Zeitschriftenartikel: „Active sonar systems“

1

Zurk, Lisa, Jorge Quijano, Manish Velankar und Dan Rouseff. „Bistatic invariance for active sonar systems“. Journal of the Acoustical Society of America 120, Nr. 5 (November 2006): 3221. http://dx.doi.org/10.1121/1.4788183.

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2

Soules, Mary E., und Joshua B. Broadwater. „Featureless classification for active sonar systems.“ Journal of the Acoustical Society of America 127, Nr. 3 (März 2010): 2042. http://dx.doi.org/10.1121/1.3385378.

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3

La Cour, Brian R., Kevin Johnson und Son Quach. „Multisensor registration for distributed active sonar systems“. Journal of the Acoustical Society of America 116, Nr. 4 (Oktober 2004): 2647. http://dx.doi.org/10.1121/1.4785564.

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4

Jiang, Jiajia, Xianquan Wang, Fajie Duan, Chunyue Li, Xiao Fu, Tingting Huang, Lingran Bu, Ling Ma und Zhongbo Sun. „Bio-Inspired Covert Active Sonar Strategy“. Sensors 18, Nr. 8 (26.07.2018): 2436. http://dx.doi.org/10.3390/s18082436.

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The covertness of the active sonar is a very important issue and the sonar signal waveform design problem was studied to improve covertness of the system. Many marine mammals produce call pulses for communication and echolocation, and existing interception systems normally classify these biological signals as ocean noise and filter them out. Based on this, a bio-inspired covert active sonar strategy was proposed. The true, rather than man-made sperm whale, call pulses were used to serve as sonar waveforms so as to ensure the camouflage ability of sonar waveforms. A range and velocity measurement combination (RVMC) was designed by using two true sperm whale call pulses which had excellent range resolution (RR) and large Doppler tolerance (DT). The range and velocity estimation methods were developed based on the RVMC. In the sonar receiver, the correlation technology was used to confirm the start and end time of sonar signals and their echoes, and then based on the developed range and velocity estimation method, the range and velocity of the underwater target were obtained. Then, the RVMC was embedded into the true sperm whale call-train to improve the camouflage ability of the sonar signal-train. Finally, experiment results were provided to verify the performance of the proposed method.

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Kim, Suhwan, Bonhwa Ku, Wooyoung Hong und Hanseok Ko. „Performance comparison of target localization for active sonar systems“. IEEE Transactions on Aerospace and Electronic Systems 44, Nr. 4 (Oktober 2008): 1371–80. http://dx.doi.org/10.1109/taes.2008.4667715.

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6

Hjelmervik, Karl Thomas, und Geir Helge Sandsmark. „In ocean evaluation of low frequency active sonar systems“. Journal of the Acoustical Society of America 123, Nr. 5 (Mai 2008): 3434. http://dx.doi.org/10.1121/1.2934216.

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7

Xu, Luzhou, Jian Li und Akshay Jain. „Impact of strong direct blast on active sonar systems“. IEEE Transactions on Aerospace and Electronic Systems 51, Nr. 2 (April 2015): 894–909. http://dx.doi.org/10.1109/taes.2014.140442.

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8

Lepper, Paul A., und Denise Risch. „Sonar signal analysis: Biological consequences of out-of-band acoustic signals from active sonar systems“. Journal of the Acoustical Society of America 144, Nr. 3 (September 2018): 1920. http://dx.doi.org/10.1121/1.5068410.

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9

Stergiopoulos, Stergios. „Implementation of adaptive processing schemes in active and passive sonar systems“. Journal of the Acoustical Society of America 100, Nr. 4 (Oktober 1996): 2853. http://dx.doi.org/10.1121/1.416780.

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10

Kwak, ChulHyun, Myoung Jun Cheong und Jae-Kyun Ahn. „A clutter reduction algorithm based on clustering for active sonar systems“. Journal of the Acoustical Society of Korea 35, Nr. 2 (31.03.2016): 149–57. http://dx.doi.org/10.7776/ask.2016.35.2.149.

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11

Sun, Xu, und Ranwei Li. „Robust adaptive beamforming method for active sonar in single snapshot“. MATEC Web of Conferences 283 (2019): 03006. http://dx.doi.org/10.1051/matecconf/201928303006.

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Forming narrow beams is a useful way for active sonar to anti-reverberation when it works in the shallow water. High-resolution adaptive beamforming with the performance of narrow beamwidths and low sidelobe levels is a better and more efficient method, particularly in the scenario where the installation space for sonar array is limited, such as hull-mounted sonar. Due to the short duration of target echo signal in the complex and varying acoustic channel, conventional adaptive beamforming methods are invalid. Therefore, this paper proposes a robust adaptive beamforming method for active sonar in single snapshot, also called the steered dominant mode rejection (STDMR). Firstly, STDMR steered the sample covariance matrix (STCM) based on wide-band focusing, which the needed number of snapshots is greatly reduced. Secondly, by partial eigendecomposition, the large eigenvalues of the STCM which are greater than the noise energy and their eigenvectors are used for dominant mode rejection (DMR). DMR is a typical eigenspace-based algorithm which has small computational load and fast convergence speed. Finally, modified with the methods of diagonal loading of 3-5dB over the noise energy and signal mismatch protection, improved the robustness of this method. Simulation and experimental data analysis shows that the STDMR method achieves narrow beams and low-level sidelobes in single snapshot. Hence, the STDMR beamformer is an appropriate implementation to use for active sonar detection systems.

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HALEY, THOMAS B. „AN ASSSESSMENT OF THE IMPACT OF NEURAL NETWORK TECHNOLOGY ON AUTOMATIC ACTIVE SONAR CLASSIFIER DEVELOPMENT“. International Journal of Pattern Recognition and Artificial Intelligence 05, Nr. 04 (Oktober 1991): 645–54. http://dx.doi.org/10.1142/s0218001491000375.

