Security Inspection Research Articles

Amplitude and phase imaging using incoherent free-running self-oscillating device in millimeter- and terahertz-wave bands

To improve the accuracy of material identification in millimeter- and terahertz-wave nondestructive imaging during security and other inspections, it is important to perform both amplitude and phase imaging. Highly coherent sources generated based on the frequency multiplication of stable microwave sources are promising for these applications. However, this method reduces the fidelity of the image due to the interference phenomenon with reflected waves on the sample surface. In this paper, we propose and demonstrate amplitude and phase imaging using an incoherent free-running self-oscillating device. We used a Gunn oscillator operating at 122.5 GHz as a millimeter-wave source and a photoconductive antenna as a detector. The frequency and phase noise of the source are canceled by the low-frequency electronics, which realize phase imaging using an incoherent source. We performed amplitude and phase imaging on low-loss polypropylene objects and obtained ∼22 times higher imaging contrast in the latter than in the former. Furthermore, we were able to obtain high-fidelity imaging results with less interference in both amplitude and phase imaging. The proposed system is reliable and inexpensive because the source operates with a DC power source only, and the frequency and phase noise-cancellation electronics consist of low-frequency circuits. Moreover, because the noise-cancellation electronics are independent of the RF frequency, the system is easily extendible to the higher frequency region to improve its spatial resolution. This paves the way for the realization of a diode-based, sensitive, and low-cost integrated system that allows both amplitude and phase imaging for material identification in security inspections.

Passive polarimetric imaging of millimeter and terahertz waves for personnel security screening.

Passive millimeter and terahertz wave imaging is a powerful way for personnel security inspection and scene monitoring. The existing systems usually have a single polarization mode. To obtain more information, polarimetric imaging has been preliminarily explored recently. However, there is no work exhibiting high-performance polarimetric imaging to analyze and interpret polarization characteristics. In this Letter, we report on the development of a W-band passive polarimetric imaging system for human body screening and present the polarization characteristics analysis of several typical scenarios. The experimental system has a spatial resolution of better than 2 cm at 2.5 m distance and has a thermal sensitivity of better than 0.3 K. The system can display polarization properties of human bodies and concealed objects. The experimental results demonstrate that passive polarimetric imaging has a great potential for object contrast enhancement, detection, segmentation, and recognition.

Two dimensional array of MPPC and CsI(Tl) for radiation monitoring prototype

An effcient radiation and position monitoring system is useful for preliminary security inspection and radiation emergency preparedness and response. A high sensitivity and effective monitoring system is needed for these applications. In this study, two position-sensitive prototypes were proposed by using of 8 Multi Pixel Photon Counters (MPPC) and coupled to the cesium iodide with Thallium (CsI(Tl)) scintillator. This inorganic scintillator was chosen for its output wavelength compatibility with MPPC, slightly hygroscopic, high photon transmission, and input energy. For both prototypes, eight MPPCs with di_erent con_gurations were used to obtain active areas of 2.0 × 2.4 cm2 and 2.5 × 4.5cm2, respectively. The prototype has been tested with radioactive (Tl-204 and Co-60). The intensity received by each MPPC’s readout will be recorded using Extended Analogue SiPM Integrated ReadOut Chip (EASIROC) module. Our test showed that both prototypes were sensitive to both beta and gamma sources and were able to reliably determine the sources’ positions. It was shown that the first prototype had greater resolution and performance than the second prototype. This studies may help to improve radiation detection system which is suitable for homeland security, medical field and scanning system.

A Pythagorean fuzzy Petri net based security assessment model for civil aviation airport security inspection information system

This paper investigates the problem of the existing information system security situation assessment models that are less concerned about fuzzy factors and lack of reasoning. First, Pythagorean fuzzy sets are adopted to deal with the ambiguity and uncertainty of the civil aviation airport security inspection information system security situation indicators, and a Pythagorean fuzzy Petri nets (PFPNs) model is established according to the indicator system. Then, based on the characteristics of PFPN, the propositions credibility reasoning algorithm and the security situation fuzzy reasoning algorithm are designed. Finally, the feasibility of the model is verified through the assessment experiment on the security inspection information system of a civil aviation airport. The experimental results show that the PFPN model has better stability and lower algorithm time complexity compared with other models.

