Existence and uniqueness of a class of double pyramidal central configurations in six-body problems

Under the necessary conditions for a double pyramidal central configuration with a diamond base to exist in the real number space, the existence and uniqueness of such configurations were studied by employing combinedly the algebraic method and numerical calculation. It is found that there exists a planar curl triangle region G in a square Q such that any point in G and given by the ratio of the two diagonal lengths of the diamond base and the ratio of one diagonal length of the base to the height of the double pyramid configuration determines a unique double pyramid central configuration, while all points in Q-G have noreferance to any central configuration.     

MEASUREMENT OF THE DIELECTRIC PROPERTIES OF BIOLOGICAL TISSUE

An open-ended coaxial line reflection method especially suitable for meas-uring the dielectric properties of biological tissue in vivo is described.This method offersthe advantage of not requiring any special preparation of the samples to be measured but aclose contact with the open end of a coaxial line.It is,therefore,very convenient to acquirea large number of measurement data in broad band rapidly.The method may also be usedto measure the properties of other substances.The measuring system consists of a networkanalyzer controlled by a microcomputer and calibrated by using ANA procedure to elimi-hate the influnce of error network introduced by the adapter,some connectors,etc.In or-der to reach higher accuracy,the iterative method is used to determine the parameters ofthe equivalent circuit.Measurements of permeativities of some living tissues have been per-formed in the frequency band of 0.5-2GHz.Compared with the results known in somepapers,the validity of this method has been confirmed.The difference in dielectric proper-ties between living and dead tissues,and the tissue permeativites(ε)versus frequency andduration of measurement after death have also been measured.     

图的整数值控制函数

For an arbitrary subset P of the reals, a function f ： V →P is defined to be a P-dominating function of a graph G = （V, E） if the sum of its function values over any closed neighbourhood is at least 1. That is, for every v ∈ V, f（N[v]） ≥ 1. The definition of total P-dominating function is obtained by simply changing ‘closed＇ neighborhood N[v] in the definition of P-dominating function to ‘open＇ neighborhood N（v）. The （total） P-domination number of a graph G is defined to be the infimum of weight w（f） = ∑v ∈ V f（v） taken over all （total） P-dominating function f. Similarly, the P-edge and P-star dominating functions can be defined. In this paper we survey some recent progress on the topic of dominating functions in graph theory. Especially, we are interested in P-, P-edge and P-star dominating functions of graphs with integer values.     

图的整数值控制函数

For an arbitrary subset P of the reals,a function f:V→P is defined to be a P-dominating function of a graph G=(V,E) if the sum of its function values over any closed neighbourhood is at least 1.That is,for every v∈V, f(N[v])≥1.The definition of total P-dominating function is obtained by simply changing‘closed’neighborhood N[v]in the definition of P-dominating function to‘open’neighborhood N(v).The (total) P-domination number of a graph G is defined to be the infimum of weight w(f) =∑_(v∈V)f(v) taken over all (total) P-dominating function f.Similarly,the P-edge and P-star dominating functions can be defined.In this paper we survey some recent progress oil the topic of dominating functions in graph theory.Especially,we are interested in P-,P-edge and P-star dominating functions of graphs with integer values.     

Global Temperatures Fourth Highest on Record

Find a number consisting of 9 digits in which each of the digits from 1 to 9 appears only once. This number should satisfy the following requirements： a. The number should be divisible by 9. b. If the most right digit is removed, the remainingnumber should be divisible by 8.     

“TAKE”之12短语

The verb take is extremely useful. It can be used in a number of expressions. Here are 12.Learning Expressions The best way to learn any words or expressions is by seeing or hearing them in context when you＇ re reading or listening to English. Make a note of any words or expressions that you like （or want to learn） and write these down in sentences. Remember, always record language in phrases or sentences--never as individual words. You should also practise using the words or expressions as often as you can： in conversation, on the phone, in e-mails, etc.     

Application of RBF Neural Network in OptimizingMachining Parameters

In machining processes, errors of rough in dimension, shape and location lead to changes in processing quantity, and the material of a workpiece may not be uniform. For these reasons, cutting force changes in machining, making the machining system deformable. Consequently errors in workpieces may occur. This is called the error reflection phenomenon. Generally, such errors can be reduced through repeated processing while using appropriate processing quantity in each processing based on operator‘s experience.According to the theory of error reflection, the error reflection coefficient indicates the extent to which errors of rough influence errors of workpieces. It is related to several factors such as machining condition, hardness of the workpiece, etc. This non-linear relation cannot be worked out using any formula. RBF neural network can approximate a non-linear function within any precision and be trained fast. In this paper, non-linear mapping ability of a fuzzy-neural network is utilized to approximate the non-linear relation. After training of the network with swatch collection obtained in experiments, an appropriate output can be obtained when an input is given. In this way, one can get the required number of processing and the processing quantity each time from the machining condition. Angular rigidity of a machining system,hardness of workpiece, etc., can be input in a form of fuzzy values. Feasibility in solving error reflection and optimizing machining parameters with a RBF neural network is verified by a simulation test with MATLAB.     

