Influence of urbanization on the surface water quality in Guangzhou,China

The urbanization process is a trend occurring inevitably in the historical development. This paper reviews the progress of the urbanization in Guangzhou and focuses on the change of water quality in the Guangzhou reach of the Pearl River. 8 kinds of main pollutant parameters were collected from 9 important sections in the Guangzhou reach of the Pearl River from 1986 to 2000 and the water quality change was analyzed per time and space. The study concludes that the surface water quality of Guangzhou reflects ...     

Screening and denitrification characteristics of a slight halophilic heterotrophic nitrobacteria

A slight halophilic heterotrophic nitrobacteria named gs1 was separated from the matured activated sludge. According to the morphological observation,physiological biochemical tests and sequence analysis of the 16S rDNA,strain gs1 was identified to be as Pseudomonas sp. Sodium acetate and ammonium chloride were used as carbon and nitrogen sources,respectively,to investi-gate the characteristics of the bacterium. When cultured for 24 h under aerobic conditions,with the removal rates of the NH4+-N and COD being 82.2% and 74.73%,respectively,strain gs1 will have a nitrification function of producing NO2--N. When cultured for 24 h under aerobic conditions in nitrite medium,the removal rate of the NO2--N became 100%,and when cultured for 24 h under aerobic conditions in nitrate medium,the removal rate of the NO3--N became 97%. The result shows that this strain functions for either nitrification or denitrification,i.e.,it can complete the full process of biological deoxidation.     

HLA-B*6701 as a subtype performing post-selected marking gene for cervical cancer

A method of sequence-based typing (SBT) has been adopted to assort types of exons 2 and 3, which have the most polymorphism, of HLA-B locus of the Tujia nation group in Hubei province. The correlation among the HLA-B alleles, human papillomavirus (HPV) infection and cervical cancer risk has also been investigated. Under the condition of resident location and age, race unified, 100 specimens of cancer patients were sampled as a case group, of which 86 were HPV positive and were screened for HLA-B alleles; while 187 specimens were taken from healthy people, of which 92 were HPV negative as a control group. The result shows that by comparing the above mentioned 86 HPV positive cervical cancer group and 92 HPV negative normal group, it was concluded that HLA-B*6701 was only found in the cervical cancer group (p < 0.034), which shows that HLA-B*6701 can be used as an important candidate biological marking gene for generation of cervical cancer in Wufeng county of Hubei province.     

Measurement study on wind characteristics of Typhoon Kalmaegi on the sutong bridge

The Sutong Bridge, a cable-stayed located in the southeast coastal area of China, is vulnerable to the Pacific typhoons. From the data measured by two 3D ultrasonic anemometers at the height of 76 m and 306 m, the wind characteristics (including 10-minute mean wind speed and direction, turbulence intensity and gust factor, power spectral density and integral scale of turbulence) of Typhoon Kalmaegi are analyzed The comparison of 10-minute mean wind velocity from the two anemometers validates the reliability...     

Some functions with low differential uniformity

We study the functions with low differential uniformity, and concentrates mainly on the properties of perfect nonlinear (PN) functions, including the properties of the derivative of the components of those functions. Some sufficient and necessary conditions have been explored to judge when a function is a PN function. These conditions may be useful in constructing new PN functions. We also construct some functions with differential 4-uniformity that have rarely been studied in the literature. Some of the constructed functions with differential 4-uniformity have high nonlinearity as well. Finally, a class of functions with differential 4-uniformity which are not extended affine equivalent to any power functions are constructed.     

Generalized ridge estimation of a semiparametric regression model

We considered the following semiparametric regres-sion model yi = X iT β+ s ( t i ) + ei (i =1,2,,n). First,the general-ized ridge estimators of both parameters and non-parameters are given without a restrained design matrix. Second,the generalized ridge estimator will be compared with the penalized least squares estimator under a mean squares error,and some conditions in which the former excels the latter are given. Finally,the validity and feasibility of the method is illustrated by a simulation example.     

Congruence permutable Kleene-Stone algebras

A Kleene-Stone algebra is a bounded distributive lattice with two unary operations that make it a Kleene and a Stone algebra. In this paper, we study the properties of the prime ideals in a Kleene-Stone algebra and characterize the class of Kleene-Stone algebras that are congruence permutable by means of the dual space of a Kleene-Stone algebra and then show that a finite Kleene-Stone algebra is congruence permutable if and only if it is isomorphic to a direct product of finitely many simple algebras.     

A dynamic ID-based authenticated group key exchange protocol without pairings

So far, most of the proposed group key exchange (GKE) protocols do not consider the attack when the adversary reveals the parties’ephemeral private keys without their long-term private keys, so these GKE protocols are insecure on this attack. In this paper, for resisting above attack, we propose a dynamic authenticated group key exchange (AGKE) protocol in the ID-based setting. Different from previous ID-based protocols, our protocol does not utilize bilinear pairings, which makes it more efficient. At last, we analyze the security of the protocol in the eCK (enhanced Canetti-Krawczyk) security model.     

A line search filter secant method for nonlinear equality constrained optimization

<正> This paper formulates and analyzes a line search method for general nonlinear equalityconstrained optimization based on filter methods for step acceptance and secant methods for searchdirection.The feature of the new algorithm is that the secant algorithm is used to produce a searchdirection,a backtracking line search procedure is used to generate step size,some filtered rules areused to determine step acceptance,second order correction technique is used to reduce infeasibility andovercome the Maratos effect.Global convergence properties of this method are analyzed:under mildassumptions it is showed that every limit point of the sequence of iterates generated by the algorithmis feasible,and that there exists at least one limit point that is a stationary point for the problem.Moreover,it is also established that the Maratos effect can be overcome in our new approach by addingsecond order correction steps so that fast local superlinear convergence to a second order sufficient localsolution is achieved.Finally,the results of numerical experiments are reported to show the effectivenessof the line search filter secant method.     

Convergence rates of Markov chain approximation methods for controlled diffusions with stopping

<正> This work is concerned with rates of convergence of numerical methods using Markov chainapproximation for controlled diffusions with stopping (the first exit time from a bounded region).In lieuof considering the associated finite difference schemes for Hamilton-Jacobi-Bellman (HJB) equations,a purely probabilistic approach is used.There is an added difficulty due to the boundary condition,which requires the continuity of the first exit time with respect to the discrete parameter.To prove theconvergence of the algorithm by Markov chain approximation method,a tangency problem might arise.A common approach uses certain conditions to avoid the tangency problem.Here,by modifying thevalue function,it is demonstrated that the tangency problem will not arise in the sense of convergencein probability and in L~1.In addition,controlled diffusions with a discount factor is also treated.