EOS MLS cloud ice measurements and cloudy-sky radiative transfer model

A cloud ice retrieval technique is described here using measurements at frequencies near 118, 190, 240, and 640 GHz and 2.5 THz from the Earth Observing System Microwave Limb Sounder on the NASA Aura satellite. Measurement principles, methods for cloud detection, and radiative transfer models for retrieving cloud properties are discussed. The 240-GHz data from high-tangent heights are used to retrieve ice water content at pressures <215 hPa, and the 118-, 190-, 240-, and 640-GHz radiances from low-tangent heights are used to retrieve ice water paths with different penetration depths. Some early Microwave Limb Sounder (MLS) results are highlighted, and the observed cloud signatures are consistent with the expectation from model simulations, in general. The simultaneous measurements from MLS 240 and 640 GHz radiometers contain useful information on particle sizes. There are significant cloud-induced radiances at 2.5 THz, despite strong attenuation from the atmosphere. Cloud-scattering signatures are polarized at 122 GHz, but the polarization differences are typically less than 10% of the total cloud-induced radiance.     

High-speed optical transmission systems using advanced monolithicIC technologies

The authors discuss the design and performance of monolithic ICs for multigigabit lightwave transmission systems including direct detection and coherent detection. The required function and performance of a lightwave transmitter and receiver are discussed. The fabricated ICs and their application to the transmission system are shown in a direct system. Microwave monolithic ICs for lightwave heterodyne detection and an interconnection technique are introduced. Future trends of ICs are discussed     

核壳型磁性颗粒微波磁导率模拟与实验研究

采用有效媒质理论模拟和实验验证的方法,研究了核壳型磁性颗粒的微波磁导率。结果表明:核壳结构有利于提高微波下颗粒的复磁导率,2GHz时,其实部比氧化后的颗粒提高6%~12%,虚部提高15%~30%。片状椭球形核壳结构优于球形核壳结构,2GHz时,20nm壳层厚的片状颗粒的复磁导率为4.85–1.71i,而同壳层厚的球状颗粒为4.55–1.31i。在核壳结构的颗粒中,壳层厚度薄有利于改善磁导率。     

Differentiation between melt and freeze stages of the melt cycle using SSM/I channel ratios

Microwave remote sensing detection of snow melt and ablation generally focuses on the detection of liquid moisture in the snow-pack. For ablation estimation, it is important to determine if wet snow is in the process of melting or freezing. The different stages of the melt cycle are observed in the diurnal variation of T/sub b/ measurements from the Special Sensor Microwave Imager (SSM/I) over Greenland. SSM/I channel ratios exhibit patterns indicating that they are sensitive to melt and freeze stages of the daily melt cycle. The horizontal to vertical polarization ratio is sensitive to surface wetness associated with melting. The 19-37-GHz frequency ratio is sensitive to a frozen surface layer over wet snow which is associated with the freeze stage of the melt cycle. These observations are supported by conceptual models presented here and in in situ measurements from other investigators.     

Tissue sensing adaptive radar for breast cancer detection: study of immersion liquids

Microwave breast cancer detection is based on the differences in electrical properties of malignant tumours and normal fatty tissues. Radar-based approaches involve interpreting information in ultra-wideband reflections from the breast. A key issue in the design of radar-based tumour detection systems is selection of a substance to couple the breast and antenna. Several liquids are compared and the benefits of selecting an oil-based immersion liquid are shown     

基于被动毫米波的运动目标探测技术

针对被动毫米波技术对高速运动目标探测能力不足的问题,采用 基于单片微波集成电路(Monolithic Microwave Integrated Circuit, MMIC)的直接检波式 毫米波辐射计构建了一种被动毫米波探测系统,并通过试验获得了不同条 件下对高速运动目标的实测数据。在对测试信号的特征进行分析的基础上,指出 第一脉冲的峰值和两个峰值脉冲的间距能够反映目标运动特性的有效特征,并提出了 一种用于计算目标运动速度的方法。结果表明,该方法具有一定的精度,可在被动毫米 波系统中用于确定运动目标的参数。     

