In recent years several papers reported an enhanced dielectric anisotropy when ferroelectric particles were suspended in a liquid crystal. These results seem to be sensitive to the liquid crystal used and the preparation method of the ferroelectric particles. In this paper we compare different preparation methods of suspended barium titanate in two different liquid crystal hosts. As a control experiment we have followed similar preparation steps with non- ferroelectric silica particles. In all cases we found a broadening of the optical Frederiks transition but no change in the dielectric anisotropy. Raman spectroscopy has been used to investigate the loss of tetragonal structure in the barium titanate as a function of milling time and particle size. As reported in the earlier literature barium titanate does not exhibit a well-defined tetragonal crystal structure below a certain particle size and loses its ferroelectric features. This provides a simple rationalisation for the absence of any dielectric enhancement.

关键词：日Frederiks过渡；钛酸钡；液晶主机

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Pedemis (PortablE Decoupled Electromagnetic Induction Sensor) is a time-domain handheld electromagnetic induction (EMI) instrument with the intended purpose of improving the detection and classification of UneXploded Ordnance (UXO). Pedemis sports nine coplanar transmitters (the Tx assembly) and nine triaxial receivers held in a fixed geometry with respect to each other (the Rx assembly) but with that Rx assembly physically decoupled from the Tx assembly allowing flexible data acquisition modes and deployment options. The data acquisition (DAQ) electronics consists of the National Instruments (NI) cRIO platform which is much lighter and more energy efficient that prior DAQ platforms. Pedemis has successfully acquired initial data, and inversion of the data acquired during these initial tests has yielded satisfactory polarizabilities of a spherical target. In addition, precise positioning of the Rx assembly has been achieved via position inversion algorithms based solely on the data acquired from the receivers during the on-time of the primary field. Pedemis has been designed to be a flexible yet user friendly EMI instrument that can survey, detect and classify targets in a one pass solution. In this paper, the Pedemis instrument is introduced along with its operation protocols, initial data results, and current status.

关键词：传感器；电磁感应；军械定位器；算法；背景噪声；数据采集；歧视；手持便携设备；；位置（位置）；灵敏度；时间域；未爆炸的弹药；多目标；pedemis（便携式解耦电磁

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ACC is a driver assistance system that is incorporated into a vehicle to help the driver maintain constant speed and keep safe distance from other vehicles. ACC automatically manages vehicle speed if there is any obstruction in front of the car and warns the driver in an emergency. The purpose of installing an ACC system is to enhance safety and efficiency. It is designed to help prevent accidents caused by driver error such as poor reaction time and drowsiness. This system is highly efficient in warning a driver whenever required and in providing improved comfort during long drives.

关键词：ACC；保持；驾驶辅助系统；速度；安全距离

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Flight systems operating new performance and stability limits require continuous, robust autonomy through real-time performance-based measurements.

关键词：传感器；飞机系统；操作性能

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This paper explores a class of multiple-model-based fault detection and identification (FDI) methods for bias-type faults in actuators and sensors. These methods employ banks of Kalman-Bucy filters to detect the faults, determine the fault pattern, and estimate the fault values, wherein each Kalman-Bucy filter is tuned to a different failure pattern. Necessary and sufficient conditions are presented for identifiability of actuator faults, sensor faults, and simultaneous actuator and sensor faults. It is shown that FDI of simultaneous actuator and sensor faults is not possible using these methods when all sensors have biases.

关键词：传感器；故障检测

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Aerospace applications require a range of sensing technologies. There is a range of sensor and sensor system technologies being developed using microfabrication and micromachining technology to form smart sensor systems and intelligent microsystems. Drive system intelligence to the local (sensor) level -- distributed smart sensor systems. Sensor and sensor system development examples: (1) Thin-film physical sensors (2) High temperature electronics and wireless (3) lick and stick; technology. NASA GRC is a world leader in aerospace sensor technology with a broad range of development and application experience. Core microsystems technology applicable to a range of application environments.

关键词：传感器；测量仪器；微电子学；气体检测器；薄膜；微加工；烟雾检测器

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Man-portable (MP) and Hand-held (HH) adjuncts of the NRL TEMTADS 5 5 array were constructed and the UXO classification performance of each characterized. Both systems are based on the transient electromagnetic induction (TEM) sensor technology that was developed for the NRL TEMTADS 5 5 array. Both systems are designed to be deployable in increasingly inaccessible areas where vehicle-towed sensor arrays cannot be used. Demonstration results for the MP system indicated that the performance of the system was not comparable to that of the full TEMTADS 5 5 array. A modified version of the EMI sensors in the MP system was designed and built, replacing the single, vertical- axes receiver loops of the original coils with three-axis receiver cubes. The HH sensor was designed for use in extremely limiting terrain and for integration with unique positioning technologies. The demonstration results for the HH sensor indicated that the performance of the system was comparable to that of the full TEMTADS 5 5 array.

关键词：传感器，探测器；未爆炸的弹药；电磁感应

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"2013年度中国通信学会科学技术奖励工作会议"于4月24日在北京召开。中国通信学会副理事长兼秘书长、科技奖励工作办公室主任张新生在会议上做了工作报告,对新一届学会领导班子在科技奖励工作方面的思路、规划和部署进行了阐述。工业和信息化部电信研究院于生多副院长、工业和信息化部科技司韩俊

关键词：中国通信学会;奖励工作;工业和信息化部;科学技术奖励;学会副理事长;武汉邮科院;国家科技奖励;烽火网络;工作报告;张新;

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有限元流体热分析软件(CFD)常被用于对LED灯具散热进行建模仿真,与散热相关的参数分析、计算与设置等问题是影响仿真精度的关键因素。综合研究了边界条件设置、热阻计算、热量载荷分析和散热器等仿真建模的关键问题,并与实验室温度测量相结合来验证仿真方法的准确性。结果表明,该方法对室内照明LED灯具能进行较为准确的散热分析,仿真温度误差在4℃左右,仿真结果对LED灯具开发设计具有重要参考价值。

关键词：LED;;散热仿真;;边界条件;;热阻;;辐射系数

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为实现信息网络设备检修工作从"被动抢修"转变为"主动预防",湖北省电力公司借鉴电网一次设备预防性试验、检修工作经验,编制了信息网络设备预防性检测规范,积极开展信息网络设备预防性检测工作,共计提前发现并处理各类信息网络设备缺陷1 753项,确保了信息网络系统安全稳定运行。实践证明,在信息网络设备运维中开展预防性检测工作,不仅可行,而且成效显著。

关键词：信息网络;;设备;;预防性;;检测;;规范;;检修

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