Axial Line Research Articles

Motion Attitude Analysis Method of Bullets Based on Field Shadow Image

Aimed at obvious interference noise of shadow images of bullet shot in outside field, and larger extraction error of bullet attitude features of shadow images and other problems, intersection point location method based on axis line and edge is adopted to extract features of bullet tip, and the method based on ellipse fitting is adopted to extract features of bullet tail in the Paper, and then extracted feature information is used to calculate motion attitude of bullets. The method can be applied to shadow image analysis of bullets under field environment well with accurate feature extraction, good consistency and high analysis precision and other features.

Control of flow structures around a cylinder in deep water employing a passive control element

This study aimed to experimentally investigate the swirling flow characteristic in the periphery of a cylinder located vertically in a deep water channel using a particle image velocity measurement method (PIV). In addition to the PIV method, paint visualization experiments were performed to observe the structures of vortical flow qualitatively. Based on the cylinder diameter, Reynolds numbers were changed incrementally as 2.5 × 103, 5 × 103, and 7.5 × 103, while the length of the control element, L = 180 mm was kept constant. The flexible splitter plate made of a plastic material was easily deformed under the influence of vortical flow. In the horizontal plane, taken from the middleheight of the cylinder, instantaneous flow data was measured first. Along these measurements, the distributions and magnitude of the velocity vectors, 〈V〉, vorticity concentrations, 〈ω〉, patterns of streamlines, 〈ψ〉, root mean square of velocity component such as 〈urms〉 and 〈vrms〉, correlations of shear stresses, 〈u′u′〉, 〈v′v′〉 and 〈u′v′〉, turbulent kinetic energy, TKE, and spectral analysis is conducted to define the frequency, f of vortex formations. The presence of a flexible flow control element located along the central axis line of the cylinder significantly affects the vortex formations. The existence of the flexible flow control element can significantly influence the wake flow region. Furthermore, many of the value of flow characteristics decreased as mentioned with respect to the bare case.

Research on lubrication mechanism with fluid–solid coupling of port plate pair in swash plate axial piston pump

When a swash plate axial piston pump operates under high-pressure conditions, the valve plate will undergo warping deformation. Based on the theory of elastic fluid dynamic lubrication, this work establishes a fluid–solid coupling model of a swash plate axial piston pump and solves the governing equations of the lubrication with respect to the port plate pair. Cylinder speed, cylinder angle, fluid viscosity, oil film thickness, seal belt width, and structural parameters are also considered to observe their influence on the valve plate warpage deformation with the swash plate axial piston pump. The results show that the deformation cloud of the valve plate on the axial piston pump is symmetrical, with the axis line of the waist groove as the axis. The deformation of the outer seal zone on the high-pressure side of the valve plate is the largest, and the deformation of the outer seal zone on the low-pressure side of the valve plate is the smallest. Under the same conditions, the material and structure of the valve plate affect the thickness and shape of the oil film. This study provides a theoretical basis for the high pressure of the swash plate axial piston pump.

Upper Cervical Subluxation and Cervicomedullary Junction Compression in Patients with Rheumatoid Arthritis.

ObjectiveRheumatoid arthritis (RA) is known to involve the cervical spine up to 86%. It often causes cervical instability like atlantoaxial subluxation (AAS), subaxial subluxation, and vertical subluxation (VS). In order to find the relation between RA and cord compression, we will evaluate the characteristics and risk factors of basilar invagination (BI) and cervicomedullary junction (CMJ) compression. MethodsFrom January 2007 to May 2015, 12667 patients administrated to Hanyang University Medical Center. Four thousand three hundred eighty-six patients took cervical X-ray and 250 patients took cervical computed tomography or magnetic resonance imaging. Radiologic parameters, medication records were obtained from 242 patients. Multivariate logistic regression analysis was performed with correlation of CMJ compression, basin-dental interval (BDI), basin-posterior axial line interval (BAI), pannus formation, BI, and AAS. ResultsIn the point of CMJ compression, atlantodental interval (ADI), posterior-atlantodental interval, BAI, AAS, and BI are relatively highly correlated. Patients with BI have 82 times strong possibility of radiologic confirmed CMJ compression, while AAS has 6-fold and pannus formation has the 3-fold possibility. Compared to the low incidence of BI, AAS and pannus formation have more proportion in CMJ compression. Furthermore, wrist joint erosion was correlated with VS and AAS. ConclusionBI has a very strong possibility of CMJ compression, while AAS and pannus formation have a high proportion in CMJ compression. Hence bilateral wrist joint erosion can be used as an indicator for the timing of screening test for cervical involvement. We suggest the early recommendation of cervical spine examination for the diagnosis of cervical involvement in order to prevent morbidity and mortality.

