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Evaluation of Arterial Signal Coordination with Commercial Connected Vehicle Data: Empirical Traffic Flow Visualization and Performance Measurement
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作者 Shoaib Mahmud Christopher M. Day 《Journal of Transportation Technologies》 2023年第3期327-352,共26页
Emerging connected vehicle (CV) data sets have recently become commercially available, enabling analysts to develop a variety of powerful performance measures without deploying any field infrastructure. This paper pre... Emerging connected vehicle (CV) data sets have recently become commercially available, enabling analysts to develop a variety of powerful performance measures without deploying any field infrastructure. This paper presents several tools using CV data to evaluate traffic progression quality along a signalized corridor. These include both performance measures for high-level analysis as well as visualizations to examine details of the coordinated operation. With the use of CV data, it is possible to assess not only the movement of traffic on the corridor but also to consider its origin-destination (O-D) path through the corridor. Results for the real-world operation of an eight-intersection signalized arterial are presented. A series of high-level performance measures are used to evaluate overall performance by time of day, with differing results by metric. Next, the details of the operation are examined with the use of two visualization tools: a cyclic time-space diagram (TSD) and an empirical platoon progression diagram (PPD). Comparing flow visualizations developed with different included O-D paths reveals several features, such as the presence of secondary and tertiary platoons on certain sections that cannot be seen when only end-to-end journeys are included. In addition, speed heat maps are generated, providing both speed performance along the corridor and locations and the extent of the queue. The proposed visualization tools portray the corridor’s performance holistically instead of combining individual signal performance metrics. The techniques exhibited in this study are compelling for identifying locations where engineering solutions such as access management or timing plan change are required. The recent progress in infrastructure-free sensing technology has significantly increased the scope of CV data-based traffic management systems, enhancing the significance of this study. The study demonstrates the utility of CV trajectory data for obtaining high-level details of the corridor performance as well as drilling down into the minute specifics. 展开更多
关键词 Traffic Signal Performance measures Vehicle Trajectory data Connected Vehicle data
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Direct Pointwise Comparison of FE Predictions to StereoDIC Measurements:Developments and Validation Using Double Edge-Notched Tensile Specimen
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作者 Troy Myers Michael A.Sutton +2 位作者 Hubert Schreier Alistair Tofts Sreehari Rajan Kattil 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第8期1263-1298,共36页
To compare finite element analysis(FEA)predictions and stereovision digital image correlation(StereoDIC)strain measurements at the same spatial positions throughout a region of interest,a field comparison procedure is... To compare finite element analysis(FEA)predictions and stereovision digital image correlation(StereoDIC)strain measurements at the same spatial positions throughout a region of interest,a field comparison procedure is developed.The procedure includes(a)conversion of the finite element data into a triangular mesh,(b)selection of a common coordinate system,(c)determination of the rigid body transformation to place both measurements and FEA data in the same system and(d)interpolation of the FEA nodal information to the same spatial locations as the StereoDIC measurements using barycentric coordinates.For an aluminum Al-6061 double edge notched tensile specimen,FEA results are obtained using both the von Mises isotropic yield criterion and Hill’s quadratic anisotropic yield criterion,with the unknown Hill model parameters determined using full-field specimen strain measurements for the nominally plane stress specimen.Using Hill’s quadratic anisotropic yield criterion,the point-by-point comparison of experimentally based full-field strains and stresses to finite element predictions are shown to be in excellent agreement,confirming the effectiveness of the field comparison process. 展开更多
关键词 StereoDIC spatial co-registration data transformation finite element simulations point-wise comparison of measurements and FEA predictions double edge notch specimen model validation
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Simulation of fire emergency evacuation in a large-passenger-flow subway station based on the on-site measured data of Shenzhen Metro
