Sensor Review

Robert Bogue

2011 Sensor Review

doi: 10.1108/02602281111169703

Purpose – The purpose of this paper is to review the applications of commercially available fibre optic sensors (FOSs) and consider the reasons for their use. Design/methodology/approach – Following a short introduction, the paper discusses the applications of FOSs for physical variables, gases and chemical compounds and identifies the reasons for their use. Findings – It is shown that, following over three decades of research, FOSs are employed in many physical sensing uses where particular, application‐specific features confer significant user benefits. They are employed to a far lesser extent to monitor gases and chemical compounds, where the intrinsic features of the technology are of less benefit. Originality/value – This paper provides an account of the applications of FOSs that have emerged since their development in the 1970s.

Robert Bogue

2011 Sensor Review

doi: 10.1108/02602281111169712

Purpose – The purpose of this paper is to review recent developments in the sensing of electromagnetic radiation (EMR) with wavelengths longer than those of visible light. Design/methodology/approach – Following a short introduction, this paper discusses recent research into the sensing of infra‐red (IR), terahertz (THz) and microwave radiation. Findings – It is shown that novel sensors are being developed for all of these classes of EMR. Improved IR sensors are attracting strong interest from the military, novel THz sensor developments reflect the growing uses of this radiation and research into cosmology and astronomy are driving the development of highly sensitive microwave sensors. Originality/value – The paper provides a technical review of recent research into sensing IR, THz and microwave radiations.

Wei Wang; Hairui Yang

2011 Sensor Review

doi: 10.1108/02602281111169721

Purpose – Rectangular fluidised beds are commonly used in industry, e.g. circulating fluidised bed (CFB) boilers. Apparently, no one has tried to imagine rectangular fluidised beds by electrical capacitance tomography (ECT). The purpose of this paper is to design a rectangular ECT sensor to understand the behaviour of a rectangular CFB riser. Design/methodology/approach – A rectangular sensor with eight electrodes is adopted to obtain the capacitance data. The sensitivity map is simulated to calculate the grey level of pixels for visualisation using the linear back‐projection algorithm. Findings – Experiments showed that the position of the objects in the riser can be obviously indicated and the central region of the object(s) has significantly higher grey level than other regions in the images using the rectangular ECT sensor. Research limitations/implications – It has a limitation in providing a higher resolution image. Practical implications – The results obtained by the rectangular ECT sensor show that it is promising to study the characteristics of flow non‐uniformity in the fast fluidisation regime of CFB. Originality/value – Without using square and circular ECT sensors, this is the first time a rectangular ECT sensor has been developed to study the unique problems of the characteristics of flow non‐uniformity in a rectangular CFB riser.

Stephen J. Mihailov; Dan Grobnic; Christopher W. Smelser; Robert B. Walker; Ping Lu; Huimin Ding

2011 Sensor Review

doi: 10.1108/02602281111169730

Purpose – The purpose of this paper is to present a review of research performed at the Communications Research Centre Canada on sensing applications of femtosecond infrared laser‐inscribed Bragg gratings. Design/methodology/approach – By using fibre Bragg gratings induced with ultrafast infrared radiation, inscription of high temperature stable sensors in standard and exotic optical waveguides is investigated for a variety of novel applications. Findings – Generally, femtosecond laser‐induced gratings are effective sensors that can be applied in situations and environments where most fibre optic sensors are not effective. Originality/value – The paper is a review of existing work already published in the literature and provides an overview of this technology to the reader.

Mohammad Reza Badello; Behzad Moshiri; Babak N. Araabi; Hamed Tebianian

2011 Sensor Review

doi: 10.1108/02602281111169749

Purpose – The purpose of this paper is to design and implement a landmine detection robot (Venus) equipped with three electromagnetic sensors and controlled by ordered weighted averaging (OWA) sensor fusion approach. Higher numbers of detected mines in a fixed time interval and lower total power consumption are the achieved goals of this research. Design/methodology/approach – OWA sensor fusion is exploited for data combination in this paper. Unlike most other landmine detection robots, Venus has three electromagnetic sensors, the positions of which can be adjusted according to the environmental conditions. Also, a novel approach for OWA weight dedication using Gaussian distribution function is applied and the whole idea is evaluated practically in several randomly mined fields. Finally, for better evaluation, performance of Venus is compared with the other two landmine detection robots. Findings – The simulation and experimental results proved that in a predetermined interval of time, not only total energy consumption is reduced, but also by expanding the surface and the depth of influence of electromagnetic waves, the number of detected mines is considerably raised. Social implications – In contrast to the regular demining process, which is relatively expensive and complicated, the landmine detection method proposed in this research is surprisingly simple, cost effective, and efficient. Therefore, it may be attractive for every company or organization in this field of research. Originality/value – The paper describes research which implements and evaluates a novel control approach based on OWA sensor fusion method, a new way of using Gaussian distribution function for determining OWA weights, and also an adaptive physical configuration for sensors based on environmental conditions.