Three-dimensional finite element analysis of cantilever fixed bridge supported by implants with mandibular central incisor

Objective: To investigate effect of the contact surface between the bridge and the adjacent teeth on the stress distribution of the implant and bone tissue and the displacement of the prosthesis in the cantilever fixed implant bridge restoring missing mandibular central incisors. Methods: Two-dimensional images of the mandible and dentition in healthy adults were obtained using CT data. A three-dimensional finite element model of cantilever fixed bridge supported by implants with mandibular central incisor was established by computer reconstruction technique.The contact surface between the bridge and the adjacent natural tooth was designed as "oval" and "trapezoid". The "trapezoid" has a slightly smaller median diameter on the labial side and a slightly larger medial diameter on the lingual side. Loading of 120 N was applied on the tangential margin of the middle line of the long axis of the bridge 41. The direction was set at 0°, which was parallel to the long axis of the tooth and downward. The buccal to lingual and downward angles were 30°, 45° and 60°, respectively, perpendicular to the long axis of the tooth and 90° to the lingual side.The stress distribution of the implant and surrounding bone tissue and the displacement of the prosthesis were compared between the two models. Results: Under axial and buccolingual loading, the maximum equivalent stress peak in the implant and surrounding bone tissue in the cantilever with trapezoidal contact surface design and the maximum displacement of the prosthesis were lower. Moreover, the distribution of stress was more balanced and the concentration range of stress was smaller. With the loading angle increasing, this trend was more obvious. When loading angle increased to 90°, the maximum equivalent stress and the maximum displacement of the elliptic contact surface model implant and surrounding bone tissue were 196 and 101 MPa and 0.196 mm, respectively, while the trapezoidal contact surface model were 157 and 72 MPa and 0.164 mm, respectively. Conclusions: The trapezoidal contact surface of the bridge and the adjacent teeth in the cantilever fixed bridge supported by implants with mandibular central incisor is beneficial to reduce the impact of the leverage on the implant and surrounding bone tissue.

Experimental and theoretical investigation of the boiling heat transfer in a low-pressure natural circulation system

The implementation of passive safety systems in nuclear reactors provides the opportunity to enhance the nuclear safety. On the other hand, an accurate and reliable prediction of the heat removal behavior is not ensured because the operating conditions of certain types of passive systems like containment cooling systems differ from the validity ranges of the established heat transfer correlations. Therefore, a generic and detailed investigation is still necessary for passive systems. Against this background, the test facility GENEVA was erected at Technische Universitat Dresden in 2012. Since the commissioning, generic experiments concerning the system and stability behavior of this facility, which emulate a low-pressure and low-flow (LPLF) natural circulation system, were provided. Nevertheless, the investigation of the heat transfer behavior remained an open issue. On this account, the instrumentation in the heat transfer region inside GENEVA was improved to gather the necessary temperature and void fraction profiles. The performed experiments provide a generic and wide database concerning boiling in a LPLF natural circulation systems. Within this paper, the development of the wall and bulk fluid temperature as well as the axial and center line void fraction profile in a slightly inclined tube for different heat flow rates are discussed. Furthermore, flow patterns could be identified on behalf of the void fraction measurements. To conclude the experimental analysis, the development of the heat transfer coefficient was estimated. These experimental data provide the basis for a simulation with the lumped-parameter thermal-hydraulic code ATHLET and serve as validation reference. However, the comparisons between the experimental and computational results show insufficient agreements. Mainly, the simulation misses the saturation point of the experiments, which leads to great differences of the void fraction values. Moreover, inaccuracies appear as well with the heat transfer coefficient. The experimental and computational results that are discussed in this paper provide the basis for the advancement not only of heat transfer correlations but also of flow pattern maps within the range of low pressure natural circulation system. In summary, this investigation contributes to the general purpose to enhance nuclear safety by providing an accurate and reliable prediction o f the heat removal capacity of passive systems.