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作者 Hua Chen Chenyang Zhang +3 位作者 Jieyu Zhang Ya Shu Xinjian Qi Chaozhe Jiang 《Transportation Safety and Environment》 EI 2024年第1期47-55,共9页
Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway... Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway station,and the number of casualties and injuries during a fire emergency is substantial.In this paper,Pathfinder software and on-site measured data of Pingzhou station in Shenzhen(China)were utilized to simulate a fire emergency evacuation in a large-passenger-flow subway station.The Required Safe Egress Time(RSET),number of passengers and flow rates of stairs and escalators were analysed for three fire evacuation scenarios:train fire,platform fire and hall fire.The evacuation time of the train fire,which was 1173 s,was the longest,and 3621 occupants needed to evacuate when the train was fully loaded.Occupants could not complete the evacuation within 6 mins in all three fire evacuation scenarios,which does not meet the current standard requirements and codes.By changing the number of passengers and the number of stairs for evacuation,the flow rate capacity and evacuation time were explored,which have reference values for safety management and emergency evacuation plan optimization during peak hours of subway operation. 展开更多
关键词 fire emergency evacuation large-passenger-flow subway station on-site measured data PATHFINDER
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Recent progress in nuclear data measurement for ADS at IMP 被引量:4
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作者 Zhi-Qiang Chen 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第12期269-278,共10页
Recent progress in nuclear data measurement for ADS at Institute of Modern Physics is reviewed briefly.Based on the cooler storage ring of the Heavy Ion Research Facility in Lanzhou, nuclear data terminal was establis... Recent progress in nuclear data measurement for ADS at Institute of Modern Physics is reviewed briefly.Based on the cooler storage ring of the Heavy Ion Research Facility in Lanzhou, nuclear data terminal was established.The nuclear data measurement facility for the ADS spallation target has been constructed, which provides a very important platform for the experimental measurements of spallation reactions. A number of experiments have been conducted in the nuclear data terminal. A Neutron Time-of-Flight(NTOF)spectrometer was developed for the study of neutron production from spallation reactions related to the ADS project.The experiments of 400 MeV/u ^(16)O bombarded on a tungsten target were presented using a NTOF spectrometer.Neutron yields for 250 MeV protons incident on a thick grain-made tungsten target and a thick solid lead target have been measured using the water-bath neutron activation method. Spallation residual productions were studied by bombarding W and Pb targets with a 250 MeV proton beam using the neutron activation method. Benchmarking of evaluated nuclear data libraries was performed for D-T neutrons on ADS relevant materials by using the benchmark experimental facility at the China Institute of Atomic Energy. 展开更多
关键词 Accelerator-driven systems NUCLEAR data measurEMENT Neutron TIME-OF-FLIGHT spectrometer Integral experiment Evaluated NUCLEAR data
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Similarity measure design for high dimensional data 被引量:3
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作者 LEE Sang-hyuk YAN Sun +1 位作者 JEONG Yoon-su SHIN Seung-soo 《Journal of Central South University》 SCIE EI CAS 2014年第9期3534-3540,共7页
Information analysis of high dimensional data was carried out through similarity measure application. High dimensional data were considered as the a typical structure. Additionally, overlapped and non-overlapped data ... Information analysis of high dimensional data was carried out through similarity measure application. High dimensional data were considered as the a typical structure. Additionally, overlapped and non-overlapped data were introduced, and similarity measure analysis was also illustrated and compared with conventional similarity measure. As a result, overlapped data comparison was possible to present similarity with conventional similarity measure. Non-overlapped data similarity analysis provided the clue to solve the similarity of high dimensional data. Considering high dimensional data analysis was designed with consideration of neighborhoods information. Conservative and strict solutions were proposed. Proposed similarity measure was applied to express financial fraud among multi dimensional datasets. In illustrative example, financial fraud similarity with respect to age, gender, qualification and job was presented. And with the proposed similarity measure, high dimensional personal data were calculated to evaluate how similar to the financial fraud. Calculation results show that the actual fraud has rather high similarity measure compared to the average, from minimal 0.0609 to maximal 0.1667. 展开更多
