大规模网络流量数据异常快速检测研究

在大规模网络流量环境下,由于传统的网络流量数据异常检测方法对于异常特征的识别效果不佳,影响了网络流量异常数据检测的准确率,研究一种新的大规模网络流量数据异常快速检测方法。通过设定采集时间间隔,实时记录数据并存储在数据库中,便于数据读取,实现大规模网络流量数据采集。根据数据采集结果,提取网络流量异常特征,计算异常特征序列信息熵,去除网络流量数据的冗余特征。根据特征提取结果建立网络流量数据异常快速检测模型,判断网络流量中是否存在异常数据,实现大规模网络流量数据异常快速检测。在实验过程中将该文方法与传统方法1和传统方法2进行对比,该方法在不同数据个数情况下的检测准确率均在90%以上,在不同流量异常数据类别条件下的漏检率最低,且运行耗时短,证明该方法可以精准检测大规模网络流量数据异常。

多路阀阀芯拓扑形态设计的流量数参数模型

为避免多路阀阀芯拓扑形态设计中满足多种复杂载荷条件的计算流体力学(computational fluid dynamics,CFD)仿真的庞大计算量,提出了多路阀阀芯拓扑形态设计的流量数参数模型。由于多路阀常处于饱和流量状态,故假设流量系数仅与阀芯拓扑形态和阀芯位移有关,用流量数作为表达节流槽流量控制特性的参数。首先,通过有限变量空间中的CFD仿真样本,运用统计学方法建立不同节流槽结构的流量数参数模型。然后,通过线性叠加得到阀口的流量数参数模型。最后,以20吨级液压挖掘机多路阀为研究对象,使用流量数参数模型实现了一定载荷特征与性能要求下的多路阀节流结构定制化设计。研究结果表明,流量数参数模型对复杂载荷条件下多路阀阀芯拓扑形态设计具有良好的设计精度与简便性。

变流量数燃油喷嘴动态模拟装置及控制方法

提出一种变流量数燃油喷嘴动态模拟装置。采用伺服电机驱动的调节阀、压力传感器、流量计等组成装置硬件。在分析真实喷嘴动力学模型的基础上,提出压差动力控制法,实现3组并联变流量数喷嘴的流量特性模拟。对模拟装置进行建模,分析其对流量突变、分配比突变等外界条件变化的响应。最后,通过实物样机验证可知,它在多喷嘴并联条件下可稳定运行,在总流量、分配比等外部条件变化时可快速响应与收敛。

网络流量异常检测中的维数约简研究

对包含大流量数据的高维度网络进行异常检测,必须加入维数约简处理以减轻系统在传输和存储方面的压力。介绍高速网络环境下网络流量异常检测过程以及维数约简方式,阐述流量数据常用特征和维数约简技术研究的最新进展。针对网络流量特征选择和流量特征提取2种特征降维方式,对现有算法进行归纳分类,分别描述算法原理及优缺点。此外,给出维数约简常用的数据集和评价指标,分析网络流量异常检测中维数约简技术研究面临的挑战,并对未来发展方向进行展望。

超声波流量计零流量漂数问题分析与抑制措施

针对超声波流量计小流量切除值无法满足计量撬热备路零流量漂数问题,采用因果链法分析影响流量计零流量漂数危害因素,应用Ensuite软件开展流量计算机启停遥控点位、PCS手动启停与计量状态反馈、GCScontri编写程序逻辑组态,建立三者之间的手/自动连锁控制逻辑。结果表明,流量计算机本体组态不完善为流量计零流量漂数累计终极因素;研究方法可有效消除场站停输工况下的零流量漂数累计问题;方法的实现一定程度可免去流量计对小流量切除值设定的需求,规避了当前规范标准对小流量切除值设定不明确的弊端。研究可为实现精准计量、消除计量交接贸易分歧提供有益参考。

基于流场仿真的滑阀节流口流量特性研究

滑阀阀芯处的节流口是应用最为广泛的一种液压元件结构,其流量控制特性常常用流量系数描述。由于流量系数随着节流口开度的变化会出现较大的、无规律的波动,使用起来很不方便,为此提出了"流量数"的概念,用其代替节流口流量系数与过流面积乘积。流量数的数值虽然也随着节流口开度的变化而变化,却具有良好的连续性,易于进行节流口流量特性的研究。该研究利用Fluent仿真软件,对多种典型阀芯的节流口流量数进行了计算,得到了流量数具有平滑、连续性变化的特点,并通过台架试验验证了仿真结果的正确性。为了得出节流口尺寸与流量数的对应关系,更好地设计出理想的节流阀口,提出了基于多维插值方法获得流量数的实现途径,并以U形节流口为例,进行了仿真验证。