Reflection Removal Using Dual-Polarization and Saliency in Millimeter-Wave and Terahertz Imaging

Passive millimeter-wave and terahertz (MMW/THz) imaging is a significant technique used in personal security inspection and scene surveillance. However, a human body generally generates an obvious reflection on the floor, which may have negative influences on target detection and observer vision. In this article, we present a physically based method using dual-polarization feature and saliency information to solve the problem of reflection removal. The physical principle of a special dual-polarization phenomenon has been revealed by theoretical calculation and simulation analysis. By combining the second Stokes parameter (TQ) and modified linear polarization ratio (mLPR), a new feature parameter has been created to extract reflections of human bodies. By using a saliency analysis, the false positive alarms are eliminated completely. The experimental results demonstrate the robustness and effectiveness of the proposed method using various measured MMW/THz images.

A Study on Photoneutron Characteristics Generated from Target and Collimator of Electron Linear Accelerator for Container Security Inspection using MCNP6 Code

A Study on Photoneutron Characteristics Generated from Target and Collimator of Electron Linear Accelerator for Container Security Inspection using MCNP6 Code

Implementing a high-efficiency similarity analysis approach for firmware code.

The rapid expansion of the open-source community has shortened the software development cycle, but the spread of vulnerabilities has been accelerated, especially in the field of the Internet of Things. In recent years, the frequency of attacks against connected devices is increasing exponentially; thus, the vulnerabilities are more serious in nature. The state-of-the-art firmware security inspection technologies, such as methods based on machine learning and graph theory, find similar applications depending on the known vulnerabilities but cannot do anything without detailed information about the vulnerabilities. Moreover, model training, which is necessary for the machine learning technologies, requires a significant amount of time and data, resulting in low efficiency and poor extensibility. Aiming at the above shortcomings, a high-efficiency similarity analysis approach for firmware code is proposed in this study. First, the function control flow features and data flow features are extracted from the functions of the firmware and of the vulnerabilities, and the features are used to calculate the SimHash of the functions. The mass storage and fast query capabilities of the SimHash are implemented by the pigeonhole principle. Second, the similarity function pairs are analyzed in detail within and among the basic blocks. Within the basic blocks, the symbolic execution is used to generate the basic block semantic information, and the constraint solver is used to determine the semantic equivalence. Among the basic blocks, the local control flow graphs are analyzed to obtain their similarity. Then, we implemented a prototype and present the evaluation. The evaluation results demonstrate that the proposed approach can implement large-scale firmware function similarity analysis. It can also get the location of the real-world firmware patch without vulnerability function information. Finally, we compare our method with existing methods. The comparison results demonstrate that our method is more efficient and accurate than the Gemini and StagedMethod. More than 90% of the firmware functions can be indexed within 0.1 s, while the search time of 100,000 firmware functions is less than 2 s.

Organic phosphors with bright triplet excitons for efficient X-ray-excited luminescence

Materials that exhibit X-ray-excited luminescence have great potential in radiation detection, security inspection, biomedical applications and X-ray astronomy1–5. However, high-performance materials are almost exclusively limited to ceramic scintillators, which are typically prepared under high temperatures6. Herein we report metal-free organic phosphors based on a molecular design that supports efficient triplet exciton harvesting to enhance radioluminescence. These organic scintillators exhibit a detection limit of 33 nGy s–1, which is 167 times lower than the standard dosage for X-ray medical examination and we demonstrate their potential application in X-ray radiography. These findings provide a fundamental design principle and new route for the creation of promising alternatives to incumbent inorganic scintillators. Furthermore, they offer new opportunities for development of flexible, stretchable X-ray detectors and imagers for non-destructive radiography testing and medical imaging. Organic, metal-free materials that act as efficient X-ray scintillators could bring new opportunities for X-ray imaging.

High-Performance X-ray Detector Based on Single-Crystal β-Ga2O3:Mg.

