Science.gov

Sample records for active sensor configuration

  1. 3D active edge silicon sensors with different electrode configurations: Radiation hardness and noise performance

    NASA Astrophysics Data System (ADS)

    Da Viá, C.; Bolle, E.; Einsweiler, K.; Garcia-Sciveres, M.; Hasi, J.; Kenney, C.; Linhart, V.; Parker, Sherwood; Pospisil, S.; Rohne, O.; Slavicek, T.; Watts, S.; Wermes, N.

    2009-06-01

    3D detectors, with electrodes penetrating the entire silicon wafer and active edges, were fabricated at the Stanford Nano Fabrication Facility (SNF), California, USA, with different electrode configurations. After irradiation with neutrons up to a fluence of 8.8×10 15 n eq cm -2, they were characterised using an infrared laser tuned to inject ˜2 minimum ionising particles showing signal efficiencies as high as 66% for the configuration with the shortest (56 μm) inter-electrode spacing. Sensors from the same wafer were also bump-bonded to the ATLAS FE-I3 pixel readout chip and their noise characterised. Most probable signal-to-noise ratios were calculated before and after irradiation to be as good as 38:1 after the highest irradiation level with a substrate thickness of 210 μm. These devices are promising candidates for application at the LHC such as the very forward detectors at ATLAS and CMS, the ATLAS B-Layer replacement and the general pixel upgrade. Moreover, 3D sensors could play a role in applications where high speed, high-resolution detectors are required, such as the vertex locators at the proposed Compact Linear Collider (CLIC) at CERN.

  2. Accuracy-energy configurable sensor processor and IoT device for long-term activity monitoring in rare-event sensing applications.

    PubMed

    Park, Daejin; Cho, Jeonghun

    2014-01-01

    A specially designed sensor processor used as a main processor in IoT (internet-of-thing) device for the rare-event sensing applications is proposed. The IoT device including the proposed sensor processor performs the event-driven sensor data processing based on an accuracy-energy configurable event-quantization in architectural level. The received sensor signal is converted into a sequence of atomic events, which is extracted by the signal-to-atomic-event generator (AEG). Using an event signal processing unit (EPU) as an accelerator, the extracted atomic events are analyzed to build the final event. Instead of the sampled raw data transmission via internet, the proposed method delays the communication with a host system until a semantic pattern of the signal is identified as a final event. The proposed processor is implemented on a single chip, which is tightly coupled in bus connection level with a microcontroller using a 0.18 μm CMOS embedded-flash process. For experimental results, we evaluated the proposed sensor processor by using an IR- (infrared radio-) based signal reflection and sensor signal acquisition system. We successfully demonstrated that the expected power consumption is in the range of 20% to 50% compared to the result of the basement in case of allowing 10% accuracy error. PMID:25580458

  3. Accuracy-Energy Configurable Sensor Processor and IoT Device for Long-Term Activity Monitoring in Rare-Event Sensing Applications

    PubMed Central

    2014-01-01

    A specially designed sensor processor used as a main processor in IoT (internet-of-thing) device for the rare-event sensing applications is proposed. The IoT device including the proposed sensor processor performs the event-driven sensor data processing based on an accuracy-energy configurable event-quantization in architectural level. The received sensor signal is converted into a sequence of atomic events, which is extracted by the signal-to-atomic-event generator (AEG). Using an event signal processing unit (EPU) as an accelerator, the extracted atomic events are analyzed to build the final event. Instead of the sampled raw data transmission via internet, the proposed method delays the communication with a host system until a semantic pattern of the signal is identified as a final event. The proposed processor is implemented on a single chip, which is tightly coupled in bus connection level with a microcontroller using a 0.18 μm CMOS embedded-flash process. For experimental results, we evaluated the proposed sensor processor by using an IR- (infrared radio-) based signal reflection and sensor signal acquisition system. We successfully demonstrated that the expected power consumption is in the range of 20% to 50% compared to the result of the basement in case of allowing 10% accuracy error. PMID:25580458

  4. Methods and Systems for Configuring Sensor Acquisition Based on Pressure Steps

    NASA Technical Reports Server (NTRS)

    DeDonato, Mathew (Inventor)

    2015-01-01

    Technologies are provided for underwater measurements. A system includes an underwater vessels including: a plurality of sensors disposed thereon for measuring underwater properties; and a programmable controller configured to selectively activate the plurality of sensors based at least in part on underwater pressure. A user may program at what pressure ranges certain sensors are activated to measure selected properties, and may also program the ascent/descent rate of the underwater vessel, which is correlated with the underwater pressure.

  5. Effect of Electrode Configuration on Nitric Oxide Gas Sensor Behavior.

    PubMed

    Cui, Ling; Murray, Erica P

    2015-01-01

    The influence of electrode configuration on the impedancemetric response of nitric oxide (NO) gas sensors was investigated for solid electrochemical cells [Au/yttria-stabilized zirconia (YSZ)/Au)]. Fabrication of the sensors was carried out at 1050 °C in order to establish a porous YSZ electrolyte that enabled gas diffusion. Two electrode configurations were studied where Au wire electrodes were either embedded within or wrapped around the YSZ electrolyte. The electrical response of the sensors was collected via impedance spectroscopy under various operating conditions where gas concentrations ranged from 0 to 100 ppm NO and 1%-18% O₂ at temperatures varying from 600 to 700 °C. Gas diffusion appeared to be a rate-limiting mechanism in sensors where the electrode configuration resulted in longer diffusion pathways. The temperature dependence of the NO sensors studied was independent of the electrode configuration. Analysis of the impedance data, along with equivalent circuit modeling indicated the electrode configuration of the sensor effected gas and ionic transport pathways, capacitance behavior, and NO sensitivity. PMID:26404312

  6. Effect of Electrode Configuration on Nitric Oxide Gas Sensor Behavior

    PubMed Central

    Cui, Ling; Murray, Erica P.

    2015-01-01

    The influence of electrode configuration on the impedancemetric response of nitric oxide (NO) gas sensors was investigated for solid electrochemical cells [Au/yttria-stabilized zirconia (YSZ)/Au)]. Fabrication of the sensors was carried out at 1050 °C in order to establish a porous YSZ electrolyte that enabled gas diffusion. Two electrode configurations were studied where Au wire electrodes were either embedded within or wrapped around the YSZ electrolyte. The electrical response of the sensors was collected via impedance spectroscopy under various operating conditions where gas concentrations ranged from 0 to 100 ppm NO and 1%–18% O2 at temperatures varying from 600 to 700 °C. Gas diffusion appeared to be a rate-limiting mechanism in sensors where the electrode configuration resulted in longer diffusion pathways. The temperature dependence of the NO sensors studied was independent of the electrode configuration. Analysis of the impedance data, along with equivalent circuit modeling indicated the electrode configuration of the sensor effected gas and ionic transport pathways, capacitance behavior, and NO sensitivity. PMID:26404312

  7. Methodology on high ratio multiple configuration systems in image sensor

    NASA Astrophysics Data System (ADS)

    Liu, Hua; Ding, Quanxin; Zhou, Liwei

    2014-12-01

    The method of a multiple configuration on high ratio systems in image sensor is an important subject. In such an experimental configuration, for aim to break through to large ratio multiple configuration systems bottlenecks, achieve the field of continuous transformation, effect system close to the theoretical limit and configuration dexterity, such as the purpose, method in the design of the integrated sensor system process, the core technology of such a system are thoroughly analyzed and the factors important to the compromise. Theory is studied based on the theory of Gaussian optical system error distribution and comprehensive balancing algorithm; Global optimization method, developed at a system design thought and the optimization model. Results solved the MTF matching problem, research and evaluations shows that the zoom ratio of more than one hundred results in system MTF and so on as qualitative criterion to achieve requirements.

  8. Evaluation of Sensor Configurations for Robotic Surgical Instruments

    PubMed Central

    Gómez-de-Gabriel, Jesús M.; Harwin, William

    2015-01-01

    Designing surgical instruments for robotic-assisted minimally-invasive surgery (RAMIS) is challenging due to constraints on the number and type of sensors imposed by considerations such as space or the need for sterilization. A new method for evaluating the usability of virtual teleoperated surgical instruments based on virtual sensors is presented. This method uses virtual prototyping of the surgical instrument with a dual physical interaction, which allows testing of different sensor configurations in a real environment. Moreover, the proposed approach has been applied to the evaluation of prototypes of a two-finger grasper for lump detection by remote pinching. In this example, the usability of a set of five different sensor configurations, with a different number of force sensors, is evaluated in terms of quantitative and qualitative measures in clinical experiments with 23 volunteers. As a result, the smallest number of force sensors needed in the surgical instrument that ensures the usability of the device can be determined. The details of the experimental setup are also included. PMID:26516863

  9. Evaluation of Sensor Configurations for Robotic Surgical Instruments.

    PubMed

    Gómez-de-Gabriel, Jesús M; Harwin, William

    2015-01-01

    Designing surgical instruments for robotic-assisted minimally-invasive surgery (RAMIS) is challenging due to constraints on the number and type of sensors imposed by considerations such as space or the need for sterilization. A new method for evaluating the usability of virtual teleoperated surgical instruments based on virtual sensors is presented. This method uses virtual prototyping of the surgical instrument with a dual physical interaction, which allows testing of different sensor configurations in a real environment. Moreover, the proposed approach has been applied to the evaluation of prototypes of a two-finger grasper for lump detection by remote pinching. In this example, the usability of a set of five different sensor configurations, with a different number of force sensors, is evaluated in terms of quantitative and qualitative measures in clinical experiments with 23 volunteers. As a result, the smallest number of force sensors needed in the surgical instrument that ensures the usability of the device can be determined. The details of the experimental setup are also included. PMID:26516863

  10. Crack detection sensor layout and bus configuration analysis

    NASA Astrophysics Data System (ADS)

    Sharp, Nathan; Kuntz, Alan; Brubaker, Cole; Amos, Stephanie; Gao, Wei; Gupta, Gautam; Mohite, Aditya; Farrar, Chuck; Mascareñas, David

    2014-05-01

    In crack detection applications large sensor arrays are needed to be able to detect and locate cracks in structures. Emerging graphene-oxide paper sensing skins are a promising technology that will help enable structural sensing skins, but in order to make use of them we must consider how the sensors will be laid out and wired on the skin. This paper analyzes different sensor shapes and layouts to determine the layout which provides the preferred performance. A ‘snaked hexagon’ layout is proposed as the preferred sensor layout when both crack detection and crack location parameters are considered. In previous work we have developed a crack detection circuit which reduces the number of channels of the system by placing several sensors onto a common bus line. This helps reduce data and power consumption requirements but reduces the robustness of the system by creating the possibility of losing sensing in several sensors in the event that a single wire breaks. In this paper, sensor bus configurations are analyzed to increase the robustness of the bused sensor system. Results show that spacing out sensors in the same bus as much as possible increases the robustness of the system and that at least 3 buses are needed to prevent large segments of a structure from losing sensing in the event of a bus failure. This work is a preliminary effort toward enabling a new class of ‘networked materials’ that will be vitally important for next generation structural applications. ‘Networked materials’ have material properties related to information theoretic concepts. An example material property is ‘bandwidth’ per unit of material that might indicate the amount of information the material can provide about its state-of-health.

  11. A configurable sensor network applied to ambient assisted living.

    PubMed

    Villacorta, Juan J; Jiménez, María I; Del Val, Lara; Izquierdo, Alberto

    2011-01-01

    The rising older people population has increased the interest in ambient assisted living systems. This article presents a system for monitoring the disabled or older persons developed from an existing surveillance system. The modularity and adaptability characteristics of the system allow an easy adaptation for a different purpose. The proposed system uses a network of sensors capable of motion detection that includes fall warning, identification of persons and a configurable control system which allows its use in different scenarios. PMID:22346668

  12. A Configurable Sensor Network Applied to Ambient Assisted Living

    PubMed Central

    Villacorta, Juan J.; Jiménez, María I.; del Val, Lara; Izquierdo, Alberto

    2011-01-01

    The rising older people population has increased the interest in Ambient Assisted Living systems. This article presents a system for monitoring the disabled or older persons developed from an existing surveillance system. The modularity and adaptability characteristics of the system allow an easy adaptation for a different purpose. The proposed system uses a network of sensors capable of motion detection that includes fall warning, identification of persons and a configurable control system which allows its use in different scenarios. PMID:22346668

  13. Application of particle swarm techniques in sensor network configuration

    NASA Astrophysics Data System (ADS)

    Tillett, Jason; Yang, Shanchieh J.; Rao, Raghuveer; Sahin, Ferat

    2005-05-01

    A decentralized version of particle swarm optimization called the distributed particle swarm optimization (DPSO) approach is formulated and applied to the generation of sensor network configurations or topologies so that the deleterious effects of hidden nodes and asymmetric links on the performance of wireless sensor networks are minimized. Three different topology generation schemes, COMPOW, Cone-Based and the DPSO--based schemes are examined using ns-2. Simulations are executed by varying the node density and traffic rates. Results contrasting heterogeneous vs. homogeneous power reveal that an important metric for a sensor network topology may involve consideration of hidden nodes and asymmetric links, and demonstrate the effect of spatial reuse on the potency of topology generators.

  14. Comparison of three different configurations of an optical sensor for tip-clearance measurements in turbines

    NASA Astrophysics Data System (ADS)

    García, Iker; Zubia, Joseba; Berganza, Amaia; Beloki, Josu; Mateo, Javier; Vazquez, Carmen

    2014-05-01

    The influence of the tip clearance on the performance of rotating turbo machinery is well known. The objective of this work was to measure this parameter using a non-contact sensor with a precision of 30 μm in a real turbine. An optical sensor whose main component is a bundle of optical fibers was selected to carry out the measurements. Three different configurations of the sensor have been tested by taking measurements on two distinct turbines. Tip-clearance measurements are achieved with the desired precision, providing the opportunity to develop applications related to structural health monitoring or active clearance-control systems.

  15. Choosing Sensor Configuration for a Flexible Structure Using Full Control Synthesis

    NASA Technical Reports Server (NTRS)

    Lind, Rick; Nalbantoglu, Volkan; Balas, Gary

    1997-01-01

    Optimal locations and types for feedback sensors which meet design constraints and control requirements are difficult to determine. This paper introduces an approach to choosing a sensor configuration based on Full Control synthesis. A globally optimal Full Control compensator is computed for each member of a set of sensor configurations which are feasible for the plant. The sensor configuration associated with the Full Control system achieving the best closed-loop performance is chosen for feedback measurements to an output feedback controller. A flexible structure is used as an example to demonstrate this procedure. Experimental results show sensor configurations chosen to optimize the Full Control performance are effective for output feedback controllers.

  16. Configuring a Context-Aware Middleware for Wireless Sensor Networks

    PubMed Central

    Gámez, Nadia; Cubo, Javier; Fuentes, Lidia; Pimentel, Ernesto

    2012-01-01

    In the Future Internet, applications based on Wireless Sensor Networks will have to support reconfiguration with minimum human intervention, depending on dynamic context changes in their environment. These situations create a need for building these applications as adaptive software and including techniques that allow the context acquisition and decisions about adaptation. However, contexts use to be made up of complex information acquired from heterogeneous devices and user characteristics, making them difficult to manage. So, instead of building context-aware applications from scratch, we propose to use FamiWare, a family of middleware for Ambient Intelligence specifically designed to be aware of contexts in sensor and smartphone devices. It provides both, several monitoring services to acquire contexts from devices and users, and a context-awareness service to analyze and detect context changes. However, the current version of FamiWare does not allow the automatic incorporation related to the management of new contexts into the FamiWare family. To overcome this shortcoming, in this work, we first present how to model the context using a metamodel to define the contexts that must to be taken into account in an instantiation of FamiWare for a certain Ambient Intelligence system. Then, to configure a new context-aware version of FamiWare and to generate code ready-to-install within heterogeneous devices, we define a mapping that automatically transforms metamodel elements defining contexts into elements of the FamiWare family, and we also use the FamiWare configuration process to customize the new context-aware variant. Finally, we evaluate the benefits of our process, and we analyze both that the new version of the middleware works as expected and that it manages the contexts in an efficient way. PMID:23012505

  17. Self-Configuring Indoor Localization Based on Low-Cost Ultrasonic Range Sensors

    PubMed Central

    Basaran, Can; Yoon, Jong-Wan; Son, Sang Hyuk; Park, Taejoon

    2014-01-01

    In smart environments, target tracking is an essential service used by numerous applications from activity recognition to personalized infotaintment. The target tracking relies on sensors with known locations to estimate and keep track of the path taken by the target, and hence, it is crucial to have an accurate map of such sensors. However, the need for manually entering their locations after deployment and expecting them to remain fixed, significantly limits the usability of target tracking. To remedy this drawback, we present a self-configuring and device-free localization protocol based on genetic algorithms that autonomously identifies the geographic topology of a network of ultrasonic range sensors as well as automatically detects any change in the established network structure in less than a minute and generates a new map within seconds. The proposed protocol significantly reduces hardware and deployment costs thanks to the use of low-cost off-the-shelf sensors with no manual configuration. Experiments on two real testbeds of different sizes show that the proposed protocol achieves an error of 7.16∼17.53 cm in topology mapping, while also tracking a mobile target with an average error of 11.71∼18.43 cm and detecting displacements of 1.41∼3.16 m in approximately 30 s. PMID:25310467

  18. A Fault Tolerant System for an Integrated Avionics Sensor Configuration

    NASA Technical Reports Server (NTRS)

    Caglayan, A. K.; Lancraft, R. E.

    1984-01-01

    An aircraft sensor fault tolerant system methodology for the Transport Systems Research Vehicle in a Microwave Landing System (MLS) environment is described. The fault tolerant system provides reliable estimates in the presence of possible failures both in ground-based navigation aids, and in on-board flight control and inertial sensors. Sensor failures are identified by utilizing the analytic relationships between the various sensors arising from the aircraft point mass equations of motion. The estimation and failure detection performance of the software implementation (called FINDS) of the developed system was analyzed on a nonlinear digital simulation of the research aircraft. Simulation results showing the detection performance of FINDS, using a dual redundant sensor compliment, are presented for bias, hardover, null, ramp, increased noise and scale factor failures. In general, the results show that FINDS can distinguish between normal operating sensor errors and failures while providing an excellent detection speed for bias failures in the MLS, indicated airspeed, attitude and radar altimeter sensors.

  19. Technical activities of the configuration aeroelasticity branch

    NASA Technical Reports Server (NTRS)

    Cole, Stanley R. (Editor)

    1991-01-01

    A number of recent technical activities of the Configuration Aeroelasticity Branch of the NASA Langley Research Center are discussed in detail. The information on the research branch is compiled in twelve separate papers. The first of these topics is a summary of the purpose of the branch, including a full description of the branch and its associated projects and program efforts. The next ten papers cover specific projects and are as follows: Experimental transonic flutter characteristics of supersonic cruise configurations; Aeroelastic effects of spoiler surfaces mounted on a low aspect ratio rectangular wing; Planform curvature effects on flutter of 56 degree swept wing determined in Transonic Dynamics Tunnel (TDT); An introduction to rotorcraft testing in TDT; Rotorcraft vibration reduction research at the TDT; A preliminary study to determine the effects of tip geometry on the flutter of aft swept wings; Aeroelastic models program; NACA 0012 pressure model and test plan; Investigation of the use of extension twist coupling in composite rotor blades; and Improved finite element methods for rotorcraft structures. The final paper describes the primary facility operation by the branch, the Langley TDT.

  20. Comparative study of characteristics of polysilicon pressure sensor with different diaphragm sizes and piezoresistor configurations

    NASA Astrophysics Data System (ADS)

    Kumar, S. Santosh; Ojha, Anuj K.; Kumar, Manish; Pant, B. D.

    2016-04-01

    In this work, the fabrication and characterization of eight different polysilicon piezoresistive pressure sensors are reported. The sensors are fabricated simultaneously by putting the different designs on the same mask set and the sensitivity and non-linearity characteristics are plotted. The output responses of the different sensors are reported at three temperatures (-5, 25 and 55 °C). Out of the eight sensors with different diaphragm sizes and piezoresistor configurations, the sensor with diaphragm edge length of 1,280 µm and 2x1 configuration is found to have optimum characteristics, with good non-linearity and acceptable sensitivity. For this sensor, a sensitivity of 3.83-4.26 mV/Bar and non-linearity of <0.38 % are obtained in the pressure range of 0-30 Bar.

  1. Sensor Configuration Selection for Discrete-Event Systems under Unreliable Observations

    SciTech Connect

    Wen-Chiao Lin; Tae-Sic Yoo; Humberto E. Garcia

    2010-08-01

    Algorithms for counting the occurrences of special events in the framework of partially-observed discrete event dynamical systems (DEDS) were developed in previous work. Their performances typically become better as the sensors providing the observations become more costly or increase in number. This paper addresses the problem of finding a sensor configuration that achieves an optimal balance between cost and the performance of the special event counting algorithm, while satisfying given observability requirements and constraints. Since this problem is generally computational hard in the framework considered, a sensor optimization algorithm is developed using two greedy heuristics, one myopic and the other based on projected performances of candidate sensors. The two heuristics are sequentially executed in order to find best sensor configurations. The developed algorithm is then applied to a sensor optimization problem for a multiunit- operation system. Results show that improved sensor configurations can be found that may significantly reduce the sensor configuration cost but still yield acceptable performance for counting the occurrences of special events.

  2. Sensor configuration and test for fault diagnoses of subway braking system based on signed digraph method

    NASA Astrophysics Data System (ADS)

    Zuo, Jianyong; Chen, Zhongkai

    2014-05-01

    Fault diagnosis of various systems on rolling stock has drawn the attention of many researchers. However, obtaining an optimized sensor set of these systems, which is a prerequisite for fault diagnosis, remains a major challenge. Available literature suggests that the configuration of sensors in these systems is presently dependent on the knowledge and engineering experiences of designers, which may lead to insufficient or redundant development of various sensors. In this paper, the optimization of sensor sets is addressed by using the signed digraph (SDG) method. The method is modified for use in braking systems by the introduction of an effect-function method to replace the traditional quantitative methods. Two criteria are adopted to evaluate the capability of the sensor sets, namely, observability and resolution. The sensors configuration method of braking system is proposed. It consists of generating bipartite graphs from SDG models and then solving the set cover problem using a greedy algorithm. To demonstrate the improvement, the sensor configuration of the HP2008 braking system is investigated and fault diagnosis on a test bench is performed. The test results show that SDG algorithm can improve single-fault resolution from 6 faults to 10 faults, and with additional four brake cylinder pressure (BCP) sensors it can cover up to 67 double faults which were not considered by traditional fault diagnosis system. SDG methods are suitable for reducing redundant sensors and that the sensor sets thereby obtained are capable of detecting typical faults, such as the failure of a release valve. This study investigates the formal extension of the SDG method to the sensor configuration of braking system, as well as the adaptation supported by the effect-function method.

  3. Sensor Configuration For A Short To Medium Range Reconnaissance Pod

    NASA Astrophysics Data System (ADS)

    Johansson, Ingvar H.

    1987-02-01

    The GREEN BARON pod is designed and developed specifically for penetrating reconnaissance and for reconnaissance up to medium distance. An Infra Red Line Scanner (IRLS) in combination with a panoramic camera are the main short range sensors, the IRLS as an allweather sensor and the panoramic camera to get horizon to horizon coverage and stereo interpretation. For reconnaissance up to medium distance our choice was a camera with 12 inch focal length. This focal length gives moderate focusing problems when operating over a wide distance range. Influence on performance caused by environment is easier to deal with compared to operating a camera with longer focal length. This paper concentrates on the reasons for choosing a focal length of 12 inch for the pod.

  4. A Novel Optimal Configuration form Redundant MEMS Inertial Sensors Based on the Orthogonal Rotation Method

    PubMed Central

    Cheng, Jianhua; Dong, Jinlu; Landry, Rene Jr.; Chen, Daidai

    2014-01-01

    In order to improve the accuracy and reliability of micro-electro mechanical systems (MEMS) navigation systems, an orthogonal rotation method-based nine-gyro redundant MEMS configuration is presented. By analyzing the accuracy and reliability characteristics of an inertial navigation system (INS), criteria for redundant configuration design are introduced. Then the orthogonal rotation configuration is formed through a two-rotation of a set of orthogonal inertial sensors around a space vector. A feasible installation method is given for the real engineering realization of this proposed configuration. The performances of the novel configuration and another six configurations are comprehensively compared and analyzed. Simulation and experimentation are also conducted, and the results show that the orthogonal rotation configuration has the best reliability, accuracy and fault detection and isolation (FDI) performance when the number of gyros is nine. PMID:25076218

  5. Solutions on high-resolution multiple configuration system sensors

    NASA Astrophysics Data System (ADS)

    Liu, Hua; Ding, Quanxin; Guo, Chunjie; Zhou, Liwei

    2014-11-01

    For aim to achieve an improved resolution in modern image domain, a method of continuous zoom multiple configuration, with a core optics is attempt to establish model by novel principle on energy transfer and high accuracy localization, by which the system resolution can be improved with a level in nano meters. A comparative study on traditional vs modern methods can demonstrate that the dialectical relationship and their balance is important, among Merit function, Optimization algorithms and Model parameterization. The effect of system evaluated criterion that MTF, REA, RMS etc. can support our arguments qualitatively.

  6. Multiple objective optimization for active sensor management

    NASA Astrophysics Data System (ADS)

    Page, Scott F.; Dolia, Alexander N.; Harris, Chris J.; White, Neil M.

    2005-03-01

    The performance of a multi-sensor data fusion system is inherently constrained by the configuration of the given sensor suite. Intelligent or adaptive control of sensor resources has been shown to offer improved fusion performance in many applications. Common approaches to sensor management select sensor observation tasks that are optimal in terms of a measure of information. However, optimising for information alone is inherently sub-optimal as it does not take account of any other system requirements such as stealth or sensor power conservation. We discuss the issues relating to developing a suite of performance metrics for optimising multi-sensor systems and propose some candidate metrics. In addition it may not always be necessary to maximize information gain, in some cases small increases in information gain may take place at the cost of large sensor resource requirements. Additionally, the problems of sensor tasking and placement are usually treated separately, leading to a lack of coherency between sensor management frameworks. We propose a novel approach based on a high level decentralized information-theoretic sensor management architecture that unifies the processes of sensor tasking and sensor placement into a single framework. Sensors are controlled using a minimax multiple objective optimisation approach in order to address probability of target detection, sensor power consumption, and sensor survivability whilst maintaining a target estimation covariance threshold. We demonstrate the potential of the approach through simulation of a multi-sensor, target tracking scenario and compare the results with a single objective information based approach.

  7. Active spectral sensor evaluation under varying conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant stress has been estimated by spectral signature using both passive and active sensors. As optical sensors measure reflected light from a target, changes in illumination characteristics critically affect sensor response. Active sensors are of benefit in minimizing uncontrolled illumination effe...

  8. A new photopyroelectric scheme suitable for phase-transition investigations: The front configuration with semitransparent sensor

    NASA Astrophysics Data System (ADS)

    Dadarlat, D.; Frandas, A.; Marinelli, M.; Mercuri, F.; Bicanic, D.

    1995-07-01

    The theory of the front configuration with semitransparent sensor for a five layer photopyroelectric cell is presented. The particular cases suitable for phase-transition investigations are derived. An application to the study of the first-order phase transition of lauric fatty acid supports the validity of the theoretical model.

  9. Design and analysis of air acoustic vector-sensor configurations for two-dimensional geometry.

    PubMed

    Wajid, Mohd; Kumar, Arun; Bahl, Rajendar

    2016-05-01

    Acoustic vector-sensors (AVS) have been designed using the P-P method for different microphone configurations. These configurations have been used to project the acoustic intensity on the orthogonal axes through which the direction of arrival (DoA) of a sound source has been estimated. The analytical expressions for the DoA for different microphone configurations have been derived for two-dimensional geometry. Finite element method simulation using COMSOL-Multiphysics has been performed, where the microphone signals for AVS configurations have been recorded in free field conditions. The performance of all the configurations has been evaluated with respect to angular error and root-mean-square angular error. The simulation results obtained with ideal geometry for different configurations have been corroborated experimentally with prototype AVS realizations and also compared with microphone-array method, viz., Multiple Signal Classification and Generalized Cross Correlation. Experiments have been performed in an anechoic room using different prototype AVS configurations made from small size microphones. The DoA performance using analytical expressions, simulation studies, and experiments with prototype AVS in anechoic chamber are presented in the paper. The square and delta configurations are found to perform better in the absence and presence of noise, respectively. PMID:27250174

  10. Active and Passive Hybrid Sensor

    NASA Technical Reports Server (NTRS)

    Carswell, James R.

    2010-01-01

    A hybrid ocean wind sensor (HOWS) can map ocean vector wind in low to hurricane-level winds, and non-precipitating and precipitating conditions. It can acquire active and passive measurements through a single aperture at two wavelengths, two polarizations, and multiple incidence angles. Its low profile, compact geometry, and low power consumption permits installation on air craft platforms, including high-altitude unmanned aerial vehicles (UAVs).

  11. Active Targets For Capacitive Proximity Sensors

    NASA Technical Reports Server (NTRS)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Lightweight, low-power active targets devised for use with improved capacitive proximity sensors described in "Capacitive Proximity Sensor Has Longer Range" (GSC-13377), and "Capacitive Proximity Sensors With Additional Driven Shields" (GSC-13475). Active targets are short-distance electrostatic beacons; they generate known alternating electro-static fields used for alignment and/or to measure distances.

  12. Actively controlling coolant-cooled cold plate configuration

    DOEpatents

    Chainer, Timothy J.; Parida, Pritish R.

    2016-04-26

    Cooling apparatuses are provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The cooling apparatus includes the cold plate and a controller. The cold plate couples to one or more electronic components to be cooled, and includes an adjustable physical configuration. The controller dynamically varies the adjustable physical configuration of the cold plate based on a monitored variable associated with the cold plate or the electronic component(s) being cooled by the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the electronic component(s), and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the cold plate, the positioning of which may be adjusted based on the monitored variable.

  13. Method and apparatus for measuring surface changes, in porous materials, using multiple differently-configured acoustic sensors

    DOEpatents

    Hietala, Susan Leslie; Hietala, Vincent Mark; Tigges, Chris Phillip

    2001-01-01

    A method and apparatus for measuring surface changes, such as mass uptake at various pressures, in a thin-film material, in particular porous membranes, using multiple differently-configured acoustic sensors.

  14. Formation of active region and quiescent prominence magnetic field configurations

    NASA Technical Reports Server (NTRS)

    An, C.-H.; Bao, J. J.; Wu, S. T.

    1986-01-01

    To investigate the formation of prominences, researchers studied chromospheric mass injection into an overlying coronal dipole magnetic field using a 2-D ideal magnetohydrodynamic (MHD) numerical model. Researchers propose that active region prominences are formed by chromospheric plasmas injected directly into the overlying coronal magnetic field and that quiescent prominences are formed by plasmas evaporated at the interface between spicules and corona. Hence, for the simulation of an active region prominence magnetic field we inject the mass from one side, but use a symmetric mass injection to form a quiescent prominence field configuration. Researchers try to find optimum conditions for the formation of Kippenhahn-Schuluter(K-S)type field configuration for stable support of the injection plasmas. They find that the formation of K-S type field configuration by mass injection requires a delicate balance between injection velocity, density, and overlying magnetic fields. These results may explain why a prominence does not form on every neutral line.

  15. Active thermal isolation for temperature responsive sensors

    NASA Technical Reports Server (NTRS)

    Martinson, Scott D. (Inventor); Gray, David L. (Inventor); Carraway, Debra L. (Inventor); Reda, Daniel C. (Inventor)

    1994-01-01

    A temperature responsive sensor is located in the airflow over the specified surface of a body and is maintained at a constant temperature. An active thermal isolator is located between this temperature responsive sensor and the specified surface of the body. The temperature of this isolator is controlled to reduce conductive heat flow from the temperature responsive sensor to the body. This temperature control includes: (1) operating the isolator at the same temperature as the constant temperature of the sensor and (2) establishing a fixed boundary temperature which is either less than or equal to or slightly greater than the sensor constant temperature.

  16. Actively controlling coolant-cooled cold plate configuration

    SciTech Connect

    Chainer, Timothy J.; Parida, Pritish R.

    2015-07-28

    A method is provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The method includes: monitoring a variable associated with at least one of the coolant-cooled cold plate or one or more electronic components being cooled by the cold plate; and dynamically varying, based on the monitored variable, a physical configuration of the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the one or more electronic components, and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the coolant-cooled cold plate, the positioning of which may be adjusted based on the monitored variable.

  17. Active sensor assessment of corn nitrogen status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of active sensor measurements of in-season corn (Zea mays L.) nitrogen (N) status for directing spatially-variable N applications has been advocated to improve N use efficiency. However, first it is necessary to confirm that active sensors can reliably assess corn N status. Our research goals we...

  18. Activity Recognition on Streaming Sensor Data

    PubMed Central

    Krishnan, Narayanan C; Cook, Diane J

    2012-01-01

    Many real-world applications that focus on addressing needs of a human, require information about the activities being performed by the human in real-time. While advances in pervasive computing have lead to the development of wireless and non-intrusive sensors that can capture the necessary activity information, current activity recognition approaches have so far experimented on either a scripted or pre-segmented sequence of sensor events related to activities. In this paper we propose and evaluate a sliding window based approach to perform activity recognition in an on line or streaming fashion; recognizing activities as and when new sensor events are recorded. To account for the fact that different activities can be best characterized by different window lengths of sensor events, we incorporate the time decay and mutual information based weighting of sensor events within a window. Additional contextual information in the form of the previous activity and the activity of the previous window is also appended to the feature describing a sensor window. The experiments conducted to evaluate these techniques on real-world smart home datasets suggests that combining mutual information based weighting of sensor events and adding past contextual information into the feature leads to best performance for streaming activity recognition. PMID:24729780

  19. Activity Recognition on Streaming Sensor Data.

    PubMed

    Krishnan, Narayanan C; Cook, Diane J

    2014-02-01

    Many real-world applications that focus on addressing needs of a human, require information about the activities being performed by the human in real-time. While advances in pervasive computing have lead to the development of wireless and non-intrusive sensors that can capture the necessary activity information, current activity recognition approaches have so far experimented on either a scripted or pre-segmented sequence of sensor events related to activities. In this paper we propose and evaluate a sliding window based approach to perform activity recognition in an on line or streaming fashion; recognizing activities as and when new sensor events are recorded. To account for the fact that different activities can be best characterized by different window lengths of sensor events, we incorporate the time decay and mutual information based weighting of sensor events within a window. Additional contextual information in the form of the previous activity and the activity of the previous window is also appended to the feature describing a sensor window. The experiments conducted to evaluate these techniques on real-world smart home datasets suggests that combining mutual information based weighting of sensor events and adding past contextual information into the feature leads to best performance for streaming activity recognition. PMID:24729780

  20. Absolute configuration and antimicrobial activity of acylhomoserine lactones.

    PubMed

    Pomini, Armando M; Marsaioli, Anita J

    2008-06-01

    (S)-N-Heptanoylhomoserine lactone is an uncommon acyl odd-chain natural product employed by many Gram-negative bacteria as a signaling substance in chemical communication mechanisms known as quorum sensing. The absolute configuration determination of the metabolite produced by the phytopathogen Pantoea ananatis Serrano is reported herein. As with all other substances of this class, the lactone moiety possesses S configuration, corroborating the hypothesis that it shares the same biosynthetic pathway as the (S)-N-hexanoylhomoserine lactone and also that some LuxI homologues can accept both hexanoyl- and heptanoyl-ACP as precursors. Evaluation of the antimicrobial activity of enantiomeric acylhomoserine lactones against three Gram-positive bacteria (Bacillus cereus, B. subtilis, and Staphylococcus aureus) revealed important features between absolute configuration and antimicrobial activity. The N-heptanoylhomoserine lactone was considerably less active than the 3-oxo derivatives. Surprisingly, non-natural (R)-N-(3-oxo-octanoyl)homoserine lactone was as active as the S enantiomer against B. cereus, while the synthetic racemic product was less active than either enantiomer. PMID:18465897

  1. Non-standard electromagnetic induction sensor configurations: Evaluating sensitivities and applicability

    NASA Astrophysics Data System (ADS)

    Guillemoteau, Julien; Tronicke, Jens

    2015-07-01

    For near surface geophysical surveys, small-fixed offset loop-loop electromagnetic induction (EMI) sensors are usually placed parallel to the ground surface (i.e., both loops are at the same height above ground). In this study, we evaluate the potential of making measurements with a system that is not parallel to the ground; i.e., by positioning the system at different inclinations with respect to ground surface. First, we present the Maxwell theory for inclined magnetic dipoles over a homogeneous half space. By analyzing the sensitivities of such configurations, we show that varying the angle of the system would result in improved imaging capabilities. For example, we show that acquiring data with a vertical system allows detection of a conductive body with a better lateral resolution compared to data acquired using standard horizontal configurations. The synthetic responses are presented for a heterogeneous medium and compared to field data acquired in the historical Park Sanssouci in Potsdam, Germany. After presenting a detailed sensitivity analysis and synthetic examples of such ground conductivity measurements, we suggest a new strategy of acquisition that allows to better estimate the true distribution of electrical conductivity using instruments with a fixed, small offset between the loops. This strategy is evaluated using field data collected at a well-constrained test-site in Horstwalde (Germany). Here, the target buried utility pipes are best imaged using vertical system configurations demonstrating the potential of our approach for typical applications.

  2. Active Sensing and Its Application to Sensor Node Reconfiguration

    PubMed Central

    Lee, Sooyong

    2014-01-01

    This paper presents a perturbation/correlation-based active sensing method and its application to sensor node configuration for environment monitoring. Sensor networks are widely used as data measurement tools, especially in dangerous environments. For large scale environment monitoring, a large number of nodes is required. For optimal measurements, the placement of nodes is very important. Nonlinear spring force-based configuration is introduced. Perturbation/correlation-based estimation of the gradient is developed and it is much more robust because it does not require any differentiation. An algorithm for tuning the stiffness using the estimated gradient for node reconfiguration is presented. The performance of the proposed algorithm is discussed with simulation results. PMID:25299949

  3. Intruder Activity Analysis under Unreliable Sensor Networks

    SciTech Connect

    Tae-Sic Yoo; Humberto E. Garcia

    2007-09-01

    This paper addresses the problem of counting intruder activities within a monitored domain by a sensor network. The deployed sensors are unreliable. We characterize imperfect sensors with misdetection and false-alarm probabilities. We model intruder activities with Markov Chains. A set of Hidden Markov Models (HMM) models the imperfect sensors and intruder activities to be monitored. A novel sequential change detection/isolation algorithm is developed to detect and isolate a change from an HMM representing no intruder activity to another HMM representing some intruder activities. Procedures for estimating the entry time and the trace of intruder activities are developed. A domain monitoring example is given to illustrate the presented concepts and computational procedures.

  4. Preparation of the spacer for narrow electrode gap configuration in ionization-based gas sensor

    SciTech Connect

    Saheed, Mohamed Shuaib Mohamed; Mohamed, Norani Muti; Burhanudin, Zainal Arif

    2012-09-26

    Carbon nanotubes (CNTs) have started to be developed as the sensing element for ionization-based gas sensors due to the demand for improved sensitivity, selectivity, stability and other sensing properties beyond what can be offered by the conventional ones. Although these limitations have been overcome, the problems still remain with the conventional ionization-based gas sensors in that they are bulky and operating with large breakdown voltage and high temperature. Recent studies have shown that the breakdown voltage can be reduced by using nanostructured electrodes and narrow electrode gap. Nanostructured electrode in the form of aligned CNTs array with evenly distributed nanotips can enhance the linear electric field significantly. The later is attributed to the shorter conductivity path through narrow electrode gap. The paper presents the study on the design consideration in order to realize ionization based gas sensor using aligned carbon nanotubes array in an optimum sensor configuration with narrow electrode gap. Several deposition techniques were studied to deposit the spacer, the key component that can control the electrode gap. Plasma spray deposition, electron beam deposition and dry oxidation method were employed to obtain minimum film thickness around 32 {mu}m. For plasma spray method, sand blasting process is required in order to produce rough surface for strong bonding of the deposited film onto the surface. Film thickness, typically about 39 {mu}m can be obtained. For the electron beam deposition and dry oxidation, the film thickness is in the range of nanometers and thus unsuitable to produce the spacer. The deposited multilayer film consisting of copper, alumina and ferum on which CNTs array will be grown was found to be removed during the etching process. This is attributed to the high etching rate on the thin film which can be prevented by reducing the rate and having a thicker conductive copper film.

  5. Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

    2014-11-01

    We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

  6. Active thermal isolation for temperature responsive sensors

    NASA Technical Reports Server (NTRS)

    Martinson, Scott D. (Inventor); Gray, David L. (Inventor); Carraway, Debra L. (Inventor); Reda, Daniel C. (Inventor)

    1994-01-01

    The detection of flow transition between laminar and turbulent flow and of shear stress or skin friction of airfoils is important in basic research for validation of airfoil theory and design. These values are conventionally measured using hot film nickel sensors deposited on a polyimide substrate. The substrate electrically insulates the sensor and underlying airfoil but is prevented from thermally isolating the sensor by thickness constraints necessary to avoid flow contamination. Proposed heating of the model surface is difficult to control, requires significant energy expenditures, and may alter the basic flow state of the airfoil. A temperature responsive sensor is located in the airflow over the specified surface of a body and is maintained at a constant temperature. An active thermal isolator is located between this temperature responsive sensor and the specific surface of the body. The total thickness of the isolator and sensor avoid any contamination of the flow. The temperature of this isolator is controlled to reduce conductive heat flow from the temperature responsive sensor to the body. This temperature control includes (1) operating the isolator at the same temperature as the constant temperature of the sensor; and (2) establishing a fixed boundary temperature which is either less than or equal to, or slightly greater than the sensor constant temperature. The present invention accordingly thermally isolates a temperature responsive sensor in an energy efficient, controllable manner while avoiding any contamination of the flow.

  7. BK channels: multiple sensors, one activation gate.

    PubMed

    Yang, Huanghe; Zhang, Guohui; Cui, Jianmin

    2015-01-01

    Ion transport across cell membranes is essential to cell communication and signaling. Passive ion transport is mediated by ion channels, membrane proteins that create ion conducting pores across cell membrane to allow ion flux down electrochemical gradient. Under physiological conditions, majority of ion channel pores are not constitutively open. Instead, structural region(s) within these pores breaks the continuity of the aqueous ion pathway, thereby serves as activation gate(s) to control ions flow in and out. To achieve spatially and temporally regulated ion flux in cells, many ion channels have evolved sensors to detect various environmental stimuli or the metabolic states of the cell and trigger global conformational changes, thereby dynamically operate the opening and closing of their activation gate. The sensors of ion channels can be broadly categorized as chemical sensors and physical sensors to respond to chemical (such as neural transmitters, nucleotides and ions) and physical (such as voltage, mechanical force and temperature) signals, respectively. With the rapidly growing structural and functional information of different types of ion channels, it is now critical to understand how ion channel sensors dynamically control their gates at molecular and atomic level. The voltage and Ca(2+) activated BK channels, a K(+) channel with an electrical sensor and multiple chemical sensors, provide a unique model system for us to understand how physical and chemical energy synergistically operate its activation gate. PMID:25705194

  8. BK channels: multiple sensors, one activation gate

    PubMed Central

    Yang, Huanghe; Zhang, Guohui; Cui, Jianmin

    2015-01-01

    Ion transport across cell membranes is essential to cell communication and signaling. Passive ion transport is mediated by ion channels, membrane proteins that create ion conducting pores across cell membrane to allow ion flux down electrochemical gradient. Under physiological conditions, majority of ion channel pores are not constitutively open. Instead, structural region(s) within these pores breaks the continuity of the aqueous ion pathway, thereby serves as activation gate(s) to control ions flow in and out. To achieve spatially and temporally regulated ion flux in cells, many ion channels have evolved sensors to detect various environmental stimuli or the metabolic states of the cell and trigger global conformational changes, thereby dynamically operate the opening and closing of their activation gate. The sensors of ion channels can be broadly categorized as chemical sensors and physical sensors to respond to chemical (such as neural transmitters, nucleotides and ions) and physical (such as voltage, mechanical force and temperature) signals, respectively. With the rapidly growing structural and functional information of different types of ion channels, it is now critical to understand how ion channel sensors dynamically control their gates at molecular and atomic level. The voltage and Ca2+ activated BK channels, a K+ channel with an electrical sensor and multiple chemical sensors, provide a unique model system for us to understand how physical and chemical energy synergistically operate its activation gate. PMID:25705194

  9. A methodology to identify representative configurations of sensors for monitoring soil moisture.

    PubMed

    Rivera, Diego; Granda, Stalin; Arumí, José Luis; Sandoval, Marco; Billib, Max

    2012-11-01

    Soil moisture is the key link among hydroecological compartments, responding dynamically to sequences of atmospheric processes and management conditions and modulating physical, chemical, and biological processes in the soil. Currently, there are a variety of monitoring techniques to measure, directly or indirectly, the soil moisture. However, some practical issues remain open like the definition a priori of the number, location and depth of the monitoring points, and the impact of failing or poor performance soil moisture sensors. Here, we present a set of techniques, namely Δθ time series, wavelet filtering, and time stability, to identify representative points and monitoring depths through an analysis of hourly soil moisture time series for different configuration of the monitoring network. We used real data from a monitoring network consisting of seven monitoring points, each one with four EC-5 probes (Decagon Devices Inc., Pullman, WA) at 20, 40, 60, and 100 cm. The use of simple time series of Δθ allowed us to assess the spatiotemporal influence of the monitoring points, while the wavelet periodograms allowed us to get insight about the response of the monitoring points at different time scales. Both methods are easy to implement or adapt to specific conditions, being coherent to the results derived from time stability analysis. For our case study, we concluded that we could reallocate 16 sensors (out of 28) without a significant loss of information. However, the final decision strongly relies on a deep knowledge of the site features and the objectives of the monitoring network. PMID:22146817

  10. Cardiac Care Assistance using Self Configured Sensor Network—a Remote Patient Monitoring System

    NASA Astrophysics Data System (ADS)

    Sarma Dhulipala, V. R.; Kanagachidambaresan, G. R.

    2014-04-01

    Pervasive health care systems are used to monitor patients remotely without disturbing the normal day-to-day activities in real-time. Wearable physiological sensors required to monitor various significant ecological parameters of the patients are connected to Body Central Unit (BCU). Body Sensor Network (BSN) updates data in real-time and are designed to transmit alerts against abnormalities which enables quick response by medical units in case of an emergency. BSN helps monitoring patient without any need for attention to the subject. BSN helps in reducing the stress and strain caused by hospital environment. In this paper, mathematical models for heartbeat signal, electro cardio graph (ECG) signal and pulse rate are introduced. These signals are compared and their RMS difference-fast Fourier transforms (PRD-FFT) are processed. In the context of cardiac arrest, alert messages of these parameters and first aid for post-surgical operations has been suggested.

  11. Computational optimization of the configuration of a spatially resolved spectroscopy sensor for milk analysis.

    PubMed

    Watté, Rodrigo; Aernouts, Ben; Van Beers, Robbe; Postelmans, Annelies; Saeys, Wouter

    2016-04-21

    A global optimizer has been developed, capable of computing the optimal configuration in a probe for spatially resolved reflectance spectroscopy (SRS). The main objective is to minimize the number of detection fibers, while maintaining an accurate estimation of both absorption and scattering profiles. Multiple fibers are necessary to robustify the estimation of optical properties against noise, which is typically present in the measured signals and influences the accuracy of the inverse estimation. The optimizer is based on a robust metamodel-based inverse estimation of the absorption coefficient and a reduced scattering coefficient from the acquired SRS signals. A genetic algorithm is used to evaluate the effect of the fiber placement on the performance of the inverse estimator to find the bulk optical properties of raw milk. The algorithm to find the optimal fiber placement was repeatedly executed for cases with a different number of detection fibers, ranging from 3 to 30. Afterwards, the optimal designs for each considered number of fibers were compared based on their performance in separating the absorption and scattering properties, and the significance of the differences was tested. A sensor configuration with 13 detection fibers was found to be the combination with the lowest number of fibers which provided an estimation performance which was not significantly worse than the one obtained with the best design (30 detection fibers). This design resulted in the root mean squared error of prediction (RMSEP) of 1.411 cm(-1) (R(2) = 0.965) for the estimation of the bulk absorption coefficient values, and 0.382 cm(-1) (R(2) = 0.996) for the reduced scattering coefficient values. PMID:27026600

  12. Optimized geometric configuration of active ring laser gyroscopes

    NASA Astrophysics Data System (ADS)

    Gormley, John; Salloum, Tony

    2016-05-01

    We present a thorough derivation of the Sagnac effect for a ring laser gyroscope of any arbitrary polygonal configuration. We determine optimized alternative geometric configurations for the mirrors. The simulations incur the implementation of a lasing medium with the standard square system, triangular, pentagonal, and oblongated square configuration (diamond). Simulations of possible new geometric configurations are considered, as well as the possibility of adjusting the concavity of the mirrors.

  13. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration

    PubMed Central

    Hao, Wenchang; Liu, Jiuling; Liu, Minghua; Liang, Yong; He, Shitang

    2016-01-01

    The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW) sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM) approach was established to extract the coupling-of-modes (COM) parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of an R-SAW resonator by a P-matrix cascading technique. Cascading the P-matrixes of unloaded areas with mass loaded areas, the sensitivity for different sensitive areas was obtained by analyzing the frequency shift. The performance of the sensitivity analysis was confirmed by the measured responses from the silicon dioxide (SiO2) deposited on different sensitive areas of R-SAW resonators. It is shown that the mass sensitivity varies strongly for different sensitive areas, and the optimal sensitive area lies towards the center of the device. PMID:27104540

  14. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration.

    PubMed

    Hao, Wenchang; Liu, Jiuling; Liu, Minghua; Liang, Yong; He, Shitang

    2016-01-01

    The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW) sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM) approach was established to extract the coupling-of-modes (COM) parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of an R-SAW resonator by a P-matrix cascading technique. Cascading the P-matrixes of unloaded areas with mass loaded areas, the sensitivity for different sensitive areas was obtained by analyzing the frequency shift. The performance of the sensitivity analysis was confirmed by the measured responses from the silicon dioxide (SiO₂) deposited on different sensitive areas of R-SAW resonators. It is shown that the mass sensitivity varies strongly for different sensitive areas, and the optimal sensitive area lies towards the center of the device. PMID:27104540

  15. A Diagnoser Algorithm for Anomaly Detection in DEDS under Partial Unreliable Observations: Characterization and Inclusion in Sensor Configuration Optimizaton

    SciTech Connect

    Wen-Chiao Lin; Humberto Garcia; Tae-Sic Yoo

    2013-03-01

    Complex engineering systems have to be carefully monitored to meet demanding performance requirements, including detecting anomalies in their operations. There are two major monitoring challenges for these systems. The first challenge is that information collected from the monitored system is often partial and/or unreliable, in the sense that some occurred events may not be reported and/or may be reported incorrectly (e.g., reported as another event). The second is that anomalies often consist of sequences of event patterns separated in space and time. This paper introduces and analyzes a diagnoser algorithm that meets these challenges for detecting and counting occurrences of anomalies in engineering systems. The proposed diagnoser algorithm assumes that models are available for characterizing plant operations (via stochastic automata) and sensors (via probabilistic mappings) used for reporting partial and unreliable information. Methods for analyzing the effects of model uncertainties on the diagnoser performance are also discussed. In order to select configurations that reduce sensor costs, while satisfying diagnoser performance requirements, a sensor configuration selection algorithm developed in previous work is then extended for the proposed diagnoser algorithm. The proposed algorithms and methods are then applied to a multi-unit-operation system, which is derived from an actual facility application. Results show that the proposed diagnoser algorithm is able to detect and count occurrences of anomalies accurately and that its performance is robust to model uncertainties. Furthermore, the sensor configuration selection algorithm is able to suggest optimal sensor configurations with significantly reduced costs, while still yielding acceptable performance for counting the occurrences of anomalies.

  16. Characteristics of active spectral sensor for plant sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant stress has been estimated by spectral signature using both passive and active sensors. As optical sensors measure reflected light from a target, changes in illumination conditions critically affect sensor response. Active spectral sensors minimize the illumination effects by producing their ...

  17. Functionalized active-nucleus complex sensor

    DOEpatents

    Pines, Alexander; Wemmer, David E.; Spence, Megan; Rubin, Seth

    2003-11-25

    A functionalized active-nucleus complex sensor that selectively associates with one or more target species, and a method for assaying and screening for one or a plurality of target species utilizing one or a plurality of functionalized active-nucleus complexes with at least two of the functionalized active-nucleus complexes having an attraction affinity to different corresponding target species. The functionalized active-nucleus complex has an active-nucleus and a targeting carrier. The method involves functionalizing an active-nucleus, for each functionalized active-nucleus complex, by incorporating the active-nucleus into a macromolucular or molecular complex that is capable of binding one of the target species and then bringing the macromolecular or molecular complexes into contact with the target species and detecting the occurrence of or change in a nuclear magnetic resonance signal from each of the active-nuclei in each of the functionalized active-nucleus complexes.

  18. Liquid sensor based on high-Q slot photonic crystal cavity in silicon-on-insulator configuration.

    PubMed

    Caër, Charles; Serna-Otálvaro, Samuel F; Zhang, Weiwei; Le Roux, Xavier; Cassan, Eric

    2014-10-15

    We present the realization of an optical sensor based on an infiltrated high-Q slot photonic crystal cavity in a nonfreestanding membrane configuration. Successive infiltrations by liquids with refractive indices ranging from 1.345 to 1.545 yield a sensitivity S of 235 nm/RIU (refractive index unit), while the Q-factor is comprised between 8000 and 25,000, giving a sensor figure of merit up to 3700. This sensor has a detection limit of 1.25×10⁻⁵. The operation of this device on a silicon-on-insulator (SOI) substrate allows a straightforward integration in the silicon photonics platform, while providing a compliant mechanical stability. PMID:25361086

  19. Ontological Problem-Solving Framework for Dynamically Configuring Sensor Systems and Algorithms

    PubMed Central

    Qualls, Joseph; Russomanno, David J.

    2011-01-01

    The deployment of ubiquitous sensor systems and algorithms has led to many challenges, such as matching sensor systems to compatible algorithms which are capable of satisfying a task. Compounding the challenges is the lack of the requisite knowledge models needed to discover sensors and algorithms and to subsequently integrate their capabilities to satisfy a specific task. A novel ontological problem-solving framework has been designed to match sensors to compatible algorithms to form synthesized systems, which are capable of satisfying a task and then assigning the synthesized systems to high-level missions. The approach designed for the ontological problem-solving framework has been instantiated in the context of a persistence surveillance prototype environment, which includes profiling sensor systems and algorithms to demonstrate proof-of-concept principles. Even though the problem-solving approach was instantiated with profiling sensor systems and algorithms, the ontological framework may be useful with other heterogeneous sensing-system environments. PMID:22163793

  20. An Active Sensor Nitrogen Application Algorithm for Corn Using a Chlorophyll Meter Based Sufficiency Index Concept

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Traditional N fertilizer management schemes for U.S. corn production systems have resulted in low N use efficiency, reduced water quality, and considerable public debate regarding N use in crop production. We have built a prototype high clearance N applicator configured with active sensors, controll...

  1. Monolithic Active-Pixel Infrared Sensors

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R.; Cunningham, Thomas J.; Krabach, Timothy N.; Staller, Craig O.

    1995-01-01

    Monolithic arrays of active-pixel junction field-effect (JFET) devices made from InGaAs proposed for use as imaging sensors sensitive to light in visible and short-wavelength infrared parts of electromagnetic spectrum. Each pixel of such array comprises photodetector monolithically integrated with JFET output-amplifier circuit of source-follower type - structure similar to charge-coupled device (CCD). Sizes of instruments reduced because large cooling systems not needed.

  2. SensorWeb 3G: Extending On-Orbit Sensor Capabilities to Enable Near Realtime User Configurability

    NASA Technical Reports Server (NTRS)

    Mandl, Daniel; Cappelaere, Pat; Frye, Stuart; Sohlberg, Rob; Ly, Vuong; Chien, Steve; Tran, Daniel; Davies, Ashley; Sullivan, Don; Ames, Troy; Witt, Ken; Stanley, Jason

    2010-01-01

    This research effort prototypes an implementation of a standard interface, Web Coverage Processing Service (WCPS), which is an Open Geospatial Consortium(OGC) standard, to enable users to define, test, upload and execute algorithms for on-orbit sensor systems. The user is able to customize on-orbit data products that result from raw data streaming from an instrument. This extends the SensorWeb 2.0 concept that was developed under a previous Advanced Information System Technology (AIST) effort in which web services wrap sensors and a standardized Extensible Markup Language (XML) based scripting workflow language orchestrates processing steps across multiple domains. SensorWeb 3G extends the concept by providing the user controls into the flight software modules associated with on-orbit sensor and thus provides a degree of flexibility which does not presently exist. The successful demonstrations to date will be presented, which includes a realistic HyspIRI decadal mission testbed. Furthermore, benchmarks that were run will also be presented along with future demonstration and benchmark tests planned. Finally, we conclude with implications for the future and how this concept dovetails into efforts to develop "cloud computing" methods and standards.

  3. Physical Human Activity Recognition Using Wearable Sensors.

    PubMed

    Attal, Ferhat; Mohammed, Samer; Dedabrishvili, Mariam; Chamroukhi, Faicel; Oukhellou, Latifa; Amirat, Yacine

    2015-01-01

    This paper presents a review of different classification techniques used to recognize human activities from wearable inertial sensor data. Three inertial sensor units were used in this study and were worn by healthy subjects at key points of upper/lower body limbs (chest, right thigh and left ankle). Three main steps describe the activity recognition process: sensors' placement, data pre-processing and data classification. Four supervised classification techniques namely, k-Nearest Neighbor (k-NN), Support Vector Machines (SVM), Gaussian Mixture Models (GMM), and Random Forest (RF) as well as three unsupervised classification techniques namely, k-Means, Gaussian mixture models (GMM) and Hidden Markov Model (HMM), are compared in terms of correct classification rate, F-measure, recall, precision, and specificity. Raw data and extracted features are used separately as inputs of each classifier. The feature selection is performed using a wrapper approach based on the RF algorithm. Based on our experiments, the results obtained show that the k-NN classifier provides the best performance compared to other supervised classification algorithms, whereas the HMM classifier is the one that gives the best results among unsupervised classification algorithms. This comparison highlights which approach gives better performance in both supervised and unsupervised contexts. It should be noted that the obtained results are limited to the context of this study, which concerns the classification of the main daily living human activities using three wearable accelerometers placed at the chest, right shank and left ankle of the subject. PMID:26690450

  4. Data assimilation with in situ soil moisture observations: what spatial configuration of the sensor network should be considered?

    NASA Astrophysics Data System (ADS)

    De Vleeschouwer, Niels; Verhoest, Niko E. C.; Pauwels, Valentijn R. N.

    2016-04-01

    Continuously monitoring soil moisture in a permanent in situ network can yield an interesting observation product for hydrological data assimilation. Those in situ observations can be characterised by some major advantages such as a fine temporal resolution, a large vertical extent, the small impact of land cover on the observation error, etc. Because of the typical small integration volume of in situ measurements and the often large spacing between monitoring locations, only a small part of the modelling domain can be directly observed. Therefore a first important question to answer is whether spatially sparse in-situ soil moisture observations contain a sufficient data representativeness to successfully update the largely unobserved spatial extent of a distributed hydrological model. Furthermore, the spatial configuration of the sensors remains unaltered through time. Consequently it is interesting to assess the sensitivity of the spatial configuration of the sensors regarding the data assimilation performance. This allows for answering a second question: is it possible to reduce the number of sensors by optimising the design of the in situ network whilst maintaining the same level of assimilation performance? To bring added value in practice, one should be able to identify optimal network configurations using prior available model input data and/or open loop statistics, i.e. statistics derived from a model run without data assimilation. In this study the meso-scale catchment of the Bellebeek (±100 km²) in Belgium is modelled. The above-mentioned questions are addressed by means of a synthetic data assimilation framework using the ensemble Kalman filter. It can be concluded that the network configuration can indeed have a significant influence on the assimilation performance. Furthermore, preliminary results indicate that certain open loop statistics can be used as a network performance predictor. More in particular, it was examined whether the information

  5. Evaluation of a fault tolerant system for an integrated avionics sensor configuration with TSRV flight data

    NASA Technical Reports Server (NTRS)

    Caglayan, A. K.; Godiwala, P. M.

    1985-01-01

    The performance analysis results of a fault inferring nonlinear detection system (FINDS) using sensor flight data for the NASA ATOPS B-737 aircraft in a Microwave Landing System (MLS) environment is presented. First, a statistical analysis of the flight recorded sensor data was made in order to determine the characteristics of sensor inaccuracies. Next, modifications were made to the detection and decision functions in the FINDS algorithm in order to improve false alarm and failure detection performance under real modelling errors present in the flight data. Finally, the failure detection and false alarm performance of the FINDS algorithm were analyzed by injecting bias failures into fourteen sensor outputs over six repetitive runs of the five minute flight data. In general, the detection speed, failure level estimation, and false alarm performance showed a marked improvement over the previously reported simulation runs. In agreement with earlier results, detection speed was faster for filter measurement sensors soon as MLS than for filter input sensors such as flight control accelerometers.

