Real Size Research Articles

A Bit Torrent Traffic Optimization Method for Enhancing the Stability of Network Traffic

With the extensive use of peer-to-peer applications in recent years, the network traffic becomes more dynamic and less predictable, which leads to the decline of network resource utilization and the degradation of network performance. Aiming towards the above problems, we explore how to strengthen the cooperation between peer-to-peer applications and networks, making the application adjust its own traffic mode according to current network traffic status to enhance the stability of network traffic. We improve two key algorithms of peer selection and choking/unchoking in the protocol and introduce traffic relaxation to characterize traffic state while taking the current most popular peer-to-peer application (bit torrent protocol) as an example. In our improved method, peers are selected probabilistically according their traffic relaxation, and the double-parameter selection problem that simultaneously considers the traffic relaxation and transfer rate of peers is also solved. Finally, we conduct simulation experiments in two real network typologies with real traffic matrix data and different sizes of bit torrent swarms; the experimental results show that our method can significantly improve the stability of the network traffic without sacrificing or even improving the performance of the bit torrent protocol when compared with original BT protocol.

Decadal changes in adult size of salmon-eating killer whales in the eastern North Pacific

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 40:183-188 (2019) - DOI: https://doi.org/10.3354/esr00993 ESR Special: Drones in conservation research NOTE Decadal changes in adult size of salmon-eating killer whales in the eastern North Pacific Molly J. Groskreutz1,2, John W. Durban1,*, Holly Fearnbach2, Lance G. Barrett-Lennard3, Jared R. Towers4, John K. B. Ford4 1Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 8901 La Jolla Shores Drive, La Jolla, CA 92037, USA 2SR3, SeaLife Response, Rehabilitation and Research, 2255 Harbor Avenue SW, Suite 101, Seattle, WA 98126, USA 3Coastal Ocean Research Institute, PO Box 3232, Vancouver, BC V6B 3X8, Canada 4Fisheries and Oceans Canada, Pacific Biological Station, Cetacean Research Program, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada *Corresponding author: john.durban@noaa.gov ABSTRACT: Two populations of killer whales aggregate around Vancouver Island to feed primarily on Chinook salmon. Aerial photogrammetry of endangered southern residents has documented some adults growing to smaller lengths in recent decades, suggesting that early growth may have been constrained by low Chinook availability in the 1990s. We investigated whether growth and adult length were also constrained in the more abundant northern residents. Photographs were collected from an unmanned hexacopter at altitudes of 30 to 37 m over 4 yr, 2014 to 2017. Images were linked to 78 individuals of known age and sex based on distinctive saddle patch pigmentation. The length of each whale was estimated by measuring pixel dimensions between both the snout and dorsal fin and the dorsal fin and fluke; these were scaled to real size using camera lens focal length and altitude, determined by a laser or pressure altimeter. Total length, derived by summing the longest (flattest) of each measure, ranged from 2.42 m for a first-year calf to 7.45 m for the largest adult male. A Bayesian change point analysis revealed that adult whales <40 yr old were on average shorter by 0.44 m than older adults, which grew to typical lengths of 6.28 and 7.14 m for females and males, respectively. This mirrors the growth trends reported for southern residents, supporting demographic evidence of correlated prey limitation in both populations. The growth data suggest that the effects of nutritional stress are not only acutely lethal but also have long-term consequences for the condition of whales in both populations. KEY WORDS: Photogrammetry · Drone · UAS · UAV · Growth · Nutrition · Orca Full text in pdf format PreviousNextCite this article as: Groskreutz MJ, Durban JW, Fearnbach H, Barrett-Lennard LG, Towers JR, Ford JKB (2019) Decadal changes in adult size of salmon-eating killer whales in the eastern North Pacific. Endang Species Res 40:183-188. https://doi.org/10.3354/esr00993 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 40. Online publication date: November 14, 2019 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2019 Inter-Research.

Wake of a Ducted Vertical Axis Tidal Turbine in Turbulent Flows, LBM Actuator-Line Approach

Vertical axis tidal turbines are devices that extract the kinetic energy from tidal currents. Tidal currents can be highly turbulent. Since ambient turbulence affects the turbine hydrodynamic, it is critical to understand its influence in order to optimize tidal farms. Actuator Line Model (ALM) combined with Large Eddy Simulation (LES) is a promising way to comprehend this phenomenon. In this article, an ALM was implemented into a Lattice Boltzmann Method (LBM) LES solver. This implementation gives good results for predicting the wake of a vertical axis tidal turbine placed into a turbulent boundary layer. The validated numerical configuration was then used to compute the wake of a real size ducted vertical axis tidal turbine. Several upstream turbulence rates were simulated. It was found that the shape of the wake is strongly influenced by the ambient turbulence. The cost-to-precision ratio of ALM-LBM-LES compared to fully resolved LBM-LES makes it a promising way of modeling tidal farms.