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We have spent the last several years investigating likely roles for neural network technology in the automatic active underwater sonar classifier development process, including exploration of both the improvement of in-service sonar systems and the creation of new ones. Currently, numerous classifier studies place emphasis on comparing class distinction performance figures of neural networks to those of traditional classifiers. We find that, for active sonar classifiers, this approach provides an incomplete and sometimes misleading assessment of the value of neural network technology. It is demonstrated that it is meaningful to divide the classifier development process into its phases and evaluate the influence that the neural network approach has on each phase. Conclusions are drawn on the potential impact of neural network technology on the active sonar classifier development field, which may help provide motivation for areas of future research.

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Cortes Ciro, Andrés, und Ennio Emanuel Pinzón Villarroel. „Development of a Comparison Method of Sonar Systems for Surface Platforms“. Ciencia y tecnología de buques 8, Nr. 16 (23.01.2015): 9. http://dx.doi.org/10.25043/19098642.107.

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This work sought to study the models of acoustic signal propagation in marine environments according toopen literature currently available, by interpreting the different effects occurring during their propagationand their characteristic principal parameters; identifying models of underwater acoustic propagation thatmay occur and its corresponding simulation for its understanding. Software, denominated BELLFAT,was developed in Matlab, which permits predicting, evaluating, and analyzing the capabilities of anactive sonar system. Such can function by taking depth, temperature, salinity in the sea of any referencearea and the characteristics of the sonar to evaluate. Thus, this computational tool is established to studymarine sonar systems sought to be developed or as a key piece to establish the characteristics active sonarmust have for the purposes of a surface platform.

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Son, Woo-Sung, Young Kwang Seo, Wan-Jin Kim und Hyoung-Nam Kim. „Analysis on Signal Transmission Methods for Rapid Searching in Active SONAR Systems“. Journal of the Institute of Electronics and Information Engineers 55, Nr. 8 (31.08.2018): 83–93. http://dx.doi.org/10.5573/ieie.2018.55.8.83.

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15

Liang, Junli, Luzhou Xu, Jian Li und Petre Stoica. „On Designing the Transmission and Reception of Multistatic Continuous Active Sonar Systems“. IEEE Transactions on Aerospace and Electronic Systems 50, Nr. 1 (Januar 2014): 285–99. http://dx.doi.org/10.1109/taes.2013.130256.

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16

Ki Man Kim, Chungyong Lee und Dae Hee Youn. „Adaptive processing technique for enhanced CFAR detecting performance in active sonar systems“. IEEE Transactions on Aerospace and Electronic Systems 36, Nr. 2 (April 2000): 693–700. http://dx.doi.org/10.1109/7.845261.

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17

Guan, Chengyu, Zemin Zhou und Xinwu Zeng. „Optimal Waveform Design Using Frequency-Modulated Pulse Trains for Active Sonar“. Sensors 19, Nr. 19 (30.09.2019): 4262. http://dx.doi.org/10.3390/s19194262.

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Frequency-modulated pulse trains can be applied in active sonar systems to improve the performance of conventional transmitted waveforms. Recently, two pulse trains have been widely researched as the transmitted waveforms for active sonars. The LFM-Costas pulse train was formed by modulating the linear frequency-modulated (LFM) waveform via the Costas sequence to remove the Doppler ambiguity of LFM pulses. The generalized sinusoidal frequency-modulated (GSFM) waveform, another frequency-modulated pulse train, achieved an ideal ambiguity function shape with thumbtack mainlobe. In this paper, we focus on constructing an optimization model to optimize the LFM-Costas and GSFM pulse trains with the genetic algorithm. The pulse trains can be improved on properties of both ambiguity function and correlations between sub-pulses. The optimized pulse trains are proven to have better detection performance than those of the initial pulse trains, including the lower sidelobe levels of ambiguity function, as well as lower cross-correlation property. Moreover, it is affirmed that the reverberation suppression performance of pulse trains has also been improved through the optimization model.

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Ling, Jun, Luzhou Xu und Jian Li. „Adaptive Range-Doppler Imaging and Target Parameter Estimation in Multistatic Active Sonar Systems“. IEEE Journal of Oceanic Engineering 39, Nr. 2 (April 2014): 290–302. http://dx.doi.org/10.1109/joe.2013.2249851.

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Huang, Shuxia, Shiliang Fang und Ning Han. „An Improved Velocity Estimation Method for Wideband Multi-Highlight Target Echoes in Active Sonar Systems“. Sensors 18, Nr. 9 (24.08.2018): 2794. http://dx.doi.org/10.3390/s18092794.

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In active sonar systems, the target echoes are usually equivalent to a superposition of the Doppler-scaled reflections from multiple highlights. The reflections overlap with each other both in the time and frequency domain, which results in a decreased velocity estimation performance. Recently, the hyperbolic-frequency modulated signal has been widely employed in sonar systems for moving targets due to its Doppler tolerance, while the precise velocity estimation becomes a great challenge under such conditions. In this paper, the echo c is modeled onsidering a target with a constant velocity and multi-highlights. The velocity estimation performance is analyzed though the signal’s matched filter and the wideband ambiguity function. An improved method based on the sliding window matching algorithm is proposed to improve the performance. The method controls the energy of environmental noise and interference by focusing on the dominant target highlight, and applying a designed window which utilizes the Doppler characteristics of hyperbolic-frequency modulated signals. Simulations and lake experiment allow us to compare between the improved method and the conventional matched filter method. The results verify the influence of the multi-highlights in velocity estimation and indicate that the improved method has more effective performance.

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Stergiopoulos, S. „Implementation of adaptive and synthetic-aperture processing schemes in integrated active-passive sonar systems“. Proceedings of the IEEE 86, Nr. 2 (1998): 358–98. http://dx.doi.org/10.1109/5.659491.

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21

Hague, David A., und John R. Buck. „An experimental evaluation of the generalized sinusoidal frequency modulated waveform for active sonar systems“. Journal of the Acoustical Society of America 145, Nr. 6 (Juni 2019): 3741–55. http://dx.doi.org/10.1121/1.5113581.

