[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

A scheme is developed for classifying the types of motion perceived by a humanlike robot. It is assumed that the robot receives visual images of the scene using a perspective system model. Equations, theorems, concepts, clues, etc., relating the objects, their positions, and their motion to their images on the focal plane are presented. >

http://ieeexplore.ieee.org/iel2/815/3148/00100651.pdf

Robot vision

/pdf/remote-sensing-of-the-environment-4yfxjaaswe.pdf

Remote sensing of the environment

This paper provides a comprehensive review of the domain of physical layer security in multiuser wireless networks. The essential premise of physical layer security is to enable the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers, without relying on higher-layer encryption. This can be achieved primarily in two ways: without the need for a secret key by intelligently designing transmit coding strategies, or by exploiting the wireless communication medium to develop secret keys over public channels. The survey begins with an overview of the foundations dating back to the pioneering work of Shannon and Wyner on information-theoretic security. We then describe the evolution of secure transmission strategies from point-to-point channels to multiple-antenna systems, followed by generalizations to multiuser broadcast, multiple-access, interference, and relay networks. Secret-key generation and establishment protocols based on physical layer mechanisms are subsequently covered. Approaches for secrecy based on channel coding design are then examined, along with a description of inter-disciplinary approaches based on game theory and stochastic geometry. The associated problem of physical layer message authentication is also briefly introduced. The survey concludes with observations on potential research directions in this area.

/pdf/principles-of-physical-layer-security-in-multiuser-wireless-3w4jvwpgy4.pdf

Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey

In this paper, we propose a unified framework to generate a pleasant and high-quality street-view panorama by stitching multiple panoramic images captured from the cameras mounted on the mobile platform. Our proposed framework is comprised of four major steps: image warping, color correction, optimal seam line detection and image blending. Since the input images are captured without a precisely common projection center from the scenes with the depth differences with respect to the cameras to different extents, such images cannot be precisely aligned in geometry. Therefore, an efficient image warping method based on the dense optical flow field is proposed to greatly suppress the influence of large geometric misalignment at first. Then, to lessen the influence of photometric inconsistencies caused by the illumination variations and different exposure settings, we propose an efficient color correction algorithm via matching extreme points of histograms to greatly decrease color differences between warped images. After that, the optimal seam lines between adjacent input images are detected via the graph cut energy minimization framework. At last, the Laplacian pyramid blending algorithm is applied to further eliminate the stitching artifacts along the optimal seam lines. Experimental results on a large set of challenging street-view panoramic images captured form the real world illustrate that the proposed system is capable of creating high-quality panoramas.

A Unified Framework for Street-View Panorama Stitching.

Eddy current pulsed thermography (ECPT) and long pulse optical thermography (LPOT) as two emerging nondestructive testing and evaluation (NDT&E) techniques have been recently used for defect evaluation in many scenarios. This paper focuses on detecting the flat bottom hole (FBH) defects in an aluminium specimen by using both techniques. Principal component analysis (PCA) is used to enhance the FBH detection. The comparative results show that although LPOT has the advantage of a larger detection area and higher efficiency, the ECPT has a better performance compared to LPOT in detecting FBH defects in the aluminium specimen.

Comparative Study of Eddy Current Pulsed and Long Pulse Optical Thermography for Defect Detection in Aluminium Plate

In this paper, an innovative Compressed Sensing (CS) framework has been proposed with the purpose of providing a sub-Nyquist sampling mechanism to Electromagnetic Acoustic Transducer (EMAT) testing. Particularly, a novel sparse representation method based on dictionary learning was introduced into the CS framework aimed at a more efficient signal sparse representation and more accurate signal reconstruction. The proposed CS framework was examined through a process of thickness measurement of an 813-X70 pipeline. Experimental results indicated that the thickness feature of the specimen could be precisely extracted from the recovered data with 20% of compression ratio compared with conventional sampling method. It demonstrates that the CS theorem can significantly reduce the required sampling rate of EMAT testing system without loss of signal resolution, thus improves the overall testing efficiency.

Application of Compressed Sensing on Eletromagetic Transducer Testing

Sensors’ signal conditioning and digital interface are important for sensor technologies, digital transformation, and the Internet of Things (IoT) in particular. Frequency output sensors and inductance-to-digital converters (LDC) offer distinct advantages over Analog-to-Digital Converter (ADC) interfaces. To miniaturize the eddy current testing system and achieve multi-parameter measurements, this paper reviews eddy current signal conditioning and digital interfaces in the field of displacement sensors and non-destructive tests & evaluation (NDT&E). After review and comparison of different signal conditioning and digital interfaces, the LDC chip is used in eddy current testing for multiple parameter measurements including lift-off distance and defect detection. An LDC-based integrative eddy current non-destructive testing method is proposed. The LDC chip provides AC to drive the LC resonator composed of the sensor coil and the parallel capacitor. By measuring the resonance frequency and parallel resistance (Rp) of the LC resonator, the simultaneous measurement of the lift-off distance and the defect is achieved. Based on the method, the testing experiments of two kinds of specimens made of aluminium and steel were carried out under different lift-offs. Experimental results show that both parameters of frequency and Rp of the LC resonator can intuitively reflect the defect depth and lift-off. Frequency- Rp curves can be used to quantify defect depth and lift-off distance and differentiate the material. This work also illustrates an integrated approach of signal conditioning and digital interface for multiple parameters or feature measurement for integrated eddy current NDT&E. The work opens a new way for addressing multiple parameter measurements of eddy current NDT & E including lift-off estimation and defect characterization via digital interfaces. It has the potential to bridge the gaps in metrology of geometry, displacement measurement, and NDT&E for defect detection and material characterization. 

Inductance-to-digital converters (LDC) based integrative multi-parameter eddy current testing sensors for NDT&E

The pulsed eddy current (PEC) technique as complementary approach of traditional eddy current method has found increasing applications in deep flaw detection and complex structure inspection. Considering the present PEC NDE (non-destructive evaluation) needs valid algorithms and techniques to implement signal processing in time domain, the novel statistical technique based on principle component analysis (PCA) and independent component analysis (ICA) is proposed to extract defective information from transient PEC signals and evaluate flaw inspection during the PEC detection. The presented results of defect classification associated with different flaw types validated the feasibility of proposed technique in this paper.

Novel statistical technique of defective information extraction in pulsed eddy current NDE

Wheel-rail contact force measurement is one of the key issues in rolling stock monitoring. Traditional methods using strain gauges are a relative measurement, which require strong bonding on the wheel webs with complicated telemetry transmission systems. This paper proposes a wireless inductive-capacitive (LC) resonance sensing approach for non-contact measurement of wheel-rail contact forces. The proposed LC resonance sensor is low-cost, high sensitivity, and consists of a dual-layer rectangular inductance coil and a parallel capacitor. Validation using a standard dog-bone specimen tested on a universal testing machine was performed, with the resonant frequency of the proposed LC resonance sensor increasing monotonically with loading force. Investigation of lift-off and aspect ratio of the inductance coil shows that lower lift-off and lower aspect ratio offer better sensitivity. The proposed LC resonance sensing with LDC chip approach has great potential for rolling stock monitoring. 

Gui Yun Tian

Papers

Comparative Study of Eddy Current Pulsed and Long Pulse Optical Thermography for Defect Detection in Aluminium Plate

Application of Compressed Sensing on Eletromagetic Transducer Testing

Inductance-to-digital converters (LDC) based integrative multi-parameter eddy current testing sensors for NDT&E

Novel statistical technique of defective information extraction in pulsed eddy current NDE

Wheel-rail Force Measurement Based on Wireless LC Resonance Sensing