A wireless, in‐situ ultrasonic guided wave structural health monitoring (SHM) system was developed and tested for aircraft wing inspection. It applies small, low cost and light weight piezoelectric (PZT) disc transdu...
A wireless, in‐situ ultrasonic guided wave structural health monitoring (SHM) system was developed and tested for aircraft wing inspection. It applies small, low cost and light weight piezoelectric (PZT) disc transducer network bonded to the surface of a structure, and an embedded miniature diagnosis device that can generate 350 kHz, 70 V peak‐to‐peak tone‐burst signal; collect, amplify and digitize multiple channel ultrasonic signals; and process the data on‐board and transfer them wirelessly to a ground station. The whole system could be powered by an X‐band microwave rectenna that converts illuminating microwave energy into DC. The data collected with this device are almost identical with those collected through a direct‐wire connection.
Current non‐destructive techniques for defect analysis of FRP bridge decks have a narrow scope. These techniques are very good at detecting certain types of defects but are not robust enough to detect all defects by ...
Current non‐destructive techniques for defect analysis of FRP bridge decks have a narrow scope. These techniques are very good at detecting certain types of defects but are not robust enough to detect all defects by themselves. For example, infrared thermography (IRT) can detect air filled defects and Ground Penetrating Radar (GPR) is good at detecting water filled ones. These technologies can be combined to create a more robust defect detection scheme. To accomplish this, an Unmanned Ground Vehicle (UGV) has been designed that incorporates both IR and GPR analysis to create a comprehensive defect map of a bridge deck. The UGV autonomously surveys the deck surface and acquires data. The UGV has two 1.5 GHz ground coupled GPR antennas that are mounted on the front of the UGV to collect GPR data. It also incorporates an active heating source and a radiometric IR camera to capture IR images of the deck, even in less than ideal weather scenarios such as cold cloudy days. The UGV is designed so that it can collect data in an assembly line fashion. It moves in 1 foot increments. When moving, it collects GPR data from the two antennas. When it stops it heats a section of the deck. The next time it stops to heat a section, the IR camera is analyzing the preheated deck section while preparing for the next section. Because the data is being continually collected using this method, the UGV can survey the entire deck in an efficient and timely manner.
Infrared (IR) Thermography is a good way of detecting air filled defects in FRP decks. When heat is applied to the deck surface, the material over the air void heats up faster and becomes hotter than the surrounding a...
Infrared (IR) Thermography is a good way of detecting air filled defects in FRP decks. When heat is applied to the deck surface, the material over the air void heats up faster and becomes hotter than the surrounding area and an IR camera can distinguish this defective area from a sound area in the deck based on surface temperature measurements. Since this technique requires application of heat in order to produce results, it seems only logical that one should research the effects of different heating types on the defect analysis. For this study, various heat sources; such as the sun, a 5000 BTU quartz electric heater, a 9000 BTU propane convection heater, and a 35000 BTU forced air propane heater, were used to heat up an FRP deck specimen with built‐in defects for IR analysis. Different heating times were used to determine the effects on the accuracy and the total elapsed time involved in seeing a defect in the resultant IR images. A few methods, such as CO2 cooling, for decreasing the time it takes to see the defect in the image were also explored.
Active thermography is an established NDE technique that has become the method of choice in many industrial applications which require non‐contact access to the parts under test. Unfortunately, when conducting on‐li...
Active thermography is an established NDE technique that has become the method of choice in many industrial applications which require non‐contact access to the parts under test. Unfortunately, when conducting on‐line infrared (IR) inspection of powder metallic compacts, complications can arise due the generally low emissivity of metals and the thermally noisy environment typically encountered in manufacturing plants. In this paper we present results of an investigation that explores the suitability of active IR imaging of powder metallurgy compacts for the detection of surface and sub‐surface defects in the pre‐sinter state and in an on‐line manufacturing setting to ensure complete quality assurance. Additional off‐line tests can be carried out for statistical quality analyses. In this research, the IR imaging of sub‐surface defects is based on a transient instrumentation approach that relies on an electric control system which synchronizes and monitors the thermal response due to an electrically generated heat source. Preliminary testing reveals that this newly developed pulsed thermography system can be employed for the detection of subsurface defects in green‐state parts. Practical measurements agree well with theoretical predictions. The inspection approach being developed can be used for the testing of green‐state compacts as they exit the compaction press at speeds of up to 1,000 parts per hour.
There are some fatigue damage estimation methods of the austenitic stainless steel that uses the martensitic transformation. For instance, they are the remanent magnetization method, the excitation method, and so on. ...
