北京地区山背波监测与特征分析

利用北京西北地区布置的小孔径大气次声传感器网络,利用有效来波判断方法搜寻有效来波,并使用最小方差空间搜索方法定位波源,分析经常发生并对正常观测造成干扰的一种次声波—山背波信号的特征规律：幅度、频谱、波源位置、波速、来波方向及发生时间统计规律。对2013年4~5月的次声波记录数据进行分析,结果显示：低于0.02 Hz频段,各传感器经常性接收到来自于西北山区方位的次声波,幅度一般在10~20 Pa,中心频率处于0.002~0.005 Hz,最小方差法定位结果显示信号源大多自北京西山的面向阵列的一侧,方位角统计结果显示大多数在260°~360°、0°~40°,且传播速度为10~50 m/s,该波的发生与当地的风速风向具有相关性。

山背波:对飞机的潜在威胁

山背波河飞机的潜在威胁现已毋庸置疑．为了提高在这方面作出更确切判断的能力并能进一步找出实践中可行的相应措施，首要的问题就是必须对山背波本身有足够的认识，而这正是当前国内文献中极为薄弱的环节．有鉴于此，本文系统地、较全面地介绍了山背波这种独特的次声波，对其发生机理和基本特征、以及作为其直接衍生物的相关云相和晴空湍流──—后者正是对飞机的主要潜在威胁所在──—作出简明扼要的评述．

光子带隙光纤背向散射次波建模及实验验证

光子带隙光纤有着独特的结构形式、传输介质和导光机制,这使其具有传统光纤无法比拟的优点,是未来光纤陀螺的理想选择。但光子带隙光纤粗糙的纤芯内壁导致其产生强烈的背向散射次波,会使光子带隙光纤陀螺产生额外的非互易误差。为了定量分析光子带隙光纤背向散射次波强度大小,论文基于电偶极子辐射理论建立了一种简单的光子带隙光纤背向散射次波理论模型。通过聚焦离子束微纳加工法和原子力显微镜测量得到了准确的纤芯内壁表面形貌功率谱密度,进而计算得到HC-1550-02型光子带隙光纤背向散射系数理论值为2.61×10^(-9)/mm。通过光频域背向反射散射仪得到HC-1550-02型光子带隙光纤背向散射系数测量值为~1.82×10^(-9)/mm,初步验证了背向散射次波模型的正确性,为背向散射次波抑制技术研究奠定了基础。

露天矿背波台阶边坡受爆破振动的影响

针对露天矿背波台阶边坡的爆破振动高程放大效应,基于FLAC^(3D)研究了爆源与台阶边坡在不同水平距离、不同高程差的情况下,背波台阶坡面的高程放大效应.结合哈尔乌素露天煤矿北端帮工程实际,对该露天矿北端帮工程进行现场监测,并将监测结果与数值模拟结果进行对比分析,进一步验证了背波台阶坡面的高程放大效应.该结论对后续工程和类似工程具有一定指导和参考价值.

基函数网络逼近:进展与展望

从神经网络、统计估计、逼近论、调和分析等角度研究了多变量目标函数的逼近问题 ,评述了这些工具的逼近效率和能力 ,同时研究和评述了脊波 (Ridgelet)的发展现状及应用前景 。

A Practical Backside Technology for Indium Phosphide MMICs

A wet etching process for backside via holes suitable for use on InP MMICs technologies is developed for indium phosphide substrate.PMMA is used to mount InP wafer onto glass carrier.Spattered Ta film is utilized as etch mask.HCl+H 3PO 4 solution realised a etch until a depth of 100μm.It is demonstrated that the wet etching backside process is controllable with large latitudes.

