The Miniaturization of the AFIT Random Noise Radar

Advances in technology and signal processing techniques have opened the door to using an UWB random noise waveform for radar imaging. This unique, low probability of intercept waveform has piqued the interest of the U.S. DoD as well as law enforcement and intelligence agencies alike. While AFIT\u27s noise radar has made significant progress, the current architecture needs to be redesigned to meet the space constraints and power limitations of an aerial platform. This research effort is AFIT\u27s first attempt at RNR miniaturization and centers on two primary objectives: 1) identifying a signal processor that is compact, energy efficient, and capable of performing the demanding signal processing routines and 2) developing a high-speed correlation algorithm that is suited for the target hardware. A correlation routine was chosen as the design goal because of its importance to the noise radar\u27s ability to estimate the presence of a return signal. Furthermore, it is a computationally intensive process that was used to determine the feasibility of the processing component. To determine the performance of the proposed algorithm, results from simulation and experiments involving representative hardware were compared to the current system. Post-implementation reports of the FPGA-based correlator indicated zero timing failures, less than a Watt of power consumption, and a 44% utilization of the Virtex-5\u27s logic resources

State of the art survey of technologies applicable to NASA's aeronautics, avionics and controls program

The state of the art survey (SOAS) covers six technology areas including flightpath management, aircraft control system, crew station technology, interface & integration technology, military technology, and fundamental technology. The SOAS included contributions from over 70 individuals in industry, government, and the universities