Diffractive gratings with varying period’s shape

Diffractive gratings with varying period’s shape

Effect of the coordinate frame on high-order expansion of serial-chain displacement

An algorithmic differentiation technique gives a simpler, faster power series expansion of the finite displacement of a closed-loop linkage. It accomplishes this by using a higher order than what has been implemented by complicated prior formulas for kinematic derivatives. In this expansion, the joint rates and axis lines generate the instantaneous screw of each link. Constraining the terminal link to have a zero instantaneous screw satisfies closure. In order to maintain closure over a finite displacement, it is necessary to track the spatial trajectory of each joint axis line, which in turn is directed by the instantaneous screw of a link to which it is attached. Prior algorithms express these screws in a common ground-referenced coordinate frame. Motivated by the kinematics solver portion of the recursive Newton–Euler algorithm, an alternative formulation uses sparse matrices to update the instantaneous screw between successive link-local frames. The recursive Newton–Euler algorithm, however, conducts the expansion to only second order, where this paper shows local coordinate frames that are only instantaneously aligned with their respective links give identical expressions to those in frames that move with the links. Moving frames, however, require about 40% of the operations of the global-frame formulation in the asymptotic limit. Both incrementally translated (Java) and statically compiled (C++) software implementations offer more modest performance gains; execution profiling shows reasons in order of importance (1) balance of calculation tasks when below the asymptotic limit, (2) Java array bounds checking, and (3) hardware acceleration of loops.

Electric Field Computation in Unbounded Domain Using Axial Green Function Method

Since the numerical computation in unbounded domains has many limitations using the traditional discretization methods, it is necessary to develop an efficient method that can handle the infinite boundary problem. The axial Green function method (AGM) is eligible to implant the prescribed asymptotic behavior of the solution at the far field into the bounded computational domain. The axial line in AGM plays a key role in discretizing the differential equation in association with 1-D Green function. In case of unbounded domain, we have to consider the infinite axial line that is a half-infinite line parallel to an axis. We define a particular type of 1-D Green function on this infinite axial line corresponding to the elliptic problem, which is called the infinite axial Green function. Based on the new feature of this Green function, we derive the representation formula of the solution on the infinite axial line. Using this formula, we can translate the far-field asymptotic behavior with undetermined coefficient into the forcing term in the bounded computational domain. The efficiency and accuracy of this approach are fully investigated by taking numerical examples.

Effect of Lower Extremity Static Alignment on Dynamic Valgus in Adolescents Following ACL Reconstruction

PURPOSE: Knee abduction moments may lead to valgus collapse, potentially causing ACL rupture. The contribution of static lower extremity alignment to knee abduction moments is unknown. This study assessed relationships among lower extremity static alignment and dynamic kinematics and kinetics during side-step cutting in uninjured adolescent athletes. METHODS: This retrospective study included 8 adolescents with recent unilateral ACL reconstruction (mean age 14.8 yr, SD 1.2; 3/8 female). Frontal plane hip to ankle imaging (EOS) was used to measure mechanical axis deviation (perpendicular distance from the center of the femoral condyles to the mechanical axis line connecting the center of the femoral head to the center of the talar dome) and tibial-femoral angle. 3D motion capture provided lower extremity kinematics and kinetics during quiet standing and loading (initial contact to peak knee flexion) of an anticipated 45° side-step cut; 2-3 trials per limb were averaged for analysis. Relationships among imaging, static motion capture and dynamic motion capture measures were investigated using correlation, and backward stepwise linear regression was used to evaluate potential predictors of average dynamic knee abduction moment. RESULTS: Regardless of surgical status, standing knee abduction angle was correlated with standing hip adduction (r=0.60, p=0.02) and ankle eversion (r=0.85, p<0.0001) along with larger mechanical axis deviations (r=0.83, p=0.0001) and higher knee abduction on EOS (r=0.44, p=0.09). Dynamic knee abduction moment was best predicted by a combination of EOS knee abduction angle, standing ankle eversion, standing knee abduction, standing knee rotation, ankle eversion during cutting, along with ground reaction force and age (R2=0.94; p<0.004). There was no significant relationship between knee abduction moment and side (surgical vs. contralateral) (p=0.63). CONCLUSIONS: In this small group of adolescent athletes with recent ACLR, knee abduction moment during side-step cutting was related to age and anatomic lower limb alignment in addition to dynamic factors such as ankle positioning and ground reaction force. Anatomic alignment or standing posture with greater hip adduction, knee abduction, and ankle eversion may indicate a higher risk for injury during dynamic activities.