关键词 high dimensional data similarity measure DIFFERENCE neighborhood information financial fraud
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Diverging Diamond Interchange Performance Measures Using Connected Vehicle Data 被引量:4
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作者 Enrique D. Saldivar-Carranza Howell Li Darcy M. Bullock 《Journal of Transportation Technologies》 2021年第4期628-643,共16页
Since the first Diverging Diamond Interchange (DDI) implementation in 2009, most of the performance studies developed for this type of interchange have been based on simulations and historical crash data, with a small... Since the first Diverging Diamond Interchange (DDI) implementation in 2009, most of the performance studies developed for this type of interchange have been based on simulations and historical crash data, with a small numbe<span style="font-family:Verdana;">r of studies using Automated Traffic Signal Performance Measures (ATS</span><span style="font-family:Verdana;">PM). Simulation models require considerable effort to collect volumes and to model actual controller operations. Safety studies based on historical crashes usually require from 3 to 5 years of data collection. ATSPMs rely on sensing equipment. This study describes the use of connected vehicle trajectory data to analyze the performance of a DDI located in the metropolitan area of Fort Wayne, IN. An extension of the Purdue Probe Diagram (PPD) is proposed to assess the levels of delay, progression, and saturation. Further, an additional PPD variation is presented that provides a convenient visualization to qualitatively understand progression patterns and to evaluate queue length for spillback in the critical interior crossover. Over 7000 trajectories and 130,000 GPS points were analyzed between the 7</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> and the 11</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> of June 2021 from 5:00 AM to 10:00 PM to estimate the DDI’s arrivals on green, level of service, split failures, and downstream blockage. Although this technique was demonstrated for weekdays, the ubiquity of connected vehicle data makes it very ea</span><span style="font-family:Verdana;">sy to adapt these techniques to analysis during special events, winter sto</span><span style="font-family:Verdana;">rms, and weekends. Furthermore, the methodologies presented in this paper can be applied by any agency wanting to assess the performance of any DDI in their jurisdiction.</span> 展开更多
关键词 Diverging Diamond Interchange Performance measures Connected Vehicle Big data
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Design of similarity measure for discrete data and application to multi-dimension 被引量:1
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作者 LEE Myeong-ho 魏荷 +2 位作者 LEE Sang-hyuk LEE Sang-min SHIN Seung-soo 《Journal of Central South University》 SCIE EI CAS 2013年第4期982-987,共6页
Similarity measure design for discrete data group was proposed. Similarity measure design for continuous membership function was also carried out. Proposed similarity measures were designed based on fuzzy number and d... Similarity measure design for discrete data group was proposed. Similarity measure design for continuous membership function was also carried out. Proposed similarity measures were designed based on fuzzy number and distance measure, and were proved. To calculate the degree of similarity of discrete data, relative degree between data and total distribution was obtained. Discrete data similarity measure was completed with combination of mentioned relative degrees. Power interconnected system with multi characteristics was considered to apply discrete similarity measure. Naturally, similarity measure was extended to multi-dimensional similarity measure case, and applied to bus clustering problem. 展开更多
关键词 similarity measure MULTI-DIMENSION discrete data relative degree power interconnected system
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Strategy for Data Stream Processing Based on Measurement Metadata: An Outpatient Monitoring Scenario 被引量:1
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作者 Mario Diván Luis Olsina Silvia Gordillo 《Journal of Software Engineering and Applications》 2011年第12期653-665,共13页
In this work we discuss SDSPbMM, an integrated Strategy for Data Stream Processing based on Measurement Metadata, applied to an outpatient monitoring scenario. The measures associated to the attributes of the patient ... In this work we discuss SDSPbMM, an integrated Strategy for Data Stream Processing based on Measurement Metadata, applied to an outpatient monitoring scenario. The measures associated to the attributes of the patient (entity) under monitoring, come from heterogeneous data sources as data streams, together with metadata associated with the formal definition of a measurement and evaluation project. Such metadata supports the patient analysis and monitoring in a more consistent way, facilitating for instance: i) The early detection of problems typical of data such as missing values, outliers, among others;and ii) The risk anticipation by means of on-line classification models adapted to the patient. We also performed a simulation using a prototype developed for outpatient monitoring, in order to analyze empirically processing times and variable scalability, which shed light on the feasibility of applying the prototype to real situations. In addition, we analyze statistically the results of the simulation, in order to detect the components which incorporate more variability to the system. 展开更多