초고성능 콘크리트의 다기능 복합 응용을 위한 탄소나노튜브의 적용 및 영향 분석

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 건축학과, 2020. 8. 홍성걸.This study aimed to develop multi-functional ultra-high performance concrete (UHPC) with excellent mechanical strength, electromagnetic interference (EMI) shielding effectiveness (SE), and damage sensing capabilities for applying structural health monitoring (SHM), in on-site production. Carbon nanotubes (CNTs), selected as a key material to achieve the purpose of this study, were mixed with UHPC and investigated with regard to dispersion methods, mechanical properties, EMI SE, damage sensing, electrical curing (EC) and structural modifications with respect to CNT incorporation. Ozone treatment was applied to CNTs as a dispersion method and its impact on dispersion of CNTs and hydration reaction of UHPC were investigated. The results reveals that oxygenic and carboxylic groups, formulated by ozone treatment, functionalized the surface of the CNTs and enveloped the cementitious grains, which increasing the degree of dispersion of CNTs and interfacial interaction between CNTs and UHPC particles. Ozone treatment provided multiple nucleation sites and double steric repulsion, accelerating hydration at early ages and improving compressive strength at later ages. Thus, the proposed ozone treatment can be an effective way to disperse CNTs in UHPC. Dispersed CNT suspensions were fabricated using sonication and subsequent shear mixing with superplasticizer, a proposed method for dispersing high content of CNTs in UHPC. Then, the CNT suspensions were incorporated into UHPC to form UHPC/CNT composites and their mechanical properties were investigated with respect to the CNT content. The proposed dispersion method effectively dispersed CNTs within both an aqueous solution and UHPC composite up to the critical incorporation concentration (CIC). In addition, it was found that CNT content below the CIC improve the mechanical properties of UHPC through pore filling, bridging, and calcium-silicate-hydrates (C-S-H) stiffening, whereas CNT content above CIC weakens the properties due to agglomeration of CNTs, suppression of hydration, and increase in air-voids. A dispersed CNTs remarkably improved the electrical conductivity and resulting SE of UHPC up to the percolation threshold. Two testing methods for EMI SE (ASTM D4935-18 and IEEE-STD-299) verified the result and suggested that ASTM D4935-18 can only be used to evaluate a rough trend of SE, and IEEE-STD-299 using the samples with sufficient incident area size at least 1200 × 1200 mm2 should be considered to accurately evaluate the EMI SE at actual structure level. In addition, a practical model to effectively estimate the SE of UHPC was proposed based on statistical analysis of the experimental results. The addition of CNTs significantly decreased electrical resistivity of the UHPC, enabling EC at low voltages in the range of 19–23 V; improved mechanical properties via bridging, pore filling, and C-S-H stiffening effects; and influenced the deflection hardening behavior under flexural stress. Furthermore, the UHPC/CNT under compressive or flexural stress exhibited significant crack sensing capabilities due to the obtained low resistivity. A dramatic fractional change in resistivity (FCR) value of the UHPC/CNT composites can represent the failure under compression or first cracking under flexure. Therefore, it was verified that the UHPC/CNT can extend the applications of UHPC especially for on-site casting and structural crack sensors for UHPCbased structures. Finally, the dispersed CNTs slightly interfered the hydration of the UHPC, but they significantly modified the structure of C-(A)-S-H to be denser, stiffer, and more complex than that of UHPC without CNTs which have been evidenced by observed partial cross-linking in the C-(A)-S-H, reduced d-spacing and the higher fractal dimensions of solid system. Such behaviors were much more significant when EC was applied because the electrical field formed by EC activated ionic polarization and accelerated the chemical reaction among ions in the UHPC matrix, which led to a higher degree of hydration. In conclusion, incorporating appropriate amount of CNTs into UHPC using the proposed dispersion methods can overcome the limitation of UHPC and produce multi-functional UHPC with EMI SE and crack sensing capabilities on-site using EC.이 논문은 뛰어난 기계적 특성 (Mechanical porperties)을 보유했을 뿐만 아니라 전자파 간섭 (Electromagnetic interference, EMI)에 대한 차폐 효과 (Shielding effectiveness, SE), 구조 헬스 모니터링 (Structural health monitoring, SHM) 적용을 위한 균열 자기 감지 (Crack self-sensing) 등 다양한 기능 발휘로 복합 응용이 가능한 초고성능 콘크리트 (Ultra-high performance concrete, UHPC)를 개발하고 현장 시공이 가능토록 하는 것을 목적으로 하였다. 이 연구의 목적을 달성하기 위해 탄소나노튜브 (Carbon Nanotubes, CNTs)를 핵심 재료로 선정하여 UHPC에 혼입하고 분산 방법 (dispersion methods), 기계적 특성, 전자파 차폐, 균열 자기 감지, 전기 경화 (Electrical curing, EC), 그리고 미세구조 변형 (Microstructural modifications) 관점에서 논의 하였다. CNT를 UHPC에 효과적으로 분산시키기 위한 방법 중 하나로 오존 처리 (Ozone treatment)를 적용하고 이에 따른 UHPC의 수화 반응 (Hydration reaction)을 조사하였다. 