Numerical Prediction Methods for Clock Deviation Based on Two-Way Satellite Time and Frequency Transfer Data

Three functional models, polynomial, spectral analysis, and modified AR model, are studied and compared in fitting and predicting clock deviation based on the data sequence derived from two-way satellite time and frequency transfer. A robust equivalent weight is applied, which controls the significant influence of outlying observations. Some conclusions show that the prediction precision of robust estimation is better than that of LS. The prediction precision calculated from smoothed observations is higher than that calculated from sampling observations. As a count of the obvious period variations in the clock deviation sequence, the predicted values of polynomial model are implausible. The prediction precision of spectral analysis model is very low, but the principal periods can be determined. The prediction RMS of 6-hour extrapolation interval is Ins or so, when modified AR model is used.

Comparison of time optimal control for two level quantum systems

The time optimal problem for a two level quantum sys-tem is studied. We compare two different control strategies of bang-bang control and the geometric control, respectively, es-pecial y in the case of minimizing the time of steering the state from North Pole to South Pole on the Bloch sphere with bounded control. The time performances are compared for different param-eters by the individual numerical simulation experiments, and the experimental results are analyzed. The results show that the ge-ometric control spends less time than the bang-bang control does.

Technology of shipboard two-way microwave time synchronization

For the high precision time synchronization demand of ships, advantages and disadvantages of the present time transfer methods are analyzed, the two-way microwave time transfer （TWMTT） method is adopted to resolve the time synchronization problem in the Naval Ship Formation. After expounding the principle and system composition of TWMTT method, the various factors influencing the synchronous precision are analyzed, such as time-interval measurement error, TWMTT equipment delay error, signal propagation error in air, and signal delay error caused by shipping. To improve the time synchronization precision, all the error sources above are deduced with mathematical measures to definite the critical one, and the signal processing measures such as Pseudo code spread spectrum time comparison signal generation technology, FFT fast acquisition technology and precise tracking technology are used into the modem which is the core equipment of the TWMTT. And, calibration method of TWMTT equipment delay are developed. Through theoretical a- nalysis and simulation verification, the precision of shipboard two-way microwave time synchroniza- tion can reach 1 ns.

ICON/MIGHTI与TIMED/SABER探测温度数据的对比

ICON卫星为临近空间环境特性研究、建模和预报提供了新数据.通过对ICON/MIGHTI与TIMED/SABER在90~105 km高度探测温度数据的比较,计算两者的年平均温度偏差和均方根误差,同时分析月平均温度偏差在不同月份中随高度和纬度的分布情况,为MIGHTI和SABER温度探测数据在临近空间大气建模和预报应用提供参考依据.结果表明,MIGHTI和SABER的温度垂直廓线变化趋势基本吻合,数值上有所差异.在12°S-42°N范围内,MIGHTI探测温度与SABER相比,在90~93 km时偏低,偏差最大值约2.5 K,在93~105 km偏高,偏差的绝对值最大约10 K.在不同季节,白天的温度偏差通常高于夜晚.SABER和MIGHTI的月平均温度偏差随季节和纬度的变化显著,夏季时的月平均温度偏差最大,且温度的均方根误差最大.

Comparison of the level of thrombus precursor protein in blood plasma between patients with acute cerebral infarction and healthy persons at different time