小汽轮机高参数化下的参数及热力方案选择研究

基于热力学原理推导了汽轮机实际循环效率与理想循环效率及内效率之间的关系,并推导了理想循环效率与主汽参数间的关系;提出了无量纲相对体积流量数的概念,对小体积流量进行定义与衡量,并采用小焓降级及高转速方案提高小体积流量级内效率。结果表明:综合考虑小汽轮机实际循环效率、安全及性价比,主汽温度宜采用535℃;基于主汽压力提高对内效率的负面影响,50 MW及以下等级汽轮机主汽压力不宜超过8.83 MPa,而采用一次再热配合双缸双转速方案,可将主汽压力提高至13.24 MPa,机组实际循环效率可最大提高15%左右。

基于计算机视觉的船舶流量计量的研究与应用

船舶交通流量是通过某一水域上下游的船舶数量,是表征航道交通状况和利用率的基本量,也是航道建设发展和航道经济价值评估的重要参考数据。采用了基于YOLO v3的实时目标检测技术,同时利用Sort目标追踪算法,使用标记线的方式,实现了对内河船舶目标快速、准确的检测和航道上下游流量的统计。

多喷嘴对置式水煤浆气化装置氧气流量温压补偿方案分析

多喷嘴对置式水煤浆气化装置每台气化炉涉及到多条氧气管线,合理地设置氧气流量温压补偿测点,能有效地避免因补偿测点仪表故障而对本台气化炉及多台气化炉的安全、稳定运行造成影响。在DCS系统中氧煤比的控制非常重要,在ESD系统中氧气流量参与烧嘴的三选二联锁跳车,因此氧气流量示数是否准确非常重要。结合工程实际,分析与总结早期工程设计中氧气流量温压补偿方案以及之后工程应用中氧气流量温压补偿优化方案的优缺点,在此基础上提出一种新的氧气流量温压补偿改进方案。新的氧气流量温压补偿改进方案在不过多设置压力测点和温度测点的情况下,可保证氧气流量温压补偿的可靠性,且在多台气化炉运行的情况下其信号分配更合理,可降低因压力仪表或温度仪表故障给系统带来的影响。

A study of impact of the reclamation and artificial island projects on tidal currents and sediment concentration in radial sand ridge field of the South Yellow Sea

The two-dimensional hydrodynamic model, MIKE21, is applied to simulate the tidal currents and sediment concentration in the radial sand ridges of the South Yellow Sea. Results are in accordance with in situ observations. Then the variations of tidal currents and suspended sediment concentration caused by reclamation and artificial islands projects are simulated. The results show that the impacts are limited around the project areas. After the projects, the fan-shaped, Jianggang centered tidal current pattern would be replaced by a pattern which is formed by two tidal paths. One locates at the Xiyang channel in north-south direction, and the other locates at the Huangshayang channel in east-west direction. The reclamation of Tiaozini separates the waters into south portion and north portion. The changes of sediment concentrations coincide with those of currents. Both the sediment concentrations and tidal currents increase at the northwest of Dongsha and the south of Gaoni, while both decrease at the north and south of Tiaozini, and the east and southwest of Dongsha.

INTERNET TRAFFIC DATA FLOW FORECAST BY RBF NEURAL NETWORK BASED ON PHASE SPACE RECONSTRUCTION

Characteristics of the Internet traffic data flow are studied based on the chaos theory. A phase space that is isometric with the network dynamic system is reconstructed by using the single variable time series of a network flow. Some parameters, such as the correlative dimension and the Lyapunov exponent are calculated, and the chaos characteristic is proved to exist in Internet traffic data flows. A neural network model is construct- ed based on radial basis function （RBF） to forecast actual Internet traffic data flow. Simulation results show that, compared with other forecasts of the forward-feedback neural network, the forecast of the RBF neural network based on the chaos theory has faster learning capacity and higher forecasting accuracy.

Temperature Distribution in Ethylene Pyrolyzer

A good understanding of the detailed temperature distribution in the furnace plays an important role in the implementation of operation optimization and design improvement of ethylene pyrolyzer. Numerical simulation of the turbulent flow, combustion and heat transfer was carried out to investigate the temperature distribution in industrial furnace. Inhomogeneities of the flue-gas temperature distribution were observed in X, Y, and Z direction of the furnace from the simulated results. Along the height of the furnace, the average flue-gas temperature increased initially and decreased afterward, and reached its peak at the height of 5 m. The reactor tube skin temperature varied not only along the height of the furnace, but also around the circumference of the tube. The heat flux profiles from the furnace towards the reactor tubes followed the shape of the average flue-gas temperature profile. The heat flux of the inlet tubes was constantly higher than that of the outlet tubes at the same height in the furnace.