A Novel Gear Honing Machine Parameter Design and Finite Element Analysis Based on the Principle of Dislocation Axis Line Contact

The characteristics of the dislocation axis line contact gear space transmission was analyzed in order to study the new precision gear honing machine prototype which could be clamped and formed at one time, and a pair of dislocation axis involute helical gears in space was designed from the most basic principle of involute gear meshing. The vertical dislocation axis line contact the worm and worm gear (helical gear) transmission mechanism were formed, when two gears had equalent normal base diameter and the sum of their base-circle spiral angles was equal to 90°. According to worm drive relationship of the vertical dislocation axis line contact, the helical gear tooth surface was honed through the worm could be used as a grinding wheel of the honing machine. Grinding wheels with different parameters could be used to machine bevel gears with different modulus, different numbers of teeth and different tooth widths. The finite element analysis and optimization showed that the prototype of the machine tool was reasonable, and the first-order natural frequency is 341.8Hz, which was much higher than the working frequency of 30Hz to avoid resonance.

DEVELOPMENT OF MEASURES TO CREATE A SYSTEM OF COORDINATE-TIME PROVISION OF UKRZALIZNYTSIA WORK BY GEODETIC METHODS

Providing high-speed motion in railways is impossible without the use of the latest achievements of measurements, communications and informations technologies. Therefore, to address this issue, on the introduction of advanced technology, the authors of this publication, the proposed System of Coordinate-Time Provision of Ukraine Railways. This system is roughly divided into three major segments: normative and methodological, equipments and logistics, communications and information. Describe the segments, which includes instructions, measuring instruments, means of transmission and processing of measurement results and more. In this article is provides a comparative analysis of the existing system of coordinates, and proposed a new coordinate system convenient for the Ukraine Railways. Conditional coordinate system USKU-20XX – rectangular coordinate system associated with ITRF2015, and Gauge coordinate system KSKU-20XX in which the horizontal axis is approximated, to a certain epoch, axis of the track and the axis is the distance from the axis lines perpendicular to it. These two systems give opportunity quickly, accurately and uniquely identify the position of the track and another objects, both in a horizontal plane and in space. The methods and accuracy of the coordinates of the geodetic network, track and other facilities was valuated too.

Design of a spiral inflector and transverse beam matching for K130 cyclotron at the Variable Energy Cyclotron Centre

This paper describes the design of a spiral inflector for inflecting heavy ion beams into the existing central region of the $$\text {K} = 130$$ Variable Energy Cyclotron at Kolkata. Simulation results of transverse beam dynamics through the spiral inflector and the effect of the fringe field on beam phase ellipses at its exit have been discussed in the absence of space charge effect. We have also made an effort to minimise the effect of inflector fringe field by properly adjusting the inflector voltage. The proper matching conditions in the central region have been obtained by optimising the system parameters of the existing axial injection line of K130 cyclotron. The tracking of particles that belong to the boundary of the optimised phase ellipses at the matching point has also been carried out in the computed electric and magnetic fields in the central region. Simulation results confirm that the optimised beam condition reduces beam losses for further acceleration in the cyclotron.

A Liutex based definition and identification of vortex core center lines

Six core issues for vortex definition and identification concern with (1) the absolute strength, (2) the relative strength, (3) the rotational axis, (4) the vortex core center, (5) the vortex core size, and (6) the vortex boundary (Liu C. 2019). However, most of the currently popular vortex identification methods, including the Q criterion, the λ2 criterion and the λci criterion et al, are Eulerian local region-type vortex identification criteria and can only approximately identify the vortex boundary by somewhat arbitrary threshold. On the other hand, the existing Eulerian local line-type methods, which seek to extract line-type features such as vortex core line, are not entirely satisfactory since most of these methods are based on vorticity or pressure minimum that will fail in many cases. The key issue is the lack of a reasonable mathematical definition for vortex core center. To address this issue, a Liutex (previously named Rortex) based definition of vortex core center is proposed in this paper. The vortex core center, also called vortex rotation axis line here, is defined as a line where the Liutex magnitude gradient vector is aligned with the Liutex vector, which mathematically implies that the cross product of the Liutex magnitude gradient vector and the Liutex vector on the line is equal to zero. Based on this definition, a novel three-step method for extracting vortex rotation axis lines is presented. Two test cases, namely the Burgers vortex and hairpin vortices, are examined to justify the proposed method. The results demonstrate that the proposed method can successfully identify vortex rotation axis lines without any user-specified threshold, so that the proposed method is very straightforward, robust and efficient.