BACKGROUND： Thrombus precursor protein （TpP） is the index of thrombus activity level, and it is also early referencing index in detecting thrombus diseases. OBJECTIVE： To dynamically observe the changes of TpP level in blood plasma of patients with acute cerebral infarction at different time after onset, and to compare the differences of plasma TpP level between patients with acute cerebral infarction and healthy persons who received health examination. DESIGN： Controlled observation SETTING： Department of Neurology, Affiliated Hospital of Xuzhou Medical College PARTICIPANTS： Totally 58 patients with acute cerebral infarction who received the treatment in the Department of Neurology, Affiliated Hospital of Xuzhou Medical College between September 2004 and March 2005 were recruited in this study. They all met the diagnostic criteria revised by the 4^th National Conference of Cerebrovascular Disorders in 1995 and were diagnosed by clinical and skull CT and （or） MRI examinations. The patients included 33 male and 25 female aged from 36 to 87 years. Time to onset 〈 6 hours, 6 to 11 hours, 12 to 23 hours, 24 to 48 hours and 〉 48 hours were found in 10,11,14,10 and 13 patients respectively. Another 51 persons who homeochronously received the health body examination in our hospital were recruited, including 34 male and 17 female, aged 38 to 85 years, serving as control group. Patients with cardio-cerebrovascualr diseases or liver and kidney diseases were excluded. All the involved subjects were informed of the detected items. METHODS： About 4 mL venous blood was respectively taken from patients admitted to the hospital within 6 hours, 6 toll hours, 12 to 23 hours, 24 to 48 hours and more then 48 hours after onset, and healthy persons when receiving health examination. The level of TpP in blood plasma was measured with enzymelinked immunosorbent assay. MAIN OUTCOME MEASURES： ① Comparison of the level of plasma TpP between patients and controls;② Comparison of the level of plasma TpP of patients with acute cerebral infarction at different time after onset. RESULTS： Totally 58 patients with acute cerebral infarction and 51 persons who received health examination participated in the result analysis. ①Comparison of plasma TpP level between patients and controls： The plasma TpP level of patients with acute cerebral infarction was significantly higher than that of control group [（16.12±3.28）vs （5.38±1.36） mg/L, t= 20.993, P〈 0.01 ]. ② Comparison of plasma TpP level of patients with acute cerebral infarction at different time after onset： The level of plasma TpP was （12.06±3.06） mg/L within 6 hours, （15.11±3.42） mg/L at 6 to 11 hours, （20.63±4.05） mg/L at 12 to 23 hours, （16.15±3.50） mg/L at 24 to 48 hours and （11.88±3.11） mg/L at more than 48 hours after onset. It increased from the 6^th hour, reached the peak at the 12^th to 23^rd hours, maintained at very high level at the 48= hour and then gradually decreased and recovered to the level within 6 hours after onset. The level of plasma TpP of patients with acute cerebral infarction was signiticantly higher at the 12^th to 23^rd hours after onset and the 24^th to 48^th hours after onset than within 6 hours after onset （t = 13.385, P 〈 0.05）. CONCLUSION： ①The level of plasma TpP of patients with acute cerebral infarction is significantly higher than that of persons who received health examination.② Plasma TpP levels of patients with acute cerebral infarction change in wave manner at the different time after onset.

A Comparison of Floating Car vs.Loop Detector Estimated Freeway Travel Time Delay

Floating car-and loop detector-based methods are two different types of methods frequently used to collect travel time delay information across a freeway network.Sometimes,it is necessary to use them jointly to achieve the necessary freeway network coverage,due to the high labor costs for the floating car-based method and the indispensability of sufficient network instrumentation for the loop detector-based method.For example,both floating car-and loop detector-based methods were once used in the Highway Congestion Monitoring Program in the California Department of Transportation.It is therefore necessary to evaluate whether these two types of methods estimate similarly in terms of total travel time delay.To this end,corresponding delay information estimated using both types of methods from 37 freeway segments in the Greater Sacramento Area were collected and compared.It was found that these two types of methods do not estimate similarly in terms of total segment travel time delay.The mean absolute relative difference(MARD)can be as high as 78%,especially when delay is defined using a lower reference speed,such as 56 km/h.However,in terms of total segment travel time,the loop detector and the modified floating car method estimated similarly.The MARD is 19%.It was also found that the estimation from the different methods did correlate fairly well,which provides a means of conversion when different methods are used to monitor the total delay across a freeway network.As a spin-off,it was also found that a 1.5 km spacing of loop detectors is sufficient to achieve the 19%MARD as compared with the modified floating car method in terms of total travel time estimation.

MicrobMatcher: a microbial comparison software based on matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry

Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how to compare unknown strains to the known one quickly, semi-automatically and accurately. In this paper, we present a software tool that allows flexibly microbial matching in a user-friendly way, by letting the users to customize comparison parameters including: in vitro transcription enzyme, mass tolerance,minimum fragment length, intensity threshold and corresponding weights. We provide three spectral scoring functions to compute the affin-ity between the species. Therefore, the precision of microbial comparison increases. To test and verify this tool, we employed experimental spectral data based on MALDI-TOFMS and the gene sequences of E.coli and Salmonella. This software is written in Java for cross-platform intention.

COSMIC大气掩星与SABER/TIMED探测温度数据比较

本文利用2009年1月—2011年12月共3年的COSMIC大气掩星观测数据与SABER/TIMED探测数据开展15～60km大气温度数据的比较分析研究,计算COSMIC与SABER/TIMED探测温度的绝对偏差(TSABER-TCOSMIC),并统计其平均温度偏差和标准偏差,分析温度偏差随高度、纬度和季节的分布特征,为COSMIC大气掩星与SABER/TIMED探测数据的应用提供更多的参考依据.结果表明:COSMIC与SABER/TIMED数据所反映的温度随高度的变化特征是一致的,数据的大体趋势吻合较好.全球范围的平均温度偏差在38km左右接近于0K,在38km以上,平均温度偏差表现为负的系统性偏差,且随着高度逐渐增大,在38km以下,平均温度偏差表现为正的系统性偏差,在23km左右存在极大值,约为2.7K.COSMIC与SABER/TIMED温度偏差的分布存在着随纬度和季节的变化特征,35km以下,平均温度偏差在高纬地区和冬季较小,低纬地区和夏季较大,35km以上,平均温度偏差在高纬地区和冬季较大,低纬地区和夏季较小.温度偏差的标准偏差在低纬地区和夏季较小,高纬地区和冬季较大.纬圈平均的温度偏差在南北半球的分布基本呈对称结构.