Unification of Dark Matter and Dark Energy in a Modified Entropic Force Model

In Verlinde＇s entropic force scenario of gravity, Newton＇s laws and Einstein equations can be obtained from the first principles and general assumptions. However, the equipartition law of energy is invalid at very low temperatures. We show clearly that the threshold of the equipartition law of energy is related with horizon of the universe. Thus, a one-dimensional Debye （ODD） model in the direction of radius of the modified entropic force （MEF） may be suitable in description of the accelerated expanding universe. We present a Friedmann cosmic dynamical model in the ODD-MEF framework. We examine carefully constraints on the ODD-MEF model from the Union2 compilation of the Supernova Cosmology Project （SCP） collaboration, the data from the observation of the large-scale structure （LSS） and the cosmic microwave background （CMB）, i.e. SNe Ia＋LSS＋CMB. The combined numerical analysis gives the best-fit value of the model parameters （ -10^-9 and Ωm0= 0.224, with 2 = Xmin= 591.156. The corresponding age of the universe agrees with the result of D. Spergel et al. [J.M. Bardeen, B. Carter, and S.W. Hawking, Commun. Math. Phys. 31 （1973） 161] at 95% confidence level. The numerical result also yields an accelerated expanding universe without invoking any kind of dark energy. Taking ζ（= 2πωD/ H0 ） as a running parameter associated with the structure scale r, we obtain a possible unified scenario of the asymptotic flatness of the radial velocity dispersion of spiral galaxies, the accelerated expanding universe and the Pioneer 10/11 anomaly in the entropic force framework of Verlinde.

Travel Motivation of Domestic Tourists to the Changbai Mountain Biosphere Reserve in Northeastern China: A Comparative Study

This article seeks to develop a fuller understanding of the social and attraction motives of domestic tourists who visit the Changbai Mountain Biosphere Reserve(CMBR) in Northeastern China. To do so, ecotourists are compared to general travelers visiting this area. A questionnaire was employed to collect data on visitor characteristics and motivations, responses to which were then analyzed via descriptive statistics, T-tests and principal component factor analysis. Results showed that 16% of the visitors to this area were classified as ecotourists, while the remainder general travelers. Five motivations displayed significant differences(P<0.05) between these two types of tourists. Three social motives – boosting self-confidence, feeling at home away from home and being together with family – and two attraction motives – indoor sports and viewing unique landscapes of the CMBR(crater lake, waterfall, gorge and hot spring) – were significantly more important for general travelers(P<0.05); while two social motives of experiencing the tranquility of the natural setting and the natural beauty of the landscape were relatively more important for ecotourists(P<0.1). Results suggest that ecotourists have distinct and complicated attraction and social motives compared to general travelers visiting the CMBR. Results have useful implications for researchers interested in tourist motivations and behavior, as well as for managers who wish to focus their marketing strategies more effectively. National Park of South Africa. Uysal et al.(1994) assessed the travel motives of Australian tourists to U.S. national parks and nature areas and formed five groupings including ‘relaxation/hobbies', ‘novelty', ‘enhancement of kinship relationship', ‘escape', and ‘prestige'. Tao et al.(2004) analyzed motivations of Asian tourists travelling to Taiwan's Taroko National Park using a self-defined approach and found that the most significant benefits sought by self-defined ecotourists are ‘learning about nature' and ‘participating in recreation activities'. Beh and Bruyere(2007) analyzed visitor motivations in three Kenyan national reserves, identifying the three most prominent kinds of tourists as escapers, learners and spiritualists. Pan and Ryan(2007) used factor analysis to reveal five motivational dimensions –‘relaxation', ‘social needs', ‘a sense of belonging', ‘mastery skills', and ‘intellectual needs' – of visitors to the Pirongia Forest Park in New Zealand. Kruger and Saayman(2010) did a comparative study on travel motivations of tourists to Kruger and Tsitsikamma National Parks in South Africa and found that common motives of tourists were ‘escape and relaxation' as well as ‘knowledge seeking', ‘nostalgia' and ‘park attributes'. Despite these efforts, on an overall basis past literature on why visitors travel to national parks and nature areas is still rather limited. In China, a number of empirical studies on tourist motivations have been conducted since the early 1990s(Chen and Miao 2006; Dong 2011; Huang et al. 2011; Jeffrey and Xie 1994; Lu 1997; Ma et al. 2013; Zhang 2012). Some studies have focused on motivations of visitors to nature reserves(Li 2007), geological parks(Chen and Qiao 2010), world heritage sites(Su et al. 2005), and seismic memorial sites(Tang 2014). However, most previous research findings on tourist motivations are not comparable, reflecting the fact that visitors to different parks have quite different motives due to the attributes of particular destinations, the geographic locations of these parks, types of available activities, marketing strategies, and the complexity of travel motives(Chen and Qiao 2010; Pan and Ryan 2007). While it is true that certain motivations were shared in varying degrees by most tourists to these places – i.e., ‘appreciating natural landscapes', ‘family and education', ‘social needs', and ‘perceived prestige of visit' – most previous research has not focused on natural settings as destinations. Thus travel motivations of tourists to these areas must be further explored and clarified in relation to impacts on particular natural areas and patterns of market segmentation. As one of the earliest and largest natural reserves established in China, the Changbai Mountain Biosphere Reserve(CMBR) has long been a draw not only for domestic tourists but also for international visitors, and tourism to the area has been growing steadily since 1980. With the number of visitors to the reserve having climbed to 2.44 million in 2010(Statistical Communiqué of the Changbai Mountain Protection and Development Zone of Jilin Province 2011), it has become imperative for local government officials and reserve wardens to understand tourists' desires and interests when identifying tourism development opportunities. However, the existing literature still suffers from a lack of empirical studies that investigate why people travel to the CMBR and whether tourist motives differ between groups such as ecotourists and general travelers. The target population for this study consists of domestic visitors to the CMBR. The goals of this research include:(1) to identify the social and attraction motives of domestic tourists that influence decisions to visit the CMBR;(2) to explore whether there are any differences between the motivations of these two types of tourists; and(3) to provide some useful management implications for local government and tourism marketers.

