科学推文作者行为模式与地理分布研究

通过对2069万多条科学推文的263万多位作者做统计分析和可视化分析,揭示了科学推文作者在发文量、关注来源和关注学科方面的行为模式,以及国家层次和城市层次的地理分布,为进一步理解推特替代计量指标内涵进而科学合理应用提供基础。研究发现:(1)科学推文作者的发文量分布存在显著的集中分布规律,10%的作者发表了80%的科学推文,91%的作者发表科学推文量在10条及以下,说明存在少数科学推文量极高的作者,同时大部分作者只是偶尔在推特上传播和讨论研究成果;(2)关注作者数最多的核心来源占6%,对应77%的科学推文,尤以Nature、The Conversation和PLo S ONE居前三甲,62%的作者仅关注一种来源;(3)关注作者数最多的学科分布在医学、综合科学和社会科学,71%的作者仅在一个学科里关注研究成果,8%的作者会关注3个以上学科的研究成果;(4)科学推文作者广泛分布在世界各地,尤以美国和欧洲最为密集,东亚集中在日本,南美集中在巴西,且集中分布在伦敦、纽约、多伦多等城市。这些结果表明,纯粹基于科学推文量的推特替代计量指标有失公允,未来构建实用指标时必须将作者情境作为要素纳入考虑范围。

Application of Statistic Analysis on the Selection of Quantitative Characteristics Listed in the DUS Test Guideline of Tagetes L.

[Objective] This paper researched how to use specific approach to select quantitative characteristics which would be listed in the DUS Test Guideline of Tagetes L. [Method] With the aid of statistic analysis, the uniformity, stability and correlation of 14 pre-selected characteristics were analyzed. [Result] The expression of peduncle length of terminal flower had low uniformity within a variety; the expres- sion of main stem thickness was not stable in continuous growing cycles; there were four pairs of quantitative characteristics which are （very） significantly correlated, namely, leaf length and leaf width, diameter of flower head and length of outer ligu- late floret, number of ligulate floret whorls and number of ligulate floret, leaf width and width of terminal leaflet of pinnate leaves. Based on the requirements of char- acteristic selection and the results of statistic analysis, five characteristics including peduncle length of terminal flower, thickness of the main stem, leaf width, length of outer ligulate floret and number of ligulate floret were deleted. [Conclusion] For the first time, this paper introduced the application of statistic analysis on the selection of quantitative characteristics.

Turbulence regime near the forest floor of a mixed broad leaved/Korean pine forest in Changbai Mountains

The measurement and observation for this study were carried out by using a three-dimensional (u, v, w) Sonic anemometer (IAP-SA 485), at Forest Ecosystem Opened Research Station of Changbai Mountains (12828扙 and 4224?N, Jilin Province, P. R. China) in August 2001. The basic characteristics of turbulence, such as turbulence intensity, atmospheric stability, time scales, and convection state, near the forest floor were analyzed. It is concluded that the airflow near forest floor is characterized by high intermittence and asymmetry, and the active and upward movement takes the leading position. Near forest floor, the vertical turbulence is retained and its time scale and length scale are much less than that of u, v components. The eddy near forest floor shows a flat structure and look like a ’Disk’. Buoyancy plays a leading role in the generation and maintenance of local turbulence

A Decorrelating DOA Estimation Based on the Principal Eigenvector for CDMA Frequency-Selective Fading Channels

A novel decorrelating DOA estimation algorithm of multipath signals for CDMA frequency selective fading channels based only on the principal eigenvector of its corresponding covariance matrix is proposed. The proposed algorithm has the advantages that the DOAs of the multipath signals can be estimated independently and all the other resolved multipath signal interference is eliminated. Simulation results show that this algorithm estimates the DOAs of multipath signals efficiently and accurately.

Application of grey relational analysis in sheet metal forming for multi-response quality characteristics

The theory of grey systems is a new technique for performing prediction, relational analysis and decision making in many areas. In this paper, the use of grey relational analysis for optimizing the square hole flanging process parameters with considerations of the multiple response (the average flanging height, regular flanging and maximum strain) is introduced. Various flanging parameters, such as the blank inner radius rb, blank inner width B0, are considered. An orthogonal array is used for the experimental design. Multiple response values are obtained using finite element analysis (FEA). Optimal process parameters are determined by the grey relational grade obtained from the grey relational analysis for multi-performance characteristics (flanging height, regular flanging and maximum strain). Analysis of variance (ANOVA) for the grey relational grade is implemented. The results showed good agreement with the experiment result. Grey relational analysis can be applied in multiple response optimi-zation designs.