一种采用斜波比较的精细步进延时系统

为了实现高频信号在欠采样条件下的波形重构,步进延迟脉冲信号的产生成为顺序等效时间采样技术用于触发取样系统进行高频信号采样的关键。为此,对精细延时方法进行研究,采用斜波比较的方法设计了一种精细步进延时系统,该系统基于微波三极管的开关特性,结合恒流源、充放电电路、高速电压比较器以及可编程DAC产生可调步进延迟时间的触发序列。对该系统进行仿真分析以及实验测试。实验结果表明,电容放电的线性区域下降沿时间为10 ns,幅度为4~7 V,与DAC比较后输出延迟脉冲的步进范围为10 ns,单位步进延迟精度可达1 ps。该斜波比较精细步进延迟系统可应用于取样示波器、矢量网络分析仪等测试仪器中,实现通信、雷达等信号探测与分析,对于高频信号的获取与分析具有重要意义。

XG7050型与TimeAcc007型时间综合测试仪的比较分析

针对时间综合测试仪在时间频率领域的测量性能,分析比较XG7050型与Time Acc007型精密时间综合测试仪在基本功能、接口、测量精度以及操作各方面的不同,为用户在不同测量条件下选择合适的时间综合测试仪提供参考。

MULTI-DIMENSIONAL REFLECTED BACKWARD STOCHASTIC DIFFERENTIAL EQUATIONS AND THE COMPARISON THEOREM

In this article, we study the multi-dimensional reflected backward stochastic differential equations. The existence and uniqueness result of the solution for this kind of equation is proved by the fixed point argument where every element of the solution is forced to stay above the given stochastic process, i.e., multi-dimensional obstacle, respectively. We also give a kind of multi-dimensional comparison theorem for the reflected BSDE and then use it as the tool to prove an existence result for the multi-dimensional reflected BSDE where the coefficient is continuous and has linear growth.

FORWARD-BACKWARD STOCHASTIC DIFFERENTIAL EQUATIONS WITH STOPPING TIME

The existence and uniqueness results of fully coupled forward-backward stochastic differential equations with stopping time (unbounded) is obtained. One kind of comparison theorem for this kind of equations is also proved.

Performance of real‑time neutron/gamma discrimination methods

Nuclear security usually requires the simultaneous detection of neutrons and gamma rays.With the development of crystalline materials in recent years,Cs2LiLaBr6(CLLB)dual-readout detectors have attracted extensive attention from researchers,where real-time neutron/gamma pulse discrimination is the critical factor among detector performance parameters.This study investigated the discrimination performance of the charge comparison,amplitude comparison,time comparison,and pulse gradient_(m)ethods and the effects of a Sallen–Key filter on their performance.Experimental results show that the figure of merit(FOM)of all four methods is improved by proper filtering.Among them,the charge comparison method exhibits excellent noise resistance;moreover,it is the most_(s)uitable method of real-time discrimination for CLLB detectors.However,its discrimination performance depends on the parameters t_(s),t_(m),and t_(e).When t_(s)corresponds to the moment at which the pulse is at 10%of its peak value,t_(e)requires a delay of only 640–740 ns compared to t_(s),at which time the potentially optimal FOM of the charge comparison method at 3.1–3.3 MeV is greater than 1.46.The FOM obtained using the t_(m)value calculated by a proposed maximized discrimination difference model(MDDM)and the potentially optimal FOM differ by less than 3.9%,indicating that the model can provide good guidance for parameter selection in the charge comparison method.

A Comparison Theorem for Solution of the Fully Coupled Backward Stochastic Differential Equations

The comparison theorems of solutions for BSDEs in fully coupled forward-backward stochastic differential equations (FBSDEs) are studied in this paper, here in the fully coupled FBSDEs the forward SDEs are the same structure.

Boundary-Based Time Series Sorting

In many applications, it is desirable to sort the data. Most of previous work on sorting are key based, however, there are no apparent keys for the time-series data and therefore the classic sorting algorithms may fail in sorting time-series data. We propose a novel technique, called TS-Sort, to sort time-series sequences in the massive set. The proposed method first extracts the maximum and minimum boundaries of the set, then calculates the distance values between the sequences to the boundaries, and finally sorts the values to determine the relative orders of sequences in the set. For improvement, we propose a partition based version of the algorithm, which puts the sequences into small groups, and sorts the groups to get the final sorted set. Extensive experiments, both on synthetic and real datasets, show that our approach can be used to make the time series set in order, and there is a factor of up to 26.3% accelerating for the improved version of the method.