关键词 measurEMENT data STREAM Processing C-INCAMI STATISTICAL Analysis
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Data Fusion Method for Manufacturing Measurement
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作者 GU Li-chen, ZHANG You-yun, QUO Da-mou (School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期266-,共1页
A data fusion method of online multisensors is prop os ed in this paper based on artificial neuron. First, the dynamic data fusion mode l on artificial neuron is built. Then the calibration of data fusion is discusse ... A data fusion method of online multisensors is prop os ed in this paper based on artificial neuron. First, the dynamic data fusion mode l on artificial neuron is built. Then the calibration of data fusion is discusse d with self-adaptive weighing technique. Finally performance of the method is d emonstrated by an online vibration measurement case. The results show that the f used data are more stable, sensitive, accurate, reliable than that of single sen sor data. 展开更多
关键词 multisensor measures artificial neuron data fus ion fusion system calibration
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Similarity measure design on overlapped and non-overlapped data
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作者 LEE Sang-hyuk SHIN Seung-soo 《Journal of Central South University》 SCIE EI CAS 2013年第9期2440-2446,共7页
Similarity measure design on non-overlapped data was carried out and compared with the case of overlapped data.Unconsistant feature of similarity on overlapped data to non-overlapped data was provided by example.By th... Similarity measure design on non-overlapped data was carried out and compared with the case of overlapped data.Unconsistant feature of similarity on overlapped data to non-overlapped data was provided by example.By the artificial data illustration,it was proved that the conventional similarity measure was not proper to calculate the similarity measure of the non-overlapped case.To overcome the unbalance problem,similarity measure on non-overlapped data was obtained by considering neighbor information.Hence,different approaches to design similarity measure were proposed and proved by consideration of neighbor information.With the example of artificial data,similarity measure calculation was carried out.Similarity measure extension to intuitionistic fuzzy sets(IFSs)containing uncertainty named hesitance was also followed. 展开更多
关键词 similarity measure overlapped data non-overlapped data intuitionistic data
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Orthogonal Series Estimation of Nonparametric Regression Measurement Error Models with Validation Data
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作者 Zanhua Yin 《Applied Mathematics》 2017年第12期1820-1831,共12页
In this article we study the estimation method of nonparametric regression measurement error model based on a validation data. The estimation procedures are based on orthogonal series estimation and truncated series a... In this article we study the estimation method of nonparametric regression measurement error model based on a validation data. The estimation procedures are based on orthogonal series estimation and truncated series approximation methods without specifying any structure equation and the distribution assumption. The convergence rates of the proposed estimator are derived. By example and through simulation, the method is robust against the misspecification of a measurement error model. 展开更多
关键词 ILL-POSED INVERSE Problems measurement ERRORS NONPARAMETRIC Regression ORTHOGONAL Series VALIDATION data
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Voidage Measurement of Air-Water Two-phase Flow Based on ERT Sensor and Data Mining Technology
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作者 王保良 孟振振 +2 位作者 黄志尧 冀海峰 李海青 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第2期400-405,共6页
