Micromachining for sub-10nm flying height sliders

2005 ◽  
Author(s):  
Mingsheng Zhang ◽  
L. Gonzaga ◽  
Yuet Sim Hor ◽  
Bo Liu
Keyword(s):  
Flying Height

scholarly journals A Convolutional Neural Network-Based Method for Corn Stand Counting in the Field

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 507
Author(s):  
Le Wang ◽  
Lirong Xiang ◽  
Lie Tang ◽  
Huanyu Jiang
Keyword(s):  
Frame Rate ◽  
Flying Height ◽  
Battery Life ◽  
Growth Stages ◽  
Camera Motion ◽  
Long Duration ◽  
Manual Counting ◽  
Detection And Counting ◽  
Plant Image ◽  
Early Seedling

Accurate corn stand count in the field at early season is of great interest to corn breeders and plant geneticists. However, the commonly used manual counting method is time consuming, laborious, and prone to error. Nowadays, unmanned aerial vehicles (UAV) tend to be a popular base for plant-image-collecting platforms. However, detecting corn stands in the field is a challenging task, primarily because of camera motion, leaf fluttering caused by wind, shadows of plants caused by direct sunlight, and the complex soil background. As for the UAV system, there are mainly two limitations for early seedling detection and counting. First, flying height cannot ensure a high resolution for small objects. It is especially difficult to detect early corn seedlings at around one week after planting, because the plants are small and difficult to differentiate from the background. Second, the battery life and payload of UAV systems cannot support long-duration online counting work. In this research project, we developed an automated, robust, and high-throughput method for corn stand counting based on color images extracted from video clips. A pipeline developed based on the YoloV3 network and Kalman filter was used to count corn seedlings online. The results demonstrate that our method is accurate and reliable for stand counting, achieving an accuracy of over 98% at growth stages V2 and V3 (vegetative stages with two and three visible collars) with an average frame rate of 47 frames per second (FPS). This pipeline can also be mounted easily on manned cart, tractor, or field robotic systems for online corn counting.

scholarly journals Development and Performance Evaluation of a Very Low-Cost UAV-Lidar System for Forestry Applications

2020 ◽  
Vol 13 (1) ◽  
pp. 77
Author(s):  
Tianyu Hu ◽  
Xiliang Sun ◽  
Yanjun Su ◽  
Hongcan Guan ◽  
Qianhui Sun ◽  
...  
Keyword(s):  
Forest Inventory ◽  
Low Cost ◽  
Canopy Cover ◽  
Tree Height ◽  
Flying Height ◽  
Tree Level ◽  
Forest Site ◽  
Lidar System ◽  
Individual Tree ◽  
Gap Fraction

Accurate and repeated forest inventory data are critical to understand forest ecosystem processes and manage forest resources. In recent years, unmanned aerial vehicle (UAV)-borne light detection and ranging (lidar) systems have demonstrated effectiveness at deriving forest inventory attributes. However, their high cost has largely prevented them from being used in large-scale forest applications. Here, we developed a very low-cost UAV lidar system that integrates a recently emerged DJI Livox MID40 laser scanner (~$600 USD) and evaluated its capability in estimating both individual tree-level (i.e., tree height) and plot-level forest inventory attributes (i.e., canopy cover, gap fraction, and leaf area index (LAI)). Moreover, a comprehensive comparison was conducted between the developed DJI Livox system and four other UAV lidar systems equipped with high-end laser scanners (i.e., RIEGL VUX-1 UAV, RIEGL miniVUX-1 UAV, HESAI Pandar40, and Velodyne Puck LITE). Using these instruments, we surveyed a coniferous forest site and a broadleaved forest site, with tree densities ranging from 500 trees/ha to 3000 trees/ha, with 52 UAV flights at different flying height and speed combinations. The developed DJI Livox MID40 system effectively captured the upper canopy structure and terrain surface information at both forest sites. The estimated individual tree height was highly correlated with field measurements (coniferous site: R2 = 0.96, root mean squared error/RMSE = 0.59 m; broadleaved site: R2 = 0.70, RMSE = 1.63 m). The plot-level estimates of canopy cover, gap fraction, and LAI corresponded well with those derived from the high-end RIEGL VUX-1 UAV system but tended to have systematic biases in areas with medium to high canopy densities. Overall, the DJI Livox MID40 system performed comparably to the RIEGL miniVUX-1 UAV, HESAI Pandar40, and Velodyne Puck LITE systems in the coniferous site and to the Velodyne Puck LITE system in the broadleaved forest. Despite its apparent weaknesses of limited sensitivity to low-intensity returns and narrow field of view, we believe that the very low-cost system developed by this study can largely broaden the potential use of UAV lidar in forest inventory applications. This study also provides guidance for the selection of the appropriate UAV lidar system and flight specifications for forest research and management.