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22

DURA-BERNAL, SALVADOR, GUILLAUME GARREAU, JULIUS GEORGIOU, ANDREAS G. ANDREOU, SUSAN L. DENHAM und THOMAS WENNEKERS. „MULTIMODAL INTEGRATION OF MICRO-DOPPLER SONAR AND AUDITORY SIGNALS FOR BEHAVIOR CLASSIFICATION WITH CONVOLUTIONAL NETWORKS“. International Journal of Neural Systems 23, Nr. 05 (07.08.2013): 1350021. http://dx.doi.org/10.1142/s0129065713500214.

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The ability to recognize the behavior of individuals is of great interest in the general field of safety (e.g. building security, crowd control, transport analysis, independent living for the elderly). Here we report a new real-time acoustic system for human action and behavior recognition that integrates passive audio and active micro-Doppler sonar signatures over multiple time scales. The system architecture is based on a six-layer convolutional neural network, trained and evaluated using a dataset of 10 subjects performing seven different behaviors. Probabilistic combination of system output through time for each modality separately yields 94% (passive audio) and 91% (micro-Doppler sonar) correct behavior classification; probabilistic multimodal integration increases classification performance to 98%. This study supports the efficacy of micro-Doppler sonar systems in characterizing human actions, which can then be efficiently classified using ConvNets. It also demonstrates that the integration of multiple sources of acoustic information can significantly improve the system's performance.

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Liu, Dali, Lei Li und Xinhong Chen. „Optimization of Orthogonal MSK Waveforms for Active Sonar Using Genetic Algorithm“. Journal of Advanced Computational Intelligence and Intelligent Informatics 23, Nr. 1 (20.01.2019): 84–90. http://dx.doi.org/10.20965/jaciii.2019.p0084.

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In order to solve the high peak to average power ratio (PAPR) problem of pseudo random code phase modulation (PRCPM) signals, minimum shift keying (MSK) modulation waveforms with constant envelope were introduced into underwater detection. Genetic algorithm (GA) was proposed to optimize pseudo random binary codes used for MSK waveforms, in order to design sonar waveforms with various performances. After MSK complex envelope signal was obtained by theoretical analysis, the optimizing objective functions for a single waveform and a group of waveforms were presented. The optimized single waveform with low autocorrelation sidelobe values can reduce false alarm number and the difficulty of target decision. When multiple sonar systems work as a team, the optimized group of orthogonal waveforms with low autocorrelation sidelobe values and cross-correlation values can alleviate interferences between each other. In the simulation, the correlation performances of a single waveform and a group of orthogonal waveforms were presented, and ambiguity function showed that the designed waveforms had good velocity and distance resolution, which means that the optimized MSK waveforms are suitable for underwater detection.

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Shin, Jong-Woo, Wan-Jin Kim, Dae-Won Do, Dong-Hun Lee und Hyoung-Nam Kim. „Fast Wideband Active Detection and Doppler Estimation Using the Extended Replica of an HFM Pulse in Active SONAR Systems“. Journal of the Institute of Electronics and Information Engineers 51, Nr. 8 (25.08.2014): 11–19. http://dx.doi.org/10.5573/ieie.2014.51.8.011.

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Morisset, Dominique. „On the use of active low‐frequency sonar systems for the monitoring of littoral environment“. Journal of the Acoustical Society of America 105, Nr. 2 (Februar 1999): 1322. http://dx.doi.org/10.1121/1.426194.

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Buskenes, Jo Inge, Jon Petter Åsen, Carl-Inge C. Nilsen und Andreas Austeng. „Adapting the minimum variance beamformer to a graphics processing unit for active sonar imaging systems“. Journal of the Acoustical Society of America 133, Nr. 5 (Mai 2013): 3613. http://dx.doi.org/10.1121/1.4806739.

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Lee, Seungwoo, Iksu Seo, Jongwon Seok, Yunsu Kim und Dong Seog Han. „Active Sonar Target Classification with Power-Normalized Cepstral Coefficients and Convolutional Neural Network“. Applied Sciences 10, Nr. 23 (26.11.2020): 8450. http://dx.doi.org/10.3390/app10238450.

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Detection and classification of unidentified underwater targets maneuvering in complex underwater environments are critical for active sonar systems. In previous studies, many detection methods were applied to separate targets from the clutter using signals that exceed a preset threshold determined by the sonar console operator. This is because the high signal-to-noise ratio target has enough feature vector components to separate. However, in a real environment, the signal-to-noise ratio of the received target does not always exceed the threshold. Therefore, a target detection algorithm for various target signal-to-noise ratio environments is required; strong clutter energy can lead to false detection, while weak target signals reduce the probability of detection. It also uses long pulse repetition intervals for long-range detection and high ambient noise, requiring classification processing for each ping without accumulating pings. In this study, a target classification algorithm is proposed that can be applied to signals in real underwater environments above the noise level without a threshold set by the sonar console operator, and the classification performance of the algorithm is verified. The active sonar for long-range target detection has low-resolution data; thus, feature vector extraction algorithms are required. Feature vectors are extracted from the experimental data using Power-Normalized Cepstral Coefficients for target classification. Feature vectors are also extracted with Mel-Frequency Cepstral Coefficients and compared with the proposed algorithm. A convolutional neural network was employed as the classifier. In addition, the proposed algorithm is to be compared with the result of target classification using a spectrogram and convolutional neural network. Experimental data were obtained using a hull-mounted active sonar system operating on a Korean naval ship in the East Sea of South Korea and a real maneuvering underwater target. From the experimental data with 29 pings, we extracted 361 target and 3351 clutter data. It is difficult to collect real underwater target data from the real sea environment. Therefore, the number of target data was increased using the data augmentation technique. Eighty percent of the data was used for training and the rest was used for testing. Accuracy value curves and classification rate tables are presented for performance analysis and discussion. Results showed that the proposed algorithm has a higher classification rate than Mel-Frequency Cepstral Coefficients without affecting the target classification by the signal level. Additionally, the obtained results showed that target classification is possible within one ping data without any ping accumulation.

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George, Jomon, P. Sinchu, K. Ajith Kumar und T. Santhana Krishnan. „Towed Acoustic Countermeasures for Defending Acoustic Homing Torpedoes“. Defence Science Journal 69, Nr. 6 (16.12.2019): 607–12. http://dx.doi.org/10.14429/dsj.69.13337.