Influence of network properties on a migration induced secular height trend by Monte Carlo simulation.

Background: Recent research reported height biased migration of taller individuals and a Monte Carlo simulation showed that such preferential migration of taller individuals into network hubs can induce a secular trend of height. In the simulation model taller agents in the hubs raise the overall height of all individuals in the network by a community effect. However, it could be seen that the actual network structure influences the strength of this effect. In this paper the background and the influence of the network structure on the strength of the secular trend by migration is investigated. Material and methods: Three principal network types are analyzed: networks derived from street connections in Switzerland, more regular fishing net like networks and randomly generated ones. Our networks have between 10 and 152 nodes and between 20 and 307 edges connecting the nodes. Depending on the network size between 5.000 and 90.000 agents with an average height of 170cm (SD 6.5cm) are initially released into the network. In each iteration new agents are regenerated based on the actual average body height of the previous iteration and, to a certain proportion, corrected by body heights in the neighboring nodes. After generating new agents, a certain number of them migrated into neighbor nodes, the model let preferentially taller agents migrate into network hubs. Migration is balanced by back migration of the same number of agents from nodes with high centrality measures to less connected nodes. The latter is random as well, but not biased by the agents height. Furthermore the distribution of agents per node and their correlation to the centrality of the nodes is varied in a systematic manner. After 100 iterations, the secular trend, i.e. the gain in body height for the different networks, is investigated in relation to the network properties. Results: We observe an increase of average agent body height after 100 iterations if height biased migration is enabled. The increase rate depends on the height of the neighboring factor, the population distribution, the relationship between population in the nodes and their centrality as well as on the network topology. Networks with uniform like distributions of the agents in the nodes, uncorrelated associations between node centrality and agent number per node, as well as very heterogeneous networks with very different node centralities lead to biggest gains in average body height. Conclusion: Our simulations show, that height biased migration into network hubs can possibly contribute to the secular trend of height increase in the human population. The strength of this "tall by migration" event depends on the actual properties of the underlying network. There is a possible significance of this mechanism for social networks, when hubs are represented by individuals and edges as their personal relationships. However, the required high number of iterations to achieve significant effects in more natural network structures in our models requires further studies to test the relevance and real effect sizes in real world scenarios.

Velocity distribution in open channel flow with spatially distributed roughness

A numerical procedure is proposed to estimate the velocity distribution in open channel flow, for engineering applications. A method based on the mixing length model and sub-division of the wetted surface, is modified to easily integrate a lateral distribution of roughness. Several friction models for vegetated or rough flows can be added, two of which have been tested. The numerical procedure was developed with a commercial software (Matlab) to ensure fast computation and possible coupling with 1D hydraulic models. The validation of the computation has been done with rectangular and compound channels with spatially distributed roughness. The usefulness of the method for ecohydraulics is demonstrated with two applications: box culvert design for fish passes and 1D modelling of mountain river flows for which experimental results from a laboratory scale-model is compared to predictions. The interest of a friction law calibrated with a real grain roughness size is put forward.

Prevalence and Associated Factors of Violence against Hospital Staff at Amanuel Mental Specialized Hospital in Addis Ababa, Ethiopia.

Background. Violence at the workplace has become an alarming phenomenon worldwide. The real size of the problem is largely unknown and recent information shows that the current knowledge is only the tip of the iceberg. The enormous cost of violence at the workplace for person and community at large is becoming more apparent. It could be physical, sexual, and verbal in nature and could be actual or threatened. Objectives. To access prevalence and associated factors of violence against hospital staff at Amanuel Mental Specialized Hospital Addis Ababa, Ethiopia. Methods. An institution based cross-sectional study was employed in 2017. The data were collected using Workplace Violence in the Health Sector Country Case Study Questionnaire from 496 participants. Participants had been selected using simple random sampling technique and data were collected using a self-administered structured questionnaire. The collected data were entered into Epi-data version 3.1, and SPSS version 21 was used for Analysis. Binary logistic regression was fitted to identify factors associated with the outcome variable. Result. From 496 staff intended to have participated in this study, complete data were obtained from 435, making a response rate of 87.7%. This research showed high prevalence of violence and we have got that staff had been exposed to physical violence 36.8%, verbal violence 62.1%, and sexual violence 21.8 % over the past year, respectively. Age, sex, and contact with the patient were statistically significant variables (p < 0.05). Conclusion and Recommendation. According to this study, majority of AMSH staff were violated by the patient they care.