A Study on Applications and Case Studies Regarding Bluetooth Technology for Travel Time Measurement

Bluetooth technology emerged over twenty years ago and has continuously improved throughout the years to meet diverse and complex applications. Initially invented to replace the need for physical data cables, Bluetooth offers users a quick and easy way to share data files over a wireless network. Traffic engineers and transportation engineering researchers have utilized the potential opportunities that exist with Bluetooth and have implemented this technology into traffic monitoring techniques. To gain a better understanding of Bluetooth sensors and how they work, a comprehensive literature search was conducted. Twenty-five articles were studied regarding case studies of Bluetooth sensor implementation for travel time measurement. Besides reviewing the literature and previous case studies, three new case studies in the State of Delaware, USA, were also conducted and carefully analyzed. The benefits and drawbacks associated with Bluetooth technology for travel time measurements have been identified in this paper. The overall conclusion of the authors is Bluetooth alone and by itself is not a proper technology for travel time measurements. More studies need to be conducted on the accuracy and overall application, before one can confidently utilize the Bluetooth technology for travel time measurements.

Strong-Stability-Preserving, K-Step, 5- to 10-Stage, Hermite-Birkhoff Time-Discretizations of Order 12

We construct optimal k-step, 5- to 10-stage, explicit, strong-stability-preserving Hermite-Birkhoff (SSP HB) methods of order 12 with nonnegative coefficients by combining linear k-step methods of order 9 with 5- to 10-stage Runge-Kutta (RK) methods of order 4. Since these methods maintain the monotonicity property, they are well suited for solving hyperbolic PDEs by the method of lines after a spatial discretization. It is seen that the 8-step 7-stage HB methods have largest effective SSP coefficient among the HB methods of order 12 on hand. On Burgers’ equations, some of the new HB methods have larger maximum effective CFL numbers than Huang’s 7-step hybrid method of order 7, thus allowing larger step size.

Analog rise-time discriminator for CdZnTe detector

Due to variable time for charge collection,energy resolution of nuclear detectors declines,especially compound semiconductor detectors like cadmium zinc telluride(CdZnTe) detector.To solve this problem,an analog rise-time discriminator based on charge comparison principle is designed.The reference charge signal after attenuation is compared with the deconvoluted and delayed current signal.It is found that the amplitude of delayed current signal is higher than that of the reference charge signal when rise time of the input signal is shorter than the discrimination time,thus generating gating signal and triggering DMCA(digital multi-channel analyzer) to receive the total integral charge signal.When rise time of the input signal is longer than discrimination time,DMCA remains inactivated and the corresponding total integral charge signal is abandoned.Test results show that combination of the designed rise-time discriminator and DMCA can reduce hole tailing of CdZnTe detector significantly.Energy resolution of the system is 0.98%@662 keV,and it is still excellent under high counting rates.

可级联组网的无线时间比对系统设计

随着科技的发展,越来越多的场合需要实现多个终端间的纳秒量级高精度时间比对,例如现代化军事靶场、战场、雷达观测基地等。现阶段常用的纳秒量级多终端间的时间比对方法是导航卫星共视法,该方法需要搭建数据交换链路,应用的灵活性受限。本文基于无线伪随机码测距原理、双向时间比对原理和码分多址技术,设计出一套可以自适应组网的高精度时间比对系统,不需要额外搭建数据交互通路即可实现级联节点之间的纳秒量级时间比对。其次,分析了利用该系统实现纳秒量级时间比对的技术难点,并提出了相应的解决方法。最后,搭建实验平台对设计的时间比对系统进行验证。实验结果表明,在500 m的无线比对基线下,可以实现优于0.5 ns的静态时间比对精度。

Relativistic Reduction of the Electron-Nucleus Force in Bohr’s Hydrogen Atom and the Time of Electron Transition between the Neighbouring Quantum Energy Levels

The aim of the paper is to get an insight into the time interval of electron emission done between two neighbouring energy levels of the hydrogen atom. To this purpose, in the first step, the formulae of the special relativity are applied to demonstrate the conditions which can annihilate the electrostatic force acting between the nucleus and electron in the atom. This result is obtained when a suitable electron speed entering the Lorentz transformation is combined with the strength of the magnetic field acting normally to the electron orbit in the atom. In the next step, the Maxwell equation characterizing the electromotive force is applied to calculate the time interval connected with the change of the magnetic field necessary to produce the force. It is shown that the time interval obtained from the Maxwell equation, multiplied by the energy change of two neighbouring energy levels considered in the atom, does satisfy the Joule-Lenz formula associated with the quantum electron energy emission rate between the levels.