  6. Autonomous Sun-Direction Estimation Using Partially Underdetermined Coarse Sun Sensor Configurations

    NASA Astrophysics Data System (ADS)

    O'Keefe, Stephen A.

    In recent years there has been a significant increase in interest in smaller satellites as lower cost alternatives to traditional satellites, particularly with the rise in popularity of the CubeSat. Due to stringent mass, size, and often budget constraints, these small satellites rely on making the most of inexpensive hardware components and sensors, such as coarse sun sensors (CSS) and magnetometers. More expensive high-accuracy sun sensors often combine multiple measurements, and use specialized electronics, to deterministically solve for the direction of the Sun. Alternatively, cosine-type CSS output a voltage relative to the input light and are attractive due to their very low cost, simplicity to manufacture, small size, and minimal power consumption. This research investigates using coarse sun sensors for performing robust attitude estimation in order to point a spacecraft at the Sun after deployment from a launch vehicle, or following a system fault. As an alternative to using a large number of sensors, this thesis explores sun-direction estimation techniques with low computational costs that function well with underdetermined sets of CSS. Single-point estimators are coupled with simultaneous nonlinear control to achieve sun-pointing within a small percentage of a single orbit despite the partially underdetermined nature of the sensor suite. Leveraging an extensive analysis of the sensor models involved, sequential filtering techniques are shown to be capable of estimating the sun-direction to within a few degrees, with no a priori attitude information and using only CSS, despite the significant noise and biases present in the system. Detailed numerical simulations are used to compare and contrast the performance of the five different estimation techniques, with and without rate gyro measurements, their sensitivity to rate gyro accuracy, and their computation time. One of the key concerns with reducing the number of CSS is sensor degradation and failure. In

  7. Active pixel sensors with substantially planarized color filtering elements

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor); Kemeny, Sabrina E. (Inventor)

    1999-01-01

    A semiconductor imaging system preferably having an active pixel sensor array compatible with a CMOS fabrication process. Color-filtering elements such as polymer filters and wavelength-converting phosphors can be integrated with the image sensor.

  8. In-line monitoring of particle size in a fluid bed granulator: investigations concerning positioning and configuration of the sensor.

    PubMed

    Roßteuscher-Carl, Katrin; Fricke, Sabine; Hacker, Michael C; Schulz-Siegmund, Michaela

    2014-05-15

    According to the ICH Q8 guideline, analytic technologies (PAT) are important tools for characterization and optimization of pharmaceutical manufacturing processes. Particle size as a critical quality attribute for granules is therefore an important parameter that should be monitored during the fluid bed granulation process. This work focusses on optimizing position and configuration of an SFT-sensor for the in-line measurement of particle size distribution in a Glatt GPCG 3 fluid bed granulator. As model-substances, different grades of microcrystalline cellulose were used. The in-line measured particle size and particle rate in the sensor were evaluated. A sensor position in the deceleration zone of the granulator was found to be promising for in-line particle size measurement. Most reliable data were generated in this position when the probe was placed in a distance of 11cm from the chamber wall to avoid bias by the inlet air stream. No major influence of rotation angle of the probe was found in this position. Furthermore, an entire fluid bed granulation process was successfully monitored with the sensor installed in the optimized setting. PMID:24589125

  9. Physical Human Activity Recognition Using Wearable Sensors

    PubMed Central

    Attal, Ferhat; Mohammed, Samer; Dedabrishvili, Mariam; Chamroukhi, Faicel; Oukhellou, Latifa; Amirat, Yacine

    2015-01-01

    This paper presents a review of different classification techniques used to recognize human activities from wearable inertial sensor data. Three inertial sensor units were used in this study and were worn by healthy subjects at key points of upper/lower body limbs (chest, right thigh and left ankle). Three main steps describe the activity recognition process: sensors’ placement, data pre-processing and data classification. Four supervised classification techniques namely, k-Nearest Neighbor (k-NN), Support Vector Machines (SVM), Gaussian Mixture Models (GMM), and Random Forest (RF) as well as three unsupervised classification techniques namely, k-Means, Gaussian mixture models (GMM) and Hidden Markov Model (HMM), are compared in terms of correct classification rate, F-measure, recall, precision, and specificity. Raw data and extracted features are used separately as inputs of each classifier. The feature selection is performed using a wrapper approach based on the RF algorithm. Based on our experiments, the results obtained show that the k-NN classifier provides the best performance compared to other supervised classification algorithms, whereas the HMM classifier is the one that gives the best results among unsupervised classification algorithms. This comparison highlights which approach gives better performance in both supervised and unsupervised contexts. It should be noted that the obtained results are limited to the context of this study, which concerns the classification of the main daily living human activities using three wearable accelerometers placed at the chest, right shank and left ankle of the subject. PMID:26690450

  10. Active Pixel Sensors: Are CCD's Dinosaurs?

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R.

    1993-01-01

    Charge-coupled devices (CCD's) are presently the technology of choice for most imaging applications. In the 23 years since their invention in 1970, they have evolved to a sophisticated level of performance. However, as with all technologies, we can be certain that they will be supplanted someday. In this paper, the Active Pixel Sensor (APS) technology is explored as a possible successor to the CCD. An active pixel is defined as a detector array technology that has at least one active transistor within the pixel unit cell. The APS eliminates the need for nearly perfect charge transfer -- the Achilles' heel of CCDs. This perfect charge transfer makes CCD's radiation 'soft,' difficult to use under low light conditions, difficult to manufacture in large array sizes, difficult to integrate with on-chip electronics, difficult to use at low temperatures, difficult to use at high frame rates, and difficult to manufacture in non-silicon materials that extend wavelength response.

  11. Configuration studies for active electrostatic space radiation shielding

    NASA Astrophysics Data System (ADS)

    Joshi, Ravindra P.; Qiu, Hao; Tripathi, Ram K.

    2013-07-01

    Developing successful and optimal solutions to mitigating the hazards of severe space radiation in deep space long duration missions is critical for the success of deep-space explorations. Space crews traveling aboard interplanetary spacecraft will be exposed to a constant flux of galactic cosmic rays (GCR), as well as intense fluxes of charged particles during solar particle events (SPEs). A recent report (Tripathi et al., Adv. Space Res. 42 (2008) 1043-1049), had explored the feasibility of using electrostatic shielding in concert with the state-of-the-art materials shielding technologies. Here we continue to extend the electrostatic shielding strategy and quantitatively examine a different configuration based on multiple toroidal rings. Our results show that SPE radiation can almost be eliminated by these electrostatic configurations. Also, penetration probabilities for novel structures such as toroidal rings are shown to be substantially reduced as compared to the simpler all-sphere geometries. More interestingly, the dimensions and aspect ratio of the toroidal rings could be altered and optimized to achieve an even higher degree of radiation protection.

  12. Abnormal Activity Detection Using Pyroelectric Infrared Sensors

    PubMed Central

    Luo, Xiaomu; Tan, Huoyuan; Guan, Qiuju; Liu, Tong; Zhuo, Hankz Hankui; Shen, Baihua

    2016-01-01

    Healthy aging is one of the most important social issues. In this paper, we propose a method for abnormal activity detection without any manual labeling of the training samples. By leveraging the Field of View (FOV) modulation, the spatio-temporal characteristic of human activity is encoded into low-dimension data stream generated by the ceiling-mounted Pyroelectric Infrared (PIR) sensors. The similarity between normal training samples are measured based on Kullback-Leibler (KL) divergence of each pair of them. The natural clustering of normal activities is discovered through a self-tuning spectral clustering algorithm with unsupervised model selection on the eigenvectors of a modified similarity matrix. Hidden Markov Models (HMMs) are employed to model each cluster of normal activities and form feature vectors. One-Class Support Vector Machines (OSVMs) are used to profile the normal activities and detect abnormal activities. To validate the efficacy of our method, we conducted experiments in real indoor environments. The encouraging results show that our method is able to detect abnormal activities given only the normal training samples, which aims to avoid the laborious and inconsistent data labeling process. PMID:27271632

  13. Abnormal Activity Detection Using Pyroelectric Infrared Sensors.

    PubMed

    Luo, Xiaomu; Tan, Huoyuan; Guan, Qiuju; Liu, Tong; Zhuo, Hankz Hankui; Shen, Baihua

    2016-01-01

    Healthy aging is one of the most important social issues. In this paper, we propose a method for abnormal activity detection without any manual labeling of the training samples. By leveraging the Field of View (FOV) modulation, the spatio-temporal characteristic of human activity is encoded into low-dimension data stream generated by the ceiling-mounted Pyroelectric Infrared (PIR) sensors. The similarity between normal training samples are measured based on Kullback-Leibler (KL) divergence of each pair of them. The natural clustering of normal activities is discovered through a self-tuning spectral clustering algorithm with unsupervised model selection on the eigenvectors of a modified similarity matrix. Hidden Markov Models (HMMs) are employed to model each cluster of normal activities and form feature vectors. One-Class Support Vector Machines (OSVMs) are used to profile the normal activities and detect abnormal activities. To validate the efficacy of our method, we conducted experiments in real indoor environments. The encouraging results show that our method is able to detect abnormal activities given only the normal training samples, which aims to avoid the laborious and inconsistent data labeling process. PMID:27271632

  14. Low-coherence interferometric sensor system utilizing an integrated optics configuration

    NASA Astrophysics Data System (ADS)

    Plissi, M. V.; Rogers, A. J.; Brassington, D. J.; Wilson, M. G. F.

    1995-08-01

    The implementation of a twin Mach-Zehnder reference interferometer in an integrated optics substrate is described. From measurements of the fringe visibilities, an identification of the fringe order is attempted as a way to provide an absolute sensor for any parameter capable of modifying the difference in path length between two interfering optical paths.

  15. SPR based fiber-optic sensor with enhanced electric field intensity and figure of merit using different single and bimetallic configurations

    NASA Astrophysics Data System (ADS)

    Tabassum, Rana; Gupta, Banshi D.

    2016-05-01

    We present numerical simulations of electric field intensity, sensitivity and figure of merit (FOM) for different single and bimetallic configured surface plasmon resonance (SPR) fiber optic sensors. The metals considered are gold (Au), silver (Ag), copper (Cu) and aluminum (Al). The overall performance of the sensor is evaluated in terms of electric field intensity, sensitivity, FOM, chemical stability and the cost of fabrication of the sensor. More specifically, in terms of the sensing parameters, Al and Cu bimetallic configuration is found to be much better than the single and the other bimetallic configured sensors. The bimetallic configuration of Al and Cu for fiber optic SPR sensor is also evaluated experimentally. Additionally, the film adhesion capability of both the materials gets improved when used in bimetallic combination which further improves the chemical stability of the sensor; this is a serious problem with Al and Cu in their single layer configuration. The combinations which possess gold as outer layer are more chemically stable but found to be weaker in terms of sensing parameters and cost of fabrication as gold is highly expensive.

  16. An active sensor for monitoring bearing wear by means of an eddy current displacement sensor

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Toshihiko; Ueda, Masahiro

    2007-01-01

    A new and simple sensor for directly monitoring bearing wear has been developed by improving an eddy current displacement sensor. The sensor can be applied for non-metal shafts as well as metal shafts, and in this sense, we call it an 'active sensor'. In this sensor, an aluminium foil, used as a target metal for the eddy current sensor, has been sandwiched between two wedge-shaped acrylic plates and combined with an eddy current displacement sensor as a unit. The whole system consists of this new sensor, a data processing system including an amplifier, a 14-bit A/D converter, a personal computer and a display. The error of this system was about 20 µm, which was sufficiently small for use in a practical plant.

  17. Characterization of Mo/Au Transition-Edge Sensors with Different Geometric Configurations

    NASA Astrophysics Data System (ADS)

    Smith, S. J.; Adams, J. S.; Bandler, S. R.; Busch, S. E.; Chervenak, J. A.; Eckart, M. E.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Lee, S. J.; Porst, J.-P.; Porter, F. S.; Sadleir, J. E.

    2014-08-01

    Mo/Au transition-edge sensors exhibit weak-link behavior in the measured temperature, and field, dependence of the critical current . This is a consequence of the longitudinal proximitization between the Nb electrical bias contacts and the bilayer. Understanding how weak-link superconductivity impacts the resistive transition and the detector energy resolution is of great interest. In this contribution we present studies of for three devices that have different geometries of metallic depositions on top of the sensor used for noise mitigation and X-ray absorption. Results show that these features change the measured compared to the previously seen measurements on devices without additional deposition layers. Measurements of the small signal transition parameters and also reveal differences between designs that impact the measured response to X-rays and energy resolution.

  18. Virtual Wireless Sensor Networks: Adaptive Brain-Inspired Configuration for Internet of Things Applications.

    PubMed

    Toyonaga, Shinya; Kominami, Daichi; Murata, Masayuki

    2016-01-01

    Many researchers are devoting attention to the so-called "Internet of Things" (IoT), and wireless sensor networks (WSNs) are regarded as a critical technology for realizing the communication infrastructure of the future, including the IoT. Against this background, virtualization is a crucial technique for the integration of multiple WSNs. Designing virtualized WSNs for actual environments will require further detailed studies. Within the IoT environment, physical networks can undergo dynamic change, and so, many problems exist that could prevent applications from running without interruption when using the existing approaches. In this paper, we show an overall architecture that is suitable for constructing and running virtual wireless sensor network (VWSN) services within a VWSN topology. Our approach provides users with a reliable VWSN network by assigning redundant resources according to each user's demand and providing a recovery method to incorporate environmental changes. We tested this approach by simulation experiment, with the results showing that the VWSN network is reliable in many cases, although physical deployment of sensor nodes and the modular structure of the VWSN will be quite important to the stability of services within the VWSN topology. PMID:27548177

  19. Experimental characterization of Polaroid ultrasonic sensors in single and phased array configuration

    NASA Astrophysics Data System (ADS)

    Cao, Alex; Borenstein, Johann

    2002-07-01

    Many mobile robots use Polaroid ultrasonic sensors for obstacle avoidance. This paper describes the experimental characterization of these sensors using a unique, fully automated testbed system. Using this testbed, we gathered large data sets of 5,000-16,000 data points in every experiment for characterization purposes; in a repeatable fashion and without human supervision. In the experimental characterization reported in this paper we focused on a comparison of the beamwidth of a single sonar with that of a dual sonar phased array. For the single sonar we found that flat walls trigger echo signals up to an angle of +/- 42 degree(s), which is well beyond the traditional assumed beamwidth of +/- 15 degree(s). We determined that these echoes result from the secondary and tertiary lobe of the well known multi-lobed propagation patterns of Polaroid ultrasonic sensors. In contrast, with the dual sonar phased array echo signals were triggered only up to beamwidths of 4-6 degree(s). The results in this paper were obtained for two test targets: a specular surface and a cylindrical object.

  20. Twin Knudsen Cell Configuration for Activity Measurements by Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.

    1996-01-01

    A twin Knudsen cell apparatus for alloy activity measurements by mass spectrometry is described. Two Knudsen cells - one containing an alloy and one containing a pure component - are mounted on a single flange and translated into the sampling region via a motorized x-y table. Mixing of the molecular beams from the cells is minimized by a novel system of shutters. Activity measurements were taken on two well-characterized alloys to verify the operation of the system. Silver activity measurements are reported for Ag-Cu alloys and aluminum activity measurements are reported for Fe-Al alloys. The temperature dependence of activity for a 0.474 mol fraction Al-Fe alloy gives a partial molar heat of aluminum. Measurements taken with the twin cell show good agreement with literature values for these alloys.

  1. Performance of fluorescence retrieval methods and fluorescence spectrum reconstruction under various sensor spectral configurations

    NASA Astrophysics Data System (ADS)

    Li, Rong; Zhao, Feng

    2015-10-01

    Solar-induced chlorophyll fluorescence is closely related to photosynthesis and can serve as an indicator of plant status. Several methods have been proposed to retrieve fluorescence signal (Fs) either at specific spectral bands or within the whole fluorescence emission region. In this study, we investigated the precision of the fluorescence signal obtained through these methods under various sensor spectral characteristics. Simulated datasets generated by the SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes) model with known `true' Fs as well as an experimental dataset are exploited to investigate four commonly used Fs retrieval methods, namely the original Fraunhofer Line Discriminator method (FLD), the 3 bands FLD (3FLD), the improved FLD (iFLD), and the Spectral Fitting Methods (SFMs). Fluorescence Spectrum Reconstruction (FSR) method is also investigated using simulated datasets. The sensor characteristics of spectral resolution (SR) and signal-to-noise ratio (SNR) are taken into account. According to the results, finer SR and SNR both lead to better accuracy. Lowest precision is obtained for the FLD method with strong overestimation. Some improvements are made by the 3FLD method, but it still tends to overestimate. Generally, the iFLD method and the SFMs provide better accuracy. As to FSR, the shape and magnitude of reconstructed Fs are generally consistent with the `true' Fs distributions when fine SR is exploited. With coarser SR, however, though R2 of the retrieved Fs may be high, large bias is likely to be obtained as well.

  2. Torsional mode ultrasonic helical waveguide sensor for re-configurable temperature measurement

    NASA Astrophysics Data System (ADS)

    Periyannan, Suresh; Rajagopal, Prabhu; Balasubramaniam, Krishnan

    2016-06-01

    This paper introduces an ultrasonic torsional mode based technique, configured in the form of a helical "spring-like" waveguide, for multi-level temperature measurement. The multiple sensing levels can be repositioned by stretching or collapsing the spring to provide simultaneous measurements at different desired spacing in a given area/volume. The transduction is performed using piezo-electric crystals that generate and receive T(0,1) mode in a pulse echo mode. The gage lengths and positions of measurements are based on machining multiple reflector notches in the waveguide at required positions. The time of fight (TOF) measurements between the reflected signals from the notches provide local temperatures that compare well with co-located thermocouples.

  3. CMOS Active-Pixel Image Sensor With Simple Floating Gates

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R.; Nakamura, Junichi; Kemeny, Sabrina E.

    1996-01-01

    Experimental complementary metal-oxide/semiconductor (CMOS) active-pixel image sensor integrated circuit features simple floating-gate structure, with metal-oxide/semiconductor field-effect transistor (MOSFET) as active circuit element in each pixel. Provides flexibility of readout modes, no kTC noise, and relatively simple structure suitable for high-density arrays. Features desirable for "smart sensor" applications.

  4. Active cells for redundant and configurable articulated structures

    NASA Astrophysics Data System (ADS)

    Swensen, John P.; Nawroj, Ahsan I.; Pounds, Paul E. I.; Dollar, Aaron M.

    2014-10-01

    The proposed research effort explores the development of active cells—simple contractile electro-mechanical units that can be used as the material basis for larger articulable structures. Each cell, which might be considered a ‘muscle unit,’ consists of a contractile Nitinol Shape Memory Alloy (SMA) core with conductive terminals. Large numbers of these cells might be combined and externally powered to change phase, contracting to either articulate with a large strain or increase the stiffness of the ensemble, depending on the cell design. Unlike traditional work in modular robotics, the approach presented here focuses on cells that have a simplistic design and function, are inexpensive to fabricate, and are eventually scalable to sub-millimeter sizes, working toward our vision of articulated and robotic structures that can be custom-fabricated from large numbers of general cell units, similar to biological structures. In this paper, we present the design of the active cells and demonstrate their usage with three articulated structures built with them.

  5. Energy-aware Activity Classification using Wearable Sensor Networks.

    PubMed

    Dong, Bo; Montoye, Alexander; Moore, Rebecca; Pfeiffer, Karin; Biswas, Subir

    2013-05-29

    This paper presents implementation details, system characterization, and the performance of a wearable sensor network that was designed for human activity analysis. Specific machine learning mechanisms are implemented for recognizing a target set of activities with both out-of-body and on-body processing arrangements. Impacts of energy consumption by the on-body sensors are analyzed in terms of activity detection accuracy for out-of-body processing. Impacts of limited processing abilities for the on-body scenario are also characterized in terms of detection accuracy, by varying the background processing load in the sensor units. Impacts of varying number of sensors in terms of activity classification accuracy are also evaluated. Through a rigorous systems study, it is shown that an efficient human activity analytics system can be designed and operated even under energy and processing constraints of tiny on-body wearable sensors. PMID:25075266

  6. Impact of activated sludge process configuration on removal of micropollutants and estrogenicity.

    PubMed

    Ogunlaja, O O; Parker, W J

    2015-01-01

    The efficacy of three different wastewater treatment configurations, conventional activated sludge (CAS), nitrifying activated sludge (NAS) and biological nutrient removal (BNR) for removal of selected micropollutants from authentic wastewater was investigated. The processes were also characterized based on their proficiency to reduce the estrogenic activity of the influent wastewater using the in vitro recombinant yeast assay. The removal efficiency of trimethoprim improved with the complexity of the three treatment process configurations. Ibuprofen, androstendione, sulfamethoxazole, nonyl-phenol, estrone and bisphenol-A had moderate to high removals (>65%) while carbamazepine and meprobamate remained recalcitrant in the three treatment process configurations. The removal of gemfibrozil was better in the NAS than in BNR and CAS treatment configurations. The yeast estrogen screen (YES) assay analyses showed an improvement in estrogenicity removal in the BNR and NAS treatment configurations as compared to the CAS treatment configuration. Comparing the estrogenic responses from the three treatment configurations, the removal efficiencies followed the order of BNR=NAS>CAS and all were greater than 81%. PMID:26177411

  7. Force sensor for chameleon and Casimir force experiments with parallel-plate configuration

    NASA Astrophysics Data System (ADS)

    Almasi, Attaallah; Brax, Philippe; Iannuzzi, Davide; Sedmik, René I. P.

    2015-05-01

    The search for non-Newtonian forces has been pursued following many different paths. Recently it was suggested that hypothetical chameleon interactions, which might explain the mechanisms behind dark energy, could be detected in a high-precision force measurement. In such an experiment, interactions between parallel plates kept at constant separation could be measured as a function of the pressure of an ambient gas, thereby identifying chameleon interactions by their unique inverse dependence on the local mass density. During the past years we have been developing a new kind of setup complying with the stringent requirements of the proposed experiment. In this article we present the first and most important part of this setup—the force sensor. We discuss its design, fabrication, and characterization. From the results of the latter, we derive limits on chameleon interaction parameters that could be set by the forthcoming experiment. Finally, we describe the opportunity to use the same setup to measure Casimir forces at large surface separations with unprecedented accuracy, thereby potentially giving unambiguous answers to long-standing open questions.

  8. Experiments on active isolation using distributed PVDF error sensors

    NASA Technical Reports Server (NTRS)

    Lefebvre, S.; Guigou, C.; Fuller, C. R.

    1992-01-01

    A control system based on a two-channel narrow-band LMS algorithm is used to isolate periodic vibration at low frequencies on a structure composed of a rigid top plate mounted on a flexible receiving plate. The control performance of distributed PVDF error sensors and accelerometer point sensors is compared. For both sensors, high levels of global reduction, up to 32 dB, have been obtained. It is found that, by driving the PVDF strip output voltage to zero, the controller may force the structure to vibrate so that the integration of the strain under the length of the PVDF strip is zero. This ability of the PVDF sensors to act as spatial filters is especially relevant in active control of sound radiation. It is concluded that the PVDF sensors are flexible, nonfragile, and inexpensive and can be used as strain sensors for active control applications of vibration isolation and sound radiation.

  9. Opportunities for measuring wheelchair kinematics in match settings; reliability of a three inertial sensor configuration.

    PubMed

    van der Slikke, R M A; Berger, M A M; Bregman, D J J; Lagerberg, A H; Veeger, H E J

    2015-09-18

    Knowledge of wheelchair kinematics during a match is prerequisite for performance improvement in wheelchair basketball. Unfortunately, no measurement system providing key kinematic outcomes proved to be reliable in competition. In this study, the reliability of estimated wheelchair kinematics based on a three inertial measurement unit (IMU) configuration was assessed in wheelchair basketball match-like conditions. Twenty participants performed a series of tests reflecting different motion aspects of wheelchair basketball. During the tests wheelchair kinematics were simultaneously measured using IMUs on wheels and frame, and a 24-camera optical motion analysis system serving as gold standard. Results showed only small deviations of the IMU method compared to the gold standard, once a newly developed skid correction algorithm was applied. Calculated Root Mean Square Errors (RMSE) showed good estimates for frame displacement (RMSE≤0.05 m) and speed (RMSE≤0.1m/s), except for three truly vigorous tests. Estimates of frame rotation in the horizontal plane (RMSE<3°) and rotational speed (RMSE<7°/s) were very accurate. Differences in calculated Instantaneous Rotation Centres (IRC) were small, but somewhat larger in tests performed at high speed (RMSE up to 0.19 m). Average test outcomes for linear speed (ICCs>0.90), rotational speed (ICC>0.99) and IRC (ICC> 0.90) showed high correlations between IMU data and gold standard. IMU based estimation of wheelchair kinematics provided reliable results, except for brief moments of wheel skidding in truly vigorous tests. The IMU method is believed to enable prospective research in wheelchair basketball match conditions and contribute to individual support of athletes in everyday sports practice. PMID:26141162

  10. Video Guidance Sensors Using Remotely Activated Targets

    NASA Technical Reports Server (NTRS)

    Bryan, Thomas C.; Howard, Richard T.; Book, Michael L.

    2004-01-01

    Four updated video guidance sensor (VGS) systems have been proposed. As described in a previous NASA Tech Briefs article, a VGS system is an optoelectronic system that provides guidance for automated docking of two vehicles. The VGS provides relative position and attitude (6-DOF) information between the VGS and its target. In the original intended application, the two vehicles would be spacecraft, but the basic principles of design and operation of the system are applicable to aircraft, robots, objects maneuvered by cranes, or other objects that may be required to be aligned and brought together automatically or under remote control. In the first two of the four VGS systems as now proposed, the tracked vehicle would include active targets that would light up on command from the tracking vehicle, and a video camera on the tracking vehicle would be synchronized with, and would acquire images of, the active targets. The video camera would also acquire background images during the periods between target illuminations. The images would be digitized and the background images would be subtracted from the illuminated-target images. Then the position and orientation of the tracked vehicle relative to the tracking vehicle would be computed from the known geometric relationships among the positions of the targets in the image, the positions of the targets relative to each other and to the rest of the tracked vehicle, and the position and orientation of the video camera relative to the rest of the tracking vehicle. The major difference between the first two proposed systems and prior active-target VGS systems lies in the techniques for synchronizing the flashing of the active targets with the digitization and processing of image data. In the prior active-target VGS systems, synchronization was effected, variously, by use of either a wire connection or the Global Positioning System (GPS). In three of the proposed VGS systems, the synchronizing signal would be generated on, and

  11. Thin Film on CMOS Active Pixel Sensor for Space Applications

    PubMed Central

    Schulze Spuentrup, Jan Dirk; Burghartz, Joachim N.; Graf, Heinz-Gerd; Harendt, Christine; Hutter, Franz; Nicke, Markus; Schmidt, Uwe; Schubert, Markus; Sterzel, Juergen

    2008-01-01

    A 664 × 664 element Active Pixel image Sensor (APS) with integrated analog signal processing, full frame synchronous shutter and random access for applications in star sensors is presented and discussed. A thick vertical diode array in Thin Film on CMOS (TFC) technology is explored to achieve radiation hardness and maximum fill factor.

  12. Active-Pixel Image Sensors With Programmable Resolution

    NASA Technical Reports Server (NTRS)

    Kemeny, Sabrina E.; Fossum, Eric R.; Pain, Bedabrata; Nakamura, Junichi; Matthies, Larry H.

    1996-01-01

    Active-pixel image sensors with programmable resolution proposed for use in applications in which speed and efficiency of processing of image data enhanced by providing those data at varying resolutions. Such applications include modeling of biological vision, stereoscopic range-finding, recognition of patterns, tracking targets, and progressive transmission of compressed images. In target-tracking application, sensor initially forms low-resolution image from which area of interest identified, then sensor set at high resolution for examination of identified area. Outputs of contiguous pixels combined. Sensor of this type made to act as though it comprised fewer and larger pixels.

  13. Active Self-Testing Noise Measurement Sensors for Large-Scale Environmental Sensor Networks

    PubMed Central

    Domínguez, Federico; Cuong, Nguyen The; Reinoso, Felipe; Touhafi, Abdellah; Steenhaut, Kris

    2013-01-01

    Large-scale noise pollution sensor networks consist of hundreds of spatially distributed microphones that measure environmental noise. These networks provide historical and real-time environmental data to citizens and decision makers and are therefore a key technology to steer environmental policy. However, the high cost of certified environmental microphone sensors render large-scale environmental networks prohibitively expensive. Several environmental network projects have started using off-the-shelf low-cost microphone sensors to reduce their costs, but these sensors have higher failure rates and produce lower quality data. To offset this disadvantage, we developed a low-cost noise sensor that actively checks its condition and indirectly the integrity of the data it produces. The main design concept is to embed a 13 mm speaker in the noise sensor casing and, by regularly scheduling a frequency sweep, estimate the evolution of the microphone's frequency response over time. This paper presents our noise sensor's hardware and software design together with the results of a test deployment in a large-scale environmental network in Belgium. Our middle-range-value sensor (around €50) effectively detected all experienced malfunctions, in laboratory tests and outdoor deployments, with a few false positives. Future improvements could further lower the cost of our sensor below €10. PMID:24351634

  14. Antiausterity activity of arctigenin enantiomers: importance of (2R,3R)-absolute configuration.

    PubMed

    Awale, Suresh; Kato, Mamoru; Dibwe, Dya Fita; Li, Feng; Miyoshi, Chika; Esumi, Hiroyasu; Kadota, Shigetoshi; Tezuka, Yasuhiro

    2014-01-01

    From a MeOH extract of powdered roots of Wikstroemia indica, six dibenzyl-gamma-butyrolactone-type lignans with (2S,3S)-absolute configuration [(+)-arctigenin (1), (+)-matairesinol (2), (+)-trachelogenin (3), (+)-nortrachelogenin (4), (+)-hinokinin (5), and (+)-kusunokinin (6)] were isolated, whereas three dibenzyl-gamma-butyrolactone-type lignans with (2R,3R)-absolute configuration [(-)-arctigenin (1*), (-)-matairesinol (2*), (-)-trachelogenin (3*)] were isolated from Trachelospermum asiaticum. The in vitro preferential cytotoxic activity of the nine compounds was evaluated against human pancreatic PANC-1 cancer cells in nutrient-deprived medium (NDM), but none of the six lignans (1-6) with (2S,3S)-absolute configuration showed preferential cytotoxicity. On the other hand, three lignans (1*-3*) with (2R,3R)-absolute configuration exhibited preferential cytotoxicity in a concentration-dependent manner with PC50 values of 0.54, 6.82, and 5.85 microM, respectively. Furthermore, the effect of (-)- and (+)-arctigenin was evaluated against the activation of Akt, which is a key process in the tolerance to nutrition starvation. Interestingly, only (-)-arctigenin (1*) strongly suppressed the activation of Akt. These results indicate that the (2R,3R)-absolute configuration of (-)-enantiomers should be required for the preferential cytotoxicity through the inhibition of Akt activation. PMID:24660468

  15. Integrated active sensor system for real time vibration monitoring

    NASA Astrophysics Data System (ADS)

    Liang, Qijie; Yan, Xiaoqin; Liao, Xinqin; Cao, Shiyao; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-11-01

    We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0-60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems.

  16. Integrated active sensor system for real time vibration monitoring

    PubMed Central

    Liang, Qijie; Yan, Xiaoqin; Liao, Xinqin; Cao, Shiyao; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-01-01

    We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0–60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems. PMID:26538293

  17. Integrated active sensor system for real time vibration monitoring.

    PubMed

    Liang, Qijie; Yan, Xiaoqin; Liao, Xinqin; Cao, Shiyao; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-01-01

    We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0-60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems. PMID:26538293

  18. Effects of planting configuration and in-row plant spacing on photosynthetic active radiation interception for three irrigated potato cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research studies have evaluated the production of potatoes (Solanum tuberosum L.) grown in conventional and bed planting configurations. However, intercepted photosynthetically active radiation (PAR) from these planting configurations has not been quantified. A study conducted in 2008 and 2009 quant...

  19. CMOS Active Pixel Sensor Technology and Reliability Characterization Methodology

    NASA Technical Reports Server (NTRS)

    Chen, Yuan; Guertin, Steven M.; Pain, Bedabrata; Kayaii, Sammy

    2006-01-01

    This paper describes the technology, design features and reliability characterization methodology of a CMOS Active Pixel Sensor. Both overall chip reliability and pixel reliability are projected for the imagers.

  20. The Sandia MEMS passive shock sensor : FY07 maturation activities.

    SciTech Connect

    Houston, Jack E.; Blecke, Jill; Mitchell, John Anthony; Wittwer, Jonathan W.; Crowson, Douglas A.; Clemens, Rebecca C.; Walraven, Jeremy Allen; Epp, David S.; Baker, Michael Sean

    2008-08-01

    This report describes activities conducted in FY07 to mature the MEMS passive shock sensor. The first chapter of the report provides motivation and background on activities that are described in detail in later chapters. The second chapter discusses concepts that are important for integrating the MEMS passive shock sensor into a system. Following these two introductory chapters, the report details modeling and design efforts, packaging, failure analysis and testing and validation. At the end of FY07, the MEMS passive shock sensor was at TRL 4.

  1. CMOS Active Pixel Sensor Star Tracker with Regional Electronic Shutter

    NASA Technical Reports Server (NTRS)

    Yadid-Pecht, Orly; Pain, Bedabrata; Staller, Craig; Clark, Christopher; Fossum, Eric

    1996-01-01

    The guidance system in a spacecraft determines spacecraft attitude by matching an observed star field to a star catalog....An APS(active pixel sensor)-based system can reduce mass and power consumption and radiation effects compared to a CCD(charge-coupled device)-based system...This paper reports an APS (active pixel sensor) with locally variable times, achieved through individual pixel reset (IPR).

  2. Engineering the Morphology and Configuration of Ternary Heterostructures for Improving Their Photocatalytic Activity.

    PubMed

    Li, Kui; Chen, Rong; Li, Shun-Li; Xie, Shuai-Lei; Cao, Xue-Li; Dong, Long-Zhang; Bao, Jian-Chun; Lan, Ya-Qian

    2016-02-01

    Heteronanomaterials composed of suitable semiconductors enable the direct conversion from solar power into clean and renewable energy. Ternary heterostructures with appropriate configuration and morphology possess rich and varied properties, especially for improving the photocatalytic activity and stability synchronously. However, suitable ternary heterostructure prototypes and facile while effective strategy for modulating their morphology and configuration are still scarce. Herein, various ternary ZnS-CdS-Zn(1-x)Cd(x)S heterostructures with tunable morphology (0 to 2 D) and semiconductor configurations (randomly distributed, interface mediated, and quantum dots sensitized core@shell heterostructures) were facilely synthesized via one-pot hydrothermal method resulting from the different molecular structures of the amine solvents. Semiconductor morphology, especially configuration of the ternary heterostructure, shows dramatic effect on their photocatalytic activity. The CdS sensitized porous Zn(1-x)CdxS@ZnS core@shell takes full advantage of ZnS, Zn(1-x)Cd(x)S and CdS and shows the maximal photocatalytic H2-production rate of 100.2 mmol/h/g and excellent stability over 30 h. This study provides some guidelines for the design and synthesis of high-performance ternary heterostructure via modulation of semiconductor configuration and morphology using one-pot method. PMID:26835705

  3. Active vibration reduction by optimally placed sensors and actuators with application to stiffened plates by beams

    NASA Astrophysics Data System (ADS)

    Daraji, A. H.; Hale, J. M.

    2014-10-01

    This study concerns new investigation of active vibration reduction of a stiffened plate bonded with discrete sensor/actuator pairs located optimally using genetic algorithms based on a developed finite element modeling. An isotropic plate element stiffened by a number of beam elements on its edges and having a piezoelectric sensor and actuator pair bonded to its surfaces is modeled using the finite element method and Hamilton’s principle, taking into account the effects of piezoelectric mass, stiffness and electromechanical coupling. The modeling is based on the first order shear deformation theory taking into account the effects of bending, membrane and shear deformation for the plate, the stiffening beam and the piezoelectric patches. A Matlab finite element program has been built for the stiffened plate model and verified with ANSYS and also experimentally. Optimal placement of ten piezoelectric sensor/actuator pairs and optimal feedback gain for active vibration reduction are investigated for a plate stiffened by two beams arranged in the form of a cross. The genetic algorithm was set up for optimization of sensor/actuator placement and feedback gain based on the minimization of the optimal linear quadratic index as an objective function to suppress the first six modes of vibration. Comparison study is presented for active vibration reduction of a square cantilever plate stiffened by crossed beams with two sensor/actuator configurations: firstly, ten piezoelectric sensor/actuator pairs are located in optimal positions; secondly, a piezoelectric layer of single sensor/actuator pair covering the whole of the stiffened plate as a SISO system.

  4. CMOS Monolithic Active Pixel Sensors (MAPS): Developments and future outlook

    NASA Astrophysics Data System (ADS)

    Turchetta, R.; Fant, A.; Gasiorek, P.; Esbrand, C.; Griffiths, J. A.; Metaxas, M. G.; Royle, G. J.; Speller, R.; Venanzi, C.; van der Stelt, P. F.; Verheij, H.; Li, G.; Theodoridis, S.; Georgiou, H.; Cavouras, D.; Hall, G.; Noy, M.; Jones, J.; Leaver, J.; Machin, D.; Greenwood, S.; Khaleeq, M.; Schulerud, H.; Østby, J. M.; Triantis, F.; Asimidis, A.; Bolanakis, D.; Manthos, N.; Longo, R.; Bergamaschi, A.

    2007-12-01

    Re-invented in the early 1990s, on both sides of the Atlantic, Monolithic Active Pixel Sensors (MAPS) in a CMOS technology are today the most sold solid-state imaging devices, overtaking the traditional technology of Charge-Coupled Devices (CCD). The slow uptake of CMOS MAPS started with low-end applications, for example web-cams, and is slowly pervading the high-end applications, for example in prosumer digital cameras. Higher specifications are required for scientific applications: very low noise, high speed, high dynamic range, large format and radiation hardness are some of these requirements. This paper will present a brief overview of the CMOS Image Sensor technology and of the requirements for scientific applications. As an example, a sensor for X-ray imaging will be presented. This sensor was developed within a European FP6 Consortium, intelligent imaging sensors (I-ImaS).

  5. Developing sensor activity relationships for the JPL electronic nose sensors using molecular modeling and QSAR techniques

    NASA Technical Reports Server (NTRS)

    Shevade, A. V.; Ryan, M. A.; Homer, M. L.; Jewell, A. D.; Zhou, H.; Manatt, K.; Kisor, A. K.

    2005-01-01

    We report a Quantitative Structure-Activity Relationships (QSAR) study using Genetic Function Approximations (GFA) to describe the polymer-carbon composite sensor activities in the JPL Electronic Nose, when exposed to chemical vapors at parts-per-million concentration levels.

  6. Calibrating a novel multi-sensor physical activity measurement system

    PubMed Central

    John, D; Liu, S; Sasaki, J E; Howe, C A; Staudenmayer, J; Gao, R X; Freedson, P S

    2011-01-01

    Advancing the field of physical activity (PA) monitoring requires the development of innovative multi-sensor measurement systems that are feasible in the free-living environment. The use of novel analytical techniques to combine and process these multiple sensor signals is equally important. This paper, describes a novel multi-sensor ‘Integrated PA Measurement System’ (IMS), the lab-based methodology used to calibrate the IMS, techniques used to predict multiple variables from the sensor signals, and proposes design changes to improve the feasibility of deploying the IMS in the free-living environment. The IMS consists of hip and wrist acceleration sensors, two piezoelectric respiration sensors on the torso, and an ultraviolet radiation sensor to obtain contextual information (indoors vs. outdoors) of PA. During lab-based calibration of the IMS, data were collected on participants performing a PA routine consisting of seven different ambulatory and free-living activities while wearing a portable metabolic unit (criterion measure) and the IMS. Data analyses on the first 50 adult participants are presented. These analyses were used to determine if the IMS can be used to predict the variables of interest. Finally, physical modifications for the IMS that could enhance feasibility of free-living use are proposed and refinement of the prediction techniques is discussed. PMID:21813941

  7. Characterization of a Depleted Monolithic Active Pixel Sensor (DMAPS) prototype

    NASA Astrophysics Data System (ADS)

    Obermann, T.; Havranek, M.; Hemperek, T.; Hügging, F.; Kishishita, T.; Krüger, H.; Marinas, C.; Wermes, N.

    2015-03-01

    New monolithic pixel detectors integrating CMOS electronics and sensor on the same silicon substrate are currently explored for particle tracking in future HEP experiments, most notably at the LHC . The innovative concept of Depleted Monolithic Active Pixel Sensors (DMAPS) is based on high resistive silicon bulk material enabling full substrate depletion and the application of an electrical drift field for fast charge collection, while retaining full CMOS capability for the electronics. The technology (150 nm) used offers quadruple wells and allows to implement the pixel electronics with independently isolated N- and PMOS transistors. Results of initial studies on the charge collection and sensor performance are presented.

  8. Corrosion damage detection with piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Thomas, Dustin T.; Welter, John T.; Giurgiutiu, Victor

    2004-07-01

    Since today's aging fleet is intended to far exceed their proposed design life, monitoring the structural integrity of those aircraft has become a priority issue for today's Air Force. One of the most critical structural problems is corrosion. In fact the KC-135 now costs $1.2 billion a year to repair corrosion. In this paper, we plan to show the use of Lamb waves to detect material loss in thin plates representative of aircraft skins. To do this we will use embedded transducers called Piezoelectric Wafer Active Sensor (PWAS) in a pitch-catch configuration. The sensors were placed on a grid pattern. Material loss through corrosion was simulated by removing the material mechanically with an abrasive tool. Thus, simulated corrosion pits of various depths and area coverage were made. Three-count tone burst wave packets were used. The Lamb wave packets were sent in a pitch-catch mode from one transmitter PWAS to the other PWAS in the grid acting as receivers. The Lamb wave mode used in these experiments was A1, since this was found to be more sensitive to changes due to material loss. At the frequencies considered in our experiments, the A1 waves are highly dispersive. It was found that, as the Lamb wave travels through simulated corrosion damage, the signal changes. The observed changes were in the signal wavelength (due to change in the dispersive properties of the medium) and in signal amplitude (due to redistribution of energy in the wave packet). This change in signal can be correlated to the magnitude of damage. To achieve this, we have used several approaches: (a) direct correlation between the sent and the received signals; (b) wavelet transform of the signal followed by correlation of the wavelet coefficients time-frequency maps; (c) Hilbert transform of the signal to produce the signal envelope and comparison of the resulting envelope signals (d) neural network correlation between the sent and received signals. It was found that these methods work well

  9. Effect of membrane bioreactor configurations on sludge structure and microbial activity.

    PubMed

    Clouzot, L; Roche, N; Marrot, B

    2011-01-01

    The aim of this paper was to determine the effect of two different membrane bioreactor (MBR) configurations (external/immersed) on sludge structure and microbial activity. Sludge structure was deduced from rheological measurements. The high shear stress induced by the recirculation pump in the external MBR was shown to result in decreasing viscosity due to activated sludge (AS) deflocculation. Besides, soluble microbial products (SMP) release was higher in the external MBR (5 mgCOD gMLVSS(-1)) than in the immersed configuration (2 mgCOD gMLVSS(-1)). Microbial activity was followed from respirometry tests by focusing on the distinction between heterotrophs and autotrophs. An easier autotrophic microbe development was then observed in the immersed MBR compared to the external one. However, the external MBR was shown to allow better heterotrophic microbe development. PMID:20947340

  10. MAPLE activities and applications in gas sensors

    NASA Astrophysics Data System (ADS)

    Jelínek, Miroslav; Remsa, Jan; Kocourek, Tomáš; Kubešová, Barbara; Schůrek, Jakub; Myslík, Vladimír

    2011-11-01

    During the last decade, many groups have grown thin films of various organic materials by the cryogenic Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique with a wide range of applications. This contribution is focused on the summary of our results with deposition and characterization of thin films of fibrinogen, pullulan derivates, azo-polyurethane, cryoglobulin, polyvinyl alcohol, and bovine serum albumin dissolved in physiological serum, dimethyl sulfoxide, sanguine plasma, phosphate buffer solution, H2O, ethylene glycol, and tert-butanol. MAPLE films were characterized using FTIR, AFM, Raman scattering, and SEM. For deposition, a special hardware was developed including a unique liquid nitrogen cooled target holder. Overview of MAPLE thin film applications is given. We studied SnAcAc, InAcAc, SnO2, porphyrins, and polypyrrole MAPLE fabricated films as small resistive gas sensors. Sensors were tested with ozone, nitrogen dioxide, hydrogen, and water vapor gases. In the last years, our focus was on the study of fibrinogen-based scaffolds for application in tissue engineering, wound healing, and also as a part of layers for medical devices.

  11. Laser speckle strain and deformation sensor using linear array image cross-correlation method for specifically arranged triple-beam triple-camera configuration

    NASA Technical Reports Server (NTRS)

    Sarrafzadeh-Khoee, Adel K. (Inventor)

    2000-01-01

    The invention provides a method of triple-beam and triple-sensor in a laser speckle strain/deformation measurement system. The triple-beam/triple-camera configuration combined with sequential timing of laser beam shutters is capable of providing indications of surface strain and structure deformations. The strain and deformation quantities, the four variables of surface strain, in-plane displacement, out-of-plane displacement and tilt, are determined in closed form solutions.

  12. COCHLEAR IMPLANT ELECTRODE CONFIGURATION EFFECTS ON ACTIVATION THRESHOLD AND TONOTOPIC SELECTIVITY

    PubMed Central

    Snyder, Russell L.; Middlebrooks, John C.; Bonham, Ben H.

    2008-01-01

    The multichannel design of contemporary cochlear implants (CIs) is predicated on the assumption that each channel activates a relatively restricted and independent sector of the deaf auditory nerve array, just as a sound within a restricted frequency band activates a restricted region of the normal cochlea The independence of CI channels, however, is limited; and the factors that determine their independence, the relative overlap of the activity patterns that they evoke, are poorly understood. In this study, we evaluate the spread of activity evoked by cochlear implant channels by monitoring activity at 16 sites along the tonotopic axis of the guinea pig inferior colliculus (IC). “Spatial tuning curves” (STCs) measured in this way serve as an estimate of activation spread within the cochlea and the ascending auditory pathways. We contrast natural stimulation using acoustic tones with two kinds of electrical stimulation either (1) a loose fitting banded array consisting of a cylindrical silicone elastomer carrier with a linear series of ring contacts; or (2) a space-filling array consisting of a tapered silicone elastomer carrier that is designed to fit snugly into the guinea pig scala tympani with a linear series of ball contacts positioned along it Spatial tuning curves evoked by individual acoustic tones, and by activation of each contact of each array as a monopole, bipole or tripole were recorded. Several channel configurations and a wide range of electrode separations were tested for each array, and their thresholds and selectivity were estimated. The results indicate that the tapered space-filling arrays evoked more restricted activity patterns at lower thresholds than did the banded arrays. Monopolar stimulation (one intracochlear contact activated with an extracochlear return) using either array evoked broad activation patterns that involved the entire recording array at current levels < 6dB SL, but at relatively low thresholds. Bi- and tripolar

  13. Cochlear implant electrode configuration effects on activation threshold and tonotopic selectivity.

    PubMed

    Snyder, Russell L; Middlebrooks, John C; Bonham, Ben H

    2008-01-01

    The multichannel design of contemporary cochlear implants (CIs) is predicated on the assumption that each channel activates a relatively restricted and independent sector of the deaf auditory nerve array, just as a sound within a restricted frequency band activates a restricted region of the normal cochlea The independence of CI channels, however, is limited; and the factors that determine their independence, the relative overlap of the activity patterns that they evoke, are poorly understood. In this study, we evaluate the spread of activity evoked by cochlear implant channels by monitoring activity at 16 sites along the tonotopic axis of the guinea pig inferior colliculus (IC). "Spatial tuning curves" (STCs) measured in this way serve as an estimate of activation spread within the cochlea and the ascending auditory pathways. We contrast natural stimulation using acoustic tones with two kinds of electrical stimulation either (1) a loose fitting banded array consisting of a cylindrical silicone elastomer carrier with a linear series of ring contacts; or (2) a space-filling array consisting of a tapered silicone elastomer carrier that is designed to fit snugly into the guinea pig scala tympani with a linear series of ball contacts positioned along it Spatial tuning curves evoked by individual acoustic tones, and by activation of each contact of each array as a monopole, bipole or tripole were recorded. Several channel configurations and a wide range of electrode separations were tested for each array, and their thresholds and selectivity were estimated. The results indicate that the tapered space-filling arrays evoked more restricted activity patterns at lower thresholds than did the banded arrays. Monopolar stimulation (one intracochlear contact activated with an extracochlear return) using either array evoked broad activation patterns that involved the entire recording array at current levels <6dBSL, but at relatively low thresholds. Bi- and tri

  14. Towards using a Monolithic Active Pixel Sensor for in vivo beam monitoring of Intensity Modulated Radiotherapy

    NASA Astrophysics Data System (ADS)

    Page, R. F.; Abbott, N. L.; Davies, J.; Dyke, E. L.; Randles, H. J.; Velthuis, J. J.; Fletcher, S.; Gregory, S. D.; Hall, C.; John, A.; Lawrence, H.; Stevens, P. H.; Hugtenburg, R. P.; Tunbridge, V.

    2013-12-01

    The use of Intensity Modulated Radiotherapy (IMRT) for cancer treatments is entering wider use. These treatments involve using a complex configuration of field modifying components, known as Multileaf Collimators (MLC), to dynamically shape the beam. A treatment consists of a sequence of irregular shaped fields, which means real time monitoring and verification is essential. In the current framework the treatment plans are verified before the patient is treated, but not during. The aim of our collaboration is to monitor the treatment being given to the patient. This is achieved by placing a camera system using an ultra-thin Monolithic Active Pixel Sensor (MAPS) upstream of the patient.

  15. Monolithic active pixel sensors (MAPS) in a VLSI CMOS technology

    NASA Astrophysics Data System (ADS)

    Turchetta, R.; French, M.; Manolopoulos, S.; Tyndel, M.; Allport, P.; Bates, R.; O'Shea, V.; Hall, G.; Raymond, M.

    2003-03-01

    Monolithic Active Pixel Sensors (MAPS) designed in a standard VLSI CMOS technology have recently been proposed as a compact pixel detector for the detection of high-energy charged particle in vertex/tracking applications. MAPS, also named CMOS sensors, are already extensively used in visible light applications. With respect to other competing imaging technologies, CMOS sensors have several potential advantages in terms of low cost, low power, lower noise at higher speed, random access of pixels which allows windowing of region of interest, ability to integrate several functions on the same chip. This brings altogether to the concept of 'camera-on-a-chip'. In this paper, we review the use of CMOS sensors for particle physics and we analyse their performances in term of the efficiency (fill factor), signal generation, noise, readout speed and sensor area. In most of high-energy physics applications, data reduction is needed in the sensor at an early stage of the data processing before transfer of the data to tape. Because of the large number of pixels, data reduction is needed on the sensor itself or just outside. This brings in stringent requirements on the temporal noise as well as to the sensor uniformity, expressed as a Fixed Pattern Noise (FPN). A pixel architecture with an additional transistor is proposed. This architecture, coupled to correlated double sampling of the signal will allow cancellation of the two dominant noise sources, namely the reset or kTC noise and the FPN. A prototype has been designed in a standard 0.25 μm CMOS technology. It has also a structure for electrical calibration of the sensor. The prototype is functional and detailed tests are under way.

  16. Active Sensing System with In Situ Adjustable Sensor Morphology

    PubMed Central

    Nurzaman, Surya G.; Culha, Utku; Brodbeck, Luzius; Wang, Liyu; Iida, Fumiya

    2013-01-01

    Background Despite the widespread use of sensors in engineering systems like robots and automation systems, the common paradigm is to have fixed sensor morphology tailored to fulfill a specific application. On the other hand, robotic systems are expected to operate in ever more uncertain environments. In order to cope with the challenge, it is worthy of note that biological systems show the importance of suitable sensor morphology and active sensing capability to handle different kinds of sensing tasks with particular requirements. Methodology This paper presents a robotics active sensing system which is able to adjust its sensor morphology in situ in order to sense different physical quantities with desirable sensing characteristics. The approach taken is to use thermoplastic adhesive material, i.e. Hot Melt Adhesive (HMA). It will be shown that the thermoplastic and thermoadhesive nature of HMA enables the system to repeatedly fabricate, attach and detach mechanical structures with a variety of shape and size to the robot end effector for sensing purposes. Via active sensing capability, the robotic system utilizes the structure to physically probe an unknown target object with suitable motion and transduce the arising physical stimuli into information usable by a camera as its only built-in sensor. Conclusions/Significance The efficacy of the proposed system is verified based on two results. Firstly, it is confirmed that suitable sensor morphology and active sensing capability enables the system to sense different physical quantities, i.e. softness and temperature, with desirable sensing characteristics. Secondly, given tasks of discriminating two visually indistinguishable objects with respect to softness and temperature, it is confirmed that the proposed robotic system is able to autonomously accomplish them. The way the results motivate new research directions which focus on in situ adjustment of sensor morphology will also be discussed. PMID:24416094

  17. Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration

    NASA Astrophysics Data System (ADS)

    Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

    2006-09-01

    A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of ˜60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of ˜170 mW at a wavelength of 1455 nm and a low EDFA pump power of ˜40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.

  18. Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration.

    PubMed

    Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

    2006-09-15

    A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge. PMID:16936857

  19. A Lightweight Hierarchical Activity Recognition Framework Using Smartphone Sensors

    PubMed Central

    Han, Manhyung; Bang, Jae Hun; Nugent, Chris; McClean, Sally; Lee, Sungyoung

    2014-01-01

    Activity recognition for the purposes of recognizing a user's intentions using multimodal sensors is becoming a widely researched topic largely based on the prevalence of the smartphone. Previous studies have reported the difficulty in recognizing life-logs by only using a smartphone due to the challenges with activity modeling and real-time recognition. In addition, recognizing life-logs is difficult due to the absence of an established framework which enables the use of different sources of sensor data. In this paper, we propose a smartphone-based Hierarchical Activity Recognition Framework which extends the Naïve Bayes approach for the processing of activity modeling and real-time activity recognition. The proposed algorithm demonstrates higher accuracy than the Naïve Bayes approach and also enables the recognition of a user's activities within a mobile environment. The proposed algorithm has the ability to classify fifteen activities with an average classification accuracy of 92.96%. PMID:25184486

  20. Optical fiber sensor having an active core

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1993-01-01

    An optical fiber is provided. The fiber is comprised of an active fiber core which produces waves of light upon excitation. A factor ka is identified and increased until a desired improvement in power efficiency is obtained. The variable a is the radius of the active fiber core and k is defined as 2 pi/lambda wherein lambda is the wavelength of the light produced by the active fiber core. In one embodiment, the factor ka is increased until the power efficiency stabilizes. In addition to a bare fiber core embodiment, a two-stage fluorescent fiber is provided wherein an active cladding surrounds a portion of the active fiber core having an improved ka factor. The power efficiency of the embodiment is further improved by increasing a difference between the respective indices of refraction of the active cladding and the active fiber core.

  1. ACFA 2020 - An FP7 project on active control of flexible fuel efficient aircraft configurations

    NASA Astrophysics Data System (ADS)

    Maier, R.

    2013-12-01

    This paper gives an overview about the project ACFA 2020 which is funded by the European Commission within the 7th framework program. The acronym ACFA 2020 stands for Active Control for Flexible Aircraft 2020. The project is dealing with the design of highly fuel efficient aircraft configurations and, in particular, on innovative active control concepts with the goal to reduce loads and structural weight. Major focus lays on blended wing body (BWB) aircraft. Blended wing body type aircraft configurations are seen as the most promising future concept to fulfill the so-called ACARE (Advisory Council for Aeronautics Research in Europe) vision 2020 goals in regards to reduce fuel consumption and external noise. The paper discusses in some detail the overall goals and how they are addressed in the workplan. Furthermore, the major achievements of the project are outlined and a short outlook on the remaining work is given.

  2. Absolute configuration of a new mosquito repellent, (+)-eucamalol and the repellent activity of its epimer.

    PubMed

    Satoh, A; Utamura, H; Nakade, T; Nishimura, H

    1995-06-01

    (+)-Eucamalol (1) and (-)-1-epi-eucamalol (2) were synthesized from (S)-(-)-perillaldehyde to determine the absolute configuration of 1, the structure of natural (+)-eucamalol being determined to be (1R,6R)-(+)-3-formyl-6-isopropyl-2-cyclohexen-1-ol. (+)-Eucamolol (1) and its 1-epimer (2) exhibited significant repellent activity against Aedes albopictus, and inhibited its feeding as well as DEET. PMID:7613002

  3. Advanced Sensor Concepts

    NASA Technical Reports Server (NTRS)

    Alhorn, D. C.; Howard, D. E.; Smith, D. A.

    2005-01-01

    The Advanced Sensor Concepts project was conducted under the Center Director's Discretionary Fund at the Marshall Space Flight Center. Its objective was to advance the technology originally developed for the Glovebox Integrated Microgravity Isolation Technology project. The objective of this effort was to develop and test several new motion sensors. To date, the investigators have invented seven new technologies during this endeavor and have conceived several others. The innovative basic sensor technology is an absolute position sensor. It employs only two active components, and it is simple, inexpensive, reliable, repeatable, lightweight, and relatively unobtrusive. Two sensors can be utilized in the same physical space to achieve redundancy. The sensor has micrometer positional accuracy and can be configured as a two- or three-dimensional sensor. The sensor technology has the potential to pioneer a new class of linear and rotary sensors. This sensor is the enabling technology for autonomous assembly of modular structures in space and on extraterrestrial locations.

  4. A militarily fielded thermal neutron activation sensor for landmine detection

    NASA Astrophysics Data System (ADS)

    Clifford, E. T. H.; McFee, J. E.; Ing, H.; Andrews, H. R.; Tennant, D.; Harper, E.; Faust, A. A.

    2007-08-01

    The Canadian Department of National Defence has developed a teleoperated, vehicle-mounted, multi-sensor system to detect anti-tank landmines on roads and tracks in peacekeeping operations. A key part of the system is a thermal neutron activation (TNA) sensor which is placed above a suspect location to within a 30 cm radius and confirms the presence of explosives via detection of the 10.835 MeV gamma ray associated with thermal neutron capture on 14N. The TNA uses a 100 μg252Cf neutron source surrounded by four 7.62 cm×7.62 cm NaI(Tl) detectors. The system, consisting of the TNA sensor head, including source, detectors and shielding, the high-rate, fast pulse processing electronics and the data processing methodology are described. Results of experiments to characterize detection performance are also described. The experiments have shown that anti-tank mines buried 10 cm or less can be detected in roughly a minute or less, but deeper mines and mines significantly displaced horizontally take considerably longer time. Mines as deep as 30 cm can be detected for long count times (1000 s). Four TNA detectors are now in service with the Canadian Forces as part of the four multi-sensor systems, making it the first militarily fielded TNA sensor and the first militarily fielded confirmation sensor for landmines. The ability to function well in adverse climatic conditions has been demonstrated, both in trials and operations.

  5. Frequency requirements for active earth observation sensors

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The foundation and rationale for the selection of microwave frequencies for active remote sensing usage and for subsequent use in determination of sharing criteria and allocation strategies for the WARC-79 are presented.

  6. Active Low Intrusion Hybrid Monitor for Wireless Sensor Networks

    PubMed Central

    Navia, Marlon; Campelo, Jose C.; Bonastre, Alberto; Ors, Rafael; Capella, Juan V.; Serrano, Juan J.