Augmented Reality for Forming Technology – Visualisation of Simulation Results and Component Measurement

In sheet and bulk forming, numerical simulation has become established over the last 20 years as an indispensable tool for research and industrial practice. The numerical calculation of forming processes supports a time- and cost-efficient development in the context of a virtual product evaluation. Currently, simulation and measurement results are mainly displayed on conventional screens. However, this approach has several disadvantages. On the one hand, only cut-outs can be displayed, especially in the case of large components. A visualisation of entire components in real size is often not possible. On the other hand, no direct comparison with the real components is possible. Augmented Reality is a promising approach to solve the challenges outlined above. As part of the contribution, an innovative approach for component validation based on Augmented Reality technology will be introduced. Thereby, the visualisation using different Augmented Reality devices and the feasibility of a measurement task with Augmented Reality devices will be presented.

Magnetic Simulator Testbed for APSCO Student Small Satellite Project

The Student Small Satellite (SSS) is a university project of Asia-Pacific Space Cooperation Organization (APSCO), composed by one microsatellite (SSS-1) and two 3U CubeSats (SSS-2A and SSS-2B). Regarding SSS-1 and SSS-2A satellites, the active 3-axis magnetic control strategy has been applied in the Attitude Determination and Control System (ADCS). In this paper, the necessary study for the development of a Magnetic Simulator Testbed for the SSS-1 and SSS-2A satellites was performed using one pairs of Helmholtz coils for each axis of rotation (X, Y, Z). Each pair of coil can generate a sufficiently large and stable magnetic field that simulate the Earth’s magnetic field but with a reliable level of accuracy, to perform the ADCS test on the satellites. Matlab software was used to generate the propagation of the orbit for the satellites, to calculate the Earth’s magnetic field around that orbit and simulate a pair of Helmholtz coil in each axis of rotation to reproduce the Earth’s magnetic field using the Biot-Savart Law. The results obtained for propagation of the orbit, calculation of terrestrial magnetic field and reproduction of the magnetic field through the Magnetic Simulator Testbed, were very close to the results obtained in important researches previously consulted, giving reliability to this research and allowing an analysis to determine the real physical size that Magnetic Testbed should have. The size determined, is very close to what was expected, allowing to conclude the reliability and viability of the development of the Magnetic Testbed for APSCO SSS Project.

Numerical simulation of a draining vessel

In this paper the models of a theoretical tank and a real size draining vessel are described and numerically simulated. The main idea is to demonstrate the Toricelli’s law theorem for fluid dynamics for ideal liquid both for a theoretical vertical cylindrical tank and for a different geometry horizontal vessel of the same volume as the tank and compare the total time of liquid leaving the space of both of the reservoirs. The simulation is a multiphase problem containing two phases, which are water and air, is based on the VOF (volume of fluid) method discrete elements method (DEM) for simulating the sand bed formation for outlet nozzle capacity evaluation. As a result there are two-phase (gas-liquid) models of an “ideal” tank and an industrial vessel numerically calculated for determining and comparing the total time of water draining, and an extra model showing the dependence of sediment layer thickness on the outlet nozzle capacity.