오존 처리는 산소 및 카르복실기 (Oxygenic and Carboxylic chemical group)를 CNT 표면과 UHPC 입자 주위에 형성하여 효과적으로 CNT를 분산시키고 UHPC의 계면활성작용 (Interfacial interaction)을 개선하였다. 오존 처리는 UHPC 수화 반응에 큰 영향을 미치지는 않았지만 CNT의 효과적인 분산을 통해 다중 핵 형성 반응을 (Multiple nucleation)을 촉진하여 UHPC의 초기 수화 반응을 가속화 할 뿐만 아니라 필러 효과 (Filler effect)로 인해 더욱 더 향상된 압축 강도를 발현하는데 기여하였다. 대용량의 CNT를 UHPC에 균일하게 분산시키기 위하여 초음파 처리 (Sonication) 및 초고성능 감수제 (Super plasticizer)를 활용한 전단 혼합 (Shear mixing) 방법을 제안하였다. 그리고 제안된 분산 방법을 통해 제조된 CNT 분산액을 UHPC와 혼합하고 CNT 혼입 중량에 따른 기계적 특성을 조사하였다. 제안된 분산 방법은 혼입 임계점 (Critical incorporation concentration, CIC) 미만에서 CNT를 효과적으로 분산시킬 수 있었으며 공극 충전 (Pore filling), 가교 효과 (Bridging effect), C-S-H (Calcium-silicatehydrates) 치밀화 (Densification) 등을 통해 압축강도 (Compressive strength) 및 탄성계수 (Elastic modulus)를 향상시켰다. 하지만, 혼입 임계점 이상의 CNT가 혼입된 경우에는 분산된 CNT가 일부 응집 되어 (Agglomeration) UHPC의 수화반응을 방해하고 공극 또는 균열로 작용하여 기계적 특성을 약화시켰다. 분산된 CNT는 침투 임계점 (Percolation threshold) 범위 내에서 UHPC의 전기전도도 (Electrical conductivity) 및 전자파 차폐 효과를 극대화 시켰다. 전자파 차폐 효과를 측정하는 두 가지 표준 시험 (ASTM D4935-18, IEEE-STD-299)을 적용한 결과 ASTM D4935-18은 재료 수준에서 차폐 효과의 대략적인 추세를 평가하는데 사용될 수 있으나 실제 구조 수준에서 정확하게 차폐 효과를 측정하기 위해서는 최소 1200 × 1200 mm2 이상의 충분한 입사면적 (Incident area)을 가지는 실험체로 IEEE-STD-299에 의거 실험해야 함이 입증되었다. UHPC내에 균일하게 분산된 CNT는 UHPC의 전기저항률을 현저히 낮추어 약 19–23 V 범위의 저전압 하에서도 증기 양생과 동등 이상의 효과를 발현하는 전기 경화를 가능하게 하였으며 그 결과 압축강도, 탄성계수, 휨 변형 경화 (Deflection hardening) 등의 기계적 특성이 눈에 띄게 향상되었다. 또한, UHPC/CNT 복합재료는 낮은 전기저항률로 인해 압축 및 휨 응력 하에서 탁월한 균열 자기 감지 능력을 발현하여 구조체의 균열 및 안정성 여부를 판단할 수 근거를 제시하였다. 미세구조 분석 결과, CNT는 UHPC의 중장기 수화 반응을 다소 억제하였지만 C-(A)-S-H의 중간층 (Interlayer) 간격을 줄이고 일부를 연결함으로써 UHPC의 미세구조를 더욱 치밀하게 하고 강성을 강화할 뿐만 아니라 복잡하게 하였다. 이러한 현상은 전기 경화를 적용했을 때 더욱 심화되었는데 이는 전기 경화에 의해 UHPC 매트릭스 내에 형성된 전기장으로 인해 이온 분극 및 화학반응이 가속화되어 수화도가 향상되었기 때문이다. 결론적으로 이 연구에서 제안한 분산 방법을 적용하여 목적에 맞게 적절한 양의 CNT를 UHPC에 혼입하면 UHPC의 한계점을 극복하고 뛰어난 기계적 특성을 발현하는 가운데 전기 경화를 통해 현장 타설이 가능하며 전자파 차폐, 균열 자기 감지 등 다기능 복합 응용이 가능한 UHPC 개발이 가능하다.Chapter 1. Introduction 1 1.1 Background 1 1.1.1 The latest issues in concrete technology 1 1.1.2 Ultra High-Performance Concrete (UHPC) 2 1.1.3 Carbon Nanotubes (CNTs) 4 1.1.4 Compatibility between UHPC and CNTs 6 1.2 Objectives and structure of thesis 9 Chapter 2. Preliminary Study 11 2.1 Literature review 11 2.1.1 Methods to disperse CNTs 11 2.1.2 Cementitious materials incorporated with CNTs for applying EMI shielding 13 2.1.3 Cementitious materials embedded with CNTs for applying SHM techniques 16 2.1.4 Electrical curing (EC) of cementitious materials 18 2.2 Materials used in this study 19 2.3 Basics of microstructural analysis used in this study 21 2.3.1 X-ray diffraction (XRD) 21 2.3.2 Thermogravimetric (TG) analysis 23 2.3.3 Solid-state 29Si nuclear magnetic resonance (NMR) 24 2.3.4 Isothermal calorimetry 25 2.3.5 Mercury intrusion porosimetry (MIP) 27 2.3.6 Small angle X-ray scattering (SAXS) 29 Chapter 3. Ozone Treatment for the Dispersion of CNTs and Hydration Acceleration of UHPC 32 3.1 Introduction 33 3.2 Experimental Details 33 3.2.1 Properties of CNTs 33 3.2.2 Mixture proportions and sample preparation 35 3.2.3 Test methods 38 3.3 Results and Discussion 41 3.3.1 Effect of ozone treatment on dispersion of CNTs 41 3.3.2 Effect of ozone treatment on hydration of UHPC composite 52 3.4 Conclusions 62 Chapter 4. Effect of CNTs on Mechanical Properties of UHPC 64 4.1 Introduction 65 4.2 Experimental Details 65 4.2.1 Properties of CNTs 65 4.2.2 Mixture proportions and sample preparation 65 4.2.3 Test methods 69 4.3 Results and Discussion 70 4.3.1 Degree of dispersion of CNTs 70 4.3.2 Effect of CNTs on Mechanical properties of UHPC 76 4.4 Conclusions 80 Chapter 5. Role of CNTs in the Electromagnetic Shielding Effectiveness of UHPC 83 5.1 Introduction 84 5.2 Experimental Details 84 5.2.1 Mixture proportions and sample preparation 84 5.2.2 Test methods 87 5.3 Results and Discussion 93 5.3.1 Electrical resistivity and conductivity 93 5.3.2 Basics of EMC theory 96 5.3.3 EMI SE results based on two different SE testing method 102 5.3.4 Effects of incident area size on EMI SE 105 5.3.5 Modelling to practically estimate SE of UHPC 115 5.4 Conclusions 126 Chapter 6. Electrically Cured UHPC with CNTs for Field Casting and Crack Self-sensing 128 6.1 Introduction 129 6.2 Experimental Details 129 6.2.1 Properties of CNTs 129 6.2.2 Mixture proportions and sample preparation 132 6.2.3 Test methods 134 6.3 Results and Discussion 137 6.3.1 Flowability 137 6.3.2 Change in temperature and electrical resistivity during curing 137 6.3.3 Morphology of the CNTs in the UHPC 145 6.3.4 Poromechanical properties 147 6.3.5 Compressive strength, elastic modulus, and FCR 149 6.3.6 Flexural strength and FCR 156 6.4 Conclusions 161 Chapter 7. Micro- and Meso-Structural Changes of UHPC by CNTs 164 7.1 Introduction 165 7.2 Experimental Details 165 7.2.1 Mixture proportions and sample preparation 165 7.2.2 Test methods 166 7.3 Results 167 7.3.1 X-ray diffraction 167 7.3.2 Thermogravimetric anlaysis 170 7.3.3 29Si NMR spectroscopy 172 7.3.4 Small angle X-ray scattering 179 7.4 Discussion 190 7.5 Conclusions 193 Chapter 8. Conclusions 195 Reference 201 Appendix 218 초 록 224Docto