    2015-01-01

    Several systems have been proposed to monitor wireless sensor networks (WSN). These systems may be active (causing a high degree of intrusion) or passive (low observability inside the nodes). This paper presents the implementation of an active hybrid (hardware and software) monitor with low intrusion. It is based on the addition to the sensor node of a monitor node (hardware part) which, through a standard interface, is able to receive the monitoring information sent by a piece of software executed in the sensor node. The intrusion on time, code, and energy caused in the sensor nodes by the monitor is evaluated as a function of data size and the interface used. Then different interfaces, commonly available in sensor nodes, are evaluated: serial transmission (USART), serial peripheral interface (SPI), and parallel. The proposed hybrid monitor provides highly detailed information, barely disturbed by the measurement tool (interference), about the behavior of the WSN that may be used to evaluate many properties such as performance, dependability, security, etc. Monitor nodes are self-powered and may be removed after the monitoring campaign to be reused in other campaigns and/or WSNs. No other hardware-independent monitoring platforms with such low interference have been found in the literature. PMID:26393604

  7. Active Low Intrusion Hybrid Monitor for Wireless Sensor Networks.

    PubMed

    Navia, Marlon; Campelo, Jose C; Bonastre, Alberto; Ors, Rafael; Capella, Juan V; Serrano, Juan J

    2015-01-01

    Several systems have been proposed to monitor wireless sensor networks (WSN). These systems may be active (causing a high degree of intrusion) or passive (low observability inside the nodes). This paper presents the implementation of an active hybrid (hardware and software) monitor with low intrusion. It is based on the addition to the sensor node of a monitor node (hardware part) which, through a standard interface, is able to receive the monitoring information sent by a piece of software executed in the sensor node. The intrusion on time, code, and energy caused in the sensor nodes by the monitor is evaluated as a function of data size and the interface used. Then different interfaces, commonly available in sensor nodes, are evaluated: serial transmission (USART), serial peripheral interface (SPI), and parallel. The proposed hybrid monitor provides highly detailed information, barely disturbed by the measurement tool (interference), about the behavior of the WSN that may be used to evaluate many properties such as performance, dependability, security, etc. Monitor nodes are self-powered and may be removed after the monitoring campaign to be reused in other campaigns and/or WSNs. No other hardware-independent monitoring platforms with such low interference have been found in the literature. PMID:26393604

  8. Optimization of the activated sludge anoxic reactor configuration as a means to control nutrient removal kinetically.

    PubMed

    Plósz, Benedek Gy

    2007-04-01

    Factors influencing the determination of optimum reactor configuration for activated sludge denitrification are investigated in this paper. A kinetic optimization method is presented to evaluate optimal pre- and post-denitrification bioreactor stages. Applying the method developed, simulation studies were carried out to investigate the impacts of the ratio of the influent readily biodegradable and slowly biodegradable substrates and the oxygen entering the denitrification zones on the optimal anoxic reactor configuration. In addition, the paper describes the effects of the slowly biodegradable substrate on the denitrification efficiency using external substrate dosing, and it demonstrates kinetic considerations concerning the hydrolysis process. It has been shown that as a function of the biodegradable substrate composition, the stage system design with three optimized reactor compartments can effectively increase reaction rates in the denitrification zones, and can provide flexibility for varying operation conditions. PMID:17321565

  9. Predicting Nitrogen Fertilizer Recommendations for Corn using an Active Sensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active sensors, mounted on typical agricultural equipment, can be used to measure N (nitrogen) status in corn (Zea mays L.). This gives a producer the potential to improve N fertilizer recommendations that will reduce nitrate loss to the environment. This study examines the relationship between re...

  10. Developing Sidedress Nitrogen Recommendations for Corn using an Active Sensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active crop canopy reflectance sensors can be used during a sidedress N application to modify on-the-go fertilizer rates; but will this method be an improvement to current approaches to developing N recommendations? Our objective was to compare the potential for developing N recommendations for corn...

  11. Fusion of Smartphone Motion Sensors for Physical Activity Recognition

    PubMed Central

    Shoaib, Muhammad; Bosch, Stephan; Incel, Ozlem Durmaz; Scholten, Hans; Havinga, Paul J. M.

    2014-01-01

    For physical activity recognition, smartphone sensors, such as an accelerometer and a gyroscope, are being utilized in many research studies. So far, particularly, the accelerometer has been extensively studied. In a few recent studies, a combination of a gyroscope, a magnetometer (in a supporting role) and an accelerometer (in a lead role) has been used with the aim to improve the recognition performance. How and when are various motion sensors, which are available on a smartphone, best used for better recognition performance, either individually or in combination? This is yet to be explored. In order to investigate this question, in this paper, we explore how these various motion sensors behave in different situations in the activity recognition process. For this purpose, we designed a data collection experiment where ten participants performed seven different activities carrying smart phones at different positions. Based on the analysis of this data set, we show that these sensors, except the magnetometer, are each capable of taking the lead roles individually, depending on the type of activity being recognized, the body position, the used data features and the classification method employed (personalized or generalized). We also show that their combination only improves the overall recognition performance when their individual performances are not very high, so that there is room for performance improvement. We have made our data set and our data collection application publicly available, thereby making our experiments reproducible. PMID:24919015

  12. A built-in active sensor network for health monitoring of composite structures

    NASA Astrophysics Data System (ADS)

    Su, Zhongqing; Wang, Xiaoming; Chen, Zhiping; Ye, Lin; Wang, Dong

    2006-12-01

    An embedded sensor network technique was developed for improving the overall integrity of functionalized composite structures engaged in aircraft. A set of miniaturized piezoelectric wafers was designed and circuited to configure a built-in active actuator/sensor network, which was immobilized into multi-layered composite laminates. The propagation characteristics of Lamb waves generated and collected by this built-in sensor network in carbon fibre-reinforced composite laminates were investigated. The influence of a stiffener and of the excitation frequency on the propagation of the Lamb waves generated was evaluated. A study was carried out to assess delamination in CF/EP (carbon fibre/epoxy) woven laminates, by fusing information from multiple sensing paths of the embedded network on the basis of the Hilbert transform, signal correlation and probabilistic searching. An excellent identification capability indicates the considerable application potential of the proposed sensor network approach in providing high-fidelity data acquisition and condition monitoring for composite aircraft structures.

  13. Fiber Bragg grating strain sensors to monitor and study active volcanoes

    NASA Astrophysics Data System (ADS)

    Sorrentino, Fiodor; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvo; Giacomelli, Umberto; Grassi, Renzo; Maccioni, Enrico; Morganti, Mauro

    2016-04-01

    Stress and strain changes are among the best indicators of impending volcanic activity. In volcano geodesy, borehole volumetric strain-meters are mostly utilized. However, they are not easy to install and involve high implementation costs. Advancements in opto-electronics have allowed the development of low-cost sensors, reliable, rugged and compact, thus particularly suitable for field application. In the framework of the EC FP7 MED-SUV project, we have developed strain sensors based on the fiber Bragg grating (FBG) technology. In comparison with previous implementation of the FBG technology to study rock deformations, we have designed a system that is expected to offer a significantly higher resolution and accuracy in static measurements and a smooth dynamic response up to 100 Hz, implying the possibility to observe seismic waves. The system performances are tailored to suit the requirements of volcano monitoring, with special attention to power consumption and to the trade-off between performance and cost. Preliminary field campaigns were carried out on Mt. Etna (Italy) using a prototypal single-axis FBG strain sensor, to check the system performances in out-of-the-lab conditions and in the harsh volcanic environment (lack of mains electricity for power, strong diurnal temperature changes, strong wind, erosive ash, snow and ice during the winter time). We also designed and built a FBG strain sensor featuring a multi-axial configuration which was tested and calibrated in the laboratory. This instrument is suitable for borehole installation and will be tested on Etna soon.

  14. Sensors at Centrosomes Reveal Determinants of Local Separase Activity

    PubMed Central

    Agircan, Fikret Gurkan; Schiebel, Elmar

    2014-01-01

    Separase is best known for its function in sister chromatid separation at the metaphase-anaphase transition. It also has a role in centriole disengagement in late mitosis/G1. To gain insight into the activity of separase at centrosomes, we developed two separase activity sensors: mCherry-Scc1(142-467)-ΔNLS-eGFP-PACT and mCherry-kendrin(2059-2398)-eGFP-PACT. Both localize to the centrosomes and enabled us to monitor local separase activity at the centrosome in real time. Both centrosomal sensors were cleaved by separase before anaphase onset, earlier than the corresponding H2B-mCherry-Scc1(142-467)-eGFP sensor at chromosomes. This indicates that substrate cleavage by separase is not synchronous in the cells. Depletion of the proteins astrin or Aki1, which have been described as inhibitors of centrosomal separase, did not led to a significant activation of separase at centrosomes, emphasizing the importance of direct separase activity measurements at the centrosomes. Inhibition of polo-like kinase Plk1, on the other hand, decreased the separase activity towards the Scc1 but not the kendrin reporter. Together these findings indicate that Plk1 regulates separase activity at the level of substrate affinity at centrosomes and may explain in part the role of Plk1 in centriole disengagement. PMID:25299182

  15. A Comparison of Active and Passive Methods for Control of Hypersonic Boundary Layers on Airbreathing Configurations

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Nowak, Robert J.

    2003-01-01

    Active and passive methods for control of hypersonic boundary layers have been experimentally examined in NASA Langley Research Center wind tunnels on a Hyper-X model. Several configurations for forcing transition using passive discrete roughness elements and active mass addition, or blowing, methods were compared in two hypersonic facilities, the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air tunnels. Heat transfer distributions, obtained via phosphor thermography, shock system details, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. The comparisons between the active and passive methods for boundary layer control were conducted at test conditions that nearly match the nominal Mach 7 flight trajectory of an angle-of-attack of 2-deg and length Reynolds number of 5.6 million. For the passive roughness examination, the primary parametric variation was a range of trip heights within the calculated boundary layer thickness for several trip concepts. The prior passive roughness study resulted in a swept ramp configuration being selected for the Mach 7 flight vehicle that was scaled to be roughly 0.6 of the calculated boundary layer thickness. For the active jet blowing study, the blowing manifold pressure was systematically varied for each configuration, while monitoring the mass flow, to determine the jet penetration height with schlieren and transition movement with the phosphor system for comparison to the passive results. All the blowing concepts tested were adequate for providing transition onset near the trip location with manifold stagnation pressures on the order of 40 times the model static pressure or higher.

  16. CMOS VLSI Active-Pixel Sensor for Tracking

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata; Sun, Chao; Yang, Guang; Heynssens, Julie

    2004-01-01

    An architecture for a proposed active-pixel sensor (APS) and a design to implement the architecture in a complementary metal oxide semiconductor (CMOS) very-large-scale integrated (VLSI) circuit provide for some advanced features that are expected to be especially desirable for tracking pointlike features of stars. The architecture would also make this APS suitable for robotic- vision and general pointing and tracking applications. CMOS imagers in general are well suited for pointing and tracking because they can be configured for random access to selected pixels and to provide readout from windows of interest within their fields of view. However, until now, the architectures of CMOS imagers have not supported multiwindow operation or low-noise data collection. Moreover, smearing and motion artifacts in collected images have made prior CMOS imagers unsuitable for tracking applications. The proposed CMOS imager (see figure) would include an array of 1,024 by 1,024 pixels containing high-performance photodiode-based APS circuitry. The pixel pitch would be 9 m. The operations of the pixel circuits would be sequenced and otherwise controlled by an on-chip timing and control block, which would enable the collection of image data, during a single frame period, from either the full frame (that is, all 1,024 1,024 pixels) or from within as many as 8 different arbitrarily placed windows as large as 8 by 8 pixels each. A typical prior CMOS APS operates in a row-at-a-time ( grolling-shutter h) readout mode, which gives rise to exposure skew. In contrast, the proposed APS would operate in a sample-first/readlater mode, suppressing rolling-shutter effects. In this mode, the analog readout signals from the pixels corresponding to the windows of the interest (which windows, in the star-tracking application, would presumably contain guide stars) would be sampled rapidly by routing them through a programmable diagonal switch array to an on-chip parallel analog memory array. The

  17. Recognition of Human Activities Using Continuous Autoencoders with Wearable Sensors.

    PubMed

    Wang, Lukun

    2016-01-01

    This paper provides an approach for recognizing human activities with wearable sensors. The continuous autoencoder (CAE) as a novel stochastic neural network model is proposed which improves the ability of model continuous data. CAE adds Gaussian random units into the improved sigmoid activation function to extract the features of nonlinear data. In order to shorten the training time, we propose a new fast stochastic gradient descent (FSGD) algorithm to update the gradients of CAE. The reconstruction of a swiss-roll dataset experiment demonstrates that the CAE can fit continuous data better than the basic autoencoder, and the training time can be reduced by an FSGD algorithm. In the experiment of human activities' recognition, time and frequency domain feature extract (TFFE) method is raised to extract features from the original sensors' data. Then, the principal component analysis (PCA) method is applied to feature reduction. It can be noticed that the dimension of each data segment is reduced from 5625 to 42. The feature vectors extracted from original signals are used for the input of deep belief network (DBN), which is composed of multiple CAEs. The training results show that the correct differentiation rate of 99.3% has been achieved. Some contrast experiments like different sensors combinations, sensor units at different positions, and training time with different epochs are designed to validate our approach. PMID:26861319

  18. Optical Sensor/Actuator Locations for Active Structural Acoustic Control

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Palumbo, Daniel L.; Kincaid, Rex K.

    1998-01-01

    Researchers at NASA Langley Research Center have extensive experience using active structural acoustic control (ASAC) for aircraft interior noise reduction. One aspect of ASAC involves the selection of optimum locations for microphone sensors and force actuators. This paper explains the importance of sensor/actuator selection, reviews optimization techniques, and summarizes experimental and numerical results. Three combinatorial optimization problems are described. Two involve the determination of the number and position of piezoelectric actuators, and the other involves the determination of the number and location of the sensors. For each case, a solution method is suggested, and typical results are examined. The first case, a simplified problem with simulated data, is used to illustrate the method. The second and third cases are more representative of the potential of the method and use measured data. The three case studies and laboratory test results establish the usefulness of the numerical methods.

  19. Trichomes as sensors: detecting activity on the leaf surface.

    PubMed

    Tooker, John F; Peiffer, Michelle; Luthe, Dawn S; Felton, Gary W

    2010-01-01

    The dramatic movements of some carnivorous plants species are triggered by sensory structures derived from trichomes. While unusual plant species such as the Venus fly trap and sundews may be expected to have elaborate sensors to capture their insect prey, more modest plant species might not be expected to have similar sensory capabilities. Our recent work, however, has revealed that glandular trichomes on tomato (Solanum lycopersicum) appear to have a function similar to trigger hairs of carnivorous species, acting as "early warning" sensors. Using a combination of behavioral, molecular, and biochemical techniques, we determined that caterpillars, moths and mechanical disruption upregulate signaling molecules and defensive genes found in glandular trichomes. Importantly, we discovered that plants whose trichomes have been broken respond more vigorously when their defenses were induced. Taken together, our results suggest that glandular trichomes can act as sensors that detect activity on the leaf surface, and ready plants for herbivore attack. PMID:20592816

  20. Reward Contingency Modulates Neuronal Activity in Rat Septal Nuclei during Elemental and Configural Association Tasks

    PubMed Central

    Matsuyama, Nozomu; Uwano, Teruko; Hori, Etsuro; Ono, Taketoshi; Nishijo, Hisao

    2011-01-01

    It has been suggested that septal nuclei are important in the control of behavior during various reward and non-reward situations. In the present study, neuronal activity was recorded from rat septal nuclei during discrimination of conditioned sensory stimuli (CSs) of the medial forebrain bundle associated with or without a reward (sucrose solution or intracranial self-stimulation, ICSS). Rats were trained to lick a spout protruding close to the mouth just after a CS to obtain a reward stimulus. The CSs included both elemental and configural stimuli. In the configural condition, the reward contingency of the stimuli presented together was opposite to that of each elemental stimulus presented alone, although the same sensory stimuli were involved. Of the 72 responsive septal neurons, 18 responded selectively to the CSs predicting reward (CS+-related), four to the CSs predicting non-reward (CS0-related), nine to some CSs predicting reward or non-reward, and 15 non-differentially to all CSs. The remaining 26 neurons responded mainly during the ingestion/ICSS phase. A multivariate analysis of the septal neuronal responses to elemental and configural stimuli indicated that septal neurons encoded the CSs based on reward contingency, regardless of the stimulus physical properties and were categorized into three groups; CSs predicting the sucrose solution, CSs predicting a non-reward, and CSs predicting ICSS. The results suggest that septal nuclei are deeply involved in discriminating the reward contingency of environmental stimuli to manifest appropriate behaviors in response to changing stimuli. PMID:21633493

  1. Active pixel sensor array with electronic shuttering

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor)

    2002-01-01

    An active pixel cell includes electronic shuttering capability. The cell can be shuttered to prevent additional charge accumulation. One mode transfers the current charge to a storage node that is blocked against accumulation of optical radiation. The charge is sampled from a floating node. Since the charge is stored, the node can be sampled at the beginning and the end of every cycle. Another aspect allows charge to spill out of the well whenever the charge amount gets higher than some amount, thereby providing anti blooming.

  2. Use of polyurethane foam deformation sensor to record respiratory activity

    NASA Astrophysics Data System (ADS)

    Bredov, V. I.; Baranov, V. S.

    1980-05-01

    The sensor developed has some substantial advantages over other known types. It is highly sensitive over a wide range of strain loads. The level of the output signal is linearly related to the force exerted on it, and it is sufficient for direct recording without using amplifiers of electric signals. The sensor is based on elastic, spongy material, polyurethane foam (porolon) with current-conducting material on the pore surface, current-conducting carbon black or electrode paste. The elastic properties of the sensor are built in the actual base of the strain-sensitive element, which simplifies the construction substantially and increases the reliability of the unit. In order to test the possibility of using this sensor to examine respiratory function, human pneumograms were recorded with the subject in a calm state along with the respiratory activity of experimental animals (dogs). Samples of the respiratory curve are shown. The simplicity of design of the sensor makes it possible to use it in various physiological experiments.

  3. A CMOS active pixel sensor for retinal stimulation

    NASA Astrophysics Data System (ADS)

    Prydderch, Mark L.; French, Marcus J.; Mathieson, Keith; Adams, Christopher; Gunning, Deborah; Laudanski, Jonathan; Morrison, James D.; Moodie, Alan R.; Sinclair, James

    2006-02-01

    Degenerative photoreceptor diseases, such as age-related macular degeneration and retinitis pigmentosa, are the most common causes of blindness in the western world. A potential cure is to use a microelectronic retinal prosthesis to provide electrical stimulation to the remaining healthy retinal cells. We describe a prototype CMOS Active Pixel Sensor capable of detecting a visual scene and translating it into a train of electrical pulses for stimulation of the retina. The sensor consists of a 10 x 10 array of 100 micron square pixels fabricated on a 0.35 micron CMOS process. Light incident upon each pixel is converted into output current pulse trains with a frequency related to the light intensity. These outputs are connected to a biocompatible microelectrode array for contact to the retinal cells. The flexible design allows experimentation with signal amplitudes and frequencies in order to determine the most appropriate stimulus for the retina. Neural processing in the retina can be studied by using the sensor in conjunction with a Field Programmable Gate Array (FPGA) programmed to behave as a neural network. The sensor has been integrated into a test system designed for studying retinal response. We present the most recent results obtained from this sensor.

  4. Preliminary investigations of active pixel sensors in Nuclear Medicine imaging

    NASA Astrophysics Data System (ADS)

    Ott, Robert; Evans, Noel; Evans, Phil; Osmond, J.; Clark, A.; Turchetta, R.

    2009-06-01

    Three CMOS active pixel sensors have been investigated for their application to Nuclear Medicine imaging. Startracker with 525×525 25 μm square pixels has been coupled via a fibre optic stud to a 2 mm thick segmented CsI(Tl) crystal. Imaging tests were performed using 99mTc sources, which emit 140 keV gamma rays. The system was interfaced to a PC via FPGA-based DAQ and optical link enabling imaging rates of 10 f/s. System noise was measured to be >100e and it was shown that the majority of this noise was fixed pattern in nature. The intrinsic spatial resolution was measured to be ˜80 μm and the system spatial resolution measured with a slit was ˜450 μm. The second sensor, On Pixel Intelligent CMOS (OPIC), had 64×72 40 μm pixels and was used to evaluate noise characteristics and to develop a method of differentiation between fixed pattern and statistical noise. The third sensor, Vanilla, had 520×520 25 μm pixels and a measured system noise of ˜25e. This sensor was coupled directly to the segmented phosphor. Imaging results show that even at this lower level of noise the signal from 140 keV gamma rays is small as the light from the phosphor is spread over a large number of pixels. Suggestions for the 'ideal' sensor are made.

  5. Nitrogen-containing bibenzyls from Pleione bulbocodioides: absolute configurations and biological activities.

    PubMed

    Li, Yuan; Zhang, Fan; Wu, Ze-Hong; Zeng, Ke-Wu; Zhang, Chen; Jin, Hong-Wei; Zhao, Ming-Bo; Jiang, Yong; Li, Jun; Tu, Peng-Fei

    2015-04-01

    Four new pyrrolidone substituted bibenzyls, dusuanlansins A-D (1-4) were isolated from the pseudo bulbs of Pleione bulbocodioides, along with 19 known compounds (5-23). Compounds 1-4 are two pairs of epimers of pyrrolidone substituted bibenzyls, which were separated successfully by a Chiralcel OD-RH C18 column. Their absolute configurations were elucidated by calculated ECD. Biological investigations showed that compounds 5 and 7 exhibited potent anti-inflammatory activities on LPS-stimulated NO production in BV-2 microglial cells, with IC50 values of 2.46 and 3.14μM, respectively. PMID:25647325

  6. Structure, absolute configuration, and antidiarrheal activity of a thymol derivative from Ageratina cylindrica.

    PubMed

    Bustos-Brito, Celia; Sánchez-Castellanos, Mariano; Esquivel, Baldomero; Calderón, José S; Calzada, Fernando; Yepez-Mulia, Lilian; Hernández-Barragán, Angelina; Joseph-Nathan, Pedro; Cuevas, Gabriel; Quijano, Leovigildo

    2014-02-28

    The leaves of Ageratina cylindrica afforded a thymol derivative that was characterized by physical and spectroscopical methods as (8S)-8,9-epoxy-6-hydroxy-l0-benzoyloxy-7-oxothymol isobutyrate (1). The absolute configuration of 1 was established as 8S by vibrational circular dichroism spectroscopy in combination with density functional theory calculations and by evaluation of the Flack and Hooft X-ray parameters. Compound 1 showed weak antiprotozoal activity against Entamoeba histolytica and Giardia lamblia trophozoites and a high inhibitory effect on hyperpropulsive movement of the small intestine in rats. PMID:24502360

  7. Configurations of Activity: From the Coupling of Individual Actions to the Emergence of Collective Activity. A Study of Mathematics Teaching Situation in Primary School

    ERIC Educational Resources Information Center

    Veyrunes, Philippe; Gal-Petitfaux, Nathalie; Durand, Marc

    2009-01-01

    This article presents and uses the notion of configuration of activity, which extends the Norbert Elias's original concept of social configuration based on the study and analysis of individual and collective activity. Although this concept embraces all types of social activities, in the present study the authors used it to describe and analyse…

  8. Wireless sensor networks for active vibration control in automobile structures

    NASA Astrophysics Data System (ADS)

    Mieyeville, Fabien; Ichchou, Mohamed; Scorletti, Gérard; Navarro, David; Du, Wan

    2012-07-01

    Wireless sensor networks (WSNs) are nowadays widely used in monitoring and tracking applications. This paper presents the feasibility of using WSNs in active vibration control strategies. The method employed here involves active-structural acoustic control using piezoelectric sensors distributed on a car structure. This system aims at being merged with a WSN whose head node collects data and processes control laws so as to command piezoelectric actuators wisely placed on the structure. We will study the feasibility of implementing WSNs in active vibration control and introduce a complete design methodology to optimize hardware/software and control law synergy in mechatronic systems. A design space exploration will be conducted so as to identify the best WSN platform and the resulting impact on control.

  9. Active resonant subwavelength grating for scannerless range imaging sensors.

    SciTech Connect

    Kemme, Shanalyn A.; Nellums, Robert O.; Boye, Robert R.; Peters, David William

    2006-11-01

    In this late-start LDRD, we will present a design for a wavelength-agile, high-speed modulator that enables a long-term vision for the THz Scannerless Range Imaging (SRI) sensor. It takes the place of the currently-utilized SRI micro-channel plate which is limited to photocathode sensitive wavelengths (primarily in the visible and near-IR regimes). Two of Sandia's successful technologies--subwavelength diffractive optics and THz sources and detectors--are poised to extend the capabilities of the SRI sensor. The goal is to drastically broaden the SRI's sensing waveband--all the way to the THz regime--so the sensor can see through image-obscuring, scattering environments like smoke and dust. Surface properties, such as reflectivity, emissivity, and scattering roughness, vary greatly with the illuminating wavelength. Thus, objects that are difficult to image at the SRI sensor's present near-IR wavelengths may be imaged more easily at the considerably longer THz wavelengths (0.1 to 1mm). The proposed component is an active Resonant Subwavelength Grating (RSG). Sandia invested considerable effort on a passive RSG two years ago, which resulted in a highly-efficient (reflectivity greater than gold), wavelength-specific reflector. For this late-start LDRD proposal, we will transform the passive RSG design into an active laser-line reflector.

  10. Active Control of Noise Using Actuator/Sensor Arrays

    NASA Technical Reports Server (NTRS)

    Lindner, Douglas K.; Winder, Patrice; Kirby, George

    1996-01-01

    Current research in smart structures is directed toward the integration of many actuators and sensors into a material. In this paper we investigate the possibility of using this instrumentation for active noise control from a vibrating structures. Current technology for reducing radiated sound is limited by the instrumentation for the control system. These control systems employ relatively small numbers of sensors and actuators. Hence, these control systems must rely on a model of the structure to estimate and control the global vibrations that contribute to the far field pressure. For complex, realistic structures the development of such a model is a formidable task. The model is a limiting factor in the continuing development of structural acoustics. In this paper we propose to increase the number of actuators and sensors of a smart material to offset the complexity of the model used for control design. The sensor arrays will be used to directly sense the shape of the structure rather than using a model of the structures to indirectly sense the shape of the structure. The actuator array is used to apply distributed forces to the structure, rather than using the structure itself as a load path. A control system for the active cancellation of sound is derived from standard control system methodologies.

  11. Improved thermal neutron activation sensor for detection of bulk explosives

    NASA Astrophysics Data System (ADS)

    McFee, John E.; Faust, Anthony A.; Andrews, H. Robert; Clifford, Edward T. H.; Mosquera, Cristian M.

    2012-06-01

    Defence R&D Canada - Suffield and Bubble Technology Industries have been developing thermal neutron activation (TNA) sensors for detection of buried bulk explosives since 1994. First generation sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on the ILDS teleoperated, vehicle-mounted, multi-sensor anti-tank landmine detection systems. The first generation TNA could detect anti-tank mines buried 10 cm or less in no more than a minute, but deeper mines and those significantly displaced horizontally required considerably longer times. Mines as deep as 30 cm could be detected with long counting times (1000 s). The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. This improved sensitivity can translate to either decreased counting times, decreased minimum detectable explosive quantities, increased maximum sensor-to-target displacement, or a trade off among all three. Experiments to characterize the performance of the latest generation TNA in detecting buried landmines and IEDs hidden in culverts were conducted during 2011. This paper describes the second generation system. The experimental setup and methodology are detailed and preliminary comparisons between the performance of first and second generation systems are presented.

  12. Feasibility of simultaneous operation of passive remote microwave sensors and active services occupying adjacent frequency bands

    NASA Technical Reports Server (NTRS)

    Sue, M. K.

    1982-01-01

    To ensure proper sensor operations, it is necessary to understand the situation of potential interference to sensors due to active equipment sharing common frequency bands as well as equipment occupying adjacent bands. The feasibility of sharing common frequency bands between passive sensors and other active services was analyzed. Potential interference to sensors due to equipment in bands adjacent to sensor frequency bands is examined and criteria to avoid interference is developed.

  13. Manipulation of acoustic focusing with an active and configurable planar metasurface transducer

    NASA Astrophysics Data System (ADS)

    Zhao, Jiajun; Ye, Huapeng; Huang, Kun; Chen, Zhi Ning; Li, Baowen; Qiu, Cheng-Wei

    2014-09-01

    It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding.

  14. Manipulation of acoustic focusing with an active and configurable planar metasurface transducer.

    PubMed

    Zhao, Jiajun; Ye, Huapeng; Huang, Kun; Chen, Zhi Ning; Li, Baowen; Qiu, Cheng-Wei

    2014-01-01

    It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding. PMID:25174409

  15. Manipulation of acoustic focusing with an active and configurable planar metasurface transducer

    PubMed Central

    Zhao, Jiajun; Ye, Huapeng; Huang, Kun; Chen, Zhi Ning; Li, Baowen; Qiu, Cheng-Wei

    2014-01-01

    It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding. PMID:25174409

  16. Integrative application of active controls (IAAC) technology to an advanced subsonic transport project. Initial act configuration design study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The performance and economic benefits of a constrained application of Active Controls Technology (ACT) are identified, and the approach to airplane design is established for subsequent steps leading to the development of a less constrained final ACT configuration. The active controls configurations are measured against a conventional baseline configuration, a state-of-the-art transport, to determine whether the performance and economic changes resulting from ACT merit proceeding with the project. The technology established by the conventional baseline configuration was held constant except for the addition of ACT. The wing, with the same planform, was moved forward on the initial ACT configuration to move the loading range aft relative to the wing mean aerodynamic chord. Wing trailing-edge surfaces and surface controls also were reconfigured for load alleviation and structural stabilization.

  17. Fluorescence-Based Sensor for Monitoring Activation of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Wallace, William T.; Jeevarajan, Antony S.

    2012-01-01

    This sensor unit is designed to determine the level of activation of lunar dust or simulant particles using a fluorescent technique. Activation of the surface of a lunar soil sample (for instance, through grinding) should produce a freshly fractured surface. When these reactive surfaces interact with oxygen and water, they produce hydroxyl radicals. These radicals will react with a terephthalate diluted in the aqueous medium to form 2-hydroxyterephthalate. The fluorescence produced by 2-hydroxyterephthalate provides qualitative proof of the activation of the sample. Using a calibration curve produced by synthesized 2-hydroxyterephthalate, the amount of hydroxyl radicals produced as a function of sample concentration can also be determined.

  18. Activity-based intelligence tipping and cueing using polarimetric sensors

    NASA Astrophysics Data System (ADS)

    Lewis, Christian M.; Messinger, David; Gartley, Michael G.

    2014-05-01

    Activity Based Intelligence (ABI) is the derivation of information from the composite of a series of individual actions being recorded over a period of time. Due to its temporal nature, ABI is usually developed from Motion Imagery (MI) or Full Motion Video (FMV) taken of a given scene. One of today's common issues is sifting through such large volumes of temporal data. Here we propose using a technique known as tipping an cueing to alleviate the need to manually sift through said data. Being able to tip the analysts or automated algorithm towards a particular person or object in the data is useful in reducing search time. We propose using a polarimetric sensor to identify objects of interest, in a scene where their signature would be unusual. Once identified, this data will be used to cue a FMV RGB sensor to track the object and determine the activities being executed by the person bringing the object into the scene.

  19. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-03-08

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (NM) impedance technique are sighted and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency EIM impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acoustic-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens, (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  20. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-02-29

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (E/M) impedance technique are cited and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency E/M impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acousto-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  1. Active sensors for health monitoring of aging aerospace structures

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Redmond, James M.; Roach, Dennis P.; Rackow, Kirk

    2000-06-01

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (E/M) impedance technique are cited and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high frequency E/M impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acousto- ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens, (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  2. Motion Sensor Reactivity in Physically Active Young Adults

    ERIC Educational Resources Information Center

    Behrens, Timothy K.; Dinger, Mary K.

    2007-01-01

    The purpose of this study was to examine whether young adults changed their physical activity (PA) behavior when wearing motion sensors. PA patterns of 119 young adults (M age = 20.82 years, SD = 1.50, M body mass index = 23.93 kg/m[superscript 2] , SD = 4.05) were assessed during 2 consecutive weeks. In Week 1, participants wore an accelerometer.…

  3. Quantum dot-based concentric FRET configuration for the parallel detection of protease activity and concentration.

    PubMed

    Wu, Miao; Petryayeva, Eleonora; Algar, W Russ

    2014-11-18

    Protease expression, activity, and inhibition play crucial roles in a multitude of biological processes; however, these three aspects of their function are difficult for any one bioanalytical probe to measure. To help address this challenge, we report a multifunctional concentric Förster resonance energy transfer (FRET) configuration that combines two modes of biorecognition using aptamers and peptide substrates coassembled to a central semiconductor quantum dot (QD). The aptamer is sensitive to the concentration of protease and the peptide is sensitive to its hydrolytic activity. The role of the QD is to serve as a nanoscale scaffold and initial donor for energy transfer with both Cyanine 3 (Cy3) and Alexa Fluor 647 (A647) fluorescent dyes associated with the aptamer and peptide, respectively. Using thrombin as a model protease, we show that a ratiometric analysis of the emission from the QD, Cy3, and A647 permits discrimination between thrombin and thrombin-like activity, and distinguishes between active, reversibly inhibited, and irreversibly inhibited thrombin. Reliable quantitative results were obtained from a kinetic analysis of the changes in FRET. This concentric FRET format, which capitalizes on both the physical and optical properties of QDs, should be adaptable to other protease targets for which both peptide substrates and binding aptamers are known. It is thus expected to become valuable a tool for the real-time analysis of protease activity and regulation. PMID:25361050

  4. High temperature sensor/microphone development for active noise control

    NASA Technical Reports Server (NTRS)

    Shrout, Thomas R.

    1993-01-01

    The industrial and scientific communities have shown genuine interest in electronic systems which can operate at high temperatures, among which are sensors to monitor noise, vibration, and acoustic emissions. Acoustic sensing can be accomplished by a wide variety of commercially available devices, including: simple piezoelectric sensors, accelerometers, strain gauges, proximity sensors, and fiber optics. Of the several sensing mechanisms investigated, piezoelectrics were found to be the most prevalent, because of their simplicity of design and application and, because of their high sensitivity over broad ranges of frequencies and temperature. Numerous piezoelectric materials are used in acoustic sensors today; but maximum use temperatures are imposed by their transition temperatures (T(sub c)) and by their resistivity. Lithium niobate, in single crystal form, has the highest operating temperature of any commercially available material, 650 C; but that is not high enough for future requirements. Only two piezoelectric materials show potential for use at 1000 C; AlN thin film reported to be piezoactive at 1150 C, and perovskite layer structure (PLS) materials, which possess among the highest T(sub c) (greater than 1500 C) reported for ferroelectrics. A ceramic PLS composition was chosen. The solid solution composition, 80% strontium niobate (SN) and 20% strontium tantalate (STa), with a T(sub c) approximately 1160 C, was hot forged, a process which concurrently sinters and renders the plate-like grains into a highly oriented configuration to enhance piezo properties. Poled samples of this composition showed coupling (k33) approximately 6 and piezoelectric strain constant (d33) approximately 3. Piezoactivity was seen at 1125 C, the highest temperature measurement reported for a ferroelectric ceramic. The high temperature piezoelectric responses of this, and similar PLS materials, opens the possibility of their use in electronic devices operating at temperatures up to

  5. Motion Sensor Use for Physical Activity Data: Methodological Considerations

    PubMed Central

    McCarthy, Margaret; Grey, Margaret

    2015-01-01

    Background Physical inactivity continues to be a major risk factor for cardiovascular disease, and only one half of adults in the United States meet physical activity (PA) goals. PA data are often collected for surveillance or for measuring change after an intervention. One of the challenges in PA research is quantifying exactly how much and what type of PA is taking place—especially because self-report instruments have inconsistent validity. Objective The purpose is to review the elements to consider when collecting PA data via motion sensors, including the difference between PA and exercise; type of data to collect; choosing the device; length of time to monitor PA; instructions to the participants; and interpretation of the data. Methods The current literature on motion sensor research was reviewed and synthesized to summarize relevant considerations when using a motion sensor to collect PA data. Results Exercise is a division of PA that is structured, planned, and repetitive. Pedometer data includes steps taken, and calculated distance and energy expenditure. Accelerometer data includes activity counts and intensity. The device chosen depends on desired data, cost, validity, and ease of use. Reactivity to the device may influence the duration of data collection. Instructions to participants may vary depending on purpose of the study. Experts suggest pedometer data be reported as steps—since that is the direct output—and distance traveled and energy expenditure are estimated values. Accelerometer count data may be analyzed to provide information on time spent in moderate or vigorous activity. Discussion Thoughtful decision making about PA data collection using motion sensor devices is needed to advance nursing science. PMID:26126065

  6. Implementation study of wearable sensors for activity recognition systems

    PubMed Central

    Ghassemian, Mona

    2015-01-01

    This Letter investigates and reports on a number of activity recognition methods for a wearable sensor system. The authors apply three methods for data transmission, namely ‘stream-based’, ‘feature-based’ and ‘threshold-based’ scenarios to study the accuracy against energy efficiency of transmission and processing power that affects the mote's battery lifetime. They also report on the impact of variation of sampling frequency and data transmission rate on energy consumption of motes for each method. This study leads us to propose a cross-layer optimisation of an activity recognition system for provisioning acceptable levels of accuracy and energy efficiency. PMID:26609413

  7. Recognition of Human Activities Using Continuous Autoencoders with Wearable Sensors

    PubMed Central

    Wang, Lukun

    2016-01-01

    This paper provides an approach for recognizing human activities with wearable sensors. The continuous autoencoder (CAE) as a novel stochastic neural network model is proposed which improves the ability of model continuous data. CAE adds Gaussian random units into the improved sigmoid activation function to extract the features of nonlinear data. In order to shorten the training time, we propose a new fast stochastic gradient descent (FSGD) algorithm to update the gradients of CAE. The reconstruction of a swiss-roll dataset experiment demonstrates that the CAE can fit continuous data better than the basic autoencoder, and the training time can be reduced by an FSGD algorithm. In the experiment of human activities’ recognition, time and frequency domain feature extract (TFFE) method is raised to extract features from the original sensors’ data. Then, the principal component analysis (PCA) method is applied to feature reduction. It can be noticed that the dimension of each data segment is reduced from 5625 to 42. The feature vectors extracted from original signals are used for the input of deep belief network (DBN), which is composed of multiple CAEs. The training results show that the correct differentiation rate of 99.3% has been achieved. Some contrast experiments like different sensors combinations, sensor units at different positions, and training time with different epochs are designed to validate our approach. PMID:26861319

  8. Using an Active Pixel Sensor In A Vertex Detector

    SciTech Connect

    Matis, Howard S.; Bieser, Fred; Chen, Yandong; Gareus, Robin; Kleinfelder, Stuart; Oldenburg, Markus; Retiere, Fabrice; Ritter, HansGeorg; Wieman, Howard H.; Wurzel, Samuel E.; Yamamoto, Eugene

    2004-04-22

    Research has shown that Active Pixel CMOS sensors can detect charged particles. We have been studying whether this process can be used in a collider environment. In particular, we studied the effect of radiation with 55 MeV protons. These results show that a fluence of about 2 x 10{sup 12} protons/cm{sup 2} reduces the signal by a factor of two while the noise increases by 25%. A measurement 6 months after exposure shows that the silicon lattice naturally repairs itself. Heating the silicon to 100 C reduced the shot noise and increased the collected charge. CMOS sensors have a reduced signal to noise ratio per pixel because charge diffuses to neighboring pixels. We have constructed a photogate to see if this structure can collect more charge per pixel. Results show that a photogate does collect charge in fewer pixels, but it takes about 15 ms to collect all of the electrons produced by a pulse of light.

  9. Active wireless temperature sensors for aerospace thermal protection systems

    NASA Astrophysics Data System (ADS)

    Milos, Frank S.; Karunaratne, K. S. G.

    2003-07-01

    Vehicle system health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles in order to reduce life-cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to advance inspection and health management technologies for thermal protection systems. This paper summarizes a joint effort by NASA Ames and Korteks to develop active "wireless" sensors that can be embedded in the thermal protection system to monitor subsurface temperature histories. These devices are thermocouples integrated with radio-frequency identification circuits to enable non-contact communication of temperature data through aerospace thermal protection materials. Two generations of prototype sensors are discussed. The advanced prototype collects data from three type-k thermocouples attached to a 25-mm square integrated circuit and can communicate through 7 to 10 cm thickness of thermal protection materials.

  10. Active Wireless Temperature Sensors for Aerospace Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Karunaratne, K.; Arnold, Jim (Technical Monitor)

    2002-01-01

    Health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles in order to reduce life-cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to advance inspection and health management technologies for thermal protection systems. This paper summarizes a joint project between NASA Ames and Korteks to develop active wireless sensors that can be embedded in the thermal protection system to monitor sub-surface temperature histories. These devices are thermocouples integrated with radio-frequency identification circuitry to enable acquisition and non-contact communication of temperature data through aerospace thermal protection materials. Two generations of prototype sensors are discussed. The advanced prototype collects data from three type-k thermocouples attached to a 2.54-cm square integrated circuit.

  11. Polymer optical fiber grating as water activity sensor

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Webb, David J.

    2014-05-01

    Controlling the water content within a product has long been required in the chemical processing, agriculture, food storage, paper manufacturing, semiconductor, pharmaceutical and fuel industries. The limitations of water content measurement as an indicator of safety and quality are attributed to differences in the strength with which water associates with other components in the product. Water activity indicates how tightly water is "bound," structurally or chemically, in products. Water absorption introduces changes in the volume and refractive index of poly(methyl methacrylate) PMMA. Therefore for a grating made in PMMA based optical fiber, its wavelength is an indicator of water absorption and PMMA thus can be used as a water activity sensor. In this work we have investigated the performance of a PMMA based optical fiber grating as a water activity sensor in sugar solution, saline solution and Jet A-1 aviation fuel. Samples of sugar solution with sugar concentration from 0 to 8%, saline solution with concentration from 0 to 22%, and dried (10ppm), ambient (39ppm) and wet (68ppm) aviation fuels were used in experiments. The corresponding water activities are measured as 1.0 to 0.99 for sugar solution, 1.0 to 0.86 for saline solution, and 0.15, 0.57 and 1.0 for the aviation fuel samples. The water content in the measured samples ranges from 100% (pure water) to 10 ppm (dried aviation fuel). The PMMA based optical fiber grating exhibits good sensitivity and consistent response, and Bragg wavelength shifts as large as 3.4 nm when the sensor is transferred from dry fuel to wet fuel.

  12. Effects of overhead work configuration on muscle activity during a simulated drilling task.

    PubMed

    Maciukiewicz, Jacquelyn M; Cudlip, Alan C; Chopp-Hurley, Jaclyn N; Dickerson, Clark R

    2016-03-01

    Overhead work is a known catalyst for occupational shoulder injury. Industrial workers must often adopt awkward overhead postures and loading profiles to complete required tasks, potentially elevating injury risk. This research examined the combined influence of multiple overhead working parameters on upper extremity muscular demands for an industrial drilling application. Twenty-two right-handed males completed 24 unilateral and bilateral overhead work exertions stratified by direction (upward, forward), point of force application (15, 30 and 45 cm in front of the body), and whole-body posture (seated, standing). The dependency of electromyographic (EMG) activity on several factors was established. Significant two-way interactions existed between point of force application and direction (p < 0.0001) and direction and whole body posture (p < 0.0001). An average increase in muscular activity of 6.5% maximal voluntary contraction (MVC) occurred for the contralateral limb when the bilateral task was completed, compared to unilateral tasks, with less than a 1% MVC increase for the active limb. These findings assist evidence-based approaches to overhead tasks, specifically in the construction industry. A bilateral task configuration is recommended to reduce glenohumeral stability demands. As well, particularly for tasks with a far reach distance, design tasks to promote a forward directed exertion. The considerable inter-subject variability suggests that fixed heights are not ideal, and should be avoided, and where this is not possible reaches should be reduced. PMID:26674399

  13. Analysis of ultra-high sensitivity configuration in chip-integrated photonic crystal microcavity bio-sensors

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Hosseini, Amir; Xu, Xiaochuan; Zhu, Liang; Zou, Yi; Chen, Ray T.

    2014-05-01

    We analyze the contributions of quality factor, fill fraction, and group index of chip-integrated resonance microcavity devices, to the detection limit for bulk chemical sensing and the minimum detectable biomolecule concentration in biosensing. We analyze the contributions from analyte absorbance, as well as from temperature and spectral noise. Slow light in two-dimensional photonic crystals provide opportunities for significant reduction of the detection limit below 1 × 10-7 RIU (refractive index unit) which can enable highly sensitive sensors in diverse application areas. We demonstrate experimentally detected concentration of 1 fM (67 fg/ml) for the binding between biotin and avidin, the lowest reported till date.

  14. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sensors. 1211.13 Section 1211.13 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT... § 1211.13 Inherent force activated secondary door sensors. (a) Normal operation test. (1) A force activated door sensor of a door system installed according to the installation instructions shall...

  15. A CMOS Active Pixel Sensor for Charged Particle Detection

    SciTech Connect

    Matis, Howard S.; Bieser, Fred; Kleinfelder, Stuart; Rai, Gulshan; Retiere, Fabrice; Ritter, Hans George; Singh, Kunal; Wurzel, Samuel E.; Wieman, Howard; Yamamoto, Eugene

    2002-12-02

    Active Pixel Sensor (APS) technology has shown promise for next-generation vertex detectors. This paper discusses the design and testing of two generations of APS chips. Both are arrays of 128 by 128 pixels, each 20 by 20 {micro}m. Each array is divided into sub-arrays in which different sensor structures (4 in the first version and 16 in the second) and/or readout circuits are employed. Measurements of several of these structures under Fe{sup 55} exposure are reported. The sensors have also been irradiated by 55 MeV protons to test for radiation damage. The radiation increased the noise and reduced the signal. The noise can be explained by shot noise from the increased leakage current and the reduction in signal is due to charge being trapped in the epi layer. Nevertheless, the radiation effect is small for the expected exposures at RHIC and RHIC II. Finally, we describe our concept for mechanically supporting a thin silicon wafer in an actual detector.

  16. Optical Breath Gas Sensor for Extravehicular Activity Application

    NASA Technical Reports Server (NTRS)

    Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Pilgrim, Jeffrey S.; Chullen, Cinda; Falconi, Eric A.; McMillin, Summer

    2013-01-01

    The function of the infrared gas transducer used during extravehicular activity in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation portable life support system (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Space Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode spectrometer based on wavelength modulation spectroscopy is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode-based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen channel using a vertical cavity surface emitting laser. Both prototypes are controlled digitally with a field-programmable gate array/microcontroller architecture. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU.

  17. Development of Active Catheter,Active Guide Wire and Micro Sensor Systems

    PubMed Central

    Haga, Y.; Mineta, T.; Totsu, K.; Makishi, W.; Esashi, M.

    2001-01-01

    Summary Active catheters and active guide wires which move like a snake have been developed for catheter-based minimally invasive diagnosis and therapy. Communication and control IC chips in the active catheter reduce the number of lead wires for control. The active catheter can be not only bent but also torsioned and extended. An ultra minature fiber-optic pressure sensor; a forward-looking ultrasonic probe and a magnetic position and orientation sensor have been developed for catheters and guide wires. These moving mechanisms and several sensors which are fitted near the tip of the catheter and the guide wire will provide detailed information near the tip and enable delicate and effective catheter intervention. PMID:20663389

  18. Nanostructures and porous silicon: activity and phase transformation in sensors and photocatalytic reactors

    NASA Astrophysics Data System (ADS)

    Gole, James L.; Lewis, Stephen E.; Fedorov, Andrei; Prokes, Sharka

    2005-08-01

    Porous interfaces are being transformed within the framework of nanotechnology to develop highly efficient sensors, nanostructure modified microreactors, and active battery electrodes. We demonstrate the rapid and reversible sensing of HCl, NH3, CO, SO2, H2S, and NOx at or below the ppm level. Gold and tin-based nanostructured coatings are introduced to improve the detection of NH3, CO, and NOx as these coatings form the initial basis for introducing significant selectivity. These sensor suites are being extended to develop microreactors, with a goal to introduce quantum dot (QD) based photocatalysts within the porous interface structure. Highly efficient, visible light absorbing, anatase TiO2-xNx nanophotocatalysts have been formed in seconds at room temperature via the direct nitridation of anatase TiO2 nanocolloids. A tunability throughout the visible is found to depend upon the degree of nanoparticle agglomeration and upon the ready ability to seed these nanoparticles with metal (metal ions) including Pt, Co, and Ni. This metal ion seeding also leads to unique efficient phase transformations, including that of anatase to rutile TiO2, at room temperature. The visible light absorbing photocatalysts readily photodegrade methylene blue and gaseous ethylene. They can be transformed from liquids to gels and, in addition, can be placed on the surfaces of sensor and microreactor based configurations 1) to produce an improved photocatalytically induced solar based sensor response, and 2) with a goal to facilitate catalytically induced disinfection of airborne pathogens. In contrast to the nitridation process which is facile at the nanoscale, we find little or no direct nitridation of micrometer sized anatase or rutile TiO2 powders at room temperature. Thus, we illustrate an example of how a traversal to the nanoscale can vastly improve the efficiency for producing important submicron particles.

  19. Activity of Daily Living assessment through wireless sensor data.

    PubMed

    Qing Zhang; Karunanithi, Mohan; Bradford, Dana; van Kasteren, Yasmin

    2014-01-01

    Activity of Daily Living has become a clinical de facto instrument to assess daily functional status of older people living independently at home. Almost all ADLs scales are based on subjective assessment of clinical staff and self-reported responses of the elderly person. A great deal of variability in ADL assessment is likely due to the different cultural beliefs, language and education, and over-assessment of personal capability to potentially avoid negative consequences. This paper proposes automatic and objective ADLs assessment as key component of a technology platform that supports older people to live independently in their home, called Smarter Safer Homes. The objective ADL assessment is achieved through communicating data from simple non-intrusive, wireless sensors placed in a home environment. Pilot sensor data sets were collected over six months from nine independent living homes of participants aged 70+ year. The application of a clustering based, unsupervised learning method on these data sets demonstrates the potential to automatically detect five domains of activity contributing to functional independence. Furthermore, the method provides features that support elderlys self-monitoring of daily activities more regularly, that could provide the potential for timely and early intervention from family and carers. PMID:25570315

  20. Symmetry adapted cluster-configuration interaction calculation of the photoelectron spectra of famous biological active steroids

    NASA Astrophysics Data System (ADS)

    Abyar, Fatemeh; Farrokhpour, Hossein

    2014-11-01

    The photoelectron spectra of some famous steroids, important in biology, were calculated in the gas phase. The selected steroids were 5α-androstane-3,11,17-trione, 4-androstane-3,11,17-trione, cortisol, cortisone, corticosterone, dexamethasone, estradiol and cholesterol. The calculations were performed employing symmetry-adapted cluster/configuration interaction (SAC-CI) method using the 6-311++G(2df,pd) basis set. The population ratios of conformers of each steroid were calculated and used for simulating the photoelectron spectrum of steroid. It was found that more than one conformer contribute to the photoelectron spectra of some steroids. To confirm the calculated photoelectron spectra, they compared with their corresponding experimental spectra. There were no experimental gas phase Hesbnd I photoelectron spectra for some of the steroids of this work in the literature and their calculated spectra can show a part of intrinsic characteristics of this molecules in the gas phase. The canonical molecular orbitals involved in the ionization of each steroid were calculated at the HF/6-311++g(d,p) level of theory. The spectral bands of each steroid were assigned by natural bonding orbital (NBO) calculations. Knowing the electronic structures of steroids helps us to understand their biological activities and find which sites of steroid become active when a modification is performing under a biological pathway.

  1. Comparison of dielectric materials for the activation of a macro-scale hinge configuration

    NASA Astrophysics Data System (ADS)

    Jordi, C.; Schmidt, A.; Kovacs, G.; Ermanni, Paolo

    2011-04-01

    While much of the research on dielectric elastomer actuators used to concentrate on VHB 4910 as dielectric material, lately many new, specifically developed materials have come into focus. The acrylic VHB has been thoroughly characterized in a macro-scale agonist-antagonist configuration on an active hinge. This was carried out with the aim of using it on an airship, which was activated, undulating body and a fin and thus propelled in a fish-like manner. The concept was proved in flight, but still lifetime and viscosity of the actuators and the time-costing fabrication due to the necessary large pre-stretches of the dielectric membrane caused severe inconveniences. In order to evaluate the usability of other materials for this specific purpose, two other materials, a corrugated silicone with silver electrodes (by PolyPower) and an acrylic with interpenetrating network (IPN) developed by Pei et al. were characterized under similar conditions. The influence of the material on performance and design of the actuators and the conclusions for the use of the materials on the airship (and on applications with similar performance requirements) are presented.

  2. Cysteine redox sensor in PKGIa enables oxidant-induced activation.

    PubMed

    Burgoyne, Joseph R; Madhani, Melanie; Cuello, Friederike; Charles, Rebecca L; Brennan, Jonathan P; Schröder, Ewald; Browning, Darren D; Eaton, Philip

    2007-09-01

    Changes in the concentration of oxidants in cells can regulate biochemical signaling mechanisms that control cell function. We have found that guanosine 3',5'-monophosphate (cGMP)-dependent protein kinase (PKG) functions directly as a redox sensor. The Ialpha isoform, PKGIalpha, formed an interprotein disulfide linking its two subunits in cells exposed to exogenous hydrogen peroxide. This oxidation directly activated the kinase in vitro, and in rat cells and tissues. The affinity of the kinase for substrates it phosphorylates was enhanced by disulfide formation. This oxidation-induced activation represents an alternate mechanism for regulation along with the classical activation involving nitric oxide and cGMP. This mechanism underlies cGMP-independent vasorelaxation in response to oxidants in the cardiovascular system and provides a molecular explantion for how hydrogen peroxide can operate as an endothelium-derived hyperpolarizing factor. PMID:17717153

  3. Analysis of ultra-high sensitivity configuration in chip-integrated photonic crystal microcavity bio-sensors

    SciTech Connect

    Chakravarty, Swapnajit Hosseini, Amir; Xu, Xiaochuan; Zhu, Liang; Zou, Yi; Chen, Ray T.

    2014-05-12

    We analyze the contributions of quality factor, fill fraction, and group index of chip-integrated resonance microcavity devices, to the detection limit for bulk chemical sensing and the minimum detectable biomolecule concentration in biosensing. We analyze the contributions from analyte absorbance, as well as from temperature and spectral noise. Slow light in two-dimensional photonic crystals provide opportunities for significant reduction of the detection limit below 1 × 10{sup −7} RIU (refractive index unit) which can enable highly sensitive sensors in diverse application areas. We demonstrate experimentally detected concentration of 1 fM (67 fg/ml) for the binding between biotin and avidin, the lowest reported till date.

  4. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Final ACT configuration evaluation

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The Final ACT Configuration Evaluation Task of the Integrated Application of Active Controls (IAAC) technology project within the energy efficient transport program is summarized. The Final ACT Configuration, through application of Active Controls Technology (ACT) in combination with increased wing span, exhibits significant performance improvements over the conventional baseline configuration. At the design range for these configurations, 3590 km, the block fuel used is 10% less for the Final ACT Configuration, with significant reductions in fuel usage at all operational ranges. Results of this improved fuel usage and additional system and airframe costs and the complexity required to achieve it were analyzed to determine its economic effects. For a 926 km mission, the incremental return on investment is nearly 25% at 1980 fuel prices. For longer range missions or increased fuel prices, the return is greater. The technical risks encountered in the Final ACT Configuration design and the research and development effort required to reduce these risks to levels acceptable for commercial airplane design are identified.

  5. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Wing planform study and final configuration selection

    NASA Technical Reports Server (NTRS)

    1981-01-01

    This report summarizes the Wing Planform Study Task and Final Configuration Selection of the Integrated Application of Active Controls (IAAC) Technology Project within the Energy Efficient Transport Program. Application of Active Controls Technology (ACT) in combination with increased wing span resulted in significant improvements over the Conventional Baseline Configuration (Baseline) and the Initial ACT Configuration previously established. The configurations use the same levels of technology (except for ACT), takeoff gross weight, and payload as the Baseline. The Final ACT Configuration (Model 768-107) incorporates pitch-augmented stability (which enabled an approximately 10% aft shift in cruise center of gravity and a 45% reduction in horizontal tail sizes), lateral/directional-augmented stability, an angle-of-attack limiter, and wing-load alleviation. Flutter-mode control was not beneficial for this configuration. This resulted in an 890 kg (1960 lb) reduction in airplane takeoff gross weight and a 9.8% improvement in cruise lift/drag. At the Baseline mission range (3590 km) (1938 nmi), this amounts to 10% block fuel reduction. Good takeoff performance at high-altitude airports on a hot day was also achieved. Results of this task strongly indicate that the IAAC Project should proceed with the Final ACT evaluation and begin the required control system development and testing.

  6. Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Wing planform study and final configuration selection

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The Wing Planform Study and Final Configuration Selection Task of the Integrated Application of Active Controls (IAAC) Technology Project within the Energy Efficient Transport Program is documented. Application of Active Controls Technology (ACT) in combination with increased wing span resulted in significant improvements over the Conventional Baseline Configuration (Baseline) and the Initial ACT Configuration previously established. The configurations use the same levels of technology, takeoff gross weight, and payload as the Baseline. The Final ACT Configuration (Model 768-107) incorporates pitch-augmented stability (which enabled an approximately 10% aft shift in cruise center of gravity and a 44% reduction in horizontal tail size), lateral/directional-augmented stability, an angle-of-attack limiter, and wing-load alleviation. Flutter-mode control was not beneficial for this configuration. This resulted in an 890 kg (1960 lb) reduction in airplane takeoff gross weight and a 9.8% improvement in cruise lift/drag. At the Baseline mission range (3589 km 1938 nmi), this amounts to 10% block-fuel reduction. Results of this task strongly indicate that the IAAC Project should proceed with the Final ACT evaluation, and begin the required control system development and test.

  7. Better physical activity classification using smartphone acceleration sensor.

    PubMed

    Arif, Muhammad; Bilal, Mohsin; Kattan, Ahmed; Ahamed, S Iqbal

    2014-09-01

    Obesity is becoming one of the serious problems for the health of worldwide population. Social interactions on mobile phones and computers via internet through social e-networks are one of the major causes of lack of physical activities. For the health specialist, it is important to track the record of physical activities of the obese or overweight patients to supervise weight loss control. In this study, acceleration sensor present in the smartphone is used to monitor the physical activity of the user. Physical activities including Walking, Jogging, Sitting, Standing, Walking upstairs and Walking downstairs are classified. Time domain features are extracted from the acceleration data recorded by smartphone during different physical activities. Time and space complexity of the whole framework is done by optimal feature subset selection and pruning of instances. Classification results of six physical activities are reported in this paper. Using simple time domain features, 99 % classification accuracy is achieved. Furthermore, attributes subset selection is used to remove the redundant features and to minimize the time complexity of the algorithm. A subset of 30 features produced more than 98 % classification accuracy for the six physical activities. PMID:25000988

  8. Thickness characterisation of oil spills using active microwave sensors

    NASA Astrophysics Data System (ADS)

    True, Michael; Shuchman, Robert A.; Kletzli, D. W., Jr.; Johannessen, Johnny A.; Digranes, Gunar; Berg, Sverre; Dalland, Kjell

    1994-12-01

    Oil thickness is a crucial parameter in the characterization of oil spills for environmental impact. The feasibility of using active microwave sensors to measure thickness was addressed in a series of microwave scatterometer experiments performed by Simrad Marine A/S in a wave tank at the Nansen Environmental Remote Sensing Center. The thickness of the oil layer was maintained at levels similar to the thick part of an oil spill (0.1 - 1 mm). The measurements showed the capability of active microwave sensors to measure oil spill thickness when the oil type is known. In addition to thickness characterization, the experiment studied the effects of oil viscosity, incidence angle, wind speed, wind angle, microwave frequency, and polarization. The backscatter contrast was observed to be greater for lower incidence angles which indicates that the ERS-1 viewing geometry is optimum for the detection and measurement of thick oil slicks. A thickness-dependent backscatter model was developed which included the effects of oil viscosity, composite surface effects, and oil-water reflectivities. The model viscous effects saturated when the oil thickness was greater than the viscous boundary layer thickness. This explained the observed C-VV backscatter contrast saturation for low viscosity diesel oil at thicknesses greater than 0.15 mm. The model predicted contrast saturation at greater thicknesses for the higher viscosity oils. The data showed this trend but the measurements did not extend to thicknesses which tested the model completely.

  9. Detection Thresholds of Falling Snow from Satellite-Borne Active and Passive Sensors

    NASA Technical Reports Server (NTRS)

    Skofronick-Jackson, Gail; Johnson, Benjamin T.; Munchak, S. Joseph

    2012-01-01

    surface of 0.25 g / cubic m and dendrite snowflakes be detected? If this information is known, we can focus retrieval efforts on detectable storms and concentrate advances on achievable results. Here, the focus is to determine thresholds of detection for falling snow for various snow conditions over land and lake surfaces. The results rely on simulated Weather Research Forecasting (WRF) simulations of falling snow cases since simulations provide all the information to determine the measurements from space and the ground truth. Sensitivity analyses were performed to better ascertain the relationships between multifrequency microwave and millimeter-wave sensor observations and the falling snow/underlying field of view. In addition, thresholds of detection for various sensor channel configurations, snow event system characteristics, snowflake particle assumptions, and surface types were studied. Results will be presented for active radar at Ku, Ka, and W-band and for passive radiometer channels from 10 to 183 GHz.

  10. Spatially restricted electrical activation of retinal ganglion cells in the rabbit retina by hexapolar electrode return configuration

    NASA Astrophysics Data System (ADS)

    Habib, Amgad G.; Cameron, Morven A.; Suaning, Gregg J.; Lovell, Nigel H.; Morley, John W.

