Computational and Experimental Approach to Understanding Legged Mobility in Micro Ground Vehicles

2014 ◽  
Author(s):  
Rudranarayan Mukherjee ◽  
Scott Moreland ◽  
Isaac Kim ◽  
Nikhil Lele ◽  
Stephen Goodwin ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Granular Media ◽  
Necessary Condition ◽  
High Fidelity ◽  
Natural Environments ◽  
Ground Vehicles ◽  
Tactile Sensors ◽  
High Speed Imaging ◽  
Vehicle Mobility

The army has a vision for using autonomous micro ground vehicles (MGV) for soldier support in the last 100 meters of operations in urban and natural environments. These MGVs are expected to typically fit in a human palm and weigh in the order of 30–50 grams. Robust mobility is a necessary condition to ensure operations. Given the severe challenge of size, weight and power (SWAP) of the MGVs, significant uncertainties currently remain in quantifying micro ground vehicle mobility. In this paper we describe a research methodology and representative results for understanding legged MGV mobility in different types of terrain. Our methodology is based on a synergy of novel experimental setup and high-fidelity computational methods. We report the use of a novel “single-leg” test rig that uses tactile sensors to measure ground interaction loads. We also report the use of high speed imaging and use of particle image velocimetry to understand soil deformation during legged interactions with terrain. Finally, we report on the use of multibody dynamics and High Performance Computing (HPC) based granular media simulations. This conference paper emphases more on the overall approach based on synergistic use of high fidelity modeling and experimental methods supported by representative results rather than presenting a detailed analyses of the results.

scholarly journals Experimental study of the dynamic behaviour of High Performance Concrete (HPC) under tensile loading

2018 ◽  
Vol 183 ◽  
pp. 02043 ◽  
Author(s):  
Bratislav Lukić ◽  
Dominique Saletti ◽  
Pascal Forquin
Keyword(s):  
High Speed ◽  
High Performance ◽  
High Performance Concrete ◽  
Imaging System ◽  
Spall Strength ◽  
High Speed Imaging ◽  
Dynamic Tensile Strength ◽  
Full Field ◽  
Local Point ◽  
Measurement Results

This paper presents the measurement results of the dynamic tensile strength of a High Performance Concrete (HPC) obtained using full-field identification method. An ultra-high speed imaging system and the virtual fields method were used to obtain this information. Furthermore the measurement results were compared with the local point-wise measurement to validate the data pressing. The obtained spall strength was found to be consistently 20% lower than the one obtained when the Novikov formula is used.

scholarly journals A portable smartphone-based laryngoscope system for high-speed vocal cord imaging of patients with throat disorders (Preprint)

2020 ◽  
Author(s):  
Jun Ki Kim ◽  
Youngkyu Kim ◽  
Jungmin Oh ◽  
Seung-Ho Choi ◽  
Ahra Jung ◽  
...  
Keyword(s):  
Image Processing ◽  
Vocal Cord ◽  
High Speed ◽  
High Performance ◽  
Vocal Folds ◽  
Frame Rate ◽  
Endoscopic Imaging ◽  
High Speed Imaging ◽  
Underdeveloped Countries ◽  
Longitudinal Edge