Improved Keystroke Authentication Accuracy Based on Statistics and Weight

Abstract： In order to improve the recognition accuracy of key stroke authentication, a methodology based on feature extraction of keystroke sequence is presented in this paper. Firstly, the data of the users＇ keystroke feature information that has too much deviation with the mean deviation is filtered out. Secondly, the probability of each input key is calculated and 10 values which do not have the best features are selected. Thirdly, they are weighed and a score evaluating the extent to which the user could be authenticated successfully is calculated. The benefit of using a third-party data set is more objective and comparable. At last,

Design of Metering Device Key Parts of Pneumatic Grass Seeder

Based on the mechanical and physical properties study of forage grass seeds, multi-line with one-device type metering device was designed. It was composed of adjustable screw, stirrer, metering device housing and central metering sheave and so on. The sowing rate can be set by turning the screw to change the working length of the central metering sheave relative to the metering device housing. The stirrer inside of the sheave housing is used to prevent seeds overhead. And metering of different sizes of seed is adjusted by changing the position of internal components of the slot wheel mechanism. Innovative design on the structure of the central metering sheave was finished. According to the structure parameters and physical characteristic parameters, different seed sowing rate of per hectares was calculated. And then the working length scale of the central metering groove wheel was made. And there is a one-to-one correspondence between scale values and sowing quantity per hectare of different kinds of seed.

Optimization Design of Vibration Characteristics of Ship Composite Brace with Rigid Vibration Isolation Mass

In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.

An experiment discovery about gravitational force changes in materials due to temperature variation

The authors discovered in first time that the weight of materials or its gravitational force by earth related to its temperature and its ferromagnetism. An experiment was designed to elevate the temperatures of six different materials （Au, Ag, Cu, Fe, Al, Ni） up to 600 ℃and precisely measured their weights. It is found all the materials weigh about 0.33 ‰ - 0. 82 ‰ less. For example the weight of silver sample weighted by a precision electronic scale in a manner of special design decreases about 0.8 ‰, when its temperature is elevated to 600 ℃. Thus different metals＇ gravitational forces or weights are adjusted with temperature variation.

The Fractional Power Law of Wind Wave Growth in Deep Water for Short Fetch

Combining the 3/2 power law proposed by Toba with the significant wave energy balance equation for wind waves, wave growth in deep water for short fetch is investigated. It is found that the variations of wave height and period with fetch have the form of power function with fractional exponents 3/8 and 1/4 respectively. Using these exponents in the power functions and through data fitting, the concise wind wave growth relations for short fetch are obtained.

A Trusted Attestation Mechanism for the Sensing Nodes of Internet of Things Based on Dynamic Trusted Measurement

Internet of things has been widely applied to industrial control, smart city and environmental protection, in these applica- tion scenarios, sensing node needs to make real-time response to the feedback control of the application layer. Therefore, it is nec- essary to monitor whether or not awareness nodes are trusted in real time, but the existing mechanisms for trusted certification lack the real-time measurement and tracking of the sensing node. To solve the above problems, this paper proposes a dynamic metric based authentication mechanism for sensing nodes of Internet of things. Firstly, the dynamic trustworthiness measure of the sensing nodes is carried out by introducing the computational function such as the trust function, the trust- worthiness risk assessment function, the feed- back control function and the active function of the sensing node. The dynamic trustworthi- ness measure of sensing nodes from multiple dimensions can effectively describe the change of trusted value of sensing nodes. Then, on the basis of this, a trusted attestation based on node trusted measure is realized by using the revocable group signature mechanism of local verifier. The mechanism has anonymity, un- forgeability and traceability, which is proved the security in the standard model. Simulationexperiments show that the proposed trusted attestation mechanism is flexible, practical and ef｜Scient and has better attack resistance. It can effectively guarantee the reliable data transmission of nodes and realize the dynamic tracking of node reliability, which has a lower impact on system performance.

Model based reference metrology for dimensional characterization of micro- and nanostructures

The requirements on the precision of dimensional metrology are especially stringent in the area of semiconductor manufacturing. This holds in particular for the measurement and control of the linewidths of the smallest structures on masks and silicon wafers and their corresponding reference metrology. In this paper we will describe the physical models and the reference instrumentation which were developed for photomask linewidth metrology at the PTB. It will be shown, how the results of the different methods can be used for comparative analyses. Application of these methods will be demonstrated exemplarily on the basis of newly developed photomask linewidth standards.

Study on Hydrodynamic Vibration in Dual Bluff Body Vortex Flowmeter

The characteristics of the dual bluff body vortex shedding is investigated, and the possibility to use dual bluff body combinations to strengthen the hydrodynamic vibration around the bluff body objects is explored. The numerical and experimental approaches were utilized to examine the time dependent flow field and the pressure oscillation around the bluff bodies. The numerical data were obtained by the advanced large eddy simulation model. The experiment was conducted on a laboratory scale of Karman vortex flowmeter with 40 mm diameter. It is revealed that the optimized dual bluff body combinations strengthened the hydrodynamic vibration. It was also found that the hydrodynamic vibration with 180° phase difference occurred at the axisymmetric points of circular pipe on the lateral faces of the equilateral triangle-section bluff bodies. Using the dual bluff body configuration and the differential sensing technique, a novel prototype of vortex flowmeter with excellent noise immunity and improved sensibility was developed.

