Sensor Scheduling for Target Tracking in Networks of Active Sensors

Wireless sensor network (WSN) of active sensors suffers from serious inter-sensor interference (ISI) and imposes new design and implementation challenges. In this paper, based on the ultrasonic sensor network, two time-division based distributed sensor scheduling schemes are proposed to deal with ISI by scheduling sensors periodically and adaptively respectively. Extended Kalman filter (EKF) is used as the tracking algorithm in distributed manner. Simulation results show that the adaptive sensor scheduling scheme can achieve superior tracking accuracy with faster tracking convergence speed.

Disbond detection with piezoelectric wafer active sensors in RC structures strengthened with FRP composite overlays

The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.

Total ionizing dose effects in pinned photodiode complementary metal-oxide-semiconductor transistor active pixel sensor

A pinned photodiode complementary metal–oxide–semiconductor transistor（CMOS） active pixel sensor is exposed to ^60Co to evaluate the performance for space applications. The sample is irradiated with a dose rate of 50 rad（SiO2）/s and a total dose of 100 krad（SiO2）, and the photodiode is kept unbiased. The degradation of dark current, full well capacity,and quantum efficiency induced by the total ionizing dose damage effect are investigated. It is found that the dark current increases mainly from the shallow trench isolation（STI） surrounding the pinned photodiode. Further results suggests that the decreasing of full well capacity due to the increase in the density, is induced by the total ionizing dose（TID） effect, of the trap interface, which also leads to the degradation of quantum efficiency at shorter wavelengths.

Analysis of proton and γ-ray radiation effects on CMOS active pixel sensors

Radiation effects on complementary metal-oxide-semiconductor（CMOS） active pixel sensors（APS） induced by proton and γ-ray are presented. The samples are manufactured with the standards of 0.35 μm CMOS technology. Two samples have been irradiated un-biased by 23 MeV protons with fluences of 1.43 × 10^11 protons/cm^2 and 2.14 × 10^11 protons/cm-2,respectively, while another sample has been exposed un-biased to 65 krad（Si） ^60Co γ-ray. The influences of radiation on the dark current, fixed-pattern noise under illumination, quantum efficiency, and conversion gain of the samples are investigated. The dark current, which increases drastically, is obtained by the theory based on thermal generation and the trap induced upon the irradiation. Both γ-ray and proton irradiation increase the non-uniformity of the signal, but the nonuniformity induced by protons is even worse. The degradation mechanisms of CMOS APS image sensors are analyzed,especially for the interaction induced by proton displacement damage and total ion dose（TID） damage.

Piezoelectric Actuator/Sensor Wave Propagation Based Nondestructive Active Monitoring Method of Concrete Structures

In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.

MOS-based model of four-transistor CMOS image sensor pixels for photoelectric simulation

By using the MOS-based model established in this paper, the physical process of photoelectron generation, transfer,and storage in the four-transistor active pixel sensor(4 T-APS) pixels can be simulated in SPICE environment. The variable capacitance characteristics of double junctions in pinned photodiodes(PPDs) and the threshold voltage difference formed by channel nonuniform doping in transfer gates(TGs) are considered with this model. The charge transfer process of photogenerated electrons from PPDs to the floating diffusion(FD) is analyzed, and the function of nonuniform doping of TGs in suppressing charge injection back to PPDs is represented with the model. The optical and electrical characteristics of all devices in the pixel are effectively combined with the model. Moreover, the charge transfer efficiency and the voltage variation in PPD can be described with the model. Compared with the hybrid simulation in TCAD and the Verilog-A simulation in SPICE, this model has higher simulation efficiency and accuracy, respectively. The effectiveness of the MOS-based model is experimentally verified in a 3 μm test pixel designed in 0.11 μm CIS process.

Crack monitoring using multiple smart materials;fiber-optic sensors&piezo sensors

This article focuses on health monitoring of structures using multiple smart materials.In this research,two fiber-optic sensors,namely fiber Bragg grating(FBG)and fiber-optic polarimetric sensor(FOPS),are investigated for damage detection in the beam specimen.FBG is used for local strain measurement while FOPS is used for global strain measurement.Both FBG and FOPS show significant changes in the strain due to damages in the specimen.Also,at the center of the specimen,piezoelectric wafer active sensor(PWAS)is attached.The electromechanical admittance(EMA)signature of the specimen beam is recorded by PWAS.The changes in the amplitudes of the peaks obtained at various frequencies in this EMA signature are analyzed,and it is shown that the peak amplitudes respond differently to damages and to change in loading.Thus,multiple smart materials(FBG,FOPS,and PWAS)are used to get improved information on the health of the beam.

