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The metal-dielectric-metal multilayer structure sensor with a transparent top layer and an opaque bottom layer is proposed, which can provide a perfect narrow-band absorption resonance and is suitable for sensing refractive index change of the liquid to be measured in dielectric layer. The Fabry-Perot resonance analytical model that can accurately reproduce response spectrum and theoretically analyze the mechanism of the dielectric layer thickness to tune resonance wavelength and linewidth of response spectrum is constructed. Theoretical analysis shows that the resonance wavelength is directly proportional to the thickness of dielectric layer, and the full width at half maximum is inversely proportional to the thickness of dielectric layer. The analytical expressions for its resonance wavelength, quality factor, full width at half maximum and sensitivity are also given. When used for the refractive index sensing, the quality factor and figure of merit of the proposed multilayer structure based on the 8th order Fabry-Perot resonance are 2162.8 and 1648.1 RIU–1, respectively. However, due to the influence of the minimum resolution of the spectrometer, the conventional method of measuring resonance wavelength shift to achieve refractive index sensing has a high measurement limit. For the sensing of weaker refractive index perturbation, with the help of superposition of exceptional point degenerate state and tuning mechanism of Fabry-Perot resonance, in this paper proposed is a method of tunably sensing the liquid refractive index by measuring the increase of reflection coefficient or splitting of eigenvalue at a specific wavelength. Here, we take for example the metal-dielectric-metal multilayer structure sensor based on the 8th order Fabry-Perot resonance. According to the calculation results of Fabry-Perot model, when the change in refractive index of liquid to be measured is 10–4 RIU, the increase of forward reflection coefficient and the splitting of two eigenvalues of the scattering matrix are 0.319 and 1.1279, respectively.

The air-bridge interconnection is an extremely effective structure for improving the device performance in MMICs, but its application is limited by the complexity in fabrication and high temperature process required for baking photoresist. In this paper, we present a low temperature $( process for the fabrication of air-bridge in microwave devices. By choosing two types of suitable photoresists and optimizing the hard baking time of the sacrificial photoresist, we obtain high structural strength arched structure air-bridges with the entire process carried out at low temperature and complexity reduced. We have successfully fabricated four-finger HEMT devices.

Minimizing the impact of radiation-induced degradation in optoelectronic devices based dilute nitride is crucial in applications. The effects of 1MeV electron irradiation (1×1014 e/cm2 ~ 1×1016 e/cm2 range) on undoped GaInNAs/GaAs single quantum well (QW) structure has been studied by low temperature photoluminescence (PL). PL spectra of GaInNAs/GaAs QW are measured before and after electron irradiation. The results show a slight enhancement of the PL intensity in relatively low electron fluence, and then subsequent deterioration of PL with increase of cumulative electron fluence. The enhancement in PL intensity at low electron doses are explained by recombination-enhanced defect reaction model and the degradation at high electron doses are explained by irradiation induced defects in lattice.

Diabetic cystopathy is a common complication of voiding disorders in diabetes mellitus. Neuropathy and bladder remodeling underlie the lack of efficacy of pharmacological and surgical treatments. Previous studies have shown that decreased levels of nerve growth factor (NGF) are closely associated with disease progression. Besides, application of human umbilical cord mesenchymal stem cells (hUC-MSCs) is also considered a promising therapeutic strategy for treatment of diabetic neuropathy. In our study, we determine the therapeutic efficacy and mechanisms of hUC-MSCs which transfected with NGF geen in ameliorating diabetic cystopathy for the first time. We transducted hUC-MSCs with NGF-expressing lentivirus so that the hUC-MSCs can express NGF efficiently, then the NGF-expressing hUC-MSCs were intrathecally administrated in L6-S1 spinal cord of diabetic rats 3 days after induced by streptozotocin. Nine weeks later, the level of neurotrophins and voiding function of bladder were detected. Results show that improvements in voiding function were related to the neurotrophins and cytokines released by the intrathecally transplanted hUC-MSCs. In addition, the hUC-MSCs also differentiated into neurons and astrocytes within the spinal cord in rats. These two mechanisms play a combined role in neural regeneration and the amelioration of the symptoms of diabetic cystopathy.

Scramjet is crucial to develop hypersonic technology. The hypersonic vehicles with scramjet as power de- vice are of much significance for national defense security and space transportation. In this paper, the requirements for thermal protection materials of scramjet were analyzed and current status of the application of C/SiC composites in scramjet was reviewed. At last, the development proposals and key problems needed to be solved for C/SiC compos

A novel statistical method based on particle filtering is presented for multiple vehicle acoustic signals separation problem in wireless sensor network. The particle filtering method is able to deal with non-Gaussian and nonlinear models and non-stationary sources. Using some instantaneously mixed observations of several real-world vehicle acoustic signals, the proposed statistical method is compared with a conventional non-stationary Blind Source Separation algorithm and attractive simulation results are achieved. Moreover, considering the natural convenience to transmit particles between sensor nodes, the algorithm based on particle filtering is believed to have potential to enable the task of multiple vehicles recognition collaboratively performed by sensor nodes in distributed wireless sensor network.

There is continued and growing interest in using low voltage power networks to realize "the last mile". It is necessary and important for any communication system to study the noise characteristics of the communication channel. This paper presents noise measurements on three typical low voltage networks in the frequency range of (500 k/spl sim/10 M) Hz. The noise measurements include: power-line background noise, appliance noise and noise sampled over a 24-hour period The conclusion that has been reached is that the noise level in the (500 k/spl sim/10 M) Hz is much lower than that in the (10 k-450 k) Hz ranges. Finally the paper gives a rough estimate of the channel capacity.