Effects of slope gradient on runoff from bare-fallow purple soil in China under natural rainfall conditions

Purple soil is highly susceptible for overland flow and surface erosion, therefore understanding surface runoff and soil erosion processes in the purple soil region are important to mitigate flooding and erosion hazards. Slope angle is an important parameter that affects the magnitude of runoff and thus surface erosion in hilly landscapes or bare land area. However, the effect of slope on runoff generation remains unclear in many different soils including Chinese purple soil. The aim of this study was to investigate the relationship between different slope gradients and surface runoff for bare-fallow purple soil, using 5 m × 1.5 m experimental plots under natural rainfall conditions. Four experimental plots(10°, 16°, 20° and 26°) were established in theYanting Agro-ecological Experimental Station of Chinese Academy of Science in central Sichuan Basin. The plot was equipped with water storage tank to monitor water level change. Field monitoring from July 1 to October 31, 2012 observed 42 rainfall events which produced surface runoff from the experimental plots. These water level changes were converted to runoff. The representative eight rainfall events were selected for further analysis, the relationship between slope and runoff coefficient were determined using ANOVA, F-test, and z-score analysis. The results indicated a strong correlation between rainfall and runoff in cumulative amount basis. The mean value of the measured runoff coefficient for four experimental plots was around 0.1. However, no statistically significant relationship was found between slope and runoff coefficient. We reviewed the relationship between slope and runoff in many previous studiesand calculated z-score to compare with our experimental results. The results of z-score analysis indicated that both positive and negative effects of slope on runoff coefficient were obtained, however a moderate gradient(16°-20° in this study) could be a threshold of runoff generation for many different soils including the Chinese purple soil.

Propagation law of shock waves and gas flow in cross roadway caused by coal and gas outburst

In order to study the propagation law of shock waves and gas flow during coal and gas outburst,we analyzed the formation process of outburst shock waves and gas flow and established the numerical simulation models of the roadways with 45°intersection and 135°intersection to simulate the propagation of outburst gas flow and the process of gas transport.Based on the analysis of the simulation results,we obtained the qualitative and quantitative conclusions on the characteristics and patterns of propagation and attenuation of outburst shock waves and gas flow.With the experimental models,we investigated the outburst shock waves and gas flow in the roadways with the similar structures to the simulated ones.According to the simulation results,when the angle between the driving roadway and the adjacent roadway increased,the sudden pressure variation range in adjacent roadway and the influencing scope of gas flow increased and the sudden pressure variation duration decreased.The intersection between the driving roadway and the adjacent roadway has no effect on airflow reversal induced by the shock waves and gas flow.

Oil–water two-phase flow pattern analysis with ERT based measurement and multivariate maximum Lyapunov exponent

Oil–water two-phase flow patterns in a horizontal pipe are analyzed with a 16-electrode electrical resistance tomography(ERT) system. The measurement data of the ERT are treated as a multivariate time-series, thus the information extracted from each electrode represents the local phase distribution and fraction change at that location. The multivariate maximum Lyapunov exponent(MMLE) is extracted from the 16-dimension time-series to demonstrate the change of flow pattern versus the superficial velocity ratio of oil to water. The correlation dimension of the multivariate time-series is further introduced to jointly characterize and finally separate the flow patterns with MMLE. The change of flow patterns with superficial oil velocity at different water superficial velocities is studied with MMLE and correlation dimension, respectively, and the flow pattern transition can also be characterized with these two features. The proposed MMLE and correlation dimension map could effectively separate the flow patterns, thus is an effective tool for flow pattern identification and transition analysis.

Impact of body mass index and gender on quality of life in patients with gastroesophageal reflux disease

AIM： To investigate the symptom presentation and quality of life in obese Chinese patients with gastro- esophageal reflux disease （GERD）. MKTHODS： Data from patients diagnosed with GERD according to the Montreal definition, were collected between January 2009 to March 2010. The enrolled patients were assigned to the normal [body mass in- dex （BMI） 〈 25 kg/m2], overweight （25-30 kg/m2）, and obese （BMI 〉 30 kg/m2） groups. General demographic data, endoscopic findings, and quality of life of the three groups of patients were analyzed and compared.and 15 patients were classified in the normal, over- weight, and obese, respectively. There was significantly more erosive esophagitis （73.3% vs 64.3% vs 39.2%, P = 0.002）, hiatal hernia （60% vs 33.9% vs 16.7%, P = 0.001）, and males （73.3% vs 73.2% vs 32.4%, P = 0.001） in the obese cases. The severity and frequency of heartburn, not acid regurgitation, was positively cor- related with BMI, with a significant association in men, but not in women. Obese patients were prone to have low quality of life scores, with obese women having the lowest scores for mental health. CONCLUSION： In patients with GERD, obese men had the most severe endoscopic and clinical presenta- tion. Obese women had the poorest mental health.