    2013-06-01

    Objective. Visual prostheses currently in development aim to restore some form of vision to patients suffering from diseases such as age-related macular degeneration and retinitis pigmentosa. Most rely on electrically stimulating inner retinal cells via electrodes implanted on or near the retina, resulting in percepts of light termed ‘phosphenes’. Activation of spatially distinct populations of cells in the retina is key for pattern vision to be produced. To achieve this, the electrical stimulation must be localized, activating cells only in the direct vicinity of the stimulating electrode(s). With this goal in mind, a hexagonal return (hexapolar) configuration has been proposed as an alternative to the traditional monopolar or bipolar return configurations for electrically stimulating the retina. This study investigated the efficacy of the hexapolar configuration in localizing the activation of retinal ganglion cells (RGCs), compared to a monopolar configuration. Approach. Patch-clamp electrophysiology was used to measure the activation thresholds of RGCs in whole-mount rabbit retina to monopolar and hexapolar electrical stimulation, applied subretinally. Main results. Hexapolar activation thresholds for RGCs located outside the hex guard were found to be significantly (>2 fold) higher than those located inside the area of tissue bounded by the hex guard. The hexapolar configuration localized the activation of RGCs more effectively than its monopolar counterpart. Furthermore, no difference in hexapolar thresholds or localization was observed when using cathodic-first versus anodic-first stimulation. Significance. The hexapolar configuration may provide an improved method for electrically stimulating spatially distinct populations of cells in retinal tissue.

  11. Use of a copper electrode in alkaline medium as an amperometric sensor for sulphite in a flow-through configuration.

    PubMed

    Corbo, Dennys; Bertotti, Mauro

    2002-10-01

    A flow injection analysis (FIA) method has been developed for the determination of sulphite in beverages. The method is based on the amperometric detection (0.60 V vs Ag/AgCl (sat. NaCl)) of the analyte at a copper surface in an alkaline medium (1 M NaOH solution) with a manifold that incorporates flow extraction of sulphite as SO2 through a PTFE membrane. Under optimal experimental conditions the peak current response increases linearly with sulphite concentration over the range from 1.0 to 5.0 mM. The repeatability of the electrode response in the FIA configuration was evaluated as 4% ( n =20), the limit of detection of the method was 0.04 mM (S/N =3) and the analytical frequency was 50 h(-1). Since ethanol is also electroactive and permeates through the PTFE membrane, a strategy involving in a first step measurements of only ethanol by manipulating the pH of the donor stream was employed for wine samples. Then, both ethanol and sulphite were measured at the copper electrode at 0.40 V vs Ag/AgCl (sat. NaCl) and the sulphite concentration was determined by difference. Results for 3 different beverage samples (alcoholic and non-alcoholic) showed excellent agreement with the ones obtained by using a recommended procedure for sulphite analysis. PMID:12373388

  12. Aerodynamic Performance of an Active Flow Control Configuration Using Unstructured-Grid RANS

    NASA Technical Reports Server (NTRS)

    Joslin, Ronald D.; Viken, Sally A.

    2001-01-01

    This research is focused on assessing the value of the Reynolds-Averaged Navier-Stokes (RANS) methodology for active flow control applications. An experimental flow control database exists for a TAU0015 airfoil, which is a modification of a NACA0015 airfoil. The airfoil has discontinuities at the leading edge due to the implementation of a fluidic actuator and aft of mid chord on the upper surface. This paper documents two- and three-dimensional computational results for the baseline wing configuration (no control) with tile experimental results. The two-dimensional results suggest that the mid-chord discontinuity does not effect the aerodynamics of the wing and can be ignored for more efficient computations. The leading-edge discontinuity significantly affects tile lift and drag; hence, the integrity of the leading-edge notch discontinuity must be maintained in the computations to achieve a good match with the experimental data. The three-dimensional integrated performance results are in good agreement with the experiments inspite of some convergence and grid resolution issues.

  13. Aerodynamic Performance of an Active Flow Control Configuration Using Unstructured-Grid RANS

    NASA Technical Reports Server (NTRS)

    Joslin, Ronald D.; Viken, Sally A.

    2001-01-01

    This research is focused on assessing the value of the Reynolds-Averaged Navier-Stokes (RANS) methodology for active flow control applications. An experimental flow control database exists for a TAU0015 airfoil, which is a modification of a NACA0015 airfoil. The airfoil has discontinuities at the leading edge due to the implementation of a fluidic actuator and aft of mid chord oil the upper surface. This paper documents two- and three-dimensional computational results for the baseline wing configuration (no control) with the experimental results. The two-dimensional results suggest that the mid-chord discontinuity does not effect the aerodynamics of the wing and can be ignored for more efficient computations. The leading-edge discontinuity significantly affects the lift and drag; hence the integrity of the leading-edge notch discontinuity must be maintained in the computations to achieve a good match with the experimental data. The three-dimensional integrated performance results are in good agreement with the experiments in spite of some convergence and grid resolution issues.

  14. A 128 x 128 CMOS Active Pixel Image Sensor for Highly Integrated Imaging Systems

    NASA Technical Reports Server (NTRS)

    Mendis, Sunetra K.; Kemeny, Sabrina E.; Fossum, Eric R.

    1993-01-01

    A new CMOS-based image sensor that is intrinsically compatible with on-chip CMOS circuitry is reported. The new CMOS active pixel image sensor achieves low noise, high sensitivity, X-Y addressability, and has simple timing requirements. The image sensor was fabricated using a 2 micrometer p-well CMOS process, and consists of a 128 x 128 array of 40 micrometer x 40 micrometer pixels. The CMOS image sensor technology enables highly integrated smart image sensors, and makes the design, incorporation and fabrication of such sensors widely accessible to the integrated circuit community.

  15. Investigation of α-Thioglycoside Donors: Reactivity Studies toward Configuration-Controlled Orthogonal Activation in One-Pot Systems.

    PubMed

    Smith, Raymond; Müller-Bunz, Helge; Zhu, Xiangming

    2016-08-01

    The influence of anomeric configuration upon thioglycoside donors remains relatively unexplored. Utilizing methodology developed for the stereoselective and high-yielding synthesis of α-glycosyl thiols, a series of α-thioglycosides were synthesized, and their reactivity was compared to that of their β-counterparts. The highly selective activation observed for anomeric pairs containing a 2-O-acyl moiety and additional findings are reported. Application of a pair of "superarmed" thioglycosides to a one-pot oligosaccharide system is also described, in which selectivity is a result of configuration-based orthogonal activation. PMID:27399930

  16. Oak Ridge National Laboratory's (ORNL) Weigh-In-Motion (WIM) Configuration and Data Management Activities

    SciTech Connect

    Abercrombie, Robert K; Sheldon, Frederick T; Schlicher, Bob G

    2006-01-01

    The Oak Ridge National Laboratory (ORNL) involvement in the Weigh-in-Motion (WIM) research with both government agencies and private companies dates back to 1989. The discussion here will focus on the US Army's current need for an automated WIM system to weigh and determine the center-of-balance for military wheeled vehicles and cargo and the expanded uses of WIM data. ORNL is addressing configuration and data management issues as they relate to deployments for both military and humanitarian activities. The transition from the previous WIM Gen I to the current Gen II system illustrates a configuration and data management solution that ensures data integration, integrity, coherence and cost effectiveness. Currently, Army units use portable and fixed scales, tape measures, and calculators to determine vehicle axle, total weights and center of balance for vehicles prior to being transshipped via railcar, ship, or airlifted. Manually weighing and measuring all vehicles subject to these transshipment operations is time-consuming, labor-intensive, hazardous and is prone to human errors (e.g., misreading scales and tape measures, calculating centers of balance and wheel, axle, and vehicle weights, recording data, and transferring data from manually prepared work sheets into an electronic data base and aggravated by adverse weather conditions). Additionally, in the context of the military, the timeliness, safety, success, and effectiveness of airborne heavy-drop operations can be significantly improved by the use of an automated system to weigh and determine center of balance of vehicles while they are in motion. The lack of a standardized airlift-weighing system for joint service use also creates redundant weighing requirements at the cost of scarce resources and time. This case study can be judiciously expanded into commercial operations related to safety and enforcement. The WIM program will provide a means for the Army to automatically identify/weigh and monitor

  17. Dealing with the Effects of Sensor Displacement in Wearable Activity Recognition

    PubMed Central

    Banos, Oresti; Toth, Mate Attila; Damas, Miguel; Pomares, Hector; Rojas, Ignacio

    2014-01-01

    Most wearable activity recognition systems assume a predefined sensor deployment that remains unchanged during runtime. However, this assumption does not reflect real-life conditions. During the normal use of such systems, users may place the sensors in a position different from the predefined sensor placement. Also, sensors may move from their original location to a different one, due to a loose attachment. Activity recognition systems trained on activity patterns characteristic of a given sensor deployment may likely fail due to sensor displacements. In this work, we innovatively explore the effects of sensor displacement induced by both the intentional misplacement of sensors and self-placement by the user. The effects of sensor displacement are analyzed for standard activity recognition techniques, as well as for an alternate robust sensor fusion method proposed in a previous work. While classical recognition models show little tolerance to sensor displacement, the proposed method is proven to have notable capabilities to assimilate the changes introduced in the sensor position due to self-placement and provides considerable improvements for large misplacements. PMID:24915181

  18. Dealing with the effects of sensor displacement in wearable activity recognition.

    PubMed

    Banos, Oresti; Toth, Mate Attila; Damas, Miguel; Pomares, Hector; Rojas, Ignacio

    2014-01-01

    Most wearable activity recognition systems assume a predefined sensor deployment that remains unchanged during runtime. However, this assumption does not reflect real-life conditions. During the normal use of such systems, users may place the sensors in a position different from the predefined sensor placement. Also, sensors may move from their original location to a different one, due to a loose attachment. Activity recognition systems trained on activity patterns characteristic of a given sensor deployment may likely fail due to sensor displacements. In this work, we innovatively explore the effects of sensor displacement induced by both the intentional misplacement of sensors and self-placement by the user. The effects of sensor displacement are analyzed for standard activity recognition techniques, as well as for an alternate robust sensor fusion method proposed in a previous work. While classical recognition models show little tolerance to sensor displacement, the proposed method is proven to have notable capabilities to assimilate the changes introduced in the sensor position due to self-placement and provides considerable improvements for large misplacements. PMID:24915181

  19. Optical Breath Gas Sensor for Extravehicular Activity Application

    NASA Technical Reports Server (NTRS)

    Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Pilgrim, Jeffrey S> ; Chullen, Cinda; Falconi, Eric A.

    2012-01-01

    The function of the infrared gas transducer used during extravehicular activity (EVA) in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation Portable Life Support System (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode (LD) spectrometer based on wavelength modulation spectroscopy (WMS) is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen (O2) channel using a vertical cavity surface emitting laser (VCSEL). Both prototypes are controlled digitally with a field-programmable gate array (FPGA)/microcontroller architecture. Based on the results of the initial instrument development, further prototype development and testing of instruments leveraging the lessons learned were desired. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU. .

  20. Dynamically re-configurable CMOS imagers for an active vision system

    NASA Technical Reports Server (NTRS)

    Yang, Guang (Inventor); Pain, Bedabrata (Inventor)

    2005-01-01

    A vision system is disclosed. The system includes a pixel array, at least one multi-resolution window operation circuit, and a pixel averaging circuit. The pixel array has an array of pixels configured to receive light signals from an image having at least one tracking target. The multi-resolution window operation circuits are configured to process the image. Each of the multi-resolution window operation circuits processes each tracking target within a particular multi-resolution window. The pixel averaging circuit is configured to sample and average pixels within the particular multi-resolution window.

  1. A Bayesian approach to optimal sensor placement for structural health monitoring with application to active sensing

    NASA Astrophysics Data System (ADS)

    Flynn, Eric B.; Todd, Michael D.

    2010-05-01

    This paper introduces a novel approach for optimal sensor and/or actuator placement for structural health monitoring (SHM) applications. Starting from a general formulation of Bayes risk, we derive a global optimality criterion within a detection theory framework. The optimal configuration is then established as the one that minimizes the expected total presence of either type I or type II error during the damage detection process. While the approach is suitable for many sensing/actuation SHM processes, we focus on the example of active sensing using guided ultrasonic waves by implementing an appropriate statistical model of the wave propagation and feature extraction process. This example implements both pulse-echo and pitch-catch actuation schemes and takes into account line-of-site visibility and non-uniform damage probabilities over the monitored structure. The optimization space is searched using a genetic algorithm with a time-varying mutation rate. We provide three actuator/sensor placement test problems and discuss the optimal solutions generated by the algorithm.

  2. Retrieval of the photochemical reflectance index for assessing xanthophyll cycle activity: a comparison of near-surface optical sensors

    NASA Astrophysics Data System (ADS)

    Harris, A.; Gamon, J. A.; Pastorello, G. Z.; Wong, C. Y. S.

    2014-11-01

    systematic bias, illustrating that differences in instrument configuration (e.g. spectral response functions and band positions) can have a large impact on the PRI measurement values obtained. Despite differences in absolute PRI values, significant correlations were observed between the canopy PRI derived from both the SKR 1800 and the UniSpec instruments, and the epoxidation state of the xanthophyll cycle (r2 = 0.46 p < 0.05 and r2 = 0.76 p < 0.01, respectively). However, the dynamic range of the SKR 1800 PRI signal was often lower than more expensive instruments and thus the lower cost multispectral instrument may be less sensitive to pigment dynamics related to photosynthetic activity. Based on our findings, we make a series of recommendations for the effective use of such sensors under field conditions and advocate that sensors should be fully characterized prior to their field deployment.

  3. Special astronomical configurations, solar activity and deep degassing as a trigger of natural hazards

    NASA Astrophysics Data System (ADS)

    Natyaganov, Vladimir; Syvorotkin, Vladimir; Fedorov, Valeriy; Shopin, Sergey

    2016-04-01

    Extraordinary cases of tectonic events (strong earthquakes, volcano eruptions), mine explosions, typhoons, hurricanes, tornado outbreak sequences, ball lightnings, transient luminous events are analyzed in relation with special astronomical configurations, which are specific relative positions of the Sun, Earth, Moon and the closest planets of the Solar System (Venus, Mars and Jupiter) [1]. Usage of special astronomical coordinate systems give evidence not only of correlations but also of hidden causes-and-effect relations between the analyzed phenomena. The geocentric ecliptic latitude system is an example of such astronomical coordinate systems. It gives clear evidence of coherence between strong earthquakes and the maximal Moon declination from the plane of the ecliptic. Extraordinary cases of planet activity from the beginning of XX century till the present time are shown in the years of special astronomical configurations and abrupt increasing of solar activity. According to the empirical scheme of short-term earthquake prediction [3], geomagnetic disturbances are the triggers of earthquakes. Geomagnetic disturbances perform electromagnetic pumping (electromagnetic excitation) of the Earth's interior in the regions of intersections of seismomagnetic meridians with the plate boundaries as a result of electrothermal breakdowns in the heterogeneous medium of tectonic faults. This results in the local intensification of deep degassing [4], decreasing of shear strength of the medium that triggers earthquakes usually after 2 or 3 weeks (±2 days) after the geomagnetic disturbance. Examples of officially registered predictions of Kamchatka earthquakes with M7+ without missing events, including deep-focus earthquakes in the Okhotsk Sea since the year of 2002, are shown. It is discussed correlations and possible cause-and-effect relations between a different phenomena such as - dangerous natural hazardous events such as the record tornado outbreak sequences in the USA

  4. Magnetic force driven six degree-of-freedom active vibration isolation system using a phase compensated velocity sensor

    SciTech Connect

    Kim, Yongdae; Park, Kyihwan; Kim, Sangyoo

    2009-04-15

    A six-axis active vibration isolation system (AVIS) is developed using voice coil actuators. Point contact configuration is employed to have an easy assembly of eight voice coil actuators to an upper and a base plates. The velocity sensor, using an electromagnetic principle that is commonly used in the vibration control, is investigated since its phase lead characteristic causes an instability problem for a low frequency vibration. The performances of the AVIS are investigated in the frequency domain and finally validated by comparing with the passive isolation system using the atomic force microscope images.

  5. Adhesive disbond detection using piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Roth, William; Giurgiutiu, Victor

    2015-04-01

    The aerospace industry continues to increase the use of adhesives for structural bonding due to the increased joint efficiency (reduced weight), even distribution of the load path and decreases in stress concentrations. However, the limited techniques for verifying the strength of adhesive bonds has reduced its use on primary structures and requires an intensive inspection schedule. This paper discusses a potential structural health monitoring (SHM) technique for the detection of disbonds through the in situ inspection of adhesive joints. This is achieved through the use of piezoelectric wafer active sensors (PWAS), thin unobtrusive sensors which are permanently bonded to the aircraft structure. The detection method discussed in this study is electromechanical impedance spectroscopy (EMIS), a local vibration method. This method detects disbonds from the change in the mechanical impedance of the structure surrounding the disbond. This paper will discuss how predictive modeling can provide valuable insight into the inspection method, and provide better results than empirical methods alone. The inspection scheme was evaluated using the finite element method, and the results were verified experimentally using a large aluminum test article, and included both pristine and disbond coupons.

  6. High-sensitivity active pixel sensor with variable threshold photodetector

    NASA Astrophysics Data System (ADS)

    Jo, Sung-Hyun; Bae, Myunghan; Choi, Byoung-Soo; Lyu, Hong-Kun; Shin, Jang-Kyoo

    2015-05-01

    A novel high-sensitivity active pixel sensor (APS) with a variable threshold photodetector has been presented and for the first time, a simple SPICE model for the variable threshold photodetector is presented. Its SPICE model is in good agreement with measurements and is more simpler than the conventional model. The proposed APS has a gate/body-tied PMOSFET-type photodetector with an overlapping control gate that makes it possible to control the sensitivity of the proposed APS. It is a hybrid device composed of a metal-oxide-semiconductor field-effect transistor (MOSFET), a lateral bipolar junction transistor (BJT) and a vertical BJT. Using sufficient overlapping control gate bias to operate the MOSFET in inversion mode, the variable threshold photodetector allows for increasing the photocurrent gain by 105 at low light intensities when the control gate bias is -3 V. Thus, the proposed APS with a variable threshold photodetector has better low-light-level sensitivity than the conventional APS operating mode, and it has a variable sensitivity which is determined by the control gate bias. The proposed sensor has been fabricated by using 0.35 μm 2-poly 4-metal standard complementary MOS (CMOS) process and its characteristics have been evaluated.

  7. A Micro-Fabricated Force Sensor Using an All Thin Film Piezoelectric Active Sensor

    PubMed Central

    Lee, Junwoo; Choi, Wook; Yoo, Yong Kyoung; Hwang, Kyo Seon; Lee, Sang-Myung; Kang, Sungchul; Kim, Jinseok; Lee, Jeong Hoon

    2014-01-01

    The ability to measure pressure and force is essential in biomedical applications such as minimally invasive surgery (MIS) and palpation for detecting cancer cysts. Here, we report a force sensor for measuring a shear and normal force by combining an arrayed piezoelectric sensors layer with a precut glass top plate connected by four stress concentrating legs. We designed and fabricated a thin film piezoelectric force sensor and proposed an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source used in FET sensors. Both the linear sensor response from 3 kPa to 30 kPa and the exact signal responses from the moving direction illustrate the strong feasibility of the described thin film miniaturized piezoelectric force sensor. PMID:25429407

  8. A micro-fabricated force sensor using an all thin film piezoelectric active sensor.

    PubMed

    Lee, Junwoo; Choi, Wook; Yoo, Yong Kyoung; Hwang, Kyo Seon; Lee, Sang-Myung; Kang, Sungchul; Kim, Jinseok; Lee, Jeong Hoon

    2014-01-01

    The ability to measure pressure and force is essential in biomedical applications such as minimally invasive surgery (MIS) and palpation for detecting cancer cysts. Here, we report a force sensor for measuring a shear and normal force by combining an arrayed piezoelectric sensors layer with a precut glass top plate connected by four stress concentrating legs. We designed and fabricated a thin film piezoelectric force sensor and proposed an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source used in FET sensors. Both the linear sensor response from 3 kPa to 30 kPa and the exact signal responses from the moving direction illustrate the strong feasibility of the described thin film miniaturized piezoelectric force sensor. PMID:25429407

  9. Background Subtraction Based on Color and Depth Using Active Sensors

    PubMed Central

    Fernandez-Sanchez, Enrique J.; Diaz, Javier; Ros, Eduardo

    2013-01-01

    Depth information has been used in computer vision for a wide variety of tasks. Since active range sensors are currently available at low cost, high-quality depth maps can be used as relevant input for many applications. Background subtraction and video segmentation algorithms can be improved by fusing depth and color inputs, which are complementary and allow one to solve many classic color segmentation issues. In this paper, we describe one fusion method to combine color and depth based on an advanced color-based algorithm. This technique has been evaluated by means of a complete dataset recorded with Microsoft Kinect, which enables comparison with the original method. The proposed method outperforms the others in almost every test, showing more robustness to illumination changes, shadows, reflections and camouflage. PMID:23857259

  10. SHM of wind turbine blades using piezoelectric active-sensors

    SciTech Connect

    Park, Gyuhae; Taylor, Stuart G; Farinholt, Kevin M; Farrar, Charles R

    2010-01-01

    This paper presents a variety of structural health monitoring (SHM) techniques, based on the use of piezoelectric active-sensors, used to determine the structural integrity of wind turbine blades. Specifically, Lamb wave propagations, frequency response functions, and time series based methods are utilized to estimate the condition of wind turbine blades. For experiments, a 1m section of a 9m CX100 blade is used. Overall, these three methods yielded a sufficient damage detection capability to warrant further investigation into field deployment. A full-scale fatigue test of a CX-100 wind turbine blade is also conducted. This paper summarizes considerations needed to design such SHM systems, experimental procedures and results, and practical implementation issues that can be used as guidelines for future investigations.

  11. Gas Sensors Based on Conducting Polymers

    PubMed Central

    Bai, Hua; Shi, Gaoquan

    2007-01-01

    The gas sensors fabricated by using conducting polymers such as polyaniline (PAni), polypyrrole (PPy) and poly (3,4-ethylenedioxythiophene) (PEDOT) as the active layers have been reviewed. This review discusses the sensing mechanism and configurations of the sensors. The factors that affect the performances of the gas sensors are also addressed. The disadvantages of the sensors and a brief prospect in this research field are discussed at the end of the review.

  12. Vector Disparity Sensor with Vergence Control for Active Vision Systems

    PubMed Central

    Barranco, Francisco; Diaz, Javier; Gibaldi, Agostino; Sabatini, Silvio P.; Ros, Eduardo

    2012-01-01

    This paper presents an architecture for computing vector disparity for active vision systems as used on robotics applications. The control of the vergence angle of a binocular system allows us to efficiently explore dynamic environments, but requires a generalization of the disparity computation with respect to a static camera setup, where the disparity is strictly 1-D after the image rectification. The interaction between vision and motor control allows us to develop an active sensor that achieves high accuracy of the disparity computation around the fixation point, and fast reaction time for the vergence control. In this contribution, we address the development of a real-time architecture for vector disparity computation using an FPGA device. We implement the disparity unit and the control module for vergence, version, and tilt to determine the fixation point. In addition, two on-chip different alternatives for the vector disparity engines are discussed based on the luminance (gradient-based) and phase information of the binocular images. The multiscale versions of these engines are able to estimate the vector disparity up to 32 fps on VGA resolution images with very good accuracy as shown using benchmark sequences with known ground-truth. The performances in terms of frame-rate, resource utilization, and accuracy of the presented approaches are discussed. On the basis of these results, our study indicates that the gradient-based approach leads to the best trade-off choice for the integration with the active vision system. PMID:22438737

  13. Effects of Activation Energy to Transient Response of Semiconductor Gas Sensor

    NASA Astrophysics Data System (ADS)

    Fujimoto, Akira; Ohtani, Tatsuki

    The smell classifiable gas sensor will be desired for many applications such as gas detection alarms, process controls for food production and so on. We have tried to realize the sensor using transient responses of semiconductor gas sensor consisting of tin dioxide and pointed out that the sensor gave us different transient responses for kinds of gas. Results of model calculation showed the activation energy of chemical reaction on the sensor surface strongly depended on the transient response. We tried to estimate the activation energies by molecular orbital calculation with SnO2 Cluster. The results show that there is a liner relationship between the gradient of the transient responses and activation energies for carboxylic and alcoholic gases. Transient response will be predicted from activation energy in the same kind of gas and the smell discrimination by single semiconductor gas sensor will be realized by this relationship.

  14. A sensor and video based ontology for activity recognition in smart environments.

    PubMed

    Mitchell, D; Morrow, Philip J; Nugent, Chris D

    2014-01-01

    Activity recognition is used in a wide range of applications including healthcare and security. In a smart environment activity recognition can be used to monitor and support the activities of a user. There have been a range of methods used in activity recognition including sensor-based approaches, vision-based approaches and ontological approaches. This paper presents a novel approach to activity recognition in a smart home environment which combines sensor and video data through an ontological framework. The ontology describes the relationships and interactions between activities, the user, objects, sensors and video data. PMID:25571347

  15. Technique for Configuring an Actively Cooled Thermal Shield in a Flight System

    NASA Technical Reports Server (NTRS)

    Barkfknecht, Peter; Mustafi, Shuvo

    2011-01-01

    Broad area cooling shields are a mass-efficient alternative to conductively cooled thermal radiation shielding. The shield would actively intercept a large portion of incident thermal radiation and transport the heat away using cryogenic helium gas. The design concept consists of a conductive and conformable surface that maximizes heat transfer and formability. Broad Area Cooled (BAC) shields could potentially provide considerable mass savings for spaceflight applications by eliminating the need for a rigid thermal radiation shield for cryogen tanks. The BAC consists of a network of capillary tubes that are thermally connected to a conductive shield material. Chilled helium gas is circulated through the network and transports unwanted heat away from the cryogen tanks. The cryogenic helium gas is pumped and chilled simultaneously using a specialized pulse-tube cryocooler, which further improves the mass efficiency of the system. By reducing the thermal environment temperature from 300 to 100 K, the radiative heat load on a cryogen tank could be reduced by an order of magnitude. For a cryogenic liquid propellant scenario of oxygen and hydrogen, the boiloff of hydrogen would be significantly reduced and completely eliminated for oxygen. A major challenge in implementing this technology on large tanks is that the BAC system must be easily scalable from lab demonstrations to full-scale missions. Also, the BAC shield must be conformable to complex shapes like spheres without losing the ability to maintain constant temperature throughout. The initial design maximizes thermal conductivity between the capillary tube and the conductive radiation shielding by using thin, corrugated aluminum foil with the tube running transverse to the folds. This configuration has the added benefit of enabling the foil to stretch and contract longitudinally. This allows the BAC to conform to the complex curvature of a cryogen tank, which is key to its success. To demonstrate a BAC shield

  16. Thin n-in-p planar pixel sensors and active edge sensors for the ATLAS upgrade at HL-LHC

    NASA Astrophysics Data System (ADS)

    Terzo, S.; Macchiolo, A.; Nisius, R.; Paschen, B.

    2014-12-01

    Silicon pixel modules employing n-in-p planar sensors with an active thickness of 200 μm, produced at CiS, and 100-200 μm thin active/slim edge sensor devices, produced at VTT in Finland have been interconnected to ATLAS FE-I3 and FE-I4 read-out chips. The thin sensors are designed for high energy physics collider experiments to ensure radiation hardness at high fluences. Moreover, the active edge technology of the VTT production maximizes the sensitive region of the assembly, allowing for a reduced overlap of the modules in the pixel layer close to the beam pipe. The CiS production includes also four chip sensors according to the module geometry planned for the outer layers of the upgraded ATLAS pixel detector to be operated at the HL-LHC. The modules have been characterized using radioactive sources in the laboratory and with high precision measurements at beam tests to investigate the hit efficiency and charge collection properties at different bias voltages and particle incidence angles. The performance of the different sensor thicknesses and edge designs are compared before and after irradiation up to a fluence of 1.4 × 1016 neq/cm2.

  17. Detection Thresholds of Falling Snow from Satellite-Borne Active and Passive Sensors

    NASA Technical Reports Server (NTRS)

    Jackson, Gail

    2012-01-01

    Precipitation, including rain and snow, is a critical part of the Earth's energy and hydrology cycles. In order to collect information on the complete global precipitation cycle and to understand the energy budget in terms of precipitation, uniform global estimates of both liquid and frozen precipitation must be collected. Active observations of falling snow are somewhat easier to estimate since the radar will detect the precipitation particles and one only needs to know surface temperature to determine if it is liquid rain or snow. The challenges of estimating falling snow from passive spaceborne observations still exist though progress is being made. While these challenges are still being addressed, knowledge of their impact on expected retrieval results is an important key for understanding falling snow retrieval estimations. Important information to assess falling snow retrievals includes knowing thresholds of detection for active and passive sensors, various sensor channel configurations, snow event system characteristics, snowflake particle assumptions, and surface types. For example, can a lake effect snow system with low (2.5 km) cloud tops having an ice water content (Iwe) at the surface of 0.25 g m-3 and dendrite snowflakes be detected? If this information is known, we can focus retrieval efforts on detectable storms and concentrate advances on achievable results. Here, the focus is to determine thresholds of detection for falling snow for various snow conditions over land and lake surfaces. The analysis relies on simulated Weather Research Forecasting (WRF) simulations of falling snow cases since simulations provide all the information to determine the measurements from space and the ground truth. Results are presented for active radar at Ku, Ka, and W-band and for passive radiometer channels from 10 to 183 GHz (Skofronick-Jackson, et al. submitted to IEEE TGRS, April 2012). The notable results show: (1) the W-Band radar has detection thresholds more

  18. Integrated application of active controls (IAAC) technology to an advanced subsonic transport project. Initial ACT configuration design study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The initial ACT configuration design task of the integrated application of active controls (IAAC) technology project within the Energy Efficient Transport Program is summarized. A constrained application of active controls technology (ACT) resulted in significant improvements over a conventional baseline configuration previously established. The configuration uses the same levels of technology, takeoff gross weight, payload, and design requirements/objectives as the baseline, except for flying qualities, flutter, and ACT. The baseline wing is moved forward 1.68 m. The configuration incorporates pitch-augmented stability (which enabled an approximately 10% aft shift in cruise center of gravity and a 45% reduction in horizontal tail size), lateral/directional-augmented stability, an angle of attack limiter, wing load alleviation, and flutter mode control. This resulted in a 930 kg reduction in airplane operating empty weight and a 3.6% improvement in cruise efficiency, yielding a 13% range increase. Adjusted to the 3590 km baseline mission range, this amounts to 6% block fuel reduction and a 15.7% higher incremental return on investment, using 1978 dollars and fuel cost.

  19. 77 FR 52317 - Record of Decision for Surveillance Towed Array Sensor System Low Frequency Active Sonar

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Navy Record of Decision for Surveillance Towed Array Sensor System Low Frequency Active... Array Sensor System Low Frequency Active (SURTASS LFA) sonar systems with certain...

  20. Active Sensor Reflectance Measurements of Corn Nitrogen Status and Yield Potential

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of active crop canopy sensor reflectance measurements of in-season corn (Zea mays L.) nitrogen (N) status for directing spatially-variable N applications has been advocated to improve N use efficiency. However, first it is necessary to confirm that active sensors can reliably assess N status. Ou...

  1. Using an Active Sensor to Estimate Orchard Grass (Dactylis glomerata L.) Dry Matter Yield and Quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Remote sensing in the form of active sensors could be used to estimate forage biomass on spatial and temporal scales. The objective of this study is to use canopy reflectance measurements from an active remote sensor to compare different vegetation indices as a means of estimating final dry matter y...

  2. Using an active sensor to make in-season nitrogen recommendations for corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An active crop canopy reflectance sensor could increase N-use efficiency in corn (Zea mays L.), if temporal and spatial variability in soil N availability and plant demand are adequately accounted for with an in-season application. Our objective was to evaluate the success of using an active sensor ...

  3. Electro-active sensor, method for constructing the same; apparatus and circuitry for detection of electro-active species

    NASA Technical Reports Server (NTRS)

    Buehler, Martin (Inventor)

    2009-01-01

    An electro-active sensor includes a nonconductive platform with a first electrode set attached with a first side of a nonconductive platform. The first electrode set serves as an electrochemical cell that may be utilized to detect electro-active species in solution. A plurality of electrode sets and a variety of additional electrochemical cells and sensors may be attached with the nonconductive platform. The present invention also includes a method for constructing the aforementioned electro-active sensor. Additionally, an apparatus for detection and observation is disclosed, where the apparatus includes a sealable chamber for insertion of a portion of an electro-active sensor. The apparatus allows for monitoring and detection activities. Allowing for control of attached cells and sensors, a dual-mode circuitry is also disclosed. The dual-mode circuitry includes a switch, allowing the circuitry to be switched from a potentiostat to a galvanostat mode.

  4. Flexible and Stretchable Physical Sensor Integrated Platforms for Wearable Human-Activity Monitoringand Personal Healthcare.

    PubMed

    Trung, Tran Quang; Lee, Nae-Eung

    2016-06-01

    Flexible and stretchable physical sensors that can measure and quantify electrical signals generated by human activities are attracting a great deal of attention as they have unique characteristics, such as ultrathinness, low modulus, light weight, high flexibility, and stretchability. These flexible and stretchable physical sensors conformally attached on the surface of organs or skin can provide a new opportunity for human-activity monitoring and personal healthcare. Consequently, in recent years there has been considerable research effort devoted to the development of flexible and stretchable physical sensors to fulfill the requirements of future technology, and much progress has been achieved. Here, the most recent developments of flexible and stretchable physical sensors are described, including temperature, pressure, and strain sensors, and flexible and stretchable sensor-integrated platforms. The latest successful examples of flexible and stretchable physical sensors for the detection of temperature, pressure, and strain, as well as their novel structures, technological innovations, and challenges, are reviewed first. In the next section, recent progress regarding sensor-integrated wearable platforms is overviewed in detail. Some of the latest achievements regarding self-powered sensor-integrated wearable platform technologies are also reviewed. Further research direction and challenges are also proposed to develop a fully sensor-integrated wearable platform for monitoring human activity and personal healthcare in the near future. PMID:26840387

  5. Active vibration control using a modal-domain fiber optic sensor

    NASA Technical Reports Server (NTRS)

    Cox, David E.

    1992-01-01

    A closed-loop control experiment is described in which vibrations of a cantilevered beam are suppressed using measurements from a modal-domain fiber optic sensor. Modal-domain sensors are interference between the modes of a few-mode optical waveguide to detect strain. The fiber is bonded along the length of the beam and provides a measurement related to the strain distribution on the surface of the beam. A model for the fiber optic sensor is derived, and this model is integrated with the dynamic model of the beam. A piezoelectric actuator is also bonded to the beam and used to provide control forces. Control forces are obtained through dynamic compensation of the signal from the fiber optic sensor. The compensator is implemented with a real-time digital controller. Analytical models are verified by comparing simulations to experimental results for both open-loop and closed-loop configurations.

  6. Elaboration, activity and stability of silica-based nitroaromatic sensors.

    PubMed

    Mercier, Dimitri; Pereira, Franck; Méthivier, Christophe; Montméat, Pierre; Hairault, Lionel; Pradier, Claire-Marie

    2013-08-21

    Functionalized silica-based thin films, modified with hydrophobic groups, were synthesized and used as sensors for nitroaromatic compound (NAC) specific detection. Their performance and behavior, in terms of stability, ageing and regeneration, have been fully characterized by combining chemical characterization techniques and electron microscopy. NAC was efficiently and specifically detected using these silica-based sensors, but showed a great degradation in the presence of humidity. Moreover, the sensor sensitivity seriously decreases with storage time. Methyl- and phenyl-functionalization helped to overcome this humidity sensitivity. Surface characterization enabled us to establish a direct correlation between the appearance, and increasing amount, of adsorbed carbonyl-containing species, and sensor efficiency. This contamination, appearing after only one month, was particularly important when sensors were stored in plastic containers. Rinsing with cyclohexane enables us to recover part of the sensor performance but does not yield a complete regeneration of the sensors. This work led us to the definition of optimized elaboration and storage conditions for nitroaromatic sensors. PMID:23812282

  7. Photovoltaic power converter system with a controller configured to actively compensate load harmonics

    DOEpatents

    de Rooij, Michael Andrew; Steigerwald, Robert Louis; Delgado, Eladio Clemente

    2008-12-16

    Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.

  8. RE-DEFINING THE ROLES OF SENSORS IN OBJECTIVE PHYSICAL ACTIVITY MONITORING

    PubMed Central

    Chen, Kong Y.; Janz, Kathleen F.; Zhu, Weimo; Brychta, Robert J.

    2011-01-01

    Background As physical activity researchers are increasingly using objective portable devices, this review describes current state of the technology to assess physical activity, with a focus on specific sensors and sensor properties currently used in monitors and their strengths and weakness. Additional sensors and sensor properties desirable for activity measurement and best practices for users and developers also are discussed. Best Practices We grouped current sensors into three broad categories for objectively measuring physical activity: associated body movement, physiology, and context. Desirable sensor properties for measuring physical activity and the importance of these properties in relationship to specific applications are addressed, and the specific roles of transducers and data acquisition systems within the monitoring devices are defined. Technical advancements in sensors, microcomputer processors, memory storage, batteries, wireless communication, and digital filters have made monitors more usable for subjects (smaller, more stable, and longer running time) and for researchers (less costly, higher time resolution and memory storage, shorter download time, and user-defined data features). Future Directions Users and developers of physical activity monitors should learn about the basic properties of their sensors, such as range, accuracy, precision, while considering the data acquisition/filtering steps that may be critical to data quality and may influence the desirable measurement outcome(s). PMID:22157770

  9. Application-specific architectures of CMOS monolithic active pixel sensors

    NASA Astrophysics Data System (ADS)

    Szelezniak, Michal; Besson, Auguste; Claus, Gilles; Colledani, Claude; Degerli, Yavuz; Deptuch, Grzegorz; Deveaux, Michael; Dorokhov, Andrei; Dulinski, Wojciech; Fourches, Nicolas; Goffe, Mathieu; Grandjean, Damien; Guilloux, Fabrice; Heini, Sebastien; Himmi, Abdelkader; Hu, Christine; Jaaskelainen, Kimmo; Li, Yan; Lutz, Pierre; Orsini, Fabienne; Pellicioli, Michel; Shabetai, Alexandre; Valin, Isabelle; Winter, Marc

    2006-11-01

    Several development directions intended to adapt and optimize monolithic active pixel sensors for specific applications are presented in this work. The first example, compatible with the STAR microvertex upgrade, is based on a simple two-transistor pixel circuitry. It is suited for a long integration time, room-temperature operation and minimum power dissipation. In another approach for this application, a specific readout method is proposed, allowing optimization of the integration time independently of the full frame-readout time. The circuit consists of an in-pixel front-end voltage amplifier, with a gain on the order of five, followed by two analog memory cells. The extended version of this scheme, based on the implementation of more memory cells per pixel, is the solution considered for the outer layers of a microvertex detector at the international linear collider. For the two innermost layers, a circuit allowing fast frame scans together with on-line, on-chip data sparsification is proposed. The first results of this prototype demonstrate that the fixed pattern dispersion is reduced below a noise level of 15 e -, allowing the use of a single comparator or a low-resolution ADC per pixel column. A common element for most of the mentioned readout schemes is a low-noise, low power consumption, layout efficient in-pixel amplifier. A review of possible solutions for this element together with some experimental results is presented.

  10. Confronting Passive and Active Sensors with Non-Gaussian Statistics

    PubMed Central

    Rodríguez-Gonzálvez, Pablo.; Garcia-Gago, Jesús.; Gomez-Lahoz, Javier.; González-Aguilera, Diego.

    2014-01-01

    This paper has two motivations: firstly, to compare the Digital Surface Models (DSM) derived by passive (digital camera) and by active (terrestrial laser scanner) remote sensing systems when applied to specific architectural objects, and secondly, to test how well the Gaussian classic statistics, with its Least Squares principle, adapts to data sets where asymmetrical gross errors may appear and whether this approach should be changed for a non-parametric one. The field of geomatic technology automation is immersed in a high demanding competition in which any innovation by one of the contenders immediately challenges the opponents to propose a better improvement. Nowadays, we seem to be witnessing an improvement of terrestrial photogrammetry and its integration with computer vision to overcome the performance limitations of laser scanning methods. Through this contribution some of the issues of this “technological race” are examined from the point of view of photogrammetry. A new software is introduced and an experimental test is designed, performed and assessed to try to cast some light on this thrilling match. For the case considered in this study, the results show good agreement between both sensors, despite considerable asymmetry. This asymmetry suggests that the standard Normal parameters are not adequate to assess this type of data, especially when accuracy is of importance. In this case, standard deviation fails to provide a good estimation of the results, whereas the results obtained for the Median Absolute Deviation and for the Biweight Midvariance are more appropriate measures. PMID:25196104

  11. Active Pixel Sensor Characterization for the STAR Detector

    NASA Astrophysics Data System (ADS)

    King, Jake

    2004-10-01

    The STAR collaboration is studying matter at high temperatures and densities. If a significant improvement to the measurement of particle trajectories can be made, charmed mesons that decay away from the primary collision point could be identified. To achieve this goal, STAR is building a vertex detector consisting of a new technology Â- active pixel sensors. (APS) An APS is an implementation of standard CMOS technology in which each pixel has a photodiode directly above the epitaxial layer. Incident particles produce electron-hole pairs in the epitaxial layer, and these electrons accumulate on the photodiode. Charge from the photodiode is digitized to identify the position of the incident particle. It is important to characterize the signal to noise, readout time, and resolution on several different pixel sizes so that the vertex detector can be optimized for cost and speed. Larger pixels result in a faster data acquisition, while smaller pixels have better resolution. We will present studies of 5, 10, 20 and 30μm square pixel geometries that measure charge distribution and collection. We will also display the results of using a field emission scanning electron microscope with energies from 1 to 30 keV. This tool has the potential to probe regions of the APS integrated circuit and contribute to understanding its properties.

  12. Sensor Data Acquisition and Processing Parameters for Human Activity Classification

    PubMed Central

    Bersch, Sebastian D.; Azzi, Djamel; Khusainov, Rinat; Achumba, Ifeyinwa E.; Ries, Jana

    2014-01-01

    It is known that parameter selection for data sampling frequency and segmentation techniques (including different methods and window sizes) has an impact on the classification accuracy. For Ambient Assisted Living (AAL), no clear information to select these parameters exists, hence a wide variety and inconsistency across today's literature is observed. This paper presents the empirical investigation of different data sampling rates, segmentation techniques and segmentation window sizes and their effect on the accuracy of Activity of Daily Living (ADL) event classification and computational load for two different accelerometer sensor datasets. The study is conducted using an ANalysis Of VAriance (ANOVA) based on 32 different window sizes, three different segmentation algorithm (with and without overlap, totaling in six different parameters) and six sampling frequencies for nine common classification algorithms. The classification accuracy is based on a feature vector consisting of Root Mean Square (RMS), Mean, Signal Magnitude Area (SMA), Signal Vector Magnitude (here SMV), Energy, Entropy, FFTPeak, Standard Deviation (STD). The results are presented alongside recommendations for the parameter selection on the basis of the best performing parameter combinations that are identified by means of the corresponding Pareto curve. PMID:24599189

  13. [Monitoring winter wheat population dynamics using an active crop sensor].

    PubMed

    Wu, Jun-Hua; Yue, Shan-Chao; Hou, Peng; Meng, Qing-Feng; Cui, Zhen-Ling; Li, Fei; Chen, Xin-Ping

    2011-02-01

    Tiller density plays an important role in attaining optimum grain yield and applying topdressing N in winter wheat. However, the traditional approach based on determining tiller density is time-consuming and labor-intensive. As technology advances, remote sensing might provide an opportunity in eliminating this7 problem. In the present paper, an N rate experiment and a variety-seeding and sowing dates experiment were conducted in Quzhou County, Hebei Province in 2008/2009 to develop the models to predict the amount of winter wheat tillers. Positive linear relationships between vegetation indices and tillers were observed across growth stages (R2, 0.25-0.64 for NDVI; 0.26-0.65 for RVI). The validation results indicated that the prediction using NDVI had the higher coefficient of determination (R2, 0.54-0.64), the lower root mean square error (RMSE, 260-350 tillers m(-2)) and relative error (RE, 16.3%-23.0%) at early growth stages of winter wheat. We conclude that active GreenSeeker sensor is a promising tool for timely monitoring of winter wheat tiller density. PMID:21510421

  14. Confronting passive and active sensors with non-Gaussian statistics.

    PubMed

    Rodríguez-Gonzálvez, Pablo; Garcia-Gago, Jesús; Gomez-Lahoz, Javier; González-Aguilera, Diego

    2014-01-01

    This paper has two motivations: firstly, to compare the Digital Surface Models (DSM) derived by passive (digital camera) and by active (terrestrial laser scanner) remote sensing systems when applied to specific architectural objects, and secondly, to test how well the Gaussian classic statistics, with its Least Squares principle, adapts to data sets where asymmetrical gross errors may appear and whether this approach should be changed for a non-parametric one. The field of geomatic technology automation is immersed in a high demanding competition in which any innovation by one of the contenders immediately challenges the opponents to propose a better improvement. Nowadays, we seem to be witnessing an improvement of terrestrial photogrammetry and its integration with computer vision to overcome the performance limitations of laser scanning methods. Through this contribution some of the issues of this "technological race" are examined from the point of view of photogrammetry. A new software is introduced and an experimental test is designed, performed and assessed to try to cast some light on this thrilling match. For the case considered in this study, the results show good agreement between both sensors, despite considerable asymmetry. This asymmetry suggests that the standard Normal parameters are not adequate to assess this type of data, especially when accuracy is of importance. In this case, standard deviation fails to provide a good estimation of the results, whereas the results obtained for the Median Absolute Deviation and for the Biweight Midvariance are more appropriate measures. PMID:25196104

  15. Self-Activated Transparent All-Graphene Gas Sensor with Endurance to Humidity and Mechanical Bending.

    PubMed

    Kim, Yeon Hoo; Kim, Sang Jin; Kim, Yong-Jin; Shim, Yeong-Seok; Kim, Soo Young; Hong, Byung Hee; Jang, Ho Won

    2015-10-27

    Graphene is considered as one of leading candidates for gas sensor applications in the Internet of Things owing to its unique properties such as high sensitivity to gas adsorption, transparency, and flexibility. We present self-activated operation of all graphene gas sensors with high transparency and flexibility. The all-graphene gas sensors which consist of graphene for both sensor electrodes and active sensing area exhibit highly sensitive, selective, and reversible responses to NO2 without external heating. The sensors show reliable operation under high humidity conditions and bending strain. In addition to these remarkable device performances, the significantly facile fabrication process enlarges the potential of the all-graphene gas sensors for use in the Internet of Things and wearable electronics. PMID:26321290

  16. Structural integrated sensor and actuator systems for active flow control

    NASA Astrophysics Data System (ADS)

    Behr, Christian; Schwerter, Martin; Leester-Schädel, Monika; Wierach, Peter; Dietzel, Andreas; Sinapius, Michael

    2016-04-01

    An adaptive flow separation control system is designed and implemented as an essential part of a novel high-lift device for future aircraft. The system consists of MEMS pressure sensors to determine the flow conditions and adaptive lips to regulate the mass flow and the velocity of a wall near stream over the internally blown Coanda flap. By the oscillating lip the mass flow in the blowing slot changes dynamically, consequently the momentum exchange of the boundary layer over a high lift flap required mass flow can be reduced. These new compact and highly integrated systems provide a real-time monitoring and manipulation of the flow conditions. In this context the integration of pressure sensors into flow sensing airfoils of composite material is investigated. Mechanical and electrical properties of the integrated sensors are investigated under mechanical loads during tensile tests. The sensors contain a reference pressure chamber isolated to the ambient by a deformable membrane with integrated piezoresistors connected as a Wheatstone bridge, which outputs voltage signals depending on the ambient pressure. The composite material in which the sensors are embedded consists of 22 individual layers of unidirectional glass fiber reinforced plastic (GFRP) prepreg. The results of the experiments are used for adapting the design of the sensors and the layout of the laminate to ensure an optimized flux of force in highly loaded structures primarily for future aeronautical applications. It can be shown that the pressure sensor withstands the embedding process into fiber composites with full functional capability and predictable behavior under stress.

  17. Measuring glottal activity during voiced speech using a tuned electromagnetic resonating collar sensor

    NASA Astrophysics Data System (ADS)

    Brown, D. R., III; Keenaghan, K.; Desimini, S.

    2005-11-01

    Non-acoustic speech sensors can be employed to obtain measurements of one or more aspects of the speech production process, such as glottal activity, even in the presence of background noise. These sensors have a long history of clinical applications and have also recently been applied to the problem of denoising speech signals recorded in acoustically noisy environments (Ng et al 2000 Proc. Int. Conf. on Acoustics, Speech, and Signal Processing (ICASSP) (Istanbul, Turkey) vol 1, pp 229-32). Recently, researchers developed a new non-acoustic speech sensor based primarily on a tuned electromagnetic resonator collar (TERC) (Brown et al 2004 Meas. Sci. Technol. 15 1291). The TERC sensor measures glottal activity by sensing small changes in the dielectric properties of the glottis that result from voiced speech. This paper builds on the seminal work in Brown et al (2004). The primary contributions of this paper are (i) a description of a new single-mode TERC sensor design addressing the comfort and complexity issues of the original sensor, (ii) a complete description of new external interface systems used to obtain long-duration recordings from the TERC sensor and (iii) more extensive experimental results and analysis for the single-mode TERC sensor including spectrograms of speech containing both voiced and unvoiced speech segments in quiet and acoustically noisy environments. The experimental results demonstrate that the single-mode TERC sensor is able to detect glottal activity up to the fourth harmonic and is also insensitive to acoustic background noise.

  18. Fitness activity classification by using multiclass support vector machines on head-worn sensors.

    PubMed

    Loh, Darrell; Lee, Tien J; Zihajehzadeh, Shaghayegh; Hoskinson, Reynald; Park, Edward J

    2015-08-01

    Fitness activity classification on wearable devices can provide activity-specific information and generate more accurate performance metrics. Recently, optical head-mounted displays (OHMD) like Google Glass, Sony SmartEyeglass and Recon Jet have emerged. This paper presents a novel method to classify fitness activities using head-worn accelerometer, barometric pressure sensor and GPS, with comparisons to other common mounting locations on the body. Using multiclass SVM on head-worn sensors, we obtained an average F-score of 96.66% for classifying standing, walking, running, ascending/descending stairs and cycling. The best sensor location combinations were found to be on the ankle plus another upper body location. Using three or more sensors did not show a notable improvement over the best two-sensor combinations. PMID:26736309

  19. Electronic Motion Sensors and Heart Rate as Measures of Physical Activity in Children.

    ERIC Educational Resources Information Center

    Freedson, Patty S.

    1991-01-01

    Reviews several mechanical and electronic techniques for monitoring physical activity in children. The paper focuses on motion sensors (Large Scale Integrated Sensor and Caltrac Accelerometer) and heart rate, and it presents recommendations for establishing general guidelines for appropriate use of such monitoring devices with children. (SM)

  20. An Active Sensor Algorithm for Corn Nitrogen Recommendations Based on a Chlorophyll Meter Algorithm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In previous work we found active canopy sensor reflectance assessments of corn (Zea mays L.) N status acquired at two growth stages (V11 and V15) have the greatest potential for directing in-season N applications, but emphasized an algorithm was needed to translate sensor readings into appropriate N...

  1. Low Power Camera-on-a-Chip Using CMOS Active Pixel Sensor Technology

    NASA Technical Reports Server (NTRS)

    Fossum, E. R.

    1995-01-01

    A second generation image sensor technology has been developed at the NASA Jet Propulsion Laboratory as a result of the continuing need to miniaturize space science imaging instruments. Implemented using standard CMOS, the active pixel sensor (APS) technology permits the integration of the detector array with on-chip timing, control and signal chain electronics, including analog-to-digital conversion.

  2. Time-dependent generalized-active-space configuration-interaction approach to photoionization dynamics of atoms and molecules

    NASA Astrophysics Data System (ADS)

    Bauch, S.; Sørensen, L. K.; Madsen, L. B.

    2014-12-01

    We present a wave-function-based method to solve the time-dependent many-electron Schrödinger equation with special emphasis on strong-field ionization phenomena. The theory builds on the configuration-interaction (CI) approach supplemented by the generalized-active-space concept from quantum chemistry. The latter allows for a controllable reduction in the number of configurations in the CI expansion by imposing restrictions on the active orbital space. The method is similar to the recently formulated time-dependent restricted-active-space CI method [D. Hochstuhl and M. Bonitz, Phys. Rev. A 86, 053424 (2012), 10.1103/PhysRevA.86.053424]. We present details of our implementation and address convergence properties with respect to the active spaces and the associated account of electron correlation in both ground-state and excitation scenarios. We apply the time-dependent generalized-active-space CI theory to strong-field ionization of polar diatomic molecules and illustrate how the method allows us to uncover a strong correlation-induced shift of the preferred direction of emission of photoelectrons.

  3. Anion selective optodes: development of a fluorescent fiber optic sensor for the determination of nitrite activity

    NASA Astrophysics Data System (ADS)

    Barker, Susan L. R.; Shortreed, Michael R.; Kopelman, Raoul

    1996-12-01

    The response of state of the art anion optodes often cannot be described in a thermodynamically exact manner because the ionic strength within the membrane phase of such optodes changes during the course of a titration. Incorporating lipophilic charge sites in the anion optode membranes provides a constant ionic strength in the membrane phase, the ability to measure anion activities, and a more thermodynamically describable system. This configuration has been used to create a micrometer-sized nitrite-selective optode. Recent elucidation of the many biological roles of nitric oxide (NO) has spurred interest in sensitive and selective detection of this molecule. In biological systems NO is converted to NO2- within 30 sec and the biological concentration of NO2- is normally on the micromolar level. The optode we have prepared contains a selective vitamin B12 derivative ionophore, a fluorescent chromoionophore (ETH 2439 or ETH 5350), and lipophilic charge sites. These components are entrapped in a highly plasticized PVC matrix which is placed on the distal end of the fiber. Sensor characteristics such as limit of detection and reversibility are presented.

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

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Harries, Kent; Petrou, Michael; Bost, Joel; Quattlebaum, Josh B.

    2003-12-01

    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 electromechanical (E/M) impedance spectrum measured at the PWAS terminals. 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.

  5. Advanced activity reporting in a multi-layered unattended ground sensor network

    NASA Astrophysics Data System (ADS)

    Joslin, Todd W.

    2007-04-01

    Sensor networks are emplaced throughout the world to remotely track activity. Typically, these sensors report data such as target direction or target classification. This information is reported to a personnel-based monitor or a command and control center. The ideal sensor system will have a long mission life capability and will report information-rich actionable intelligence with high data integrity at near real-time latency. This paper discusses a multi-layered approach that includes data fusion at the Sensor Node, Sensor Field, and Command and Control Center Layer to create cohesive reports that mitigate false alarms and multiple reports of the same target while providing accurate tracking data on a situational awareness level. This approach is influenced by low-power architecture, and designed to maximize information density and reduce flooding of sensor networks.

  6. Alleviation of whirl-flutter on a joined-wing tilt-rotor aircraft configuration using active controls

    NASA Technical Reports Server (NTRS)

    Vanaken, Johannes M.

    1991-01-01

    The feasibility of using active controls to delay the onset of whirl-flutter on a joined-wing tilt rotor aircraft was investigated. The CAMRAD/JA code was used to obtain a set of linear differential equations which describe the motion of the joined-wing tilt-rotor aircraft. The hub motions due to wing/body motion is a standard input to CAMRAD/JA and were obtained from a structural dynamics model of a representative joined-wing tilt-rotor aircraft. The CAMRAD/JA output, consisting of the open-loop system matrices, and the airframe free vibration motion were input to a separate program which performed the closed-loop, active control calculations. An eigenvalue analysis was performed to determine the flutter stability of both open- and closed-loop systems. Sensor models, based upon the feedback of pure state variables and based upon hub-mounted sensors, providing physically measurable accelerations, were evaluated. It was shown that the onset of tilt-rotor whirl-flutter could be delayed from 240 to above 270 knots by feeding back vertical and span-wise accelerations, measured at the rotor hub, to the longitudinal cyclic pitch. Time response calculations at a 270-knot cruise condition showed an active cyclic pitch control level of 0.009 deg, which equates to a very acceptable 9 pound active-control force applied at the rotor hub.

  7. Inductive Displacement Sensors with a Notch Filter for an Active Magnetic Bearing System

    PubMed Central

    Chen, Seng-Chi; Le, Dinh-Kha; Nguyen, Van-Sum

    2014-01-01

    Active magnetic bearing (AMB) systems support rotating shafts without any physical contact, using electromagnetic forces. Each radial AMB uses two pairs of electromagnets at opposite sides of the rotor. This allows the rotor to float in the air gap, and the machine to operate without frictional losses. In active magnetic suspension, displacement sensors are necessary to detect the radial and axial movement of the suspended object. In a high-speed rotating machine equipped with an AMB, the rotor bending modes may be limited to the operating range. The natural frequencies of the rotor can cause instability. Thus, notch filters are a useful circuit for stabilizing the system. In addition, commercial displacement sensors are sometimes not suitable for AMB design, and cannot filter the noise caused by the natural frequencies of rotor. Hence, implementing displacement sensors based on the AMB structure is necessary to eliminate noises caused by natural frequency disturbances. The displacement sensor must be highly sensitive in the desired working range, and also exhibit a low interference noise, high stability, and low cost. In this study, we used the differential inductive sensor head and lock-in amplifier for synchronous demodulation. In addition, an active low-pass filter and a notch filter were used to eliminate disturbances, which caused by natural frequencies. As a consequence, the inductive displacement sensor achieved satisfactory linearity, high sensitivity, and disturbance elimination. This sensor can be easily produced for AMB applications. A prototype of these displacement sensors was built and tested. PMID:25029281

  8. Validation of mercury tip-switch and accelerometer activity sensors for identifying resting and active behavior in bears

    USGS Publications Warehouse

    Jasmine Ware; Rode, Karyn D.; Pagano, Anthony M.; Bromaghin, Jeffrey; Charles T Robbins; Joy Erlenbach; Shannon Jensen; Amy Cutting; Nicole Nicassio-Hiskey; Amy Hash; Owen, Megan A.; Heiko Jansen

    2015-01-01

    Activity sensors are often included in wildlife transmitters and can provide information on the behavior and activity patterns of animals remotely. However, interpreting activity-sensor data relative to animal behavior can be difficult if animals cannot be continuously observed. In this study, we examined the performance of a mercury tip-switch and a tri-axial accelerometer housed in collars to determine whether sensor data can be accurately classified as resting and active behaviors and whether data are comparable for the 2 sensor types. Five captive bears (3 polar [Ursus maritimus] and 2 brown [U. arctos horribilis]) were fitted with a collar specially designed to internally house the sensors. The bears’ behaviors were recorded, classified, and then compared with sensor readings. A separate tri-axial accelerometer that sampled continuously at a higher frequency and provided raw acceleration values from 3 axes was also mounted on the collar to compare with the lower resolution sensors. Both accelerometers more accurately identified resting and active behaviors at time intervals ranging from 1 minute to 1 hour (≥91.1% accuracy) compared with the mercury tip-switch (range = 75.5–86.3%). However, mercury tip-switch accuracy improved when sampled at longer intervals (e.g., 30–60 min). Data from the lower resolution accelerometer, but not the mercury tip-switch, accurately predicted the percentage of time spent resting during an hour. Although the number of bears available for this study was small, our results suggest that these activity sensors can remotely identify resting versus active behaviors across most time intervals. We recommend that investigators consider both study objectives and the variation in accuracy of classifying resting and active behaviors reported here when determining sampling interval.

  9. Photothermal configuration applied to the study of water vapor permeability in biodegradable films under several water activities

    NASA Astrophysics Data System (ADS)

    Lopez-Bueno, G.; Martín-Martínez, E. San; Cruz-Orea, A.; Tomas, S. A.; Tufiño, M.; Sanchez, F.

    2003-01-01

    A photothermal configuration was used to determine the water vapor permeability of biodegradable films (nixtamalized corn pericarps). The films were obtained from corn grains boiled in an alkaline solution containing water and Ca(OH)2. Samples were exposed to saturated salt solutions with relative humidity in the range 7%-97%. The water vapor diffusion coefficient was determined as a function of relative humidity. The obtained coefficients agreed with data available in the literature. It was also found that the photoacoustic amplitude shows a linear dependence on the water activity, in agreement with our theoretical model.

  10. Experimental Study on Battery-Less Sensor Network Activated by Multi-Point Wireless Energy Transmission

    NASA Astrophysics Data System (ADS)

    Maehara, Daiki; Tran, Gia Khanh; Sakaguchi, Kei; Araki, Kiyomichi

    This paper empirically validates battery-less sensor activation via wireless energy transmission to release sensors from wires and batteries. To seamlessly extend the coverage and activate sensor nodes distributed in any indoor environment, we proposed multi-point wireless energy transmission with carrier shift diversity. In this scheme, multiple transmitters are employed to compensate path-loss attenuation and orthogonal frequencies are allocated to the multiple transmitters to avoid the destructive interference that occurs when the same frequency is used by all transmitters. In our previous works, the effectiveness of the proposed scheme was validated theoretically and also empirically by using just a spectrum analyzer to measure the received power. In this paper, we develop low-energy battery-less sensor nodes whose consumed power and required received power for activation are respectively 142 uW and 400 uW. In addition, we conduct indoor experiments in which the received power and activation of battery-less sensor node are simultaneously observed by using the developed battery-less sensor node and a spectrum analyzer. The results show that the coverage of single-point and multi-point wireless energy transmission without carrier shift diversity are, respectively, 84.4% and 83.7%, while the coverage of the proposed scheme is 100%. It can be concluded that the effectiveness of the proposed scheme can be verified by our experiments using real battery-less sensor nodes.

