Curve Matching Method Research Articles

Hydraulic characterization of the Adamawa-Cameroon aquifer using inverse slope method

AbstractFifty vertical electrical soundings were carried out in the Adamawa region of Cameroon. The interpretation was done using inverse slope method (ISM) and curve matching methods. The aim was to employ the applicability and suitability of the ISM in deciphering the vertical electrical sounding (VES) data for groundwater and hydrogeophysical purposes in the Pan-African aquifers. The ISM can be used to interpret VES data collected with any electrodes array. The results obtained by the ISM geo-electrical interpretation correlate/agree well with the available lithological logs used in constraining the interpretation. The resistivity values obtained through this method are in the range of 20–900 Ω m with a mean of 241 Ω m and a standard deviation of 228 Ω m. The aquifer thickness is in the range of 2–90 m, with an average of 33 m and a standard deviation of 21 m. Resistivity, thickness and depth of the Pan-African aquifer in the Adamawa region, Central Africa have been determined and characterized using both the ISM and an integrated protocol of interpolation technique. The ISM can therefore be recommended for the interpretation of VES measurements in the similar Pan-African context worldwide.

Spatial and temporal variation of aquifer vulnerability in Miri coastal region of NW Borneo using resistivity survey and GIS

In this research, Vertical Electrical Soundings (VES) were conducted along the coastal region of Miri City, East Malaysia for two different seasons to determine the spatial and temporal variation of aquifer vulnerability through Geographic Information System (GIS). VES data was processed in IPI2Win software and curve matching method was adopted to determine the predominance curve types in the study area. The corrected data were used to create spatial maps for resistivity and thickness for each layer through ArcGIS software. Pseudo cross-sections were produced to identity the lithological variance and the movement of saline groundwater plumes. Dar Zarrouk parameters such as longitudinal conductance (S) and transverse resistance (T) were also calculated and spatial maps were prepared to differentiate freshwater and saline water aquifers in the study area. From the results, it was found that the dominant curve types identified in the study area are Q type (24%) and QH type (28%) during the Northeast monsoon (NEM); whereas QH type (19%) and QHKH type (18%) are identified during the Southwest monsoon (SWM). The significant resistivity values that indicate the saline water intrusion (SWI) are 0.49–47.6 ohm.m and 4.34–40.2 ohm.m, which was identified from the northern and southern parallel pseudo cross-sections. Overall, the study reveals that the intensive SWI occurred during SWM, compared to NEM. SWI was observed with low resistivity at a deeper depth of 20 m on the northern side of the study area. The southern urban area of Miri City is continuously prone to infiltration of brackish water at shallow depth caused by anthropogenic activities.

A recurrent curve matching classification method integrating within-object spectral variability and between-object spatial association

Object-based image analysis (OBIA), which has been commonly used for land cover and land use classification, may encounter challenges when satellite images’ spatial resolution achieves at the sub-meter level. An image object may exhibit spectral heterogeneity, causing traditional object-level statistical measures such as mean values of the pixels in an object not suited to represent the feature of the object. Additionally, an image object may have strong spatial association with its surroundings. Traditional OBIA only considers spatial features of individual object, but ignoring spatial arrangement or spatial association between objects. This paper proposes a new OBIA method by integrating within-object spectral variability and between-object spatial association. The within-object spectral variability is captured by the histograms of the pixels in an object across multispectral bands to reflect the heterogeneity of their pixel values. Based on this, the initial classification result is obtained using non-parametric curve matching methods. Then, the between-object spatial association is represented by curves derived from the frequency of pairwise classes in four main directions, also in the form of curves. The curves now composed of both the histograms of spectral feature and the class pair frequency of spatial feature are then fused for another curve matching based classification. This recurrent process is repeated and the spatial association is recaptured from the previous classification result at each iteration until a stopping criterion is satisfied. The curve matching classification method based on histograms of spectral feature is superior to traditional OBIA based on only object-level statistical measures since it fully characterizes spectral variability in the objects. The between-object spatial association works as a spatial filter that considers spatial arrangement of classes in a neighborhood. The developed method is especially suitable for classifying high spatial resolution (HSR) images with land cover/land use classes in typical urban areas.

