JVE International
Not a member yet
1200 research outputs found
Sort by
Experimental study on creep wetting of silty clay
Get PDFTo study the wetting of a silty clay subgrade in an expressway, many laboratory tests were carried out. The test results show that the creep deformation of silty clay under water immersion cannot be ignored, but it is different from the deformation caused by wetting. The creep properties of soil mass are affected by many factors. Under different stress conditions, the soil mass will show different properties. In order to study the creep characteristics of silty clay in Chongqing under water wetting and different stress levels, a series of triaxial water wetting creep tests were carried out. The Singh-Mitchell creep equation was introduced to establish the creep model of silty clay drainage in Chongqing, and the parameters of the model were discussed
Cephalometric components and their implications in mandibular positioning
Get PDFThe mandibular position is determined by several physiological factors, which should be considered for diagnosis, therapy and stability. Sixty-eight lateral skull radiographs were taken and plotted to determine the relationship of the occlusal plane with the mandibular position among others. A Spearman statistical analysis was performed to determine the relationship between these variables. The occlusal plane showed a statistically significant correlation with mandibular position
Study of skeletal changes in individuals with anterior open bite treated with JFO
Get PDFAnterior Open Bite (AOB) is a type of malocclusion that promotes severe esthetic aesthetic and functional impairment. Its etiology is multifactorial and may involve several etiological factors, such as deleterious oral habits, hypertrophic tonsils, mouth breathing, dental ankylosis and eruption abnormalities either associated with genetic factors or not. AOB is one of the most challenging treatments in any treatment protocol. A retrospective study of 21 patients with anterior open bite treated with Jaw Functional Orthopedics (JFO) with improvement in overbite was conducted with the aim of understanding mandibular behavior during the treatment. Using SPSS 11.0, using Shapiro-Wilk test all variables showed Normal distribution (p> 0.05), in the comparison between the means at T0 and T1, the t-test for paired samples was used. In order to verify whether cooperative patients had better results than the non-cooperative group, a variable was created. For all tests, a significance level of 5 % was used. A weak statistical correlation (P< 0,1) was found for Bimler’s Factor 8. Change resulted from AOB treatment with FOA in a short time. There was no statistical correlation of Bimler’s Factor 8 when cooperative patients were compared with the non-cooperative group. It could be concluded that in the studied sample there was a weak correlation between overbite improvement during AOB treatment with JFO and mandibular rotation. Further studies are necessary to understand the skeletal behavior of the maxillary bones in the treatment of AOB with FOA
Nonlinear dynamic behavior analysis of bridge pier impacted by a moving barge
Get PDFThe contradiction between ships and bridges is becoming increasingly prominent, and ship-bridge collision accidents occur frequently. However, the existing researches focus on the impact force, the bridge will be simplified to a single pier, but the single pier collision model cannot accurately reflect the dynamic behaviors and damage evolution process of collision. In order to solve this problem, a refined barge-whole bridge collision finite element model is established. This model can be used to analyze the dynamic characteristics of barge and whole bridge collision. According to finite element results, the impact force can be divided into four phases: (1) Linear elastic phase, (2) Buckling unstable phase, (3) Plastic deformation phase and (4) Unloading phase. The impact velocity and barge mass change the initial kinetic energy of the barge, which is positively correlated with the peak impact force and the duration of the impact force. Compared with the barge-single pier collision model, the barge-whole bridge collision model is more systematic and comprehensive in reflecting the dynamic behavior of collision. In this paper, the research of barge-bridge collision provides a scientific basic theoretical basis for the design of anti-collision facilities, the proposal of post-collision damage assessment techniques and the development of bridge post-collision warning system
Indoor and outdoor multi-source 3D data fusion method for ancient buildings
Get PDFAncient buildings carry important information, such as ancient politics, economy, culture, customs. However, with the course of time, ancient buildings are often damaged to different degrees, so the restoration of ancient buildings is of great importance from the historical point of view. There are three commonly used non-contact measurement methods, including UAV-based oblique photogrammetry, terrestrial laser scanning, and close-range photogrammetry. These methods can provide integrated three-dimensional surveys of open spaces, indoor and outdoor surfaces for ancient buildings. Theoretically, the combined use of the three measurement methods can provide 3D (three-dimensional) data support for the protection and repair of ancient buildings. However, data from the three methods need to be fused urgently, because if the image data is not used, it will lead to a lack of real and intuitive texture information, and if only image matching point clouds are used, their accuracy will be lower than that of terrestrial laser scanning point clouds, and it will also lead to a lack of digital expression for components with high indoor historical value of ancient buildings. Therefore, in this paper, a data fusion method is proposed to achieve multi-source and multi-scale 3D data fusion of indoor and outdoor surfaces. It takes the terrestrial laser point cloud as the core, and based on fine component texture features and building outline features, respectively, the ground close-range image matching point cloud and UAV oblique image matching point cloud are registered with the terrestrial laser point cloud. This method unifies the data from three measurements in the point cloud and realizes the high-precision fusion of these three data. Based on the indoor and outdoor 3D full-element point cloud formed by the proposed method, it will constitute a visual point cloud model in producing plans, elevations, sections, orthophotos, and other elements for the study of ancient buildings
Effect of damping ditch on blasting vibration reduction by field experiment and numerical simulation
