• Title/Summary/Keyword: energy detection

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Study on the neutron imaging detector with high spatial resolution at China spallation neutron source

  • Jiang, Xingfen;Xiu, Qinglei;Zhou, Jianrong;Yang, Jianqing;Tan, Jinhao;Yang, Wenqin;Zhang, Lianjun;Xia, Yuanguang;Zhou, Xiaojuan;Zhou, Jianjin;Zhu, Lin;Teng, Haiyun;Yang, Gui-an;Song, Yushou;Sun, Zhijia;Chen, Yuanbo
    • Nuclear Engineering and Technology
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    • v.53 no.6
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    • pp.1942-1946
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    • 2021
  • Gadolinium oxysulfide (GOS) is regarded as a novel scintillator for the realization of ultra-high spatial resolution in neutron imaging. Monte Carlo simulations of GOS scintillator show that the capability of its spatial resolution is towards the micron level. Through the time-of-flight method, the light output of a GOS scintillator was measured to be 217 photons per captured neutron, ~100 times lower than that of a ZnS/LiF:Ag scintillator. A detector prototype has been developed to evaluate the imaging solution with the GOS scintillator by neutron beam tests. The measured spatial resolution is ~36 ㎛ (28 line pairs/mm) at the modulation transfer function (MTF) of 10%, mainly limited by the low experimental collimation ratio of the beamline. The weak light output of the GOS scintillator requires an enormous increase in the neutron flux to reduce the exposure time for practical applications.

Adaptive Energy Detection for Spectrum Sensing in Cognitive Radio (인지 무선 시스템에서 스펙트럼 감지를 위한 적응 에너지 검파)

  • Lim, Chang-Heon
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.8
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    • pp.42-46
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    • 2010
  • Energy detection based spectrum sensing compares the energy of a received signal from a primary user with a detection threshold and decides whether it is active or not in the frequency band of interest. Here the detection threshold depends on not only a target false alarm probability but also the level of the noise energy in the band. So, if the noise energy changes, the detection threshold must be adjusted accordingly to maintain the given false alarm probability. Most previous works on energy detection for spectrum sensing are based on the assumption that noise energy is known a priori. In this paper, we present a new energy detection scheme updating its detection threshold under the assumption that the noise is white, and analyze its detection performance. Analytic results show that the proposed scheme can maintain a target false alarm rate without regard to the noise energy level and its spectrum sensing performance gets better as the time bandwidth product of the signal used to estimate the noise energy increases.

Research Infrastructure Foundation for Core-technology Incubation of Radiation Detection System

  • Kim, Han Soo;Ha, Jang Ho;Kim, Young Soo;Cha, Hyung Ki
    • Journal of Radiation Industry
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    • v.6 no.1
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    • pp.67-73
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    • 2012
  • The development of radiation detection systems mainly consist of two parts-radiation detector fabrication including material development, and its appropriate electronics development. For the core-technology incubation of a radiation detection system, radiation fabrication and an evaluation facility are scheduled to be founded at the RFT (Radiation Fusion Technology) Center at KAERI (Korea Atomic Energy Research Institute) by 2015. This facility is utilized for the development and incubation of bottleneck-technologies to accelerate the industrialization of a radiation detection system in the industrial, medical, and radiation security fields. This facility is also utilized for researchers to develop next-generation radiation detection instruments. In this paper, the establishment of core-technology development is introduced and its technological mission is addressed.

Receiving Signal Level Measurement Based Weighting Method for Broadband Energy Detection (광대역 에너지 탐지를 위한 수신신호 강도 크기기반 가중치인가 기법)

  • Kang, TaeSu;Kim, Youngshin;Kim, Yong Guk;Moon, Sang-Taeck
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.6
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    • pp.532-540
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    • 2013
  • In this paper, we propose the modified SED (Subband Energy Detection) which can assign weights adapting to the receiving signal level for the broadband energy detection in the passive SONARs. SED which is one of the broadband processing mainly employed by passive SONARs to detect a target is more robust against interference like multi signals or a clutter than CED (Conventional Energy Detection), but it degrades detection performance to assign weights independent of extracted extrema level of the receiving signal. Therefore, in this paper, the weighting method which can efficiently assigns rewards or penalties adapting to extracted extrema level of the receiving signal is proposed. In order to evaluate the performance of proposed method, we conducted experiments by using simulation and real ocean acoustic signal which is acquired from Yellow Sea. From the experiments, our proposed method has shown better performance than conventional SED.

Improved Genetic Algorithm-Based Damage Detection Technique Using Modal Strain Energy (모드변형에너지를 이용한 향상된 유전알고리즘 기반 손상검색기법)

  • Park Jae-Hyung;Lee Jung-Mi;Kim Jeong-Tae;Ryu Yeon-Sun
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.459-466
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    • 2006
  • The objective of this study is to improve the accuracy of damage detection using natural frequency and modal strain energy. The following approaches are used to achieve the goal. First, modal strain energy is introduced and newly GA-based damage detection technique using natural frequency and modal strain energy is proposed. Next, to verify efficiency of the proposed technique, damage scenarios for free-free beams are designed and the vibration modal tests as damage cases are conducted. Finally, feasibility of proposed technique is verified in comparison with a GA-based damage detection technique using natural frequency and mode shape.

