Guided tracing: Our algorithm reduces propagation cost by dynamically tracing fewer rays and decreasing receiver size while maintaining accuracy. Thanks to Gamebryo for providing an academic license for their development kit, Marko Dabrovic for his excellent models, and Nicolas Tsingos for his comments on early versions of this work. Of all the applications of industrial ultrasonic testing, flaw detection is the oldest and the most common. Frequency: All sound waves oscillate at a specific frequency, or number of vibrations or cycles per second, which we experience as pitch in the familiar range of audible sound. Velocity: The speed of a sound wave varies depending on the medium through which it is traveling, affected by the medium's density and elastic properties. Wavelength: Any type of wave will have an associated wavelength, which is the distance between any two corresponding points in the wave cycle as it travels through a medium.
Wavelength is a limiting factor that controls the amount of information that can be derived from the behavior of a wave. Modes of Propagation: Sound waves in solids can exist in various modes of propagation that are defined by the type of motion involved. Variables Limiting Transmission of Sound Waves: The distance that a wave of a given frequency and energy level will travel depends on the material through which it is traveling.
Reflection at a Boundary: When sound energy traveling through a material encounters a boundary with another material, a portion of the energy will be reflected back and a portion will be transmitted through.
Angle of Reflection and Refraction: Sound energy at ultrasonic frequencies is highly directional and the sound beams used for flaw detection are well defined. Sound energy that is transmitted from one material to another bends in accordance with Snell's Law of refraction. This relationship is an important factor in angle beam testing, which is discussed in Section 4. In the broadest sense, a transducer is a device that converts energy from one form to another.
Typical transducers for ultrasonic flaw detection utilize an active element made of a piezoelectric ceramic, composite, or polymer.
Further details on the advantages of various transducer types, as well as the range of frequencies and diameters offered, may be found in the transducer section of our web site. Modern ultrasonic flaw detectors such as the EPOCH series are small, portable, microprocessor-based instruments suitable for both shop and field use. Modern flaw detectors typically capture a waveform digitally and then perform various measurement and analysis function on it. Internal data loggers can be used to record full waveform and setup information associated with each test, if required for documentation purposes, or selected information like echo amplitude, depth or distance readings, or presence or absence of alarm conditions. Sound energy will travel to the far side of a part, but reflect earlier if a laminar crack or similar discontinuity is presented. In some specialized cases, testing is performed in a through transmission mode, where sound energy travels between two transducers placed on opposite sides of the test piece.
Typical angle beam assemblies make use of mode conversion and Snell's Law to generate a shear wave at a selected angle (most commonly 30, 45, 60, or 70 degrees) in the test piece. The angled sound beam is highly sensitive to cracks perpendicular to the far surface of the test piece (first leg test) or, after bouncing off the far side, to cracks perpendicular to the coupling surface (second leg test).
Signs of non-small cell lung cancer include a cough that doesn't go away and shortness of breath. Tests that examine the lungs are used to detect (find), diagnose, and stage non-small cell lung cancer.
A thin membrane called the pleura covers the outside of each lung and lines the inside wall of the chest cavity. The pleural cavity normally contains a small amount of fluid that helps the lungs move smoothly in the chest when you breathe.
There are two main types of lung cancer: non-small cell lung cancer and small cell lung cancer.
Other less common types of non-small cell lung cancer are: pleomorphic, carcinoid tumor, salivary gland carcinoma, and unclassified carcinoma. Tests and procedures to detect, diagnose, and stage non-small cell lung cancer are often done at the same time. Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. Laboratory tests : Medical procedures that test samples of tissue, blood, urine, or other substances in the body. CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the chest, taken from different angles. Sputum cytology : A procedure in which a pathologist views a sample of sputum (mucus coughed up from the lungs) under a microscope, to check for cancer cells.