Flow over a symmetrically curved circular cylinder with the free stream parallel to the plane of curvature at low Reynolds number

Three-dimensional flow past a symmetrically curved circular cylinder with the free stream parallel to the plane of curvature is numerically investigated by high-order spectral element method. The axial line of the cylinder is described in Cartesian coordinates as y=A[cosh(x∕A)−1] with A being a catenary coefficient used to scale its span ratio. In this geometry configuration, the deformed cylinder can be divided into two half segments, respectively of the convex segment in the upstream and the concave segment in the downstream. Different span ratios are investigated with respect to A=0.5∼10. It is found that four wake topologies, namely of single body, bi-stable, vortex impingement and steady wakes, are successively appeared with the increase of the span ratio. By examining the flow field quantities including mean and fluctuation of velocities and pressure along the axial line, some important characteristics of axial flow dynamics are intensively revealed. Most interestingly, the generation of axial flow along the curved surface of the cylinder is strongly influenced by not only the curvature ratio but also the wake interference effects.

Vortex axis tracking by iterative propagation (VATIP): a method for analysing three-dimensional turbulent structures

Vortex is a central concept in the understanding of turbulent dynamics. Objective algorithms for the detection and extraction of vortex structures can facilitate the physical understanding of turbulence regeneration dynamics by enabling automated and quantitative analyses of these structures. Despite the wide availability of vortex identification criteria, they only label spatial regions belonging to vortices, without any information on the identity, topology and shape of individual vortices. This latter information is stored in the axis lines lining the contours of vortex tubes. In this study, a new tracking algorithm is proposed which propagates along the vortex axis lines and iteratively searches for new directions for growth. The method is validated in flow fields from transient simulations where vortices of different shapes are controllably generated. It is then applied to statistical turbulence for the analysis of vortex configurations and distributions. It is shown to reliably extract axis lines for complex three-dimensional vortices generated from the walls. A new procedure is also proposed that classifies vortices into commonly observed shapes, including quasi-streamwise vortices, hairpins, hooks and branches, based on their axis-line topology. Clustering analysis is performed on the extracted axis lines to reveal vortex organization patterns and their potential connection to large-scale motions in turbulence.

Analysis of the discrepancy of crown-root morphology of central incisors among different skeletal malocclusion using cone-beam CT

Objective: To investigate the discrepancy of crown-root morphology of upper and lower central incisors in adult patients with different skeletal malocclusions using cone-beam CT (CBCT). Methods: Patients visiting the Department of Orthodontics, College of Stomatology, Xi'an Jiaotong University from January 2015 to December 2017 were selected, including 108 cases (52 males, 56 females, aged from 18 to 30 years, mean age 25.8 years). According to CBCT data and cephalometric analysis, 66 patients with average angle were selected as the sagittal skeletal group, including 24 Class Ⅰ patients, 20 Class Ⅱ and 22 Class Ⅲ patients. In the other selected 66 skeletal Class Ⅰ patients including 21 low angle patients, 24 average angle patients (from the sagittal skeletal Class Ⅰ subgroup) and 21 high angle patients. Invivo 5 software was used to locate the CBCT image three dimensionally and then obtain the middle labio-lingual section of right central incisor. Auto CAD 2007 software was applied to measure the angle formed by the long axis of root and the extension line of the long axis of crown (Collum angle), and the angle between the long axis of crown and the lip tangent line passing through the center of the labial surface of crown (labial surface angle). One-way ANOVA and Scheff were used to analyze the discrepancies among classifications and Pearson correlation analysis was used to determine the correlation between the Collum angles and labial surface angles. Results: Significant differences were found in Collum angles and labial surface angles among different sagittal skeletal patterns (P<0.05). The Collum angle of maxillary central incisors in Class Ⅱ patients was 5.18°±4.97° and the average labial surface angle was 17.78°±3.74°, which were both significantly higher than that of maxillary central incisors in Class Ⅰ and Ⅲ subgroups (P<0.05). Similarly, the above two angles of mandibular central incisors in Class Ⅲ were 5.59°±5.64° and 15.32°±3.05°, which were significantly higher than that of mandibular central incisors in Class Ⅰ and Ⅱ subgroups (P<0.05). There was no significant difference among different vertical skeletal patterns (P>0.05). Notably, the Collum angles of maxillary or mandibular central incisors presented significantly positive correlation with labial surface angles (maxillary: r=0.723, P<0.001; mandibular: r=0.752, P<0.001). Conclusions: The long axis of the crown of the maxillary central incisor in skeletal Class Ⅱ patients and the mandibular central incisor in skeletal Class Ⅲ patients are obviously deviated toward the lingual side relative to the long axis of the root, and correspondingly there is a greater labial surface angle of the crown, which indicates that equivalent positioning deviation during bracket bonding can cause greater torque expression error.

