In this paper we performed 2D and 3D device simulations to analyze the impact of technology scaling on the lattice heating in n-channel bulk silicon and silicon-on-insulator MOS transistors with gate lengths from 0.5 to 0.1 um. Maximum lattice temperatures and transistor thermal resistances for different gate lengths and bias voltages were calculated. The increase in device temperature and thermal resistance with transistor scaling was shown.
The most important task in Moscow metro is increasing safety of railway traffic. For safety purposes six track parameters are measured in Moscow Metro with help of track measurement car. Equipment mounted on this car works only in contact mode and doesn't provide modem requirements for accuracy. Also important task is measurement at high speeds, but contact technology limits speed of movement up to 25mph on rail switches. Current system can't measure in real-time mode.
For decision of these field of tasks non-contact photonic measurement system (KSIR) is constructed. The KSIR works at speeds up to 70 mph and measure seven track parameters.
The KSIR contains four subsystems: rail wear, height and track gauge measurement (BFSM); rail slump measurement (FTP); contact rail measurement (FKR); speed, level and car locating (USI).
KSIR contains five CCD matrix cameras, four line CCD cameras, five infrared stripe lasers and four spot infrared lasers.
Laser forms shape on the rail. CCD-camera acquires rail image and transfers it into the digital signal processor which produces preliminary calculation ofrail shape. Then image is transferred into the central computer to calculate values of rail characteristics.
Angles between photonic unit and rail bring distortions in images from cameras. Additional distortions are caused by short-focus optics and small distance between camera and track. This distance is limited by structure clearance. The transformation algorithms for distortions elimination are applied. It's based on surfaces spline-approximation. As a result the KSIR calculates coefficients of approximating polynomials. The calibration is performed for checking accuracy of measurement in BFSM, FTP and FKR units. Evaluation techniques of accuracy characteristics are considered.
Increasing of traffic speed is the most important task in Moscow Metro. Requirements for traffic safety grow up simultaneously with the speed increasing. Currently for track inspection in Moscow Metro is used track measurement car has built in 1954. The main drawbacks of this system are absence of automated data processing and low accuracy. Non-contact photonic measurement system (KSIR) is developed for solving this problem. New track inspection car will be built in several months. This car will use two different track inspection systems and car locating subsystem based on track circuit counting.
The KSIR consists of four subsystems: rail wear, height and track gauge measurement (BFSM); rail slump measurement (FIP); contact rail measurement (FKR); speed, level and car locating (USI). Currently new subsystem for wheel flange wear (IRK) is developed. The KSIR carry out measurements in real-time mode. The BFSM subsystem contains 4 matrix CCD cameras and 4 infrared stripe illuminators. The FIP subsystem contains 4 line CCD cameras and 4 spot illuminators. The FKR subsystem contains 2 matrix CCD cameras and 2 stripe illuminators. The IRK subsystem contains 2 CCD cameras and 2 stripe illuminators. Each system calibration was carried out for their adjustment. On the first step KSIR obtains data from photonic sensors which is valued in internal measurement units. Due to the calibration on the second step non-contact system converts the data to metric measurement system.
The safety of railway traffic depends on state of the track. About ten parameters are measured on Moscow Metropolitan for rail control. At present time the contact technology is used that doesn't provide required accuracy, limits speed of movement up to 25 mph and doesn't work in real-time mode.
Non-contact photonic measurement system (KSIR) is developed which can works at speeds up to 70 mph.
The KSIR consists of four subsystems: rail wear, height and track gauge measurement (BFSM); rail slump measurement (FIP); contact rail measurement (FKR); speed, level and car locating (USI).
KSIR contains five CCD matrix cameras, four line CCD cameras, five infrared stripe lasers and four spot infrared lasers. Preliminary image processing is carried out using digital signal processor.
The images from cameras are distorted because there is angle between photonic unit and rail. Additional distortions are caused by short-focus optics and small distance between camera and track. This distance is limited by structure clearance. For distortion eliminating is applied the transformation algorithms. It's based on surfaces spline-approximation. As a result the KSIR calculates coefficients of approximating polynomials. The calibration is performed for checking accuracy of measurement in BFSM, FIP and FKR units.