BACKGROUND Recently, high-speed digital imaging (HSDI), especially HSD endoscopic imaging is being routinely used for the diagnosis of vocal fold disorders. However, high-speed digital endoscopic imaging devices are usually large and costly, which limits access by patients in underdeveloped countries and in regions with inadequate medical infrastructure. Modern smartphones have sufficient functionality to process the complex calculations that are required for processing high-resolution images and videos with a high frame rate. Recently, several attempts have been made to integrate medical endoscopes with smartphones to make them more accessible to underdeveloped countries. OBJECTIVE To develop a smartphone adaptor for endoscopes to reduce the cost of devices, and to demonstrate the possibility of high-speed vocal cord imaging using the high-speed imaging functions of a high-performance smartphone camera. METHODS A customized smartphone adaptor was designed for clinical endoscopy using selective laser melting (SLM)-based 3D printing. Existing laryngoscope was attached to the smartphone adaptor to acquire high-speed vocal cord endoscopic images. Only existing basic functions of the smartphone camera were used for HSDI of the vocal folds. For image processing, segmented glottal areas were calculated from whole HSDI frames, and characteristics such as volume, shape and longitudinal edge length were analyzed. RESULTS High-speed digital smartphone imaging with the smartphone-endoscope adaptor could achieve 940 frames per second, and was used to image the vocal folds of five volunteers. The image processing and analytics demonstrated successful calculation of relevant diagnostic variables from the acquired images. CONCLUSIONS A smartphone-based HSDI endoscope system can function as a point-of-care clinical diagnostic device. Furthermore, this system is suitable for use as an accessible diagnostic method in underdeveloped areas with inadequate medical service infrastructure.

scholarly journals Mechanical models of sandfish locomotion reveal principles of high performance subsurface sand-swimming

2011 ◽  
Vol 8 (62) ◽  
pp. 1332-1345 ◽  
Author(s):  
Ryan D. Maladen ◽  
Yang Ding ◽  
Paul B. Umbanhowar ◽  
Adam Kamor ◽  
Daniel I. Goldman
Keyword(s):  
High Speed ◽  
High Performance ◽  
Granular Media ◽  
The Body ◽  
Physical Models ◽  
Particle Simulation ◽  
Sinusoidal Wave ◽  
Drag Forces ◽  
Single Period ◽  
Discrete Particle Simulation

We integrate biological experiment, empirical theory, numerical simulation and a physical model to reveal principles of undulatory locomotion in granular media. High-speed X-ray imaging of the sandfish lizard, Scincus scincus , in 3 mm glass particles shows that it swims within the medium without using its limbs by propagating a single-period travelling sinusoidal wave down its body, resulting in a wave efficiency, η , the ratio of its average forward speed to the wave speed, of approximately 0.5. A resistive force theory (RFT) that balances granular thrust and drag forces along the body predicts η close to the observed value. We test this prediction against two other more detailed modelling approaches: a numerical model of the sandfish coupled to a discrete particle simulation of the granular medium, and an undulatory robot that swims within granular media. Using these models and analytical solutions of the RFT, we vary the ratio of undulation amplitude to wavelength ( A / λ ) and demonstrate an optimal condition for sand-swimming, which for a given A results from the competition between η and λ . The RFT, in agreement with the simulated and physical models, predicts that for a single-period sinusoidal wave, maximal speed occurs for A / λ ≈ 0.2, the same kinematics used by the sandfish.

scholarly journals Improved evaluation of granular media flows using an X-ray scanning compatible cone-plate setup

2021 ◽  
Vol 249 ◽  
pp. 03020
Author(s):  
Zohreh Farmani ◽  
Jing Wang ◽  
Ralf Stannarius ◽  
Martina Bieberle ◽  
Frank Barthel ◽  
...  
Keyword(s):  
Granular Materials ◽  
High Speed ◽  
Granular Media ◽  
Flow Behavior ◽  
Three Dimensional ◽  
High Speed Imaging ◽  
Flow Measurements ◽  
Flow Rates ◽  
X Ray ◽  
Wide Range

To understand the typically heterogeneous flowing behavior of granular materials, it is important to combine flow tests with three-dimensional imaging. To probe the flow behavior of granular materials over a wide range of flow rates, it is imperative to be able to impose such flow rates in a well controlled manner while performing imaging tests that are compatible with all imposed flow rates. Achieving both flow control and bulk imaging capacity is challenging for a number of reasons. Here, we describe the design of a setup in which we are able to do imaging while imposing a constant overall shear rate on a granular material. We characterize the setup in which flow tests will be performed, which consists of a bottom-driven cone-plate or double-cone design. We show that the setup can be integrated in x-ray microtomography devices to aid particle tracking based flow measurements. The design is also compatible with typical rheometer setups. We also perform high speed imaging of a granular flow in an ultra-fast x-ray scanner, for which we provide proof-of-principle data in a simplified shear setup. The designed flow geometry is also compatible with said high speed imaging facility, where particle image velocimetry can be employed to extract quantitative flow field data.