Effect of plunger number on hydraulic transformer's flow pulsation rate

In order to supply theoretical guidance to hydraulic transformer's design and application,the effect of the number of plungers in hydraulic transformer on its flow characteristic is analyzed,theoretical analysis and simulation are done on hydraulic transformer's flow characteristic when the number of plungers is different.Based on the working principle of swash plate piston hydraulic components,mathematical models of instantaneous flow and flow pulsation rate are built,and simulation study is done with MATLAB.As a result,the effect is found,and some conclusions worth referring to are obtained.

Exploratory study of logistics service quality scale based on online shopping malls

Online shopping has already become the new mode that a lot of customers try to adopt. At the same time, the online shopping could not be successfully completed without logistics service. Logistics service quality (LSQ) has significant impact on revenue and profitability. This paper presents the issue from the perspective of the customer, and explores the initial factors of LSQ based on the online shopping through in-depth interview and the Delphi method. The survey uses a standard 7-point Likert-type scale to measure the LSQ. Empirical research results are shown in detail to confirm seven LSQ dimensions with Chinese characteristics, including timeliness quality, personal contact quality, order quality, order discrepancy handling, order condition and convenience. Statistical analyses of the investigation were conducted to test the reliability and validity of the LSQ evaluation model.

An automatic identification algorithm for freeway bottleneck based on loop detector data

A bottleneck automatic identification algorithm based on loop detector data is proposed. The proposed algorithm selects the critical flow rate as the trigger variable of the algorithm which is calculated by the road conditions the level of service and the proportion of trucks.The process of identification includes two parts. One is to identify the upstream of the bottleneck by comparing the distance between the current occupancy rate and the mean value of the occupancy rate and the variance of the occupancy rate.The other process is to identify the downstream of the bottleneck by calculating the difference of the upstream occupancy rate with that of the downstream.In addition the algorithm evaluation standards which are based on the time interval of the data the detection rate and the false alarm rate are discussed.The proposed algorithm is applied to detect the bottleneck locations in the Shanghai Inner Ring Viaduct Dabaishu-Guangzhong road section.The proposed method has a good performance in improving the accuracy and efficiency of bottleneck identification.

Analysis of Runoff in Ungauged Mountain Watersheds in Sichuan,China using Kinematic-wave-based GIUH Model

Floods are one of the most common natural hazards occurring all around the world.However,the knowledge of the origins of a food and its possible magnitude in a given region remains unclear yet.This lack of understanding is particularly acute in mountainous regions with large degrees in Sichuan Province,China,where runoff is seldom measured.The nature of streamflow in a region is related to the time and spatial distribution of rainfall quantity and watershed geomorphology.The geomorphologic characteristics are the channel network and surrounding landscape which transform the rainfall input into an output hydrograph at the outlet of the watershed.With the given geomorphologic properties of the watershed,theoretically the hydrological response function can be determined hydraulically without using any recorded data of past rainfall or runoff events.In this study,a kinematic-wave-based geomorphologic instantaneous unit hydrograph (KW-GIUH) model was adopted and verified to estimate runoff in ungauged areas.Two mountain watersheds,the Yingjing River watershed and Tianquan River watershed in Sichuan were selected as study sites.The geomorphologic factors of the two watersheds were obtained by using a digital elevation model (DEM) based on the topographic database obtained from the Shuttle Radar Topography Mission of US's NASA.The tests of the model on the two watersheds were performed both at gauged and ungauged sites.Comparison between the simulated and observed hydrographs for a number of rainstorms at the gauged sites indicated the potential of the KW-GIUH model as a useful tool for runoff analysis in these regions.Moreover,to simulate possible concentrated rainstorms that could result in serious flooding in these areas,synthetic rainfall hyetographs were adopted as input to the KW-GIUH model to obtain the flow hydrographs at two ungauged sites for different return period conditions.Hydroeconomic analysis can be performed in the future to select the optimum design return period for determining the flood control work.