PERFORMANCE EVALUATION OF OSSO-CFAR WITH BINARY INTEGRATION IN WEIBULL BACKGROUND

The performance of the Ordered-Statistic Smallest Of (OSSO) Constant False Alarm Rate (CFAR) with binary integration in Weibull background with known shape parameter is analyzed, in the cases that the processor operates in homogeneous background and non-homogeneous situation caused by multiple targets and clutter edge. The analytical models of this scheme for the performance evaluation are given. It is shown that the OSSO-CFAR with binary integration can greatly improve the detection performance with respect to the single pulse processing case. As the clutter background becomes spiky, a high threshold S of binary integration (S/M) is required in order to obtain a good detection performance in homogeneous background. Moreover, the false alarm performance of the OSSO-CFAR with binary integration is more sensitive to the changes of shape parameter or power level of the clutter background.

Elastic-energy imaging condition based on energy-flow vector

Elastic reverse-time migration can effectively deal with multicomponent seismic data in which the imaging condition based on energy norm can extract the scalar-imaging result from multicomponent data.However,the energy cross-correlation imaging condition characterized by particle velocity and stress suffers from the problem of overdependence on the background elastic parameters.Therefore,we characterize the elastic-wave energy using the energy-flow vector,which is equal to the energy density,without background elastic parameters.According to the source and receiver wave fields,we propose an imaging energyflow vector and an elastic-wave energy imaging condition.Under the assumption of a planewave solution,the backscattering suppression is verified.The numerical simulations show that the elastic-energy imaging condition can obtain the energy image without backscattering.Compared with the cross-correlation imaging conditions in a vector-based wave field,the proposed imaging condition can eliminate the dependence on the background elastic parameters and effectively process seabed multicomponent data,which are conducive to further providing an interpretation of marine geological structures.

