Flame image velocimetry analysis of reacting jet flow fields with a variation of injection pressure in a small-bore diesel engine

This study measures in-flame flow fields in a single-cylinder small-bore optical diesel engine using Flame Image Velocimetry (FIV) applied to high-speed soot luminosity movies. Three injection pressures were tested for a two-hole nozzle injector to cause jet-wall interaction and a significant jet-jet interaction within 45° inter-jet spacing. The high-pressure fuel jets were also under the strong influence of a swirl flow. For each test condition, soot luminosity signals were recorded at a high framing rate of 45 kHz with which the time-resolved, two-dimensional FIV post-processing was performed based on the image contrast variations associated with flame structure evolution and internal pattern change. A total of 100 combustion events for each injection pressure were recorded and processed to address the inherent cyclic variations. The ensemble-averaged flow fields were used for detailed flow structure discussion, and Reynolds decomposition using a spatial filtering method was applied to obtain high-frequency fluctuations that were found to be primarily turbulence. The detailed analysis of flow fields suggested that increased injection pressure leads to enhanced jet flow travelling along the bowl wall and higher flow vectors penetrating back towards the nozzle upon the impingement on the wall. Within the jet-jet interaction region, the flow vectors tend to follow the swirl direction, which increases with increasing injection pressure. The FIV also captured a turbulent ring vortex formed in the wall-jet head, which becomes larger and clearer at higher injection pressure. A vortex generated in the centre of combustion chamber was due to the swirl flow with its position being shifted at higher injection pressure. The bulk flow magnitude indicated significant cyclic variations, which increases with injection pressure. The turbulence intensity is also enhanced due to higher injection pressure, which primarily occurs in the wall-jet head region and the jet-jet interaction region.

Object tracking using motion flow projection for pan-tilt configuration

We propose a new object tracking model for two degrees of freedom mechanism. Our model uses a reverse projection from a camera plane to a world plane. Here, the model takes advantage of optic flow technique by re-projecting the flow vectors from the image space into world space. A pan-tilt (PT) mounting system is used to verify the performance of our model and maintain the tracked object within a region of interest (ROI). This system contains two servo motors to enable a webcam rotating along PT axes. The PT rotation angles are estimated based on a rigid transformation of the the optic flow vectors in which an idealized translation matrix followed by two rotational matrices around PT axes are used. Our model was tested and evaluated using different objects with different motions. The results reveal that our model can keep the target object within a certain region in the camera view.

Retinal optic flow during natural locomotion

We examine structure of visual motion on the retina during natural locomotion in real world environments. We demonstrate that eye-movement-free/head-centered optic flow is highly unstable due to the complex, phasic head movements that occur throughout the gait cycle. In contrast, VOR-mediated retinal optic flow has stable, reliable features that may be valuable for the control of locomotion. In particular, the sign and magnitude of the curl of retinal flow at the fovea specifies the degree to which a walker will pass to the left or right of their fixation point. In addition, the peak in the divergence of the retinal flow field specifies the walker's overground velocity/momentum vector in retinotopic coordinates. If we assume a walker can reliably determine the body-relative position of their fixation, this retinotopic cue for their body's momentum could be an essential aspect of the visual control locomotion over complex terrain.Clickable Video Links (Click here for a playlist of all videos)https://www.youtube.com/playlist?list=PLWxH2Ov17q5HRHVngfuMgMZn8qfOivMafVideo 1. Gaze Laser Skeleton – Video (Full Speed) – Free Walking – Raw (See Figure 1)Video 2. Gaze Laser Skeleton – Video (1/4 Speed) – Free Walking – Optic Flow VectorsVideo 3. Gaze Laser Skeleton – Video (1/4 Speed) – Free Walking – Optic Flow StreamlinesVideo 4. Sim. Eye Trajectory – Sim. Retinal Flow – Fixation Aligned with PathVideo 5. Sim. Eye Trajectory – Sim. Retinal Flow – Fixation to Left of PathVideo 6. Sim. Eye Trajectory – Sim. Retinal Flow – Fixation to Right of PathVideo 7. Sim. Eye Trajectory – Sim. Retinal Flow – Vertical Sin WaveVideo 8. Sim. Eye Trajectory – Sim. Retinal Flow – Horizontal Sin WaveVideo 9. Sim. Eye Trajectory – Sim. Retinal Flow – CorckscrewVideo 10. Gaze Laser Skeleton – Sim. Retinal Flow – Ground LookingVideo 11. Gaze Laser Skeleton – Video (Full Speed) – Rocky Terrain – RawVideo 12. Gaze Laser Skeleton – Video (1/4 Speed) – Rocky Terrain – Optic Flow StreamlinesVideo 13. Gaze Laser Skeleton – Sim. Retinal Flow – Rocky TerrainVideo 14. Quadcopter Gimbal – Video (Full Speed) – Optic Flow Streamlines