STUDY ON THE INTERRELATION BETWEEN THE FOREIGN ELEMENTS AND THE NATIVE ELEMENT IN ENGLISH——English Borrowings from Chinese

English,as a cosmopolitan language,is one of the most colorful languages in theworld.Itis rather open to the foreign words.Considering its shorthistory of1 50 0 years,it is surprising that English has absorbed a great number of useful words and expressionsof almostevery language all over the world.In a survey of the1 0 0 0 mostfrequently usedwords in English,it was found that 38. 3% were borrowed from other languages( Crabtree,1 991 ) . The English borrowings are not only from French,Latin,…     

WAPN: a distributed wormhole attack detection approach for wireless sensor networks

As the applications of wireless sensor networks （WSNs） diversify, providing secure communication is emerging as a critical requirement. In this paper, we investigate the detection of wormhole attack, a serious security issue for WSNs. Wormhole attack is difficult to detect and prevent, as it can work without compromising sensor nodes or breaching the encryption key. We present a wormhole attack detection approach based on the probability distribution of the neighboring-node-number, WAPN, which helps the sensor nodes to judge distributively whether a wormhole attack is taking place and whether they are in the influencing area of the attack. WAPN can be easily implemented in resource-constrained WSNs without any additional requirements such as node localization, tight synchronization, or directional antennas. WAPN uses the neighboring-node-number as the judging criterion, since a wormhole usually results in a significant increase of the neighboring-node-number due to the extra attacking link. Firstly, we model the distribution of the neighboring-node-number in the form of a Bernoulli distribution. Then the model is simplified to meet the sensor nodes＇ constraints in computing and memory capacity. Finally, we propose a simple method to obtain the threshold number, which is used to detect the existence of a wormhole, Simulation results show that WAPN is effective under the conditions of different network topologies and wormhole parameters.     

Performance Improvement of Distributed Coordination Function in IEEE 802.11 Wireless LAN

This paper proposes a modification to distributed coordination function (DCF) to improve the channel utilization in IEEE 802.11 wireless local area networks (WLANs). In the modified DCF, when a station has contended for the channel, it may transmit multiple data frames continuously to the same destination, which is called transmission burst(TB). When the maximum number of data packets transmitted continuously in a TB is set to be 2, the performance is expected to be the best. The theoretical analysis and simulation results show that compared with the standard DCF, the modified DCF can increase the throughput and decrease the delay of the WLAN, and the modification does not introduce any additional control overhead.     

Relationship of public preferences and behavior in residential outdoor spaces using analytic hierarchy process and principal component analysis—— a case study of Hangzhou City, China

INTRODUCTION Nowadays, as a large number of residential blocks and college campuses are being constructed nationwide in China, improvement in the quality of residential community becomes a rising issue of city policy and urban planning. Layouts of open spaces in residential areas are predicated on their ability to deliver both a mechanism to maintain the viability of citizens’ outdoor lives and a treatment to alleviate the high-density of urban constructions. What kinds of residential o…     

The ABC of ELT... TBL ——In this Issue,Jane and Dave Willis look at Task-Based Learning

TBL, also known as TBLT (task-based learning and teaching) and, in the USA, as TBL (task-based instruction) is an approach which uses communication tasks as the central focus for language teaching and learning. Basically the term task in TBL, refers to a meaning -focused activity. There are a number of definitions in the literature, but they can be characterized also follows: the learner s principle focus is on exchanging and understanding meanings, rather than on practice of pre-specified forms or patterns there is some kind of communicative purpose or goal set for the task, so learners know what they are expected to achieve by the end tasks can involve any or all four skills, e. g. a     

Cryptanalysis of an image encryption scheme based on the Hill cipher

This paper studies the security of an image encryption scheme based on the Hill cipher （Ismail et al., 2006） and reports its following problems： （1） There is a simple necessary and sufficient condition that makes a number of secret keys invalid; （2） It is insensitive to the change of the secret key; （3） It is insensitive to the change of the plain-image; （4） It can be broken with only one known/chosen plaintext; （5） It has some other minor defects. The proposed cryptanalysis discourages any use of the scheme in practice.     