Hydrogeophysical investigation for the aquifers in part of Ilorin, Central Nigeria: Implication on groundwater prospect

Hydrogeophysical study involving the use of Vertical Electrical Sounding (VES) was carried out in part of the basement complex rocks of Ilorin, central Nigeria, with the aim of determining its geoelectric parameters and groundwater potential. A total of thirty (30) VES were carried out using Schlumberger electrode configuration, with half electrode separation (AB/2) varying from 1m to 100m. Information on the subsurface lithologies, overburden thickness and aquiferous layers were obtained from the different VES locations in the study area. From the quantitative interpretations of the data collected, using the method of curve matching with the Orellana-Mooney master curves and 1-D forward modeling with WinResist 1.0 version software, three to five lithologic units were identified in the study. These include: the topsoil, sandy/lateritic clay/laterite, the weathered basement, the fractured basement and the fresh bedrock which are predominantly of the ‘KH’ curve type (30%), followed by ‘H’ type (26.7%), other type curves include ‘QH’ (16.7%), ‘HKH’, ‘HA’ and ‘A’ (6.7% each) and KQ and KQH (3.3% each). The weathered layer and the fractured basement constitute the main aquifer units. The aquifers are of generally low resistivity values (mostly below 100 Ω-m). The depths to dry bedrock at the chosen VES locations vary from 2.7 to 62.7 m with a mean value of 13.02 m in the study area. The geoelectrical interpretations of data obtained in these areas have permitted the delineation of the study area into low and moderate groundwater potential zones. This study is expected to assist in future planning for groundwater resources.
 Keywords: Hydrogeophysical, Basement Complex, Groundwater, Electrical Soundings, Weathered, Fractured

Integrating Resistivity Techniques for Optimum Groundwater Exploration and Development within a Hotel Facility in Osogbo, Southwestern Nigeria

This work is an attempt to combine dipole-dipole profiling and vertical electrical sounding techniques of electrical resistivity methods to investigate the groundwater potential within the premises of a 3-star hotel facility in Osogbo, Nigeria by delineating the geoelectric layers, delineating the low resistivity layers, determining the lithologies and hence, delineating the groundwater bearing zones. The five vertical electrical sounding data were collected along two pre-surveyed dipole-dipole traverses at right angle to each other beside the fences of the premises using the ABEM SAS 300c terrameter. The observed data were interpreted quantitatively using curve matching and computer-assisted iteration method using the WinResist and Dipro software. The results of the inversion show that the lithology comprises of the top soil and an intermittent sequence of sand and lateritic clay having varying resistivity and thickness. The aquiferous layer was observed to be located at a depth of 23 m to 25 m due to the low resistivity and high thickness of the aquiferous layer. The result of the 2-D imaging closely correlates with the result of the vertical electrical sounding. Thus, combining these techniques in groundwater investigation has achieved similar result as the Werner technique and has reduced ambiguity and error in positioning for drilling.
 Keywords: Resistivity, Groundwater Exploration, Dipole-Dipole

Tree Species Classification of Forest Stands Using Multisource Remote Sensing Data

The spatial distribution of forest stands is one of the fundamental properties of forests. Timely and accurately obtained stand distribution can help people better understand, manage, and utilize forests. The development of remote sensing technology has made it possible to map the distribution of tree species in a timely and accurate manner. At present, a large amount of remote sensing data have been accumulated, including high-spatial-resolution images, time-series images, light detection and ranging (LiDAR) data, etc. However, these data have not been fully utilized. To accurately identify the tree species of forest stands, various and complementary data need to be synthesized for classification. A curve matching based method called the fusion of spectral image and point data (FSP) algorithm was developed to fuse high-spatial-resolution images, time-series images, and LiDAR data for forest stand classification. In this method, the multispectral Sentinel-2 image and high-spatial-resolution aerial images were first fused. Then, the fused images were segmented to derive forest stands, which are the basic unit for classification. To extract features from forest stands, the gray histogram of each band was extracted from the aerial images. The average reflectance in each stand was calculated and stacked for the time-series images. The profile curve of forest structure was generated from the LiDAR data. Finally, the features of forest stands were compared with training samples using curve matching methods to derive the tree species. The developed method was tested in a forest farm to classify 11 tree species. The average accuracy of the FSP method for ten performances was between 0.900 and 0.913, and the maximum accuracy was 0.945. The experiments demonstrate that the FSP method is more accurate and stable than traditional machine learning classification methods.

