With the prevalence of WiFi devices (e.g., smartphones), many new business opportunities are being spawned by exploiting the routes or locations of users. Nevertheless, most current approaches based on received signal...
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ISBN:
(纸本)9781538621950
With the prevalence of WiFi devices (e.g., smartphones), many new business opportunities are being spawned by exploiting the routes or locations of users. Nevertheless, most current approaches based on received signal strength indicator (RSSI) usually assume that the targeted (tracked) devices have the transmission characteristics similar to the devices used for system training. This is far from the reality and may lead to considerable errors. We propose a robust localization approach which automatically infers a customized signal-strength-to-distance function for every device on-the-fly, and simultaneously estimates the location of it. This is achieved by first approximating the function with a set of piecewise linear functions, for each targeted device, and the parameters of the linear functions are updated, with an Expectation Maximum (EM) algorithm, when more and more RSSI data of the device are available. Specifically, during the expectation step of the EM algorithm, the location of the targeted device is estimated. Whereas in the maximization step of the algorithm, the parameters of the linear functions customized for that device are updated. As the approach is capable of learning the parameters during localization, training process or system calibration is unnecessary and thus the system setup time can be shortened. This feature is practical for meeting the special needs of the exhibition industry: extremely tight schedules for setting up the site from scratch and extremely large venues. With our testbeds, experimental results show that the mean localization error can be kept about 1.7 meters for different mobile devices with different transmission characteristics. A real-world test at Hong Kong Convention and Exhibition Centre (HKCEC) was also conducted and various mobile devices can be tracked accurately with little setup time.
This conference proceedings contain 36 papers. The main subjects are: machine vision architectures, system integration and sensor interface configurations, industrial vision applications, and some unusual solutions fo...
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ISBN:
(纸本)0819410241
This conference proceedings contain 36 papers. The main subjects are: machine vision architectures, system integration and sensor interface configurations, industrial vision applications, and some unusual solutions for integrating machine vision systems.
Volcano-structured double-gated field emitter arrays (VDG-FEAs) have realized both highly focusing electron beam and high emission current. The prototype image sensor using Spindt-type VDG-FEA has obtained a reproduce...
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Brillouin scattering in an optical fiber can be used as distributed sensing mechanism for strain and/or temperature. With correlation domain techniques, mm-order spatial-resolution, kHz-order sampling-rate, random-acc...
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Fuel economy improvement and stringent emission regulations worldwide require advanced air charging and combustion technologies, such as low temperature combustion, PCCI or HCCI combustion. Furthermore, NO x aftertrea...
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Philips Imaging Technology has succeeded in fabricating an image sensor especially suited for digital image processing. The FT12 sensor is of the frame transfer type and designed for 2/3' optical format. It has a ...
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ISBN:
(纸本)0819414670
Philips Imaging Technology has succeeded in fabricating an image sensor especially suited for digital image processing. The FT12 sensor is of the frame transfer type and designed for 2/3' optical format. It has a high resolution (1024 x 1024 in interlaced mode), overexposure handling by means of vertical anti-blooming and square pixels of 7.5 micrometers by 7.5 micrometers . The data rate is 60 fields per second in interlaced mode. Its single output register can run up to 40 MHz. The register can be clocked bi-directionally, which makes it possible to produce a mirrored image. These properties make it perfectly suited for machine vision applications, like pattern recognition and real-time process monitoring. The paper describes the sensor, simulation results, measurements, as well as the implementation of the sensor in a camera module.
This paper describes a multispectral liquid drop analyzer for liquid chemical and physical properties analysis. Liquid drops formed at the tip of a liquid head are measured in parallel by a fiber sensor and a capaciti...
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ISBN:
(纸本)0819451525
This paper describes a multispectral liquid drop analyzer for liquid chemical and physical properties analysis. Liquid drops formed at the tip of a liquid head are measured in parallel by a fiber sensor and a capacitive sensor. The fiber sensor works as follows: multispectral light sources are injected into the drop through an optical fiber and the total internal reflections and absorptions are detected by a photo detector. By combining fiber and capacitive sensor outputs, a drop speed independent one-dimensional waveform (liquid fingerprint) is generated. Liquid surface tension, refractive index and di-electric constant can be estimated from the fingerprint. To compare two fingerprints, the sensor outputs are normalized to have the same unit of measurement and drop starting position. After that, a reference liquid based calibration is applied to correct of fingerprint distortion due to variations in environmental conditions, such as changes in temperature and humidity. Finally, a normalized correlation algorithm analyses the fingerprint difference. The repeatability and sensitivity of the system are demonstrated using different liquid samples. On-line applications show that the analyzer is able to detect 2% change in alcohol density.
Techniques which apply tunable quantum cascade lasers (QCLs) for target illumination suffer from fluctuations of the laser beam direction. This manuscript describes a method to stabilize the beam direction by using an...
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ISBN:
(纸本)9781510608894;9781510608900
Techniques which apply tunable quantum cascade lasers (QCLs) for target illumination suffer from fluctuations of the laser beam direction. This manuscript describes a method to stabilize the beam direction by using an active feedback loop. This approach corrects and stabilizes the laser pointing direction using the signal from a 4-element photo sensor as input to control an active 2 dimensional Galvo mirror system. Results are presented for measurements using known perturbations as well as actual mode hops intrinsic to external cavity QCL during wavelength tuning.
The counterfeiting and recycling of integrated circuits (ICs) have become major problems in recent years, potentially impacting the security of electronic systems bound for military, financial, or other critical appli...
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ISBN:
(纸本)9781450311991
The counterfeiting and recycling of integrated circuits (ICs) have become major problems in recent years, potentially impacting the security of electronic systems bound for military, financial, or other critical applications. With identical functionality and packaging, it is extremely difficult to distinguish recovered ICs from unused ICs. A technique is proposed to distinguish used ICs from the unused ones using a fingerprint generated by a light-weight on-chip sensor. Using statistical data analysis, process and temperature variations' effects on the sensors can be separated from aging experienced by the sensors in the ICs when used in the field. Simulation results, featuring the sensor using 90nm technology, and silicon results from 90nm test chips demonstrate the effectiveness of this technique for identification of recovered ICs.
The dark current that arises due to diffusion from the bulk is assuming a more important role now that CCD and CMOS image sensors have found their way into consumer electronics which must be capable of operating at el...
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ISBN:
(纸本)9780819489456
The dark current that arises due to diffusion from the bulk is assuming a more important role now that CCD and CMOS image sensors have found their way into consumer electronics which must be capable of operating at elevated temperatures. Historically this component has been estimated from the diffusion related current of a diode with an infinite substrate. This paper explores the effect of a substrate of finite extent beneath the collecting volume of the pixel for a front-illuminated device and develops a corrected expression for the diffusion related dark current. The models show that the diffusion dark current can be much less than that predicted by the standard model.
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