Relationship between intercondylar notch angle and anterior cruciate ligament injury: a magnetic resonance imaging analysis

ObjectivesThis study was performed to compare the intercondylar notch angle (INA) and tibial slope in patients with and without anterior cruciate ligament (ACL) injury and determine the risk factors and influence of these anatomic variations on ACL injury.MethodsParticipants with and without non-contact ACL injuries were included in the patient and control groups, respectively. The INA (formed by the femoral axis and Blumensaat line), lateral tibial slope (LTS), and medial tibial slope (MTS) were measured on magnetic resonance images. Comparisons were performed between the two groups. A binary logistic regression model was used to determine the influence of the variables on ACL injury.ResultsFifty-two participants were included in each group. The INA was significantly smaller and the LTS was significantly greater in the patients than in the controls. No difference was found in the MTS between the two groups. The area under the receiver operating characteristic curve for the combination of the INA and LTS was 0.776 (95% confidence interval, 0.688–0.864).ConclusionsThe INA was smaller and the LTS was greater in patients with than without ACL tears. The INA in combination with the LTS could be used to predict ACL injury.

Lateral femoral sliding osteotomy in total knee arthroplasty with valgus deformity greater than twenty degrees.

Lateral femoral sliding osteotomy has been reported as an effective technique for total knee arthroplasty (TKA) with significant valgus deformity. This study aims to investigate its utility in TKA with valgus deformity greater than 20°, for which few studies have examined. Consecutive TKA patients with valgus deformity treated with the sliding osteotomy at our institution were retrospectively studied. Constraint implants were not used. Radiological and clinical parameters at follow-ups were compared with those pre-operatively. Radiological parameters included the hip-knee-ankle angle (HKA), the anatomical lateral distal femoral angle (aLDFA), the anatomical lateral plateau ankle angle (aLPTA), and the angle between the femoral mechanical axis and transepicondylar line (femoral transepicondylar angle, FTEA) which was used to reflect concurrent extra-articular valgus and corresponding local alignment. Clinical outcome measures included the Knee Society Score and Functional Score. Twenty-five patients operated on between July 2011 and February 2017 were enrolled. The average follow-up time was 3.3 (1.5~7.9) years. The pre-operative HKA of 202.7 ± 2.3° (equivalent to valgus of 22.7 ± 2.3°) was reduced to 180.4 ± 2.3° at final follow-ups (P < 0.001). The aLFDA, aLPTA, and FTEA were all significantly improved, with the last one increased from 84.2 ± 1.8° to 89.6 ± 1.6° (t = - 11.35, P < 0.001). All clinical scores were significantly improved without major complications. Lateral femoral sliding osteotomy can be effective and safe for TKA with severe valgus deformity greater than 20°.

Atomization parameters and fire suppression characteristics of water mist in simulated roadway

Water mist is considered to be one of the most effective ways to suppress fire in coal mines. The structure of an atomization device for water mist was determined based on preliminary research. By regulating the working conditions, including air pressure and water flow volume, we obtained water mist with varying particle size distributions, which proved to be the most important factor for fire suppression. Particle size distribution, characterized by a V99 and V50, changed from 50 to 1600 µm during the experiment at a given air pressure (0.6–0.16 MPa) and water flow volume (0.6–1.0 m3/h). The particle size distribution along an axial line can be divided into a wavy flow zone and a fully atomizing zone. Based on the experiments, three types of particle size distributions, 98, 498 and 1013 µm, were used to test the fire-suppression characteristics of water mist in a simulated roadway with a self-built platform. The result showed that water mist could suppress fire rapidly and the highest temperature dropped from 205 to 10 °C within 30 s.