We present a theoretical modeling method to predict the ring tool influence function (TIF) based on the computer-controlled active lap process. The gap on the lap-grinding layer is considered, and its influence on the ring TIF is analyzed too. The relationship between the shape of the ring TIF and the lap-workpiece rotation speed ratio is discussed in this paper. The recipe for calculating dwell time for axisymmetric fabrication is discussed. The grinding process of a 1.8 m primary mirror is improved based on these results. The grinding process is accomplished after 30 circles of grinding, and the surface shape error is from PV 82 μm RMS 16.4 μm reduced to PV 13.5 μm RMS 2.5 μm.

A low power broad band CMOS LNA for software-defined radio (SDR) applications is presented. The LNA is based on the common source cascade amplifier with active feedback. To realize a high gain bandwidth, the inductor shunt peaking technology was used. In order to acquire a good S11 performance over a high frequency band range, a parallel RC network feedback was used too. By using the forward body bias technology, the cascade LNA can operate under 1V supply voltage to reduce the power consumption. The LNA was fabricated using a 90nm RF CMOS technology. The measurement results show that the LNA achieves a bandwidth of 8.4 GHz from 0.1–8.5GHz with a 16.3 dB voltage gain, noise figures from 2.7 dB to 3.9 dB across the whole band, and an input third-order intermodulation product (IIP3) of −4 dBm, the power consumption is about 10 mW without the buffer under the 1V supply voltage.

To prolong the life of the whole network, this paper has proposed an energy balanced and anti-interference routing algorithm for wireless sensor networks based on power control. This routing algorithm will select the path with nodes which can provide relatively a higher stability, more energy and their location are closer to sink node so that the energy of each node can be balanced and network delay can be reduced with parallel transmission. Experimental data have shown that the algorithm called EBAR proposed in this paper can provide the whole network a relatively more balanced energy consumption, a less transmission delay and a lower rate of packet loss than AODV algorithm and NAVC-AODV algorithm.

This paper considers the problem of classifying simultaneous multiple ground vehicles using their acoustic signatures recorded by unattended passive acoustic sensor array. The proposed approach relies on the blind source separation (BSS) algorithm based on time-frequency signal representations. Instead of estimating mixing parameters as the original algorithm do, we get the missing feature mask from the BSS step. Then an acoustic signature recognizer based on the missing feature theory recognizes each acoustic source. Recognition results are presented for several simultaneous vehicle acoustic signals. Compared with familiar ways, using both the missing feature theory and BSS algorithm results in high performance improvement

Wireless location methods in sensor network have received significant attention in recent years. In this paper, we present a data fusion architecture and explore a Fuzzy Optimization data fusion (FODF). Simulation results show that the overall accuracy of location estimation in wireless location systems can be significantly improved when the fuzzy optimization data fusion methods are used.

In this paper, a novel recognition system based on rough neural network is presented for the application of vehicle classification in wireless sensor network. The proposed system is evaluated using real-world signal datasets as well as two conventional methods. Compared with them, approach based on rough neural network achieves high performance improvement. Furthermore, the purposed system is extended for multi-channel sensor data fusion directly. Since the experiment results are attractive, algorithm based on rough neural network is believed to have potential for applications of recognition and data fusion in wireless sensor networks.

The refractive index sensing properties of a period array of subwavelength metallic slits in water environment are investigated. The transmission spectra of the slit array are calculated with a rigorous fully-vectorial method. A simple semi-analytical Fabry-Perot model that can accurately reproduce the rigorous fully-vectorial data is built up. We find that the transmission peak becomes sharpest as it is exactly located at the Rayleigh anomaly position, which is explained based on the resonance condition derived from the model. The method to design the slit array to achieve this sharpest transmission peak is presented. The full width at half-maximum (δλ) of the designed transmission peak can be as low as 0.01 nm, which corresponds to a refractive-index measurement uncertainty (δns) of 2× 10-6 RIU. The influences of array period, slit width and incident angle on the designed sensitivity, δλ, δns and peak transmittance of the sensor are systematically provided.

The mathematical model of the vibration-based piezoelectric generator with the proof mass supported by a cantilever is established.The formulas of the frequency,the output voltage and the output power are derived.Testing results show that this model is more accurate than Roundy's model.According to such characters as large transient power and small average power of the typical wireless sensor node,the power self-regulation circuit of the piezoelectric multi-shaker micro-generator is proposed.When the electricity in the super capacitor of the main circuit is enough to power the wireless sensor node,the main circuit is opened by the ancillary return circuit and the node starts to measure and transfer the results to the monitoring center.The field test on an engine of a ship shows that the vibration-based piezoelectric generator can be used to power a wireless sensor node.

This paper presents the general solution of noncircular uniform waveguides in an arbitrary coordinate system. It can be expressed as exp{i(+ΔβV)z}E0(x,y),where V is a matrix depending uniquely on the angle θ between polarization principal axis (PPA) and coordinate axis. As a kind of application, we give the method to find , Δβ and V(θ) in the weak-guided fiber, whose distortion is smaller.It is easier to use it for analyzing the effect of birefringence decreasing due to the lognitudinal asymmetry in a fiber, compared with Jones matrix.

Polarization mode dispersion (PMD) is the ultimate limitation to high bit-rate fibre communication system. The stability of PMD is very important to its measurement and compensation. This paper puts forward a method to measure the stability of PMD by measuring the stability of the state of polarization (SOP) and introduces the conception of time evolution vector (TEV) of SOP. We observe the fact that the regularity of the principal state of polarization changing with time is the same as other SOPs', if we neglect the dependence of TEV on wavelength. We also measure the SOP's stability of some fibres with different lengths and obtain results of PMD changing with time.