Developing the Color Full-Scale Schlieren Technique for Flow Visualization

2011 ◽  
Author(s):  
Chien-Chih Chen ◽  
Yu-Cheng Hung ◽  
Shun-Chih Wang ◽  
Chen-Ching Ting
Keyword(s):  
Flow Visualization ◽  
Light Source ◽  
Test Section ◽  
Combustion Process ◽  
High Sensitivity ◽  
Full Scale ◽  
Large Area ◽  
Fuel Gas ◽  
Schlieren Technique ◽  
Color Mask

The full-scale schlieren technique was famous and especially developed for flow visualization with large area of test section. This article further presents the color full-scale schlieren technique which captures more colorful images and also promotes the resolution of images. In this work, the developed color full-scale schlieren technique used the light source which penetrates through the linear grating color mask with alternated red, green, and blue colors. The applied light source is made of flat plate and with modular structure which is convenient for varying area of the light source. The width of the grating color lines is 6 mm. The applied area of light source and its test section are 2×2 and 1×1 m2 respectively. In future, this developed color full-scale schlieren technique will be further used for e.g. CO flow visualization during incomplete combustion process of fuel gas. The results in this work show beautiful images and also with expected high sensitivity.

Developing the Modular Background-Oriented Full-Scale Schlieren Technique

2011 ◽  
Author(s):  
Yu-Cheng Hung ◽  
Chien-Chih Chen ◽  
Shun-Chih Wang ◽  
Chen-Ching Ting
Keyword(s):  
Light Source ◽  
Full Scale ◽  
Schlieren Technique ◽  
Fluorescent Lamps

This article mainly presents the full-scale schlieren technique using modular background-oriented light source instead of the retroreflective method. Moveover, this article is also focused on investigating sensitivity influence of the cutoff light percentage by the cutoff grid. An unit background-oriented light source is composed of the fluorescent lamps of Philips-865, the atomizing film, and the linear grating mask in this work. The applied cutoff grids are with 50, 60, 70, 80, and 90% of the cutoff light percentage respectively. The results show that a cutoff grid with 90% cutoff light for the conventional Z-arrangement schlieren technique and a cutoff grid with 60% cutoff light for the full-scale schlieren technique receives the best visualization.

Limitations of the Schlieren technique for shielding gas flow visualization in arc welding processes

2021 ◽  
Author(s):  
Mateus Barancelli Schwedersky ◽  
Álisson Fernandes da Rosa ◽  
Marcelo Pompermaier Okuyama ◽  
Régis Henrique Gonçalves e Silva
Keyword(s):  
Flow Visualization ◽  
Arc Welding ◽  
Gas Flow ◽  
Shielding Gas ◽  
Schlieren Technique ◽  
Welding Processes

scholarly journals Design of a Sensitive Balloon Sensor for Safe Human–Robot Interaction

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2163
Author(s):  
Dongjin Kim ◽  
Seungyong Han ◽  
Taewi Kim ◽  
Changhwan Kim ◽  
Doohoe Lee ◽  
...  
Keyword(s):  
High Performance ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Human Robot Interaction ◽  
Large Area ◽  
Tactile Sensors ◽  
Robot Interaction ◽  
Mechanical Crack ◽  
Flexible Strain Sensor ◽  
Contact Sensing

As the safety of a human body is the main priority while interacting with robots, the field of tactile sensors has expanded for acquiring tactile information and ensuring safe human–robot interaction (HRI). Existing lightweight and thin tactile sensors exhibit high performance in detecting their surroundings. However, unexpected collisions caused by malfunctions or sudden external collisions can still cause injuries to rigid robots with thin tactile sensors. In this study, we present a sensitive balloon sensor for contact sensing and alleviating physical collisions over a large area of rigid robots. The balloon sensor is a pressure sensor composed of an inflatable body of low-density polyethylene (LDPE), and a highly sensitive and flexible strain sensor laminated onto it. The mechanical crack-based strain sensor with high sensitivity enables the detection of extremely small changes in the strain of the balloon. Adjusting the geometric parameters of the balloon allows for a large and easily customizable sensing area. The weight of the balloon sensor was approximately 2 g. The sensor is employed with a servo motor and detects a finger or a sheet of rolled paper gently touching it, without being damaged.

scholarly journals Effects of Crystal Morphology on the Hot-Carrier Dynamics in Mixed-Cation Hybrid Lead Halide Perovskites