Evaluation of groundwater potential of bedrock aquifers in Geological Sheet 223 Ilorin, Nigeria, using geo-electric sounding

Electrical resistivity data acquired in one hundred and ten (110) locations using vertical electrical sounding method of Schlumberger array have been used to study the hydrogeological properties and groundwater storage potential of bedrock aquifers in an area covered by Geological Sheet 223 Ilorin, Nigeria. The aim of the study was to identify productive aquifer zones for citing boreholes for community water supply. The data acquired were processed and interpreted using auxiliary curve matching and computer automation method to delineate the different geo-electric layers, their resistivities, thicknesses, and depths. Geo-electrical layers were interpreted to their equivalent geological layers using borehole lithological logs from the study area. Then, the hydraulic conductivity, transmissivity, fracture contrast, reflection coefficient were estimated and plotted in the form of 2D maps to describe the spatial variations of these parameters in the area. The results of the study revealed the presence of three to five geo-electric layers. The geo-electric layers, from top to the bottom, corresponds to the topsoil layer, lateritic layer, weathered rock layer, fractured rock layer, and the fresh basement rock. Lateritic and/or fractured rock layers were not delineated in some places. The weathered and fractured rock layers, where present, correspond to the aquifer units. The thickness of the fracture aquifer ranges from 0.6 to 33.6 m while the thickness of the weathered aquifer ranges from 1.4 to 49.3 m. The transmissivity, T , and hydraulic conductivity, K , range from 3 to 1200 m2/day and 1 to 48 m/day, respectively. The reflection coefficient and fracture contrast map showed the presence of water-bearing fractures and shared some similarities with T and K maps. A mathematical model for predicting groundwater potential, {text{GW}}_{text{P}} , of weathered aquifer in the basement complex terrain was proposed in this study. The consistencies between the overall groundwater potential map and aquifers parameters distributions maps suggest the appropriateness of the proposed mathematical model for predicting groundwater potential of weathered rock in the basement complex area of Nigeria. The western, northwestern, and central parts of the study area, having {text{GW}}_{text{P}} greater than 0.6 (60%), were recommended for groundwater development through boreholes drilled to a depth ranging between 75 and 100 m.

Hydrogeophysical Investigation of Groundwater Systems in Otukpo, Benue State, North-Central Nigeria

Hydrogeophysical investigation of groundwater systems in Otukpo, Benue State, Nigeria has been carried out using vertical electrical sounding (VES) technique to delineate the groundwater potentials across the study area. Ten (10) vertical electrical soundings were carried out during the geophysical survey using the Schlumberger configuration of electrical resistivity method with maximum current and potential electrode spacing of 600 meters and 80 meters respectively. The VES data was qualitatively and quantitatively interpreted using the conventional curve matching and computer iteration methods. The result of qualitative interpretation depicts that the VES curves obtained within the study area are mainly the QH and KQH which are typically indicative of a sedimentary terrain. The results of the quantitative interpretation reveal that the resistivity values from shallow subsurface to the depth of about 500 m of the VES stations ranges from 3 Ωm to 1250 Ωm. The VES results also show that the study is characterized by seven (7) different inferred lithological layers namely; topsoil, sand/silt, laterite, clay, shale, sandstone and the basement rock. The result also reveals that the depth to water-saturated unit ranges from 450 to 500 meters within the study area. Two distinguished aquifer types were obtained within the area namely; unconfined and confined aquifers. The findings reveal that the future borehole drillers should target the confined aquifers situated between the depths of 450meters to 500 meters beneath the surface for sustainable groundwater yield across the study area.

Geo-resistivity data set for groundwater aquifer exploration in the basement complex terrain of Nigeria, West Africa.

To delineate prolific groundwater aquifers in the basement complex terrain of Ilorin, Nigeria, West Africa, a carefully designed Electrical Resistivity Surveys were undertaken at eighty-five (85) stations using Vertical Electrical Sounding (VES) technique with Schlumberger array. Data acquisition system comprised SAS 3000 ABEM Resistivity Meter, a D. C. battery, four metallic electrodes, electrical cables, portable Geographic Positioning System (GPS), hammers, measuring tapes, and other accessories. In addition to the resistivity data, the geographic coordinates of the survey points were measured for ease of geo-referencing of the exact points where the data were collected and for secondary use of the data. The data acquired were processed, analysed and interpreted using auxiliary curve matching techniques and computer iteration method. The results were used to: evaluate the subsurface in terms of the different geo-electric layers, their thicknesses, depths, and resistivities; evaluate the groundwater potential of the aquifer; identify suitable sites for locating boreholes for groundwater exploitation; and recommend depths to borehole bottom in the different parts of the study area. The data presented can be reused to determine the protective capacity of the overburden material against groundwater contamination; to determine the engineering-geophysics and geotechnical properties of the rocks for Civil Engineering applications; for predicting groundwater flow models; and for mineral exploration within the area. The data presented can be used with other geophysical and geological data acquired from the same area for a better evaluation of the subsurface for multipurpose applications.