There are some fatigue damage estimation methods of the austenitic stainless steel that uses the martensitic transformation. For instance, they are the remanent magnetization method, the excitation method, and so on. Those two methods are being researched also in our laboratory now. In the remanent magnetization method, it is well known that the relation between fatigue damage and the remanent magnetization is simple, clear, and reproducible. However, this method has the disadvantage to need a special magnetizer. This method cannot be easily used on the site such as the factory. On the other hand, because the special magnetizer is unnecessary, the excitation method can use easily on the site. The output signal of this method is small. In this paper, two fatigue evaluation methods such as the remanent magnetization method and the excitation method are introduced. In addition, we report on the result of comparing the fatigue evaluation performances of two methods.
We report fabrication and characterization of lambda DNA field effect transistors. Our transistor is basically a DNA network formed in between the source and the drain electrode on a SiO2/Si substrate. Measured source...
We report fabrication and characterization of lambda DNA field effect transistors. Our transistor is basically a DNA network formed in between the source and the drain electrode on a SiO2/Si substrate. Measured source‐drain current (ISD) as a function of the source‐drain bias shows nonlinear characteristics. Such non‐linearity is typically a manifestation of the semiconducting behavior and is believed to be caused by the energy gap of the DNA molecules. Our sample shows a field effect behavior and we observe that ISD increases as the gate bias becomes more negative. It suggests that the lambda DNA used in our experiment is a p‐type molecule.
Planning of HIFU therapy using patient‐specific data is crucial for successful results. We are developing integrated tools for HIFU therapy planning using pre‐treatment imaging, HIFU simulation, and interactive visu...
Planning of HIFU therapy using patient‐specific data is crucial for successful results. We are developing integrated tools for HIFU therapy planning using pre‐treatment imaging, HIFU simulation, and interactive visualization. We employ techniques for 2D/3D image segmentation to generate layered surface model; ultrasound simulation of beam intensity distribution and HIFU temperature profiles; visualization of integrated 3D anatomy and US beam simulation; and interactive strategy planning for studying the approaches of HIFU delivery. We present a systematic approach for developing and integrating these tools in interactive software using C++, OpenGL, C♯.Net, and ITK. With interactive visualization of the HIFU simulation parameters and the tissue effects, a range of scenario could be studied for an optimal HIFU delivery for a given patient. This continuing work has potential to aid development of optimized high‐precision HIFU dosimetry and patient‐specific planning strategies by reducing the guess work on dosage parameters and thereby reducing the overall treatment duration and reduced exposure to non‐target tissues.
This paper presents a LiGA (German acronym for LIthografie, Galvanoformung, Abformung) based micro biopsy actuator for the capsular endoscope. The proposed fabricated actuator aims to extract sample tissues inside sma...
This paper presents a LiGA (German acronym for LIthografie, Galvanoformung, Abformung) based micro biopsy actuator for the capsular endoscope. The proposed fabricated actuator aims to extract sample tissues inside small gastric intestines, that cannot be reached by conventional biopsy. The actuator size is 10 mm in diameter and 1.8 mm in length. The mechanism is of a slider‐crank type. The actuator consists of trigger, rotational module, and micro biopsy tool. The core components are fabricated using the LiGA process, for overcoming the limitations in accuracy of conventional precision machining.
Critical aircraft structures are susceptible to hidden corrosion. Find‐it and fix‐it approaches are inefficient as it relates to managing the problems associated with corrosion. More comprehensive corrosion informat...
Critical aircraft structures are susceptible to hidden corrosion. Find‐it and fix‐it approaches are inefficient as it relates to managing the problems associated with corrosion. More comprehensive corrosion information may be obtained using data fusion from several detection and evaluation methods. To this end, microwave, conventional and pulsed eddy current data from a multi‐layer corroded panel, representing an aircraft lap joint, are fused and used as inputs to a structural analysis model to obtain a comprehensive snapshot of the corroded environment. This paper presents the data fusion algorithm and the structural analysis model along with a discussion of the results.
Understanding the effect of overlaying tissues on HIFU lesion is crucial for estimating HIFU dose distribution at a target tissue. We have run a series of experiments to systematically observe the effects of the overl...
Understanding the effect of overlaying tissues on HIFU lesion is crucial for estimating HIFU dose distribution at a target tissue. We have run a series of experiments to systematically observe the effects of the overlaying tissues on the HIFU beam and ultimately the lesion created in the target tissue. First, we mapped out the HIFU transducer beam (in low power) under water without and with different overlaying tissue layers. Then, we performed a series of experiments in high power to create lesions in target tissues (e.g., liver) without and with overlaying tissues (e.g. muscle). The lesions are characterized by slicing the tissues and reconstructing the 3D lesion from calibrated pictures of the target tissue slices. The low power beam measurements show significant effects in terms of severe beam wave‐field amplitude distortion due to phase aberration introduced by velocity inhomogeneity in the overlaying tissues. These results compare well qualitatively with the computational models. The results from the high power HIFU lesions in a similar setup using various tissues, including liver and muscle, provide understanding of the significance of phase aberration in overlaying tissues and could prove useful towards high precision HIFU therapy.
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