Estimation of the Aircraft CO_2 Emissions of China's Civil Aviation during 1960-2009

Based on data collected by Chinese Civil Aviation Statistic Center, the annual CO2 emissions of aircrafts during 1960-2009 were calculated, and the emission intensity and its dynamic characteristics were analyzed. The results show that the total CO2 emissions of aircrafts in China increased from 120×10^3 t in 1960 to 41.44×10^6 t in 2009. The CO2 emission intensity decreased from 2.9 kg （converted t kra）-1 in 1960 to 0.96 kg （converted t km）-1 in 2009 at an average rate of 0.04 kg （converted t km）-I per year. The average share of CO2 emissions of aircrafts on the total CO2 emissions from the sector of transportation, storage and post was 6.6% during 1980-2005, and 0.25% on the total emissions from fossil fuel combustion during 1971-2008.

THE STATISTICAL CHARACTERISTICS OF IMPACT OF THE WESTWARD-GOING TROPICAL CYCLONES ON RAINFALL IN YUNNAN PLATEAU

Using data available from the Retrieval System Based on Yearbooks of Tropical Cyclones over the Western North Pacific,NCEP/NCAR reanalysis daily data and observed precipitation data for 1959 to 2007 in Yunnan,a province located in a low-latitude plateau,this work analyzes the climatic characteristics and the corresponding large-scale circulation patterns related to the western North Pacific westward moving TCs(WMTCs).Its impacts on the rainfall in the Yunnan Plateau are studied.Results show that WMTCs happen almost every year,mainly from July to September.It shows a downward trend in decadal variation.Nearly the entire Yunnan area is affected by them but the eastern part experiences the most severe influences.Most of the WMTCs migrate from the South China Sea,primarily make landfall in Hainan and Guangdong and enter the Northern Bay.The tracks of these typhoons can be classified into five categories,in which the most significant impact results from those making landfall in Guangdong.All categories of the tropical cyclones can induce province-wide heavy rainfall in Yunnan.Super typhoons bring about the heaviest and most extensive rainfall over the low-latitude plateau while the associated circulation pattern is marked with a dominant 500 hPa meridional circulation at middle latitudes,an active monsoon depression and Intertropical Convection Zone(ITCZ) at low latitudes and a westward-located South Asia High at 100 hPa,which is favorable for tropical cyclones to travel westward.WMTCs tend to go westward into the interior part of China if the subtropical high extends its westernmost ridge point to the northeast of Yunnan,or expands its periphery anti-cyclonic circulation to the Tibetan Plateau,or merges with the Qinghai-Tibetan high.

A New Statistical Tool： Scalar Score Function

The basic inference function of mathematical statistics, the score function, is a vector function. The author has introduced the scalar score, a scalar inference function, which reflects main features of a continuous probability distribution and which is simple. Its simplicity makes it possible to introduce new relevant numerical characteristics of continuous distributions. The t-mean and score variance are descriptions of distributions without the drawbacks of the mean and variance, which may not exist even in cases of regular distributions. Their sample counterparts appear to be alternative descriptions of the observed data. The scalar score itself appears to be a new mathematical tool, which could be used in solving traditional statistical problems for models far from the normal one, skewed and heavy-tailed.

Statistical Properties and Algebraic Characteristics of Quantum Superpositions of Negative Binomial States

We introduce new kinds of states of quantized radiation fields, which are the superpositions of negative binomial states. They exhibit remarkable nonclassical properties and reduce to Schr?dinger cat states in a certain limit. The algebras involved in the even and odd negative binomial states turn out to be generally deformed oscillator algebras. It is found that the even and odd negative binomial states satisfy the same eigenvalue equation with the same eigenvalue and they can be viewed as two-photon nonlinear coherent states. Two methods of generating such the states are proposed.

Multi-Aspect Value of Measuring Systems and Methods Based on the Results of Roundness Measurements

The increase of quality consciousness brings about the growth of significance of metrological systems. Besides the significance, the level of automatization, flexibility, accuracy, et al. have advanced. The modern measuring systems are constructed so that nearly all necessary dimensional characteristics can be measured with them. However, conventional measuring systems are provided for particular mode measurements. This research paper presents and compares several conventional and modem measuring systems and methods. The measured value is roundness, one of the basic shapes of cross section in mechanical engineering. This paper arises in search of answers for the question whether conventional measuring techniques and equipments are made redundant because of the modern ones. In what segments and in which criterion are modem methods preferable？

Theoretical Calculations for Structural, Elastic and Thermodynamic Properties of MgB2 under High Pressure

We have investigated the structural and elastic properties of MgB2 under high pressures using the full- potential linearized muffin-tin orbital （FP-LMTO） scheme within the generalized gradient approximation correction （GGA） in the frame of density functional theory. The calculated pressure dependence of the normalized volume is in excellent agreement with the experimental results. At the same time the elastic constants and acoustic anisotropy as a function of applied pressure are presented. Through the quasi-harmonic Debye model, we also investigate the thermodynamic properties of MgB2.

Inverse Eigenvalue Problems for a Structure with Linear Parameters

The inverse design method of a dynamic system with linear parameters has been studied. For some specified eigenvalues and eigenvectors, the design parameter vector which is often composed of whole or part of coefficients of spring and mass of the system can be obtained and the rigidity and mass matrices of an initially designed structure can be reconstructed through solving linear algebra equations. By using implicit function theorem, the conditions of existence and uniqueness of the solution are also deduced. The theory and method can be used for inverse vibration design of complex structure system.