  11. Heat-activated Plasmonic Chemical Sensors for Harsh Environments

    SciTech Connect

    Carpenter, Michael; Oh, Sang-Hyun

    2015-12-01

    A passive plasmonics based chemical sensing system to be used in harsh operating environments was investigated and developed within this program. The initial proposed technology was based on combining technologies developed at the SUNY Polytechnic Institute Colleges of Nanoscale Science and Engineering (CNSE) and at the University of Minnesota (UM). Specifically, a passive wireless technique developed at UM was to utilize a heat-activated plasmonic design to passively harvest the thermal energy from within a combustion emission stream and convert this into a narrowly focused light source. This plasmonic device was based on a bullseye design patterned into a gold film using focused ion beam methods (FIB). Critical to the design was the use of thermal stabilizing under and overlayers surrounding the gold film. These stabilizing layers were based on both atomic layer deposited films as well as metal laminate layers developed by United Technologies Aerospace Systems (UTAS). While the bullseye design was never able to be thermally stabilized for operating temperatures of 500oC or higher, an alternative energy harvesting design was developed by CNSE within this program. With this new development, plasmonic sensing results are presented where thermal energy is harvested using lithographically patterned Au nanorods, replacing the need for an external incident light source. Gas sensing results using the harvested thermal energy are in good agreement with sensing experiments, which used an external incident light source. Principal Component Analysis (PCA) was used to reduce the wavelength parameter space from 665 variables down to 4 variables with similar levels of demonstrated selectivity. The method was further improved by patterning rods which harvested energy in the near infrared, which led to a factor of 10 decrease in data acquisition times as well as demonstrated selectivity with a reduced wavelength data set. The combination of a plasmonic-based energy harvesting

  12. Structural Damage Detection with Piezoelectric Wafer Active Sensors

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor

    2011-07-01

    Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive enablers for a large class of damage detection and structural health monitoring (SHM) applications. This paper starts with a brief review of PWAS physical principles and basic modelling and continues by considering the various ways in which PWAS can be used for damage detection: (a) embedded guided-wave ultrasonics, i.e., pitch-catch, pulse-echo, phased arrays, thickness mode; (b) high-frequency modal sensing, i.e., the electro-mechanical (E/M) impedance method; (c) passive detection, i.e., acoustic emission and impact detection. An example of crack-like damage detection and localization with PWAS phased arrays on a small metallic plate is given. The modelling of PWAS detection of disbond damage in adhesive joints is achieved with the analytical transfer matrix method (TMM). The analytical methods offer the advantage of fast computation which enables parameter studies and carpet plots. A parametric study of the effect of crack size and PWAS location on disbond detection is presented. The power and energy transduction between PWAS and structure is studied analytically with a wave propagation method. Special attention is given to the mechatronics modeling of the complete transduction cycle from electrical excitation into ultrasonic acoustic waves by the piezoelectric effect, the transfer through the structure, and finally reverse piezoelectric transduction to generate the received electric signal. It is found that the combination of PWAS size and wave frequency/wavelength play an important role in identifying transduction maxima and minima that could be exploited to achieve an optimum power-efficient design. The multi-physics finite element method (MP-FEM), which permits fine discretization of damaged regions and complicated structural geometries, is used to study the generation of guided waves in a plate from an electrically excited transmitter PWAS and the capture of these waves as electric

  13. Behavior of piezoelectric wafer active sensor in various media

    NASA Astrophysics Data System (ADS)

    Kamas, Tuncay

    The dissertation addresses structural health monitoring (SHM) techniques using ultrasonic waves generated by piezoelectric wafer active sensors (PWAS) with an emphasis on the development of theoretical models of standing harmonic waves and guided waves. The focal objective of the research is to extend the theoretical study of electro-mechanical coupled PWAS as a resonator/transducer that interacts with standing and traveling waves in various media through electro-mechanical impedance spectroscopy (EMIS) method and guided wave propagation. The analytical models are developed and the coupled field finite element analysis (CF-FEA) models are simulated and verified with experiments. The dissertation is divided into two parts with respect to the developments in EMIS methods and GWP methods. In the first part, analytical and finite element models have been developed for the simulation of PWAS-EMIS in in-plane (longitudinal) and out-of-plane (thickness) mode. Temperature effects on free PWAS-EMIS are also discussed with respect to the in-plane mode. Piezoelectric material degradation on certain electrical and mechanical properties as the temperature increases is simulated by our analytical model for in-plane circular PWAS-EMIS that agrees well with the sets of experiments. Then the thickness mode PWAS-EMIS model was further developed for a PWAS resonator bonded on a plate-like structure. The latter analytical model was to determine the resonance frequencies for the normal mode expansion method through the global matrix method by considering PWAS-substrate and proof mass-PWAS-substrate models. The proof mass concept was adapted to shift the systems resonance frequencies in thickness mode. PWAS in contact with liquid medium on one of its surface has been analytically modeled and simulated the electro-mechanical response of PWAS with various liquids with different material properties such as the density and the viscosity. The second part discusses the guided wave propagation

  14. Radiation, temperature, and vacuum effects on piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Postolache, Cristian; Tudose, Mihai

    2016-03-01

    The effect of radiation, temperature, and vacuum (RTV) on piezoelectric wafer active sensors (PWASs) is discussed. This study is relevant for extending structural health monitoring (SHM) methods to space vehicle applications that are likely to be subjected to harsh environmental conditions such as extreme temperatures (hot and cold), cosmic radiation, and interplanetary vacuums. This study contains both theoretical and experimental investigations with the use of electromechanical impedance spectroscopy (EMIS). In the theoretical part, analytical models of circular PWAS resonators were used to derive analytical expressions for the temperature sensitivities of EMIS resonance and antiresonance behavior. Closed-form expressions for frequency and peak values at resonance and antiresonance were derived as functions of the coefficients of thermal expansion, {α }1, {α }2, {α }3; the Poisson ratio, ν and its sensitivity, \\partial ν /\\partial T; the relative compliance gradient (\\partial {s}11E/\\partial T)/{s}11E; and the Bessel function root, z and its sensitivity, \\partial z/\\partial T. In the experimental part, tests were conducted to subject the PWAS transducers to RTV conditions. In one set of experiments, several RTV exposure, cycles were applied with EMIS signatures recorded at the beginning and after each of the repeated cycles. In another set of experiments, PWAS transducers were subjected to various temperatures and the EMIS signatures were recorded at each temperature after stabilization. The processing of measured EMIS data from the first set of experiments revealed that the resonance and antiresonance frequencies changed by less than 1% due to RTV exposure, whereas the resonance and antiresonance amplitudes changed by around 15%. After processing an individual set of EMIS data from the second set of experiments, it was determined that the relative temperature sensitivity of the antiresonance frequency ({f}{{AR}}/{f}{{AR}}) is approximately 63.1× {10

  15. Design, synthesis, and activity of nanocellulosic protease sensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Here we contrast the molecular assembly, and biochemical utility of nanocellulosic materials prepared from cotton and wood as protease sensors. The cotton-based nanocellulosic substrates were prepared in a variety of ways to produce nanocrystals, films and aerogels, which were derivatized with eithe...

  16. A Secure Behavior Modification Sensor System for Physical Activity Improvement

    ERIC Educational Resources Information Center

    Price, Alan

    2011-01-01

    Today, advances in wireless sensor networks are making it possible to capture large amounts of information about a person and their interaction within their home environment. However, what is missing is how to ensure the security of the collected data and its use to alter human behavior for positive benefit. In this research, exploration was…

  17. Submersible microbial fuel cell sensor for monitoring microbial activity and BOD in groundwater: focusing on impact of anodic biofilm on sensor applicability.

    PubMed

    Zhang, Yifeng; Angelidaki, Irini

    2011-10-01

    A sensor, based on a submersible microbial fuel cell (SUMFC), was developed for in situ monitoring of microbial activity and biochemical oxygen demand (BOD) in groundwater. Presence or absence of a biofilm on the anode was a decisive factor for the applicability of the sensor. Fresh anode was required for application of the sensor for microbial activity measurement, while biofilm-colonized anode was needed for utilizing the sensor for BOD content measurement. The current density of SUMFC sensor equipped with a biofilm-colonized anode showed linear relationship with BOD content, to up to 250 mg/L (∼233 ± 1 mA/m(2)), with a response time of <0.67 h. This sensor could, however, not measure microbial activity, as indicated by the indifferent current produced at varying active microorganisms concentration, which was expressed as microbial adenosine-triphosphate (ATP) concentration. On the contrary, the current density (0.6 ± 0.1 to 12.4 ± 0.1 mA/m(2)) of the SUMFC sensor equipped with a fresh anode showed linear relationship, with active microorganism concentrations from 0 to 6.52 nmol-ATP/L, while no correlation between the current and BOD was observed. It was found that temperature, pH, conductivity, and inorganic solid content were significantly affecting the sensitivity of the sensor. Lastly, the sensor was tested with real contaminated groundwater, where the microbial activity and BOD content could be detected in <3.1 h. The microbial activity and BOD concentration measured by SUMFC sensor fitted well with the one measured by the standard methods, with deviations ranging from 15% to 22% and 6% to 16%, respectively. The SUMFC sensor provides a new way for in situ and quantitative monitoring contaminants content and biological activity during bioremediation process in variety of anoxic aquifers. PMID:21557205

  18. Sensor-Based Human Activity Recognition in a Multi-user Scenario

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Gu, Tao; Tao, Xianping; Lu, Jian

    Existing work on sensor-based activity recognition focuses mainly on single-user activities. However, in real life, activities are often performed by multiple users involving interactions between them. In this paper, we propose Coupled Hidden Markov Models (CHMMs) to recognize multi-user activities from sensor readings in a smart home environment. We develop a multimodal sensing platform and present a theoretical framework to recognize both single-user and multi-user activities. We conduct our trace collection done in a smart home, and evaluate our framework through experimental studies. Our experimental result shows that we achieve an average accuracy of 85.46% with CHMMs.

  19. SAN-RL: combining spreading activation networks and reinforcement learning to learn configurable behaviors

    NASA Technical Reports Server (NTRS)

    White, J.; Gaines, D. M.; Wilkes, M.; Kusumalnukool, K.; Thongchai, S.; Kawamura, K.

    2001-01-01

    This approach provides the agent with a causal structure, the spreading activation network, relating goals to the actions that can achieve those goals. This enables the agent to select actions relative to the goal priorities.

  20. Active-Pixel Image Sensor With Analog-To-Digital Converters

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R.; Mendis, Sunetra K.; Pain, Bedabrata; Nixon, Robert H.

    1995-01-01

    Proposed single-chip integrated-circuit image sensor contains 128 x 128 array of active pixel sensors at 50-micrometer pitch. Output terminals of all pixels in each given column connected to analog-to-digital (A/D) converter located at bottom of column. Pixels scanned in semiparallel fashion, one row at time; during time allocated to scanning row, outputs of all active pixel sensors in row fed to respective A/D converters. Design of chip based on complementary metal oxide semiconductor (CMOS) technology, and individual circuit elements fabricated according to 2-micrometer CMOS design rules. Active pixel sensors designed to operate at video rate of 30 frames/second, even at low light levels. A/D scheme based on first-order Sigma-Delta modulation.

  1. Using modalmetric fiber optic sensors to monitor the activity of the heart

    NASA Astrophysics Data System (ADS)

    Życzkowski, M.; Uzięblo-Zyczkowska, B.; Dziuda, L.; Różanowski, K.

    2011-03-01

    The paper presents the concept of the modalmetric fiber optic sensor system for human psychophysical activity detection. A fiber optic sensor that utilizes intensity of propagated light to monitor a patient's vital signs such as respiration cardiac activity, blood pressure and body's physical movements. The sensor, which is non-invasive, comprises an multimode fiber proximately situated to the patient so that time varying acusto-mechanical signals from the patient are coupled by the singlemode optical fiber to detector. The system can be implemented in embodiments ranging form a low cost in-home to a high end product for in hospital use. We present the laboratory test of comparing their results with the known methods like EKG. addition, the article describes the work on integrated system to human psychophysiology activity monitoring. That system including a EMFIT, microwave, fiber optic and capacitive sensors.

  2. Self-activated ultrahigh chemosensitivity of oxide thin film nanostructures for transparent sensors.

    PubMed

    Moon, Hi Gyu; Shim, Young-Soek; Kim, Do Hong; Jeong, Hu Young; Jeong, Myoungho; Jung, Joo Young; Han, Seung Min; Kim, Jong Kyu; Kim, Jin-Sang; Park, Hyung-Ho; Lee, Jong-Heun; Tuller, Harry L; Yoon, Seok-Jin; Jang, Ho Won

    2012-01-01

    One of the top design priorities for semiconductor chemical sensors is developing simple, low-cost, sensitive and reliable sensors to be built in handheld devices. However, the need to implement heating elements in sensor devices, and the resulting high power consumption, remains a major obstacle for the realization of miniaturized and integrated chemoresistive thin film sensors based on metal oxides. Here we demonstrate structurally simple but extremely efficient all oxide chemoresistive sensors with ~90% transmittance at visible wavelengths. Highly effective self-activation in anisotropically self-assembled nanocolumnar tungsten oxide thin films on glass substrate with indium-tin oxide electrodes enables ultrahigh response to nitrogen dioxide and volatile organic compounds with detection limits down to parts per trillion levels and power consumption less than 0.2 microwatts. Beyond the sensing performance, high transparency at visible wavelengths creates opportunities for their use in transparent electronic circuitry and optoelectronic devices with avenues for further functional convergence. PMID:22905319

  3. Self-activated ultrahigh chemosensitivity of oxide thin film nanostructures for transparent sensors

    PubMed Central

    Moon, Hi Gyu; Shim, Young-Soek; Kim, Do Hong; Jeong, Hu Young; Jeong, Myoungho; Jung, Joo Young; Han, Seung Min; Kim, Jong Kyu; Kim, Jin-Sang; Park, Hyung-Ho; Lee, Jong-Heun; Tuller, Harry L.; Yoon, Seok-Jin; Jang, Ho Won

    2012-01-01

    One of the top design priorities for semiconductor chemical sensors is developing simple, low-cost, sensitive and reliable sensors to be built in handheld devices. However, the need to implement heating elements in sensor devices, and the resulting high power consumption, remains a major obstacle for the realization of miniaturized and integrated chemoresistive thin film sensors based on metal oxides. Here we demonstrate structurally simple but extremely efficient all oxide chemoresistive sensors with ~90% transmittance at visible wavelengths. Highly effective self-activation in anisotropically self-assembled nanocolumnar tungsten oxide thin films on glass substrate with indium-tin oxide electrodes enables ultrahigh response to nitrogen dioxide and volatile organic compounds with detection limits down to parts per trillion levels and power consumption less than 0.2 microwatts. Beyond the sensing performance, high transparency at visible wavelengths creates opportunities for their use in transparent electronic circuitry and optoelectronic devices with avenues for further functional convergence. PMID:22905319

  4. Probing active-edge silicon sensors using a high precision telescope

    NASA Astrophysics Data System (ADS)

    Akiba, K.; Artuso, M.; van Beveren, V.; van Beuzekom, M.; Boterenbrood, H.; Buytaert, J.; Collins, P.; Dumps, R.; van der Heijden, B.; Hombach, C.; Hynds, D.; Hsu, D.; John, M.; Koffeman, E.; Leflat, A.; Li, Y.; Longstaff, I.; Morton, A.; Pérez Trigo, E.; Plackett, R.; Reid, M. M.; Rodríguez Perez, P.; Schindler, H.; Tsopelas, P.; Vázquez Sierra, C.; Wysokiński, M.

    2015-03-01

    The performance of prototype active-edge VTT sensors bump-bonded to the Timepix ASIC is presented. Non-irradiated sensors of thicknesses 100-200 μm and pixel-to-edge distances of 50 μm and 100 μm were probed with a beam of charged hadrons with sub-pixel precision using the Timepix telescope assembled at the SPS at CERN. The sensors are shown to be highly efficient up to a few micrometers from the physical edge of the sensor. The distortion of the electric field lines at the edge of the sensors is studied by reconstructing the streamlines of the electric field using two-pixel clusters. These results are supported by TCAD simulations. The reconstructed streamlines are used to study the field distortion as a function of the bias voltage and to apply corrections to the cluster positions at the edge.

  5. Microfluidic Electrochemical Sensor for On-line Monitoring of Aerosol Oxidative Activity

    PubMed Central

    Sameenoi, Yupaporn; Koehler, Kirsten; Shapiro, Jeff; Boonsong, Kanokporn; Sun, Yele; Collett, Jeffrey; Volckens, John; Henry, Charles S.

    2012-01-01

    Particulate matter (PM) air pollution has a significant impact on human morbidity and mortality; however, the mechanisms of PM-induced toxicity are poorly defined. A leading hypothesis states that airborne PM induces harm by generating reactive oxygen species (ROS) in and around human tissues, leading to oxidative stress. We report here, a system employing a microfluidic electrochemical sensor coupled directly to a Particle-into-Liquid-Sampler (PILS) system to measure aerosol oxidative activity in an on-line format. The oxidative activity measurement is based on the dithiothreitol assay (DTT assay) where after oxidized by PM, the remaining reduced DTT was analyzed by the microfluidic sensor. The sensor consists of an array of working, reference, and auxiliary electrodes fabricated in a poly(dimethylsiloxane) (PDMS)-based microfluidic device. Cobalt (II) phthalocyanine (CoPC)-modified carbon paste was used as the working electrode material allowing selective detection of reduced DTT. The electrochemical sensor was validated off-line against the traditional DTT assay using filter samples taken from urban environments and biomass burning events. After off-line characterization, the sensor was coupled to a PILS to enable on-line sampling/analysis of aerosol oxidative activity. Urban dust and industrial incinerator ash samples were aerosolized in an aerosol chamber and analyzed for their oxidative activity. The on-line sensor reported DTT consumption rates (oxidative activity) in good correlation with aerosol concentration (R2 from 0.86–.97) with a time-resolution of approximately 3 minutes. PMID:22651886

  6. Low-power sensor module for long-term activity monitoring.

    PubMed

    Leuenberger, Kaspar; Gassert, Roger

    2011-01-01

    Wearable sensor modules are a promising approach to collecting data on functional motor activities, both for repeated and long-term assessments, as well as to investigate the transfer of therapy to activities of daily living at home, but have so far either had limited sensing capabilities, or were not laid out for long-term monitoring. This paper presents ReSense, a miniature sensor unit optimized for long-term monitoring of functional activity. Inertial MEMS sensors capture accelerations along six degrees of freedom and a barometric pressure sensor serves as a precise altimeter. Data is written to an integrated memory card. The realized module measures Ø25 × 10 mm, weighs 10 g and can record continuously for 27 h at 25 Hz and over 22 h at 100 Hz. The integrated power-management system detects inactivity and extends the operating time by about a factor of two, as shown by initial 24 h recordings on five energetic healthy adults. The integrated barometric pressure sensor allowed to identify activities incorporating a change in altitude, such as going up/down stairs or riding an elevator. By taking into account data from the inertial sensors during the altitude changes, it becomes possible to distinguish between these two activities. PMID:22254785

  7. Complex Human Activity Recognition Using Smartphone and Wrist-Worn Motion Sensors

    PubMed Central

    Shoaib, Muhammad; Bosch, Stephan; Incel, Ozlem Durmaz; Scholten, Hans; Havinga, Paul J. M.

    2016-01-01

    The position of on-body motion sensors plays an important role in human activity recognition. Most often, mobile phone sensors at the trouser pocket or an equivalent position are used for this purpose. However, this position is not suitable for recognizing activities that involve hand gestures, such as smoking, eating, drinking coffee and giving a talk. To recognize such activities, wrist-worn motion sensors are used. However, these two positions are mainly used in isolation. To use richer context information, we evaluate three motion sensors (accelerometer, gyroscope and linear acceleration sensor) at both wrist and pocket positions. Using three classifiers, we show that the combination of these two positions outperforms the wrist position alone, mainly at smaller segmentation windows. Another problem is that less-repetitive activities, such as smoking, eating, giving a talk and drinking coffee, cannot be recognized easily at smaller segmentation windows unlike repetitive activities, like walking, jogging and biking. For this purpose, we evaluate the effect of seven window sizes (2–30 s) on thirteen activities and show how increasing window size affects these various activities in different ways. We also propose various optimizations to further improve the recognition of these activities. For reproducibility, we make our dataset publicly available. PMID:27023543

  8. Complex Human Activity Recognition Using Smartphone and Wrist-Worn Motion Sensors.

    PubMed

    Shoaib, Muhammad; Bosch, Stephan; Incel, Ozlem Durmaz; Scholten, Hans; Havinga, Paul J M

    2016-01-01

    The position of on-body motion sensors plays an important role in human activity recognition. Most often, mobile phone sensors at the trouser pocket or an equivalent position are used for this purpose. However, this position is not suitable for recognizing activities that involve hand gestures, such as smoking, eating, drinking coffee and giving a talk. To recognize such activities, wrist-worn motion sensors are used. However, these two positions are mainly used in isolation. To use richer context information, we evaluate three motion sensors (accelerometer, gyroscope and linear acceleration sensor) at both wrist and pocket positions. Using three classifiers, we show that the combination of these two positions outperforms the wrist position alone, mainly at smaller segmentation windows. Another problem is that less-repetitive activities, such as smoking, eating, giving a talk and drinking coffee, cannot be recognized easily at smaller segmentation windows unlike repetitive activities, like walking, jogging and biking. For this purpose, we evaluate the effect of seven window sizes (2-30 s) on thirteen activities and show how increasing window size affects these various activities in different ways. We also propose various optimizations to further improve the recognition of these activities. For reproducibility, we make our dataset publicly available. PMID:27023543

  9. Estimation of rest-activity patterns using motion sensors.

    PubMed

    Hayes, Tamara L; Riley, Thomas; Pavel, Misha; Kaye, Jeffrey A

    2010-01-01

    Disrupted sleep patterns are a significant problem in the elderly, leading to increased cognitive dysfunction and risk of nursing home placement. A cost-effective and unobtrusive way to remotely monitor changing sleep patterns over time would enable improved management of this important health problem. We have developed an algorithm to derive sleep parameters such as bed time, rise time, sleep latency, and nap time from passive infrared sensors distributed around the home. We evaluated this algorithm using 404 days of data collected in the homes of 8 elderly community-dwelling elders. Data from this algorithm were highly correlated to ground truth measures (bed mats) and were surprisingly robust to variability in sensor layout and sleep habits. PMID:21097221

  10. Toward transparent and self-activated graphene harmonic transponder sensors

    NASA Astrophysics Data System (ADS)

    Huang, Haiyu Harry; Sakhdari, Maryam; Hajizadegan, Mehdi; Shahini, Ali; Akinwande, Deji; Chen, Pai-Yen

    2016-04-01

    We propose the concept and design of a transparent, flexible, and self-powered wireless sensor comprising a graphene-based sensor/frequency-modulator circuitry and a graphene antenna. In this all-graphene device, the multilayered-graphene antenna receives the fundamental tone at C band and retransmits the frequency-modulated sensed signal (harmonic tone) at X band. The frequency orthogonality between the received/re-transmitted signals may enable high-performance sensing in severe interference/clutter background. Here, a fully passive, quad-ring frequency multiplier is proposed using graphene field-effect transistors, of which the unique ambipolar charge transports render a frequency doubling effect with conversion gain being chemically sensitive to exposed gas/molecular/chemical/infectious agents. This transparent, light-weight, and self-powered system may potentially benefit a number of wireless sensing and diagnosis applications, particularly for smart contact lenses/glasses and microscope slides that require high optical transparency.

  11. Active photonic sensor communication cable for field application of optical data and power transmission

    NASA Astrophysics Data System (ADS)

    Suthau, Eike; Rieske, Ralf; Zerna, Thomas

    2014-10-01

    Omitting electrically conducting wires for sensor communication and power supply promises protection for sensor systems and monitored structures against lightning or high voltages, prevention of explosion hazards, and reduction of susceptibility to tampering. The ability to photonically power remote systems opens up the full range of electrical sensors. Power-over-fiber is an attractive option in electromagnetically sensitive environments, particularly for longterm, maintenance-free applications. It can deliver uninterrupted power sufficient for elaborate sensors, data processing or even actuators alongside continuous high speed data communication for remote sensor application. This paper proposes an active photonic sensor communication system, which combines the advantages of optical data links in terms of immunity to electromagnetic interference (EMI), high bandwidth, hardiness against tampering or eavesdropping, and low cable weight with the robustness one has come to expect from industrial or military electrical connectors. An application specific integrated circuit (ASIC) is presented that implements a closed-loop regulation of the sensor power supply to guarantee continuous, reliable data communications while maintaining a highly efficient, adaptive sensor supply scheme. It is demonstrated that the resulting novel photonic sensor communication cable can handle sensors and actuators differing orders of magnitude with respect to power consumption. The miniaturization of the electro-optical converters and driving electronics is as important to the presented development as the energy efficiency of the detached, optically powered sensor node. For this reason, a novel photonic packaging technology based on wafer-level assembly of the laser power converters by means of passive alignment will be disclosed in this paper.

  12. Volcanic eruption source parameters from active and passive microwave sensors

    NASA Astrophysics Data System (ADS)

    Montopoli, Mario; Marzano, Frank S.; Cimini, Domenico; Mereu, Luigi

    2016-04-01

    It is well known, in the volcanology community, that precise information of the source parameters characterising an eruption are of predominant interest for the initialization of the Volcanic Transport and Dispersion Models (VTDM). Source parameters of main interest would be the top altitude of the volcanic plume, the flux of the mass ejected at the emission source, which is strictly related to the cloud top altitude, the distribution of volcanic mass concentration along the vertical column as well as the duration of the eruption and the erupted volume. Usually, the combination of a-posteriori field and numerical studies allow constraining the eruption source parameters for a given volcanic event thus making possible the forecast of ash dispersion and deposition from future volcanic eruptions. So far, remote sensors working at visible and infrared channels (cameras and radiometers) have been mainly used to detect, track and provide estimates of the concentration content and the prevailing size of the particles propagating within the ash clouds up to several thousand of kilometres far from the source as well as track back, a-posteriori, the accuracy of the VATDM outputs thus testing the initial choice made for the source parameters. Acoustic wave (infrasound) and microwave fixed scan radar (voldorad) were also used to infer source parameters. In this work we want to put our attention on the role of sensors operating at microwave wavelengths as complementary tools for the real time estimations of source parameters. Microwaves can benefit of the operability during night and day and a relatively negligible sensitivity to the presence of clouds (non precipitating weather clouds) at the cost of a limited coverage and larger spatial resolution when compared with infrared sensors. Thanks to the aforementioned advantages, the products from microwaves sensors are expected to be sensible mostly to the whole path traversed along the tephra cloud making microwaves particularly

  13. New light sources and sensors for active optical 3D inspection

    NASA Astrophysics Data System (ADS)

    Osten, Wolfgang; Jueptner, Werner P. O.

    1999-11-01

    The implementation of active processing strategies in optical 3D-inspection needs the availability of flexible hardware solutions. The system components illumination and sensor/detector are actively involved in the processing chain by a feedback loop that is controlled by the evaluation process. Therefore this article deals with new light sources and sensor which appeared recently on the market and can be applied successfully for the implementation of active processing principles. Some applications where such new components are used to implement an active measurement strategy are presented.

  14. Self healing of open circuit faults: With active re-configurability and mimicry of synaptic plasticity

    NASA Astrophysics Data System (ADS)

    Yaswant, Vaddi; Kumar, Amit; Sambandan, Sanjiv

    2016-07-01

    We discuss the self-repair of open faults in circuits using electrically conductive particles dispersed in an insulating fluid. The repair is triggered by the electric field developed across the open circuit in a current carrying interconnect and results in the formation of a bridge of particles across the gap. We illustrate and model the dynamics of the resistance of the self-healed route, Rb, in low field conditions. Furthermore, active control of Rb and active re-wiring are also demonstrated. Considering Rb to be akin to weights between nodes, the formation and re-wiring of routes and the control of Rb mimic synaptic plasticity in biological systems and open interesting possibilities for computing.

  15. Maximizing semi-active vibration isolation utilizing a magnetorheological damper with an inner bypass configuration

    NASA Astrophysics Data System (ADS)

    Bai, Xian-Xu; Wereley, Norman M.; Hu, Wei

    2015-05-01

    A single-degree-of-freedom (SDOF) semi-active vibration control system based on a magnetorheological (MR) damper with an inner bypass is investigated in this paper. The MR damper employing a pair of concentric tubes, between which the key structure, i.e., the inner bypass, is formed and MR fluids are energized, is designed to provide large dynamic range (i.e., ratio of field-on damping force to field-off damping force) and damping force range. The damping force performance of the MR damper is modeled using phenomenological model and verified by the experimental tests. In order to assess its feasibility and capability in vibration control systems, the mathematical model of a SDOF semi-active vibration control system based on the MR damper and skyhook control strategy is established. Using an MTS 244 hydraulic vibration exciter system and a dSPACE DS1103 real-time simulation system, experimental study for the SDOF semi-active vibration control system is also conducted. Simulation results are compared to experimental measurements.

  16. Active Vertical Tail Buffeting Alleviation on a Twin-Tail Fighter Configuration in a Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.

    1997-01-01

    A 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet-Affected Tails (ACROBAT) program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and other aerodynamic devices, and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at a dynamic pressure of 14 psf. By using single-input-single-output control laws at gains well below the physical limits of the control effectors, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. Stability margins indicate that a constant gain setting in the control law may be used throughout the range of angle of attack tested.

  17. Maximizing semi-active vibration isolation utilizing a magnetorheological damper with an inner bypass configuration

    SciTech Connect

    Bai, Xian-Xu; Wereley, Norman M.; Hu, Wei

    2015-05-07

    A single-degree-of-freedom (SDOF) semi-active vibration control system based on a magnetorheological (MR) damper with an inner bypass is investigated in this paper. The MR damper employing a pair of concentric tubes, between which the key structure, i.e., the inner bypass, is formed and MR fluids are energized, is designed to provide large dynamic range (i.e., ratio of field-on damping force to field-off damping force) and damping force range. The damping force performance of the MR damper is modeled using phenomenological model and verified by the experimental tests. In order to assess its feasibility and capability in vibration control systems, the mathematical model of a SDOF semi-active vibration control system based on the MR damper and skyhook control strategy is established. Using an MTS 244 hydraulic vibration exciter system and a dSPACE DS1103 real-time simulation system, experimental study for the SDOF semi-active vibration control system is also conducted. Simulation results are compared to experimental measurements.

  18. Development of a Smartphone Application to Measure Physical Activity Using Sensor-Assisted Self-Report

    PubMed Central

    Dunton, Genevieve Fridlund; Dzubur, Eldin; Kawabata, Keito; Yanez, Brenda; Bo, Bin; Intille, Stephen

    2013-01-01

    Introduction: Despite the known advantages of objective physical activity monitors (e.g., accelerometers), these devices have high rates of non-wear, which leads to missing data. Objective activity monitors are also unable to capture valuable contextual information about behavior. Adolescents recruited into physical activity surveillance and intervention studies will increasingly have smartphones, which are miniature computers with built-in motion sensors. Methods: This paper describes the design and development of a smartphone application (“app”) called Mobile Teen that combines objective and self-report assessment strategies through (1) sensor-informed context-sensitive ecological momentary assessment (CS-EMA) and (2) sensor-assisted end-of-day recall. Results: The Mobile Teen app uses the mobile phone’s built-in motion sensor to automatically detect likely bouts of phone non-wear, sedentary behavior, and physical activity. The app then uses transitions between these inferred states to trigger CS-EMA self-report surveys measuring the type, purpose, and context of activity in real-time. The end of the day recall component of the Mobile Teen app allows users to interactively review and label their own physical activity data each evening using visual cues from automatically detected major activity transitions from the phone’s built-in motion sensors. Major activity transitions are identified by the app, which cues the user to label that “chunk,” or period, of time using activity categories. Conclusion: Sensor-driven CS-EMA and end-of-day recall smartphone apps can be used to augment physical activity data collected by objective activity monitors, filling in gaps during non-wear bouts and providing additional real-time data on environmental, social, and emotional correlates of behavior. Smartphone apps such as these have potential for affordable deployment in large-scale epidemiological and intervention studies. PMID:24616888

  19. Empirical electro-optical and x-ray performance evaluation of CMOS active pixels sensor for low dose, high resolution x-ray medical imaging.

    PubMed

    Arvanitis, C D; Bohndiek, S E; Royle, G; Blue, A; Liang, H X; Clark, A; Prydderch, M; Turchetta, R; Speller, R

    2007-12-01

    Monolithic complementary metal oxide semiconductor (CMOS) active pixel sensors with high performance have gained attention in the last few years in many scientific and space applications. In order to evaluate the increasing capabilities of this technology, in particular where low dose high resolution x-ray medical imaging is required, critical electro-optical and physical x-ray performance evaluation was determined. The electro-optical performance includes read noise, full well capacity, interacting quantum efficiency, and pixels cross talk. The x-ray performance, including x-ray sensitivity, modulation transfer function, noise power spectrum, and detection quantum efficiency, has been evaluated in the mammographic energy range. The sensor is a 525 x 525 standard three transistor CMOS active pixel sensor array with more than 75% fill factor and 25 x 25 microm pixel pitch. Reading at 10 f/s, it is found that the sensor has 114 electrons total additive noise, 10(5) electrons full well capacity with shot noise limited operation, and 34% interacting quantum efficiency at 530 nm. Two different structured CsI:Tl phosphors with thickness 95 and 115 microm, respectively, have been optically coupled via a fiber optic plate to the array resulting in two different system configurations. The sensitivity of the two different system configurations was 43 and 47 electrons per x-ray incident on the sensor. The MTF at 10% of the two different system configurations was 9.5 and 9 cycles/mm with detective quantum efficiency of 0.45 and 0.48, respectively, close to zero frequency at approximately 0.44 microC/kg (1.72 mR) detector entrance exposure. The detector was quantum limited at low spatial frequencies and its performance was comparable with high resolution a: Si and charge coupled device based x-ray imagers. The detector also demonstrates almost an order of magnitude lower noise than active matrix flat panel imagers. The results suggest that CMOS active pixel sensors when coupled

  20. Empirical electro-optical and x-ray performance evaluation of CMOS active pixels sensor for low dose, high resolution x-ray medical imaging

    SciTech Connect

    Arvanitis, C. D.; Bohndiek, S. E.; Royle, G.; Blue, A.; Liang, H. X.; Clark, A.; Prydderch, M.; Turchetta, R.; Speller, R.

    2007-12-15

    Monolithic complementary metal oxide semiconductor (CMOS) active pixel sensors with high performance have gained attention in the last few years in many scientific and space applications. In order to evaluate the increasing capabilities of this technology, in particular where low dose high resolution x-ray medical imaging is required, critical electro-optical and physical x-ray performance evaluation was determined. The electro-optical performance includes read noise, full well capacity, interacting quantum efficiency, and pixels cross talk. The x-ray performance, including x-ray sensitivity, modulation transfer function, noise power spectrum, and detection quantum efficiency, has been evaluated in the mammographic energy range. The sensor is a 525x525 standard three transistor CMOS active pixel sensor array with more than 75% fill factor and 25x25 {mu}m pixel pitch. Reading at 10 f/s, it is found that the sensor has 114 electrons total additive noise, 10{sup 5} electrons full well capacity with shot noise limited operation, and 34% interacting quantum efficiency at 530 nm. Two different structured CsI:Tl phosphors with thickness 95 and 115 {mu}m, respectively, have been optically coupled via a fiber optic plate to the array resulting in two different system configurations. The sensitivity of the two different system configurations was 43 and 47 electrons per x-ray incident on the sensor. The MTF at 10% of the two different system configurations was 9.5 and 9 cycles/mm with detective quantum efficiency of 0.45 and 0.48, respectively, close to zero frequency at {approx}0.44 {mu}C/kg (1.72 mR) detector entrance exposure. The detector was quantum limited at low spatial frequencies and its performance was comparable with high resolution a:Si and charge coupled device based x-ray imagers. The detector also demonstrates almost an order of magnitude lower noise than active matrix flat panel imagers. The results suggest that CMOS active pixel sensors when coupled to

  1. Activation Biosensor for G Protein-Coupled Receptors: A FRET-Based m1 Muscarinic Activation Sensor That Regulates Gq

    PubMed Central

    Chang, Seungwoo; Ross, Elliott M.

    2012-01-01

    We describe the design, construction and validation of a fluorescence sensor to measure activation by agonist of the m1 muscarinic cholinergic receptor, a prototypical class I Gq-coupled receptor. The sensor uses an established general design in which Förster resonance energy transfer (FRET) from a circularly permuted CFP mutant to FlAsH, a selectively reactive fluorescein, is decreased 15–20% upon binding of a full agonist. Notably, the sensor displays essentially wild-type capacity to catalyze activation of Gαq, and the purified and reconstituted sensor displays appropriate regulation of affinity for agonists by Gq. We describe the strategies used to increase the agonist-driven change in FRET while simultaneously maintaining regulatory interactions with Gαq, in the context of the known structures of Class I G protein-coupled receptors. The approach should be generally applicable to other Class I receptors which include numerous important drug targets. PMID:23029161

  2. An active tactile sensor for detecting mechanical characteristics of contacted objects

    NASA Astrophysics Data System (ADS)

    Hasegawa, Y.; Shikida, M.; Sasaki, H.; Itoigawa, K.; Sato, K.

    2006-08-01

    We propose an active tactile sensor actuated by magnetic force. The tactile sensor has the advantage of being able to detect mechanical characteristics related to a tactile impression of contacted objects using a single sensor structure, much as human skin functions. It consists of a displacement-sensing element of piezoresistors formed on a silicon diaphragm, and a magnetic actuating element (a permanent magnet and a flat coil). The sensor has two modes of operation, quasi-static and vibration, and it can detect contact force, elasticity and damping of contacted objects by choosing between operation modes. We fabricated the piezoresistor sensing and magnetic actuating elements by applying the microelectromechanical systems technologies, and assembled them in a hybrid manner. The size of the sensor was 6.0 mm × 6.0 mm × 10 µm. As contact samples we used three different rubber materials with hardness values ranging from A20 to A60 in Shore A. We experimentally confirmed that both the resonance frequency and the Q-factor of the sensing element in the vibration mode changed with different samples. We were able to calculate the elastic and damping coefficients of the contacted rubber objects by analyzing the vibrational response of the diaphragm. From the results, we concluded that the active sensor can detect mechanical characteristics of contacted objects using a single sensor structure.

  3. Development and Integration of Hardware and Software for Active-Sensors in Structural Monitoring

    SciTech Connect

    Timothy G.S. Overly

    2007-10-15

    Structural Health Monitoring (SHM) promises to deliver great benefits to many industries. Primarily among them is a potential for large cost savings in maintenance of complex structures such as aircraft and civil infrastructure. However, several large obstacles remain before widespread use on structures can be accomplished. The development of three components would address many of these obstacles: a robust sensor validation procedure, a low-cost active-sensing hardware and an integrated software package for transition to field deployment. The research performed in this thesis directly addresses these three needs and facilitates the adoption of SHM on a larger scale, particularly in the realm of SHM based on piezoelectric (PZT) materials. The first obstacle addressed in this thesis is the validation of the SHM sensor network. PZT materials are used for sensor/actuators because of their unique properties, but their functionality also needs to be validated for meaningful measurements to be recorded. To allow for a robust sensor validation algorithm, the effect of temperature change on sensor diagnostics and the effect of sensor failure on SHM measurements were classified. This classification allowed for the development of a sensor diagnostic algorithm that is temperature invariant and can indicate the amount and type of sensor failure. Secondly, the absence of a suitable commercially-available active-sensing measurement node is addressed in this thesis. A node is a small compact measurement device used in a complete system. Many measurement nodes exist for conventional passive sensing, which does not actively excite the structure, but there are no measurement nodes available that both meet the active-sensing requirements and are useable outside the laboratory. This thesis develops hardware that is low-power, active-sensing and field-deployable. This node uses the impedance method for SHM measurements, and can run the sensor diagnostic algorithm also developed here

  4. Development of CMOS Active Pixel Image Sensors for Low Cost Commercial Applications

    NASA Technical Reports Server (NTRS)

    Fossum, E.; Gee, R.; Kemeny, S.; Kim, Q.; Mendis, S.; Nakamura, J.; Nixon, R.; Ortiz, M.; Pain, B.; Zhou, Z.; Ackland, B.; Dickinson, A.; Eid, E.; Inglis, D.

    1994-01-01

    This paper describes ongoing research and development of CMOS active pixel image sensors for low cost commercial applications. A number of sensor designs have been fabricated and tested in both p-well and n-well technologies. Major elements in the development of the sensor include on-chip analog signal processing circuits for the reduction of fixed pattern noise, on-chip timing and control circuits and on-chip analog-to-digital conversion (ADC). Recent results and continuing efforts in these areas will be presented.

  5. Development of CMOS Active Pixel Image Sensors for Low Cost Commercial Applications

    NASA Technical Reports Server (NTRS)

    Gee, R.; Kemeny, S.; Kim, Q.; Mendis, S.; Nakamura, J.; Nixon, R.; Ortiz, M.; Pain, B.; Staller, C.; Zhou, Z; Fossum, E.

    1994-01-01

    JPL, under sponsorship from the NASA Office of Advanced Concepts and Technology, has been developing a second-generation solid-state image sensor technology. Charge-coupled devices (CCD) are a well-established first generation image sensor technology. For both commercial and NASA applications, CCDs have numerous shortcomings. In response, the active pixel sensor (APS) technology has been under research. The major advantages of APS technology are the ability to integrate on-chip timing, control, signal-processing and analog-to-digital converter functions, reduced sensitivity to radiation effects, low power operation, and random access readout.

  6. Optical and electrical characterization of a back-thinned CMOS active pixel sensor

    NASA Astrophysics Data System (ADS)

    Blue, Andrew; Clark, A.; Houston, S.; Laing, A.; Maneuski, D.; Prydderch, M.; Turchetta, R.; O'Shea, V.

    2009-06-01

    This work will report on the first work on the characterization of a back-thinned Vanilla-a 512×512 (25 μm squared) active pixel sensor (APS). Characterization of the detectors was carried out through the analysis of photon transfer curves to yield a measurement of full well capacity, noise levels, gain constants and linearity. Spectral characterization of the sensors was also performed in the visible and UV regions. A full comparison against non-back-thinned front illuminated Vanilla sensors is included. Such measurements suggest that the Vanilla APS will be suitable for a wide range of applications, including particle physics and biomedical imaging.

  7. Comparison Study of the Photoelectrochemical Activity of Carbon Nitride with Different Photoelectrode Configurations.

    PubMed

    Lou, Shuang; Zhou, Zhixin; Shen, Yanfei; Zhan, Zongsheng; Wang, Jianhai; Liu, Songqin; Zhang, Yuanjian

    2016-08-31

    Polymeric carbon nitride (CN) has recently emerged as a novel metal-free semiconductor due to its unique electronic structure, wide availability, and promising applications in photoelectrochemical solar energy conversion. However, few works regarding CN photoelectrode optimization such as by minimization of unwanted grain boundary effects have been reported, which would greatly influence the photoelectrochemcial conversion efficiency. Herein, three general ways of preparing CN photoelectrode are presented and compared, including drop-casting of CN particles, or further blendeding with Nafion or PEDOT-PSS as the binder. In addition, the influences of CN particle sizes (0.5, 1.1, and 3.2 μm) and the film thickness (i.e., the loading amount) to the overall photoelectrochemcial activity were also evaluated in detail. As a result, when PEDOT-PSS acted as binder, CN particles with size of 0.5 μm and an optimal loading amount (2.4 mg/cm(2)) were adopted; the as-prepared CN photoelectrode had much superior photoelectrochemical activity than all other counterparts. Therefore, this study would pave the way for preparing CN photoelectrode of superior quality so as to promote CN materials to be better applied in solar fuel and sensing applications. PMID:27500462

  8. The time-dependent generalized active space configuration interaction approach to correlated ionization dynamics of diatomic molecules

    NASA Astrophysics Data System (ADS)

    Bauch, S.; Larsson, H. R.; Hinz, C.; Bonitz, M.

    2016-03-01

    In this contribution, we review the time-dependent generalized-active-space configuration interaction (TD-GAS-CI) approach to the photoionization dynamics of atoms and molecules including electron correlation effects. It is based on the configuration interaction (CI) expansion of the many-body wave function and the restriction of the determinantal space to a reduced subspace. For its numerically efficient application to photoionization, a partially-rotated basis set is used which adopts features of a localized basis with a good reference description and a grid representation for escaping wave packets. After reviewing earlier applications of the theory, we address the strong-field ionization of a one-dimensional model of the four-electron LiH molecule using TD-GAS-CI and demonstrate the importance of electron-electron correlations in the ionization yield for different orientations of the molecule w.r.t the peak of the linearly polarized laser field. A pronounced orientation-dependent variation of the yield with the pulse duration and the level of considered electron-electron correlations is observed.

  9. Evaluation and Improvement of Eddy Current Position Sensors in Magnetically Suspended Flywheel Systems

    NASA Technical Reports Server (NTRS)

    Dever, Timothy P.; Palazzolo, Alan B.; Thomas, Erwin M., III; Jansen, Ralph H.; McLallin, Kerry (Technical Monitor); Soeder, James (Technical Monitor)

    2001-01-01

    Eddy current position sensor performance is evaluated for use in a high-speed flywheel development system. The flywheel utilizes a five axis active magnetic bearing system. The eddy current sensors are used for position feedback for the bearing controller. Measured characteristics include sensitivity to multiple target materials and susceptibility to noise from the magnetic bearings and from sensor-to-sensor crosstalk. Improvements in axial sensor configuration and techniques for noise reduction are described.

  10. A multifrequency evaluation of active and passive microwave sensors for oil spill detection and assessment

    NASA Technical Reports Server (NTRS)

    Fenner, R. G.; Reid, S. C.; Solie, C. H.

    1980-01-01

    An evaluation is given of how active and passive microwave sensors can best be used in oil spill detection and assessment. Radar backscatter curves taken over oil spills are presented and their effect on synthetic aperture radar (SAR) imagery are discussed. Plots of microwave radiometric brightness variations over oil spills are presented and discussed. Recommendations as to how to select the best combination of frequency, viewing angle, and sensor type for evaluation of various aspects of oil spills are also discussed.

  11. Passive radiation detection using optically active CMOS sensors

    NASA Astrophysics Data System (ADS)

    Dosiek, Luke; Schalk, Patrick D.

    2013-05-01

    Recently, there have been a number of small-scale and hobbyist successes in employing commodity CMOS-based camera sensors for radiation detection. For example, several smartphone applications initially developed for use in areas near the Fukushima nuclear disaster are capable of detecting radiation using a cell phone camera, provided opaque tape is placed over the lens. In all current useful implementations, it is required that the sensor not be exposed to visible light. We seek to build a system that does not have this restriction. While building such a system would require sophisticated signal processing, it would nevertheless provide great benefits. In addition to fulfilling their primary function of image capture, cameras would also be able to detect unknown radiation sources even when the danger is considered to be low or non-existent. By experimentally profiling the image artifacts generated by gamma ray and β particle impacts, algorithms are developed to identify the unique features of radiation exposure, while discarding optical interaction and thermal noise effects. Preliminary results focus on achieving this goal in a laboratory setting, without regard to integration time or computational complexity. However, future work will seek to address these additional issues.

  12. Cost estimation and economical evaluation of three configurations of activated sludge process for a wastewater treatment plant (WWTP) using simulation

    NASA Astrophysics Data System (ADS)

    Jafarinejad, Shahryar

    2016-07-01

    The activated sludge (AS) process is a type of suspended growth biological wastewater treatment that is used for treating both municipal sewage and a variety of industrial wastewaters. Economical modeling and cost estimation of activated sludge processes are crucial for designing, construction, and forecasting future economical requirements of wastewater treatment plants (WWTPs). In this study, three configurations containing conventional activated sludge (CAS), extended aeration activated sludge (EAAS), and sequencing batch reactor (SBR) processes for a wastewater treatment plant in Tehran city were proposed and the total project construction, operation labor, maintenance, material, chemical, energy and amortization costs of these WWTPs were calculated and compared. Besides, effect of mixed liquor suspended solid (MLSS) amounts on costs of WWTPs was investigated. Results demonstrated that increase of MLSS decreases the total project construction, material and amortization costs of WWTPs containing EAAS and CAS. In addition, increase of this value increases the total operation, maintenance and energy costs, but does not affect chemical cost of WWTPs containing EAAS and CAS.

  13. Phosphatase activity of the voltage-sensing phosphatase, VSP, shows graded dependence on the extent of activation of the voltage sensor.

    PubMed

    Sakata, Souhei; Okamura, Yasushi

    2014-03-01

    The voltage-sensing phosphatase (VSP) consists of a voltage sensor and a cytoplasmic phosphatase region, and the movement of the voltage sensor is coupled to the phosphatase activity. However, its coupling mechanisms still remain unclear. One possible scenario is that the phosphatase is activated only when the voltage sensor is in a fully activated state. Alternatively, the enzymatic activity of single VSP proteins could be graded in distinct activated states of the voltage sensor, and partial activation of the voltage sensor could lead to partial activation of the phosphatase. To distinguish between these two possibilities, we studied a voltage sensor mutant of zebrafish VSP, where the voltage sensor moves in two steps as evidenced by analyses of charge movements of the voltage sensor and voltage clamp fluorometry. Measurements of the phosphatase activity toward phosphatidylinositol 4,5-bisphosphate revealed that both steps of voltage sensor activation are coupled to the tuning of phosphatase activities, consistent with the idea that the phosphatase activity is graded by the magnitude of the movement of the voltage sensor. PMID:24277865

  14. [HPLC enantioseparation, absolute configuration determination and anti-HIV-1 activity of (±)-F18 enantiomers].

    PubMed

    Zhang, Lei-lei; Xue, Hai; Li, Li; Lu, Xiao-fan; Chen, Zhi-wei; Lu, Gang

    2015-06-01

    Racemic (±)-F18 (10-chloromethyl-11-demethyl-12-oxo-calanolide A), an analog of nature product (+)-calanolide A, is a new anti-HIV-1 nonnucleoside reverse transcript inhibitor (NNRTI). A successful enantioseparation of (±)-F18 offering (R)-F18 and (S)-F18 was achieved by a chiral stationary phase prepared HPLC. Their absolute configurations were determined by measurement of their electronic circular dichroisms combined with modem quantum-chemical calculations. Further investigation revealed that (R)-F18 and (S)-F18 shared a similar anti-HIV activities, however, (R)-F18 was more potent than (S)-F18 against wild-type virus, K101E mutation and P225H mutation pseudoviruses. PMID:26521445

  15. Second-order perturbative corrections to the restricted active space configuration interaction with the hole and particle approach

    NASA Astrophysics Data System (ADS)

    Casanova, David

    2014-04-01

    Second-order corrections to the restricted active space configuration interaction (RASCI) with the hole and particle truncation of the excitation operator are developed. Theoretically, the computational cost of the implemented perturbative approach, abbreviated as RASCI(2), grows like its single reference counterpart in MP2. Two different forms of RASCI(2) have been explored, that is the generalized Davidson-Kapuy and the Epstein-Nesbet partitions of the Hamiltonian. The preliminary results indicate that the use of energy level shift of a few tenths of a Hartree might systematically improve the accuracy of the RASCI(2) energies. The method has been tested in the computation of the ground state energy profiles along the dissociation of the hydrogen fluoride and N2 molecules, the computation of correlation energy in the G2/97 molecular test set, and in the computation of excitation energies to low-lying states in small organic molecules.

  16. Nitric Oxide Inhibitory Activity and Absolute Configurations of Arylalkenyl α,β-Unsaturated δ/γ-Lactones from Cryptocarya concinna.

    PubMed

    Yang, Bing-Yuan; Kong, Ling-Yi; Wang, Xiao-Bing; Zhang, Yang-Mei; Li, Rui-Jun; Yang, Ming-Hua; Luo, Jian-Guang

    2016-01-22

    During an ongoing exploration of potential anti-inflammatory agents from medicinal plants, eight new arylalkenyl α,β-unsaturated δ-lactones, cryptoconcatones A-H (1-8), and two unusual arylalkenyl α,β-unsaturated γ-lactones, cryptoconcatones I and J (9 and 10), were identified from the leaves and twigs of Cryptocarya concinna. The structures of these compounds were established based on spectroscopic data (MS, 1D/2D NMR), and their absolute configurations were determined with Riguera's method, the modified Mosher's method, chemical derivatization, and the Snatzke chirality rule. Compounds 4-6 and 8-10 showed inhibitory activity toward nitric oxide (NO) production in lipopolysaccharide-induced RAW 264.7 macrophages, particularly compounds 4 and 8-10, with IC50 values of 3.2, 4.2, 3.4, and 7.5 μM, respectively. PMID:26741483

  17. Nature of red luminescence band in research-grade ZnO single crystals: A "self-activated" configurational transition

    NASA Astrophysics Data System (ADS)

    Chen, Y. N.; Xu, S. J.; Zheng, C. C.; Ning, J. Q.; Ling, F. C. C.; Anwand, W.; Brauer, G.; Skorupa, W.

    2014-07-01

    By implanting Zn+ ions into research-grade intentionally undoped ZnO single crystal for facilitating Zn interstitials (Zni) and O vacancies (VO) which is revealed by precise X-Ray diffraction rocking curves, we observe an apparent broad red luminescence band with a nearly perfect Gaussian lineshape. This red luminescence band has the zero phonon line at ˜2.4 eV and shows distinctive lattice temperature dependence which is well interpreted with the configurational coordinate model. It also shows a low "kick out" thermal energy and small thermal quenching energy. A "self-activated" optical transition between a shallow donor and the defect center of Zni-VO complex or VZnVO di-vacancies is proposed to be responsible for the red luminescence band. Accompanied with the optical transition, large lattice relaxation simultaneously occurs around the center, as indicated by the generation of multiphonons.

  18. Second-order perturbative corrections to the restricted active space configuration interaction with the hole and particle approach

    SciTech Connect

    Casanova, David

    2014-04-14

    Second-order corrections to the restricted active space configuration interaction (RASCI) with the hole and particle truncation of the excitation operator are developed. Theoretically, the computational cost of the implemented perturbative approach, abbreviated as RASCI(2), grows like its single reference counterpart in MP2. Two different forms of RASCI(2) have been explored, that is the generalized Davidson-Kapuy and the Epstein-Nesbet partitions of the Hamiltonian. The preliminary results indicate that the use of energy level shift of a few tenths of a Hartree might systematically improve the accuracy of the RASCI(2) energies. The method has been tested in the computation of the ground state energy profiles along the dissociation of the hydrogen fluoride and N{sub 2} molecules, the computation of correlation energy in the G2/97 molecular test set, and in the computation of excitation energies to low-lying states in small organic molecules.

  19. Module Configuration

    DOEpatents

    Oweis, Salah; D'Ussel, Louis; Chagnon, Guy; Zuhowski, Michael; Sack, Tim; Laucournet, Gaullume; Jackson, Edward J.

    2002-06-04

    A stand alone battery module including: (a) a mechanical configuration; (b) a thermal management configuration; (c) an electrical connection configuration; and (d) an electronics configuration. Such a module is fully interchangeable in a battery pack assembly, mechanically, from the thermal management point of view, and electrically. With the same hardware, the module can accommodate different cell sizes and, therefore, can easily have different capacities. The module structure is designed to accommodate the electronics monitoring, protection, and printed wiring assembly boards (PWAs), as well as to allow airflow through the module. A plurality of modules may easily be connected together to form a battery pack. The parts of the module are designed to facilitate their manufacture and assembly.

  20. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Inherent force activated secondary door... § 1211.13 Inherent force activated secondary door sensors. (a) Normal operation test. (1) A force... when the door applies a 15 pound (66.7 N) or less force in the down or closing direction and when...

  1. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Inherent force activated secondary door... § 1211.13 Inherent force activated secondary door sensors. (a) Normal operation test. (1) A force... when the door applies a 15 pound (66.7 N) or less force in the down or closing direction and when...

  2. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Inherent force activated secondary door... § 1211.13 Inherent force activated secondary door sensors. (a) Normal operation test. (1) A force... when the door applies a 15 pound (66.7 N) or less force in the down or closing direction and when...

  3. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Inherent force activated secondary door... § 1211.13 Inherent force activated secondary door sensors. (a) Normal operation test. (1) A force... when the door applies a 15 pound (66.7 N) or less force in the down or closing direction and when...

  4. Power budget considerations for optically activated conventional sensors and actuators

    NASA Astrophysics Data System (ADS)

    Liu, Kexing

    1991-02-01

    Optically powered conventional instrumentation with optical fiber links that combine the advantages of a familiar technology and of fiber optics is described. A number of examples are given of the development of pneumatic pressure sensors and actuators with reduced power consumption that are operated by optical power and incorporated with fiber-optic links. Their performance and power budget are discussed. They are particularly applicable to transmissions through regions having high EM interference, high EM pulses, and explosive, radiative, or corrosive hazards, such as in nuclear power plants, process plants, aircraft, or spacecraft. These low-optical-power transmission and operation characteristics will help to meet safety requirements and to reduce the system cost.

  5. Photon small-field measurements with a CMOS active pixel sensor.

    PubMed

    Spang, F Jiménez; Rosenberg, I; Hedin, E; Royle, G

    2015-06-01

    In this work the dosimetric performance of CMOS active pixel sensors for the measurement of small photon beams is presented. The detector used consisted of an array of 520  × 520 pixels on a 25 µm pitch. Dosimetric parameters measured with this sensor were compared with data collected with an ionization chamber, a film detector and GEANT4 Monte Carlo simulations. The sensor performance for beam profiles measurements was evaluated for field sizes of 0.5  × 0.5 cm(2). The high spatial resolution achieved with this sensor allowed the accurate measurement of profiles, beam penumbrae and field size under lateral electronic disequilibrium. Field size and penumbrae agreed within 5.4% and 2.2% respectively with film measurements. Agreements with ionization chambers better than 1.0% were obtained when measuring tissue-phantom ratios. Output factor measurements were in good agreement with ionization chamber and Monte Carlo simulation. The data obtained from this imaging sensor can be easily analyzed to extract dosimetric information. The results presented in this work are promising for the development and implementation of CMOS active pixel sensors for dosimetry applications. PMID:25985207

  6. Photon small-field measurements with a CMOS active pixel sensor

    NASA Astrophysics Data System (ADS)

    Jiménez Spang, F.; Rosenberg, I.; Hedin, E.; Royle, G.

    2015-06-01

    In this work the dosimetric performance of CMOS active pixel sensors for the measurement of small photon beams is presented. The detector used consisted of an array of 520  × 520 pixels on a 25 µm pitch. Dosimetric parameters measured with this sensor were compared with data collected with an ionization chamber, a film detector and GEANT4 Monte Carlo simulations. The sensor performance for beam profiles measurements was evaluated for field sizes of 0.5  × 0.5 cm2. The high spatial resolution achieved with this sensor allowed the accurate measurement of profiles, beam penumbrae and field size under lateral electronic disequilibrium. Field size and penumbrae agreed within 5.4% and 2.2% respectively with film measurements. Agreements with ionization chambers better than 1.0% were obtained when measuring tissue-phantom ratios. Output factor measurements were in good agreement with ionization chamber and Monte Carlo simulation. The data obtained from this imaging sensor can be easily analyzed to extract dosimetric information. The results presented in this work are promising for the development and implementation of CMOS active pixel sensors for dosimetry applications.