Evaporative Wicking Phenomena on Nanotextured Surfaces for Heat Pipe Applications

2018 ◽  
Author(s):  
Duong Vy Le ◽  
Shiwei Zhang ◽  
Jonggyu Lee ◽  
Yoonjin Won
Keyword(s):  
Thin Film ◽  
High Speed ◽  
High Performance ◽  
Heat Dissipation ◽  
Thermal Conditions ◽  
Temperature Profiles ◽  
Textured Surfaces ◽  
High Speed Imaging ◽  
Thin Film Evaporation ◽  
Film Evaporation

Thermal management has become more important as high-performance electronics have concentrated heat loads with current cooling technologies. This motivates the implementation of new cooling solutions to dissipate high heat levels from high-performance electronics. Evaporative cooling is one of the most promising approaches for meeting these future thermal demands. Thin-film evaporation promotes heat dissipation through the phase change process with minimal conduction resistance. In this process, it is important to design surface properties and structures that can minimize meniscus thickness, increase liquid-vapor interface area, and enhance evaporation performances. In this study, we thereby investigate thin-film evaporation by employing nanotextured copper substrates for varying thermal conditions. Specifically, we visualize the liquid spreading on the nanotextured surfaces using a high-speed imaging technique to quantify evaporative heat transfer for various designs. The permeability is calculated using an enhanced wicking model to account for the evaporation effect. The mass balance measurements allow us to calculate evaporation rates. Then, we employ infrared thermography to examine two-dimensional temporal temperature profiles of the samples during the evaporative wicking with a given heat flux. The combination of time-lapse images, evaporation rate measurements, and temperature profiles will provide a comprehensive understanding of evaporation performances of textured surfaces.

scholarly journals Investigation of the sintering kinetic and development of ceramic masses for obtaining large-format porcelain stoneware in the conditions of high-speed firing

2020 ◽  
Vol 120 ◽  
pp. 160-174
Author(s):  
O. Yu. Fedorenko ◽  
M. I. Ryshchenko ◽  
S. V. Kartyshev ◽  
L. O. Yashchenko ◽  
O. Ya. Pitak
Keyword(s):  
Energy Saving ◽  
High Speed ◽  
High Performance ◽  
Structural Phase ◽  
International Standards ◽  
Necessary Condition ◽  
Large Format ◽  
Waste Products ◽  
Wide Range ◽  
Acicular Mullite

The paper considers the resource and energy saving reserves in the production of large-format stoneware slabs. The possibility of replacing high-quality feldspars with materials of technogenic origin, such as the extraction and processing waste of various feldspar-bearing rocks of domestic deposits has been investigated. The possibility of sintering process intensification has been investigated, as a condition for the use of high-speed firing modes in the stoneware production. As a result of the carried out studies, the kinetic features of ceramic masses sintering with alkaline syenites, granites and pegmatite enrichment wastes as fluxing component were determined. The formation conditions of densely sintered materials with a complex of high operational properties have been determined. The expediency of replacing Turkish feldspars with waste products of alkaline syenites has been established, while the level of physical, mechanical and operational properties of stoneware slabs meets the requirements of international standards. It is shown that, the use of complex flux, including feldspar-bearing rocks waste and dolomite, provides a significant decrease in the firing temperature of products (up to 1150 °C) while maintaining a high level of properties of stoneware slabs of class BІa. The obtained data indicate the possibility of optimizing the heat treatment parameters from the view point of energy saving with the further use of alternative fluxes in the large-format stoneware production. On the example of using the alkaline syenites wastes, the optimal ratios of the clay and fluxing components of ceramic masses have been established to obtain products with a complex of high performance characteristics when burning white clays of different chemical and mineral composition, which is a necessary condition for using a wide range of decorating techniques stoneware slabs. The structural-phase features of materials obtained under the conditions of high-speed firing are established: the formation of finely dispersed acicular mullite, which plays the role of a reinforcing component, as well as high structural homogeneity and maximum compaction, as evidenced by a few individual small pores presence. The combination of excellent technical qualities and large dimensions opens up new possibilities for the use of stoneware slabs as structural elements (countertops, ventilated facades, insulating panels for the installation of electrical systems, etc.).