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The growing torpedo threat to ships and submarines demands effective countermeasures for defence. Detection, classification and localisation of an attacking torpedo is the first step towards launching effective countermeasures. Studies are on the rise to use the existing sonar systems to detect torpedoes and subsequently use countermeasures. The use of towed array sonar systems for torpedo detection and acoustic counter measures are the most recent and not reported much in open literature. This paper presents a modular acoustic counter measure approach using towed decoy against acoustic homing torpedoes. Describes the technologies and algorithms required for different modes of towed decoy, which is effective against both active and passive acoustic homing torpedoes. Towed decoy signal generation schemes and their realisation using digital signal processing hardware are outlined in this paper.

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Seo, Iksu, Seongweon Kim, Youngwoo Ryu, Jungyong Park und Dong Seog Han. „Underwater Moving Target Classification Using Multilayer Processing of Active Sonar System“. Applied Sciences 9, Nr. 21 (30.10.2019): 4617. http://dx.doi.org/10.3390/app9214617.

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The task of detecting and classifying highly maneuverable and unidentified underwater targets in complex environments is significant in active sonar systems. Previous studies have applied many detection schemes to this task using signals above a preset threshold to separate targets from clutter; this is because a high signal-to-noise ratio (SNR) target has sufficient feature vector components to be separated out. However, in real environments, the received target return’s SNR is not always above the threshold. Therefore, a target detection algorithm is needed for varied target SNR conditions. When the clutter energy is too strong, false detection can occur, and the probability of detection is reduced due to the weak target signature. Furthermore, since a long pulse repetition interval is used for long-range detection and ambient noise tends to be high, classification processing for each ping is needed. This paper proposes a multilayer classification algorithm applicable to all signals in real underwater environments above the noise level without thresholding and verifies the algorithm’s classification performance. We obtained a variety of experimental data by using a real underwater target and a hull-mounted active sonar system operated on Korean naval ships in the East Sea, Korea. The detection performance of the proposed algorithm was evaluated in terms of the classification rate and false alarm rate as a function of the SNR. Since experimental environment data, including the sea state, target maneuvering patterns, and sound speed, were available, we selected 1123 instances of ping data from the target over all experiments and randomly selected 1000 clutters based on the distribution of clutters for each ping. A support vector machine was employed as the classifier, and 80% of the data were selected for training, leaving the remaining data for testing. This process was carried out 1000 times. For the performance analysis and discussions, samples of scatter diagrams and feature characteristics are shown and classification tables and receiver operation characteristic (ROC) curves are presented. The results show that the proposed algorithm is effective under a variety of target strengths and ambient noise levels.

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Lokourezos, G. „Prolog To Implementation Of Adaptive And Synthetic-aperture Processing Schemes In Integrated Active-passive Sonar Systems“. Proceedings of the IEEE 86, Nr. 2 (Februar 1998): 356–57. http://dx.doi.org/10.1109/jproc.1998.659490.

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Fromm, David M. „Applying broadband beam‐based decomposition of the time reversal operator (BBDORT) to midfrequency active sonar systems“. Journal of the Acoustical Society of America 120, Nr. 5 (November 2006): 3140. http://dx.doi.org/10.1121/1.4787760.

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Lenin, K. „SUPERLATIVE ALGORITHM FOR REDUCTION OF ACTIVE POWER LOSS“. International Journal of Research -GRANTHAALAYAH 5, Nr. 10 (31.10.2017): 101–11. http://dx.doi.org/10.29121/granthaalayah.v5.i10.2017.2287.

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This paper proposes Spinner Dolphin Algorithm (SDA) for solving optimal reactive power problem. Echolocation is the genetic sonar used by Spinner dolphin & it used by few kinds of other animals for direction-finding, hunting in diverse environments. This ability of Spinner dolphin is imitated in this paper to develop a new-fangled procedure for solving optimal reactive power problem. Spinner Dolphin Algorithm (SDA) takes reward of the overriding rules and outperforms many vigorous optimization methods. The new-fangled approach SDA leads to exceptional results with small computational efforts. In order to evaluate the efficiency of the proposed algorithm, it has been tested Standard IEEE 57,118 bus systems and compared to other specified algorithms. Simulation result show that Spinner Dolphin Algorithm (SDA) is advanced to other algorithms in reducing the real power loss and voltage profiles are within the limits

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Sun, Dajun, Zixuan Jia, Tingting Teng und Cong Huang. „Strong coherent interference suppression based on second- order cone null steering beamforming“. MATEC Web of Conferences 283 (2019): 07004. http://dx.doi.org/10.1051/matecconf/201928307004.

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For active sonar systems, coherent interference, such as direct-path wave and strong multi-path, will shield the weak target echo signal, which is one of the main factors affecting the target detection performance. Null steering beamforming is an important signal processing method that suppresses strong interference. In this paper, the second-order cone programming (SOCP) method is used to perform null steering beamforming on the uniform linear array. Beam null is caused in the direction of interference to suppress strong coherent interference in the active sonar system during detection. However, there are two limitations that can causes decline of the algorithm performance. A norm-control method is proposed to limit the response near the end-fire direction of linear array, and an array manifold compensation method is introduced to solve the array manifold mismatch. Simulated and experimental data was used to evaluate the performance and verify the feasibility of the methods.

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Li, Nansong, Minghui Zhang und Bo Gao. „Horizontal Correlation of Long-Range Bottom Reverberation in Shallow Sloping Seabed“. Journal of Marine Science and Engineering 9, Nr. 4 (13.04.2021): 414. http://dx.doi.org/10.3390/jmse9040414.