  7. Piezoelectric Active Humidity Sensors Based on Lead-Free NaNbO3 Piezoelectric Nanofibers

    PubMed Central

    Gu, Li; Zhou, Di; Cao, Jun Cheng

    2016-01-01

    The development of micro-/nano-scaled energy harvesters and the self-powered sensor system has attracted great attention due to the miniaturization and integration of the micro-device. In this work, lead-free NaNbO3 piezoelectric nanofibers with a monoclinic perovskite structure were synthesized by the far-field electrospinning method. The flexible active humidity sensors were fabricated by transferring the nanofibers from silicon to a soft polymer substrate. The sensors exhibited outstanding piezoelectric energy-harvesting performance with output voltage up to 2 V during the vibration process. The output voltage generated by the NaNbO3 sensors exhibited a negative correlation with the environmental humidity varying from 5% to 80%, where the peak-to-peak value of the output voltage generated by the sensors decreased from 0.40 to 0.07 V. The sensor also exhibited a short response time, good selectively against ethanol steam, and great temperature stability. The piezoelectric active humidity sensing property could be attributed to the increased leakage current in the NaNbO3 nanofibers, which was generated due to proton hopping among the H3O+ groups in the absorbed H2O layers under the driving force of the piezoelectric potential. PMID:27338376

  8. Piezoelectric Active Humidity Sensors Based on Lead-Free NaNbO₃ Piezoelectric Nanofibers.

    PubMed

    Gu, Li; Zhou, Di; Cao, Jun Cheng

    2016-01-01

    The development of micro-/nano-scaled energy harvesters and the self-powered sensor system has attracted great attention due to the miniaturization and integration of the micro-device. In this work, lead-free NaNbO₃ piezoelectric nanofibers with a monoclinic perovskite structure were synthesized by the far-field electrospinning method. The flexible active humidity sensors were fabricated by transferring the nanofibers from silicon to a soft polymer substrate. The sensors exhibited outstanding piezoelectric energy-harvesting performance with output voltage up to 2 V during the vibration process. The output voltage generated by the NaNbO₃ sensors exhibited a negative correlation with the environmental humidity varying from 5% to 80%, where the peak-to-peak value of the output voltage generated by the sensors decreased from 0.40 to 0.07 V. The sensor also exhibited a short response time, good selectively against ethanol steam, and great temperature stability. The piezoelectric active humidity sensing property could be attributed to the increased leakage current in the NaNbO₃ nanofibers, which was generated due to proton hopping among the H₃O⁺ groups in the absorbed H₂O layers under the driving force of the piezoelectric potential. PMID:27338376

  9. Development of radiation hard CMOS active pixel sensors for HL-LHC

    NASA Astrophysics Data System (ADS)

    Pernegger, Heinz

    2016-07-01

    New pixel detectors, based on commercial high voltage and/or high resistivity full CMOS processes, hold promise as next-generation active pixel sensors for inner and intermediate layers of the upgraded ATLAS tracker. The use of commercial CMOS processes allow cost-effective detector construction and simpler hybridisation techniques. The paper gives an overview of the results obtained on AMS-produced CMOS sensors coupled to the ATLAS Pixel FE-I4 readout chips. The SOI (silicon-on-insulator) produced sensors by XFAB hold great promise as radiation hard SOI-CMOS sensors due to their combination of partially depleted SOI transistors reducing back-gate effects. The test results include pre-/post-irradiation comparison, measurements of charge collection regions as well as test beam results.

  10. Investigations on the influence of breathing on brain activity using optical sensors

    NASA Astrophysics Data System (ADS)

    Mandavilli, Mukanda R.; Blazek, Vladimir; Schmitt, Hans J.

    1997-05-01

    In recent years investigation and understanding of the brain activity is receiving much attention. Such investigations are generally confined to few select premier research institutions where expensive and sophisticated facilities like EEG, PET, FMRI, etc. are available. Of late optical sensors are receiving much attention for biomedical applications because they are relatively simple in construction, easy to use and comparatively inexpensive. Among the biomedical optical sensors, photophlethysmographic (PPG) measuring systems have a unique position. They function as transcutaneous registration of blood volume changes in the near skin blood vessels. By recording the signals from the supply to the left and right lobes of the brain in the cerebral cortex. The oxygen content in the arterary blood flow to the brain will naturally have an important role to play in the activity of the brain. It is suggested that by positioning sensitive temperature sensors in the nostrils of a subject, one could monitor his breathing activity. By recording the outputs rom these temperature sensor for several hours, it has been noticed that the breathing activity of a subject will change from one nostril to another periodically. Besides, it has also been observed that any sudden fluctuations in the breathing pattern is accompanied by changes in the blood flow to the brain as monitored by PPG optical sensors mounted on the temples of a subject. An attempt is made to understand such events.

  11. Retrievals of Falling Snow from Satellite-borne Active and Passive Sensors

    NASA Astrophysics Data System (ADS)

    Skofronick-Jackson, Gail; Munchak, S. Joseph; Johnson, Benjamin

    2013-04-01

    Precipitation, including rain and snow, is a critical part of the Earth's energy and hydrology cycles. Precipitation impacts latent heating profiles locally while global circulation patterns distribute precipitation and energy from the equator to the poles. For the hydrological cycle, falling snow is a primary contributor in northern latitudes during the winter seasons. Falling snow is the source of snow pack accumulations that provide fresh water resources for many communities in the world. Furthermore, falling snow impacts society by causing transportation disruptions during severe snow events. In order to collect information on the complete global precipitation cycle, both liquid and frozen precipitation must be collected. The Global Precipitation Measurement (GPM) mission's Core satellite, scheduled for launch in 2014, is well designed to detect and estimate falling snow. The GPM core carries a passive radiometer with frequencies (10-183 GHz) and an active radar with Ku- and Ka-band frequencies. Combined with the 65 degree inclination of the GPM Core satellite, these instruments allow for the GPM Core to sense and retrieve information about falling snow and light rain in regions of the earth where snow is common. The GPM Core's comprehensive active and passive channel set will also allow it to serve as a unifying reference for GPM constellation radiometer satellites. Since falling snow from space is the next precipitation measurement challenge from space, information is needed to guide retrieval algorithm development for these current and future missions. This information includes thresholds of detection for various sensor channel configurations, sensitivity to macroscale snow event system characteristics, and sensitivity to microscale snowflake particle characteristics. While the work in this area will continue for many years to come, our group has made substantial progress in this area by identifying minimum detectable melted rates of ~0.5 mm/hr. Results will

  12. Retrievals of Falling Snow from Satellite-borne Active and Passive Sensors

    NASA Astrophysics Data System (ADS)

    Jackson, Gail; Munchak, S. Joseph; Johnson, Benjamin

    2014-05-01

    Precipitation, including rain and snow, is a critical part of the Earth's energy and hydrology cycles. Precipitation impacts latent heating profiles locally while global circulation patterns distribute precipitation and energy from the equator to the poles. For the hydrological cycle, falling snow is a primary contributor in northern latitudes during the winter seasons. Falling snow is the source of snow pack accumulations that provide fresh water resources for many communities in the world. Furthermore, falling snow impacts society by causing transportation disruptions during severe snow events. In order to collect information on the complete global precipitation cycle, both liquid and frozen precipitation must be collected. The Global Precipitation Measurement (GPM) mission's Core satellite, scheduled for launch in February 2014, is well designed to detect and estimate falling snow. The GPM core carries a passive radiometer with frequencies (10-183 GHz) and an active radar with Ku- and Ka-band frequencies. Combined with the 65o inclination of the GPM Core satellite, these instruments allow for the GPM Core to sense and retrieve information about falling snow and light rain in regions of the earth where snow is common. The GPM Core's comprehensive active and passive channel set will also allow it to serve as a unifying reference for GPM constellation radiometer satellites. Since falling snow from space is the next precipitation measurement challenge from space, information is needed to guide retrieval algorithm development for these current and future missions. This information includes thresholds of detection for various sensor channel configurations, sensitivity to macroscale snow event system characteristics, and sensitivity to microscale snowflake particle characteristics. While the work in this area will continue for many years to come, our group has made substantial progress in this area by identifying minimum detectable melted rates of ~0.5 mm hr-1. Results

  13. Physical Activities Monitoring Using Wearable Acceleration Sensors Attached to the Body

    PubMed Central

    2015-01-01

    Monitoring physical activities by using wireless sensors is helpful for identifying postural orientation and movements in the real-life environment. A simple and robust method based on time domain features to identify the physical activities is proposed in this paper; it uses sensors placed on the subjects’ wrist, chest and ankle. A feature set based on time domain characteristics of the acceleration signal recorded by acceleration sensors is proposed for the classification of twelve physical activities. Nine subjects performed twelve different types of physical activities, including sitting, standing, walking, running, cycling, Nordic walking, ascending stairs, descending stairs, vacuum cleaning, ironing clothes and jumping rope, and lying down (resting state). Their ages were 27.2 ± 3.3 years and their body mass index (BMI) is 25.11 ± 2.6 Kg/m2. Classification results demonstrated a high validity showing precision (a positive predictive value) and recall (sensitivity) of more than 95% for all physical activities. The overall classification accuracy for a combined feature set of three sensors is 98%. The proposed framework can be used to monitor the physical activities of a subject that can be very useful for the health professional to assess the physical activity of healthy individuals as well as patients. PMID:26203909

  14. Infrared sensor modeling for discrimination of ground-based human activity

    NASA Astrophysics Data System (ADS)

    Flug, Eric; Deaver, Dawne

    2008-04-01

    In an initial effort to better understand how motion in human activities influences sensor performance, Night Vision and Electronic Sensors Directorate (NVESD) developed a perception experiment that tests an observer's ability to identify an activity in static and dynamic scenes. Current sensor models such as NVTherm were calibrated using static imagery of military vehicles but, given the current battlefield environment, the focus has shifted more towards discriminating human activities. In these activities, motion plays an important role but this role is not well quantified by the model. This study looks at twelve hostile and non-hostile activities that may be performed on an urban roadside such as digging a hole, raking, surveillance with binoculars, and holding several weapons. The forced choice experiment presents the activities in both static and dynamic scenes so that the effect of adding motion can be evaluated. The results are analyzed and attempts are made at relating observer performance to various static and dynamic metrics and ultimately developing a calibration for the sensor model.

  15. Chemical sensor platform for non-invasive monitoring of activity and dehydration.

    PubMed

    Solovei, Dmitry; Žák, Jaromír; Majzlíková, Petra; Sedláček, Jiří; Hubálek, Jaromír

    2015-01-01

    A non-invasive solution for monitoring of the activity and dehydration of organisms is proposed in the work. For this purpose, a wireless standalone chemical sensor platform using two separate measurement techniques has been developed. The first approach for activity monitoring is based on humidity measurement. Our solution uses new humidity sensor based on a nanostructured TiO2 surface for sweat rate monitoring. The second technique is based on monitoring of potassium concentration in urine. High level of potassium concentration denotes clear occurrence of dehydration. Furthermore, a Wireless Body Area Network (WBAN) was developed for this sensor platform to manage data transfer among devices and the internet. The WBAN coordinator controls the sensor devices and collects and stores the measured data. The collected data is particular to individuals and can be shared with physicians, emergency systems or athletes' coaches. Long-time monitoring of activity and potassium concentration in urine can help maintain the appropriate water intake of elderly people or athletes and to send warning signals in the case of near dehydration. The created sensor system was calibrated and tested in laboratory and real conditions as well. The measurement results are discussed. PMID:25594591

  16. Chemical Sensor Platform for Non-Invasive Monitoring of Activity and Dehydration

    PubMed Central

    Solovei, Dmitry; Žák, Jaromír; Majzlíková, Petra; Sedláček, Jiří; Hubálek, Jaromír

    2015-01-01

    A non-invasive solution for monitoring of the activity and dehydration of organisms is proposed in the work. For this purpose, a wireless standalone chemical sensor platform using two separate measurement techniques has been developed. The first approach for activity monitoring is based on humidity measurement. Our solution uses new humidity sensor based on a nanostructured TiO2 surface for sweat rate monitoring. The second technique is based on monitoring of potassium concentration in urine. High level of potassium concentration denotes clear occurrence of dehydration. Furthermore, a Wireless Body Area Network (WBAN) was developed for this sensor platform to manage data transfer among devices and the internet. The WBAN coordinator controls the sensor devices and collects and stores the measured data. The collected data is particular to individuals and can be shared with physicians, emergency systems or athletes' coaches. Long-time monitoring of activity and potassium concentration in urine can help maintain the appropriate water intake of elderly people or athletes and to send warning signals in the case of near dehydration. The created sensor system was calibrated and tested in laboratory and real conditions as well. The measurement results are discussed. PMID:25594591

  17. An active alignment scheme for the MPTS array. [contour sensors

    NASA Technical Reports Server (NTRS)

    Iwasaki, R.

    1980-01-01

    In order to achieve and maintain required flatness of the antenna array, a rotating laser beam used for leveling applications on earth was utilized as a reference system. A photoconductive sensor with a reflective collecting surface determines the displacement and polarity of any misalignment and automatically engages a stepping motor to drive a variable-length mechanism to make the necessary corrections. Once aligned, little power is dissipated since a nulling bridge circuit that centers on the beam is used. A three-point subarray alignment arrangement is described which independently adjusts, in the three orthogonal directions, the height and tilt of subarrays within the MPTS array and readily adapts to any physical distortions of the secondary structure (such as that resulting from severe temperature extremes caused by an eclipse of the Sun). It is shown that only one rotating laser system is required since optical blockage is minimal on the array surface and that it is possible to incorporate a number of redundant laser systems for reliability without affecting the overall performance.

  18. Bioinspired active whisker sensor for robotic vibrissal tactile sensing

    NASA Astrophysics Data System (ADS)

    Ju, Feng; Ling, Shih-Fu

    2014-12-01

    A whisker transducer (WT) inspired by rat’s vibrissal tactile perception is proposed based on a transduction matrix model characterizing the electro-mechanical transduction process in both forward and backward directions. It is capable of acting as an actuator to sweep the whisker and simultaneously as a sensor to sense the force, motion, and mechanical impedance at whisker tip. Its validity is confirmed by numerical simulation using a finite element model. A prototype is then fabricated and its transduction matrix is determined by parameter identification. The calibrated WT can accurately sense mechanical impedance which is directly related to stiffness, mass and damping. Subsequent vibrissal tactile sensing of sandpaper texture reveals that the real part of mechanical impedance sensed by WT is correlated with sandpaper roughness. Texture discrimination is successfully achieved by inputting the real part to a k-means clustering algorithm. The mechanical impedance sensing ability as well as other features of the WT such as simultaneous-actuation-and-sensing makes it a good solution to robotic tactile sensing.

  19. Transparent Stretchable Self-Powered Patchable Sensor Platform with Ultrasensitive Recognition of Human Activities.

    PubMed

    Hwang, Byeong-Ung; Lee, Ju-Hyuck; Trung, Tran Quang; Roh, Eun; Kim, Do-Il; Kim, Sang-Woo; Lee, Nae-Eung

    2015-09-22

    Monitoring of human activities can provide clinically relevant information pertaining to disease diagnostics, preventive medicine, care for patients with chronic diseases, rehabilitation, and prosthetics. The recognition of strains on human skin, induced by subtle movements of muscles in the internal organs, such as the esophagus and trachea, and the motion of joints, was demonstrated using a self-powered patchable strain sensor platform, composed on multifunctional nanocomposites of low-density silver nanowires with a conductive elastomer of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate/polyurethane, with high sensitivity, stretchability, and optical transparency. The ultra-low-power consumption of the sensor, integrated with both a supercapacitor and a triboelectric nanogenerator into a single transparent stretchable platform based on the same nanocomposites, results in a self-powered monitoring system for skin strain. The capability of the sensor to recognize a wide range of strain on skin has the potential for use in new areas of invisible stretchable electronics for human monitoring. A new type of transparent, stretchable, and ultrasensitive strain sensor based on a AgNW/PEDOT:PSS/PU nanocomposite was developed. The concept of a self-powered patchable sensor system integrated with a supercapacitor and a triboelectric nanogenerator that can be used universally as an autonomous invisible sensor system was used to detect the wide range of strain on human skin. PMID:26277994

  20. Active Optical Sensors for Tree Stem Detection and Classification in Nurseries

    PubMed Central

    Garrido, Miguel; Perez-Ruiz, Manuel; Valero, Constantino; Gliever, Chris J.; Hanson, Bradley D.; Slaughter, David C.

    2014-01-01

    Active optical sensing (LIDAR and light curtain transmission) devices mounted on a mobile platform can correctly detect, localize, and classify trees. To conduct an evaluation and comparison of the different sensors, an optical encoder wheel was used for vehicle odometry and provided a measurement of the linear displacement of the prototype vehicle along a row of tree seedlings as a reference for each recorded sensor measurement. The field trials were conducted in a juvenile tree nursery with one-year-old grafted almond trees at Sierra Gold Nurseries, Yuba City, CA, United States. Through these tests and subsequent data processing, each sensor was individually evaluated to characterize their reliability, as well as their advantages and disadvantages for the proposed task. Test results indicated that 95.7% and 99.48% of the trees were successfully detected with the LIDAR and light curtain sensors, respectively. LIDAR correctly classified, between alive or dead tree states at a 93.75% success rate compared to 94.16% for the light curtain sensor. These results can help system designers select the most reliable sensor for the accurate detection and localization of each tree in a nursery, which might allow labor-intensive tasks, such as weeding, to be automated without damaging crops. PMID:24949638

  1. Active optical sensors for tree stem detection and classification in nurseries.

    PubMed

    Garrido, Miguel; Perez-Ruiz, Manuel; Valero, Constantino; Gliever, Chris J; Hanson, Bradley D; Slaughter, David C

    2014-01-01

    Active optical sensing (LIDAR and light curtain transmission) devices mounted on a mobile platform can correctly detect, localize, and classify trees. To conduct an evaluation and comparison of the different sensors, an optical encoder wheel was used for vehicle odometry and provided a measurement of the linear displacement of the prototype vehicle along a row of tree seedlings as a reference for each recorded sensor measurement. The field trials were conducted in a juvenile tree nursery with one-year-old grafted almond trees at Sierra Gold Nurseries, Yuba City, CA, United States. Through these tests and subsequent data processing, each sensor was individually evaluated to characterize their reliability, as well as their advantages and disadvantages for the proposed task. Test results indicated that 95.7% and 99.48% of the trees were successfully detected with the LIDAR and light curtain sensors, respectively. LIDAR correctly classified, between alive or dead tree states at a 93.75% success rate compared to 94.16% for the light curtain sensor. These results can help system designers select the most reliable sensor for the accurate detection and localization of each tree in a nursery, which might allow labor-intensive tasks, such as weeding, to be automated without damaging crops. PMID:24949638

  2. Recognizing Complex Upper Extremity Activities Using Body Worn Sensors

    PubMed Central

    Lemmens, Ryanne J. M.; Janssen-Potten, Yvonne J. M.; Timmermans, Annick A. A.; Smeets, Rob J. E. M.; Seelen, Henk A. M.

    2015-01-01

    To evaluate arm-hand therapies for neurological patients it is important to be able to assess actual arm-hand performance objectively. Because instruments that measure the actual quality and quantity of specific activities in daily life are lacking, a new measure needs to be developed. The aims of this study are to a) elucidate the techniques used to identify upper extremity activities, b) provide a proof-of-principle of this method using a set of activities tested in a healthy adult and in a stroke patient, and c) provide an example of the method’s applicability in daily life based on readings taken from a healthy adult. Multiple devices, each of which contains a tri-axial accelerometer, a tri-axial gyroscope and a tri-axial magnetometer were attached to the dominant hand, wrist, upper arm and chest of 30 healthy participants and one stroke patient, who all performed the tasks ‘drinking’, ‘eating’ and ‘brushing hair’ in a standardized environment. To establish proof-of-principle, a prolonged daily life recording of 1 participant was used to identify the task ‘drinking’. The activities were identified using multi-array signal feature extraction and pattern recognition algorithms and 2D-convolution. The activities ‘drinking’, ‘eating’ and ‘brushing hair’ were unambiguously recognized in a sequence of recordings of multiple standardized daily activities in a healthy participant and in a stroke patient. It was also possible to identify a specific activity in a daily life recording. The long term aim is to use this method to a) identify arm-hand activities that someone performs during daily life, b) determine the quantity of activity execution, i.e. amount of use, and c) determine the quality of arm-hand skill performance. PMID:25734641

  3. ZigBee-based wireless multi-sensor system for physical activity assessment.

    PubMed

    Mo, Lingfei; Liu, Shaopeng; Gao, Robert X; John, Dinesh; Staudenmayer, John; Freedson, Patty

    2011-01-01

    Physical activity (PA) is important for assessing human exposure to the environment. This paper presents a ZigBee-based Wireless wearable multi-sensor Integrated Measurement System (WIMS) for in-situ PA measurement. Two accelerometers, a piezoelectric displacement sensor, and an ultraviolet (UV) sensor have been used for the physical activity assessment. Detailed analysis was performed for the hardware design and embedded program control, enabling efficient data sampling and transmission, compact design, and extended battery life to meet requirements for PA assessment under free-living conditions. Preliminary testing of the WIMS has demonstrated the functionality of the design, while performance comparison of the WIMS with a wired version on an electromagnetic shaker has demonstrated the signal validity. PMID:22254443

  4. A Wireless Seismoacoustic Sensor Network for Monitoring Activity at Volcano Reventador, Ecuador

    NASA Astrophysics Data System (ADS)

    Welsh, M.; Werner-Allen, G.; Lorincz, K.; Marcillo, O.; Ruiz, M.; Johnson, J.; Lees, J. M.

    2005-12-01

    We developed a wireless sensor network for monitoring seismoacoustic activity at Volcano Reventador, Ecuador. Wireless sensor networks are a new technology and our group is among the first to apply them to monitoring volcanoes. The small size, low power, and wireless communication capabilities can greatly simplify deployments of large sensor arrays. The network consisted of 16 wireless sensor nodes, each outfitted with an 8 MHz CPU (TI MSP430) and a 2.4 GHz IEEE 802.15.4 radio (Chipcon CC2420) with data rates up to 80 Kbps. Each node acquired acoustic and seismic data at 24-bit resolution, with a microphone and either a single-axis geophone or triaxial short-period seismometer. Each node is powered by two D-cell batteries with a lifetime of about 1 week, and measures 18 x 10 x 8 cm. Nodes were distributed radially from the vent over a 3 km aperture. Control and data messages are relayed via radio to a base station node, with inter-node distances of up to 420 m. The base station transmits data using a FreeWave radio modem, via a repeater, to a laptop located 4 km from the deployment site. Each node samples continuous sensor data and a simple event-detection algorithm is used to trigger data collection. When a sensor detects an event, it relays a short message to the base station via radio. If several nodes report an event within a short time interval, the last 60 seconds of data is downloaded from each node in turn. One of the sensor nodes is programmed to transmit continuous data; due to limited radio bandwidth, it is not possible to collect continuous data from all nodes in the array. A GPS receiver and time synchronization protocol is used to establish a global timebase across all sensor nodes.

  5. A Novel Wearable Sensor-Based Human Activity Recognition Approach Using Artificial Hydrocarbon Networks

    PubMed Central

    Ponce, Hiram; Martínez-Villaseñor, María de Lourdes; Miralles-Pechuán, Luis

    2016-01-01

    Human activity recognition has gained more interest in several research communities given that understanding user activities and behavior helps to deliver proactive and personalized services. There are many examples of health systems improved by human activity recognition. Nevertheless, the human activity recognition classification process is not an easy task. Different types of noise in wearable sensors data frequently hamper the human activity recognition classification process. In order to develop a successful activity recognition system, it is necessary to use stable and robust machine learning techniques capable of dealing with noisy data. In this paper, we presented the artificial hydrocarbon networks (AHN) technique to the human activity recognition community. Our artificial hydrocarbon networks novel approach is suitable for physical activity recognition, noise tolerance of corrupted data sensors and robust in terms of different issues on data sensors. We proved that the AHN classifier is very competitive for physical activity recognition and is very robust in comparison with other well-known machine learning methods. PMID:27399696

  6. A Novel Wearable Sensor-Based Human Activity Recognition Approach Using Artificial Hydrocarbon Networks.

    PubMed

    Ponce, Hiram; Martínez-Villaseñor, María de Lourdes; Miralles-Pechuán, Luis

    2016-01-01

    Human activity recognition has gained more interest in several research communities given that understanding user activities and behavior helps to deliver proactive and personalized services. There are many examples of health systems improved by human activity recognition. Nevertheless, the human activity recognition classification process is not an easy task. Different types of noise in wearable sensors data frequently hamper the human activity recognition classification process. In order to develop a successful activity recognition system, it is necessary to use stable and robust machine learning techniques capable of dealing with noisy data. In this paper, we presented the artificial hydrocarbon networks (AHN) technique to the human activity recognition community. Our artificial hydrocarbon networks novel approach is suitable for physical activity recognition, noise tolerance of corrupted data sensors and robust in terms of different issues on data sensors. We proved that the AHN classifier is very competitive for physical activity recognition and is very robust in comparison with other well-known machine learning methods. PMID:27399696

  7. Heavily irradiated N-in-p thin planar pixel sensors with and without active edges

    NASA Astrophysics Data System (ADS)

    Terzo, S.; Andricek, L.; Macchiolo, A.; Moser, H. G.; Nisius, R.; Richter, R. H.; Weigell, P.

    2014-05-01

    We present the results of the characterization of silicon pixel modules employing n-in-p planar sensors with an active thickness of 150 μm, produced at MPP/HLL, and 100-200 μm thin active edge sensor devices, produced at VTT in Finland. These thin sensors are designed as candidates for the ATLAS pixel detector upgrade to be operated at the HL-LHC, as they ensure radiation hardness at high fluences. They are interconnected to the ATLAS FE-I3 and FE-I4 read-out chips. Moreover, the n-in-p technology only requires a single side processing and thereby it is a cost-effective alternative to the n-in-n pixel technology presently employed in the LHC experiments. High precision beam test measurements of the hit efficiency have been performed on these devices both at the CERN SpS and at DESY, Hamburg. We studied the behavior of these sensors at different bias voltages and different beam incident angles up to the maximum one expected for the new Insertable B-Layer of ATLAS and for HL-LHC detectors. Results obtained with 150 μm thin sensors, assembled with the new ATLAS FE-I4 chip and irradiated up to a fluence of 4 × 1015 neq/cm2, show that they are excellent candidates for larger radii of the silicon pixel tracker in the upgrade of the ATLAS detector at HL-LHC. In addition, the active edge technology of the VTT devices maximizes the active area of the sensor and reduces the material budget to suit the requirements for the innermost layers. The edge pixel performance of VTT modules has been investigated at beam test experiments and the analysis after irradiation up to a fluence of 5 × 1015 neq/cm2 has been performed using radioactive sources in the laboratory.

  8. First tests of CHERWELL, a Monolithic Active Pixel Sensor: A CMOS Image Sensor (CIS) using 180 nm technology

    NASA Astrophysics Data System (ADS)

    Mylroie-Smith, James; Kolya, Scott; Velthuis, Jaap; Bevan, Adrian; Inguglia, Gianluca; Headspith, Jon; Lazarus, Ian; Lemon, Roy; Crooks, Jamie; Turchetta, Renato; Wilson, Fergus

    2013-12-01

    The Cherwell is a 4T CMOS sensor in 180 nm technology developed for the detection of charged particles. Here, the different test structures on the sensor will be described and first results from tests on the reference pixel variant are shown. The sensors were shown to have a noise of 12 e- and a signal to noise up to 150 in 55Fe.

  9. Spectral characterisation and noise performance of Vanilla—an active pixel sensor

    NASA Astrophysics Data System (ADS)

    Blue, Andrew; Bates, R.; Bohndiek, S. E.; Clark, A.; Arvanitis, Costas D.; Greenshaw, T.; Laing, A.; Maneuski, D.; Turchetta, R.; O'Shea, V.

    2008-06-01

    This work will report on the characterisation of a new active pixel sensor, Vanilla. The Vanilla comprises of 512×512 (25μm 2) pixels. The sensor has a 12 bit digital output for full-frame mode, although it can also be readout in analogue mode, whereby it can also be read in a fully programmable region-of-interest (ROI) mode. In full frame, the sensor can operate at a readout rate of more than 100 frames per second (fps), while in ROI mode, the speed depends on the size, shape and number of ROIs. For example, an ROI of 6×6 pixels can be read at 20,000 fps in analogue mode. Using photon transfer curve (PTC) measurements allowed for the calculation of the read noise, shot noise, full-well capacity and camera gain constant of the sensor. Spectral response measurements detailed the quantum efficiency (QE) of the detector through the UV and visible region. Analysis of the ROI readout mode was also performed. Such measurements suggest that the Vanilla APS (active pixel sensor) will be suitable for a wide range of applications including particle physics and medical imaging.

  10. Real-time method for establishing a detection map for a network of sensors

    DOEpatents

    Nguyen, Hung D; Koch, Mark W; Giron, Casey; Rondeau, Daniel M; Russell, John L

    2012-09-11

    A method for establishing a detection map of a dynamically configurable sensor network. This method determines an appropriate set of locations for a plurality of sensor units of a sensor network and establishes a detection map for the network of sensors while the network is being set up; the detection map includes the effects of the local terrain and individual sensor performance. Sensor performance is characterized during the placement of the sensor units, which enables dynamic adjustment or reconfiguration of the placement of individual elements of the sensor network during network set-up to accommodate variations in local terrain and individual sensor performance. The reconfiguration of the network during initial set-up to accommodate deviations from idealized individual sensor detection zones improves the effectiveness of the sensor network in detecting activities at a detection perimeter and can provide the desired sensor coverage of an area while minimizing unintentional gaps in coverage.

  11. Multifunction sensor for target recognition

    NASA Astrophysics Data System (ADS)

    James, William M.; Lindberg, Perry C.

    1993-09-01

    The U.S. Army has a critical need for the capability provided by a multifunction sensor. This is (in effect) a smart sensor system that can adapt to environmental conditions and adjust its mode of operation to effectively counter any threat it meets. It will have an intelligent signal processor which has all of the system's sensor signals to choose from. The processor chooses the appropriate signal information to rapidly detect, acquire, track, and automatically identify all targets in the vicinity of the sensor under a wide variety of battlefield scenarios and environmental conditions. The multiphenomenology signal information provides the flexibility to overcome the adverse effects of clutter, countermeasures (both active and passive), illumination, obscurants, target orientation, and weather. It should be noted, however, that the types of sensory information required is dependent on the mission and the operating environment. For instance, a strategic defense sensor operating in space can use (and will need) different types of sensor data than the multifunction sensor employed on an attack helicopter. In fact, the sensor configuration on a helicopter operating in Saudi Arabia may be quite different from one that is deployed to Vietnam. For the purpose of this paper we generalize about the technologies desired for an adaptable, `smart' sensor system. We do not specify a particular mission nor define a specific threat. However, in any case, we can assume the need to fuse sensor signal information in an intelligent processor to provide robust performance in the battlefield environment. 12

  12. EFFECT OF CANOPY DEPTH ON ESTIMATES OF CORN BIOMASS AND N STATUS USING ACTIVE SENSORS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our long-term research goal is to develop practical N application systems for on-the-go remote sensing to assess crop N status and only apply N where needed at times when the crop can most efficiently utilize N. Our preliminary testing of two active sensor systems (Crop Circle and GreenSeeker) has s...

  13. [High-Performance Active Pixel X-Ray Sensors for X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Bautz, Mark; Suntharalingam, Vyshnavi

    2005-01-01

    The subject grants support development of High-Performance Active Pixel Sensors for X-ray Astronomy at the Massachusetts Institute of Technology (MIT) Center for Space Research and at MIT's Lincoln Laboratory. This memo reports our progress in the second year of the project, from April, 2004 through the present.

  14. Improving in-season nitrogen recommendations for maize using an active sensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An active crop canopy reflectance sensor could be used to increase N-use efficiency in corn (Zea mays L.), if temporal and spatial variability in soil N availability and plant demand are adequately accounted for with an in-season N application. Our objective was to evaluate the success of using an a...

  15. Using an Active Sensor to Calculate Site-Specific Nitrogen Sidedress Recommendations for Corn in Pennsylvania

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active sensors mounted on typical agricultural equipment could potentially be used to improve N (nitrogen) fertilizer recommendations and minimize nitrate losses to the environment, if N status and Economic Optimum N Rate (EONR) can be accurately determined for corn (Zea mays L). This study examine...

  16. Hot pixel generation in active pixel sensors: dosimetric and micro-dosimetric response

    NASA Technical Reports Server (NTRS)

    Scheick, Leif; Novak, Frank

    2003-01-01

    The dosimetric response of an active pixel sensor is analyzed. heavy ions are seen to damage the pixel in much the same way as gamma radiation. The probability of a hot pixel is seen to exhibit behavior that is not typical with other microdose effects.

  17. Enzymatic synthesis of acyclic nucleoside thiophosphonate diphosphates: effect of the α-phosphorus configuration on HIV-1 RT activity.

    PubMed

    Priet, Stéphane; Roux, Loic; Saez-Ayala, Magali; Ferron, François; Canard, Bruno; Alvarez, Karine

    2015-05-01

    The acyclic nucleosides thiophosphonates (9-[2-(thiophosphonomethoxy)ethyl]adenine (S-PMEA) and (R)-9-[2-(thiophosphonomethoxy)propyl]adenine (S-PMPA), exhibit antiviral activity against HIV-1, -2 and HBV. Their diphosphate forms S-PMEApp and S-PMPApp, synthesized as stereoisomeric mixture, are potent inhibitors of wild-type (WT) HIV-1 RT. Understanding HIV-1 RT stereoselectivity, however, awaits resolution of the diphosphate forms into defined stereoisomers. To this aim, thiophosphonate monophosphates S-PMEAp and S-PMPAp were synthesized and used in a stereocontrolled enzyme-catalyzed phosphoryl transfer reaction involving either nucleoside diphosphate kinase (NDPK) or creatine kinase (CK) to obtain thiophosphonate diphosphates as separated isomers. We then quantified substrate preference of recombinant WT HIV-1 RT toward pure stereoisomers using in vitro steady-state kinetic analyses. The crystal structure of a complex between Dictyostelium NDPK and S-PMPApp at 2.32Å allowed to determine the absolute configuration at the α-phosphorus atom in relation to the stereo-preference of studied enzymes. The RP isomer of S-PMPApp and S-PMEApp are the preferred substrate over SP for both NDPK and HIV-1 RT. PMID:25766862

  18. Fast calcium sensor proteins for monitoring neural activity

    PubMed Central

    Badura, Aleksandra; Sun, Xiaonan Richard; Giovannucci, Andrea; Lynch, Laura A.; Wang, Samuel S.-H.

    2014-01-01

    Abstract. A major goal of the BRAIN Initiative is the development of technologies to monitor neuronal network activity during active information processing. Toward this goal, genetically encoded calcium indicator proteins have become widely used for reporting activity in preparations ranging from invertebrates to awake mammals. However, slow response times, the narrow sensitivity range of Ca2+ and in some cases, poor signal-to-noise ratio still limit their usefulness. Here, we review recent improvements in the field of neural activity-sensitive probe design with a focus on the GCaMP family of calcium indicator proteins. In this context, we present our newly developed Fast-GCaMPs, which have up to 4-fold accelerated off-responses compared with the next-fastest GCaMP, GCaMP6f. Fast-GCaMPs were designed by destabilizing the association of the hydrophobic pocket of calcium-bound calmodulin with the RS20 binding domain, an intramolecular interaction that protects the green fluorescent protein chromophore. Fast-GCaMP6f-RS06 and Fast-GCaMP6f-RS09 have rapid off-responses in stopped-flow fluorimetry, in neocortical brain slices, and in the intact cerebellum in vivo. Fast-GCaMP6f variants should be useful for tracking action potentials closely spaced in time, and for following neural activity in fast-changing compartments, such as axons and dendrites. Finally, we discuss strategies that may allow tracking of a wider range of neuronal firing rates and improve spike detection. PMID:25558464

  19. Recognition of military-specific physical activities with body-fixed sensors.

    PubMed

    Wyss, Thomas; Mäder, Urs

    2010-11-01

    The purpose of this study was to develop and validate an algorithm for recognizing military-specific, physically demanding activities using body-fixed sensors. To develop the algorithm, the first group of study participants (n = 15) wore body-fixed sensors capable of measuring acceleration, step frequency, and heart rate while completing six military-specific activities: walking, marching with backpack, lifting and lowering loads, lifting and carrying loads, digging, and running. The accuracy of the algorithm was tested in these isolated activities in a laboratory setting (n = 18) and in the context of daily military training routine (n = 24). The overall recognition rates during isolated activities and during daily military routine activities were 87.5% and 85.5%, respectively. We conclude that the algorithm adequately recognized six military-specific physical activities based on sensor data alone both in a laboratory setting and in the military training environment. By recognizing type of physical activities this objective method provides additional information on military-job descriptions. PMID:21121495

  20. Magneto-impedance sensor for quasi-noncontact monitoring of breathing, pulse rate and activity status

    NASA Astrophysics Data System (ADS)

    Corodeanu, S.; Chiriac, H.; Radulescu, L.; Lupu, N.

    2014-05-01

    Results on the development and testing of a novel magnetic sensor based on the detection of the magneto-impedance variation due to changes in the permeability of an amorphous wire are reported. The proposed application is the quasi-noncontact monitoring of the breathing frequency and heart rate for diagnosing sleep disorders. Patient discomfort is significantly decreased by transversally placing the sensitive element onto the surface of a flexible mattress in order to detect its deformation associated with cardiorespiratory activity and body movements. The developed sensor has a great application potential in monitoring the vital signs during sleep, with special advantages for children sleep monitoring.

  1. Characterisation of Vanilla—A novel active pixel sensor for radiation detection

    NASA Astrophysics Data System (ADS)

    Blue, A.; Bates, R.; Laing, A.; Maneuski, D.; O'Shea, V.; Clark, A.; Prydderch, M.; Turchetta, R.; Arvanitis, C.; Bohndiek, S.

    2007-10-01

    Novel features of a new monolithic active pixel sensor, Vanilla, with 520×520 pixels ( 25 μm square) has been characterised for the first time. Optimisation of the sensor operation was made through variation of frame rates, integration times and on-chip biases and voltages. Features such as flushed reset operation, ROI capturing and readout modes have been fully tested. Stability measurements were performed to test its suitablility for long-term applications. These results suggest the Vanilla sensor—along with bio-medical and space applications—is suitable for use in particle physics experiments.

  2. The importance of behavior theory in control system modeling of physical activity sensor data.

    PubMed

    Riley, William T; Martin, Cesar A; Rivera, Daniel E

    2014-01-01

    Among health behaviors, physical activity has the most extensive record of research using passive sensors. Control systems and other system dynamic approaches have long been considered applicable for understanding human behavior, but only recently has the technology provided the precise and intensive longitudinal data required for these analytic approaches. Although sensors provide intensive data on the patterns and variations of physical activity over time, the influences of these variations are often unmeasured. Health behavior theories provide an explanatory framework of the putative mediators of physical activity changes. Incorporating the intensive longitudinal measurement of these theoretical constructs is critical to improving the fit of control system model of physical activity and for advancing behavioral theory. Theory-based control models also provide guidance on the nature of the controllers which serve as the basis for just-in-time adaptive interventions based on these control system models. PMID:25571577

  3. Redox Active Thiol Sensors of Oxidative and Nitrosative Stress

    PubMed Central

    2012-01-01

    Abstract Significance: The reactivity of the thiol in the side chain of cysteines is exploited by bacterial regulatory proteins that sense and respond to reactive oxygen and nitrogen species. Recent Advances: Charged residues and helix dipoles diminish the pKa of redox active cysteines, resulting in a thiolate that is stabilized by neighboring polar amino acids. The reaction of peroxides with thiolates generates a sulfenic acid (–SOH) intermediate that often gives rise to a reversible disulfide bond. Peroxide-induced intramolecular and intermolecular disulfides and intermolecular mixed disulfides modulate the signaling activity of members of the LysR/OxyR, MarR/OhrR, and RsrA family of transcriptional regulators. Thiol-dependent regulators also help bacteria resist the nitrosative and nitroxidative stress. −SOHs, mixed disulfides, and S-nitrosothiols are some of the post-translational modifications induced by nitrogen oxides in the thiol groups of OxyR and SsrB bacterial regulatory proteins. Sulfenylation, disulfide bond formation, S-thiolation, and S-nitrosylation are reversible modifications amenable to feedback regulation by antioxidant and antinitrosative repair systems. The structural and functional changes engaged in the thiol-dependent sensing of reactive species have been adopted by several regulators to foster bacterial virulence during exposure to products of NADPH phagocyte oxidase and inducible nitric oxide synthase. Critical Issues: Investigations with LysR/OxyR, MarR/OhrR, and RsrA family members have helped in an understanding of the mechanisms by which thiols in regulatory proteins react with reactive species, thereby activating antioxidant and antinitrosative gene expression. Future Directions: To define the determinants that provide selectivity of redox active thiolates for some reactive species but not others is an important challenge for future investigations. Antioxid. Redox Signal. 17, 1201–1214. PMID:22257022

  4. Fingernail Configuration

    PubMed Central

    Jung, Jin Woo; Shin, Jun Ho; Kwon, Yu Jin; Hwang, Jae Ha; Lee, Sam Yong

    2015-01-01

    Background A number of conditions can alter a person's fingernail configuration. The ratio between fingernail width and length (W/L) is an important aesthetic criterion, and some underlying diseases can alter the size of the fingernail. Fingernail curvature can be altered by systemic disorders or disorders of the fingernail itself. Although the shape and curvature of the fingernail can provide diagnostic clues for various diseases, few studies have precisely characterized normal fingernail configuration. Methods We measured the W/L ratio of the fingernail, transverse fingernail curvature, hand length, hand breadth, and distal interphalangeal joint width in 300 volunteers with healthy fingernails. We also investigated whether age, sex, height, and handedness influenced the fingernail W/L ratio and transverse fingernail curvature. Results In women, fingernail W/L ratios were similar across all five fingers, and were lower than those in men. The highest value of transverse fingernail curvature was found in the thumb, followed by the index, middle, ring, and little fingers. Handedness and aging influenced transverse fingernail curvature, but not the fingernail W/L ratio. Fingernails were flatter on the dominant hand than on the non-dominant hand. The radius of transverse fingernail curvature increased with age, indicating that fingernails tended to flatten with age. Conclusions Our quantitative data on fingernail configuration can be used as a reference range for diagnosing various diseases and deformities of the fingernail, and for performing reconstructive or aesthetic fingernail surgery. PMID:26618124

  5. An active view planning method for mobile robots using a trinocular visual sensor

    NASA Astrophysics Data System (ADS)

    Kim, Min Y.; Cho, Hyungsuck

    2003-10-01

    The ability of mobile robots to perceive and recognize environments is essential for autonomous navigation. To improve the performance of autonomous environment perception for mobile robots, it is important to effectively plan the next pose (position and orientation) of the sensor system at a current navigation state. In this paper, we propose a next-view-planning method for autonomous map construction needed for mobile robots with visual range sensor systems. The proposed view-planning method mimics the decision-making method of human beings, and uses the occlusion information reduced from the geometric relationship between the sensor view and objects as an important clue for the next sensor view planning. The proposed view-planning algorithms are developed in the following steps: 1) Given a prior map and range measurements sensed at a current location of the mobile robot, it is determined which parts in the map are interested in a view of solving the map uncertainty. 2) Based on the selected potential regions, some candidate poses of the sensor system for the next environment sensing are carefully generated. 3) The created candidates are evaluated by using a specially designed evaluation parameter, and the best one of them is selected as a next sensor position based on a fuzzy decision-making method. In this work, the principle of the view planning method is described in detail, and a series of experimental tests is performed to show the feasibility of the method for autonomous map building. For sensing the environments, an active trinocular vision sensor using laser structured light is utilized, which is mounted on the pan-tilt mechanism of the mobile robot, which is composed of a laser stripe projector and two cameras.

  6. Unobtrusive measurement of indoor energy expenditure using an infrared sensor-based activity monitoring system.

    PubMed

    Hwang, Bosun; Han, Jonghee; Choi, Jong Min; Park, Kwang Suk

    2008-11-01

    The purpose of this study was to develop an unobtrusive energy expenditure (EE) measurement system using an infrared (IR) sensor-based activity monitoring system to measure indoor activities and to estimate individual quantitative EE. IR-sensor activation counts were measured with a Bluetooth-based monitoring system and the standard EE was calculated using an established regression equation. Ten male subjects participated in the experiment and three different EE measurement systems (gas analyzer, accelerometer, IR sensor) were used simultaneously in order to determine the regression equation and evaluate the performance. As a standard measurement, oxygen consumption was simultaneously measured by a portable metabolic system (Metamax 3X, Cortex, Germany). A single room experiment was performed to develop a regression model of the standard EE measurement from the proposed IR sensor-based measurement system. In addition, correlation and regression analyses were done to compare the performance of the IR system with that of the Actigraph system. We determined that our proposed IR-based EE measurement system shows a similar correlation to the Actigraph system with the standard measurement system. PMID:19035796

  7. Programmable active pixel sensor to investigate neural interactions within the retina

    NASA Astrophysics Data System (ADS)

    Hart, Matthew D.; Prydderch, Mark L.; Morrison, James D.; Murdoch, Derek; Mathieson, Keith

    2009-05-01

    Detection of the visual scene by the eye and the resultant neural interactions of the retina-brain system give us our perception of sight. We have developed an Active Pixel Sensor (APS) to be used as a tool for both furthering understanding of these interactions via experimentation with the retina and to make developments towards a realisable retinal prosthesis. The sensor consists of 469 pixels in a hexagonal array. The pixels are interconnected by a programmable neural network to mimic lateral interactions between retinal cells. Outputs from the sensor are in the form of biphasic current pulse trains suitable to stimulate retinal cells via a biocompatible array. The APS will be described with initial characterisation and test results.

  8. Stress-strain sensor for monitoring seismic precursors and fault activities in the sand

    NASA Astrophysics Data System (ADS)

    Du, Qiujiao; Sun, Wei; Zeng, Zuoxun

    2016-04-01

    In this paper, a sensor to monitor stress-strain signals in a granular medium is used to detect seismic precursory information. Compared with the widely used sensors of borehole stress in the rock, the sensor has more convenient operation, higher output sensitivity, compactness and farther propagation effect. The stress and strain changes before Pu'er Ms6.4 earthquake in China are recorded by Beijing and Xinmin stations, and its corresponding fault activities are analyzed. Study indicates anomalous amplitude of strain signal reaches 10 times higher than that of ordinary background, and compressive oscillation and extensional oscillation occurred constantly before the earthquake. The method and results presented in the paper provide a new way for investigating seismic precursors for shallow-source earthquakes.

  9. Active control for vibration suppression in a flexible beam using a modal domain optical fiber sensor

    NASA Technical Reports Server (NTRS)

    Cox, D. E.; Lindner, D. K.

    1991-01-01

    An account is given of the use of a modal-domain (MD) fiber-optic sensor as an active control system component for vibration suppression, whose output is proportional to the integral of the axial strain along the optical fiber. When an MD sensor is attached to, or embedded in, a flexible structure, it senses the strain in the structure along its gage length. On the basis of the present integration of the sensor model into a flexible-structure model, it becomes possible to design a control system with a dynamic compensator which adds damping to the low-order modes of the flexible structure. This modeling procedure has been experimentally validated.

  10. Integrating Multiple Space Ground Sensors to Track Volcanic Activity

    NASA Technical Reports Server (NTRS)

    Chien, Steve; Davies, Ashley; Doubleday, Joshua; Tran, Daniel; Jones, Samuel; Kjartansson, Einar; Thorsteinsson, Hrobjartur; Vogfjord, Kristin; Guomundsson, Magnus; Thordarson, Thor; Mandl, Daniel

    2011-01-01

    Volcanic activity can occur with little or no warning. Increasing numbers of space borne assets can enable coordinated measurements of volcanic events to enhance both scientific study and hazard response. We describe the use of space and ground measurements to target further measurements as part of a worldwide volcano monitoring system. We utilize a number of alert systems including the MODVOLC, GOESVOLC, US Air Force Weather Advisory, and Volcanic Ash Advisory Center (VAAC) alert systems. Additionally we use in-situ data from ground instrumentation at a number of volcanic sites, including Iceland.

  11. A Sensor Fault Detection Methodology applied to Piezoelectric Active Systems in Structural Health Monitoring Applications

    NASA Astrophysics Data System (ADS)

    Tibaduiza, D.; Anaya, M.; Forero, E.; Castro, R.; Pozo, F.

    2016-07-01

    Damage detection is the basis of the damage identification task in Structural Health Monitoring. A good damage detection process can ensure the adequate work of a SHM System because allows to know early information about the presence of a damage in a structure under evaluation. However this process is based on the premise that all sensors are well installed and they are working properly, however, it is not true all the time. Problems such as debonding, cuts and the use of the sensors under different environmental and operational conditions result in changes in the vibrational response and a bad functioning in the SHM system. As a contribution to evaluate the state of the sensors in a SHM system, this paper describes a methodology for sensor fault detection in a piezoelectric active system. The methodology involves the use of PCA for multivariate analysis and some damage indices as pattern recognition technique and is tested in a blade from a wind turbine where different scenarios are evaluated including sensor cuts and debonding.

  12. The solution configurations of inactive and activated DntR have implications for the sliding dimer mechanism of LysR transcription factors

    PubMed Central

    Lerche, Michael; Dian, Cyril; Round, Adam; Lönneborg, Rosa; Brzezinski, Peter; Leonard, Gordon A.

    2016-01-01

    LysR Type Transcriptional Regulators (LTTRs) regulate basic metabolic pathways or virulence gene expression in prokaryotes. Evidence suggests that the activation of LTTRs involves a conformational change from an inactive compact apo- configuration that represses transcription to an active, expanded holo- form that promotes it. However, no LTTR has yet been observed to adopt both configurations. Here, we report the results of structural studies of various forms of the LTTR DntR. Crystal structures of apo-DntR and of a partially autoinducing mutant H169T-DntR suggest that active and inactive DntR maintain a compact homotetrameric configuration. However, Small Angle X-ray Scattering (SAXS) studies on solutions of apo-, H169T- and inducer-bound holo-DntR indicate a different behaviour, suggesting that while apo-DntR maintains a compact configuration in solution both H169T- and holo-DntR adopt an expanded conformation. Models of the SAXS-obtained solution conformations of apo- and holo-DntR homotetramers in complex with promoter-operator region DNA are consistent with previous observations of a shifting of LTTR DNA binding sites upon activation and a consequent relaxation in the bend of the promoter-operator region DNA. Our results thus provide clear evidence at the molecular level which strongly supports the ‘sliding dimer’ hypothesis concerning LTTR activation mechanisms. PMID:26817994

  13. Characterization of real objects by an active electrolocation sensor

    NASA Astrophysics Data System (ADS)

    Metzen, Michael G.; Al Ghouz, Imène; Krueger, Sandra; Bousack, Herbert; von der Emde, Gerhard

    2012-04-01

    Weakly electric fish use a process called 'active electrolocation' to orientate in their environment and to localize objects based on their electrical properties. To do so, the fish discharge an electric organ which emits brief electrical current pulses (electric organ discharge, EOD) and in return sense the generated electric field which builds up surrounding the animal. Caused by the electrical properties of nearby objects, fish measure characteristic signal modulations with an array of electroreceptors in their skin. The fish are able to gain important information about the geometrical properties of an object as well as its complex impedance and its distance. Thus, active electrolocation is an interesting feature to be used in biomimetic approaches. We used this sensory principle to identify different insertions in the walls of Plexiglas tubes. The insertions tested were composed of aluminum, brass and graphite in sizes between 3 and 20 mm. A carrier signal was emitted and perceived with the poles of a commercial catheter for medical diagnostics. Measurements were performed with the poles separated by 6.3 to 55.3 mm. Depending on the length of the insertion in relation to the sender-receiver distance, we observed up to three peaks in the measured electric images. The first peak was affected by the material of the insertion, while the distance between the second and third peak strongly correlated with the length of the insertion. In a second experiment we tested whether various materials could be detected by using signals of different frequency compositions. Based on their electric images we were able to discriminate between objects having different resistive properties, but not between objects of complex impedances.

  14. [Implantable cardioverter/defibrillator: long-term stability of the defibrillation threshold with a unipolar electrode configuration (active-can")].

    PubMed

    Knuefermann, P; Wolpert, C; Spehl, S; Korte, T; Manz, M; Lüderitz, B; Jung, W

    2000-09-01

    The majority of cardioverter/defibrillator (ICD) implantations are currently performed with a non-thoracotomy approach. From November 1993 to January 1995, 46 patients underwent implantation of a PCD 7219C with an "active-can" lead configuration at our institution. While the chronic stability of the defibrillation threshold (DFT) for an epicardial lead system is well established, the results are still inconsistent for non-thoracotomy lead systems. Accordingly, the aim of the present study was to compare the acute and chronic defibrillation thresholds of the ICDs implanted with an "active-can" lead system in order to assess the chronic stability of these systems. The defibrillation energy requirements were measured at implant, prior to hospital discharge, three, six and twelve months after implantation of the defibrillator. The patient group consisted of 8 females and 38 males with a mean age of 57.2 years. The mean left ventricular ejection fraction was 43.8%. The most frequent underlying heart disease was coronary artery disease in 31 of 46 patients. Eight patients had idiopathic dilated cardiomyopathy. In 39 of 46 patients, the defibrillation threshold could be successfully determined at all 4 time points after implantation. The mean defibrillation energy requirement at the time of implantation was 9.2 +/- 5.9 Joules (J). The subsequent mean energy requirements were 7.6 +/- 4.8 J at pre-hospital discharge, 8.6 +/- 5.7 J at the 3 month, 8.1 +/- 6.0 J at the 6 month and 8.6 +/- 5.8 J at the 12 month follow-up visits. The mean defibrillation threshold was lowest at the time of prehospital discharge, significantly lower than at the time of initial implantation (p = 0.021). However, at all later time points up to one year, there was no significant difference in the DFT as compared with the time of initial implantation. Comparing the DFT at the time of implantation and the DFT at all other time points, there were no significant differences (9.23 vs. 8.56 J, p = 0

  15. Human Activity Recognition from Environmental Background Sounds for Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Zhan, Yi; Nishimura, Jun; Kuroda, Tadahiro

    Sound feature extraction Mel Frequency Cepstral Coefficients (MFCC) and Vector Quantization (VQ) classification Linde-Buzo-Gray algorithm (LBG) algorithms are applied for recognizing the background sounds in the human daily activities. Applying these algorithms to twenty typical daily activity sounds, average recognition accuracy of 93.8% can be achieved. In these algorithms, how three parameters (i.e., Mel filters number, frame-to-frame overlap and LBG codebook cluster number) affect system's calculation burden and accuracy is also investigated. By adjusting these three parameters to an optimized combination, the multiplication and addition calculation burden can be reduced by 87.0% and 87.1% individually while maintaining the system's average accuracy rate at 92.5%. This is promising for future integration with other sensor (s) to fulfill daily activity recognition by using power aware Wireless Sensor Networks (WSN) systems.

  16. Determination of bacterial activity by use of an evanescent-wave fiber-optic sensor.

    PubMed

    John, M Shelly; Kishen, Anil; Sing, Lim Chu; Asundi, Anand

    2002-12-01

    A novel technique based on fiber-optic evanescent-wave spectroscopy is proposed for the detection of bacterial activity in human saliva. The sensor determines th e specific concentration of Streptococcus mutans in saliva, which is a major causative factor in dental caries. In this design, one prepares the fiber-optic bacterial sensor by replacing a portion of the cladding region of a multimode fiber with a dye-encapsulated xerogel, using the solgel technique. The exponential decay of the evanescent wave at the core-cladding interface of a multimode fiber is utilized for the determination of bacterial activity in saliva. The acidogenic profile of Streptococcus mutans is estimated by use of evanescent-waveabsorption spectra at various levels of bacterial activity. PMID:12477126

  17. Genetically encoded proton sensors reveal activity-dependent pH changes in neurons

    PubMed Central

    Raimondo, Joseph V.; Irkle, Agnese; Wefelmeyer, Winnie; Newey, Sarah E.; Akerman, Colin J.

    2011-01-01

    The regulation of hydrogen ion concentration (pH) is fundamental to cell viability, metabolism, and enzymatic function. Within the nervous system, the control of pH is also involved in diverse and dynamic processes including development, synaptic transmission, and the control of network excitability. As pH affects neuronal activity, and can also itself be altered by neuronal activity, the existence of tools to accurately measure hydrogen ion fluctuations is important for understanding the role pH plays under physiological and pathological conditions. Outside of their use as a marker of synaptic release, genetically encoded pH sensors have not been utilized to study hydrogen ion fluxes associated with network activity. By combining whole-cell patch clamp with simultaneous two-photon or confocal imaging, we quantified the amplitude and time course of neuronal, intracellular, acidic transients evoked by epileptiform activity in two separate in vitro models of temporal lobe epilepsy. In doing so, we demonstrate the suitability of three genetically encoded pH sensors: deGFP4, E2GFP, and Cl-sensor for investigating activity-dependent pH changes at the level of single neurons. PMID:22666186

  18. TiN thin film deposition by cathodic cage discharge: effect of cage configuration and active species

    NASA Astrophysics Data System (ADS)

    de Freitas Daudt, N.; Pereira Barbosa, J. C.; Cavalcante Braz, D.; Barbalho Pereira, M.; Alves Junior, C.

    2012-12-01

    Plasma cathodic cage technique was developed recently in order to eliminate phenomena such as edge effects and overheating, which occur during conventional nitriding processes. In this work, the effect of plasma active species and cage configurations during thin film deposition of TiN were studied. This compound was chosen because its properties are very sensitive to slight variations in chemical composition and film thickness, becoming a good monitoring tool in fabrication process control. In order to verify the effect of cage geometry on the discharge and characteristics of the grown film, a cage made of titanium was used with different numbers and distribution of holes. Furthermore, different amounts of hydrogen were added to the Ar + N2 plasma atmosphere. Flow rates of Ar and N2 gas were fixed at 4 and 3 sccm, respectively and flow rates of H2 gas was 0, 1 and 2 sccm. Plasma species, electrical discharge and physical characteristics of the grown film were analyzed by Optical Emission Spectroscopy (OES), Atomic Force Microscopy (AFM), X-Ray Diffraction. It was observed by OES that the luminous intensity associated to Hα species is not proportional to flow rate of H2 gas. Electrical efficiency of the system, crystal structure and topography of the TiN film are strongly influenced by this behavior. For constant flow rate of H2 gas, it was found that with more holes at the top of the cage, deposition rate, crystallinity and roughness are higher, if compared to cages with a small number of holes at the top of cage. On the other hand, the opposite behavior was observed when more holes were located at the sidewall of cage.

  19. Monitoring respiration and cardiac activity using fiber Bragg grating-based sensor.

    PubMed

    Dziuda, Lukasz; Skibniewski, Franciszek Wojciech; Krej, Mariusz; Lewandowski, Jaroslaw

    2012-07-01

    This paper shows the design of a fiber-based sensor for living activities in human body and the results of a laboratory evaluation carried out on it. The authors have developed a device that allows for monitoring the vibrations of human body evoked by living activities--breathing and cardiac rhythm. The device consists of a Bragg grating inscribed into a single mode optical fiber and operating on a wavelength of around 1550 nm. The fiber Bragg grating (FBG) is mounted inside a pneumatic cushion to be placed between the backrest of the seat and the back of the monitored person. Deformations of the cushion, involving deformations of the FBG, are proportional to the vibrations of the body leaning on the cushion. Laboratory studies have shown that the sensor allows for obtaining dynamic strains on the sensing FBG in the range of 50-124 μ strain caused by breathing and approximately 8.3 μstrain induced by heartbeat, which are fully measurable by today's FBG interrogation systems. The maximum relative measurement error of the presented sensor is 12%. The sensor's simple design enables it to be easily implemented in pilot's and driver's seats for monitoring the physiological condition of pilots and drivers. PMID:22514201

  20. Active vision and sensor fusion for inspection of metallic surfaces

    NASA Astrophysics Data System (ADS)

    Puente Leon, Fernando; Beyerer, Juergen

    1997-09-01

    This paper deals with strategies for reliably obtaining the edges and the surface texture of metallic objects. Since illumination is a critical aspect regarding robustness and image quality, it is considered here as an active component of the image acquisition system. The performance of the methods presented is demonstrated -- among other examples -- with images of needles for blood sugar tests. Such objects show an optimized form consisting of several planar grinded surfaces delimited by sharp edges. To allow a reliable assessment of the quality of each surface, and a measurement of their edges, methods for fusing data obtained with different illumination constellations were developed. The fusion strategy is based on the minimization of suitable energy functions. First, an illumination-based segmentation of the object is performed. To obtain the boundaries of each surface, directional light-field illumination is used. By formulating suitable criteria, nearly binary images are selected by variation of the illumination direction. Hereafter, the surface edges are obtained by fusing the contours of the areas obtained before. Following, an optimally illuminated image is acquired for each surface of the object by varying the illumination direction. For this purpose, a criterion describing the quality of the surface texture has to be maximized. Finally, the images of all textured surfaces of the object are fused to an improved result, in which the whole object is contained with high contrast. Although the methods presented were designed for inspection of needles, they also perform robustly in other computer vision tasks where metallic objects have to be inspected.

  1. ISDSN Sensor System Phase One Test Report

    SciTech Connect

    Gail Heath

    2011-09-01

    This Phase 1 Test Report documents the test activities and results completed for the Idaho National Laboratory (INL) sensor systems that will be deployed in the meso-scale test bed (MSTB) at Florida International University (FIU), as outlined in the ISDSN-MSTB Test Plan. This report captures the sensor system configuration tested; test parameters, testing procedure, any noted changes from the implementation plan, acquired test data sets, and processed results.