Application of Finite Element Power Flow and Visualization in Rolling Mill Vibration

The power flow harmonic responses of the upper roll system are obtained by combining the speed solution and stress solution, and compare with the traditional harmonic response, we find that the traditional vibration displacement, velocity and acceleration harmonic response spectrum can’t completely reflect the reality of the vibration energy. The power flow vectors of the mill can be obtained with a color vector program developed independently. Compared with the vibration displacement vectors, we found that the displacement vector distribution of the mill is quite different from that of the power flow vector with the frequency of 104Hz: the displacement vector amplitude gradually increases from the bottom to the top of the mill, and the displacement vector is transmitted from bottom to top vertically. The power flow vector amplitude of the working roll and the intermediate roll is larger than that of the other parts, and power flow vectors present complex transfer directions. Similarly, when the considering frequency is taken as other values, the distribution of vibration displacement vector and power flow vector are also variable.

Determining Land Management Zones Using Pedo-Geomorphological Factors in Potential Degraded Regions to Achieve Land Degradation Neutrality

The proper delineation of site-specific management zones is very important in the agricultural land management of potentially degraded areas. There is a necessity for the development of prospective tools in management plans to correctly understand the land degradation processes. In order to accomplish this, we present a pedo-geomorphological approach using soil texture, land elevation and flow vector aspects to distinguish different management zones and to discretize soil micronutrients. To achieve this goal, we conducted the study in the Neyshabur plain, Northeast Iran. For data collection, grid sampling (500 × 500 m) was used with 70 specific points. Soil samples were collected in triplicates from various sites as composite samples (0–30 cm) to analyse clay, Zn, Mn, Cu and Fe. Using the altitude information (obtained with GPS at each sampling point), flow vectors were also modelled for all selected points. Based on the values of altitude, flow vectors and clay, management zones were delimited using geographic information systems. The best data organization was obtained from the combination of clay + elevation + flow vector attributes, generating two different management zones. In this circumstance, the lowest fuzzy performance index (FPI) and modified partition entropy (MPE) values were generated. It can be observed that the management zone 1 (MZ1) is located in the areas with a lower elevation and higher content of clay. On the other hand, the MZ2 was characterized by areas with a higher elevation and lower clay content. This study concluded that the design of management zones, using pedo-geomorphological information could reduce the time and cost of sampling necessary to assess potentially degraded areas of land.

A novel accuracy assessment model for video stabilization approaches based on background motion

In this paper, we propose a new accuracy measurement model for the video stabilization method based on background motion that can accurately measure the performance of the video stabilization algorithm. Undesired residual motion present in the video can quantitatively be measured by the pixel by pixel background motion displacement between two consecutive background frames. First of all, foregrounds are removed from a stabilized video, and then we find the two-dimensional flow vectors for each pixel separately between two consecutive background frames. After that, we calculate a Euclidean distance between these two flow vectors for each pixel one by one, which is regarded as a displacement of each pixel. Then a total Euclidean distance of each frame is averaged to get a mean displacement for each pixel, which is called mean displacement error, and finally we calculate the average mean displacement error. Our experimental results show the effectiveness of our proposed method.