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The performance of active sonar detection systems is seriously affected by the reverberation at the bottom of the waveguide in shallow water. In order to improve the performance of active sonar detection, it is necessary to understand the horizontal correlation of shallow-water bottom reverberation in active towed-array processing technology. However, the current research on the spatial correlation of reverberation is mainly based on vertical correlation, little work has been done on the horizontal correlation characteristics of long-distance seabed reverberation, and there is no support from sea test data. In this paper, the coupled mode reverberation model is applied to the horizontal correlation, and is studied according to the receiving position, time, and frequency. The simulation results show that, for the long-range bottom reverberation, the lateral correlation is greater than the longitudinal correlation in the horizontal space. By introducing the adiabatic mode solution, the mathematical model of horizontal correlation in the range-dependent waveguide with depth is derived. The numerical results show that the influence of the seabed dip angle on the horizontal correlation should be considered and that the horizontal correlation is affected obviously by the propagation effects of the sloped sea floor. Finally, the experimental data processing and analysis are given and verify the correctness of the algorithm.

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Kim, Jae-Yong, Suk-Yoon Hong, Byung-Gu Cho, Jee-Hun Song und Hyun-Wung Kwon. „Development of acoustic target strength near-field equation for underwater vehicles“. Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 233, Nr. 3 (07.06.2018): 714–21. http://dx.doi.org/10.1177/1475090218779292.

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For modern weapon systems, the most important factor in survivability is detection capability. Acoustic target strength is a major parameter of the active sonar equation. The traditional target strength equation used to predict the re-radiated intensity for the far field is derived with a plane-wave assumption. In this study, a near-field target strength equation was derived without a plane-wave assumption for a polygonal plate. The target strength equation for polygonal plates, which is applicable to the near field, is provided by the Helmholtz–Kirchhoff formula that is used as the primary equation for solving the re-radiated pressure field. A generalized definition of the sonar cross section is suggested that is applicable to the near field. In comparison experiments for a cylinder, the target strength equation for polygonal plates in near field was executed to verify the validity and accuracy of the analysis. In addition, an underwater vehicle model was analyzed with the developed near-field equation to confirm various parameter effects such as distance and frequency.

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Proksch, Roger, und Sergei Kalinin. „Piezoresponse Force Microscopy“. Microscopy Today 17, Nr. 6 (November 2009): 10–15. http://dx.doi.org/10.1017/s1551929509990988.

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Coupling between electrical and mechanical phenomena is an important feature of functional inorganic materials and biological systems alike. The applications of electromechanically active materials include sonar, ultrasonic and medical imaging, sensors, actuators, and energy-harvesting technologies, as well as non-volatile computer memories. Electromechanical coupling in electromotor proteins and cellular membranes is the universal basis for biological functionalities from hearing to cardiac activity. The future will undoubtedly see the emergence of broad arrays of piezoelectric, biological, and molecular-based electromechanical systems to allow mankind the capability not only to “think” but also “act” on the nanoscale. The need for probing electromechanical functionalities has led to the development of Piezoresponse Force Microscopy (PFM) as a tool for local nanoscale imaging (Figures 1 and 2), spectroscopy, and manipulation of piezoelectric and ferroelectric materials.

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Liu, Dali, Haoran Qu, Wei Wang und Jijie Deng. „Multiple Targets Detection of Linear Frequency-Modulated Continuous Wave Active Sonar Using Fractional Fourier Transform“. Integrated Ferroelectrics 209, Nr. 1 (01.07.2020): 1–10. http://dx.doi.org/10.1080/10584587.2020.1728798.

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Fan, Kuan, Chao Sun, Xionghou Liu und Guangyu Jiang. „MIMO Sonar DOA Estimation with Joint Matched-Filtering Based on Transmission Diversity Smoothing“. Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, Nr. 1 (Februar 2020): 6–13. http://dx.doi.org/10.1051/jnwpu/20203810006.

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There is a class of methods based on transmission diversity smoothing by multiple-input multiple-output(MIMO) sonar called MIMO-TDS which is considered as one of the most effective methods for estimation of direction-of-arrival(DOA) using MIMO sonar systems. MIMO-TDS produced by orthogonal signal transmission for active sonar can be immediately implemented with high resolution algorithms such as MVDR to estimate the direction of received signals. However, the orthogonal transmission mode of MIMO-TDS is doomed to a loss of transmission array gain indirectly leading to the problem that the echoes are not equipped with as high SNR as enough for an accurate target localization, especially in scenarios in which the targets are far away from array. In order to solving the "low SNR" problem, a solution using all transmitted signals simultaneously to design a joint matched-filter intended for received signal is proposed to improve the performance of MIMO-TDS, which is inspired by the match-filtering concept of "MIMO sonar virtual array method" simplified as MIMO-VA. And accordingly, the unit impulse response function of proposed joint matched-filter is the equivalent of linear sum of all orthogonal transmitted signals and the modified MIMO-TDS is named as "joint matched-filtering MIMO sonar transmission diversity smoothing DOA estimation method", which could be simplified as MIMO-TDS-MF. The characteristic of proposed method is analyzed theoretically and compared to MIMO-TDS and MIMO-VA in this paper:Compared with MIMO-TDS, the proposed method not only retains the advantage of transmission diversity smoothing but also improves the SNR by joint match-filtering; What's more, compared with MIMO-VA, MIMO-TDS-MF is equipped with substantially less computation than the former due to an employment of much fewer matched-filters and is in possession of a superior robustness to that of MIMO-VA. Numerical experiments demonstrate the efficiency of proposed MIMO-TDS-MF.

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DAWADEE, AAKASH, JAVAAN CHAHL, D(NANDA) NANDAGOPAL und ZORICA NEDIC. „ILLUMINATION, SCALE AND ROTATION INVARIANT ALGORITHM FOR VISION-BASED UAV NAVIGATION“. International Journal of Pattern Recognition and Artificial Intelligence 27, Nr. 05 (August 2013): 1359003. http://dx.doi.org/10.1142/s0218001413590039.