  2. Multiple signals modulate the activity of the complex sensor kinase TodS

    PubMed Central

    Silva-Jiménez, Hortencia; Ortega, Álvaro; García-Fontana, Cristina; Ramos, Juan Luis; Krell, Tino

    2015-01-01

    The reason for the existence of complex sensor kinases is little understood but thought to lie in the capacity to respond to multiple signals. The complex, seven-domain sensor kinase TodS controls in concert with the TodT response regulator the expression of the toluene dioxygenase pathway in Pseudomonas putida F1 and DOT-T1E. We have previously shown that some aromatic hydrocarbons stimulate TodS activity whereas others behave as antagonists. We show here that TodS responds in addition to the oxidative agent menadione. Menadione but no other oxidative agent tested inhibited TodS activity in vitro and reduced PtodX expression in vivo. The menadione signal is incorporated by a cysteine-dependent mechanism. The mutation of the sole conserved cysteine of TodS (C320) rendered the protein insensitive to menadione. We evaluated the mutual opposing effects of toluene and menadione on TodS autophosphorylation. In the presence of toluene, menadione reduced TodS activity whereas toluene did not stimulate activity in the presence of menadione. It was shown by others that menadione increases expression of glucose metabolism genes. The opposing effects of menadione on glucose and toluene metabolism may be partially responsible for the interwoven regulation of both catabolic pathways. This work provides mechanistic detail on how complex sensor kinases integrate different types of signal molecules. PMID:24986263

  3. A Human Activity Recognition System Using Skeleton Data from RGBD Sensors

    PubMed Central

    Gasparrini, Samuele

    2016-01-01

    The aim of Active and Assisted Living is to develop tools to promote the ageing in place of elderly people, and human activity recognition algorithms can help to monitor aged people in home environments. Different types of sensors can be used to address this task and the RGBD sensors, especially the ones used for gaming, are cost-effective and provide much information about the environment. This work aims to propose an activity recognition algorithm exploiting skeleton data extracted by RGBD sensors. The system is based on the extraction of key poses to compose a feature vector, and a multiclass Support Vector Machine to perform classification. Computation and association of key poses are carried out using a clustering algorithm, without the need of a learning algorithm. The proposed approach is evaluated on five publicly available datasets for activity recognition, showing promising results especially when applied for the recognition of AAL related actions. Finally, the current applicability of this solution in AAL scenarios and the future improvements needed are discussed. PMID:27069469

  4. Quantum dot based enzyme activity sensors present deviations from Michaelis-Menten kinetic model

    NASA Astrophysics Data System (ADS)

    Díaz, Sebastián. A.; Brown, Carl W.; Malanoski, Anthony P.; Oh, Eunkeu; Susumu, Kimihiro; Medintz, Igor L.

    2016-03-01

    Nanosensors employing quantum dots (QDs) and enzyme substrates with fluorescent moieties offer tremendous promise for disease surveillance/diagnostics and as high-throughput co-factor assays. Advantages of QDs over other nanoscaffolds include their small size and inherent photochemical properties such as size tunable fluorescence, ease in attaching functional moieties, and resistance to photobleaching. These properties make QDs excellent Förster Resonance Energy Transfer (FRET) donors; well-suited for rapid, optical measurement applications. We report enzyme sensors designed with a single FRET donor, the QD donor acting as a scaffold to multiple substrates or acceptors. The QD-sensor follows the concrete activity of the enzyme, as compared to the most common methodologies that quantify the enzyme amount or its mRNA precursor. As the sensor reports on the enzyme activity in real-time we can actively follow the kinetics of the enzyme. Though classic Michaelis-Menten (MM) parameters can be obtained to describe the activity. In the course of these experiments deviations, both decreasing and increasing the kinetics, from the common MM model were observed upon close examinations. From these observations additional experiments were undertaken to understand the varying mechanisms. Different enzymes can present different deviations depending on the chosen target, e.g. trypsin appears to present a positive hopping mechanism while collagenase demonstrates a QD caused reversible inhibition.

  5. Photo-activated luminescence sensor and method of detecting trichloroethylene and related volatile organochloride compounds

    DOEpatents

    Dinh, T.V.

    1996-06-11

    A sensor for detecting trichloroethylene and related volatile organochloride compounds uses a photo-activator that produces a photo-product complex with the contaminant. Characteristics of the light emitted from the complex will indicate the presence of the contaminant. A probe containing the photo-activator has an excitation light interface and a contaminant interface. One particular embodiment uses a porous membrane as the contaminant interface, so that the contaminant can migrate there through to the photo-activator and thereby form the complex. 23 figs.

  6. Photo-activated luminescence sensor and method of detecting trichloroethylene and related volatile organochloride compounds

    DOEpatents

    Dinh, Tuan V.

    1996-01-01

    A sensor for detecting trichloroethylene and related volatile organochloride compounds uses a photo-activator that produces a photo-product complex with the contaminant. Characteristics of the light emitted from the complex will indicate the presence of the contaminant. A probe containing the photo-activator has an excitation light interface and a contaminant interface. One particular embodiment uses a porous membrane as the contaminant interface, so that the contaminant can migrate therethrough to the photo-activator and thereby form the complex.

  7. ALPIDE, the Monolithic Active Pixel Sensor for the ALICE ITS upgrade

    NASA Astrophysics Data System (ADS)

    Mager, M.

    2016-07-01

    A new 10 m2 inner tracking system based on seven concentric layers of Monolithic Active Pixel Sensors will be installed in the ALICE experiment during the second long shutdown of LHC in 2019-2020. The monolithic pixel sensors will be fabricated in the 180 nm CMOS Imaging Sensor process of TowerJazz. The ALPIDE design takes full advantage of a particular process feature, the deep p-well, which allows for full CMOS circuitry within the pixel matrix, while at the same time retaining the full charge collection efficiency. Together with the small feature size and the availability of six metal layers, this allowed a continuously active low-power front-end to be placed into each pixel and an in-matrix sparsification circuit to be used that sends only the addresses of hit pixels to the periphery. This approach led to a power consumption of less than 40 mWcm-2, a spatial resolution of around 5 μm, a peaking time of around 2 μs, while being radiation hard to some 1013 1 MeVneq /cm2, fulfilling or exceeding the ALICE requirements. Over the last years of R & D, several prototype circuits have been used to verify radiation hardness, and to optimize pixel geometry and in-pixel front-end circuitry. The positive results led to a submission of full-scale (3 cm×1.5 cm) sensor prototypes in 2014. They are being characterized in a comprehensive campaign that also involves several irradiation and beam tests. A summary of the results obtained and prospects towards the final sensor to instrument the ALICE Inner Tracking System are given.

  8. An Optical Actuation System and Curvature Sensor for a MR-compatible Active Needle

    PubMed Central

    Ryu, Seok Chang; Quek, Zhan Fan; Renaud, Pierre; Black, Richard J.; Daniel, Bruce L.; Cutkosky, Mark R.

    2015-01-01

    A side optical actuation method is presented for a slender MR-compatible active needle. The needle includes an active region with a shape memory alloy (SMA) wire actuator, where the wire generates a contraction force when optically heated by a laser delivered though optical fibers, producing needle tip bending. A prototype, with multiple side heating spots, demonstrates twice as fast an initial response compared to fiber tip heating when 0.8 W of optical power is applied. A single-ended optical sensor with a gold reflector is also presented to measure the curvature as a function of optical transmission loss. Preliminary tests with the sensor prototype demonstrate approximately linear response and a repeatable signal, independent of the bending history. PMID:26509099

  9. Integration of an Active Sensor Algorithm with Soil-Based Management Zones for Nitrogen Management in Corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active crop canopy sensors have been studied as a possible proximal sensing tool to assess in-season plant N status and direct spatially-variable N applications, and thereby increase NUE compared to uniform N application. A sensor-based N application algorithm was previously developed on small plots...

  10. Active crop canopy sensor optimal spatial scale for in-season variable-rate nitrogen application in corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active crop canopy reflectance sensors have shown to be an efficient method for assessing spatially-variable crop nitrogen (N) need and controlling remedial in-season N applications in wheat. Recently, these sensors have been studied for N application in corn. This study will be conducted during the...

  11. Sensor-actuator coupled device for active tracheal tube using solid polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    Ihara, Tadashi; Nakamura, Taro; Mukai, Toshiharu; Asaka, Kinji

    2007-04-01

    A sensor-actuator coupled device was developed using solid polymer electrolyte membrane (SPM) as an active tracheal tube for ventilator. Active tracheal tube is a novel type of tube for ventilator that removes patient's phlegm automatically upon sensing the narrowing of trachea by phlegm. This type of active tube is extremely useful in clinical settings as currently the sole measure to remove phlegm from patient's tube is to do it manually by a nurse every few hours. As SPM works both as a sensor and an actuator, an effective compact device was developed. SPM based sensor-actuator coupled device was fabricated with modified gold plating method. Prepared SPM was fixed as an array on a plastic pipe of diameter 22 mm and was connected to a ventilator circuit and driven by a ventilator with a volume control ventilation (VCV) mode. SPM was connected both to a sensing unit and an actuation unit. Generated voltage developed by the membrane with the setting of the maximum pressure from 5 cmH IIO to 20 cmH IIO was in order of several hundred μV. SPM sensor demonstrated a biphasic response to the ventilator flow. The sensor data showed nearly linearly proportional voltage development to the intra-tracheal pressure. The sensed signal was filtered and digitized with an A/D converting unit on a PC board. A real time operating program was used to detect the sensed signal that indicates the narrowing of trachea. The program then activated a driving signal to control the actuation of the membrane. The signal was sent to a D/A converting unit. The output of the D/A unit was sent to an amplifier and the galvanostat unit which drives the membrane with constant current regardless of the change in the load. It was demonstrated that the sensor-actuator unit detects the narrowing of trachea within several hundreds milli-seconds and responds by actuating the same membrane with the driving voltage of 3-4 V and driving current of several hundred milli-ampere for each membrane. SPM array

  12. The Correlation of Active and Passive Microwave Outputs for the Skylab S-193 Sensor

    NASA Technical Reports Server (NTRS)

    Krishen, K.

    1976-01-01

    This paper presents the results of the correlation analysis of the Skylab S-193 13.9 GHz Radiometer/Scatterometer data. Computer analysis of the S-193 data shows more than 50 percent of the radiometer and scatterometer data are uncorrelated. The correlation coefficients computed for the data gathered over various ground scenes indicates the desirability of using both active and passive sensors for the determination of various Earth phenomena.

  13. The correlation of active and passive microwave data for the Skylab S-193 sensor

    NASA Technical Reports Server (NTRS)

    Krishen, Kumar

    1993-01-01

    This paper presents the results of the correlation analysis of the Skylab S-193 13.9 GHz Radiometer/Scatterometer data. Computer analysis of the S-193 data shows more than 50 percent of the radiometer and scatterometer data are uncorrelated. The correlation coefficients computed for the data gathered over various ground scenes indicates the desirability of using both active and passive sensors for the determination of various Earth phenomena.

  14. Systematic approach to development of pressure sensors using dielectric electro-active polymer membranes

    NASA Astrophysics Data System (ADS)

    York, A.; Dunn, J.; Seelecke, S.

    2013-09-01

    Dielectric electro-active polymers (DEAPs) have become attractive materials for various actuation and sensing applications due to their high energy and power density, high efficiency, light weight, and fast response speed. However, commercial development has been hindered due to a variety of constraints such as reliability, non-linear behavior, cost of driving electronics, and form factor requirements. This paper presents the systematic development from laboratory concept to commercial readiness of a novel pressure sensing system using a DEAP membrane. The pressure sensing system was designed for in-line pressure measurements for low pressure applications such as health systems monitoring. A first generation sensor was designed, built and tested with a focus on the qualitative capabilities of EAP membranes as sensors. Experimental measurements were conducted that demonstrated the capability of the sensor to output a voltage signal proportional to a changing pressure. Several undesirable characteristics were observed during these initial tests such as strong hysteresis, non-linearity, very limited pressure range, and low fatigue life. A second generation prototype was then designed to remove or compensate for these undesirable characteristics. This prototype was then built and tested. The new design showed an almost complete removal of hysteretic non-linear effects and was capable of operating at 10 × the pressure range of the initial generation. This new design is the framework for a novel DEAP based pressure sensor ready for commercial applications.

  15. Measuring brain activity with magnetoresistive sensors integrated in micromachined probe needles

    NASA Astrophysics Data System (ADS)

    Amaral, José; Gaspar, João; Pinto, Vitor; Costa, Tiago; Sousa, Nuno; Cardoso, Susana; Freitas, Paulo

    2013-05-01

    An alternative neuroscience tool for magnetic field detection is described in this work, providing both micrometer-scale spatial resolution and high sensitivity to detect the extremely small magnetic fields (nT range) induced by the ionic currents flowing within electrically active neurons. The system combines an array of magnetoresistive sensors incorporated on micro-machined Si probes capable of being inserted within the brain current sources. The Si-etch based micromachining process for neural probes is demonstrated in the manufacture of a probe with 15 magnetoresistive sensors in the tip of each shaft. The probe shafts are formed by double-sided deep reactive ion etching on a double-side polished silicon wafer. The shafts typically have the dimensions 1.2 mm × 40 μm × 300 μm and end in chisel-shaped tips with an incorporated magnetoresistive sensor with dimensions of 30 μm × 2 μm. An accompanying interconnect flexible cable is glued and wirebonded enabling precise and flexible positioning of the probes in the neural tissue. Our analyses showed sharply defined probes and probe tips. The electrical and magnetic behavior of the sensors was verified, and a preliminary test with brain slices were performed.

  16. A novel active suppression technology against thermal drift for ultra-precision spherical capacitive sensors

    NASA Astrophysics Data System (ADS)

    Cui, Junning; Lu, Yesheng; Sun, Tao; Ou, Yaodong

    2015-02-01

    In order to solve the problem of thermal drift and further improve the performance for sensors with extreme demand for precision, based on analysis of shortcomings of existing compensation methods and characteristics of thermal drift, a novel active suppression technology against thermal drift is proposed. Considering the change of properties of reference elements in sensors caused by temperature variation is the most major factor that introduces thermal drift error, a special thermal structure is designed to provide a small environmental chamber with sub-structure design of high performance heat isolation, heat conduction and homogenization of temperature, and the temperature in the environmental chamber is controlled with high precision based on bilateral temperature adjusting with thermo electronic cooler (TEC) devices, and a compound control algorithm of Bang-Bang and anti-windup PID. Experimental results with an ultra-precision spherical capacitive sensor show thermal drift error is significantly eliminated and the precision of the sensor can reach the level of several resolutions.

  17. Noncontact accurate measurement of cardiopulmonary activity using a compact quadrature Doppler radar sensor.

    PubMed

    Hu, Wei; Zhao, Zhangyan; Wang, Yunfeng; Zhang, Haiying; Lin, Fujiang

    2014-03-01

    The designed sensor enables accurate reconstruction of chest-wall movement caused by cardiopulmonary activities, and the algorithm enables estimation of respiration, heartbeat rate, and some indicators of heart rate variability (HRV). In particular, quadrature receiver and arctangent demodulation with calibration are introduced for high linearity representation of chest displacement; 24-bit ADCs with oversampling are adopted for radar baseband acquisition to achieve a high signal resolution; continuous-wavelet filter and ensemble empirical mode decomposition (EEMD) based algorithm are applied for cardio/pulmonary signal recovery and separation so that accurate beat-to-beat interval can be acquired in time domain for HRV analysis. In addition, the wireless sensor is realized and integrated on a printed circuit board compactly. The developed sensor system is successfully tested on both simulated target and human subjects. In simulated target experiments, the baseband signal-to-noise ratio (SNR) is 73.27 dB, high enough for heartbeat detection. The demodulated signal has 0.35% mean squared error, indicating high demodulation linearity. In human subject experiments, the relative error of extracted beat-to-beat intervals ranges from 2.53% to 4.83% compared with electrocardiography (ECG) R-R peak intervals. The sensor provides an accurate analysis for heart rate with the accuracy of 100% for p = 2% and higher than 97% for p = 1%. PMID:24235293

  18. The application of machine learning in multi sensor data fusion for activity recognition in mobile device space

    NASA Astrophysics Data System (ADS)

    Marhoubi, Asmaa H.; Saravi, Sara; Edirisinghe, Eran A.

    2015-05-01

    The present generation of mobile handheld devices comes equipped with a large number of sensors. The key sensors include the Ambient Light Sensor, Proximity Sensor, Gyroscope, Compass and the Accelerometer. Many mobile applications are driven based on the readings obtained from either one or two of these sensors. However the presence of multiple-sensors will enable the determination of more detailed activities that are carried out by the user of a mobile device, thus enabling smarter mobile applications to be developed that responds more appropriately to user behavior and device usage. In the proposed research we use recent advances in machine learning to fuse together the data obtained from all key sensors of a mobile device. We investigate the possible use of single and ensemble classifier based approaches to identify a mobile device's behavior in the space it is present. Feature selection algorithms are used to remove non-discriminant features that often lead to poor classifier performance. As the sensor readings are noisy and include a significant proportion of missing values and outliers, we use machine learning based approaches to clean the raw data obtained from the sensors, before use. Based on selected practical case studies, we demonstrate the ability to accurately recognize device behavior based on multi-sensor data fusion.

  19. Recruitment and activation of the ATM kinase in the absence of DNA damage sensors

    PubMed Central

    Hartlerode, Andrea J.; Morgan, Mary J.; Wu, Yipin; Buis, Jeffrey; Ferguson, David O.

    2015-01-01

    Two kinases, ATM and DNA-PKcs, control rapid responses to DNA double-strand breaks (DSBs). The paradigm for ATM control is recruitment and activation by the Mre11–Rad50–NBS1 (MRN) sensor complex, whereas DNA-PKcs requires the sensor Ku (Ku70–Ku80). Using Mus musculus cells harboring targeted mutant alleles of Mre11 and/or Ku70, together with pharmacologic kinase inhibition we demonstrate that ATM can in fact be activated by DSBs in the absence of MRN. When MRN is deficient, DNA-PKcs efficiently substitutes for ATM in facilitating local chromatin responses. Strikingly, in the absence of both MRN and Ku, ATM is recruited to chromatin, phosphorylates H2AX, and triggers the G2/M cell cycle checkpoint, but DNA repair functions of MRN are not restored. This implies that a complex interplay between sensors plays a significant role in ATM control, rather than straightforward recruitment and activation by MRN. PMID:26280532

  20. Development of active edge pixel sensors and four-side buttable modules using vertical integration technologies

    NASA Astrophysics Data System (ADS)

    Macchiolo, A.; Andricek, L.; Moser, H.-G.; Nisius, R.; Richter, R. H.; Terzo, S.; Weigell, P.

    2014-11-01

    We present an R&D activity focused on the development of novel modules for the upgrade of the ATLAS pixel system at the High Luminosity LHC (HL-LHC). The modules consist of n-in-p pixel sensors, 100 or 200 μm thick, produced at VTT (Finland) with an active edge technology, which considerably reduces the dead area at the periphery of the device. The sensors are interconnected with solder bump-bonding to the ATLAS FE-I3 and FE-I4 read-out chips, and characterised with radioactive sources and beam tests at the CERN-SPS and DESY. The results of these measurements will be discussed for devices before and after irradiation up to a fluence of 5 ×1015neq /cm2. We will also report on the R&D activity to obtain Inter Chip Vias (ICVs) on the ATLAS read-out chip in collaboration with the Fraunhofer Institute EMFT. This step is meant to prove the feasibility of the signal transport to the newly created readout pads on the backside of the chips allowing for four side buttable devices without the presently used cantilever for wire bonding. The read-out chips with ICVs will be interconnected to thin pixel sensors, 75 μm and 150 μm thick, with the Solid Liquid Interdiffusion (SLID) technology, which is an alternative to the standard solder bump-bonding.

  1. Wearable motion sensors to continuously measure real-world physical activities

    PubMed Central

    Dobkin, Bruce H.

    2014-01-01

    Purpose of review Rehabilitation for sensorimotor impairments aims to improve daily activities, walking, exercise, and motor skills. Monitoring of practice and measuring outcomes, however, is usually restricted to laboratory-based procedures and self-reports. Mobile health devices may reverse these confounders of daily care and research trials. Recent findings Wearable, wireless motion sensor data, analyzed by activity pattern-recognition algorithms, can describe the type, quantity, and quality of mobility-related activities in the community. Data transmission from sensors to the cell phone and Internet enable continuous monitoring. Remote access to laboratory-quality data about walking speed, duration and distance, gait asymmetry and smoothness of movements, as well as cycling, exercise, and skills practice, opens new opportunities to engage patients in progressive, personalized therapies with feedback about performance. Clinical trial designs will be able to include remote verification of the integrity of complex physical interventions and compliance with practice, as well as capture repeated, ecologically sound, ratio-scale outcome measures. Summary Given the progressively falling cost of miniaturized wearable gyroscopes, accelerometers, and other physiologic sensors, as well as inexpensive data transmission, sensing systems may become as ubiquitous as cell phones for health care. Neurorehabilitation can develop these mobile health platforms for daily care and clinical trials to improve exercise and fitness, skills learning, and physical functioning. PMID:24136126

  2. Sensor evaluation study for use with towed arrays for UXO site characterization

    SciTech Connect

    McDonald, J.R.; Robertson, R.

    1996-11-01

    The Naval Research Laboratory is developing a Multi-sensor Towed Array Detection System (MTADS) with support from the DOD Environmental Security Technology Certification Program (ESTCP). In this effort we seek to extend and refine ordnance detection technology to more efficiently characterize OEW sites, identifying nonferrous and smaller items, distinguishing ordnance from clutter and analyzing clustered targets to identify and locate individual targets within complex target fields. Our evaluation shows that these goals are best met by combining magnetic and electromagnetic sensors. We report on field studies at a prepared test range of commercial sensors in arrays in various configurations and including; Cesium vapor magnetometers in single sensor and gradiometric configurations, fluxgate gradiometers, proton procession magnetometers, and electromagnetic pulsed induction sensors. The advantages and disadvantages of each technology and their applicability based upon survey requirements is discussed. We also discuss recommended data densities including horizontal sensor spacings, survey speeds, sensor heights and make recommendations about the appropriate use of gradiometers and active sensors.

  3. An evaluation of three-dimensional sensors for the extravehicular activity helper/retreiver

    NASA Technical Reports Server (NTRS)

    Magee, Michael

    1993-01-01

    The Extravehicular Activity Retriever/Helper (EVAHR) is a robotic device currently under development at the NASA Johnson Space Center that is designed to fetch objects or to assist in retrieving an astronaut who may have become inadvertently de-tethered. The EVAHR will be required to exhibit a high degree of intelligent autonomous operation and will base much of its reasoning upon information obtained from one or more three-dimensional sensors that it will carry and control. At the highest level of visual cognition and reasoning, the EVAHR will be required to detect objects, recognize them, and estimate their spatial orientation and location. The recognition phase and estimation of spatial pose will depend on the ability of the vision system to reliably extract geometric features of the objects such as whether the surface topologies observed are planar or curved and the spatial relationships between the component surfaces. In order to achieve these tasks, accurate sensing of the operational environment and objects in the environment will therefore be critical. The qualitative and quantitative results of empirical studies of three sensors that are capable of providing three-dimensional information to the EVAHR, but using completely different hardware approaches are documented. The first of these devices is a phase shift laser with an effective operating range (ambiguity interval) of approximately 15 meters. The second sensor is a laser triangulation system designed to operate at much closer range and to provide higher resolution images. The third sensor is a dual camera stereo imaging system from which range images can also be obtained. The remainder of the report characterizes the strengths and weaknesses of each of these systems relative to quality of data extracted and how different object characteristics affect sensor operation.

  4. A Brief Overview of NASA Glenn Research Center Sensor and Electronics Activities

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.

    2012-01-01

    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.

  5. Reflective chamber for hardware-in-the-loop simulation of active/passive millimeter wave sensors

    NASA Astrophysics Data System (ADS)

    Sholes, W. J.; Wilsdorf, T. T.

    A unique reflective chamber has been developed at the MICOM Advanced Simulation Center for hardware-in-the-loop simulation for combined active and passive millimeter sensors. This paper describes the reasons for developing such a reflective chamber and provides results of measurement of active reflection levels and radiometric temperatures within the chamber. Utilization of this chamber in a hardware-in-the-loop simulation for a millimeter wave weapon system is described, including the computer equipment and software system for real-time control of the simulator.

  6. A systematic investigation of SO2 removal dynamics by coal-based activated cokes: The synergic enhancement effect of hierarchical pore configuration and gas components

    NASA Astrophysics Data System (ADS)

    Sun, Fei; Gao, Jihui; Liu, Xin; Tang, Xiaofan; Wu, Shaohua

    2015-12-01

    For the aim to break through the long-term roadblock to porous carbon based SO2 removal technology, typical coal-based activated cokes differing in terms of surface area, pore configuration and surface functional properties, were employed to investigate the SO2 removal dynamics. Among the employed activated cokes, the one with a hierarchically porous structure greatly enhanced the SO2 removal dynamics under the simulated flue gas compositions. More detailedly, SO2 separate adsorption property under normal temperature and pressure evidenced that monolayer SO2 molecules anchoring on micropore surface is the main adsorption pattern. The catalytic oxidation of SO2 follows the Eley-Rideal mechanism by which SO2 was firstly oxidized by molecular oxygen into SO3 which could depart partially to release the active sites for further adsorption. For the role of hierarchical pore configuration, it was proposed that micropores serve as gas adsorption and reaction accommodation, meso-/macropores act as byproduct H2SO4 transport and buffing reservoirs, which may in turn gives rise to the recovery of active sites in micropores and guarantees the continuous proceeding of sulfur-containing species transformation in the micropores. The present results suggest that pore configuration or interconnecting pattern, but not mere surface area or pore volume, should be favourably considered for optimizing heterogeneous gas-solid adsorption and reaction.

  7. Hydra Rendezvous and Docking Sensor

    NASA Technical Reports Server (NTRS)

    Roe, Fred; Carrington, Connie

    2007-01-01

    The U.S. technology to support a CEV AR&D activity is mature and was developed by NASA and supporting industry during an extensive research and development program conducted during the 1990's and early 2000 time frame at the Marshall Space Flight Center. Development and demonstration of a rendezvous/docking sensor was identified early in the AR&D Program as the critical enabling technology that allows automated proxinity operations and docking. A first generation rendezvous/docking sensor, the Video Guidance Sensor (VGS) was developed and successfully flown on STS 87 and again on STS 95, proving the concept of a video-based sensor. Advances in both video and signal processing technologies and the lessons learned from the two successful flight experiments provided a baseline for the development of a new generation of video based rendezvous/docking sensor. The Advanced Video Guidance Sensor (AVGS) has greatly increased performance and additional capability for longer-range operation. A Demonstration Automatic Rendezvous Technology (DART) flight experiment was flown in April 2005 using AVGS as the primary proximity operations sensor. Because of the absence of a docking mechanism on the target satellite, this mission did not demonstrate the ability of the sensor to coltrold ocking. Mission results indicate that the rendezvous sensor operated successfully in "spot mode" (2 km acquisition of the target, bearing data only) but was never commanded to "acquire and track" the docking target. Parts obsolescence issues prevent the construction of current design AVGS units to support the NASA Exploration initiative. This flight proven AR&D technology is being modularized and upgraded with additional capabilities through the Hydra project at the Marshall Space Flight Center. Hydra brings a unique engineering approach and sensor architecture to the table, to solve the continuing issues of parts obsolescence and multiple sensor integration. This paper presents an approach to

  8. Depleted Monolithic Active Pixel Sensors (DMAPS) implemented in LF-150 nm CMOS technology

    NASA Astrophysics Data System (ADS)

    Kishishita, T.; Hemperek, T.; Krüger, H.; Wermes, N.

    2015-03-01

    We present the recent development of Depleted Monolithic Active Pixel Sensors (DMAPS), implemented with an LFoundry (LF) 150 nm CMOS process. MAPS detectors based on an epi-layer have been matured in recent years and have attractive features in terms of reducing material budget and handling cost compared to conventional hybrid pixel detectors. However, the obtained signal is relatively small (~1000 e-) due to the thin epi-layer, and charge collection time is relatively slow, e.g., in the order of 100 ns, because charges are mainly collected by diffusion. Modern commercial CMOS technology, however, offers advanced process options to overcome such difficulties and enable truly monolithic devices as an alternative to hybrid pixel sensors and charge coupled devices. Unlike in the case of the standard MAPS technologies with epi-layers, the LF process provides a high-resistivity substrate that enables large signal and fast charge collection by drift in a ~50 μm thick depleted layer. Since this process also enables the use of deep n- and p-wells to isolate the collection electrode from the thin active device layer, PMOS and NMOS transistors are available for the readout electronics in each pixel cell. In order to evaluate the sensor and transistor characteristics, several collection electrodes variants and readout architectures have been implemented. In this report, we focus on its design aspect of the LF-DMAPS prototype chip.

  9. An active cooperation-aware spectrum allocation mechanism for body sensor networks.

    PubMed

    Jiang, Fu; Guo, Ying; Peng, Jun; Hu, Jiankun

    2015-01-01

    A cognitive radio-based spectrum allocation scheme using an active cooperative-aware mechanism is proposed in this paper. The scheme ensures that the primary user and secondary users cooperate actively for their own benefits. The primary user releases some spectrum resources to secondary users to actively stimulate them to actively join the cooperative transmission of the primary user, and secondary users help the primary user to relay data in return, as well as its self-data transmission at the same time. The Stackelberg game is used to evenly and jointly optimize the utilities of both the primary and secondary users. Simulation results show that the proposed active cooperation-aware mechanism could improve the body sensor network performance. PMID:25635409

  10. An Active Cooperation-Aware Spectrum Allocation Mechanism for Body Sensor Networks

    PubMed Central

    Jiang, Fu; Guo, Ying; Peng, Jun; Hu, Jiankun

    2015-01-01

    A cognitive radio-based spectrum allocation scheme using an active cooperative-aware mechanism is proposed in this paper. The scheme ensures that the primary user and secondary users cooperate actively for their own benefits. The primary user releases some spectrum resources to secondary users to actively stimulate them to actively join the cooperative transmission of the primary user, and secondary users help the primary user to relay data in return, as well as its self-data transmission at the same time. The Stackelberg game is used to evenly and jointly optimize the utilities of both the primary and secondary users. Simulation results show that the proposed active cooperation-aware mechanism could improve the body sensor network performance. PMID:25635409

  11. Image sensor innovations for low light levels with active imaging features

    NASA Astrophysics Data System (ADS)

    Powell, Gareth H.; Fereyre, Pierre

    2015-02-01

    Advances in CMOS imaging enable image capture at lower light levels. Color detection is also possible where human vision becomes less sensitive in night conditions. In daytime conditions, there are a number of climatic conditions such as rain, fog, snow or smoke etc. that render traditional `intelligent' outdoor cameras that perform various forms of detection and identification tasks relatively ineffective. It has been proven that an adapted five transistor pixel CMOS sensor can perform range-gated active imaging that extends considerably the usability of intelligent cameras in the most difficult conditions. This paper discusses advanced state of the art image sensors with embedded features, with emphasis on the everimportant size, weight, power and cost benefits and discusses the new applications that are enabled.

  12. Piezoelectric Wafer Active Sensors in Lamb Wave-Based Structural Health Monitoring

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Giurgiutiu, Victor

    2012-07-01

    Recent advancements in sensors and information technologies have resulted in new methods for structural health monitoring (SHM) of the performance and deterioration of structures. The enabling element is the piezoelectric wafer active sensor (PWAS). This paper presents an introduction to PWAS transducers and their applications in Lamb wave-based SHM. We begin by reviewing the fundamentals of piezoelectric intelligent materials. Then, the mechanism of using PWAS transducers as Lamb wave transmitters and receivers is presented. PWAS interact with the host structure through the shear-lag model. Lamb wave mode tuning can be achieved by judicious combination of PWAS dimensions, frequency value, and Lamb mode characteristics. Finally, use of PWAS Lamb wave SHM for damage detection on plate-like aluminum structures is addressed. Examples of using PWAS phased array scanning, quantitative crack detection with array imaging, and quantitative corrosion detection are given.

  13. Novel sensors to enable closed-loop active clearance control in gas turbine engines

    NASA Astrophysics Data System (ADS)

    Geisheimer, Jonathan; Holst, Tom

    2014-06-01

    Active clearance control within the turbine section of gas turbine engines presents and opportunity within aerospace and industrial applications to improve operating efficiencies and the life of downstream components. Open loop clearance control is currently employed during the development of all new large core aerospace engines; however, the ability to measure the gap between the blades and the case and close down the clearance further presents as opportunity to gain even greater efficiencies. The turbine area is one of the harshest environments for long term placement of a sensor in addition to the extreme accuracy requirements required to enable closed loop clearance control. This paper gives an overview of the challenges of clearance measurements within the turbine as well as discusses the latest developments of a microwave sensor designed for this application.

  14. High-fidelity optical reporting of neuronal electrical activity with an ultrafast fluorescent voltage sensor.

    PubMed

    St-Pierre, François; Marshall, Jesse D; Yang, Ying; Gong, Yiyang; Schnitzer, Mark J; Lin, Michael Z

    2014-06-01

    Accurate optical reporting of electrical activity in genetically defined neuronal populations is a long-standing goal in neuroscience. We developed Accelerated Sensor of Action Potentials 1 (ASAP1), a voltage sensor design in which a circularly permuted green fluorescent protein is inserted in an extracellular loop of a voltage-sensing domain, rendering fluorescence responsive to membrane potential. ASAP1 demonstrated on and off kinetics of ∼ 2 ms, reliably detected single action potentials and subthreshold potential changes, and tracked trains of action potential waveforms up to 200 Hz in single trials. With a favorable combination of brightness, dynamic range and speed, ASAP1 enables continuous monitoring of membrane potential in neurons at kilohertz frame rates using standard epifluorescence microscopy. PMID:24755780

  15. Predicting mountain lion activity using radiocollars equipped with mercury tip-sensors

    USGS Publications Warehouse

    Janis, Michael W.; Clark, Joseph D.; Johnson, Craig

    1999-01-01

    Radiotelemetry collars with tip-sensors have long been used to monitor wildlife activity. However, comparatively few researchers have tested the reliability of the technique on the species being studied. To evaluate the efficacy of using tip-sensors to assess mountain lion (Puma concolor) activity, we radiocollared 2 hand-reared mountain lions and simultaneously recorded their behavior and the associated telemetry signal characteristics. We noted both the number of pulse-rate changes and the percentage of time the transmitter emitted a fast pulse rate (i.e., head up) within sampling intervals ranging from 1-5 minutes. Based on 27 hours of observations, we were able to correctly distinguish between active and inactive behaviors >93% of the time using a logistic regression model. We present several models to predict activity of mountain lions; the selection of which to us would depend on study objectives and logistics. Our results indicate that field protocols that use only pulse-rate changes to indicate activity can lead to significant classification errors.

  16. Rapid and quantitative measuring of telomerase activity using an electrochemiluminescent sensor

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoming; Xing, Da; Zhu, Debin; Jia, Li

    2007-11-01

    Telomerase, a ribonucleoprotein enzyme that adds telomeric repeats to the 3'end of chromosomal DNA for maintaining chromosomal integrity and stability. This strong association of telomerase activity with tumors establishing it is the most widespread cancer marker. A number of assays based on the polymerase chain reaction (PCR) have been developed for the evaluation of telomerase activity. However, those methods require gel electrophoresis and some staining procedures. We developed an electrochemiluminescent (ECL) sensor for the measuring of telomerase activity to overcome these problems such as troublesome post-PCR procedures and semi-quantitative assessment in the conventional method. In this assay 5'-biotinylated telomerase synthesis (TS) primer serve as the substrate for the extension of telomeric repeats under telomerase. The extension products were amplified with this TS primer and a tris-(2'2'-bipyridyl) ruthenium (TBR)-labeled reversed primer. The amplified products was separated and enriched in the surface of electrode by streptavidin-coated magnetic beads, and detected by measuring the ECL signals of the TBR labeled. Measuring telomerase activity use the sensor is easy, sensitive, rapid, and applicable to quantitative analysis, should be clinically useful for the detection and monitoring of telomerase activity.

  17. Electron-correlation effects in enhanced ionization of molecules: A time-dependent generalized-active-space configuration-interaction study

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Bauch, S.; Madsen, L. B.

    2015-12-01

    We numerically study models of H2 and LiH molecules, aligned collinearly with the linear polarization of the external field, to elucidate the possible role of correlation in the enhanced-ionization (EI) phenomena. Correlation is considered at different levels of approximation with the time-dependent generalized-active-space configuration-interaction method. The results of our studies show that enhanced ionization occurs in multielectron molecules and that correlation is important, and they also demonstrate significant deviations between the results of the single-active-electron approximation and more accurate configuration-interaction methods. We further investigate the role of low-lying excited states in the EI phenomena. With the inclusion of correlation we show strong carrier-envelope-phase effects in the enhanced ionization of the asymmetric heteronuclear LiH -like molecule. The correlated calculation shows an intriguing feature of crossover in enhanced ionization with two carrier-envelope phases at critical internuclear separation.

  18. Intelligent error correction method applied on an active pixel sensor based star tracker

    NASA Astrophysics Data System (ADS)

    Schmidt, Uwe

    2005-10-01

    Star trackers are opto-electronic sensors used on-board of satellites for the autonomous inertial attitude determination. During the last years star trackers became more and more important in the field of the attitude and orbit control system (AOCS) sensors. High performance star trackers are based up today on charge coupled device (CCD) optical camera heads. The active pixel sensor (APS) technology, introduced in the early 90-ties, allows now the beneficial replacement of CCD detectors by APS detectors with respect to performance, reliability, power, mass and cost. The company's heritage in star tracker design started in the early 80-ties with the launch of the worldwide first fully autonomous star tracker system ASTRO1 to the Russian MIR space station. Jena-Optronik recently developed an active pixel sensor based autonomous star tracker "ASTRO APS" as successor of the CCD based star tracker product series ASTRO1, ASTRO5, ASTRO10 and ASTRO15. Key features of the APS detector technology are, a true xy-address random access, the multiple windowing read out and the on-chip signal processing including the analogue to digital conversion. These features can be used for robust star tracking at high slew rates and under worse conditions like stray light and solar flare induced single event upsets. A special algorithm have been developed to manage the typical APS detector error contributors like fixed pattern noise (FPN), dark signal non-uniformity (DSNU) and white spots. The algorithm works fully autonomous and adapts to e.g. increasing DSNU and up-coming white spots automatically without ground maintenance or re-calibration. In contrast to conventional correction methods the described algorithm does not need calibration data memory like full image sized calibration data sets. The application of the presented algorithm managing the typical APS detector error contributors is a key element for the design of star trackers for long term satellite applications like

  19. Lessons learned with the Active Phasing Experiment: comparison of four optical phasing sensors on a segmented Very Large Telescope

    NASA Astrophysics Data System (ADS)

    Gonte, F.; Surdej, I.

    The adaptive optics capabilities are strongly limited by the quality of the phasing of the primary mirror of the extremely large telescope. Up to date, the Keck telescopes are the only segmented telescope phased with a quality enabling the application of adaptive optics. The Active Phasing Experiment has been installed at the Namyth focus of the Very Large Telescope Melipal during the last 6 months. Its purpose is to understand and compare different technological concepts for an optical phasing sensor dedicated to the European Extremely Large Telescope. The pupil of the telescope is segmented in 61 hexagonal segments by projecting it on an Active Segmented Mirror. The ASM is controlled by a dual wavenlength interferometer made by Fogale Nanotech with a nanometric precision. The segmented pupil is distributed in parallel to four optical phasing sensors. They are a pyramid sensor, a curvature sensor, a phase filtering sensor and a ShackHartmann sensor. They have been developed respectively by Istituto Nazionale di Astrofisica in Florenze, Instituto Astrofisica Canarias in Tenerife, Laboratoire d'Astrophysique de Marseille and ESO. The global behaviour of the optical phasing sensors will be described and preliminary results of the Active Phasing Experiments obtained on sky will be explained. The extrapolation of the results to the EELT and the potential consequences for the adaptive optics will be given. The Active Phasing Experiment has been financed by the European Union and the European Southern Observatory via the Sixth European Union Framework Program for Research and Technological Development under the contract number 011863.

  20. Evaluation of muscular activity duration in shoulders with rotator cuff tears using inertial sensors and electromyography.

    PubMed

    Duc, Cyntia; Pichonnaz, Claude; Bassin, Jean-Philippe; Farron, Alain; Jolles, Brigitte M; Aminian, Kamiar

    2014-12-01

    Shoulder disorders, including rotator cuff tears, affect the shoulder function and result in adapted muscle activation. Although these adaptations have been studied in controlled conditions, free-living activities have not been investigated. Based on the kinematics measured with inertial sensors and portable electromyography, the objectives of this study were to quantify the duration of the muscular activation in the upper trapezius (UT), medial deltoid (MD) and biceps brachii (BB) during motion and to investigate the effect of rotator cuff tear in laboratory settings and daily conditions. The duration of movements and muscular activations were analysed separately and together using the relative time of activation (T(EMG/mov)). Laboratory measurements showed the parameter's reliability through movement repetitions (ICC > 0.74) and differences in painful shoulders compared with healthy ones (p < 0.05): longer activation for UT; longer activation for MD during abduction and tendency to shorter activation in other movements; shorter activation for BB. In daily conditions, T(EMG/mov) for UT was longer, whereas it was shorter for MD and BB (p < 0.05). Moreover, significant correlations were observed between these parameters and clinical scores. This study thus provides new insights into the rotator cuff tear effect on duration of muscular activation in daily activity. PMID:25390457

  1. Improved Optical Fiber Chemical Sensors

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1994-01-01

    Calculations, based on exact theory of optical fiber, have shown how to increase optical efficiency sensitivity of active-core, step-index-profile optical-fiber fluorosensor. Calculations result of efforts to improve efficiency of optical-fiber chemical sensor of previous concept described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525). Optical fiber chemical detector of enhanced sensitivity made in several configurations. Portion of fluorescence or chemiluminescence generated in core, and launched directly into bound electromagnetic modes that propagate along core to photodetector.

  2. Wireless Sensor Networks Approach

    NASA Technical Reports Server (NTRS)

    Perotti, Jose M.

    2003-01-01

    This viewgraph presentation provides information on hardware and software configurations for a network architecture for sensors. The hardware configuration uses a central station and remote stations. The software configuration uses the 'lost station' software algorithm. The presentation profiles a couple current examples of this network architecture in use.

  3. Software Configuration Management Guidebook

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The growth in cost and importance of software to NASA has caused NASA to address the improvement of software development across the agency. One of the products of this program is a series of guidebooks that define a NASA concept of the assurance processes which are used in software development. The Software Assurance Guidebook, SMAP-GB-A201, issued in September, 1989, provides an overall picture of the concepts and practices of NASA in software assurance. Lower level guidebooks focus on specific activities that fall within the software assurance discipline, and provide more detailed information for the manager and/or practitioner. This is the Software Configuration Management Guidebook which describes software configuration management in a way that is compatible with practices in industry and at NASA Centers. Software configuration management is a key software development process, and is essential for doing software assurance.

  4. Genetically encoded far-red fluorescent sensors for caspase-3 activity.

    PubMed

    Zlobovskaya, Olga A; Sergeeva, Tatiana F; Shirmanova, Marina V; Dudenkova, Varvara V; Sharonov, George V; Zagaynova, Elena V; Lukyanov, Konstantin A

    2016-02-01

    Caspase-3 is a key effector caspase that is activated in both extrinsic and intrinsic pathways of apoptosis. Available fluorescent sensors for caspase-3 activity operate in relatively short wavelength regions and are nonoptimal for multiparameter microscopy and whole-body imaging. In the present work, we developed new genetically encoded sensors for caspase-3 activity possessing the most red-shifted spectra to date. These consist of Förster resonance energy transfer (FRET) pairs in which a far-red fluorescent protein (mKate2 or eqFP650) is connected to the infrared fluorescent protein iRFP through a linker containing the DEVD caspase-3 cleavage site. During staurosporine-induced apoptosis of mammalian cells (HeLa and CT26), both mKate2-DEVD-iRFP and eqFP650-DEVD-iRFP sensors showed a robust response (1.6-fold increase of the donor fluorescence intensity). However, eqFP650-DEVD-iRFP displayed aggregation in some cells. For stably transfected CT26 mKate2-DEVD-iRFP cells, fluorescence lifetime imaging (FLIM) enabled us to detect caspase-3 activation due to the increase of mKate2 donor fluorescence lifetime from 1.45 to 2.05 ns. We took advantage of the strongly red-shifted spectrum of mKate2-DEVD-iRFP to perform simultaneous imaging of EGFP-Bax translocation during apoptosis. We conclude that mKate2-DEVD-iRFP is well-suited for multiparameter imaging and also potentially beneficial for in vivo imaging in animal tissues. PMID:26842350

  5. Detection of Early Morning Daily Activities with Static Home and Wearable Wireless Sensors

    NASA Astrophysics Data System (ADS)

    Ince, Nuri Firat; Min, Cheol-Hong; Tewfik, Ahmed; Vanderpool, David

    2007-12-01

    This paper describes a flexible, cost-effective, wireless in-home activity monitoring system for assisting patients with cognitive impairments due to traumatic brain injury (TBI). The system locates the subject with fixed home sensors and classifies early morning bathroom activities of daily living with a wearable wireless accelerometer. The system extracts time- and frequency-domain features from the accelerometer data and classifies these features with a hybrid classifier that combines Gaussian mixture models and a finite state machine. In particular, the paper establishes that despite similarities between early morning bathroom activities of daily living, it is possible to detect and classify these activities with high accuracy. It also discusses system training and provides data to show that with proper feature selection, accurate detection and classification are possible for any subject with no subject specific training.

  6. Electrochemical DNA sensor-based strategy for sensitive detection of DNA demethylation and DNA demethylase activity.

    PubMed

    Shen, Qingming; Fan, Mengxing; Yang, Yin; Zhang, Hui

    2016-08-31

    DNA demethylation and demethylase activity play important roles in DNA self-repair, and their detection is key to early diagnosis of fatal diseases. Herein, a facile electrochemical DNA (E-DNA) sensor was developed for the sensitive detection of DNA demethylation and demethylase activity based on an enzyme cleavage strategy. The thiol modified hemi-methylated hairpin probe DNA (pDNA) was self-assembled on a Au electrode surface through the formation of AuS bonds. The hemi-methylated pDNA served as the substrate of DNA demethylase (using methyl-CpG-binding domain protein 2 (MBD2) as an example). Following demethylation, the hairpin stem was then recognized and cleaved by BstUI endonuclease. The ferrocene carboxylic acid (FcA)-tagged pDNA strands were released into the buffer solution from the electrode surface, resulting in a significant decrease of electrochemical signal and providing a means to observe DNA demethylation. The activity of DNA demethylase was analyzed in the concentration ranging from 0.5 to 500 ng mL(-1) with a limit of detection as low as 0.17 ng mL(-1). With high specificity and sensitivity, rapid response, and low cost, this simple E-DNA sensor provides a unique platform for the sensitive detection of DNA demethylation, DNA demethylase activity, and related molecular diagnostics and drug screening. PMID:27506345

  7. A multi-mode sensing system for corrosion detection using piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Giurgiutiu, Victor; Pollock, Patrick

    2008-03-01

    As an emerging technology for in-situ damage detection and nondestructive evaluation, structural health monitoring with active sensors (active SHM) plays as a promising candidate for the pipeline inspection and diagnosis. Piezoelectric wafer active sensor (PWAS), as an active sensing device, can be permanently attached to the structure to interrogate it at will and can operate in propagating wave mode or electromechanical impedance mode. Its small size and low cost (about $10 each) make itself a potential and unique technology for in-situ SHM application. The objective of the research in this paper is to develop a permanently installed in-situ "multi-mode" sensing system for the corrosion monitoring and prediction of critical pipeline systems. Such a system is used during in-service period, recording and monitoring the changes of the pipelines over time, such as corrosion, wall thickness, etc. Having the real-time data available, maintenance strategies based on these data can then be developed to ensure a safe and less expensive operation of the pipeline systems. After a detailed review of PWAS SHM methods, including ultrasonic, impedance, and thickness measurement, we introduce the concept of PWAS-based multi-mode sensing approach for corrosion detection in pipelines. Particularly, we investigate the potential for using PWAS waves for in thickness mode experimentally. Finally, experiments are conducted to verify the corrosion detection ability of the PWAS network in both metallic plate and pipe in a laboratory setting. Results show successful corrosion localization in both tests.

  8. Defects in lysosomal maturation facilitate the activation of innate sensors in systemic lupus erythematosus.

    PubMed

    Monteith, Andrew J; Kang, SunAh; Scott, Eric; Hillman, Kai; Rajfur, Zenon; Jacobson, Ken; Costello, M Joseph; Vilen, Barbara J

    2016-04-12

    Defects in clearing apoptotic debris disrupt tissue and immunological homeostasis, leading to autoimmune and inflammatory diseases. Herein, we report that macrophages from lupus-prone MRL/lpr mice have impaired lysosomal maturation, resulting in heightened ROS production and attenuated lysosomal acidification. Impaired lysosomal maturation diminishes the ability of lysosomes to degrade apoptotic debris contained within IgG-immune complexes (IgG-ICs) and promotes recycling and the accumulation of nuclear self-antigens at the membrane 72 h after internalization. Diminished degradation of IgG-ICs prolongs the intracellular residency of nucleic acids, leading to the activation of Toll-like receptors. It also promotes phagosomal membrane permeabilization, allowing dsDNA and IgG to leak into the cytosol and activate AIM2 and TRIM21. Collectively, these events promote the accumulation of nuclear antigens and activate innate sensors that drive IFNα production and heightened cell death. These data identify a previously unidentified defect in lysosomal maturation that provides a mechanism for the chronic activation of intracellular innate sensors in systemic lupus erythematosus. PMID:27035940

  9. Multi-Sensor Fusion for Enhanced Contextual Awareness of Everyday Activities with Ubiquitous Devices

    PubMed Central

    Guiry, John J.; van de Ven, Pepijn; Nelson, John

    2014-01-01

    In this paper, the authors investigate the role that smart devices, including smartphones and smartwatches, can play in identifying activities of daily living. A feasibility study involving N = 10 participants was carried out to evaluate the devices' ability to differentiate between nine everyday activities. The activities examined include walking, running, cycling, standing, sitting, elevator ascents, elevator descents, stair ascents and stair descents. The authors also evaluated the ability of these devices to differentiate indoors from outdoors, with the aim of enhancing contextual awareness. Data from this study was used to train and test five well known machine learning algorithms: C4.5, CART, Naïve Bayes, Multi-Layer Perceptrons and finally Support Vector Machines. Both single and multi-sensor approaches were examined to better understand the role each sensor in the device can play in unobtrusive activity recognition. The authors found overall results to be promising, with some models correctly classifying up to 100% of all instances. PMID:24662406

  10. Heat Transfer Measurements with Surface Mounted Foil-Sensors in an Active Mode: A Comprehensive Review and a New Design

    PubMed Central

    Mocikat, Horst; Herwig, Heinz

    2009-01-01

    A comprehensive review of film-sensors shows that they are primarily operated in a passive mode, i.e. without being actively heated to an extent, whereby they create a heat transfer situation on their own. Only when these sensors are used for wall shear stress measurements, the detection of laminar/turbulent transition, or the measurement of certain flow velocities, they are operated in an active mode, i.e. heated by an electrical current (after an appropriate calibration). In our study we demonstrate how these R(T)-based sensors (temperature dependence of the electrical resistance R) can also be applied in an active mode for heat transfer measurements. These measurements can be made on cold, unheated bodies, provided certain requirements with respect to the flow field are fulfilled. Our new sensors are laminated nickel- and polyimide-foils manufactured with a special technology, which is also described in detail. PMID:22574060

  11. Development of a new catalase activity assay for biological samples using optical CUPRAC sensor

    NASA Astrophysics Data System (ADS)

    Bekdeşer, Burcu; Özyürek, Mustafa; Güçlü, Kubilay; Alkan, Fulya Üstün; Apak, Reşat

    2014-11-01

    A novel catalase activity assay was developed for biological samples (liver and kidney tissue homogenates) using a rapid and low-cost optical sensor-based ‘cupric reducing antioxidant capacity' (CUPRAC) method. The reagent, copper(II)-neocuproine (Cu(II)-Nc) complex, was immobilized onto a cation-exchanger film of Nafion, and the absorbance changes associated with the formation of the highly-colored Cu(I)-Nc chelate as a result of reaction with hydrogen peroxide (H2O2) was measured at 450 nm. When catalase was absent, H2O2 produced the CUPRAC chromophore, whereas catalase, being an effective H2O2 scavenger, completely annihilated the CUPRAC signal due to H2O2. Thus, the CUPRAC absorbance due to H2O2 oxidation concomitant with Cu(I)-Nc formation decreased proportionally with catalase. The developed sensor gave a linear response over a wide concentration range of H2O2 (0.68-78.6 μM). This optical sensor-based method applicable to tissue homogenates proved to be efficient for low hydrogen peroxide concentrations (physiological and nontoxic levels) to which the widely used UV method is not accurately responsive. Thus, conventional problems of the UV method arising from relatively low sensitivity and selectivity, and absorbance disturbance due to gaseous oxygen evolution were overcome. The catalase findings of the proposed method for tissue homogenates were statistically alike with those of HPLC.

  12. Isolation of austroinulin possessing cell cycle inhibition activity from Blumea glomerata and revision of its absolute configuration.

    PubMed

    Ohtsuki, Takashi; Koyano, Takashi; Kowithayakorn, Thaworn; Yamaguchi, Naoto; Ishibashi, Masami

    2004-12-01

    A labdane-diterpene, austroinulin (1), together with several known flavonoids and sesquiterpenes were isolated from leaves of Blumea glomerata (Compositae). Austroinulin (1) and most of the flavonoids showed cytotoxicity against HeLa cells, while austroinulin (1) exhibited a cell cycle inhibition effect at the G1 stage at the concentration of 15.2 microg/mL (47.2 microM). The absolute configuration of 1 was revised as 5S,6R,7S,8S,9R,10R on the basis of the modified Mosher's method. PMID:15643553

  13. An essential role for the intra-oocyte MAPK activity in the NSN-to-SN transition of germinal vesicle chromatin configuration in porcine oocytes.

    PubMed

    Sun, Ming-Ju; Zhu, Shuai; Li, You-Wei; Lin, Juan; Gong, Shuai; Jiao, Guang-Zhong; Chen, Fei; Tan, Jing-He

    2016-01-01

    The mechanisms for the transition from non-surrounded nucleolus (NSN) to surrounded nucleolus (SN) chromatin configuration during oocyte growth/maturation are unclear. By manipulating enzyme activities and measuring important molecules using small-follicle pig oocytes with a high proportion of NSN configuration and an extended germinal vesicle stage in vitro, this study has the first time up-to-date established the essential role for intra-oocyte mitogen-activated protein kinase (MAPK) in the NSN-to-SN transition. Within the oocyte in 1-2 mm follicles, a cAMP decline activates MAPK, which prevents the NSN-to-SN transition by activating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) while inhibiting histone deacetylase (HDAC). In cumulus cells of 1-2 mm follicles, a lower level of estradiol and oocyte-derived paracrine factor (ODPF) reduces natriuretic peptide receptor 2 (NPR2) while enhancing FSH and cAMP actions. FSH elevates cAMP levels, which decreases NPR2 while activating MAPK. MAPK closes the gap junctions, which, together with the NPR2 decrease, reduces cyclic guanosine monophosphate (cGMP) delivery leading to the cAMP decline within oocytes. In 3-6 mm follicles, a higher level of estradiol and ODPF and a FSH shortage initiate a reversion of the above events leading to MAPK inactivation and NSN-to-SN transition within oocytes. PMID:27009903

  14. An essential role for the intra-oocyte MAPK activity in the NSN-to-SN transition of germinal vesicle chromatin configuration in porcine oocytes

    PubMed Central

    Sun, Ming-Ju; Zhu, Shuai; Li, You-Wei; Lin, Juan; Gong, Shuai; Jiao, Guang-Zhong; Chen, Fei; Tan, Jing-He

    2016-01-01

    The mechanisms for the transition from non-surrounded nucleolus (NSN) to surrounded nucleolus (SN) chromatin configuration during oocyte growth/maturation are unclear. By manipulating enzyme activities and measuring important molecules using small-follicle pig oocytes with a high proportion of NSN configuration and an extended germinal vesicle stage in vitro, this study has the first time up-to-date established the essential role for intra-oocyte mitogen-activated protein kinase (MAPK) in the NSN-to-SN transition. Within the oocyte in 1–2 mm follicles, a cAMP decline activates MAPK, which prevents the NSN-to-SN transition by activating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) while inhibiting histone deacetylase (HDAC). In cumulus cells of 1–2 mm follicles, a lower level of estradiol and oocyte-derived paracrine factor (ODPF) reduces natriuretic peptide receptor 2 (NPR2) while enhancing FSH and cAMP actions. FSH elevates cAMP levels, which decreases NPR2 while activating MAPK. MAPK closes the gap junctions, which, together with the NPR2 decrease, reduces cyclic guanosine monophosphate (cGMP) delivery leading to the cAMP decline within oocytes. In 3–6 mm follicles, a higher level of estradiol and ODPF and a FSH shortage initiate a reversion of the above events leading to MAPK inactivation and NSN-to-SN transition within oocytes. PMID:27009903

  15. A 512×512 CMOS Monolithic Active Pixel Sensor with integrated ADCs for space science

    NASA Astrophysics Data System (ADS)

    Prydderch, M. L.; Waltham, N. J.; Turchetta, R.; French, M. J.; Holt, R.; Marshall, A.; Burt, D.; Bell, R.; Pool, P.; Eyles, C.; Mapson-Menard, H.

    2003-10-01

    In the last few years, CMOS sensors have become widely used for consumer applications, but little has been done for scientific instruments. In this paper we present the design and experimental characterisation of a Monolithic Active Pixel Sensor (MAPS) intended for a space science application. The sensor incorporates a 525×525 array of pixels on a 25 μm pitch. Each pixel contains a detector together with three transistors that are used for pixel reset, pixel selection and charge-to-voltage conversion. The detector consists of four n-well/p-substrate diodes combining optimum charge collection and low noise performance. The array readout is column-parallel with adjustable gain column amplifiers and a 10-bit single slope ADC. Data conversion takes place simultaneously for all the 525 pixels in one row. The ADC slope can be adjusted in order to give the best dynamic range for a given brightness of a scene. The digitised data are output on a 10-bit bus at 3 MHz. An on-chip state machine generates all of the control signals needed for the readout. All of the bias currents and voltages are generated on chip by a DAC that is programmable through an I 2C compatible interface. The sensor was designed and fabricated on a standard 0.5 μm CMOS technology. The overall die size is 16.7 mm×19.9 mm including the associated readout electronics and bond pads. Preliminary test results show that the full-scale design works well, meeting the Star Tracker requirements with less than 1-bit noise, good linearity and good optical performance.

  16. Review of in situ fabrication methods of piezoelectric wafer active sensor for sensing and actuation applications

    NASA Astrophysics Data System (ADS)

    Lin, Bin; Giurgiutiu, Victor

    2005-05-01

    Structural health monitoring (SHM) is important for reducing maintenance costs while increasing safety and reliability. Piezoelectric wafer active sensors (PWAS) used in SHM applications are able to detect structural damage using Lamb waves. PWAS are small, lightweight, unobtrusive, and inexpensive. PWAS achieve direct transduction between electric and elastic wave energies. PWAS are essential elements in the Lamb-wave SHM with pitch-catch, pulse-echo, and electromechanical impedance methods. Traditionally, structural integrity tests required attachment of sensors to the material surface. This is often a burdensome and time-consuming task, especially considering the size and magnitude of the surfaces measured (such as aircraft, bridges, structural supports, etc.). In addition, there are critical applications where the rigid piezoceramic wafers cannot conform to curved surfaces. Existing ceramic PWAS, while fairly accurate when attached correctly to the substance, may not provide the long term durability required for SHM. The bonded interface between the PWAS and the structure is often the durability weak link. Better durability may be obtained from a built-in sensor that is incorporated into the material. An in-situ fabricated smart sensor may offer better durability. This paper gives a review of the state of the art on the in-situ fabrication of PWAS using different approaches, such as piezoelectric composite approach; polyvinylidene fluoride (PVDF) approach. It will present the principal fabrication methods and results existing to date. Flexible PVDF PWAS have been studied. They were mounted on a cantilever beam and subjected to free vibration testing. The experimental results of the composite PWAS and PVDF PWAS have been compared with the conventional piezoceramic PWAS. The theoretical and experimental results in this study gave the basic demonstration of the piezoelectricity of composite PWAS and PVDF PWAS.

  17. Integrated application of active controls (IAAC) technology to an advanced subsonic transport project. Conventional baseline configuration study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Characteristics of the U.S. domestic fleet were evaluated to determine the mission characteristics that would have the most impact on U. S. transport fuel use in the future. This resulted in selection of a 197-passenger (plus cargo), about 3710-km (2000 nmi) mission. The existing data base was reviewed and additional analysis was conducted as necessary to complete the technical descriptions. The resulting baseline configuration utilizes a double-lobe, but nearly circular, body with seven-abreast seating. External characteristics feature an 8.71 aspect ratio, 31.5-degree sweep wing, a T-tail empennage, and a dual CF6-6D2, wing-mounted engine arrangement. It provides for 22 LD-2 or 11 LD-3 containers plus bulk cargo in the lower lobe. Passenger/cargo loading, servicing provisions, taxi/takeoff speeds, and field length characteristics are all compatible with accepted airline operations and regulatory provisions. The baseline configuration construction uses conventional aluminum structure except for advanced aluminum alloys and a limited amount of graphite epoxy secondary structure. Modern systems are used, including advanced guidance, navigation, and controls which emphasize application of digital electronics and advanced displays.