Based on an electrical resistance tomography(ERT) sensor and the data mining technology,a new voidage measurement method is proposed for air-water two-phase flow.The data mining technology used in this work is a least... Based on an electrical resistance tomography(ERT) sensor and the data mining technology,a new voidage measurement method is proposed for air-water two-phase flow.The data mining technology used in this work is a least squares support vector machine(LS-SVM) algorithm together with the feature extraction method,and three feature extraction methods are tested:principal component analysis(PCA),partial least squares(PLS) and independent component analysis(ICA).In the practical voidage measurement process,the flow pattern is firstly identified directly from the conductance values obtained by the ERT sensor.Then,the appropriate voidage measurement model is selected according to the flow pattern identification result.Finally,the voidage is calculated.Experimental results show that the proposed method can measure the voidage effectively,and the measurement accuracy and speed are satisfactory.Compared with the conventional voidage measurement methods based on ERT,the proposed method doesn't need any image reconstruction process,so it has the advantage of good real-time performance.Due to the introduction of flow pattern identification,the influence of flow pattern on the voidage measurement is overcome.Besides,it is demonstrated that the LS-SVM method with PLS feature extraction presents the best measurement performance among the tested methods. 展开更多
关键词 two-phase flow voidage measurement electrical resistance tomography sensor data mining feature extraction
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Estimation of Nonparametric Multiple Regression Measurement Error Models with Validation Data
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作者 Zanhua Yin Fang Liu 《Open Journal of Statistics》 2015年第7期808-819,共12页
In this article, we develop estimation approaches for nonparametric multiple regression measurement error models when both independent validation data on covariables and primary data on the response variable and surro... In this article, we develop estimation approaches for nonparametric multiple regression measurement error models when both independent validation data on covariables and primary data on the response variable and surrogate covariables are available. An estimator which integrates Fourier series estimation and truncated series approximation methods is derived without any error model structure assumption between the true covariables and surrogate variables. Most importantly, our proposed methodology can be readily extended to the case that only some of covariates are measured with errors with the assistance of validation data. Under mild conditions, we derive the convergence rates of the proposed estimators. The finite-sample properties of the estimators are investigated through simulation studies. 展开更多
关键词 ILL-POSED INVERSE Problem Linear OPERATOR measurement ERRORS NONPARAMETRIC Regression VALIDATION data
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On Human Autonomic Nervous Activity Related to Weather Conditions Based on Big Data Measurement via Smartphone
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作者 Makoto Komazawa Kenichi Itao +1 位作者 Hiroyuki Kobayashi Zhiwei Luo 《Health》 CAS 2016年第9期894-904,共11页
This research uses our previously-developed smartphone camera-based heart rate change analysis system to survey the correlation between weather patterns and the autonomic nervous activity across a big data set of appr... This research uses our previously-developed smartphone camera-based heart rate change analysis system to survey the correlation between weather patterns and the autonomic nervous activity across a big data set of approximately 200,000 entries. The results showed a trend in which a significant decrease was seen in sympathetic nervous activity in both males and females—the higher the temperature. In addition, a significant increase was seen in the sympathetic nervous system in both males and females—the higher the atmospheric pressure. Lastly, a significant decrease was seen in the sympathetic nervous system in both males and females—the more precipitation there was. These results accord with prior research and with human biological phenomena, and we were able to use a data set of approximately 200,000 entries to statistically demonstrate our hypothesis. We believe this represents a valuable set of reference data for use in the health care. 展开更多
关键词 Heart Rate Variability Autonomic Nervous System Large Amount of measurement data WEATHER
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On Human Autonomic Nervous Activity Related to Behavior, Daily and Regional Changes Based on Big Data Measurement via Smartphone
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作者 Makoto Komazawa Kenichi Itao +1 位作者 Hiroyuki Kobayashi Zhiwei Luo 《Health》 CAS 2016年第9期827-845,共19页
