唐山矿机械化采样器运动原理的评析与新的优化

唐山矿新研制了一种应用于皮带运输机的双臂全断面煤流自动取样机。笔者对该机的主要部分－采样器作出了理论分析和探讨，同时提出了新的优化设想。

南京栖霞山铅锌矿取样工作改进措施

随着矿山管理水平的进步,对原矿品位的预测和后期控制要求越来越高。按以往矿山的取样方式难以满足现代矿山精细化作业的需要,矿山取样措施改进势在必行。以南京栖霞山铅锌矿为背景,介绍了进路巷道取样、采场现场抓样、钻孔取样设备更新、井口样单车矿石质量分析等取样改进措施。结果表明,采场取样改进使采场生产布置更合理有序,钻孔取样改进大幅提高工作效率,矿车单车质量分析全面掌握各采场的真实出矿情况,在矿山现有条件的基础上实现矿山取样工作的全方位提升,为企业的经济效益提供坚实的保障。

Seismic data analysis based on spatial subsets

There are some limitations when we apply conventional methods to analyze the massive amounts of seismic data acquired with high-density spatial sampling since processors usually obtain the properties of raw data from common shot gathers or other datasets located at certain points or along lines. We propose a novel method in this paper to observe seismic data on time slices from spatial subsets. The composition of a spatial subset and the unique character of orthogonal or oblique subsets are described and pre-stack subsets are shown by 3D visualization. In seismic data processing, spatial subsets can be used for the following aspects： （1） to check the trace distribution uniformity and regularity; （2） to observe the main features of ground-roll and linear noise; （3） to find abnormal traces from slices of datasets; and （4） to QC the results of pre-stack noise attenuation. The field data application shows that seismic data analysis in spatial subsets is an effective method that may lead to a better discrimination among various wavefields and help us obtain more information.

CONTOUR EXTRACTION AND FEATURE POINT DETECTION FOR 3-D FRAGMENT REASSEMBLY

An approach to contour extraction and feature point detection in the 3-D fragment reassembly is proposed. A simple and effective technique is used for building the intrinsic topology of the fragment data suitable for contour extraction. For the scanned data in which the topology is difficult to be achieved, the corresponding solutions are given to manage this problem. A robust approach is used for the curvature and torsion calculation of the discrete contour in a 3-D space. Finally, a method is developed for detecting feature points of the fragment contour based on total curvature. Therefore, the contour description combines the simple global information with local feature points. Experiments with real contour curves extracted from 3-D fragments demonstrate that the proposed method is robust and efficient.

Automatic determination method of optimal threshold based on the bootstrapping technology

In order to predict the extreme load of the mechanical components during the entire life,an automatic method based on the bootstrapping technology(BT)is proposed to determine the most suitable threshold.Based on all the turning points of the load history and a series of thresholds estimated in advance,the generalized Pareto distribution is established to fit the exceedances.The corresponding distribution parameters are estimated with the maximum likelihood method.Then,BT is employed to calculate the mean squared error(MSE)of each estimated threshold based on the exceedances and the specific distribution parameters.Finally,the threshold with the smallest MSE will be the optimal one.Compared to the kurtosis method and the mean excess function method,the average deviation of the probability density function of exceedances determined by BT reduces by 38.52%and 29.25%,respectively.Moreover,the quantile-quantile plot of the exceedances determined by BT is closer to a straight line.The results suggest the improvement of the modeling flexibility and the determined threshold precision.If the exceedances are insufficient,BT will enlarge their amount by resampling to solve the instability problem of the original distribution parameters.

Solid phase microextraction(SPME) sampling under turbulent conditions and for the simultaneous collecting of tracer gases

Solid phase microextraction （SPME） is a solvent-flee method of sample collection. SPME is an appealing method for sample collection because it is designed for the sampling of trace level analytes with short sampling times in a variety of environments. Additionally, SPME can be used to directly deliver a sample to a gas chromatograph （GC） for analysis by means of thermal desorption. In this paper, the performance of SPME under dynamic conditions was investigated. Additionally, the competence of SPME sampling for the simultaneous analysis of multiple trace analytes was also evaluated. This work is discussed in the context of underground mine ventilation surveys but is applicable to any industry in which ventilation circuits must be evaluated. The results of this paper showed that the performance of the 100 ~m PDMS SPME fiber was both precise and rapid under dynamic conditions. This SPME fiber was also able to simultaneously collect sulfur hexafluoride （SF6） and perfluoromethylcyclohexane （PMCH） with adequate sensitivity.

An EMD based method for detrending RR interval series without resampling

Slow trends in the RR interval(RRI) series should be removed in the preprocessing step to get a reliable result of heart rate variability(HRV) analysis. Re-sampling is required to convert the unevenly sampled RRI series into evenly sampled time series when using the widely accepted smoothness priors approach(SPA). Noise is introduced in this process and the information quality is thus compromised. Empirical mode decomposition(EMD) and its variants, were introduced to directly process the unevenly sampled RRI series. Besides, a RR interval model was proposed to fascinate the introduction of standard metrics for the evaluation of the detrending performance. Based on standard metrics including signal-to-noise-ratio in d B(ISNR), mean square error(EMS), and percent root square difference(DPRS), the effectiveness of detrending methods in RR interval analysis were determined. Results demonstrate that complementary ensemble EMD(CEEMD, a variant of EMD) based method has a higher ISNR, a lower EMS and a lower DPRS as well as a better RRI series detrending performance compared with the SPA method, which would in turn lead to a more accurate HRV analysis.

Interest Rate Statistics in Nigeria： Its Sampling Techniques and Computational Procedures

Developing nations, like Nigeria, whose financial systems and infrastructural base are not yet fully developed face data rendition challenges which may hamper the representativeness of their interest rate statistics.A critical component of any credible interest rate data compilation framework relates to the sampling procedure.In Nigeria, no work has been done with regards to employing alternatives sampling techniques in the computation of interest rate statistics largely because of the small number of deposit money banks in the country. Leveraging on existing literature and established statistical methods, the study examines two sampling techniques for generating credible and reliable interest rates in Nigeria. The current interest rate compilation framework in the country is presented and alternative sampling procedures were explored with a view to investigating their appropriateness for Nigeria＇s interest rate computation. The interest rates generated based on the current population-based compilation method is compared with those of the alternative approaches. This paper recommends the use of purposive sampling method that covers Deposit Money Banks （DMBs） which account for about 70.0 per cent of the banking sector total assets as an appropriatealternative.

Design of a sinc-sampled fiber Bragg grating fabricated in high birefringence fiber

In this paper we design a new kind of sinc-sampled fiber Bragg grating which is fabricated in high birefringence fiber (HBF). The sampled grating has two sets of reflection spectra along two perpendicular polarization directions. The grating's channel number can be doubled approximately by designing the refractive index difference between the fast and slow axes of the fiber, which enhances the utilization ratio and reduces the claim for photosensitivity of the fiber. The group delay characteristics are theoretically studied and side-lobes are depressed by apodization as well to get the optimized spectra. The results show that the comb-like spectra of the grating have promising applications in both multi-wavelength polarized fiber lasers and fiber sensing networks.