Image reconstruction algorithm for three-dimensional laser optoacoustic imaging system (LOIS) is proposed and tested in computer-simulating experiments. It was assumed that acoustic transducers were evenly distributed with 3-degree interval along polar and azimuthal angles on the surface of a 100-mm diameter hemisphere, all optoacoustic sources were located inside the hemisphere of a slightly smaller diameter. At the first stage of calculations, the initial data in a form of spherical surface integrals were converted into the plane surface integrals. We deduced an approximate analytical formula for this conversion. At the second stage, the three-dimensional Radon transform algorithm was applied for reconstruction of optoacoustic sources. Three- dimensional images of computer-simulated spherical objects were generated. Quality of reconstructed images was evaluated with the following four criteria: The noise level on the entire tomogram, the step-transfer function, the loss-of-contrast function and the contrast-dimension relation. These quality criteria may be employed to characterize any tomography systems regardless of the type of technology employed. Image analysis demonstrated that the artifact level associated with data conversion from spherical into planar coordinates did not exceed 10%. A 1-mm spatial resolution could be obtained with the proposed algorithm, provided the signal-to-noise ratio equals approximately 3 on the tomogram. Very small (0.5-mm diameter) and small (3-mm diameter) spherical tumors could be revealed on optoacoustic tomograms if their contrast equals at least 6 and 0.3, respectively.
The contact-free photon system of measurement of a rail track contains the subsystem of level measurement of an inclination of a rail track monitoring car, velocity of driving and sample of pickets. This subsystem is implemented on the basis of optoelectronic sensors and Complex Programmable Logic Device (CPLD). The format of the transmitted data surveyed the calculation of parameters for a given accuracy and speed range is reduced. The outcomes and structure of the subsystem is shown. The value of a velocity is determined in notebook by an amount of going impulses from the optoelectronic sensor.
At present there are exist comprehensive studies in the field of railway track condition monitoring systems and development of non-contact photonic systems (NCPS) based on digital CCD-cameras, high-speed board computers and powerful software. It consists of four special digital matrix CCD- cameras and four laser stripe illuminators. They are rigidly connected and structurally fixed on a wheel set of the track inspection vehicle in such manner that the corners of observation and the distances from the cameras up to the head of the rail during movement of the vehicle remain fixed. Distortions obtained when using Euler planes' formulas can be removed by applying coordinates conformity system. According to the algorithms made a cut-off method and tangent methods have been compared.
Mathematical model of image reconstruction for two-dimensional optoacoustic imaging system is described. It was assumed that receiving transducers are uniformly distributed along the perimeter of a 60 mm radius ring with 2.1 mm gaps between transducer centers and initial data were known with 0.1 mm increments. The algorithm of radial back projection with convolution was used for optoacoustic image reconstruction. The convolution was evaluated with modified Shepp-Logan (MSL) and rectangular (RECT) space spectrum windows. Linear interpolation was applied for calculation of the convolution at the intermediate space points. The following four criteria were employed for estimation of resulting image quality: noise level on entire tomogram, a jump transfer function, loss contrast function and the contrast-dimension reflation. Theoretical expressions for these parameters were derived and used for optimization of the proposed algorithm. Two-dimensional images of computer simulated spherical objects were reconstructed. It was shown that 0.1 mm spatial resolution could be obtained provided the signal-to-noise ratio equals approximately 3 at the tomogram. A very small (0.2 mm diameter) tumor and a small (2-mm diameter) tumor could be clearly revealed at the tomogram if their optical absorption contrast equals at least 2 and 0.1 respectively.
At present there are exist comprehensive studies in the field of railway track condition monitoring systems and development of non-contact photonic systems based on digital CCD-cameras, high-speed board computers and powerful software. Creation of such systems allows to conduct preventive track maintenance work beforehand and to avoid the effects of vibration from wavy rail defects on a wheel set. As a result, the safety of running, durability of permanent way and rolling-stock are increased and the maintenance costs are reduced. The system developed consists of four special digital matrix CCD-cameras and four laser stripe illuminators. An electronic interface for linking the computer with the cameras, contour extraction models of the rail profile have been developed and the analysis of input- output ports has been carried out. According to the algorithms make a cut-off method and a tangent method have been compared.