A cancer cell turn-on protein-CuSMn nanoparticle as the sensor of breast cancer cell and CH_3O-PEG-phosphatide

Cancer activated protein-inorganic nanoparticles can be cancer targeting turn-on imaging and therapy agents. Although various techniques were successfully employed for development of hybrid proteininorganic nanoparticles, cancer cell activated protein-inorganic nanoparticles have been challengeable.Herein, a cancer cell responsive nanoparticle（PDAMn-CuS@BSA-FA, NPs） was constructed and characterized. It is found that the quenching interaction of dyes（PDA） and central metal in NPs can be adjusted by CH_3O-PEG-phosphatide or the cancer cells, hence, NPs showed turn-on fluorescence emission with the titration of CH_3O-PEG-phosphatide. In particular, breast cancer cells lysis can switch on the green emission greatly, while normal cells show less effect. Breast cancer cells turn-on fluorescence imaging and mitochondria targeting imaging demonstrate that the NPs can sense breast cancer cells and enter mitochondria. Therefore, NPs can be both breast cancer targeting nanosensor.

Highly sensitive hybrid nanofiber-based room-temperature CO sensors： Experiments and density functional theory simulations

Chemical sensors （CSs） are an emerging area in nanoscience research, which focuses on the highly sensitive detection of toxic and hazardous gases and disease- related volatile organics. While the field has advanced rapidly in recent years, it lacks the theoretical support required for the rational design of innovative materials with tunable measurement responses. Herein, we present a one-dimensional （1D） hybrid nanofiber decorated with ultrafine NiO nanoparticles （NiO NPs） as an efficient active component for CSs. Highly dispersed （110）-facet NiO NPs with a high percentage of Ni2~ active sites with unsaturated coordination were confined in a TiO2 nanofiber （TiO2 NF） matrix that is favorable for surface catalytic reactions. The CSs constructed using the 1D heterostructure NiO/TiO2 nanofibers （NiOdrio2 HNFs） exhibited a highly selective response to trace CO gas molecules （1 ppm） with high sensitivity （AR/Ro = 1.02）, ultrafast response/ recovery time （T 〈 20 s）, and remarkable reproducibility at room tem- perature. The density functional theory （DFT） simulations and experimental results confirmed that the selective response could be attributed to the high molecular adsorption energy of the NiO nanoparticles with （110） facets and abundant interfaces, which act synergistically to promote CO adsorption and facilitate charge transfer.

Application of dynamic sensor activation on operating automated headlights

The controller in an automated vehicle relies on sensors to collect the information needed for handling traffic situations,and reducing the frequency of using sensors could prolong theirlifespans.We present in this paper the application of dynamic sensor activation algorithms in discrete event systems to activate/deactivate sensors for colecting information when it is only necessary to automatically operate headlights based on trafic rules.The framework developed in this paper forms a basis for automatically activating/deactivating sensors for other components in an automated vehicle in the future.

Brightness Independent 4-Star Matching Algorithm for Lost-in-Space 3-Axis Attitude Acquisition

A star identification algorithm was developed for a charge-coupled device （CCD） or complementary metal-oxide-semiconductor （CMOS） autonomous star tracker to acquire 3-axis attitude information for a lost-in-space spacecraft. The algorithm took advantage of an efficient on-board database and an original “4- star matching” pattern recognition strategy to achieve fast and reliable star identification. The on-board database was composed of a brightness independent guide star catalog （mission catalog） and a K-vector star pair catalog. The star pattern recognition method involved direct location of star pair candidates and a sim- ple array matching procedure. Tests of the algorithm with a CMOS active pixel sensor （APS） star tracker result in a 99.9% success rate for star identification for lost-in-space 3-axis attitude acquisition when the angular measurement accuracy of the star tracker is at least 0.01°. The brightness independent algorithm requires relatively higher measurement accuracy of the star apparent positions that can be easily achieved by CCD or CMOS sensors along with subpixel centroiding techniques.