在确定贴现率的条件下估计风险

在确定贴现率的条件下估计风险薛蓓蕾译在市场经济条件下，估计投资效益一般是根据投资的逐年收益累积的贴现来进行计算的，这种方法经常用来估计私有企业的财产的未来收益。关键是要确定贴现率Ｅ，由此来计算不同时期的消耗和收益。在规定贴现率后，才能考虑可供选择的和...

e的上、下界估计及其区间长度

该文证明了：（１）ｂ＞０，ｘ≥ｂ，１＋１ｘｘ１＋１２＋１ｂｘ＜ｅ＜１＋１ｘｘ１＋１２ｘ；（２）ａ＞０，１＋１ｎｎ１＋１ａｎ＜ｅ＜（１＋１ｎ）ｎ１＋１２ｎ（ｎ＝１，２，３，…）ａ＞２ｅ－２．上述两个结果推广和改进了Ｋｌａｍｂａｕｅｒ的相应结果．

具有二次约束的二次规划全局最优性条件

本文讨论具有二次约束与超矩形约束的非凸二次规划问题的新型全局最优性充分条件,这些新的全局最优性充分条件是利用二次函数的二次下估计函数获得的.我们首先介绍如何构造二次函数的下估计函数.然后利用在KKT点处的拉格朗日函数的凸二次下估计函数建立非凸二次规划问题的全局最优性充分条件,再利用最小特征根与二次下估计函数获得它的全局最优性充分条件.最后利用二次下估计函数建立具有二次约束的非凸二次规划问题的全局最优性充分条件.

The Estimation for Lower Bounds of the Solutions of Fermat's Equation

Let p be a prime with p≡3(mod 4). In this paper,by using some results relate the representation of integers by primitive binary quadratic forms,we prove that if x,y,z are positive integers satisfying x^p+y^p=z^p, p|xyz, x<y<z, then y>p^(6p-2)/2.

A comparative assessment of rock mass deformation modulus

Deformation modulus of a rock mass(E_m) is one of the most important design parameters in construction of rock engineering projects such as underground excavations.However,difficulties are frequently encountered during in-situ tests which are also time-consuming and expensive for determining this parameter.Although E_m is often estimated indirectly from proposed equations by different researchers,many of these equations cannot be used in case of problematic rock conditions(thinly bedded,highly jointed rock masses,etc.) as high quality core samples are required.This study aims to explore more practical and useful equation for E_m estimation using Rock Quality Designation(RQD) and point load index values.Comparisons were made between available empirical equations and the proposed E_m equation in terms of the estimation capacity.Multiple comparison tests(ANOVA) showed that E_m can be reliably estimated using proposed equation especially at the preliminary stages of projects.

Frequency Diversity for OFDM Mobile Communication via Underwater Acoustic Channels

The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication （UWAC） based on OFDM were carried out with 0.17 bit/（s-Hz） spectral efficiency. The validity and the dependability of the scheme were also analyzed.

Upper Bound and Lower Bound Estimate of Monotone Increasing Fractal Function

Mass distribution principle is one of important tools in studying Hausdorff dimension and Hausdorff measure. In this paper we will give a numerical approximate method of upper bound and lower bound of mass distribution function f（x）（it is a monotone increasing fractal function） and its some applications.

Introducing Fractal Dimension to Estimation of Soil Sensitivity to Preferential Flow

Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil profiles were then photographed and the photos were scanned into a computer. Edited with certain software, only the dyed areas were left on the profile photos, which indicted the preferential flow paths for water and solute transport. Fractal dimensions of the dye patterns were calculated according to Arnold's function. Soil particle size distribution was analyzed by pipette method. The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile. Based on the experiment results, the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.

Estimation of Antropogenenic Pressure on Landscapes of Oasises （on Example of Mid and Lower Part of Zarafshan River）

The paper discusses about anthropogenic pressure classification system on landscape oasises. As a result, based on designed criteria rates a thematic map titled ＂Anthropogenic pressure and its consequences on landscapes oasises of mid and lower part of Zarafshan River Basin＂ was developed. The thematic map depicts realthionship between ecological conditions and population diseases along various landscape oasises of the Zarafshan river valley.

