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控制导线传感器测量
After the recent success in jamming wireless improvised explosive devices (IEDs), the threat nowadays has shifted towards the use of buried command wires. A capability to immediately detect the presence of a command wire would be of great value to the troops on the ground. The major challenge of a command wire sensor is to detect the wire in clutter and achieve a high probability of detection without large number of false alarms. The objective of this thesis is to investigate the wire scattering behavior and clutter characteristics through measurements performed in the NPS anechoic chamber. The research has successfully resolved the various multipath components within the anechoic chamber. The transmit-receive coupling between the antennas was reduced through the appropriate use of absorbers. Various wire scattering and clutter characteristics were established through the measurement results. In addition, the measurement results have also demonstrated close-in clutter rejection by utilizing time gating. Recommendations for future work were proposed to gather more data to support the ongoing NPS research on the Command Wire Sensor design.
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先进传感器技术对于国防部土壤蒸气入侵问题的应用
This study demonstrated the use of a unique prototype gas chromatograph with sensor array detection, the analytical components of which are microfabricated from Si (micro-GC), for analysis of indoor air concentrations of trichloroethylene (TCE) at low- and sub ppb levels, related to vapor intrusion (VI) applications. The objectives of this study were to demonstrate the performance of the prototype micro-GC in two operating modes: portable mode for forensic and spatial monitoring; and fixed location mode for longer term temporal monitoring (exposure estimation). Results from the micro GC and from TO -15 reference samples were compared. Above the mitigation action level (MAL; 2.3 ppb), the micro-GC accurately determined TCE under complex field matrix conditions. Below the MAL, TCE micro GC determinations were positively biased due to unresolved interferences. This study stands as the first of its kind, where micro-GC instrumentation was shown capable of sustained, reliable, automated measurements of a trace-level component (TCE) in a complex VOC mixture in real-world environments.
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用于海上封锁操作和地区安全的专用传感器网络
Robust communications are key to the success of naval operations such as area surveillance, control, and interdiction. Communications and sensor networks allow the flow of data and critical information that are necessary for conducting such operations from both tactical and strategic perspectives. In naval operations, platforms are hardly stationary, as the networking infrastructure operates from a variety of platforms in motion on the sea, above the sea, and from space. Sensor networks consist of nodes made up of small sensors that are able to monitor, process, and analyze phenomena over geographical regions of varying size and for significant periods. Some categories of these small sensors are able to collect and transmit sensor data about physical values (e.g., temperature, humidity, and sea state), or dynamic attributes of objects, such as speed, direction, and the existence of dangerous substances (e.g., radioactive materials and explosives). The objective of this thesis is to examine how unstructured sensor networks, known as ad-hoc sensor networks, can effectively support maritime interdiction operations and regional security by providing reliable communications and flow of information.
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微流矢量传感器在水下使用的可行性研究
This thesis investigates the feasibility of adapting the Microflown PU match vector sensor for underwater use. After testing the proper functioning of the sensor, the best materials for the capsule are determined based on acoustic properties. The capsule is designed and built by NPS staff. To predict the sensitivity of the encapsulated sensor, the characteristic equations are modified to reflect the new medium. In order to be able to predict the sensitivity of the encapsulated sensor, the performance ratio is determined between the sensitivity in air and the filling fluid of choice. Temperature dependency is introduced in the relevant parameters to be able to model the sensitivity at various operating temperatures. The measured sensitivity from the calibration report is then used to predict its performance in castor oil. The theoretical sensitivity model is verified by experimental data gathered from calibration studies at NUWC. The verified model is then used to analyze the consequences of changing critical operating parameters like the distance between the filaments and the operating temperature. Based on these calculations, recommendations are made for a better performing prototype. Eventually a new design is proposed that increases sensitivity significantly and is better adapted to operate in the filling fluid.
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传感器数据完整性和感知故障的缓解
This report describes basic research to analyze and investigate methods for automatic detection and mitigation of sensor and perception data. Specifically, the PI will investigate (1) Metrics for sensor performance in context using multi-modal redundancy and information theoretic approaches; (2) Detection, localization and mitigation of faults and failures using hierarchical causal reasoning for diagnosis; (3) Develop methods for using low- level (e.g., sensor data fusion filter) versus high-level (autonomous inference) processes for automated selection of data to use for perception.