Geophysical investigation of foundation failure at Medina Estate, Lagos, Southwestern Nigeria

Integrated geophysical investigation involving Ground Penetrating Radar (GPR) and Electrical Resistivity methods were carried out at Medina Estate, Lagos southwestern Nigeria to map the subsurface lithology in order to delineate its peat stratigraphy that has been causing foundation failure in the area. Twenty-one traverses (varying from 35-880 m in length) of Ground Penetrating Radar (GPR) survey were conducted along the streets of Medina trending NE-SW and NW-SE directions using the Mala 250 MHZ bi-static shielded antenna. Thirty-six Vertical Electrical Soundings (VES) were carried out using Schlumberger electrode array at some selected points along the established traverses within the area. The GPR data were processed into radar section using Rad Explorer software. The VES data were interpreted quantitatively using the partial curve matching method and 1-D forward modeling with Win Resist Software. Available litho-logs from boreholes drilled within the area were compared with the geophysical results. Results of the GPR survey delineated three geologic layers which include the topsoil with high amplitude, parallel to sub parallel, horizontal reflections, with thickness varying from 1 to 2 m across the entire profiles and composed of lateritic clay; peat layer with low amplitude, parallel sinuous/wavy reflections with depth of occurrence ranging from 2.0 to 8 m and clay with low amplitude, planar, horizontal, sub-parallel reflections underlying the peat layer. Vertical Electrical Sounding results revealed the presence of three geological layers which are the topsoil, peat and clay and sandy clay with layer resistivity values ranging from 20- 225 Ωm, 5 – 90 Ωm and 36 to 366 Ωm and thickness values ranging from 0.5 – 2 m, 4.0-29.0 m and infinity respectively. Borehole information confirms the occurrence of shallow peat with depth ranging from 1.5 to 9 m and clay layer with depth ranging from 9 to 21 m beneath the area. The GPR survey results correlates with the well logs acquired in the study area. Based on the correlation of the geophysical results with the well logs, the GPR gives better information about the peat layer compared to the Electrical ResistivityMethod. The information obtained from this study shows that the soils at shallow depth are organic soils which are difficult foundation materials because they exhibit very high compressibility, as such making shallow foundation impossible except some form of soil improvement is carried out. The alternative approach is the adoption of deep foundations in form of piles.
 Keywords: Foundation Failure, Geophysical Investigation, Ground Penetrating Radar, Vertical Electrical Sounding, Peat.

An improved similarity-based prognostic algorithm for RUL estimation using an RNN autoencoder scheme

Remaining useful life (RUL) estimation of a degrading system is the major prognostic activity in many industry applications. This paper presents an improved version of the similarity-based curve matching method for the remaining useful life estimation of a mechanical system, which is a companion paper of our previous work on RUL estimations using a bidirectional recurrent neural network (RNN) based autoencoder scheme. We propose a zero-centering rule to tackle the varying initial health across instances (systems) when using the similarity-based health index curve matching technique to identify the training instances that share a similar degradation pattern with the test instance whose RUL needs to be determined. However, this rule will also induce a significant prediction error, especially when the off-line training instances are abundant, or the true RULs of the on-line test instances are large. Thus, an ensemble approach that integrates the RUL estimations obtained from the similarity-based curve matching techniques, with and without the zero-centering rules, is introduced to increase the robustness and accuracy of proposed method for RUL estimations. We evaluate the prognostic performance of the ensemble algorithm and standalone algorithms on four publicly available turbofan engine degradation datasets. The results demonstrate that the proposed ensemble approach gives more robust and reliable RUL estimations compared to any independent algorithm used on all the studied datasets.