scholarly journals Operational Study of Drone Spraying Application for the Disinfection of Surfaces against the COVID-19 Pandemic

Drones ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 18
Author(s):  
Higinio González Jorge ◽  
Luis Miguel González de Santos ◽  
Noelia Fariñas Álvarez ◽  
Joaquin Martínez Sánchez ◽  
Fermin Navarro Medina
Keyword(s):  
Dynamic Behavior ◽  
Public Services ◽  
Dynamic Test ◽  
Virus Transmission ◽  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
Flying Height ◽  
Aircraft Systems ◽  
Human Operators ◽  
Lower Height

The COVID-19 pandemic has shown the need to maximize the cleanliness of outside public services and the need to disinfect these areas to reduce the virus transmission. This work evaluates the possibilities of using unmanned aircraft systems for disinfection tasks in these aeras. The operational study focuses on evaluating the static and dynamic behavior, as well as the influence of the flying height, mission speed and flow of spraying. The most recommended height for correct spraying with the drone system under study is 3.0 m. The dynamic test shows that the lower height, 3.0 m, also provides the most adequate spraying footprint, achieving 2.2 m for a speed of 0.5 m/s. The operational behavior is evaluated on three different scenarios, a skatepark with an area around 882.7 m2, an outdoor gym with an area around 545.0 m2 and a multisport court with an area around 2025.7 m2. The cleaning time evaluates the flying duration, battery change and tank refill and results in 41 min for the skatepark (5 tank refills and 2 battery changes), 28.6 min for the outdoor gym (3 tank refills and 2 battery changes) and 96.4 min for the multisport court (11 tank refills and 5 battery changes). Each battery change and each tank refill are estimated to take 4 min each, with a drone autonomy of 7 min. The technology appears competitive compared to other forms of cleaning based, for example, on human operators.

Thermal Strain Imaging of Thermal Flying-Height-Controlled Magnetic Head

2009 ◽  
Vol 2 (12) ◽  
pp. 126504 ◽  
Author(s):  
Keiji Takata ◽  
Noriyasu Ichimei ◽  
Mitsuhiro Okuda
Keyword(s):  
Thermal Strain ◽  
Strain Imaging ◽  
Flying Height ◽  
Magnetic Head ◽  
Thermal Strain Imaging

Performance of Sliders Flying Over Discrete-Track Media

2007 ◽  
Vol 129 (4) ◽  
pp. 712-719 ◽  
Author(s):  
Jianhua Li ◽  
Junguo Xu ◽  
Yuki Shimizu
Keyword(s):  
Estimation Method ◽  
Simulation Method ◽  
Measured Data ◽  
Flying Height ◽  
Height Loss ◽  
Air Bearing ◽  
Slider Air Bearing ◽  
Discrete Track ◽  
Flying Attitude ◽  
Manufacturing Variation

A simulation method in which grooves are virtually distributed on the slider air bearing instead of on the grooved medium surface has been developed and used to investigate the performance of sliders flying over the surface of a discrete-track medium. The simulated flying height loss due to a discrete-track medium coincides well with the measured data, whereas the average-estimation method overestimates flying height loss. Among the characteristics of a slider flying over the surface of a discrete-track medium that were studied are the flying attitude, the effect of groove parameters on flying profile, and the flying height losses due to manufacturing variation and altitude. The results indicate that when a slider is flying over the surface of a discrete-track medium, it will have a higher 3σ of flying height, be more sensitive to altitude, and will have a greater flying height loss.