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 708
Author(s):  
Daniele Catone ◽  
Giuseppe Ammirati ◽  
Patrick O’Keeffe ◽  
Faustino Martelli ◽  
Lorenzo Di Mario ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Carrier Dynamics ◽  
Large Area ◽  
Photovoltaic Properties ◽  
Time Resolved ◽  
Hot Carrier ◽  
Mixed Cation ◽  
Small Crystals ◽  
Characterization Of Materials ◽  
Lead Halide

Ultrafast pump-probe spectroscopies have proved to be an important tool for the investigation of charge carriers dynamics in perovskite materials providing crucial information on the dynamics of the excited carriers, and fundamental in the development of new devices with tailored photovoltaic properties. Fast transient absorbance spectroscopy on mixed-cation hybrid lead halide perovskite samples was used to investigate how the dimensions and the morphology of the perovskite crystals embedded in the capping (large crystals) and mesoporous (small crystals) layers affect the hot-carrier dynamics in the first hundreds of femtoseconds as a function of the excitation energy. The comparative study between samples with perovskite deposited on substrates with and without the mesoporous layer has shown how the small crystals preserve the temperature of the carriers for a longer period after the excitation than the large crystals. This study showed how the high sensitivity of the time-resolved spectroscopies in discriminating the transient response due to the different morphology of the crystals embedded in the layers of the same sample can be applied in the general characterization of materials to be used in solar cell devices and large area modules, providing further and valuable information for the optimization and enhancement of stability and efficiency in the power conversion of new perovskite-based devices.

scholarly journals A Miniature Optical Force Dual-Axis Accelerometer Based on Laser Diodes and Small Particles Cavities

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1375
Author(s):  
Junji Pu ◽  
Kai Zeng ◽  
Yulie Wu ◽  
Dingbang Xiao
Keyword(s):  
Light Source ◽  
Optical System ◽  
High Sensitivity ◽  
Measurement Range ◽  
Optical Force ◽  
Zero Bias ◽  
Micro Electro Mechanical Systems ◽  
Force Effect ◽  
High Measurement ◽  
Mems Technology

In recent years, the optical accelerometer based on the optical trapping force effect has gradually attracted the attention of researchers for its high sensitivity and high measurement accuracy. However, due to its large size and the complexity of optical path adjustment, the optical force accelerometers reported are only suitable for the laboratory environment up to now. In this paper, a miniature optical force dual-axis accelerometer based on the miniature optical system and a particles cavity which is prepared by Micro-Electro-Mechanical Systems (MEMS) technology is proposed. The overall system of the miniature optical levitation including the miniature optical system and MEMS particles cavity is a cylindrical structure with a diameter of about 10 mm and a height of 33 mm (Φ 10 mm × 33 mm). Moreover, the size of this accelerometer is 200 mm × 100 mm × 100 mm. Due to the selected light source being a laser diode light source with elliptical distribution, it is sensitive to the external acceleration in both the long axis and the short axis. This accelerometer achieves a measurement range of ±0.17 g–±0.26 g and measurement resolution of 0.49 mg and 1.88 mg. The result shows that the short-term zero-bias stability of the two orthogonal axes of the optical force accelerometer is 4.4 mg and 9.2 mg, respectively. The main conclusion that can be drawn is that this optical force accelerometer could provide an effective solution for measuring acceleration with an optical force effect for compact engineering devices.

Si Photonics Deployment Using Cu Pillar Interconnect and Chip On Wafer Platform

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 001663-001681
Author(s):  
Miguel Jimarez
Keyword(s):  
Light Source ◽  
Silicon Photonics ◽  
High Speed ◽  
High Sensitivity ◽  
Optical Path ◽  
Clock Recovery ◽  
Wafer Scale ◽  
Si Photonics ◽  
Cu Pillar ◽  
Fine Pitch

We introduce a high-speed 4x25Gbps, MSA-compliant, QSFP transceiver built on a Silicon Photonics platform. The transceiver integrates high sensitivity receivers, CTLE, clock recovery, modulator drivers and BIST on a TSMC 28nm die connected to the photonic die thru a fine pitch (50um) Copper Pillar interface. A wafer-scale approach, Chip on Wafer, CoW, is used to assemble the electronic die and the light source on to the photonic die, so that the full optical path can be tested, at speed, in loopback configuration in wafer form, using a standard ATE solution. This presentation focuses on the CoW assembly development aspects of the transceiver. Wafer probe and bump, die processing services, CoW assembly and Back End of Line, BEOL, Test Services will be presented.

scholarly journals High-Sensitivity Large-Area Photodiode Read-Out Using a Divide-and-Conquer Technique