Linear Track Estimation Using Double Pulse Sources for Near-Field Underwater Moving Target

The double pulse sources （DPS） method is presented for linear track estimation in this work. In the field of noise identification of underwater moving target, the Doppler will distort the frequency and amplitude of the radiated noise. To eliminate this, the track estimation is necessary. In the DPS method, we first estimate bearings of two sinusoidal pulse sources installed in the moving target through baseline positioning method. Meanwhile, the emitted and recorded time of each pulse are also acquired. Then the linear track parameters will be achieved based on the geometry pattern with the help of double sources spacing. The simulated results confirm that the DPS improves the performance of the previous double source spacing method. The simulated experiments were carried out using a moving battery car to further evaluate its performance. When the target is 40-60m away, the experiment results show that biases of track azimuth and abeam distance of DPS are under 0.6° and 3.4m, respectively. And the average deviation of estimated velocity is around 0.25m/s.

Buckling Load Evaluation Method for Single Layer Cylindrical Lattice Shells

A rational design evaluation procedure is investigated for the elastic overall buckling load carrying capacity of single layer cylindrical lattice shell roof structures. The nature of the imperfection sensitivity of these structures is for the first time reviewed in this paper. This allows the development of the reduced stiffness buckling analytical concept for the lattice shells based upon the introduction of a simple lower bound estimation equation through the use of the so-called continuum shell analogy theory. The linear and nonlinear buckling loads found from conventional finite element analyses are compared with the present estimations. Finally, the elastic-plastic load carrying capacity estimation method through the use of the present elastic lower bound criteria is also proposed.

Research and simulation on synchronization algorithm of PSS in a 5G system based on block cross-correlation

In response to the downlink synchronization requirements of the user equipment(UE)or third-party radio equipment in fifth-generation(5G)mobile communication systems,a synchronization algorithm of primary synchroni-zation signal(PSS)was designed and developed in the 5G system based on block cross-correlation.According to the new characteristics of the 5G synchronization channel and broadcast channel,starting from the traditional downlink synchronization algorithm of long-term evolution(LTE),the detection performance of the algorithm under a low signal-to-noise ratio(SNR)is improved by introducing an incoherent accumulation,and the new scheme of joint coarse frequency offset estimation is used to improve the frequency offset estimation performance.Finally,the performance of the proposed synchronization algorithm is verified by conducting a simulation on a 5G downlink simulation platform based on MATLAB software.Simulation results show that the improved downlink synchronization algorithm has stable performance in the tapped delay line-C(TDL-C)and additive white Gaussian noise(AWGN)channels with large frequency deviation and low SNR.

Two-dimensional DOA estimation based on thin array towed by a small autonomous platform

The small autonomous platform with a thin line array is an important tool for underwater acoustic mobile surveillance.Generally,only one-dimensional(1-D)direction-of-arrival(DOA)of the source signal can be estimated using a thin towed line array.In this work,the two-dimensional(2-D)DOA estimation is achieved by the thin line array towed by a small autonomous platform due to its flexible maneuver.Two perpendicular tow paths are formed through the fast turning of this array.An L-shaped array is formed by the same towed array on these two tow paths at different times.Using the array on these two straight paths,two 1-D DOAs of the source signal are obtained respectively,and then the 2-D DOA based on the formed L-shaped array can be estimated.The effectiveness of proposed approach is verified by numerical simulations and its theoretical error is analyzed.

Statistical Properties and Confidence Limits about the Mean Time between the Failures (MTBF) in Failure-free Period Life Test (FFPLT)

On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and corresponding calculating formulae are found out.

