocsocial network participants. Specifically, the construction of trust models encompasses both scenariosthat users are experienced with the network and users are unacquainted with the environment. The trustmodels cover various important factors of trust relationships in social networks, including the similarityof user profile, reputation, and history of friendship. A set of simulations is conducted to evaluate oursystem deployed in a mobile social network in the presence of dishonest users.
Zero-sum and nonzero-sum differential games without Isaacs condition
Juan Li,Wenqiang Li
Mathematics , 2015,
Abstract: In this paper we study the zero-sum and nonzero-sum differential games with not assuming Isaacs condition. Along with the partition $\pi$ of the time interval $[0,T]$, we choose the suitable random non-anticipative strategy with delay to study our differential games with asymmetric information. Using Fenchel transformation, we prove that the limits of the upper value function $W^\pi$ and lower value function $V^\pi$ coincide when the mesh of partition $\pi$ tends to 0. Moreover, we give a characterization for the Nash equilibrium payoff (NEP, for short) of our nonzero-sum differential games without Isaacs condition, then we prove the existence of the NEP of our games. Finally, by considering all the strategies along with all partitions, we give a new characterization for the value of our zero-sum differential game with asymmetric information under some equivalent Isaacs condition.
A Reputation-Based Multi-Agent Model for Network Resource Selection  [PDF]
Junfeng TIAN, Juan LI, Lidan YANG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.28089
Abstract: Because of the anonymity and openness of online transactions and the richness of network resources, the problems of the credibility of the online trading and the exact selection of network resources have become acute. For this reason, a reputation-based multi-agent model for network resource selection (RMNRS) is presented. The model divides the network into numbers of trust domains. Each domain has one domain-agent and several entity-agents. The model prevents the inconsistency of information that is maintained by differ-ent agents through the periodically communication between the agents. The model enables the consumers to receive responses from agents significantly quicker than that of traditional models, because the global reputation values of service providers and consumers are evaluated and updated dynamically after each transaction. And the model allocates two global reputation values to each entity and takes the recognition value that how much the service provider knows the service into account. In order to make users choose the best matching services and give users with trusted services, the model also takes the similarity between services into account and uses the similarity degree to amend the integration reputation value with harmonic-mean. Finally, the effectiveness and feasibility of this model is illustrated by the experiment.
Heavy Metals’ Spatial Distribution Characteristics in a Copper Mining Area of Zhejiang Province  [PDF]
Hua Sun, Juan Li, Xiaojun Mao
Journal of Geographic Information System (JGIS) , 2012, DOI: 10.4236/jgis.2012.41007
Abstract: The spatial distribution characteristics of six heavy metals and metalloid in soil of Zhuji Lipu copper mining area, Zhejiang Province, was studied by using geostatistics approaches combined with GIS. These elements included Pb, As, Cr, Cu, Zn and Ni. The statistical analyses showed that concentrations of these elements were lognormal distribution. Concentrations of Pb, As, Cu, Zn and Ni were strongly correlated with each other indicating that these elements in soils may be from the same pollution source. However, accumulation of Cr was unique with its geometric mean being close to that in the control soil. This indicates that Cr content was mainly influenced by soil factors. The Kriging method was applied to estimate the unobserved points. The Kriging interpolation maps reflected significant spatial distribution of these elements as influenced by both pollution and geological factors. The present study indicated that GIS based geostatistics method could accurately analyze the spatial variation of heavy metals and metalloid in the mining area. Overall, higher concentrations of heavy metals and metalloid were found in the center of both the north and south sides. The content of copper in the south was significantly higher than that in the north due to paddy field land uses. In addition, the terrain of four terraces tilted to the center and the broad irrigation accident occurred in the 4th trench in the south of sampling area were also contributed to the higher concentrations of these elements.
Research on Modes of Cargo Ro-Ro, Drop and Pull Transport in Land-Sea Transportation Channel between Shandong and Liaoning  [PDF]
Yongsheng Liu, Yu Li, Juan Chen
Journal of Service Science and Management (JSSM) , 2015, DOI: 10.4236/jssm.2015.82025
Abstract: In order to accelerate national industrial upgrading of transportation and deepen the development of logistics industry, it is imperative to construct the land-sea transportation channel between Shandong and Liaoning provinces. Taking practical situations of the two places into account, the paper aims to investigate the application of M to N mode in the process of cargo roll on-roll off, drop and pull transport and then elaborate the site selection issue of drop and pull centers from the perspective of P-median model. Meanwhile, the paper proposes to adopt “south bridging-north rolling” concept to build a brand new transportation channel which combines the cross-sea bridge with ro-ro ferry concerning the natural conditions in Bohai Bay. Corresponding solution to each project will be put forward at last.
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