Mapping sub-volcanic geology using magnetic data

SummaryVolcanic layers within sedimentary basins cause significant problems for petroleum exploration because the attenuation of the seismic signal masks the underlying geology.A test study was conducted for the South Australia Government to map the thickness of volcanics and sub-volcanic geology over a large area in the Gawler Range Volcanics (GRV) province. The area is covered by good quality magnetic data. The thickness of volcanics and basement configuration was unknown as there has only been a limited amount of drilling.The Automatic Curve Matching (ACM) method was applied to located magnetic data and detected magnetic sources within different rock units, providing their depth, location, geometry and magnetic susceptibility. The magnetic susceptibilities detected by ACM allowed the differentiation of the volcanics and the underlying basement. The base of volcanics and the depth to the top of basement was mapped along 75km North-South profiles, that were spaced 1km apart over a distance of 220km. The volcanic and basement magnetic susceptibilities and the magnetic source distribution pattern, were used as key determinants to interpret the depth to the two interfaces. After the results for each interface were gridded, the surfaces were used to produce a 3D voxel model of the volcanics. A magnetic field was generated from the model and subtracted from the RTP data to produce the field generated by the sub-volcanic geology.

A Mobile Anchor Node Assisted RSSI Localization Scheme in Underwater Wireless Sensor Networks.

In this paper, a mobile anchor node assisted RSSI localization scheme in underwater wireless sensor networks (UWSNs) is proposed, which aims to improve location accuracy and shorten location time. First, to improve location accuracy, we design a support vector regression (SVR) based interpolation method to estimate the projection of sensor nodes on the linear trajectory of the mobile anchor node. The proposed method increases the accuracy of the nonlinear regression model of noisy measured data and synchronously decreases the estimation error caused by the discreteness of measured data. Second, to shorten location time, we develop a curve matching method to obtain the perpendicular distance from sensor nodes to the linear trajectory of the mobile anchor node. The location of the sensor node can be calculated based on the projection and the perpendicular distance. Compared with existing schemes that require the anchor node to travel at least two trajectories, the proposed scheme only needs one-time trajectory to locate sensor nodes, and the location time is shortened with the reduction in the number of trajectories. Finally, simulation results prove that the proposed scheme can obtain more accurate sensor node location in less time compared with the existing schemes.

Extraction of Earthquake-Induced Collapsed Buildings From Bi-Temporal VHR Images Using Object-Level Homogeneity Index and Histogram

The availability of very high resolution (VHR) satellite images has made the analysis of remotely sensed data an increasingly effective tool for the extraction of urban building damage caused by earthquakes. In this study, we proposed a novel method to extract collapsed buildings from bi-temporal VHR images using object-level homogeneity index (OHI) and object histogram. The OHI, which is calculated using an improved spatial homogeneity index of pixel, quantifies internal homogeneity of image object generated from image segmentation. The object histogram quantifies the spectral variability of image object. Ground objects that are intact and significantly different from collapsed buildings, such as vegetation and non-vegetated homogeneous areas, were first extracted from post-event VHR image using OHI and normalized difference vegetation index and were masked out. Collapsed buildings were then extracted from bi-temporal images of the remaining areas using object histogram and a curve matching method, multi-reference spectral angle mapper. The proposed method was evaluated and compared to two existing methods using bi-temporal QuickBird images over Bam, Iran, which was heavily hit by an earthquake in 2003. The experimental results showed that the proposed method outperformed the two comparative methods, with the increase of 11.38 and 5.65% in overall accuracy, and 14.27 and 7.83% in F-score, respectively. The proposed method provides a fast and reliable method for extraction of collapsed buildings.

MAPPING OF SALTWATER INTRUSION AT IGBOKODA, SOUTHWESTERN, NIGERIA USING COMBINED GEOPHYSICAL AND CHEMICAL TECHNIQUES

<p>This research work was set out to map saltwater intrusion in Igbokoda area of Ilaje, Ondo State, Southwestern, Nigeria using combined geophysical and chemical techniques. Eight (8) Vertical Electrical sounding were carried out using the Schlumberger Electrode array system with maximum spread of (AB/2) 133 m and water samples were acquired and analysed using atomic absorption spectrometer. The VES data was interpreted by the method of partial curve matching and computer iteration technique using Winresist software. The result obtained revealed four geoelectric layers. The saltwater intrusion originated from movement of seawater into the freshwater aquifer coupled with human activities.</p>

Hydrogeology Tests Performed in Shazaoyuan Candidate Site for China’s HLW Geodisposal

Rock mass hydraulic conductivity is one of the most important indexes for candidate site quantitative assessment of high-level radioactive waste disposal. 178 hydrogeology tests, mainly constant head injection test and pulse test, were performed in the 4 boreholes drilled in Shazaoyuan candidate site. Reliable hydraulic conductivity was obtained with transient curve matching methods. The result shows that the hydraulic conductivity was high heterogeneous; the maximum hydraulic conductivity was 9.30×10-8m/s and 93% of the sections were lower than 10-8m/s. Shazaoyuan candidate site can be inferred as one of the most potential sites for the geological disposal of China’s HLW in the view of low permeability.