基于被动干涉微波亮温图像的海面目标探测算法研究

为利用被动干涉微波技术作为我国天基预警体系的重要补充以实现对海面目标的有效探测，该文提出一种基于被动干涉微波图像的海面目标探测算法。首先，建立了海面背景和海面目标的被动干涉微波图像数学模型；其次，详细地介绍了海面目标的探测算法，并仿真验证了算法的可行性；最后，开展了机载实验。理论分析和实验验证均表明:该探测算法是可行性的，能有效地探测到海面目标，且具有较好的探测性能；海面航行的金属目标在被动干涉微波图像中呈现“一高一低”的特征，可利用该特征提高海面目标探测概率。该探测算法可为天基被动干涉微波技术探测海面目标提供参考。     

Millimeter Waveband Dielectric Properties of Nanocomposite Materials Based on Opal Matrices with Particles of Spinels

The dielectric properties of 3D nanocomposites based on opal matrices containing the particles of compounds with spinel structure have been studied. Microwave measurements have been carried out in the frequency range from 26 to 38 GHz. The frequency dependences of transmission and reflection coefficients are obtained. The values of the real and imaginary parts of complex dielectric permittivity have been retrieved. The X-ray phase analysis of the nanocomposites is performed and their structures are studied.     

Performance Analysis of Temperature and Strain Simultaneous Measurement System Based on Heterodyne Detection of Brillouin Scattering

Microwave heterodyne detection can be used to measure the temperature and strain distribution along a fiber with high accuracy in a Brillouin optical time domain reflectometry （BOTDR） system. This method involves simultaneous measurement of Brillouin scattering and Rayleigh scattering in fiber, and scanning of Brillouin spectrum to obtain the desired information. This paper presents a simultaneous measurement system of temperature and strain based on microwave detection and analyzed the system performances such as measurement accuracy, dynamic range, and spatial resolution theoretically. The analysis shows that the system can achieve a temperature resolution of 1°C and a strain resolution of 100 μs.     

Multimodal Damage Detection in Self‐Sensing Fiber Reinforced Composites

Internal delamination damage is detected in fiber reinforced polymer composite materials containing active functionality. Damage‐triggered magnetization of the delaminated zone is accomplished using a vascular system to deliver fluids that precipitate magnetic particles upon mixing. Multiple modes of detection are used to sense the presence of this magnetic material. Visual detection is accomplished by the high contrast between damaged and undamaged areas provided by the biomimetic “bruise” formed by the magnetic particles. Magnetic scanning is also used to detect the particles, even if obscured by paint or by opaque reinforcement, such as carbon fiber. Additionally, thermal detection is accomplished by inductively heating the magnetic particles and sensing the temperature differential with an infrared camera. The effectiveness of each detection mode is discussed and compared to industry standard C‐scan to assess accuracy. Using the damage area measured with C‐scan as the benchmark, visual detection measures the damage area with 76% accuracy, and magnetic detection measures the damage area with 91% accuracy. Thermal detection accuracy is time‐dependent as expected. All detection modes consistently detect the presence of damage. The multifunctionality of this material can tailor damage detection techniques for the application and provide a parallel system to augment and potentially enhance self‐healing.     

Tissue sensing adaptive radar for breast cancer detection - experimental investigation of simple tumor models

Microwave breast cancer detection is based on differences in electrical properties between healthy and malignant tissues. Tissue sensing adaptive radar (TSAR) has been proposed as a method of microwave breast imaging for early tumor detection. TSAR senses all tissues in the volume of interest and adapts accordingly. Simulation results have shown the feasibility of this system for detecting tumors of 4 mm in diameter. In this paper, the second-generation experimental system for TSAR is presented. Materials with electrical properties similar to those in the breast are used for the breast model. A resistively loaded Wu-King monopole antenna is fabricated, and reflections from the breast model over the frequency range of 1-10 GHz are recorded. The reflected signals are processed with the TSAR algorithm, which includes improved skin subtraction and TSAR focusing algorithms. Various tumor models are examined; specifically, a 1-cm tumor is detected with a signal-to-clutter ratio of 10.41 dB. Tumor detection with the experimental system is evaluated and compared to simulation results.     