Improvement Methods for Genetic Evaluation of Hanwoo Cows

A total of 1,101 heads were used to improve the selection of superior cows in Gangwon regional Hanwoo. Characteristics of each cow were analyzed using ultrasound evaluation and trace of reproductive potential. A comparison of live carcass traits classified by parity was analyzed in all characteristics. The results of the comparison showed all characteristic increased rapidly after the 2nd parity, and decreased after the 4th parity （P 〈 0.01）. The result of comparison classified by the group showed a tendency, whereas Back Fat Thickness Ultrasound （BFTU） and P8 Fat Thickness Ultrasound （P8-FTU） were significant （P 〈 0.01） thinnest in Pedigree group and using a lot of reproduction in advanced group. Also, we made comparisons of the cow＇s calves on the carcass traits among the group. High quality calves of the pedigree group showed 30.77%. These are the highest carcass traits in meat quality grade above 1＋ and yield grade above A. Frequency of fertilization failure per rump fat thickness showed a significantly （P 〈 0.0｜） higher difference. The average frequency of fertilization failure demonstrated 1.11 times of experimental Hanwoo cows. In the analysis, frequency of fertilization failure appeared 0.9 times at rump fat thickness below 5 mm. However, it is higher than average above 5 mm. The result of the study will be used to improve cows, select optimum semen, as well as contribute to the improvement of farms income.

Instantaneous Real-Time Detection Technology of GLI on FY-4 Geostationary Meteorological Satellite

Lightning is a typical example of an instantaneous random point source target. It has close connection with severe convective phenomena such as a thunderstorm, whose distribution, variation, position and forecasting can be acquired through lightning observation. In this paper, we discuss the way to achieve instantaneous lightning signal intensification and detection from geostationary orbit by using the differences between the lightning signal and the slowly changing background noise such as that of cloud, land and ocean, combining three methods, spectral filtering, spatial filtering and background noise, enabling removal between frames. After six months of operation in orbit, lightning within the coverage of the Geostationary Lightning Imager was effectively detected, strongly supporting the case for shorttime and real-time early warning, forecasting and tracking of severe convective phenomena in China.

Research on Gaussian distribution preprocess method of infrared multispectral image background clutter

This paper introduces a sliding-window mean removal high pass filter by which background clutter of infrared multispectral image is obtained. The method of selecting the optimum size of the sliding-window is based on the skewness-kurtosis test. In the end, a multivariate Gaussian distribution mathematical expression of background clutter image is given.

Experimental study and analysis of shock train self-excited oscillation in an isolator with background waves

A study of shock train self-excited oscillation in an isolator with background waves was implemented through a wind tunnel experiment.Dynamic pressure data were captured by high-frequency pressure measurements and the flow field was recorded by the high-speed Schlieren technique.The shock train structure was mostly asymmetrical during self-excited oscillation,regardless of its oscillation mode.We found that the pressure discontinuity caused by background waves was responsible for the asymmetry.On the wall where the pressure at the leading edge of the shock train was lower,a large separation region formed and the shock train deflected toward to the other wall.The oscillation mode of the shock train was related to the change of wall pressure in the oscillation range of its leading edge.The oscillation range and oscillation intensity of the shock train leading edge were affected by the wall pressure gradient induced by background waves.When located in a negative pressure gradient region,the oscillation of the leading edge strengthened;when located in a positive pressure gradient region,the oscillation weakened.To find out the cause of self-excited oscillation,correlation and phase analyses were performed.The results indicated that the instability of the separation region induced by the leading shock was the source of perturbation that caused self-excited oscillation,regardless of the oscillation mode of the shock train.

Revisit of constraints on holographic dark energy:SNLS3 dataset with the effects of time-varying β and different light-curve fitters

Previous studies have shown that for the Supernova Legacy Survey three-year （SNLS3） data there is strong evidence for the redshifl- evolution of color-luminosity parameter β of type Ia supernovae （SN Ia）. In this paper, we explore the effects of varying β on the cosmological constraints of holographic dark energy （HDE） model. In addition to the SNLS3 data, we also use Planck distance prior data of cosmic microwave background （CMB）, as well as galaxy clustering （GC） data extracted from Sloan Digital Sky Survey （SDSS） data release 7 and Baryon Oscillation Spectroscopic Survey （BOSS）. We find that, for the both cases of using SN data alone and using SN＋CMB＋GC data, involving an additional parameter of β can reduce χ^2 by - 36; this shows that β deviates from a constant at 6σ- confidence levels. Adopting SN＋CMB＋GC data, we find that compared to the constant β case, varying β yields a larger fractional matter density Ωm0 and a smaller reduced Hubble constant h; moreover, varying β significantly increases the value of HDE model parameter c, leading to c ≈ 0.8, consistent with the constraint results obtained before Planck. These results indicate that the evolution of β should be taken into account seriously in the cosmological fits. In addition, we find that relative to the differences between the constant β and varying β（z） cases, the effects of different light-curve fitters on parameter estimation are very small.