Evaporative Wicking Phenomena on Nanotextured Surfaces

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Duong Vy Le ◽  
Quang N. Pham ◽  
Jonggyu Lee ◽  
Shiwei Zhang ◽  
Yoonjin Won
Keyword(s):  
Thin Film ◽  
High Speed ◽  
High Performance ◽  
Heat Dissipation ◽  
Thermal Conditions ◽  
Temperature Profiles ◽  
Textured Surfaces ◽  
High Speed Imaging ◽  
Thin Film Evaporation ◽  
Film Evaporation

AbstractAs modern electronics become miniaturized with high power, thermal management for electronics devices has become significant. This motivates the implementation of new cooling solutions to dissipate high-heat levels from high-performance electronics. Evaporative cooling is one of the most promising approaches for meeting these future thermal demands. Thin-film evaporation promotes heat dissipation through the phase change process with minimal conduction resistance. In this process, it is important to design surface structures and corresponding surface properties that can minimize meniscus thickness, increase liquid–vapor interfacial area, and enhance evaporation performances. In this study, we investigate thin-film evaporation by employing nanotextured copper substrates for varying thermal conditions. The liquid spreading on the nanotextured surfaces is visualized using a high-speed imaging technique to quantify evaporative heat transfer for various surfaces. The permeability is calculated using an enhanced wicking model to estimate the evaporation effect combined with the mass measurements. Then, infrared (IR) thermography is employed to examine two-dimensional temporal temperature profiles of the samples during the evaporative wicking with a given heat flux. The combination of optical time-lapse images, evaporation rate measurements, and temperature profiles will provide a comprehensive understanding of evaporation performances using textured surfaces.

Cooling of High-Performance Server Modules Using Direct Immersion

2012 ◽  
Author(s):  
Aravind Sridhar ◽  
Sarah Styslinger ◽  
Christopher Duron ◽  
Sushil H. Bhavnani ◽  
Roy W. Knight ◽  
...  
Keyword(s):  
Heat Flux ◽  
High Speed ◽  
High Performance ◽  
Heat Dissipation ◽  
Heat Removal ◽  
Liquid Pool ◽  
Circuit Board ◽  
Air Cooling ◽  
High Speed Imaging ◽  
Close Proximity

An alternative to air-cooling of high performance computing equipment is presented. Heat removal via pool boiling in FC-72 was tested. Tests were conducted on a multichip module using 1.8 cm × 1.8 cm test die with multiple thermal test cells with temperature sensing capability. Measurements with the bare silicon die in direct contact with the fluid are reported. Additional testing included the test die directly indium-attached to copper heat spreaders having surface treatments. A screen-printed sintered boiling-enhanced surface (4 cm × 4 cm) was evaluated. Tests were conducted on an array of five die. Parameters tested include heat flux levels, dielectric liquid pool conditions (saturated or subcooled), and effect of neighboring die. Information was gathered on surface temperatures for a range of heat flux values up to 12 W/cm2. The highest heat dissipated from a circuit board with five bare die was 195 W (39 W per die). Addition of the heat spreader allowed heat dissipation of up to 740 W (from a five-die array). High-speed imaging was also acquired to help examine detailed information on the boiling process. Numerical modeling indicated that placing multiple boards in close proximity to each other did not degrade performance until board spacing was reduced to 3 mm.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

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