Study of the Special Features of the Surface of Application Hemostatic Implants

Background: One of the important unsolved problems of hepatobiliary surgery is to stop the bleeding of the parenchymal organ. The most promising means of local hemostasis are spongy implants made of various materials, the study of which is one of the leading directions in modern surgery. Nevertheless, despite the relevance of the research, there is no uniform classification of the structural features of such hemostatics. Aims: to study the features of the surface of the application of hemostatic implants based on collagen and Carboxymethylcellulose Sodium. Materials and methods: the authors performed light microscopy of the samples, photographing and subsequent processing of the photographs obtained using the trial version of the graphic editor Adobe Photoshop CS6 (Adobe Systems, San Jose, United States of America) to obtain black and white images by enhancing the contrast (+400 ), which excluded the possibility of false color definition. The black and white pixels were counted using the Altami Studio 3.4 program (Altami LLC, St. Petersburg, Russian Federation). Then, the real pixel size was converted into percentages using the trial version of Statistica 10.0 (Dell Software Company, Round Rock, United States of America). After that, the ratio of low areas of the implant (black pixels) to high (white pixels) was determined.&#x0D; Results: According to the data obtained, a classification was developed for the heterogeneity of the surface of the relief of hemostatic implants, according to which all of them can be divided into three groups: with weak, moderate and strong severity of the heterogeneity of the surface relief. Conclusions: when correlating the obtained results and selected groups, it was found out that the hemostatic sponge Tachocomb (Takeda Pharmaceuticals LLC, Linz, Austria) has a slightly pronounced heterogeneity of the surface relief, and the hemostatic collagen sponge (OJSC Luga Belkozin, Luga, Russian Federation) and a Carboxymethylcellulose based hemostatic sponge (developed in cooperation with Linteks LLC, St. Petersburg, Russian Federation) - moderately pronounced surface heterogeneity.

Reentrant hybrid flow shop scheduling problem with non-anticipatory sequence-dependent setup time

This paper studies a hybrid flow shop scheduling problem originated from a steam turbine rotor production. Reentrance and non-anticipatory sequence-dependent setup time are considered. The objectives are to minimise makespan and total tardiness. A mixed integer linear programming model is formulated. A bi-objective simulated annealing algorithm is developed to solve problems with real size. A modified version of the Nawaz-Enscore-Ham algorithm is applied to find a good initial solution and a Pareto search mechanism is introduced to find the Pareto set. The proposed bi-objective simulated annealing algorithm is compared with a single-objective algorithm. Experimental results demonstrate the superiority of the bi-objective algorithm. Sensitivity analysis provides valuable managerial insights for real production.

The effect of geographic range and climate on extinction risk in the deep-time amphibian fossil record

Geographic range is of crucial importance concerning the extinction risk of species. However, our understanding of how the influence of this trait on extinction risk has varied through Earth history and across different climate regimes is still rather unexplored. This is especially true for taxa that are currently of strong interest in conservation biology, displaying a strong mismatch between paleontological studies and modern efforts to quantify the extinction risk of threatened species. We herein calculated a continuous measure for the connection of geographic range and extinction risk in the deep-time amphibian fossil record. Furthermore, we evaluated the impact of climate on this connection, using two climate proxies derived from oxygen isotope data (global relative temperature change and variations in the latitudinal temperature gradient). We show that geographic ranges tended to be larger during times of comparatively small latitudinal temperature gradients. Moreover, the strength of geographic range influencing extinction risk fluctuated temporally, but remained positive at all times. The variation in range size impact on extinction risk showed a strong connection with the latitudinal temperature gradient. Our findings indicate that geographic range persists as a factor influencing species’ extinction risk through all times. However, geographic range seemed less important during times of higher environmental variability. Reasons might be the restriction of species ranges due to environmental constraints, causing ranges to become more similar and therefore lose relative importance in buffering for extinction risk, while other factors gain in importance. Simultaneously, similar ranges might be more prone to alteration by e.g. conservation biases (related to sedimentary deposition and fossilization) in relation to their real range size, resulting in a smaller signal-to-noise ratio, potentially affecting the correlation strength. We show that trait-extinction risk dynamics can vary in their intensity, and that specifically the observed impact of geographic range on extinction risk can vary with climatic changes.

Surface roughness and processing time of a medium density fiberboard cabinet door processed via CNC router, and the energy consumption of the CNC router

In recent years, medium density fiberboard has been extensively used for furniture production. Often it is painted or coated using a PVC film in modern production, after the surfaces are formed via CNC machining. The surface roughness of medium density fiberboard used in this way is very important for the quality of the surface. In previous studies, the effects of the cutting parameters of a CNC router on the surface roughness of medium density fiberboard were investigated using laboratory test samples. The present study focused on the effects of certain cutting parameters of a CNC router on the surface roughness of real size test samples. In addition, the energy consumption and total processing time of the CNC router were investigated, in relation to the cutting parameters. Three different spindle speeds (8000 rpm, 12,000 rpm, and 16,000 rpm) and feed rates (3 m/min, 5 m/min, and 7 m/min) were used. According to the data obtained, it was determined that as the spindle speed increased, the surface roughness decreased, and the total energy consumption increased. However, as the feed rate increased, the surface roughness increased, and the total energy consumption decreased.