This research uses a large amount of autonomic nervous system data (approximately 100,000 entries) to investigate the relationship between human autonomic nervous activity and behaviors, daily and regional changes. Da... This research uses a large amount of autonomic nervous system data (approximately 100,000 entries) to investigate the relationship between human autonomic nervous activity and behaviors, daily and regional changes. Data were measured via a heart rate variability analysis system that utilizes the camera of smartphones. This system was developed by the authors during previous research. The relations between autonomic nervous system and behaviors, total power and sympathetic nervous activity were found to rise after waking, while during leisure time, the total power rises and sympathetic nervous activity is inhibited. Concerning the relationship between autonomic nervous system and day of the week, it was found that total power decreases from the middle through the latter part of the week (namely, Wednesday, Thursday, and Friday), while it rises on Saturday, while the sympathetic nervous activity is suppressed on Saturday. Regarding the relationship between autonomic nervous system and region, it was found that total power is lower in the Kanto region of Japan than in others. This study also shows statistical proof (using a large amount of measurement data) to ideas held by the public for years. Thus, the data can be considered meaningful to the society, and the authors hope that it helps to improve work-life balance. 展开更多
关键词 Heart Rate Variability Autonomic Nervous System Large Amount of measurement data Activity Day of the Week Region
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Kinetic assessment of measured mass flow rates and streamwise pressure distributions in microchannel gas flows
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作者 Jing Fan Chong Xie Jianzheng Jiang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2007年第2期145-148,共4页
Measured mass flow rates and streamwise pressure distributions of gas flowing through microchannels were reported by many researchers. Assessment of these data is crucial before they are used in the examination of sli... Measured mass flow rates and streamwise pressure distributions of gas flowing through microchannels were reported by many researchers. Assessment of these data is crucial before they are used in the examination of slip models and numerical schemes, and in the design of microchannel elements in various MEMS devices. On the basis of kinetic solutions of the mass flow rates and pressure distributions in microchannel gas flows, the measured data available are properly normalized and then are compared with each other. The 69 normalized data of measured pressure distributions are in excellent agreement, and 67 of them are within 1 ± 0.05. The normalized data of mass flow-rates ranging between 0.95 and 1 agree well with each other as the inlet Knudsen number Kni 〈 0.02, but they scatter between 0.85 and 1.15 as Kni 〉 0.02 with. to some extent, a very interesting bifurcation trend. 展开更多
关键词 Microchannel . measured data .Kinetic assessment
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Block-based test data adequacy measurement criteria and test complexity metrics
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作者 陈卫东 杨建军 +1 位作者 叶澄清 潘云鹤 《Journal of Zhejiang University Science》 CSCD 2002年第1期37-41,共5页
On the basis of software testing tools we developed for programming languages, we firstly present a new control flowgraph model based on block. In view of the notion of block, we extend the traditional program\|based ... On the basis of software testing tools we developed for programming languages, we firstly present a new control flowgraph model based on block. In view of the notion of block, we extend the traditional program\|based software test data adequacy measurement criteria, and empirically analyze the subsume relation between these measurement criteria. Then, we define four test complexity metrics based on block. They are J\|complexity 0; J\|complexity 1; J\|complexity \{1+\}; J\|complexity 2. Finally, we show the Kiviat diagram that makes software quality visible. 展开更多
关键词 block NODE SEGMENT control flowgraph model test data adequacy measurement criteria test complexity metric Kiviat diagram
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Selection of extractive agent for mixture chlorobenzene and measurement of VLE data for m-dichlorobenzene-p-dichlorobenzene -o-dichlorobenzene -diphenylamine
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作者 GU Zheng-gui MA Zheng-ye LIN Jun CHEN Qi 《Journal of Chemistry and Chemical Engineering》 2008年第6期33-37,共5页
Extractive agents of extractive distillation separation for mixtures of dichlorobenzene were analyzed and compared, gas-liquid equilibrium data (VLE data) was measured for dichlorobenzene and diphenylamine, the appr... Extractive agents of extractive distillation separation for mixtures of dichlorobenzene were analyzed and compared, gas-liquid equilibrium data (VLE data) was measured for dichlorobenzene and diphenylamine, the appropriate extractive agent was selected by relatively volatility, the temperature was studied on the effect of extractive separation. VLE data was measured for dichlorobenzene, the parameters were simulated in Wilson equation. The infinite dilute activity coefficient of dichlorobenzene in diphenylamine were measured by chromatogram apparatus, the model parameters were correlated by the single parameter method for dichlorobenzene and diphenyl -amine, VLE data of m-dichlorobenzene-p- dichlorobenzene -o-dichlorobenzene-diphenylamine system was measured and calculated by six part model parameters. The results of correlation and experiment were provided a basis for study of extractive distillation simulation and experiment in this work. 展开更多