Electronic warfare self-protection of battlefield helicopters : a holistic view

The dissertation seeks to increase understanding of electronic warfare (EW) self-protection (EWSP) of battlefield helicopters by taking a holistic (systems) view on EWSP. It also evaluates the methodologies used in the research and their suitability as descriptive tools in communication between various EWSP stakeholders. The interpretation of the term "holistic view" is a central theme to the dissertation. The research methodology is bottom-up – which is necessary since no previous work exists that could guide the study – and progresses from analysis to synthesis. Initially several methods are evaluated for presenting findings on EWSP, including high-level system simulation such as Forrester system dynamics (FSD). The analysis is conducted by a comprehensive literature review on EW and other areas that are believed to be of importance to the holistic view. Combat scenarios, intelligence, EW support, validation, training, and delays have major influence on the effectiveness of the EWSP suite; while the initial procurement decision on the EWSP suite sets limits to what can be achieved later. The need for a vast support structure for EWSP means that countries with limited intelligence and other resources become dependent on allies for support; that is, the question of EWSP effectiveness becomes political. The synthesis shows that a holistic view on EWSP of battlefield helicopters cannot be bounded in the temporal or hierarchical (organizational) senses. FSD is found to be helpful as a quality assurance tool, but refinements are needed if FSD is to be useful as a general discussion tool. The area of survivability is found to be the best match for the holistic view – for an EWSP suprasystem. A global survivability paradigm is defined as the ultimate holistic view on EWSP. It is suggested that future research should be top-down and aiming at promoting the global survivability paradigm. The survivability paradigm would give EWSP a natural framework in which its merits can be assessed objectively.reviewe

DRONE DELIVERY OF CBNRECy – DEW WEAPONS Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD)

Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD) is our sixth textbook in a series covering the world of UASs and UUVs. Our textbook takes on a whole new purview for UAS / CUAS/ UUV (drones) – how they can be used to deploy Weapons of Mass Destruction and Deception against CBRNE and civilian targets of opportunity. We are concerned with the future use of these inexpensive devices and their availability to maleficent actors. Our work suggests that UASs in air and underwater UUVs will be the future of military and civilian terrorist operations. UAS / UUVs can deliver a huge punch for a low investment and minimize human casualties.https://newprairiepress.org/ebooks/1046/thumbnail.jp

Advanced RFI detection, RFI excision, and spectrum sensing : algorithms and performance analyses

Because of intentional and unintentional man-made interference, radio frequency interference (RFI) is causing performance loss in various radio frequency operating systems such as microwave radiometry, radio astronomy, satellite communications, ultra-wideband communications, radar, and cognitive radio. To overcome the impact of RFI, a robust RFI detection coupled with an efficient RFI excision are, thus, needed. Amongst their limitations, the existing techniques tend to be computationally complex and render inefficient RFI excision. On the other hand, the state-of-the-art on cognitive radio (CR) encompasses numerous spectrum sensing techniques. However, most of the existing techniques either rely on the availability of the channel state information (CSI) or the primary signal characteristics. 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