The Influence of Air-Bearing Surface Geometry on the Dynamics of Sliders

1992 ◽  
Vol 114 (1) ◽  
pp. 26-31 ◽  
Author(s):  
M. Suk ◽  
T. Ishii ◽  
D. Bogy
Keyword(s):  
Surface Defect ◽  
Laser Interferometer ◽  
Low Frequency ◽  
Frequency Component ◽  
Flying Height ◽  
Disk Drives ◽  
Bearing Surface ◽  
Surface Geometry ◽  
Spacing Variation ◽  
Slider Motion

We investigate the influence of crown on slider dynamics during the takeoff stages of disk drives using the multi-channel laser interferometer. We show that a two-dimensional analysis of slider dynamics during takeoff/landing cannot explain all the observed phenomena. We also examine the crown effect on slider motion while it is flying on a thin film disk with a crater-like surface defect. Finally, we measure the spacing variation of the slider as a function of disk speed. It is observed that the initial motion of negative crown sliders during takeoff can be quite similar to positive crown sliders, although the process is quite different. Furthermore, the results suggest that the negative crown sliders may lead to more disk wear due to longer sliding distances. We observed that during steady flying conditions the craterlike surface defect on the disk produced significantly larger motions for negative crown sliders than positive crown sliders. Lastly, we found that both the waveform and magnitude of the low frequency component of the spacing fluctuation is independent of the slider flying height.

Effect of Intermolecular Forces on the Static and Dynamic Performance of Air Bearing Sliders: Part II—Dependence of the Stability on Hamaker Constant, Suspension Preload and Pitch Angle

2005 ◽  
Vol 128 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Vineet Gupta ◽  
David B. Bogy
Keyword(s):  
Pitch Angle ◽  
Dynamic Performance ◽  
Hard Disk Drives ◽  
Intermolecular Forces ◽  
Flying Height ◽  
Total Force ◽  
Air Bearing ◽  
Force Increase ◽  
The Stability ◽  
Fly Height

Intermolecular and surface forces contribute significantly to the total forces acting on air bearing sliders for flying heights below 5 nm. Their contributions to the total force increase sharply with the reduction in flying height, and hence their existence can no longer be ignored in air bearing simulation for hard disk drives. Various experimentally observed dynamic instabilities can be explained by the inclusion of these forces in the model for low flying sliders. In this paper parametric studies are presented using a 3-DOF model to better understand the effect of the Hamaker constants, suspension pre load and pitch angle on the dynamic stability/instability of the sliders. A stiffness matrix is used to characterize the stability in the vertical, pitch, and roll directions. The fly height diagrams are used to examine the multiple equilibriums that exist for low flying heights. It has been found that the system instability increases as the magnitude of the van der Waals force increases. It has also been found that higher suspension pre load and higher pitch angles tend to stabilize the system.

scholarly journals Remotely Sensed Water Limitation in Vegetation: Insights from an Experiment with Unmanned Aerial Vehicles (UAVs)

2019 ◽  
Author(s):  
Kelly Easterday ◽  
Chippie Kislik ◽  
Tod E. Dawson ◽  
Sean Hogan ◽  
Maggi Kelly
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Water Content ◽  
Water Deficit ◽  
Water Status ◽  
Field Measurements ◽  
Flying Height ◽  
Plant Water ◽  
Spectral Indices ◽  
Aerial Vehicles ◽  
The Relationship

Unmanned aerial vehicles (UAVs) equipped with multispectral sensors present an opportunity to monitor vegetation with on-demand high spatial and temporal resolution. In this study, we use multispectral imagery from quadcopter UAVs to monitor the progression of a water manipulation experiment on a common shrub, Baccharis pilularis (coyote brush), at the Blue Oak Ranch Reserve (BORR) near San Jose, California. We recorded multispectral data from the plants at several altitudes with nearly hourly intervals to explore the relationship between two common spectral indices, NDVI and NDRE, and plant water content and water potential, as physiological metrics of plant water status, across a gradient of water deficit. An examination of the spatial and temporal thresholds at which water limitations were most detectable revealed that the best separation between levels of water deficit were at higher resolution (lower flying height), and in the morning (NDVI) and early morning (NDRE). We found that both measures were able to identify moisture deficit in plants and distinguish them from control and watered plants; however, NDVI was better able to distinguish between treatments than NDRE and was more positively correlated with field measurements of plant water content than NDRE. Finally, we explored how relationships between spectral indices and water status changed when the imagery was scaled to courser resolutions provided by satellite-based imagery (PlanetScope) and found that PlanetScope data was able to capture the overall trend in treatments but was not able to capture subtle changes in water content. These kinds of experiments that evaluate the relationship between direct field measurements and UAV camera sensitivity are needed to enable translation of field-based physiology measurements to landscape or regional scales.

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