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Effects of Noise Power Uncertainty on Energy Detection for Spectrum Sensing (잡음 전력의 불확실성이 에너지 검파 기반의 스펙트럼 감지에 미치는 영향)

  • Lim, Chang-Heon
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.48 no.11
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    • pp.22-27
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    • 2011
  • In spectrum sensing, an energy detector compares the energy of a received signal with a predetermined detection threshold and decides whether a primary user is active or not in a licensed frequency band. Here the detection threshold is related to the noise power level in the band. Most previous works on energy detection have assumed that the noise power is exactly known a priori. However, this assumption does not hold in practice since there may be some uncertainty about the noise power. So it is necessary to investigate its effects on the performance of energy detection for spectrum sensing. In this paper, we analyze the effects using the residue theorem for contour integral and present the associated numerical results.

A New Islanding Detection Method Based on Feature Recognition Technology

  • Zheng, Xinxin;Xiao, Lan;Qin, Wenwen;Zhang, Qing
    • Journal of Power Electronics
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    • v.16 no.2
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    • pp.760-768
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    • 2016
  • Three-phase grid-connected inverters are widely applied in the fields of new energy power generation, electric vehicles and so on. Islanding detection is necessary to ensure the stability and safety of such systems. In this paper, feature recognition technology is applied and a novel islanding detection method is proposed. It can identify the features of inverter systems. The theoretical values of these features are defined as codebooks. The difference between the actual value of a feature and the codebook is defined as the quantizing distortion. When islanding happens, the sum of the quantizing distortions exceeds the threshold value. Thus, islanding can be detected. The non-detection zone can be avoided by choosing reasonable features. To accelerate the speed of detection and to avoid miscalculation, an active islanding detection method based on feature recognition technology is given. Compared to the active frequency or phase drift methods, the proposed active method can reduce the distortion of grid-current when the inverter works normally. The principles of the islanding detection method based on the feature recognition technology and the improved active method are both analyzed in detail. An 18 kVA DSP-based three-phase inverter with the SVPWM control strategy has been established and tested. Simulation and experimental results verify the theoretical analysis.

Energy Detection Based Sensing for Secure Cognitive Spectrum Sharing in the Presence of Primary User Emulation Attack

  • Salem, Fatty M.;Ibrahim, Maged H.;Ibrahim, I.I.
    • IEIE Transactions on Smart Processing and Computing
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    • v.2 no.6
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    • pp.357-366
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    • 2013
  • Spectrum sensing, as a fundamental functionality of Cognitive Radio (CR), enables Secondary Users (SUs) to monitor the spectrum and detect spectrum holes that could be used. Recently, the security issues of Cognitive Radio Networks (CRNs) have attracted increasing research attention. As one of the attacks against CRNs, a Primary User Emulation (PUE) attack compromises the spectrum sensing of CR, where an attacker monopolizes the spectrum holes by impersonating the Primary User (PU) to prevent SUs from accessing the idle frequency bands. Energy detection is often used to sense the spectrum in CRNs, but the presence of PUE attack has not been considered. This study examined the effect of PUE attack on the performance of energy detection-based spectrum sensing technique. In the proposed protocol, the stationary helper nodes (HNs) are deployed in multiple stages and distributed over the coverage area of the PUs to deliver spectrum status information to the next stage of HNs and to SUs. On the other hand, the first stage of HNs is also responsible for inferring the existence of the PU based on the energy detection technique. In addition, this system provides the detection threshold under the constraints imposed on the probabilities of a miss detection and false alarm.

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An Efficient Spectrum Sensing Technique for Wireless Energy Harvesting Systems (무선에너지하비스팅 시스템을 위한 효율적인 스펙트럼 센싱 기법)

  • Hwang, Yu Min;Shin, Yoan;Kim, Dong In;Kim, Jin Young
    • Journal of Satellite, Information and Communications
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    • v.12 no.4
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    • pp.141-145
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    • 2017
  • Spectrum sensing is a critical functionality of Cognitive Radio(CR) systems and the CR systems can be applied to RF energy harvesting systems to improve an energy harvesting rate. There are number of spectrum sensing techniques. One of techniques is energy detection. Energy detection is the simplest detection method and is the most commonly used. But, energy detection has a hidden terminal problem in real wireless communication, because of secondary user (SU) can be affected by frequency fading and shadowing. Cooperative spectrum sensing can solve this problem using spatial diversity of SUs. But it has a problem of increasing data by processing multiple secondary. So, we propose the system model using adaptive spectrum sensing algorithm and system model is simulated. This algorithm chooses sensing method between single energy sensing and cooperative energy according to the received signal's Signal to Noise Ratio (SNR) from Primary User (PU). The simulation result shows that adaptive spectrum sensing has an efficiency and improvement in CR systems.