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6316
Author(s):  
Guillermo Royo ◽  
Carlos Sánchez-Azqueta ◽  
Concepción Aldea ◽  
Santiago Celma
Keyword(s):  
Traditional Approach ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Divide And Conquer ◽  
Transimpedance Amplifier ◽  
Large Area ◽  
Signal To Noise ◽  
Remarkable Improvement ◽  
The Core ◽  
Novel Technique

In this letter, we present a novel technique to increase the sensitivity of optical read-out with large integrated photodiodes (PD). It consists of manufacturing the PD in several pieces, instead of a single device, and connecting a dedicated transimpedance amplifier (TIA) to each of these pieces. The output signals of the TIAs are combined, achieving a higher signal-to-noise ratio than with the traditional approach. This work shows a remarkable improvement in the sensitivity and transimpedance without the need for additional modifications or compensation techniques. As a result, an increase in sensitivity of 7.9 dBm and transimpedance of 8.7 dBΩ for the same bandwidth is achieved when dividing the photodiode read-out into 16 parallel paths. The proposed divide-and-conquer technique can be applied to any TIA design, and it is also independent of the core amplifier structure and fabrication process, which means it is compatible with every technology allowing the integration of PDs.

Full-Scale Evaluation of Relatively Thin Airfield Pavements

2020 ◽  
Vol 2674 (10) ◽  
pp. 658-669
Author(s):  
W. Jeremy Robinson ◽  
Jeb S. Tingle ◽  
Carlos R. Gonzalez
Keyword(s):  
Asphalt Concrete ◽  
Test Section ◽  
Concrete Surface ◽  
Full Scale ◽  
Test Items ◽  
Pavement Structures ◽  
Base Course ◽  
And Performance ◽  
Rutting Behavior ◽  
Aggregate Base

A full-scale airfield pavement test section was constructed and trafficked by the U.S. Army Engineer Research and Development Center (ERDC) to evaluate the performance of relatively thin airfield pavement structures. The test section consisted of four test items that included three asphalt pavement thicknesses and two different aggregate base courses. The test items were subjected to simulated aircraft traffic to evaluate their response and performance to realistic aircraft loads. Rutting behavior, instrumentation response, and falling weight deflectometer response were monitored at selected traffic intervals. It was found that the performance of the airfield pavement sections were most sensitive to aggregate base course properties, where a 50% reduction in base course strength resulted in a 99% reduction in allowable passes. The data suggested that when sufficient asphalt thickness is not provided, the failure mechanism shifted from subgrade failure to base course failure, particularly at higher subgrade CBR values. In addition, the number of aircraft passes sustained was less than that predicted by current Department of Defense (DOD) methods that include assumptions of a high-quality aggregate base and a minimum asphalt concrete thickness. The results of this study were used to extend existing DOD pavement design and evaluation techniques to include the evaluation of airfield pavement sections that do not meet the current criteria for aggregate base quality and minimum asphalt concrete surface thickness. These performance data were used to develop a new base failure design curve using existing stress-based design criteria.

scholarly journals Locally Controlled Sensing Properties of Stretchable Pressure Sensors Enabled by Micro-Patterned Piezoresistive Device Architecture

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6588
Author(s):  
Jun Ho Lee ◽  
Jae Sang Heo ◽  
Keon Woo Lee ◽  
Jae Cheol Shin ◽  
Jeong-Wan Jo ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Silver Nanowires ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Fast Response ◽  
Large Area ◽  
Site Specific ◽  
Sensing Properties ◽  
Sensing Range ◽  
Wide Range

For wearable health monitoring systems and soft robotics, stretchable/flexible pressure sensors have continuously drawn attention owing to a wide range of potential applications such as the detection of human physiological and activity signals, and electronic skin (e-skin). Here, we demonstrated a highly stretchable pressure sensor using silver nanowires (AgNWs) and photo-patternable polyurethane acrylate (PUA). In particular, the characteristics of the pressure sensors could be moderately controlled through a micro-patterned hole structure in the PUA spacer and size-designs of the patterned hole area. With the structural-tuning strategies, adequate control of the site-specific sensitivity in the range of 47~83 kPa−1 and in the sensing range from 0.1 to 20 kPa was achieved. Moreover, stacked AgNW/PUA/AgNW (APA) structural designed pressure sensors with mixed hole sizes of 10/200 µm and spacer thickness of 800 µm exhibited high sensitivity (~171.5 kPa−1) in the pressure sensing range of 0~20 kPa, fast response (100~110 ms), and high stretchability (40%). From the results, we envision that the effective structural-tuning strategy capable of controlling the sensing properties of the APA pressure sensor would be employed in a large-area stretchable pressure sensor system, which needs site-specific sensing properties, providing monolithic implementation by simply arranging appropriate micro-patterned hole architectures.

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