Influence of particle size on vertical plate penetration into dense cohesionless granular materials (large-scale DEM simulation using real particle size)

The influence of the particle size on the vertical plate penetration into dense cohesionless granular materials was numerically investigated. Simulations were performed in quasi-two-dimensional conditions by changing the mean particle diameters d50 but maintaining the plate thickness B from B/d50 = 63–2.6. The initial bulk packing fraction was kept high, irrespective of the particle size. In the smallest particle size case (B/d50 = 63), the size ratio reached almost the same level as that in the laboratory experiments using natural sand particles. The results demonstrated that the mean penetration resistance force acting on the plate tip surface increases with a decrease of B/d50, while the tangential force acting on the side surfaces does not change with B/d50. Tip resistances increase linearly with the penetration depth, while the tangential resistances increase with the square of the depth regardless of B/d50. The behavior of the resistance fluctuations changes qualitatively between B/d50 = 31 and 21. For all cases, we confirmed the formation of a wedge-shaped flow with a high forward velocity in front of the plate tip. The wedge flow width was larger than the plate thickness by almost a mean particle diameter, and was responsible for the increase in the mean resistance depending on the particle size. For the large B/d50 cases only, the resistance exhibited quasi-periodic fluctuations, which was attributable to the intermittent nucleation and disappearance of the shear bands. Moreover, we investigated the dependence of B/d50 on the band evolutions by analyzing the band thickness.Graphic abstractThe influence of the particle size on the vertical plate penetration into dense cohesionless granular materials was numerically investigated using DEM. Simulations were performed in quasi-two-dimensional conditions by changing the median particle diameters d50 but maintaining the plate thickness B. The initial bulk packing fraction was kept high, irrespective of the particle size. Upper and lower figures show the result of small (B/d50 = 63) and large particle size case (B/d50 = 21), respectively. In the small particle size case (B/d50 = 63), the size ratio reached almost the same level as that in the laboratory and the dynamics of 35.5 million particles was considered. Right and left figures illustrate instantaneous shear strain rate and local packing fraction distributions, respectively. Large qualitative change in the granular behaviors as well as penetration resistance was observed between B/d50 = 31 and 21. The intermittent nucleation and disappearance of the shear bands were clearly observed only for large B/d50 cases.

Microstructure evolution of leached cement paste: Simulation and experiments

In this paper, a reactive transport model is developed to simulate changes in the microstructure of leached cementitious composites. The model simultaneously takes into account the relation between the real microscopic pore size and macroscopic porosity via MIP and nitrogen adsorption, and the coupling between pore size and the transport properties. Quantitative validation of the model is achieved by comparison of simulation and leaching experiments, and the results show good agreement in terms of both the microscopic pore size distribution and the macroscopic porosity. In addition, SEM analysis and simulations indicates that decalcification may leads to a connection of the adjacent pores, and the increase in the critical pore size is much smaller than the threshold pore size. Some adjacent pores may be connected due to the growing threshold pore size, and the new connected pores will accelerate the growth of the threshold pore size. Besides, leaching induces additional peak on differential pore size distribution curve.

A step forward towards the structural characterization of Na2Ti2O5·H2O nanotubes and their correlation with optical and electric transport properties

In this work we present the synthesis, structural, morphological, optical and electrochemical characterization of sodium titanate nanotubes (NaNT) obtained by hydrothermal means. According to our detailed structural study, we found that a Na2Ti2O5·H2O layered crystalline phase with [TiO5] pyramidal square base coordination, utilized as a building block of the nanotubes, explains satisfactorily the experimental results. This is a very important aspect, since the bibliography does not always provide structural information about titanate nanotubes. With respect to the formation mechanism we highlight the crucial role of the post treatment washing in the final crystalline structure of the nanotubes. Simulated X-rays powder diffraction patterns (XRPD), based on real size nanotubes models, were refined with experimental data. Building blocks for the NaNT model were inferred from computational simulations, by means of Density Functional Theory. The obtained tube's model characteristic dimensions were also consistent with SAXS and TEM analysis. In addition, our SAXS analysis suggested that the presence of humidity in the cavities of titanate nanotubes is progressively lost at the 80–100 °C temperature range, in good agreement with thermogravimetric analysis. Electrochemical impedance spectroscopy analysis for dried samples in the temperature range, studied under cooling conditions, revealed a single ionic transport mechanism, probably associated to the in-between [TiO5] layers ion transport. However, a secondary process was observed for non-dried samples, during heating conditions, that could be associated to the ionic transport along the water filled tube's cavity, consistent with SAXS analysis. In summary, this work shows an integral approach, through theory and experiment, in order to understand the effect of the structure on the physical and electronic properties of the system.