Fine-needle aspiration (FNA) biopsy of the lung: The removal of tissue or fluid from the lung using a thin needle. Bronchoscopy : A procedure to look inside the trachea and large airways in the lung for abnormal areas. Thoracoscopy : A surgical procedure to look at the organs inside the chest to check for abnormal areas. Thoracentesis : The removal of fluid from the space between the lining of the chest and the lung, using a needle.
Light and electron microscopy : A laboratory test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells. Immunohistochemistry : A test that uses antibodies to check for certain antigens in a sample of tissue. Whether the cancer has mutations (changes) in certain genes, such as the epidermal growth factor receptor (EGFR) gene or the anaplastic lymphoma kinase (ALK) gene. A high performance method of tracing specular rays also reduces cost compared to standard ray tracing.
Our formulation computes sound propagation paths from source to receiver and exploits the independence of visibility tests and validation tests to dynamically guide the simulation to high accuracy and performance. Since the 1940s, the laws of physics that govern the propagation of sound waves through solid materials have been used to detect hidden cracks, voids, porosity, and other internal discontinuities in metals, composites, plastics, and ceramics.
Basic Theory: Sound waves are simply organized mechanical vibrations traveling through a medium, which may be a solid, a liquid, or a gas.
Human hearing extends to a maximum frequency of about 20,000 cycles per second (20 KHz), while the majority of ultrasonic flaw detection applications utilize frequencies between 500,000 and 10,000,000 cycles per second (500 KHz to 10 MHz). Different types of sound waves (see Modes of Propagation, below) will travel at different velocities.
In ultrasonic flaw detection, the generally accepted lower limit of detection for a small flaw is one-half wavelength. Longitudinal waves and shear waves are the most common modes employed in ultrasonic flaw detection.
Most commonly, shear waves are generated in a test material by introducing longitudinal waves at a selected angle. As a general rule, materials that are hard and homogeneous will transmit sound waves more efficiently than those that are soft and heterogeneous or granular. For a given application, transducer frequency should be selected to optimize these variables. The amount of energy reflected, or reflection coefficient, is related to the relative acoustic impedance of the two materials. Virtually all of the sound energy is reflected from a crack or other discontinuity in the path of the wave.
In situations where sound reflects off a boundary, the angle of reflection equals the angle of incidence.
Ultrasonic transducers convert electrical energy into high frequency sound energy and vice versa. When this element is excited by a high voltage electrical pulse, it vibrates across a specific spectrum of frequencies and generates a burst of sound waves. Because sound energy at ultrasonic frequencies does not travel efficiently through gasses, a thin layer of coupling liquid or gel is normally used between the transducer and the test piece.
They introduce sound energy perpendicular to the surface, and are typically used for locating voids, porosity, and cracks or delaminations parallel to the outside surface of a part, as well as for measuring thickness.
They are used to improve near surface resolution and also in high temperature testing, where the delay line protects the active element from thermal damage. They are used in automated scanning applications and also in situations where a sharply focused beam is needed to improve flaw resolution. They are often used in applications involving rough surfaces, coarse grained materials, detection of pitting or porosity, and they offer good high temperature tolerance as well.
They generate and display an ultrasonic waveform that is interpreted by a trained operator, often with the aid of analysis software, to locate and categorize flaws in test pieces. While some analog-based flaw detectors are still manufactured, most contemporary instruments use digital signal processing for improved stability and precision. It provides an excitation pulse to drive the transducer, and amplification and filtering for the returning echoes. A clock or timer will be used to synchronize transducer pulses and provide distance calibration. Alarm gates are often employed to monitor signal levels at selected points in the wave train to flag echoes from flaws.
Using appropriate reference standards along with a knowledge of sound wave propagation and generally accepted test procedures, a trained operator identifies specific echo patterns corresponding to the echo response from good parts and from representative flaws.


If a large flaw is present in the sound path, the beam will be obstructed and the sound pulse will not reach the receiver.
As the angle of an incident longitudinal wave with respect to a surface increases, an increasing portion of the sound energy is converted to a shear wave in the second material, and if the angle is high enough, all of the energy in the second material will be in the form of shear waves. First, energy transfer is more efficient at the incident angles that generate shear waves in steel and similar materials. A variety of specific beam angles and probe positions are used to accommodate different part geometries and flaw types, and these are described in detail in appropriate inspection codes and procedures such as ASTM E-164 and the AWS Structural Welding Code. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. A history of the patient’s health habits, including smoking, and past jobs, illnesses, and treatments will also be taken. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
The antibody is usually linked to a radioactive substance or a dye that causes the tissue to light up under a microscope. Our method makes no assumptions of scene layout and can account for moving sources, receivers, and geometry. These waves will travel through a given medium at a specific speed or velocity, in a predictable direction, and when they encounter a boundary with a different medium they will be reflected or transmitted according to simple rules.
Three factors govern the distance a sound wave will travel in a given medium: beam spreading, attenuation, and scattering.
Acoustic impedance in turn is a material property defined as density multiplied by the speed of sound in a given material. Pulse amplitude, shape, and damping can be controlled to optimize transducer performance, and receiver gain and bandwidth can be adjusted to optimize signal-to-noise ratios. The echo pattern from an test piece may then be compared to the patterns from these calibration standards to determine its condition.
Second, minimum flaw size resolution is improved through the use of shear waves, since at a given frequency, the wavelength of a shear wave is approximately 60% the wavelength of a comparable longitudinal wave. Oxygen is inhaled into the lungs and passes through the thin membranes of the alveoli and into the bloodstream (see inset). A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly.
We combine our guidance algorithm with a fast GPU sound propagation system for interactive simulation. In ultrasonic thickness gaging, the theoretical minimum measurable thickness one wavelength.
This procedure is also called computed tomography, computerized tomography, or computerized axial tomography. A small incision may be made in the skin where the biopsy needle is inserted into the abnormal tissue or fluid. It may also have a tool to remove tissue samples, which are checked under a microscope for signs of cancer.EnlargeBronchoscopy. Our implementation efficiently computes early specular paths and first order diffraction with a multi-view tracing algorithm. A bronchoscope is inserted through the mouth, trachea, and major bronchi into the lung, to look for abnormal areas. We couple our propagation simulation with an audio output system supporting a high order interpolation scheme that accounts for attenuation, cross-fading, and delay. The resulting system can render acoustic spaces composed of thousands of triangles interactively. A chest x-ray is done after the procedure to make sure no air is leaking from the lung into the chest.EnlargeFine-needle aspiration biopsy of the lung.
The patient lies on a table that slides through the computed tomography (CT) machine, which takes x-ray pictures of the inside of the body. A biopsy needle is inserted through the chest wall and into the area of abnormal lung tissue.
A small piece of tissue is removed through the needle and checked under the microscope for signs of cancer.



The secret language of forest creatures
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