MICOP: Maximal information coefficient-based oscillation prediction to detect biological rhythms in proteomics data

BackgroundCircadian rhythms comprise oscillating molecular interactions, the disruption of the homeostasis of which would cause various disorders. To understand this phenomenon systematically, an accurate technique to identify oscillating molecules among omics datasets must be developed; however, this is still impeded by many difficulties, such as experimental noise and attenuated amplitude.ResultsTo address these issues, we developed a new algorithm named Maximal Information Coefficient-based Oscillation Prediction (MICOP), a sine curve-matching method. The performance of MICOP in labeling oscillation or non-oscillation was compared with four reported methods using Mathews correlation coefficient (MCC) values. The numerical experiments were performed with time-series data with (1) mimicking of molecular oscillation decay, (2) high noise and low sampling frequency and (3) one-cycle data. The first experiment revealed that MICOP could accurately identify the rhythmicity of decaying molecular oscillation (MCC > 0.7). The second experiment revealed that MICOP was robust against high-level noise (MCC > 0.8) even upon the use of low-sampling-frequency data. The third experiment revealed that MICOP could accurately identify the rhythmicity of noisy one-cycle data (MCC > 0.8). As an application, we utilized MICOP to analyze time-series proteome data of mouse liver. MICOP identified that novel oscillating candidates numbered 14 and 30 for C57BL/6 and C57BL/6 J, respectively.ConclusionsIn this paper, we presented MICOP, which is an MIC-based algorithm, for predicting periodic patterns in large-scale time-resolved protein expression profiles. The performance test using artificially generated simulation data revealed that the performance of MICOP for decaying data was superior to that of the existing widely used methods. It can reveal novel findings from time-series data and may contribute to biologically significant results. This study suggests that MICOP is an ideal approach for detecting and characterizing oscillations in time-resolved omics data sets.

MAPPING OF SALTWATER INTRUSION AT IGBOKODA, SOUTHWESTERN, NIGERIA USING COMBINED GEOPHYSICAL AND CHEMICAL TECHNIQUES

This research work was set out to map saltwater intrusion in Igbokoda area of Ilaje, Ondo State, Southwestern, Nigeria using combined geophysical and chemical techniques. Eight (8) Vertical Electrical sounding were carried out using the Schlumberger Electrode array system with maximum spread of (AB/2) 133 m and water samples were acquired and analysed using atomic absorption spectrometer. The VES data was interpreted by the method of partial curve matching and computer iteration technique using Winresist software. The result obtained revealed four geoelectric layers. The saltwater intrusion originated from movement of seawater into the freshwater aquifer coupled with human activities.

Multi-objective sequence optimization of PCB component assembly with GA based on the discrete Fréchet distance

A new mechanism，namely a combination of curve matching method based on the discrete Fréchet distance and evolutionary algorithms，is proposed to solve pick-and-place sequence optimisation problems as a multi-objective optimisation problem. The essence of the mechanism is to accomplish the comparison of objective vectors with curve matching method. The objective vector is mapped into the array of points with a binary mapping operator and the discrete Fréchet distance is utilised to measure the similarity between the reference array of points and the comparison array of points. The genetic algorithm based on the discrete Fréchet distance (FGA) is proposed. To test the new mechanism, together with FGA, three other test algorithms are selected to solve the sequence optimisation problem. The simulation results indicate that FGA outperforms other algorithms. This new mechanism is rational and feasible for multi-objective pick-and-place sequence optimisation problems.

A novel clustering algorithm of extracting road network from low-frequency floating car data

Keeping the digital road maps up-to-date is of critical importance, because the quality of many road-dependent services relies on it, but traditional measurement methods are still time-consuming and expensive. With the GPS technology and wireless communication technology maturing, the positioning data from floating car become a new data source for updating road maps. The paper presents a novel incremental clustering algorithm for automatically extracting the topology of the road network employing the floating car data. A trajectory is selected as a road Link and then the remaining trajectories are added in turn until all tracks are processed. Further, the algorithm determines whether to merge the trajectory or divide it into a new Link by judging the relations of the space position between the newly added trajectory and the existing Link. A partial curve matching method based on Frechet distance is employed to measure the partial similarity between a Trajectory and a Link and the time complexity of the proposed algorithm is reduced. Experiments show that the algorithm can quickly extract the geometric shape and topology of the road network with lightweight floating car data.