A Coverage Prediction Technique for Indoor Wireless Campus Network

The placement of an Access Point (AP) is an important key to determine the spread of the signal. To get the optimal spread of signals, a network designer is required to understand how much coverage an AP can generate. A prediction is given to describe the coverage area produced based on AP placement for the wireless campus network, using a coordinate map modeling based on the real size for the indoor environment. The theoretical approach is used to determine the coverage area of an AP device by testing the function of the distance between the AP and the user. The results show that the signal generated by an AP will cover the entire area that is still on the LOS propagation path. The coverage area generated through AP placement in this case study reached 77.5%. The maximum distance between the AP and the user so that it is within the coverage area is 13.851m. There are still areas that are not covered by the AP, especially for the NLOS propagation path because of the obstruction around the AP.

An Experimental Study of Water BLEVE

A boiling liquid expanding vapor explosion (BLEVE) is an explosion caused by a sudden rupture of a vessel containing a pressurized liquid at a temperature above its boiling point. A BLEVE can occur with all types of liquids and is not a particular phenomenon for flammable liquefied gases such as propane or butane. A particular hazard in the hydrocarbon industry is the use of water at temperatures far above their atmospheric boiling point in steam generation systems. Water is present at high pressure (e.g. 7 MPa) and high temperature (e.g. 300°C). At these conditions the water is superheated and in case of an accidental release the water will undergo a rapid vaporization and a BLEVE type explosion can be expected. This hazard is quit wide spread in all refineries, petrochemical plants, etc. but little data can be found in literature about real size water BLEVE experiments. The aim of this work was to perform BLEVE tests thanks to a 14L pressure vessel designed on purpose to produce high pressure water BLEVE (85 bar). An extended set of pressure gauges was set in the vessel to measure the internal phase change pressure dynamics and around the relief rupture disk to capture the blast wave. Temperature of water was also recorded, and a fast camera (Phantom V2512) was used to see the phenomenon. Data show clearly the pressure recovery in the vessel and multiple blast waves around the vessel. Results are discussed to analyse the risk of water BLEVE.

INFLUENCIA DEL COMPORTAMIENTO VISUAL EN LAS DECISIONES EN EL BLOQUEO DE VOLEIBOL

The purpose of this study was to determine the influence of visual behaviour (visual fixation location, number and duration) on decision-making in volleyball blocking. The visual behavior of 38 volleyball players (23.9 ± 4.2 years), who took part in federated competition, was analyzed with the eye tracking system (Mobile Eye) during visualization of real size video sequences. Regression models show that higher success percentages were obtained when the duration of fixations is low in HC and CB areas, and when the number of fixations increases in BM zone and decreases in CB zone.

A new method for measuring nanoparticle diameter from a set of SEM images using a remarkable point

Scanning Electron Microscopy (SEM) is considered as a reference technique for the determination of nanoparticle (NP) dimensional properties. Nevertheless, the image analysis is a critical step of SEM measuring process and the initial segmentation phase consisting in determining the contour of each nano-object to be measured must be correctly carried out in order to identify all pixels belonging to it. Several techniques can be applied to extract NP from SEM images and evaluate their diameter like thresholding or watershed. However, due to the lack of reference nanomaterials, few papers deals with the uncertainty associated with these segmentation methods. This article proposes a novel approach to extract the NP boundaries from SEM images using a remarkable point. The method is based on the observation that, by varying the electron beam size, the secondary electron profiles crosses each other at this point. First, a theoretical study has been performed using Monte Carlo simulation on silica NP to evaluate the robustness of the method compared with more conventional segmentation techniques (Active Contour or binarization at Full Width at Half-Maximum, FWHM). The simulation results show especially a systematic discrepancy between the NP real size and the measurements performed with both conventional methods. Moreover, generated errors are NP size-dependent. By contrast, it has been demonstrated that a very good agreement between measured and simulated diameters has been obtained with this new technique. As an example, this method of the remarkable point has been applied on SEM images of silica particles. The quality of the segmentation has been shown on silica reference nanoparticles by measuring the modal equivalent projected area diameter and comparing with calibration certificate. The results show that the NP contour can be very accurately delimited with using this point. The measurement uncertainty has been also reduced from 4.3 nm (k = 2) with conventional methods to 2.6 nm (k = 2) using the remarkable point.