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CMOS图像传感器的设计
Image sensors have become significant due to the high demand from different applications. Charge-Coupled Device (CCD) and Complementary Metal-Oxide Semiconductor (CMOS) image sensors are two different technologies used for capturing images digitally. Both types of imagers are fabricated in silicon and convert light into electronic signals for processing. Section 3.1 of this chapter discusses briefly the CCDs and CMOS image sensors. Section 3.2 gives an overview of the photodetection in silicon. The different types of photodiodes used to sense the light intensity are discussed. Section 3.3 discusses the basic types of pixels commonly used in CMOS image sensors. The advantages and disadvantages of each type are elaborated. Section 3.4 discusses the performance parameters of the CMOS image sensors and section 3.5 presents the peripheral circuits used in conventional CMOS image sensors. Section 3.6 describes the design of a 128×128 pixel CMOS image sensor chip with in-pixel analog memory and a 1-bit dynamic memory in a standard 0.18μm 1-poly-3-metal CMOS CIS (CMOS Image Sensor) process. The characterization and measurement results of the image sensor are also presented in section 3.7.
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无线传感器网络中能源意识和效率:从物理设备到通信链接
Wireless sensor networks (WSNs) represent a new domain of distributed computing that has attracted great research interest over the last years. A WSN is composed of a large number of tiny battery-operated devices equipped with one or more sensing units, processor, memory, and wireless radio. The main goal of WSNs is to collect data about physical phenomena and deliver them to user applications through one or more exit points called sink nodes. Sink nodes are powerful devices, often a personal computer, that are in charge of gathering all the sensor-collected data, further processing them, and making them available to external networks such as the Internet.
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基于GPS定位性能和传感器协助需求的单一频率和载波相位的分析
The work described in this report outlines the design and testing of a low-cost, single frequency, carrier phase positioning system. Furthermore, aiding sensor accuracy requirements are analyzed to improve the robustness of the carrier phase system after emerging from signal outages. The applications of interest are ones with safety-of-life implications such as driver assist systems for enhancing lane keeping performance in narrow lanes or during inclement weather when lane markings are obscured. In these applications, frequent GPS outages due to obstructions from buildings and highway overpasses often require solving for the integer ambiguities. The single frequency GPS receiver used for this work was the Hemisphere Crescent. Processing carrier phase data from this receiver was only intermittently successful. Even for data sets collected under ideal static and open-sky conditions, the integer ambiguity estimation process was often unsuccessful. Much effort was made to identify the source of the problem, but no conclusive reason was identified. Despite this setback, sensor accuracy requirements were studied analytically. and it was determined that aiding sensors capable of providing baseline vector position estimates with a standard deviation of less than 0:8 m have potential to improve the integer ambiguity resolution time. This requirement, especially for signal outages lasting longer than several seconds, limits the candidate aiding sensors to higher-cost systems. Therefore low-cost, carrier phase based driver assist systems, using currently available receivers and sensors, continues to be a challenging problem. However, this may be overcome in the next decade as the second and third GPS civilian signal, L2C and L5, become fully avialable by 2019.
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通过集成一个手持EMI传感器的惯性测量单元来提高辨识性能
We compared classification capabilities for handheld electromagnetic sensors that were deployed using either a grid-based template for spatial registration or an IMU-based positioning system. Demonstration data were collected at the Aberdeen Proving Ground using both systems. The two data sets were analyzed separately and submitted to the Institute for Defense Analyses for grading. The IMU-based positioning system involved in this demonstration is known as the Small Area Inertial Navigation and Tracking (SAINT) system. It was developed by ENSCO as part of an earlier ESTCP project and enhanced and integrated with the EM61HH sensor in support of this effort. The SAINT system consists of a Honeywell HG1900 IMU and a LEICA DMC. The Honeywell HG1900 IMU consists of orthogonally aligned MEMS accelerometers and gyroscopes that record 3-axis acceleration and rotation rates, respectively enclosed in an 8-cubic inch container. The LEICA DMC is employed to aid the IMU and constrain heading drift. The digital magnetic compass measures the strength and direction of a magnetic field and can be used to determine magnetic north in an environment free of additional magnetic fields. SAINT records all IMU and digital magnetic compass data onto an internal compact flash card.
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对于高灵敏度的具有电子声音的MEMS定向传感器的集成
The miniaturization of a sound detection system is of great interest to applications such as sniper location. Current systems in use are larger and do not provide for the unencumbered movement of the warfighter. Inspiration for a smaller MEMS based sensor is therefore taken from the aural system of the fly Ormia ochracea. The focus of this thesis is the design of an integrated and miniaturized device utilizing commercial-off-the-shelf readout electronics with the biologically inspired sensor. An analysis of previously used techniques is presented along with a novel fullyintegrated miniaturized design. Specific investigations include integration with external readout electronics, a hybrid discrete component design, and the fully-integrated single package design. Results include successful operation at all levels of integration and a more thorough analysis of the performance of the fully-integrated design.