Assessment of Groundwater for Heavy Metals in Selected Areas of North Lebanon

Heavy metals are ubiquitous in the environment and their consumption can create a potential hazard to human health, Lebanon is one of the richest countries in the Middle East. This study was undertaken to assess some of the heavy metals in drinking ground water of north Lebanon. Forty five ground water samples were collected from three different areas, the region of Bcharreh, a high mountain area, the region of Bessebaal, a semi industrial area and the region of Chekka, a sea level highly industrial area. Lead, chromium, zinc and copper were estimated using atomic absorption spectrometer. This study revealed high concentration of lead in the Bessebaal and Chekka areas （0.1328 mg/L, 0.3751 mg/L, respectively）; whereas chromium was estimated to be high in all three regions, 0.2429 mg/L, 0.2249 mg/L and 0.2443 mg/L in Bcharreh, Bessebaal and Chekka, respectively. Alternatively zinc showed a high concentration only in Bessebaal and Chekka （0.3715 mg/L, 0.3216 mg/L, respectively）, while, a low level of zinc （0.0393 mg/L） was detected in Bcharreh. As for copper, it was only detected in Chekka （0.0019 mg/L）.This study shined the light on the importance of heavy metals screening in our drinking water hence suggesting the developing of a successful programs for testing the quality of water sources before using it for drinking purpose.

Design of an Index System for Deep Groundwater Management Efficiency Evaluation: A Case Study in Tianjin City, China

An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index system is specifically developed to evaluate deep groundwater management efficiency. It is composed of three first-level indicators(law enforcement capability, management ability, and management effectiveness) and eleven second-level indicators. The second-level indicators include seven mandatory indicators and four optional indicators. Piecewise linear function is used to normalize the quantitative indicators, and expert scoring method and questionnaire survey method are used to normalize the qualitative indicators. Then a comprehensive indicator weighting evaluation method is used to evaluate the first-level indicators and the target topic. A case study is carried out to evaluate deep groundwater management efficiency in Tianjin City. According to the evaluation score in each period, the management efficiency of every district in Tianjin City gradually improved. The overall evaluation score in the early deep groundwater extraction period is 0.12. After a series of deep groundwater protection efforts, this score reached to 0.61 in 2007, and met the regulation criteria. The evaluation results also showed that the further groundwater management efforts in Tianjin City should be focused on building a dynamic database to collect comprehensive deep well-log data; and on a reasonable design and distribution of the groundwater monitoring network. It demonstrated that the index system is suitable to locate the deficiencies of current groundwater management systems and to guide further improvements. It can then be used to protect deep groundwater.

基于UKF的雷达和机载ESM扩维跟踪

为有效提高异类传感器融合跟踪的效果,提出了一种基于UKF的雷达和机载ESM扩维跟踪算法。首先将目标和机载ESM的状态信息组合起来,形成一个高维的状态向量,从而有效抑制滤波中GPS定位误差所带来的影响;接着在此基础上采用UKF来实现目标的定位跟踪,以求进一步减小扩维后线性化误差加大等问题的影响。仿真结果表明,该算法可更好地实现对目标的定位跟踪。

具有超矩形约束的三次规划的全局最优性条件

研究了一类具有超矩形约束的特殊三次规划问题,利用目标函数的三次上估计函数与下估计函数推导出该问题的全局最优必要性与充分性条件。首先,构造如下形式的三次上估计函数与下估计函数h(x)=l(x)-l(x)+f(x),其中f(x)是目标函数,l(x)=∑n i=113αix3i+12xTQx+(b+(A-Q)x)Tx。接着利用三次上估计函数建立判断一个可行点是全局最优点的全局最优必要性条件。然后利用三次下估计函数建立判断一个可行点是全局最优点的全局最优充分性条件:τipi(xi)+τimin{γipi(ui),γipi(vi)}≥0,i∈I,τipi(xi)≤0与pi(xi)=0,i∈J。一些实例说明了这些全局最优必要性与充分性条件的有效性与可行性。

一类混合整数约束三次规划问题的全局最优性条件

通过构造目标函数的二次上估计函数和二次下估计函数,给出了一类混合整数三次规划问题的全局最优性条件。首先利用二次上估计函数给出全局最优性必要条件,其次再利用二次下估计函数获得全局最优性充分条件。最后给出一个数值例子来说明如何利用所给出的全局最优性条件来判定一个给定的点是否是全局最优解。

Eigenvalue Comparison Theorems on Finsler Manifolds

Cheng-type inequality, Cheeger-type inequality and Faber-Krahn-type inequality are generalized to Finsler manifolds. For a compact Finsler manifold with the weighted Ricci curvature bounded from below by a negative constant, Li-Yau's estimation of the first eigenvalue is also given.