On Cyber Chatting Language in China

Chatting language is a unique phenomenon confined to the Internet.It is of great interest to a great number of re searchers.This paper is going to make a research in the following aspects:categories of cyber chatting language in China and its distinguishing features.By doing so,it is hoped that more and more people can be aware of the use of online chatting language and use it on proper occasions.     

Study of the Politeness Principle in Chinese and English cultures

This thesis attempts to make a comparative study of politeness between English and Chinese cultures.Politeness Can be realized in a number of ways,among which the use of language is an important one.With the development of pragmatics in the past years,language is used to show-politeness and also the differences between different languages and cultures.     

Conducting Web-Based Learning Support Services for Digital Immigrants A Case Study at YNOU

With the development of modern open and distance education, which is characterized by Web-based instruction, Web-based assessment, and Web-based research. Web-based learning support services are considered as the most essential inputs for digital immigrants, which offer ground for them to produce considerable outputs so as to achieve better learning outcomes. This paper examines the current situation of digital immigrants in Yunnan Open University （YNOU）, with significance of finding out specific problems so as to provide effective learning support services to solve the problems in the process of open and distance learning. Open and distance education is the instruction under digital technology by using computer as a key means of media. A digital immigrant is an individual who was born before the existence of digital technology and adopted it to some extent later in life. For considering the outreach location of Yunnan, digital immigrants are at their suitable ages of studying. Some of them cannot understand the value of digital technology completely, and some fail to implement modern technology into their daily lives. Drawing on such findings, Web-based learning support services in YNOU for digital immigrants are significantly worth studying, because they are definitely related with successful learning outcomes in order to achieve the new vision of YNOU, a newly-built open and distance university in the year of 2012. ＂Learning is ‘open＇ to everyone, study occurs by anyone, anytime, and anywhere＂ by making education accessible to all. Additionally, it is appealed for enhancing sustainable development of modern open and distance learning on the new research agenda.     

Role of Nigeria in the development of higher education in Africa

In most countries of the world, higher education is highly subsidized by the public sector. The subsidy is a result of the role of higher education sector on the economy and good governance of the nations. Enrolment into higher institutions of learning is quite low in Africa compare to other continents of the world due to the continent＇s low and declining spending on her higher institutions of learning. This shabby contribution by the continent could be likened to a result of some imminent challenges, which ranged from inadequate financial resource due to economic and social crisis to the challenges posed by the HIV/AIDS （Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome） pandemic. The contributions of Nigeria to the development of higher education in Africa is quite worthy of note. This can be affirmed by the increase in the number of states and federal universities in the country over the years since independence. This can be further reaffirmed by the promulgation of Decree 9 of 1993, which made the provision for the establishment of private universities, which further increased the nation＇s total number of universities to 93 from 59 and further strengthened the nations contributions to higher education development in the continent. In spite of all efforts made by the FGN （Federal Government of Nigeria）, the nation is yet to reach her potential in the development of her higher education sector as the percentage of potential students that gained admission into the nation＇s higher institutions of learning still stand below 15% of the total number of applicants. The study therefore recommended that budgetary allocations to higher institutions of learning be increased to meet the financial demands of the institutions. In addition, multi-campus should be encouraged in order to allow for more access to higher education.     

A Cognitive Study on Conceptual Metaphors in English News Headlines

The headline plays an important role in news report, which is a guide for readers to have a quick understanding the information of news. The headline is the"eye"of the news and it often has a lot of metaphors. The traditional theory of metaphor holds that as a rhetorical means, metaphor is mainly employed in literary works, while the theory of cognitive metaphor holds that metaphor is pervasive in our thought, action and language. The paper will discuss and analyze the characteristics of metaphors in headlines by analyzing a large number of English news examples. From the perspective of cognitive linguistics, this paper attempts to help readers to better understand the use of metaphors in headlines.     

APPENDIX A： ALTERNATIVE WAY OF OBTAINING THE LEAST-SQUARES PROBLEM

It is worth to mention that Eq.（19） can be found alternatively first by describing the boundary conditions at each of the sampling points to obtain a set of linear equations with respect to the modal coefficients Then, determining the number of sampling points in order that the number of linear equations be twice the number of unknowns     

Existence and uniqueness for a class of nine-bodies central configurations

On some necessary conditions for double pyramidal central configurations with concave heptagon for any given ratio of masses, the existence and uniqueness of a class of double pyramidal central configurations with concave heptagon base for nine-body problems is proved in this paper, and the range of the ratio cr of the circularity radius of the heptagon to the half-height of the double pyramidal central configuration involved in this class configurations is obtained, which is in the interval （√3/3,1.099 600 679）, and the configuration involved in the bodies with any σ∈ （√3/3, 1.099 600 679） can form a central configuration which is a uniquely central configuration is proved.