Get PDFIn order to analyze the influence of a damping ditch on the blasting vibration, a large number of on-site monitoring tests with or without damping ditch were carried out based on the foundation pit excavation project. Based on the Sadovsky’s empirical formula, the optimized vibration velocity attenuation model was established by using the waveform subsection correspondence method and least square method. The calculation results are in good agreement with the measurement results. The average errors in radial direction and vertical direction are 17.04 % and 10.76 % respectively. A series of finite element models were established to study the influence of the damping ditch geometry on the damping effect. The experimental and numerical results show that the damping ditch can obviously reduce the blasting seismic effect, with the highest damping ratio in the area near blasting source. For different damping ditches, the damping ratio first increases and then decreases proportionally to the increase of distance between the measuring point and the blasting zone. The damping ditch depth has the best damping effect on blasting vibration, followed by the distance between the damping ditch and the blasting source, and finally the damping ditch width, which is consistent with the damping mechanism of theoretical analysis. The attenuation of the surface wave is only related to the damping ditch depth. The research results can provide a reference for the design of blasting vibration isolation
Dynamic characteristic research on a simulated sugarcane field exciter for small sugarcane harvesters: simulations and experiments
Get PDFThe sugarcane harvester vibration has a bad effect on the sugarcane cutting quality. The effect of sugarcane field roughness on the sugarcane harvester vibration is much more significant than those of cutting forces and the engine. In order to simulate sugarcane field roughness, a simulated sugarcane field exciter (SSFE) was developed to actuate a self-developed sugarcane harvester experiment platform (SHEP). The dynamics and the mathematical models of the SHEP were established. Simulations of the mathematical model show these two models are reasonable. The dynamic characteristic experiment of the SSFE shows it matches characteristics of sugarcane field roughness, but great lateral oscillations existed when it worked. Then the SSFE II was developed. The dynamic characteristic experiment of the SSFE II shows it matches characteristics of sugarcane field roughness and improves the SSFE. The modal test of the SHEP was done to further study dynamic characteristics of the SSFE II. With the SSFE II, simulated experiments of sugarcane harvesters under complete vibration causing conditions can be done in labs instead of sugarcane fields to avoid the low efficiency, poor security and bad reliability during experiments in sugarcane fields
Test and mechanism analysis for crack propagation by blasting in rock under the condition of unidirectional load
Get PDFIn deep rock blasting, there are different constraint conditions such as unidirectional loading, bidirectional loading and tridirectional loading due to in-situ stress. The similar model test of rock blasting under unidirectional load was carry out to study the law of crack propagation in rock by blasting in this study. A transparent material which conformed to the mechanical properties of hard rock is used to make specimens. A high-speed camera was used in some model blasts. After blasting the surface cracks on the specimen were measured, including the near zone and middle zone of blasting. The results showed that: (1) the radial main cracks in the specimens under initial static load propagated along the principal stress direction, which is different from that without initial stress, and there is almost no radial main crack in the direction perpendicular to the principal stress. (2) The average length of radial crack and diameter of circumferential fracture circle gradually decrease with the increase of unidirectional initial stress, but the diameter of compression crushing circle increase. (3) The maximum and average initial velocity of radial crack growth decrease with the increase of unidirectional initial stress
Research on dynamic and vibration behaviors of a flip-flow screen with crankshaft-link structure
Get PDFA flip-flow screen with crankshaft-link structure (FFSCLS) is an effective solution for screening of high-water and fine materials due to its good performance. The dynamical characteristics largely affects the screen performance and the processing capacity of the FFSCLS. In this paper, a dynamic model governing the dynamical characteristics of the FFSCLS was proposed. In addition, the motion trajectory and vibration data of the FFSCLS were investigated by vibration experimental technology. The results show that the experiment results can be fully described by the dynamic model whit the maximum deviation was within 6.26 %. Moreover, the mass ratio between outer box and inner box determined the dynamical characteristics of the flip-flow screen, and these parameters should be optimized. This work can provide useful references for efficient operation and optimal design for the flip-flow screen
Structure and movement, let’s not kill Chronos
Get PDFThe myth of Chronos that devours his children is the allegorical expression of time that ends everything, but there is another reading: that time exists and allows us to understand the idea of a process, of evolution, both biologically and in any other aspect of life. The structure is the static, current, measurable morphological expression of everything that has a physical manifestation. Movement is the expression of life that is inexorably written on the structure and is responsible for its dynamism and change. We have developed the ability to analyse the structure in a systematic and detailed way, isolating it from time, and therefore depriving it of the movement that animates it, fixing the moment with static photographic images. With direct cephalometric techniques or on radiography we have defined points and reference systems, measured, compared, made proportions, and described the layout. Like the Art, the Morphological Sciences evolve from a two-dimensional vision to a three-dimensional one and we have given importance to empty spaces. But unlike art, we have difficulty internalizing and becoming aware of movement and the vital energy that animates it. Studying Movement means studying Form along Time. Structure and Function are two sides of the same coin, and our field is a clear example of this. We cannot work on occlusion without understanding the functions associated with the whole system: breathing, swallowing, chewing, are the main sources of stimuli responsible for the development of the Stomatognathic System, which has the movement as its main engine. In our clinical practice we are convinced that seeking an integration between Form and Function provides balance and health to the system and therefore delays the negative effects of Time, and coherently understanding the Form-Function-Time triad provides a broader understanding of development and balance of our system