Cheng Zhong; Hui Li; Xianfeng Huang

2011 Sensor Review

doi: 10.1108/02602281111169758

Purpose – Orthophoto suffers from the relief displacement effects magnified by high resolution imaging sensors especially when mapping urban areas. True orthophotos eliminating relief displacement with digital surface model (DSM) are presented to assure reliable interpretability and maintain the high quality of the available data. Previous efforts did not provide accurate and fast ways for generating true othorphoto. The purpose of this paper is to try to solve the problem by analyzing the complexity of algorithm processes and finding the optimum manner to allocate them. Design/methodology/approach – In this paper, an optimum segmentation number for radial sweep is presented to achieve minimum complexity. First, the scan area, number of azimuth lines and visibility judgment area of radial sweep and spiral sweep method have been discussed with rigorous geometric theory, and then algorithm complexities of both methods are estimated with mathematical computation theory. Finally, minimum complexity of the methods is obtained with extreme point theory of differential calculus. Findings – Experiments have demonstrated that the proposed method has the best efficiency, and is efficient to avoid “M‐potion” problem, and false occlusions and false visibilities caused by the rolling area, the incompatibility between the DSM and ground image resolution. Originality/value – The deduction and experiments indicate that the proposed method is a robust, accurate, fast, and effective approach to generate high quality, true orthophoto at a large‐scale.

Yanling Wang

2011 Sensor Review

doi: 10.1108/02602281111169767

Purpose – The purpose of this paper is to present an imperceptible and robust watermarking algorithm with high embedding capacity for digital images based on discrete wavelet transform (DWT) domain. Design/methodology/approach – First, the watermark image is scrambled using chaotic sequence and mapped to avoid the block effect after embedding watermark into the host image. Then, the scrambled watermark is inserted in LH 2 and HL 2 sub‐bands of the DWT of the host image to provide a good tradeoff between the transparency and the robustness of watermarks. Findings – This paper presents experimental results and compares the results to other methods. It can be seen from the comparison that this method can obtain a better performance in many cases. Originality/value – One of the main differences of this technique, compared to other wavelet watermarking techniques, is in the selection of the wavelet coefficients of the host image. When performing second level of the DWT, most methods in the current literature select the approximation sub‐band (LL 2 ) to insert the watermark. The technique presented in this paper decomposes the image using DWT twice, and then obtains the significant coefficients (LH 2 and HL 2 sub‐bands) of the host image to insert the watermark.

Kin Yen; Mani Ratnam

2011 Sensor Review

doi: 10.1108/02602281111169776

Purpose – Researchers in the past have used Fourier transformation method to determine the in‐plane displacement components from moiré fringes generated by a pair of overlapping circular gratings. In this approach it is necessary to assume that the transmittance is sinusoidal. The purpose of this paper is to propose a graphical method for determining the 2D displacement components from the moiré patterns more easily instead of the complex Fourier transformation method. Design/methodology/approach – The moiré patterns were spatially transformed from Cartesian‐to‐polar coordinate system. The morphological grayscale dilation operation was used to eliminate the residual gratings in the transformed pattern while preserving the moiré fringes. The center line of the moiré fringe was fitted with a sine curve and the in‐plane displacement values were determined directly from the peak‐to‐valley height and the position of the peak in the fitted curve. Findings – Experimental results showed that the proposed moiré pattern analysis method is able to give in‐plane displacement accuracies of 0.002 mm in the x ‐direction and 0.01 in the y ‐direction without the need for complex computation. Research limitations/implications – Resolution of the proposed method is limited only by the resolution of the imaging system. Practical implications – The proposed graphical method for determining 2D displacement components from the moiré patterns can be applied to low‐frequency circular gratings whose transmittance is not sinusoidal. Originality/value – The graphical analysis method is novel and allows the displacements components to be determined more easily.