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Navigation has been a major challenge for the successful operation of an autonomous aircraft. Although success has been achieved using active methods such as radar, sonar, lidar and the global positioning system (GPS), such methods are not always suitable due to their susceptibility to jamming and outages. Vision, as a passive navigation method, is considered as an excellent alternative; however, the development of vision-based autonomous systems for outdoor environments has proven difficult. For flying systems, this is compounded by the additional challenges posed by environmental and atmospheric conditions. In this paper, we present a novel passive vision-based algorithm which is invariant to illumination, scale and rotation. We use a three stage landmark recognition algorithm and an algorithm for waypoint matching. Our algorithms have been tested in both synthetic and real-world outdoor environments demonstrating overall good performance. We further compare our feature matching method with the speed-up robust features (SURF) method with results demonstrating that our method outperforms the SURF method in feature matching as well as computational cost.

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Tompkins, Ron, und Stéphane Jespers. „Project 20 Low-Frequency Active Sonar: The Successful Union of Oceanographic and Systems R&D Disciplines at the NATO Undersea Research Centre and Elsewhere“. Oceanography 21, Nr. 2 (01.06.2008): 34–37. http://dx.doi.org/10.5670/oceanog.2008.50.

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Nancekievill, Matthew, Jose Espinosa, Simon Watson, Barry Lennox, Ashley Jones, Malcolm J. Joyce, Jun-ichi Katakura et al. „Detection of Simulated Fukushima Daichii Fuel Debris Using a Remotely Operated Vehicle at the Naraha Test Facility“. Sensors 19, Nr. 20 (22.10.2019): 4602. http://dx.doi.org/10.3390/s19204602.

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The use of robotics in harsh environments, such as nuclear decommissioning, has increased in recent years. Environments such as the Fukushima Daiichi accident site from 2011 and the Sellafield legacy ponds highlight the need for robotic systems capable of deployment in hazardous environments unsafe for human workers. To characterise these environments, it is important to develop robust and accurate localization systems that can be combined with mapping techniques to create 3D reconstructions of the unknown environment. This paper describes the development and experimental verification of a localization system for an underwater robot, which enabled the collection of sonar data to create 3D images of submerged simulated fuel debris. The system was demonstrated at the Naraha test facility, Fukushima prefecture, Japan. Using a camera with a bird’s-eye view of the simulated primary containment vessel, the 3D position and attitude of the robot was obtained using coloured LED markers (active markers) on the robot, landmarks on the test-rig (passive markers), and a depth sensor on the robot. The successful reconstruction of a 3D image has been created through use of a robot operating system (ROS) node in real-time.

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Amichai, Eran, Gaddi Blumrosen und Yossi Yovel. „Calling louder and longer: how bats use biosonar under severe acoustic interference from other bats“. Proceedings of the Royal Society B: Biological Sciences 282, Nr. 1821 (22.12.2015): 20152064. http://dx.doi.org/10.1098/rspb.2015.2064.

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Active-sensing systems such as echolocation provide animals with distinct advantages in dark environments. For social animals, however, like many bat species, active sensing can present problems as well: when many individuals emit bio-sonar calls simultaneously, detecting and recognizing the faint echoes generated by one's own calls amid the general cacophony of the group becomes challenging. This problem is often termed ‘jamming’ and bats have been hypothesized to solve it by shifting the spectral content of their calls to decrease the overlap with the jamming signals. We tested bats’ response in situations of extreme interference, mimicking a high density of bats. We played-back bat echolocation calls from multiple speakers, to jam flying Pipistrellus kuhlii bats, simulating a naturally occurring situation of many bats flying in proximity. We examined behavioural and echolocation parameters during search phase and target approach. Under severe interference, bats emitted calls of higher intensity and longer duration, and called more often. Slight spectral shifts were observed but they did not decrease the spectral overlap with jamming signals. We also found that pre-existing inter-individual spectral differences could allow self-call recognition. Results suggest that the bats’ response aimed to increase the signal-to-noise ratio and not to avoid spectral overlap.

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Kounitsky, Pavel, Jens Rydell, Eran Amichai, Arjan Boonman, Ofri Eitan, Anthony J. Weiss und Yossi Yovel. „Bats adjust their mouth gape to zoom their biosonar field of view“. Proceedings of the National Academy of Sciences 112, Nr. 21 (04.05.2015): 6724–29. http://dx.doi.org/10.1073/pnas.1422843112.

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Active sensing, where sensory acquisition is actively modulated, is an inherent component of almost all sensory systems. Echolocating bats are a prime example of active sensing. They can rapidly adjust many of their biosonar parameters to optimize sensory acquisition. They dynamically adjust pulse design, pulse duration, and pulse rate within dozens of milliseconds according to the sensory information that is required for the task that they are performing. The least studied and least understood degree of freedom in echolocation is emission beamforming—the ability to change the shape of the sonar sound beam in a functional way. Such an ability could have a great impact on the bat’s control over its sensory perception. On the one hand, the bat could direct more energy into a narrow sector to zoom its biosonar field of view, and on the other hand, it could widen the beam to increase the space that it senses. We show that freely behaving bats constantly control their biosonar field of view in natural situations by rapidly adjusting their emitter aperture—the mouth gape. The bats dramatically narrowed the beam when entering a confined space, and they dramatically widened it within dozens of milliseconds when flying toward open space. Hence, mouth-emitting bats dynamically adjust their mouth gape to optimize the area that they sense with their echolocation system.

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Gu, Boxuan, Yaowu Chen, Rongxin Jiang und Xuesong Liu. „Optimization of Sparse Cross Array Synthesis via Perturbed Convex Optimization“. Sensors 20, Nr. 17 (31.08.2020): 4929. http://dx.doi.org/10.3390/s20174929.

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Three-dimensional (3-D) imaging sonar systems require large planar arrays, which incur hardware costs. In contrast, a cross array consisting of two perpendicular linear arrays can also support 3-D imaging while dramatically reducing the number of sensors. Moreover, the use of an aperiodic sparse array can further reduce the number of sensors efficiently. In this paper, an optimized method for sparse cross array synthesis is proposed. First, the beamforming of a cross array based on a multi-frequency algorithm is simplified for both near-field and far-field. Next, a perturbed convex optimization algorithm is proposed for sparse cross array synthesis. The method based on convex optimization utilizes a first-order Taylor expansion to create position perturbations that can optimize the beam pattern and minimize the number of active sensors. Finally, a cross array with 100 + 100 sensors is employed from which a sparse cross array with 45 + 45 sensors is obtained via the proposed method. The experimental results show that the proposed method is more effective than existing methods for obtaining optimum results for sparse cross array synthesis in both the near-field and far-field.