关键词 extractive agent infinite dilute activity coefficient m-dichlorobenzene P-DICHLOROBENZENE O-DICHLOROBENZENE SULFOLANE VLE data measurement and correlation
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Statistical Data Analyses on Aircraft Accidents in Japan: Occurrences, Causes and Countermeasures
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作者 Kunimitsu Iwadare Tatsuo Oyama 《American Journal of Operations Research》 2015年第3期222-245,共24页
We investigate the major characteristics of the occurrences, causes of and counter measures for aircraft accidents in Japan. We apply statistical data analysis and mathematical modeling techniques to determine the rel... We investigate the major characteristics of the occurrences, causes of and counter measures for aircraft accidents in Japan. We apply statistical data analysis and mathematical modeling techniques to determine the relations among economic growth, aviation demand, the frequency of aircraft/helicopter accidents, the major characteristics of the occurrence intervals of accidents, and the number of fatalities due to accidents. The statistical model analysis suggests that the occurrence intervals of accidents and the number of fatalities can be explained by probability distributions such as the exponential distribution and the negative binomial distribution, respectively. We show that countermeasures for preventing accidents have been developed in every aircraft model, and thus they have contributed to a significant decrease in the number of accidents in the last three decades. We find that the major cause of accidents involving large airplanes has been weather, while accidents involving small airplanes and helicopters are mainly due to the pilot error. We also discover that, with respect to accidents mainly due to pilot error, there is a significant decrease in the number of accidents due to the aging of airplanes, whereas the number of accidents due to weather has barely declined. We further determine that accidents involving small and large airplanes mostly occur during takeoff and landing, whereas those involving helicopters are most likely to happen during flight. In order to decrease the number of accidents, i) enhancing safety and security by further developing technologies for aircraft, airports and air control radars, ii) establishing and improving training methods for crew including pilots, mechanics and traffic controllers, iii) tightening public rules, and iv) strengthening efforts made by individual aviation-related companies are absolutely necessary. 展开更多
关键词 STATISTICAL data ANALYSIS AIRCRAFT Accidents CAUSES of AIRCRAFT Accidents Accident-Prevention measures Mathematical Model ANALYSIS Exponential DISTRIBUTION Negative BINOMIAL DISTRIBUTION
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Stochastic bounded consensus tracking of leader-follower multi-agent systems with measurement noises and sampled-data 被引量:1
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作者 吴治海 彭力 +1 位作者 谢林柏 闻继伟 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第12期568-575,共8页
This paper is concerned with the stochastic bounded consensus tracking problems of leader-follower multi-agent systems, where the control input of an agent can only use the information measured at the sampling instant... This paper is concerned with the stochastic bounded consensus tracking problems of leader-follower multi-agent systems, where the control input of an agent can only use the information measured at the sampling instants from its neighbours or the virtual leader with a time-varying reference state, and the measurements are corrupted by random noises. The probability limit theory and the algebra graph theory are employed to derive the necessary and sufficient conditions guaranteeing the mean square bounded consensus tracking. It is shown that the maximum allowable upper boundary of the sampling period simultaneously depends on the constant feedback gains and the network topology. Furthermore, the effects of the sampling period on the tracking performance are analysed. It turns out that from the view point of the sampling period, there is a trade-off between the tracking speed and the static tracking error. Simulations are provided to demonstrate the effectiveness of the theoretical results. 展开更多
关键词 leader-follower multi-agent systems stochastic bounded consensus tracking measurement noises SAMPLED-data
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