X-ray detection plays an important role in medical imaging, scientific research, and security inspection. Recently, the β-Ga2O3 single-crystal-based X-ray detector has attracted extensive attention due to its excellent intrinsic properties such as good absorption for X-ray photons, a high breakdown electric field, high stability, and low cost. However, developing a high-performance β-Ga2O3-based X-ray detector remains a challenge because of the large dark current and the high oxygen vacancy concentration in the crystals. In this paper, we report a high-performance Mg-doped β-Ga2O3 single-crystal-based X-ray detector with a sandwich structure. The reduced dark current enables the detector to have a high sensitivity of 338.9 μC Gy-1 cm-2 under 50 keV X-ray irradiation with a dose rate of 69.5 μGy/s. The sensitivity is 16-fold higher than that of the commercial amorphous selenium detector. Furthermore, the reduced oxygen vacancy concentration can improve the response speed (<0.2 s) of the detector. The present studies provide a promising method to obtain the high performances for the X-ray detector based on β-Ga2O3 single crystals.

Design of Remote Driving Wheeled Robot

With the continuous advancement of high technology such as cloud computing, artificial intelligence, modern sensing, information fusion, communication and automatic control, the development speed of unmanned vehicles will continue to accelerate, and the acceptance and demand of unmanned, vehicles will also gradually promoted. Although unmanned vehicles have not yet been widely promoted, their applicable fields are gradually emerging. Transportation, logistics, environmental sanitation, and security inspections will be its main application areas. This project intends to design and produce an unmanned vehicle based on embedded systems and the Internet of Things, and add a machine vision system to enable it to complete the required operations in different scenarios. In order to complete the operation requirements in different scenarios, the unmanned vehicle designed in this project can realize the remote control of the car to complete forward, backward, and steering actions through a driving simulator.

Triple-Source Swinging Spiral CT Imaging Method for Security Inspection

Triple-Source Swinging Spiral CT Imaging Method for Security Inspection

New infrastructure-oriented power network security supervision innovative mechanism and system architecture

Under the framework of latest digital infrastructure, the application of emerging technologies in the power system has become more in-depth, and the security of power networks has ushered the new challenges. Facing new challenges, power network security inspectors need to keep pace with the times and make innovations in response to the new circumstances. This paper summarizes and analyses the existing network security supervision specifications and practical experience of the State Grid Corporation of China, and combines the laws, regulations, standards and corporate document requirements such as the Cyber Security Law and the Classified Protection 2.0 National Standard, based on the new network security characteristics of the new power digital infrastructure, research the innovative mechanism and system architecture of the network security supervision of power grid enterprises from the aspects of management and technology. Based on the new requirements of Classified Protection 2.0, this paper proposes a network security inspection evaluation system to help grid companies build new lines of network security.

Management of Schemes and Threat Prevention in ICS Partner Companies Security

An analysis of the recent major security incidents related to industrial control systems, revealed that most had been caused by company employees. Therefore, enterprise security management systems have been developed to focus on companies’ personnel. Nonetheless, several hacking incidents, involving major companies and public/financial institutions, were actually attempted by the cooperative firms or the outsourced manpower undertaking maintenance work. Specifically, institutions that operate industrial control systems (ICSs) associated with critical national infrastructures, such as traffic or energy, have contracted several cooperative firms. Nonetheless, ICT's importance is gradually increasing, due to outsourcing, and is the most vulnerable factor in security. This paper proposes a virtualized security management scheme for the resident cooperative firms in the industrial control infrastructure. Since such companies often cannot afford adequate investment in security, the scheme is to let an ICS company provide the virtualized system. One of its merits is the convenience of controlling a VDI server at the center. The cooperative firms were classified, based on their respective security levels, and statistics were collected throughout a four-year period for the results. This paper analyzes the policies and virtualization systems that have been applied to the security of the partner companies, which engaged in ICS security. A suitable model for ICS security was then proposed by analyzing their effects on the system efficiencies, based on the comparisons of the security inspection results obtained before and after virtualization. The proposed system is expected to contribute to industrial safety.

항공보안검색 종사자의 직무몰입과 직무만족이 서비스제공에 미치는 영향

항공보안검색 종사자의 직무몰입과 직무만족이 서비스제공에 미치는 영향

An Airport Diversion Security Inspection Model Based on Epidemic Prevention and Control in the Period of COVID-19

During the prevention and control of covid-19 coronavirus, airports are under the dual pressure of the difficulty of epidemic prevention and the low efficiency of security inspection. This paper constructs an airport epidemic prevention and control triage security inspection model, which arranges security checkpoints according to flight schedule. It finds that gender variant queuing can improve the efficiency of security check and reduce the probability of infection, but it can also cause the area of infection to multiply; Reducing the error rate and quality factor of X-ray detector can promote the passing efficiency of security inspection, but the former is more effective; The better the isolation ability of protective equipment such as masks to viruses, the more abundant the means for security inspection departments to improve the efficiency of security inspection.