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Fernandez, Vicente I., Audrey Maertens, Frank M. Yaul, Jason Dahl, Jeffrey H. Lang und Michael S. Triantafyllou. „Lateral-Line-Inspired Sensor Arrays for Navigation and Object Identification“. Marine Technology Society Journal 45, Nr. 4 (01.07.2011): 130–46. http://dx.doi.org/10.4031/mtsj.45.4.20.

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AbstractThe lateral line is a critical component of fish sensory systems, found to affect numerous aspects of behavior, including maneuvering in complex fluid environments with poor visibility. This sensory organ has no analog in modern ocean vehicles, despite its utility and ubiquity in nature, and could fill the gap left by sonar and vision systems in turbid, cluttered environments.To emulate the lateral line and characterize its object-tracking and shape recognition capabilities, a linear array of pressure sensors is used along with analytic models of the fluid in order to determine position, shape, and size of various objects in both passive and active sensing schemes. We find that based on pressure information, tracking a moving cylinder can be effectively achieved via a particle filter. Using principal component analysis, we are also able to reliably distinguish between cylinders of different cross section and identify the critical flow signature information that leads to the shape identification. In a second application, we employ pressure measurements on an artificial fish and an unscented Kalman filter to successfully identify the shape of an arbitrary static cylinder.Based on the experiments, we conclude that a linear pressure sensor array for identifying small objects should have a sensor-to-sensor spacing of less than 0.03 (relative to the length of the sensing body) and resolve pressure differences of at least 10 Pa. These criteria are used in the development of an artificial lateral line adaptable to the curved hull of an underwater vehicle, employing conductive polymer technologies to form a flexible array of small pressure sensors.

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Seo. „Single Ping Clutter Reduction Algorithm Using Statistical Features of Peak Signal to Improve Detection in Active Sonar System“. Journal of the Acoustical Society of Korea 34, Nr. 1 (2015): 75. http://dx.doi.org/10.7776/ask.2015.34.1.075.

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Dalhoff, Finn, Lotte M. Larsen, Jon R. Ineson, Svend Stouge, Jørgen A. Bojesen-Koefoed, Susanne Lassen, Antoon Kuijpers, Jan A. Rasmussen und Henrik Nøhr-Hansen. „Continental crust in the Davis Strait: new evidence from seabed sampling“. Geological Survey of Denmark and Greenland (GEUS) Bulletin 10 (29.11.2006): 33–36. http://dx.doi.org/10.34194/geusb.v10.4901.

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Although the structural framework of the subsurface offshore West Greenland has been well documented based on comprehensive seismic analysis (cf. Dalhoff et al. 2003), the stratigraphy of the region is less well known. The oldest documented sedimentary rocks drilled offshore West Greenland are Santonian sandstones reached at TD in the 6354/4-1 well (Fig. 1) although reworked palynomorphs of Carboniferous, Triassic and Jurassic (Kimmeridgian) age have been reported from a number of wells in the region. In order to obtain better constraints on the pre-Upper Cretaceous stratigraphy, a preliminary screening was undertaken to identify inversion structures and erosional canyons where such deeper stratigraphic levels crop out at the seabed (Nielsen et al. 2001). Sea-floor sampling at selected sites between 62° and 67°N (Fig. 1) was undertaken during the summers of 2003 and 2004. Other objectives of these cruises were to seek direct evidence of active petroleum systems, to establish further constraints on tectonic and stratigraphic models, and to obtain a better understanding of the Neogene and Pleistocene history of the region (Dalhoff et al. 2005). The most promising seabed features identified by Nielsen etal.(2001) were investigated in more detail using a wide range of techniques in order to optimise sampling positions. In 2003, these techniques included echo sounder, side-scan sonar, singlechannel seismic and video inspection before sampling either by dredge, gravity corer, or by video-controlled grab. In 2004, comprehensive data acquisition with a deep-water sparker system was undertaken before sampling by dredge or gravity corer, supplemented by grab samples at selected stations.

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Norris, LeAnn, Zaina Qureshi, Sara Barnato, Stephen Lai und Charles Bennett. „Serious Adverse Drug Reactions (sADRS) Associated with Hematopoietic Growth Factors: A Systematic Review From the Southern Network on Adverse Reactions (SONAR) Program“. Blood 116, Nr. 21 (19.11.2010): 2555. http://dx.doi.org/10.1182/blood.v116.21.2555.2555.

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Abstract Abstract 2555 Erythrpoiesis stimulating agents (ESAs) and the granulocyte hematopoietic growth factors granulocyte colony stimulating factor (G-CSF) and pegylated G-CSF revolutionized supportive care approaches to anemia and neutropenia, respectively. Thrombopoietin-receptor agonists improve antibody-mediated thrombocytopenia management. For these drugs, as with all agents, a comprehensive understanding of sADRs is important, however, often difficult to do. We reviewed sADRS described in meta-analyses and web-site materials maintained by regulatory agencies and manufacturers reports (1989 to July 2010; n=2,094). Overall, 28 systematic reviews, six package inserts, three medication guides, four FDA Risk Evaluation and Mitigation Systems (REMS) materials, 16 Summaries of Product Characteristics/Product Assessment Reports were included. For ESAs, common sADRs associated with increased relative risks (RRs) included: mortality among cancer patients with chemotherapy-associated anemia or cancer patients not receiving active treatment (RRs: 1.1–1.2); cerebrovascular and cardiovascular events among chronic kidney disease patients ((RRs: 1.3, 1.9), and venous thromboembolism in the cancer setting (RRs;16-1.7). For G-CSF/pegylated-GCSF, rare instances of myelodysplasia/acute myeloid leukemia (MDS/AML) associated with statistically increased RRs were reported among breast cancer patients receiving chemotherapy in trials reported from one NCI-sponsored clinical trials group, one meta-analysis, and one review of Medicare/SEER databases (RR: 1.9–2.1), although the absolute risks were very small (< 2 per 100,000 treated patients). Other rarely reported sADRs (total N < 20) included splenic rupture following G-CSF stimulation of healthy peripheral blood stem donors. Bone marrow fibrosis and collagen deposition were reported with thrombopoietin receptor agonists, although the implications of this finding is uncertain. Also, instances of VTEs were reported among persons who developed high platelet counts following administration of these thrombopoeitin receptor agonists. SADRs are commonly associated with ESA administration in a range of settings, are uncommon occurrences with G-CSF/pegylated G-CSF, and are not well characterized for thrombopoieitin receptor agonists. Formal pharmacovigilance initiatives are ongoing, including FDA mandated REMS with restricted distribution requirement for ESAs in the cancer setting (APPRISE) and the NEXUS and the PROMACTA CARES programs for thrombopoeitin receptor agonists. ESAs (Cancer) ESAs (CKD) G-CSF/Pegylated G-CSF VTE Mortality Cerebrovascular and CVD AML/MDS RR 1.57 and 1.67 1.10 to 1.17 1.34 and 1.92 2.14 and 1.92 95% CI 1.31–1.87 and 1.35–2.06 1.02–1.20 and 1.06–1.30 1.03–1.74 and 1.38–2.26 1.12–4.08 and 1.19–3.07 Baseline Risk Absolute Risk Common Common Common Rare (2/100,000) Disclosures: Bennett: Pfizer: Consultancy.