基于目标函数的微波超视距雷达天线高度优化方法

利用海上蒸发波导可以使舰载微波超视距雷达实现远距离低空目标探测,然而大气波导内的超折射和多径传播效应会产生不利于目标检测的雷达盲区。该文提出一种基于目标函数的微波超视距雷达天线高度优化方法,针对形成蒸发波导的海-气界面稳定层结、中性层结和不稳定层结3种情况,利用电波传播数值算法和雷达评估模型仿真分析了蒸发波导内特定区域不同目标函数时的雷达目标检测性能,给出了雷达天线高度优化结果。该文方法可以为微波超视距雷达系统设计、探测性能分析和大气环境自适应技术提供参考。     

Localized Collection of Airborne Analytes: A Transport Driven Approach to Improve the Response Time of Existing Gas Sensor Designs

The detection of single binding has been a recent trend in sensor research introducing various sensor designs where the active sensing elements are nanoscopic in size. Currently, transport and collection of airborne analytes for gas sensors is either diffusion based or non‐localized and it becomes increasingly unlikely for analytes to interact with sensing structures where the active area is shrunk, trading an increased sensitivity with a slow response time. This report introduces a corona discharge based analyte charging method and an electrodynamic nanolens based analyte concentration concept to effectively transport airborne analytes to sensing points to improve the response time of existing gas sensor designs. Localized collection of analytes over a wide range, including microscopic particles, nanoparticles, and small molecules, is demonstrated. In all cases, the collection rate is several orders of magnitudes higher than in the case where the collection is driven by diffusion. The collection scheme is integrated on an existing SERS (surface‐enhanced Raman spectroscopy) based sensor. In terms of response time, the process is able to detect analytes at 9 ppm (parts per million) within 1 s. As a comparison, 1 h is required to reach the same signal level when diffusion‐only‐transport is used.     

微波技术在大脑深层信息探测的应用研究进展

微波技术对大脑信息进行探测正处于发展时期,目前正逐渐走向成熟,现已用于实体的检测与操作中。通过联合超声波、核磁等方法,完善了微波信息探测体系,增强了微波信息探测的效率。本文基于对大脑深层信息探测的3种微波技术以及现有微波探测技术中存在的问题进行总结,并对微波技术未来在大脑信息探测上的应用进行展望。通过对3种不同微波探测应用的分析,发现微波技术对大脑的探测具有巨大的潜力。这些应用可以有效地为脑部组织或人体其他组织的病态检查提供解决方案。同时,通过与人工智能结合,微波技术还可用于脑部的远程监测或身体的其他部位的远程监测中。     

A, Model for Tracheobronchial Clearance of Inhaled Particles in Man and a Comparison with Data

We report the development of a mathematical model for the mucociliary clearance of inhaled particles in the normal human lung. The model assumes Weibel's symmetric dichotomously branching system of airways in the lung. The model is formulated by assuming that the particles residing on the surface of the mucus blanket behave as a fluid and that their concentration is governed by the continuity equation. The concentration of particles in each airway generation of the lung is found to depend on the initial deposition pattern and the transport rate of mucus in each airway generation. The distribution of particles is determined by a model calculation which takes into account inertial impaction, gravitational sedimentation, and Brownian diffusion as the principal mechanisms of particle deposition. The mucus transport rates are found by first assuming that the mucus blanket which lines the airways is uniformly thick throughout the entire lung and that there is no net absorption or secretion of mucus in a given airway generation. The only mucociliary transport rate which has been well measured experimentally is in the trachea. We adjust the trachael transport rate in the model until a good agreement between predicted and observed clearance of 7.9?aerodynamic diameter particles from the lung is obtained. The tracheal transport rate necessary to achieve a good fit is 5.5 mm/min which agrees with measured values. With an established trachael transport rate we are then able to calculate transport rates in distal airways.     