Generative adversarial networks and faster-region convolutional neural networks based object detection in X-ray baggage security imagery

X-ray images have now been widely used in public transportation security. However, the ever-increasing number of dangerous object types, along with the complexity of the baggage's contents, makes it unsuitable for clearly displaying various baggages and hazards on X-ray images obtained directly from the inspection system. This article aims to improve the detection of dangerous objects by proposing a data augmentation method for enriching the X-ray prohibited item images using a Generative Adversarial Networks(GANs) based approach. Using the improved GANs model, a new X-ray images were generated with better quality and diversity, and the performance of the proposed method was evaluated using FID(Fréchet Inception Distance) score and Faster R-CNN (Region-based Convolutional Neural Network). Experimental results show that the new augmented X-ray security inspection image dataset can improve the detector performance. If other representative training datasets are utilized, we believe that our methodology could aid in the detection of other kinds of threat objects.

Metal Halide Scintillators with Fast and Self‐Absorption‐Free Defect‐Bound Excitonic Radioluminescence for Dynamic X‐Ray Imaging

AbstractScintillators for radiation detection are of great significance in medical imaging, security, and nondestructive inspection. The current challenge for scintillators is to simultaneously achieve high scintillation light yield, fast radioluminescence, simple film fabrication, large X‐ray attenuation efficiency as well as stable and nontoxic compositions; no previous scintillators fulfill all the above requirements. Here, metal halide Rb2AgBr3, possessing defect‐bound excitonic radioluminescence, is shown as efficient and fast scintillators. This nontoxic and stable scintillator emits from excitons bound to neutral bromine vacancies, enjoying an efficient and spin‐allowed fast emission with minimized self‐absorption. Rb2AgBr3 thus has a high light yield (25 600 photons MeV−1), fast scintillation decay time (5.31 ns), and a record value of light yield versus decay time (4821 photons MeV−1 ns−1). The close‐space sublimation method is developed for fast and scalable fabrication of oriented Rb2AgBr3 films. The scintillator film is further integrated with commercial flat‐panel imagers, and the spatial resolution reaches 10.2 line pairs per millimeter at the modulation transfer function of 0.2, doubling the resolution of conventional CsI:Tl flat‐panel detectors. The dynamic X‐ray imaging and its use to real‐time monitoring of bone movement without ghosting effect is also demonstrated.

A Study on Activation Characteristics Generated by 9 MeV Electron Linear Accelerator for Container Security Inspection

A Study on Activation Characteristics Generated by 9 MeV Electron Linear Accelerator for Container Security Inspection

Dangerous goods identification algorithm based on Generative Adversarial Networks

With the continuous progress of deep learning, the application has been extended to the identification of dangerous goods in the security inspection system. The quality of the identification algorithm directly determines the quality of the security inspection system. In this paper, a recognition algorithm based on Generative Adversarial Networks is proposed, which can continuously train the generation model and the discrimination model, and collect the image data samples that are blocked or too small, and then generate images with high similarity, so as to achieve the purpose of detecting and tracking the hidden or small dangerous goods. The experimental results show that the algorithm can effectively detect the dangerous goods and greatly improve the tracking effect.

Characterization of In-House Fabricated Four-Channel Array Si PIN Photodetectors for Radiation-based Image Systems

Radiation-based imaging systems comprise multiple radiation sensors that are assembled with coupled Si PIN (positive — intrinsic — negative) photodetectors and scintillators. This paper describes the fabrication and characterization of a four-channel array Si PIN photodetector for security inspection systems. The Si PIN photodetector was fabricated using conventional (CMOS) processes at the Radiation Equipment Fab. The junction depth, passivation, and anti-reflection layer of the photodetector were controlled to maximize the light detection efficiency and the signal-to-noise ratio. The spectral responsivity obtained was 0.28 A/W for the cadmium tungstate (CWO) emission at a wavelength of 475 nm. Finally, a line pattern image was acquired using the fabricated Si PIN sensor and a self-developed readout and data acquisition system. The significance of this study is it confirms the feasibility of using the developed array-type Si PIN photodetectors in radiation-based imaging systems.