Constraints of f(R) gravity in Palatini approach with observational Hubble data

We use the newly released observational H(z) data (OHD), the Cosmic Microwave Background (CMB) shift parameter, and the Baryon Acoustic Oscillation (BAO) measurements data to constrain cosmological parameters of f(R) gravity in Palatini formalism in which the f(R) form is defined as f(R) = R β/Rn. Under the assumption of a spatially flat FRW universe, we get the best fitting results of the free parameters (Ωm0, n). In the calculation, we marginalize the likelihood function over H0 by integrating the probability density P ∝ e-χ2/2 to obtain the best fitting results and the confidence regions in the Ωm0-n plane. The constraints results of (Ωm0, n) = (0.33, 0.41) by OHD only and (Ωm0, n) = (0.23, 0.08) by the combination of OHD+CMB+BAO both indicate that the universe goes through three last phases, i.e., radiation dominated, matter-dominated, and late time accelerated expansion without introduction of dark energy.

Constraints on the extensions to the base ΛCDM model from BICEP2, Planck and WMAP

Recently Background Imaging of Cosmic Extragalactic Polarization （B2） discovered the relic gravitational waves at 7.00- confi- dence level. However, the other cosmic microwave background （CMB） data, for example Planck data released in 2013 （P13）, prefer a much smaller amplitude of the primordial gravitational waves spectrum if a power-law spectrum of adiabatic scalar perturbations is assumed in the six-parameter ACDM cosmology. In this paper, we explore whether the wCDM model and the running spectral index can relax the tension between B2 and other CMB data. Specifically we found that a positive running of running of spectral index is preferred at 1.70- level from the combination of B2, P 13 and WMAP Polarization data.

Prospects for improving cosmological parameter estimation with gravitational-wave standard sirens from Taiji

Taiji,a space-based gravitational-wave observatory,consists of three satellites forming an equilateral triangle with arm length of 3×10^6 km,orbiting around the Sun.Taiji is able to observe the gravitationalwave standard siren events of massive black hole binary(MBHB)merger,which is helpful in probing the expansion of the universe.In this paper,we preliminarily forecast the capability of Taiji for improving cosmological parameter estimation with the gravitational-wave standard siren data.We simulate fiveyear standard siren data based on three fiducial cosmological models and three models of MBHB’s formation and growth.It is found that the standard siren data from Taiji can effectively break the cosmological parameter degeneracies generated by the cosmic microwave background(CMB)anisotropies data,especially for dynamical dark energy models.The constraints on cosmological parameters are significantly improved by the data combination CMB+Taiji,compared to the CMB data alone.Compared to the current optical cosmological observations,Taiji can still provide help in improving the cosmological parameter estimation to some extent.In addition,we consider an ideal scenario to investigate the potential of Taiji on constraining cosmological parameters.We conclude that the standard sirens of MBHB from Taiji will become a powerful cosmological probe in the future.

RCS analysis in the detection of a generic missile target with sea clutter background

The detection of a missile target in heavy sea clutter is a significantly challenging problem due to the clutter effects. In this paper, the radar cross sections(RCS) of a pre-assumed generic missile model is computed with multilevel fast multi-pole algorithm(MLFMA), while the RCS of ocean surface is computed by a more reduced form of the fractional Weierstrass scattering model proposed here. At last, the computed RCS of missile model is compared with that of sea surface, and then the comparisons of missile-to-ocean RCS ratios of different incident angles, incident frequencies, and polarization patterns are also presented. The discussion and comparisons of RCS of the missile and ocean surface can help us to plan and design a radar system in the application of detection of a missile target or other analogous weaker targets in the strong sea clutter background.