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O’Brien, G. W., K. Glenn, G. Lawrence, A. K. Williams, M. Webster, S. Burns und R. Cowley. „INFLUENCE OF HYDROCARBON MIGRATION AND SEEPAGE ON BENTHIC COMMUNITIES IN THE TIMOR SEA, AUSTRALIA“. APPEA Journal 42, Nr. 1 (2002): 225. http://dx.doi.org/10.1071/aj01013.

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The Ashmore Platform–Timor Sea region of Australia’s North West Shelf is an area of significant petroleum exploration potential, with several large commercial oil fields present. Moreover, exploration activity seems likely to continue at current levels for the foreseeable future, and may also extend into deeper water, given high oil prices and improved drilling technologies. The area is also one of high conservation value, with both the Cartier Marine reserve and Ashmore Reef (a Category 1 marine park), as well as numerous other genetically-rich carbonate seed bank systems, closely associated spatially with exploration activities. Balancing the conservation and resource values in this area will present a key challenge into the future.The magnitude of this challenge has been highlighted by recent work undertaken by AGSO, which involved the acquisition and interpretation of assorted remote sensing data, such as high-resolution bathymetry (including sidescan sonar), satellite synthetic aperture radar (SAR), Landsat, water column geochemical sniffer, airborne laser fluorosensor, seismic data and seafloor sediment sampling. These studies have shown that, at both a regional and local scale, the development of these important carbonate systems appears to directly relate to the geological development of the area.At a regional scale, the collision between the Australian and Eurasian crustal plates in the Pliocene (At a local scale, new data also strongly suggest that the locations of the majority of reefs and carbonate banks and build-ups in the area are associated with active and palaeo-hydrocarbon seeps. These seeps are localised over either fault systems which tap the reservoir, along migration fairways, or at the pinch-out of the regional Cretaceous top seal. Our interpretations suggest that the reefs and the build-ups formed by a sequential process. Firstly, hydrocarbon seepage (induced by collisionrelated faulting) localised small seafloor (chemolithotrophic) biological carbonate communities, which ultimately formed topographically positive features. These higher relief features were subsequently preferentially colonised by an assortment of reef-building biota, whose rapid growth progressively kept up with rising sea-level (which was driven principally by collisionrelated subsidence). The most favourable conditions for initial reef colonisation probably occurred during periods of relatively low sea-level, when the areas around the reefs were located at much shallower water depths (Clearly, the fact that the genetically rich carbonate communities in this area are probably causally related to natural hydrocarbon seepage (and the attendant processes which drove that seepage) will present a series of almost unique exploration, development (especially engineering) and conservation challenges.

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Jin, Meng, Yuqi Bai, Emmanuel Devys und Liping Di. „Toward a Standardized Encoding of Remote Sensing Geo-Positioning Sensor Models“. Remote Sensing 12, Nr. 9 (11.05.2020): 1530. http://dx.doi.org/10.3390/rs12091530.

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Geolocation information is an important feature of remote sensing image data that is captured through a variety of passive or active observation sensors, such as push-broom electro-optical sensor, synthetic aperture radar (SAR), light detection and ranging (LIDAR) and sound navigation and ranging (SONAR). As a fundamental processing step to locate an image, geo-positioning is used to determine the ground coordinates of an object from image coordinates. A variety of sensor models have been created to describe geo-positioning process. In particular, Open Geospatial Consortium (OGC) has defined the Sensor Model Language (SensorML) specification in its Sensor Web Enablement (SWE) initiative to describe sensors including the geo-positioning process. It has been realized using syntax from the extensible markup language (XML). Besides, two standards defined by the International Organization for Standardization (ISO), ISO 19130-1 and ISO 19130-2, introduced a physical sensor model, a true replacement model, and a correspondence model for the geo-positioning process. However, a standardized encoding for geo-positioning sensor models is still missing for the remote sensing community. Thus, the interoperability of remote sensing data between application systems cannot be ensured. In this paper, a standardized encoding of remote sensing geo-positioning sensor models is introduced. It is semantically based on ISO 19130-1 and ISO 19130-2, and syntactically based on OGC SensorML. It defines a cross mapping of the sensor models defined in ISO 19130-1 and ISO 19130-2 to the SensorML, and then proposes a detailed encoding method to finalize the XML schema (an XML schema here is the structure to define an XML document), which will become a profile of OGC SensorML. It seamlessly unifies the sensor models defined in ISO 19130-1, ISO 19130-2, and OGC SensorML. By enabling a standardized description of sensor models used to produce remote sensing data, this standard is very promising in promoting data interoperability, mobility, and integration in the remote sensing domain.

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