OAM mechanisms in MPLS layer 2 transport networks

This article describes OAM in MPLS layer 2 transport networks. MPLS networks used to transport layer 2 traffic are referred to as MPLS layer 2 transport networks. They may be used to connect legacy layer 2 networks and/or provide layer 2 service to a user over a MPLS network. As legacy layer 2 networks migrate to use MPLS for transport, the role of MPLS OAM mechanisms is becoming increasingly important. This is because the converged network must offer the same OAM functionality as existing layer 2 networks. This article emphasizes the importance of end-to-end OAM, while emulating existing layer 2 services using MPLS transport. End-to-end fault detection is described in the context of various layer 2 over MPLS transport network models. The article focuses on state-of-the-art MPLS label switched path and pseudo wire OAM mechanisms being developed by the IETF. This includes fault detection and isolation mechanisms such as LSP-Ping, bidirectional forwarding detection, and virtual circuit connectivity verification. The applicability of each of these mechanisms is given. In some cases it may be possible to carry layer 2 OAM cells end-to-end, while in other cases this may not be possible. The relationship between segment-based OAM mechanisms and end-to-end OAM is described for each of these cases.     

Microfluidic Synthesis of Liquid Crystalline Elastomer Particle Transport Systems which Can Be Remote‐Controlled Magnetically

Here, the microfluidic synthesis of liquid crystalline elastomer (LCE) particles, which can be remote‐controlled magnetically and used as transport systems, is presented for the first time. Ferri‐magnetic, rod‐shaped Fe₃O₄ nanoparticles are functionalized with poly(methyl methacrylate) to make them compatible with organic LCE precursor compounds. Their influence on the LCE precursor alignment is studied and thermoresponsive as well as photoresponsive LCE microparticles containing 0–6 wt% Fe₃O₄ are synthesized with a microfluidic device. Thermal and photochemical actuations of these particles are investigated. Their magnetic addressability is studied with a recently developed magnetic setup, by which the particles can be guided on liquid surfaces in the centimeter range–but with a precision in the submillimeter range. This allows the performance of reversible light‐ or heat‐controlled actuations at desired positions. The potential of synthesized LCE particles as transport systems is demonstrated by the transport of plastic, textiles or copper, which can be pushed just due to magnetic forces or transported in general by taking advantage of the phase dependent “stickiness” of LCEs. These studies open doors to novel applications of LCEs as microrobots using magnetism as a control.     

A generalized Einstein relation for semiconductors

The Einstein relation relates the diffusion coefficient to the mobility and is frequently used in semiconductor device analysis and design. A flux equation governing the behavior of mobile particles in semiconductor material is derived from the Boltzmann transport equation. The particles are assumed to obey quantum statistics. The flux equation provides the formal means for defining the transport parameters D and μ.A generalized Einstein relation valid for any particle density under equilibrium as well as non-equilibrium conditions is derived. The relation is given in terms of Fermi integrals and a scattering parameter. Once the scattering parameter is specified, the Einstein relation can be easily evaluated. The asymptotic limit for degenerate material is also given.     

Technology Summaries for Microwave Theory and Techniques--1983

This paper consists of compendia of advances for the calendar year 1983 in four selected technical areas of interest to the microwave community. These four areas are Hybrid MIC's, Microwave and Millimeter-Wave Solid-State Devices, Microwave Field Theory, and Microwave Systems.     

Radar Absorbing Structures Using Frequency Selective Surfaces: Trends and Perspectives

Journal of Electronic Materials - Microwave radar absorbers are widely used in the strategic sector and wireless communication systems to reduce the radar cross-section of a target and...