  18. Activated transport in the νT=1 exciton condensate at balanced and imbalanced densities measured in drag and counter-flow configuration

    NASA Astrophysics Data System (ADS)

    Wiersma, R. D.; Lok, J. G. S.; Kraus, S.; Dietsche, W.; von Klitzing, K.; Schuh, D.; Bichler, M.; Tranitz, H.-P.; Wegscheider, W.

    2006-08-01

    We observe the total filling factor νT=1 exciton condensate in independently contacted bilayer two-dimensional electron systems in samples with minute tunnel coupling. At balanced electron densities in the layers, we find for both drag and counter-flow current configurations, thermally activated transport with a monotonic increase of the activation energy for d/ℓB<1.65 with activation energies up to 0.4 K. In the imbalanced system the activation energies show a striking asymmetry around the balance point, implying that the gap to charge excitations is considerably different in the separate layers that form the bilayer condensate. This indicates that the measured activation energy is neither the binding energy of the excitons, nor their condensation energy.

  19. Prototype Active Silicon Sensor in 150 nm HR-CMOS technology for ATLAS Inner Detector Upgrade

    NASA Astrophysics Data System (ADS)

    Rymaszewski, P.; Barbero, M.; Breugnon, P.; Godiot, S.; Gonella, L.; Hemperek, T.; Hirono, T.; Hügging, F.; Krüger, H.; Liu, J.; Pangaud, P.; Peric, I.; Rozanov, A.; Wang, A.; Wermes, N.

    2016-02-01

    The LHC Phase-II upgrade will lead to a significant increase in luminosity, which in turn will bring new challenges for the operation of inner tracking detectors. A possible solution is to use active silicon sensors, taking advantage of commercial CMOS technologies. Currently ATLAS R&D programme is qualifying a few commercial technologies in terms of suitability for this task. In this paper a prototype designed in one of them (LFoundry 150 nm process) will be discussed. The chip architecture will be described, including different pixel types incorporated into the design, followed by simulation and measurement results.

  20. Activation of Polymorphonuclear Leukocytes by Candidate Biomaterials for an Implantable Glucose Sensor

    PubMed Central

    Sokolov, Andrey; Hellerud, Bernt Christian; Lambris, John D; Johannessen, Erik A; Mollnes, Tom Eirik

    2011-01-01

    Background Continuous monitoring of glucose by implantable microfabricated devices offers key advantages over current transcutaneous glucose sensors that limit usability due to their obtrusive nature and risk of infection. A successful sensory implant should be biocompatible and retain long-lasting function. Polymorphonuclear leukocytes (PMN) play a key role in the inflammatory system by releasing enzymes, cytokines, and reactive oxygen species, typically as a response to complement activation. The aim of this study was to perform an in vitro analysis of PMN activation as a marker for biocompatibility of materials and to evaluate the role of complement in the activation of PMN. Methods Fifteen candidate materials of an implantable glucose sensor were incubated in lepirudin-anticoagulated whole blood. The cluster of differentiation molecule 11b (CD11b) expression on PMN was analyzed with flow cytometry and the myeloperoxidase (MPO) concentration in plasma was analyzed with enzyme-linked immunosorbent assay. Complement activation was prevented by the C3 inhibitor compstatin or the C5 inhibitor eculizumab. Results Three of the biomaterials (cellulose ester, polyamide reverse osmosis membrane, and polyamide thin film membrane), all belonging to the membrane group, induced a substantial and significant increase in CD11b expression and MPO release. The changes were virtually identical for these two markers. Inhibition of complement with compstatin or eculizumab reduced the CD11b expression and MPO release dose dependently and in most cases back to baseline. The other 12 materials did not induce significant PMN activation. Conclusion Three of the 15 candidate materials triggered PMN activation in a complement-dependent manner and should therefore be avoided for implementation in implantable microsensors. PMID:22226271

  1. Cryogenic High Pressure Sensor Module

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Shams, Qamar A. (Inventor); Powers, William T. (Inventor)

    1999-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  2. Child activity recognition based on cooperative fusion model of a triaxial accelerometer and a barometric pressure sensor.

    PubMed

    Nam, Yunyoung; Park, Jung Wook

    2013-03-01

    This paper presents a child activity recognition approach using a single 3-axis accelerometer and a barometric pressure sensor worn on a waist of the body to prevent child accidents such as unintentional injuries at home. Labeled accelerometer data are collected from children of both sexes up to the age of 16 to 29 months. To recognize daily activities, mean, standard deviation, and slope of time-domain features are calculated over sliding windows. In addition, the FFT analysis is adopted to extract frequency-domain features of the aggregated data, and then energy and correlation of acceleration data are calculated. Child activities are classified into 11 daily activities which are wiggling, rolling, standing still, standing up, sitting down, walking, toddling, crawling, climbing up, climbing down, and stopping. The overall accuracy of activity recognition was 98.43% using only a single- wearable triaxial accelerometer sensor and a barometric pressure sensor with a support vector machine. PMID:24235114

  3. Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

    PubMed

    Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

    2016-08-10

    We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics. PMID:27430635

  4. Active Design Method for the Static Characteristics of a Piezoelectric Six-Axis Force/Torque Sensor

    PubMed Central

    Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

    2014-01-01

    To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active design theory of the piezoelectric six-axis force sensor is established, including a static analytical/mathematical model and numerical simulation model (finite element model). A piezoelectric six-axis force sensor experimental prototype is developed according to the analytical mathematical model and numerical simulation model, and selected static characteristic parameters (including sensitivity, isotropic degree and cross-coupling) are tested using this model with three approaches. The measured results are in agreement with the analytical results from the static-active design method. Therefore, this study has successfully established a foundation for further research into the piezoelectric multi-axis force sensor and an overall design approach based on static characteristics. PMID:24451460

  5. Active design method for the static characteristics of a piezoelectric six-axis force/torque sensor.

    PubMed

    Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

    2014-01-01

    To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active design theory of the piezoelectric six-axis force sensor is established, including a static analytical/mathematical model and numerical simulation model (finite element model). A piezoelectric six-axis force sensor experimental prototype is developed according to the analytical mathematical model and numerical simulation model, and selected static characteristic parameters (including sensitivity, isotropic degree and cross-coupling) are tested using this model with three approaches. The measured results are in agreement with the analytical results from the static-active design method. Therefore, this study has successfully established a foundation for further research into the piezoelectric multi-axis force sensor and an overall design approach based on static characteristics. PMID:24451460

  6. Sensor-derived physical activity parameters can predict future falls in people with dementia

    PubMed Central

    Schwenk, Michael; Hauer, Klaus; Zieschang, Tania; Englert, Stefan; Mohler, Jane; Najafi, Bijan

    2014-01-01

    Background There is a need for simple clinical tools that can objectively assess fall risk in people with dementia. Wearable sensors seem to have potential for fall prediction, however, there has been limited work performed in this important area. Objective To explore the validity of sensor-derived physical activity (PA) parameters for predicting future falls in people with dementia. To compare sensor-based fall risk assessment with conventional fall risk measures. Methods A cohort study of people with confirmed dementia discharged from a geriatric rehabilitation ward. PA was quantified using 24-hour motion-sensor monitoring at the beginning of the study. PA parameters (percentage of walking, standing, sitting, lying; duration of single walking, standing, and sitting bouts) were extracted using specific algorithms. Conventional assessment included performance-based tests (Timed-up-and-go test, Performance-Oriented-Mobility-Assessment, 5-chair stand) and questionnaires (cognition, ADL-status, fear of falling, depression, previous faller). Outcome measures were fallers (at least one fall in the 3-month follow-up period) versus non-fallers. Results Seventy-seven people were included in the study (age 81.8 ± 6.3; community dwelling 88%, institutionalized 12%). Surprisingly, fallers and non-fallers did not differ on any conventional assessment (p= 0.069–0.991), except for ‘previous faller’ (p= 0.006). Interestingly, several PA parameters discriminated between groups. The ‘walking bouts average duration’, ‘longest walking bout duration’ and ‘walking bouts duration variability’ were lower in fallers, compared to non-fallers (p= 0.008–0.027). The ‘standing bouts average duration’ was higher in fallers (p= 0.050). Two variables, ‘walking bouts average duration’ [odds ratio (OR) 0.79, p= 0.012] and ‘previous faller’ [OR 4.44, p= 0.007] were identified as independent predictors for falls. The OR for a ‘walking bouts average duration’ of

  7. Validation and User Evaluation of a Sensor-Based Method for Detecting Mobility-Related Activities in Older Adults

    PubMed Central

    Geraedts, Hilde A. E.; Zijlstra, Wiebren; Van Keeken, Helco G.; Zhang, Wei; Stevens, Martin

    2015-01-01

    Regular physical activity is essential for older adults to stay healthy and independent. However, daily physical activity is generally low among older adults and mainly consists of activities such as standing and shuffling around indoors. Accurate measurement of this low-energy expenditure daily physical activity is crucial for stimulation of activity. The objective of this study was to assess the validity of a necklace-worn sensor-based method for detecting time-on-legs and daily life mobility related postures in older adults. In addition user opinion about the practical use of the sensor was evaluated. Twenty frail and non-frail older adults performed a standardized and free movement protocol in their own home. Results of the sensor-based method were compared to video observation. Sensitivity, specificity and overall agreement of sensor outcomes compared to video observation were calculated. Mobility was assessed based on time-on-legs. Further assessment included the categories standing, sitting, walking and lying. Time-on-legs based sensitivity, specificity and percentage agreement were good to excellent and comparable to laboratory outcomes in other studies. Category-based sensitivity, specificity and overall agreement were moderate to excellent. The necklace-worn sensor is considered an acceptable valid instrument for assessing home-based physical activity based upon time-on-legs in frail and non-frail older adults, but category-based assessment of gait and postures could be further developed. PMID:26361009

  8. Detection of person borne IEDs using multiple cooperative sensors

    NASA Astrophysics Data System (ADS)

    MacIntosh, Scott; Deming, Ross; Hansen, Thorkild; Kishan, Neel; Tang, Ling; Shea, Jing; Lang, Stephen

    2011-06-01

    The use of multiple cooperative sensors for the detection of person borne IEDs is investigated. The purpose of the effort is to evaluate the performance benefits of adding multiple sensor data streams into an aided threat detection algorithm, and a quantitative analysis of which sensor data combinations improve overall detection performance. Testing includes both mannequins and human subjects with simulated suicide bomb devices of various configurations, materials, sizes and metal content. Aided threat recognition algorithms are being developed to test detection performance of individual sensors against combined fused sensors inputs. Sensors investigated include active and passive millimeter wave imaging systems, passive infrared, 3-D profiling sensors and acoustic imaging. The paper describes the experimental set-up and outlines the methodology behind a decision fusion algorithm-based on the concept of a "body model".

  9. A Low-Operating-Power and Flexible Active-Matrix Organic-Transistor Temperature-Sensor Array.

    PubMed

    Ren, Xiaochen; Pei, Ke; Peng, Boyu; Zhang, Zhichao; Wang, Zongrong; Wang, Xinyu; Chan, Paddy K L

    2016-06-01

    An organic flexible temperature-sensor array exhibits great potential in health monitoring and other biomedical applications. The actively addressed 16 × 16 temperature sensor array reaches 100% yield rate and provides 2D temperature information of the objects placed in contact, even if the object has an irregular shape. The current device allows defect predictions of electronic devices, remote sensing of harsh environments, and e-skin applications. PMID:27111745

  10. Wireless patch sensor for remote monitoring of heart rate, respiration, activity, and falls.

    PubMed

    Chan, Alexander M; Selvaraj, Nandakumar; Ferdosi, Nima; Narasimhan, Ravi

    2013-01-01

    Unobtrusive continuous monitoring of important vital signs and activity metrics has the potential to provide remote health monitoring, at-home screening, and rapid notification of critical events such as heart attacks, falls, or respiratory distress. This paper contains validation results of a wireless Bluetooth Low Energy (BLE) patch sensor consisting of two electrocardiography (ECG) electrodes, a microcontroller, a tri-axial accelerometer, and a BLE transceiver. The sensor measures heart rate, heart rate variability (HRV), respiratory rate, posture, steps, and falls and was evaluated on a total of 25 adult participants who performed breathing exercises, activities of daily living (ADLs), various stretches, stationary cycling, walking/running, and simulated falls. Compared to reference devices, the heart rate measurement had a mean absolute error (MAE) of less than 2 bpm, time-domain HRV measurements had an RMS error of less than 15 ms, respiratory rate had an MAE of 1.1 breaths per minute during metronome breathing, posture detection had an accuracy of over 95% in two of the three patch locations, steps were counted with an absolute error of less than 5%, and falls were detected with a sensitivity of 95.2% and specificity of 100%. PMID:24111135

  11. Liquid crystal based sensors monitoring lipase activity: a new rapid and sensitive method for cytotoxicity assays.

    PubMed

    Hussain, Zakir; Zafiu, Christian; Küpcü, Seta; Pivetta, Lucineia; Hollfelder, Nadine; Masutani, Akira; Kilickiran, Pinar; Sinner, Eva-Kathrin

    2014-06-15

    In this work we present liquid crystal (LC) based sensor devices to monitor cell viability. The sensing layer is composed by the LC and a planar monolayer of phospholipids. In the presence of minute traces of phospholipases, which hydrolyze enzymatically phospholipids, the LC-lipid interface is disintegrated. This event causes a change in orientation of the LC, which was followed in a polarized microscope. The lipase activity can be used to measure the cell viability, since members of this enzyme family are released by cells, as they undergo necrosis. The described sensor was used to monitor the presence of the lipases released from three different cell lines, which were either exposed to highly cytotoxic model compounds (sodium azide and paracetamol) or subjected to freeze-thaw cycles to induce cell death by a non-chemical based inducer for apoptosis, such as temperature. Finally, the comparison of lipase activity detected by a state-of-the-art fluorescence assay to the LC based system resulted in the superiority of the LC system concerning incubation time and sensitivity. PMID:24508543

  12. Wearable wireless sensor platform for studying autonomic activity and social behavior in non-human primates.

    PubMed

    Fletcher, Richard Ribón; Amemori, Ken-ichi; Goodwin, Matthew; Graybiel, Ann M

    2012-01-01

    A portable system has been designed to enable remote monitoring of autonomic nervous system output in non-human primates for the purpose of studying neural function related to social behavior over extended periods of time in an ambulatory setting. In contrast to prior systems which only measure heart activity, are restricted to a constrained laboratory setting, or require surgical attachment, our system is comprised of a multi-sensor self-contained wearable vest that can easily be transferred from one subject to another. The vest contains a small detachable low-power electronic sensor module for measuring electrodermal activity (EDA), electrocardiography (ECG), 3-axis acceleration, and temperature. The wireless transmission is implemented using a standard Bluetooth protocol and a mobile phone, which enables freedom of movement for the researcher as well as for the test subject. A custom Android software application was created on the mobile phone for viewing and recording live data as well as creating annotations. Data from up to seven monkeys can be recorded simultaneously using the mobile phone, with the option of real-time upload to a remote web server. Sample data are presented from two rhesus macaque monkeys showing stimulus-induced response in the laboratory as well as long-term ambulatory data collected in a large monkey cage. This system enables new possibilities for studying underlying mechanisms between autonomic brain function and social behavior with connection to human research in areas such as autism, substance abuse, and mood disorders. PMID:23366816

  13. A New Framework for Robust Retrieval and Fusion of Active/Passive Multi-Sensor Precipitation

    NASA Astrophysics Data System (ADS)

    Ebtehaj, M.; Foufoula-Georgiou, E.; Bras, R. L.

    2014-12-01

    This study introduces a new inversion approach for simultaneous retrieval and optimal fusion of multi-sensor passive/active precipitation spaceborne observations relevant to the Global Precipitation Measurement (GPM) constellation of satellites. This approach uses a modern Maximum a Posteriori (MAP) Bayesian estimator and variational principles to obtain a robust estimate of the rainfall profile from multiple sources of observationally- and physically-based a priori generated databases. The MAP estimator makes use of a constrained mixed and -norm regularization that warranties improved stability and reduced estimation error compared to the classic least-squares estimators, often used in the Bayesian rainfall retrieval techniques. We demonstrate the promise of our framework via detailed algorithmic implementation using the passive and active multi-sensor observations provided by the microwave imager (TMI) and precipitation radar (PR) aboard the Tropical Rainfall Measuring Mission (TRMM) satellite. To this end, we simultaneously obtain an observationally-driven retrieval of the entire precipitation profile using the coincidental TMI-PR observations and then optimally combine it with a first guess derived from physically-consistent a priori collected database of the TMI-2A12 operational product. We elucidate the performance of our algorithm for a wide range of storm environments with a specific focus on extreme and light precipitation events over land and coastal areas for hydrologic applications. The results are also validated versus the ground based observations and the standard TRMM products in seasonal and annual timescales.

  14. Colocalization of Sensors Is Sufficient to Activate the DNA Damage Checkpoint in the Absence of Damage

    PubMed Central

    Bonilla, Carla Yaneth; Melo, Justine Amy

    2010-01-01

    Summary Previous work on the DNA damage checkpoint in Saccharomyces cerevisiae has shown that two complexes independently sense DNA lesions: the kinase Mec1-Ddc2 and the PCNA-like 9-1-1 complex. To test whether colocalization of these components is sufficient for checkpoint activation, we fused these checkpoint proteins to the LacI repressor and artificially colocalized these fusions by expressing them in cells harboring Lac operator arrays. We observed Rad53 and Rad9 phosphorylation, Sml1 degradation, and metaphase delay, demonstrating that colocalization of these sensors is sufficient to activate the checkpoint in the absence of DNA damage. Our tethering system allowed us to establish that CDK functions in the checkpoint pathway downstream of damage processing and checkpoint protein recruitment. This CDK dependence is likely, at least in part, through Rad9, since mutation of CDK consensus sites compromised its checkpoint function. PMID:18471973

  15. Active/passive microwave sensor comparison of MIZ-ice concentration estimates. [Marginal Ice Zone (MIZ)

    NASA Technical Reports Server (NTRS)

    Burns, B. A.; Cavalieri, D. J.; Keller, M. R.

    1986-01-01

    Active and passive microwave data collected during the 1984 summer Marginal Ice Zone Experiment in the Fram Strait (MIZEX 84) are used to compare ice concentration estimates derived from synthetic aperture radar (SAR) data to those obtained from passive microwave imagery at several frequencies. The comparison is carried out to evaluate SAR performance against the more established passive microwave technique, and to investigate discrepancies in terms of how ice surface conditions, imaging geometry, and choice of algorithm parameters affect each sensor. Active and passive estimates of ice concentration agree on average to within 12%. Estimates from the multichannel passive microwave data show best agreement with the SAR estimates because the multichannel algorithm effectively accounts for the range in ice floe brightness temperatures observed in the MIZ.

  16. Active sensor/actuator assemblies for vibration damping, compensation, measurement, and testing

    NASA Astrophysics Data System (ADS)

    Ryaboy, Vyacheslav M.; Kasturi, Prakash S.

    2010-04-01

    The vibration control module known as IQ damper had been developed as part of active vibration damping system for optical tables and other precision vibration isolated platforms. The present work describes steps to expand the application of these units to other tasks, namely, (1) dynamic testing of structures and (2) compensation of forced vibration in local areas. The sensor-actuator assembly, including signal conditioning circuits, is designed as a compact dynamically symmetric module with mechanical interface to an optical table. The test data show that the vibration control modules can be used to measure dynamic compliance characteristics of optical tables with precision comparable to that of dedicated vibration measurement systems. Stable concerted work of active vibration control modules compensating forced harmonic vibration is demonstrated experimentally.

  17. Heavy Ion Transient Characterization of a Photobit Hardened-by-Design Active Pixel Sensor Array

    NASA Technical Reports Server (NTRS)

    Marshall, Paul W.; Byers, Wheaton B.; Conger, Christopher; Eid, El-Sayed; Gee, George; Jones, Michael R.; Marshall, Cheryl J.; Reed, Robert; Pickel, Jim; Kniffin, Scott

    2002-01-01

    This paper presents heavy ion data on the single event transient (SET) response of a Photobit active pixel sensor (APS) four quadrant test chip with different radiation tolerant designs in a standard 0.35 micron CMOS process. The physical design techniques of enclosed geometry and P-channel guard rings are used to design the four N-type active photodiode pixels as described in a previous paper. Argon transient measurements on the 256 x 256 chip array as a function of incident angle show a significant variation in the amount of charge collected as well as the charge spreading dependent on the pixel type. The results are correlated with processing and design information provided by Photobit. In addition, there is a large degree of statistical variability between individual ion strikes. No latch-up is observed up to an LET of 106 MeV/mg/sq cm.

  18. Role of the Exposed Polar Facets in the Performance of Thermally and UV Activated ZnO Nanostructured Gas Sensors

    PubMed Central

    2013-01-01

    ZnO nanostructures with different morphologies (nanowires, nanodisks, and nanostars) were synthesized hydrothermally. Gas sensing properties of the as-grown nanostructures were investigated under thermal and UV activation. The performance of the ZnO nanodisk gas sensor was found to be superior to that of other nanostructures (Sg ∼ 3700% to 300 ppm ethanol and response time and recovery time of 8 and 13 s). The enhancement in sensitivity is attributed to the surface polarities of the different structures on the nanoscale. Furthermore, the selectivity of the gas sensors can be achieved by controlling the UV intensity used to activate these sensors. The highest sensitivity value for ethanol, isopropanol, acetone, and toluene are recorded at the optimal UV intensity of 1.6, 2.4, 3.2, and 4 mW/cm2, respectively. Finally, the UV activation mechanism for metal oxide gas sensors is compared with the thermal activation process. The UV activation of analytes based on solution processed ZnO structures pave the way for better quality gas sensors. PMID:24009781

  19. Initial clinical experience with a new dual sensor SSIR pacemaker controlled by body activity and minute ventilation.

    PubMed

    Alt, E; Combs, W; Fotuhi, P; Bambl, E; Wahlstrand, J; Willhaus, R

    1995-08-01

    Fourteen patients were implanted with a single chamber dual sensor pacemaker (Legend Plus) that measures minute ventilation (VE) via variations in impedance between a bipolar lead and the pacemaker case, and activity via a piezoelectric crystal bonded to the pacemaker case. Chronotropic incompetent patients were exercised on a treadmill and a bicycle in dual sensor mode. Activity only indicated pacing rate was measured using a strap-on pacemaker. Both implanted and strap-on pacemakers were adjusted to yield a steady-state pacing rate of 100 beats/min during hall walk. Pacing rate, VE, and oxygen uptake (VO2) were measured continuously. Linear curve fit analysis slopes for plots of VE versus pacing rate during exercise (1.33-1.49) compared favorably to values reported in normals. Peak pacing rates achieved for treadmill and bicycle testing for dual sensor mode were higher than activity mode alone. Slopes of heart rate to VE or VO2 were not significantly different (P < 0.05) for dual sensor mode in contrast to activity alone. In conclusion, the Legend Plus dual sensor rate adaptive pacing therapy delivered pacing rates more proportional to VE and VO2 under different types of exercise than rates indicated by a strap-on pacemaker in activity mode. PMID:7479170

  20. Using the lead vehicle as preview sensor in convoy vehicle active suspension control

    NASA Astrophysics Data System (ADS)

    Rahman, Mustafizur; Rideout, Geoff

    2012-12-01

    Both ride quality and roadholding of actively suspended vehicles can be improved by sensing the road ahead of the vehicle and using this information in a preview controller. Previous applications have used look-ahead sensors mounted on the front bumper to measure terrain beneath. Such sensors are vulnerable, potentially confused by water, snow, or other soft obstacles and offer a fixed preview time. For convoy vehicle applications, this paper proposes using the overall response of the preceding vehicle(s) to generate preview controller information for follower vehicles. A robust observer is used to estimate the states of a quarter-car vehicle model, from which road profile is estimated and passed on to the follower vehicle(s) to generate a preview function. The preview-active suspension, implemented in discrete time using a shift register approach to improve simulation time, reduces sprung mass acceleration and dynamic tyre deflection peaks by more than 50% and 40%, respectively. Terrain can change from one vehicle to the next if a loose obstacle is dislodged, or if the vehicle paths are sufficiently different so that one vehicle misses a discrete road event. The resulting spurious preview information can give suspension performance worse than that of a passive or conventional active system. In this paper, each vehicle can effectively estimate the road profile based on its own state trajectory. By comparing its own road estimate with the preview information, preview errors can be detected and suspension control quickly switched from preview to conventional active control to preserve performance improvements compared to passive suspensions.

  1. A Large-N Mixed Sensor Active + Passive Seismic Array near Sweetwater, TX

    NASA Astrophysics Data System (ADS)

    Barklage, M.; Hollis, D.; Gridley, J. M.; Woodward, R.; Spriggs, N.

    2014-12-01

    A collaborative high-density seismic survey using broadband and short period seismic sensors was conducted March 7 - April 30, 2014 near Sweetwater, TX. The objective of the survey was to use a combination of controlled source shot slices and passive seismic recordings recorded by multiple types of sensors with different bandwidths and sensitivities to image the subsurface. The broadband component of the survey consisted of 25 continuously recording seismic stations comprised of 20 Trillium Compact Posthole sensors from Nanometrics and 5 Polar Trillium 120PHQs from the IRIS/PASSCAL Instrument Center (PIC). The broadband stations also utilized 25 Centaur digitizers from Nanometrics as well as 25 polar quick deploy enclosures from the PIC. The broadband array was designed to maximize horizontal traveling seismic energy for surface wave analysis over the primary target area with sufficient offset for imaging objectives at depth. The short period component of the survey consisted of 2639 receiver locations using Zland nodes from NodalSeismic. The nodes are further divided into 3 sub-arrays: 1) outlier array 2) active source array 3) backbone array. The outlier array consisted of 25 continuously recording nodes distributed around the edge of the survey at a distance of ~5 km from the survey boundary, and provided valuable constraints to passive data analysis techniques at the edge of the survey boundary. The active source patch consisted of densely spaced nodes that were designed to record signals from a Vibroseis source truck for active source reflection processing and imaging. The backbone array consisted of 292 nodes that covered the entirety of the survey area to maximize the value of the passive data analysis. By utilizing continuous recording and smartly designed arrays for measuring local and regional earthquakes we can incorporate velocity information derived from passive data analysis into the active source processing workflow to produce a superior subsurface

  2. A Depth Video Sensor-Based Life-Logging Human Activity Recognition System for Elderly Care in Smart Indoor Environments

    PubMed Central

    Jalal, Ahmad; Kamal, Shaharyar; Kim, Daijin

    2014-01-01

    Recent advancements in depth video sensors technologies have made human activity recognition (HAR) realizable for elderly monitoring applications. Although conventional HAR utilizes RGB video sensors, HAR could be greatly improved with depth video sensors which produce depth or distance information. In this paper, a depth-based life logging HAR system is designed to recognize the daily activities of elderly people and turn these environments into an intelligent living space. Initially, a depth imaging sensor is used to capture depth silhouettes. Based on these silhouettes, human skeletons with joint information are produced which are further used for activity recognition and generating their life logs. The life-logging system is divided into two processes. Firstly, the training system includes data collection using a depth camera, feature extraction and training for each activity via Hidden Markov Models. Secondly, after training, the recognition engine starts to recognize the learned activities and produces life logs. The system was evaluated using life logging features against principal component and independent component features and achieved satisfactory recognition rates against the conventional approaches. Experiments conducted on the smart indoor activity datasets and the MSRDailyActivity3D dataset show promising results. The proposed system is directly applicable to any elderly monitoring system, such as monitoring healthcare problems for elderly people, or examining the indoor activities of people at home, office or hospital. PMID:24991942

  3. Alumina Encapsulated Strain Gage Not Mechanically Attached To The Substrate, Used to Temperature Compensate an Active High Temperature Gage In A Half-Bridge Configuration

    NASA Technical Reports Server (NTRS)

    Piazza, Anthony (Inventor)

    2001-01-01

    A temperature compensation element for a high-temperature strain gage and the method of fabricating the same. Preferably, the element is a "dummy" strain gage not mechanically attached to the substrate. The element is encapsulated in an insulative material and used to compensate an active high-temperature strain gage and wired in a half-bridge configuration. The temperature compensation element and high-temperature strain gage are fabricated using the method of the present invention. This method includes temporarily adhering the element to a heat sink, encapsulated in an insulative material and then removed from the heat sink. Next, the element is either stacked or placed near the active gage. Ideally, the element and the active gage have substantially similar heat transfer and electrical properties.

  4. Chemical sensors

    SciTech Connect

    Janata, J.; Josowicz, M.; DeVaney, D.M. )

    1994-06-15

    This review of chemical sensors contains the following topics of interest: books and reviews; reviews of sensors by their type; fabrication and selectivity; data processing; thermal sensors; mass sensors (fabrication, gas sensors, and liquid sensors); electrochemical sensors (potentiometric sensors, amperometric sensors, and conductometric sensors); and optical sensors (fabrication, liquid sensors, biosensors, and gas sensors). 795 refs., 1 tab.

  5. Mechanistic Analysis of Activation of the Innate Immune Sensor PKR by Bacterial RNA.

    PubMed

    Hull, Chelsea M; Bevilacqua, Philip C

    2015-11-01

    The protein kinase PKR (protein kinase R) is a sensor in innate immunity. PKR autophosphorylates in the presence of double-stranded RNA enabling it to phosphorylate its substrate, eIF2α (eukaryotic initiation factor 2α), halting cellular translation. Classical activators of PKR are long viral double-stranded RNAs, but recently, PKR has been found to be activated by bacterial RNA. However, the features of bacterial RNA that activate PKR are unknown. We studied the Bacillus subtilis trp 5'-UTR (untranslated region), which is an indirect riboswitch with secondary and tertiary RNA structures that regulate gene function. Additionally, the trp 5'-UTR binds a protein, TRAP (tryptophan RNA-binding attenuation protein), which recognizes l-tryptophan. We present the first evidence that multiple structural features in this RNA, which are typical of bacterial RNAs, activate PKR in TRAP-free and TRAP/l-Trp-bound forms. Segments from the 5'-UTR, including the terminator 5'-stem-loop and Shine-Dalgarno blocking hairpins, demonstrated 5'-triphosphate and flanking RNA tail dependence on PKR activation. Disruption of long-distance tertiary interactions in the 5'-UTR led to partial loss in activation, consistent with highly base-paired regions in bacterial RNA activating PKR. One physiological change a bacterial RNA would face in a human cell is a decrease in the concentration of free magnesium. Upon lowering the magnesium concentration to human physiological conditions of 0.5mM, the trp 5'-UTR continued to activate PKR potently. Moreover, total RNA from Escherichia coli, depleted of rRNA, also activated PKR under these ionic conditions. This study demonstrates that PKR can signal the presence of bacterial RNAs under physiological ionic conditions and offers a potential explanation for the apparent absence of riboswitches in the human genome. PMID:26026708

  6. Bacterial Riboswitches and Ribozymes Potently Activate the Human Innate Immune Sensor PKR.

    PubMed

    Hull, Chelsea M; Anmangandla, Ananya; Bevilacqua, Philip C

    2016-04-15

    The innate immune system provides the first line of defense against pathogens through the recognition of nonspecific patterns in RNA to protect the cell in a generalized way. The human RNA-activated protein kinase, PKR, is a dsRNA binding protein and an essential sensor in the innate immune response, which recognizes viral and bacterial pathogens through their RNAs. Upon activation via RNA-dependent autophosphorylation, PKR phosphorylates the eukaryotic initiation factor eIF2α, leading to termination of translation. PKR has a well-characterized role in recognizing viral RNA, where it binds long stretches of double-stranded RNA nonsequence specifically to promote activation; however, the mechanism by which bacterial RNA activates PKR and the mode by which self RNA avoids activating PKR are unknown. We characterized activation of PKR by three functional bacterial RNAs with pseudoknots and extensive tertiary structure: the cyclic di-GMP riboswitch, the glmS riboswitch-ribozyme, and the twister ribozyme, two of which are ligand-activated. These RNAs were found to activate PKR with comparable potency to long dsRNA. Enzymatic structure mapping in the absence and presence of PKR reveals a clear PKR footprint and provides a structural basis for how these bacterial RNAs activate PKR. In the case of the cyclic di-GMP riboswitch and the glmS riboswitch-ribozyme, PKR appears to dimerize on the peripheral double-stranded regions of the native RNA tertiary structure. Overall, these results provide new insights into how PKR acts as an innate immune signaling protein for the presence of bacteria and suggest a reason for the apparent absence of protein-free riboswitches and ribozymes in the human genome. PMID:27011290

  7. Electron configuration and charge state of electrically active Cu, Ag and Au ions in ZnSe

    NASA Astrophysics Data System (ADS)

    Nedeoglo, N. D.; Sirkeli, V. P.; Nedeoglo, D. D.; Laiho, R.; Lähderanta, E.

    2006-08-01

    The Hall effect, electrical conductivity and electron mobility are investigated at temperatures between 55 and 500 K in n-ZnSe crystals doped with Cu, Ag or Au. The presence of a small amount of Cu atoms leads to an inversion of the sign of the Hall coefficient at temperatures above 300 K. Anomalous temperature dependence of the electron mobility is observed in the samples with low Cu concentration (<0.3 at.% in the melt). Different characters of the temperature dependences of kinetic coefficients are found for n-ZnSe doped with Ag and Au. These curves are typical for crystals having several donor levels at different energetic depths. Immediately after doping, silver behaves like a usual compensating acceptor impurity while gold shows amphoteric properties. We propose a model that explains the anomalies of the temperature dependences of the kinetic coefficients in Cu-doped crystals and the lack of the anomalies in Ag-doped and Au-doped crystals. In accordance with this model and our experimental data, copper in n-ZnSe has two charge states, CuZn+ (d10) and CuZn2+ (d9), and two acceptor levels near the valence band. Silver and gold exist in single-charged states AgZn+ and AuZn+ with d10 electron configuration forming single energy levels near the valence band. Au atoms form mainly interstitial Aui donors at low doping concentrations and substitutional AuZn and AuZn-based acceptors at high doping concentrations. Time stimulation of the amphoteric properties of Ag is discussed.

  8. Silicon force sensor

    DOEpatents

    Galambos, Paul C.; Crenshaw, Thomas B.; Nishida, Erik E.; Burnett, Damon J.; Lantz, Jeffrey W.

    2016-07-05

    The various technologies presented herein relate to a sensor for measurement of high forces and/or high load shock rate(s), whereby the sensor utilizes silicon as the sensing element. A plate of Si can have a thinned region formed therein on which can be formed a number of traces operating as a Wheatstone bridge. The brittle Si can be incorporated into a layered structure comprising ductile and/or compliant materials. The sensor can have a washer-like configuration which can be incorporated into a nut and bolt configuration, whereby tightening of the nut and bolt can facilitate application of a compressive preload upon the sensor. Upon application of an impact load on the bolt, the compressive load on the sensor can be reduced (e.g., moves towards zero-load), however the magnitude of the preload can be such that the load on the sensor does not translate to tensile stress being applied to the sensor.

  9. Electrochemical DNA sensor for anthrax toxin activator gene atxA-detection of PCR amplicons.

    PubMed

    Das, Ritu; Goel, Ajay K; Sharma, Mukesh K; Upadhyay, Sanjay

    2015-12-15

    We report the DNA probe functionalized electrochemical genosensor for the detection of Bacillus anthracis, specific towards the regulatory gene atxA. The DNA sensor is fabricated on electrochemically deposited gold nanoparticle on self assembled layer of (3-Mercaptopropyl) trimethoxysilane (MPTS) on GC electrode. DNA hybridization is monitored by differential pulse voltammogram (DPV). The modified GC electrode is characterized by atomic force microscopy (AFM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) method. We also quantified the DNA probe density on electrode surface by the chronocoulometric method. The detection is specific and selective for atxA gene by DNA probe on the electrode surface. No report is available for the detection of B. anthracis by using atxA an anthrax toxin activator gene. In the light of real and complex sample, we have studied the PCR amplicons of 303, 361 and 568 base pairs by using symmetric and asymmetric PCR approaches. The DNA probe of atxA gene efficiently hybridizes with different base pairs of PCR amplicons. The detection limit is found to be 1.0 pM (S/N ratio=3). The results indicate that the DNA sensor is able to detect synthetic target as well as PCR amplicons of different base pairs. PMID:26257186

  10. Performance of Optimized Actuator and Sensor Arrays in an Active Noise Control System

    NASA Technical Reports Server (NTRS)

    Palumbo, D. L.; Padula, S. L.; Lyle, K. H.; Cline, J. H.; Cabell, R. H.

    1996-01-01

    Experiments have been conducted in NASA Langley's Acoustics and Dynamics Laboratory to determine the effectiveness of optimized actuator/sensor architectures and controller algorithms for active control of harmonic interior noise. Tests were conducted in a large scale fuselage model - a composite cylinder which simulates a commuter class aircraft fuselage with three sections of trim panel and a floor. Using an optimization technique based on the component transfer functions, combinations of 4 out of 8 piezoceramic actuators and 8 out of 462 microphone locations were evaluated against predicted performance. A combinatorial optimization technique called tabu search was employed to select the optimum transducer arrays. Three test frequencies represent the cases of a strong acoustic and strong structural response, a weak acoustic and strong structural response and a strong acoustic and weak structural response. Noise reduction was obtained using a Time Averaged/Gradient Descent (TAGD) controller. Results indicate that the optimization technique successfully predicted best and worst case performance. An enhancement of the TAGD control algorithm was also evaluated. The principal components of the actuator/sensor transfer functions were used in the PC-TAGD controller. The principal components are shown to be independent of each other while providing control as effective as the standard TAGD.

  11. Flux Tensor Constrained Geodesic Active Contours with Sensor Fusion for Persistent Object Tracking.

    PubMed

    Bunyak, Filiz; Palaniappan, Kannappan; Nath, Sumit Kumar; Seetharaman, Gunasekaran

    2007-08-01

    This paper makes new contributions in motion detection, object segmentation and trajectory estimation to create a successful object tracking system. A new efficient motion detection algorithm referred to as the flux tensor is used to detect moving objects in infrared video without requiring background modeling or contour extraction. The flux tensor-based motion detector when applied to infrared video is more accurate than thresholding "hot-spots", and is insensitive to shadows as well as illumination changes in the visible channel. In real world monitoring tasks fusing scene information from multiple sensors and sources is a useful core mechanism to deal with complex scenes, lighting conditions and environmental variables. The object segmentation algorithm uses level set-based geodesic active contour evolution that incorporates the fusion of visible color and infrared edge informations in a novel manner. Touching or overlapping objects are further refined during the segmentation process using an appropriate shape-based model. Multiple object tracking using correspondence graphs is extended to handle groups of objects and occlusion events by Kalman filter-based cluster trajectory analysis and watershed segmentation. The proposed object tracking algorithm was successfully tested on several difficult outdoor multispectral videos from stationary sensors and is not confounded by shadows or illumination variations. PMID:19096530

  12. Flux Tensor Constrained Geodesic Active Contours with Sensor Fusion for Persistent Object Tracking

    PubMed Central

    Bunyak, Filiz; Palaniappan, Kannappan; Nath, Sumit Kumar; Seetharaman, Gunasekaran

    2007-01-01

    This paper makes new contributions in motion detection, object segmentation and trajectory estimation to create a successful object tracking system. A new efficient motion detection algorithm referred to as the flux tensor is used to detect moving objects in infrared video without requiring background modeling or contour extraction. The flux tensor-based motion detector when applied to infrared video is more accurate than thresholding ”hot-spots”, and is insensitive to shadows as well as illumination changes in the visible channel. In real world monitoring tasks fusing scene information from multiple sensors and sources is a useful core mechanism to deal with complex scenes, lighting conditions and environmental variables. The object segmentation algorithm uses level set-based geodesic active contour evolution that incorporates the fusion of visible color and infrared edge informations in a novel manner. Touching or overlapping objects are further refined during the segmentation process using an appropriate shape-based model. Multiple object tracking using correspondence graphs is extended to handle groups of objects and occlusion events by Kalman filter-based cluster trajectory analysis and watershed segmentation. The proposed object tracking algorithm was successfully tested on several difficult outdoor multispectral videos from stationary sensors and is not confounded by shadows or illumination variations. PMID:19096530

  13. Performance of Optimized Actuator and Sensor Arrays in an Active Noise Control System

    NASA Technical Reports Server (NTRS)

    Palumbo, D. L.; Padula, S. L.; Lyle, K. H.; Cline, J. H.; Cabell, R. H.

    1996-01-01

    Experiments have been conducted in NASA Langley s Acoustics and Dynamics Laboratory to determine the effectiveness of optimized actuator/sensor architectures and controller algorithms for active control of harmonic interior noise. Tests were conducted in a large scale fuselage model - a composite cylinder which simulates a commuter class aircraft fuselage with three sections of trim panel and a floor. Using an optimization technique based on the component transfer functions, combinations of 4 out of 8 piezoceramic actuators and 8 out of 462 microphone locations were evaluated against predicted performance. A combinatorial optimization technique call tabu search was employed to select the optimum transducer arrays. Three test frequencies represent the cases of a strong acoustic and strong structural response, a weak acoustic and strong structural response and a strong acoustic and weak structural response. Noise reduction was obtained using a Time Averaged/Gradient Descent (TAGD) controller. Results indicate that the optimization technique successfully predicted best and worst case performance. An enhancement of the TAGD control algorithm was also evaluated. The principal components of the actuator/sensor transfer functions were used in the PC-TAGD controller. The principal components are shown to be independent of each other while providing control as effective as the standard TAGD.

  14. Characterization study of an intensified complementary metal-oxide-semiconductor active pixel sensor

    NASA Astrophysics Data System (ADS)

    Griffiths, J. A.; Chen, D.; Turchetta, R.; Royle, G. J.

    2011-03-01

    An intensified CMOS active pixel sensor (APS) has been constructed for operation in low-light-level applications: a high-gain, fast-light decay image intensifier has been coupled via a fiber optic stud to a prototype "VANILLA" APS, developed by the UK based MI3 consortium. The sensor is capable of high frame rates and sparse readout. This paper presents a study of the performance parameters of the intensified VANILLA APS system over a range of image intensifier gain levels when uniformly illuminated with 520 nm green light. Mean-variance analysis shows the APS saturating around 3050 Digital Units (DU), with the maximum variance increasing with increasing image intensifier gain. The system's quantum efficiency varies in an exponential manner from 260 at an intensifier gain of 7.45 × 103 to 1.6 at a gain of 3.93 × 101. The usable dynamic range of the system is 60 dB for intensifier gains below 1.8 × 103, dropping to around 40 dB at high gains. The conclusion is that the system shows suitability for the desired application.

  15. 12-inch-wafer-scale CMOS active-pixel sensor for digital mammography

    NASA Astrophysics Data System (ADS)

    Heo, Sung Kyn; Kosonen, Jari; Hwang, Sung Ha; Kim, Tae Woo; Yun, Seungman; Kim, Ho Kyung

    2011-03-01

    This paper describes the development of an active-pixel sensor (APS) panel, which has a field-of-view of 23.1×17.1 cm and features 70-μm-sized pixels arranged in a 3300×2442 array format, for digital mammographic applications. The APS panel was realized on 12-inch wafers based on the standard complementary metal-oxide-semiconductor (CMOS) technology without physical tiling processes of several small-area sensor arrays. Electrical performance of the developed panel is described in terms of dark current, full-well capacity and leakage current map. For mammographic imaging, the optimized CsI:Tl scintillator is experimentally determined by being combined with the developed panel and analyzing im aging characteristics, such as modulation-transfer function, noise-power spectrum, detective quantum efficiency, image l ag, and contrast-detail analysis by using the CDMAM 3.4 phantom. With these results, we suggest that the developed CMOS-based detector can be used for conventional and advanced digital mammographic applications.

  16. Triboelectric active sensor array for self-powered static and dynamic pressure detection and tactile imaging.

    PubMed

    Lin, Long; Xie, Yannan; Wang, Sihong; Wu, Wenzhuo; Niu, Simiao; Wen, Xiaonan; Wang, Zhong Lin

    2013-09-24

    We report an innovative, large-area, and self-powered pressure mapping approach based on the triboelectric effect, which converts the mechanical stimuli into electrical output signals. The working mechanism of the triboelectric active sensor (TEAS) was theoretically studied by both analytical method and numerical calculation to gain an intuitive understanding of the relationship between the applied pressure and the responsive signals. Relying on the unique pressure response characteristics of the open-circuit voltage and short-circuit current, we realize both static and dynamic pressure sensing on a single device for the first time. A series of comprehensive investigations were carried out to characterize the performance of the TEAS, and high sensitivity (0.31 kPa(-1)), ultrafast response time (<5 ms), long-term stability (30,000 cycles), as well as low detection limit (2.1 Pa) were achieved. The pressure measurement range of the TEAS was adjustable, which means both gentle pressure detection and large-scale pressure sensing were enabled. Through integrating multiple TEAS units into a sensor array, the as-fabricated TEAS matrix was capable of monitoring and mapping the local pressure distribution applied on the device with distinguishable spatial profiles. This work presents a technique for tactile imaging and progress toward practical applications of nanogenerators, providing potential solutions for accomplishment of artificial skin, human-electronic interfacing, and self-powered systems. PMID:23957827

  17. First evidence of phase-contrast imaging with laboratory sources and active pixel sensors

    NASA Astrophysics Data System (ADS)

    Olivo, A.; Arvanitis, C. D.; Bohndiek, S. E.; Clark, A. T.; Prydderch, M.; Turchetta, R.; Speller, R. D.

    2007-11-01

    The aim of the present work is to achieve a first step towards combining the advantages of an innovative X-ray imaging technique—phase-contrast imaging (XPCi)—with those of a new class of sensors, i.e. CMOS-based active pixel sensors (APSs). The advantages of XPCi are well known and include increased image quality and detection of details invisible to conventional techniques, with potential application fields encompassing the medical, biological, industrial and security areas. Vanilla, one of the APSs developed by the MI-3 collaboration (see http://mi3.shef.ac.uk), was thoroughly characterised and an appropriate scintillator was selected to provide X-ray sensitivity. During this process, a set of phase-contrast images of different biological samples was acquired by means of the well-established free-space propagation XPCi technique. The obtained results are very encouraging and are in optimum agreement with the predictions of a simulation recently developed by some of the authors thus further supporting its reliability. This paper presents these preliminary results in detail and discusses in brief both the background to this work and its future developments.

  18. A CMOS Energy Harvesting and Imaging (EHI) Active Pixel Sensor (APS) Imager for Retinal Prosthesis.

    PubMed

    Ay, S U

    2011-12-01

    A CMOS image sensor capable of imaging and energy harvesting on same focal plane is presented for retinal prosthesis. The energy harvesting and imaging (EHI) active pixel sensor (APS) imager was designed, fabricated, and tested in a standard 0.5 μm CMOS process. It has 54 × 50 array of 21 × 21 μm(2) EHI pixels, 10-bit supply boosted (SB) SAR ADC, and charge pump circuits consuming only 14.25 μW from 1.2 V and running at 7.4 frames per second. The supply boosting technique (SBT) is used in an analog signal chain of the EHI imager. Harvested solar energy on focal plane is stored on an off-chip capacitor with the help of a charge pump circuit with better than 70% efficiency. Energy harvesting efficiency of the EHI pixel was measured at different light levels. It was 9.4% while producing 0.41 V open circuit voltage. The EHI imager delivers 3.35 μW of power was delivered to a resistive load at maximum power point operation. The measured pixel array figure of merit (FoM) was 1.32 pW/frame/pixel while imager figure of merit (iFoM) including whole chip power consumption was 696 fJ/pixel/code for the EHI imager. PMID:23852551

  19. Performance of a novel wafer scale CMOS active pixel sensor for bio-medical imaging.

    PubMed

    Esposito, M; Anaxagoras, T; Konstantinidis, A C; Zheng, Y; Speller, R D; Evans, P M; Allinson, N M; Wells, K

    2014-07-01

    Recently CMOS active pixels sensors (APSs) have become a valuable alternative to amorphous silicon and selenium flat panel imagers (FPIs) in bio-medical imaging applications. CMOS APSs can now be scaled up to the standard 20 cm diameter wafer size by means of a reticle stitching block process. However, despite wafer scale CMOS APS being monolithic, sources of non-uniformity of response and regional variations can persist representing a significant challenge for wafer scale sensor response. Non-uniformity of stitched sensors can arise from a number of factors related to the manufacturing process, including variation of amplification, variation between readout components, wafer defects and process variations across the wafer due to manufacturing processes. This paper reports on an investigation into the spatial non-uniformity and regional variations of a wafer scale stitched CMOS APS. For the first time a per-pixel analysis of the electro-optical performance of a wafer CMOS APS is presented, to address inhomogeneity issues arising from the stitching techniques used to manufacture wafer scale sensors. A complete model of the signal generation in the pixel array has been provided and proved capable of accounting for noise and gain variations across the pixel array. This novel analysis leads to readout noise and conversion gain being evaluated at pixel level, stitching block level and in regions of interest, resulting in a coefficient of variation ⩽1.9%. The uniformity of the image quality performance has been further investigated in a typical x-ray application, i.e. mammography, showing a uniformity in terms of CNR among the highest when compared with mammography detectors commonly used in clinical practice. Finally, in order to compare the detection capability of this novel APS with the technology currently used (i.e. FPIs), theoretical evaluation of the detection quantum efficiency (DQE) at zero-frequency has been performed, resulting in a higher DQE for this

  20. Performance of a novel wafer scale CMOS active pixel sensor for bio-medical imaging

    NASA Astrophysics Data System (ADS)

    Esposito, M.; Anaxagoras, T.; Konstantinidis, A. C.; Zheng, Y.; Speller, R. D.; Evans, P. M.; Allinson, N. M.; Wells, K.

    2014-07-01

    Recently CMOS active pixels sensors (APSs) have become a valuable alternative to amorphous silicon and selenium flat panel imagers (FPIs) in bio-medical imaging applications. CMOS APSs can now be scaled up to the standard 20 cm diameter wafer size by means of a reticle stitching block process. However, despite wafer scale CMOS APS being monolithic, sources of non-uniformity of response and regional variations can persist representing a significant challenge for wafer scale sensor response. Non-uniformity of stitched sensors can arise from a number of factors related to the manufacturing process, including variation of amplification, variation between readout components, wafer defects and process variations across the wafer due to manufacturing processes. This paper reports on an investigation into the spatial non-uniformity and regional variations of a wafer scale stitched CMOS APS. For the first time a per-pixel analysis of the electro-optical performance of a wafer CMOS APS is presented, to address inhomogeneity issues arising from the stitching techniques used to manufacture wafer scale sensors. A complete model of the signal generation in the pixel array has been provided and proved capable of accounting for noise and gain variations across the pixel array. This novel analysis leads to readout noise and conversion gain being evaluated at pixel level, stitching block level and in regions of interest, resulting in a coefficient of variation ⩽1.9%. The uniformity of the image quality performance has been further investigated in a typical x-ray application, i.e. mammography, showing a uniformity in terms of CNR among the highest when compared with mammography detectors commonly used in clinical practice. Finally, in order to compare the detection capability of this novel APS with the technology currently used (i.e. FPIs), theoretical evaluation of the detection quantum efficiency (DQE) at zero-frequency has been performed, resulting in a higher DQE for this

  1. CMOS Active-Pixel Image Sensor With Intensity-Driven Readout

    NASA Technical Reports Server (NTRS)

    Langenbacher, Harry T.; Fossum, Eric R.; Kemeny, Sabrina

    1996-01-01

    Proposed complementary metal oxide/semiconductor (CMOS) integrated-circuit image sensor automatically provides readouts from pixels in order of decreasing illumination intensity. Sensor operated in integration mode. Particularly useful in number of image-sensing tasks, including diffractive laser range-finding, three-dimensional imaging, event-driven readout of sparse sensor arrays, and star tracking.

  2. An activity recognition model using inertial sensor nodes in a wireless sensor network for frozen shoulder rehabilitation exercises.

    PubMed

    Lin, Hsueh-Chun; Chiang, Shu-Yin; Lee, Kai; Kan, Yao-Chiang

    2015-01-01

    This paper proposes a model for recognizing motions performed during rehabilitation exercises for frozen shoulder conditions. The model consists of wearable wireless sensor network (WSN) inertial sensor nodes, which were developed for this study, and enables the ubiquitous measurement of bodily motions. The model employs the back propagation neural network (BPNN) algorithm to compute motion data that are formed in the WSN packets; herein, six types of rehabilitation exercises were recognized. The packets sent by each node are converted into six components of acceleration and angular velocity according to three axes. Motor features such as basic acceleration, angular velocity, and derivative tilt angle were input into the training procedure of the BPNN algorithm. In measurements of thirteen volunteers, the accelerations and included angles of nodes were adopted from possible features to demonstrate the procedure. Five exercises involving simple swinging and stretching movements were recognized with an accuracy of 85%-95%; however, the accuracy with which exercises entailing spiral rotations were recognized approximately 60%. Thus, a characteristic space and enveloped spectrum improving derivative features were suggested to enable identifying customized parameters. Finally, a real-time monitoring interface was developed for practical implementation. The proposed model can be applied in ubiquitous healthcare self-management to recognize rehabilitation exercises. PMID:25608218

  3. An Activity Recognition Model Using Inertial Sensor Nodes in a Wireless Sensor Network for Frozen Shoulder Rehabilitation Exercises

    PubMed Central

    Lin, Hsueh-Chun; Chiang, Shu-Yin; Lee, Kai; Kan, Yao-Chiang

    2015-01-01

    This paper proposes a model for recognizing motions performed during rehabilitation exercises for frozen shoulder conditions. The model consists of wearable wireless sensor network (WSN) inertial sensor nodes, which were developed for this study, and enables the ubiquitous measurement of bodily motions. The model employs the back propagation neural network (BPNN) algorithm to compute motion data that are formed in the WSN packets; herein, six types of rehabilitation exercises were recognized. The packets sent by each node are converted into six components of acceleration and angular velocity according to three axes. Motor features such as basic acceleration, angular velocity, and derivative tilt angle were input into the training procedure of the BPNN algorithm. In measurements of thirteen volunteers, the accelerations and included angles of nodes were adopted from possible features to demonstrate the procedure. Five exercises involving simple swinging and stretching movements were recognized with an accuracy of 85%–95%; however, the accuracy with which exercises entailing spiral rotations were recognized approximately 60%. Thus, a characteristic space and enveloped spectrum improving derivative features were suggested to enable identifying customized parameters. Finally, a real-time monitoring interface was developed for practical implementation. The proposed model can be applied in ubiquitous healthcare self-management to recognize rehabilitation exercises. PMID:25608218

  4. Identification of EFHD1 as a novel Ca(2+) sensor for mitoflash activation.

    PubMed

    Hou, Tingting; Jian, Chongshu; Xu, Jiejia; Huang, August Yue; Xi, Jianzhong; Hu, Keping; Wei, Liping; Cheng, Heping; Wang, Xianhua

    2016-05-01

    Mitochondrial flashes (mitoflashes) represent stochastic and discrete mitochondrial events that each comprises a burst of superoxide production accompanied by transient depolarization and matrix alkalinization in a respiratory mitochondrion. While mitochondrial Ca(2+) is shown to be an important regulator of mitoflash activity, little is known about its specific mechanism of action. Here we sought to determine possible molecular players that mediate the Ca(2+) regulation of mitoflashes by screening mitochondrial proteins containing the Ca(2+)-binding motifs. In silico analysis and targeted siRNA screening identified four mitoflash activators (MICU1, EFHD1, SLC25A23, SLC25A25) and one mitoflash inhibitor (LETM1) in terms of their ability to modulate mitoflash response to hyperosmotic stress. In particular, overexpression or down-regulation of EFHD1 enhanced or depressed mitoflash activation, respectively, under various conditions of mitochondrial Ca(2+) elevations. Yet, it did not alter mitochondrial Ca(2+) handling, mitochondrial respiration, or ROS-induced mitoflash production. Further, disruption of the two EF-hand motifs of EFHD1 abolished its potentiating effect on the mitoflash responses. These results indicate that EFHD1 functions as a novel mitochondrial Ca(2+) sensor underlying Ca(2+)-dependent activation of mitoflashes. PMID:26975899

  5. Large segmented UV-optical space telescope using a Hybrid Sensor Active Control (HSAC) architecture

    NASA Astrophysics Data System (ADS)

    Feinberg, Lee D.; Dean, Bruce; Hyde, Tupper; Oegerle, Bill; Bolcar, Matthew R.; Smith, J. Scott

    2009-08-01

    Future large UV-optical space telescopes offer new and exciting windows of scientific parameter space. These telescopes can be placed at L2 and borrow heavily from the James Webb Space Telescope (JWST) heritage. For example, they can have similar deployment schemes, hexagonal mirrors, and use Wavefront Sensing and Control (WFSC) technologies developed for JWST. However, a UV-optical telescope requires a 4x improvement in wavefront quality over JWST to be diffraction-limited at 500 nm. Achieving this tolerance would be difficult using a passive thermal architecture such as the one employed on JWST. To solve this problem, our team has developed a novel Hybrid Sensor Active Control (HSAC) architecture that provides a cost effective approach to building a segmented UV-optical space telescope. In this paper, we show the application of this architecture to the ST-2020 mission concept and summarize the technology development requirements.

  6. Optical behavior and sensor activity of Pb ions incorporated ZnO nanocrystals

    NASA Astrophysics Data System (ADS)

    Kannadasan, N.; Shanmugam, N.; Sathishkumar, K.; Cholan, S.; Ponnguzhali, R.; Viruthagiri, G.

    2015-05-01

    We present the synthesis and characterization of nanocrystalline ZnO doped with Pb in different concentrations. The structural and chemical compositions of the products are characterized by XRD, XPS, EDS and FT-IR spectroscopy. The observed results suggest that Pb ions (Pb2+ and Pb4+) are successfully incorporated into the lattice position of Zn2+ ions in ZnO. The optical properties of the products are studied by UV-Vis and room temperature PL measurements. The PL emission spectra of ZnO:Pb, show the intensity quenching for both the UV and visible emissions. The influence of Pb on controlling the size and morphology of ZnO is studied by FESEM and confirmed by HRTEM. Amperometric response shows that ZnO incorporated with 0.075 M of Pb ions has enhanced sensor activity for H2O2 than the undoped product.

  7. E/M impedance modeling and experimentation for the piezoelectric wafer active sensor

    NASA Astrophysics Data System (ADS)

    Kamas, Tuncay; Giurgiutiu, Victor; Lin, Bin

    2015-11-01

    This study aimed to develop theoretical models to accurately predict the in-plane (longitudinal) and out-of-plane (thickness-wise) modes of the electromechanical impedance spectroscopy (EMIS) of a piezoelectric wafer active sensor (PWAS). Two main electrical assumptions are applied for both in-plane and thickness mode PWAS-EMIS in one-dimensional simplified analytical models. These assumptions are 1) constant electrical field assumption and 2) constant electrical displacement assumption. The analytical models with two assumptions are compared with one another to understand the prediction accuracy of the models in different vibration modes. Coupled field finite element analysis (CF-FEA) is also conducted with 2D PWAS model under stress-free boundary conditions. The simulations of the simplified analytical models for free PWAS-EMIS under these two assumptions are carried out. The analytical models are validated by corresponding finite element simulations as well as experimental measurements.

  8. An Internet-based program for depression using activity and physiological sensors: efficacy, expectations, satisfaction, and ease of use

    PubMed Central

    Botella, Cristina; Mira, Adriana; Moragrega, Inés; García-Palacios, Azucena; Bretón-López, Juana; Castilla, Diana; Riera López del Amo, Antonio; Soler, Carla; Molinari, Guadalupe; Quero, Soledad; Guillén-Botella, Verónica; Miralles, Ignacio; Nebot, Sara; Serrano, Berenice; Majoe, Dennis; Alcañiz, Mariano; Baños, Rosa María

    2016-01-01

    Purpose Computerized cognitive behavioral therapy (CCBT) has been shown to be efficacious. Moreover, CCBT can be enhanced by using physiological and activity sensors, but there is no evidence about the acceptability of all these tools. The objective of this study is to examine the efficacy, expectations, satisfaction, and ease of use of an Internet-based CCBT program for preventing depression, with and without sensors (electroencephalography, electrocardiograhpy ECG, and actigraphy), in a high-risk population (unemployed men). Patients and methods Sixty participants at risk of depression (unemployed men) were randomly assigned to three experimental conditions: 1) intervention program (N=22), 2) intervention program plus sensors (N=19), and 3) control group (N=19). Participants completed depression, anxiety, positive and negative affect, and perceived stress measures. Furthermore, they also completed the measures for expectation, satisfaction, and the ease of use of the program. Results Results showed that the two intervention groups improved significantly more than the control group on the clinical variables, and the improvements were greater in the group that used sensors than in the group that did not use them. Furthermore, participants in both intervention groups scored high on expectations and satisfaction with the CCBT program (with and without sensors). The mean score for usability was 88 out of 100 (standard deviation =12.32). No significant differences were found between groups on any of these variables. Conclusion This is the first study to analyze the efficacy, expectations, satisfaction, and ease of use of an Internet-based program using physiological and activity sensors. These results suggest that an Internet program for depression with or without physiological and activity sensors is effective, satisfactory, and easy to use. PMID:27042067

  9. Environmental exposure tracking sensor

    NASA Astrophysics Data System (ADS)

    Havens, Teresa; Everhart, Joel; McFerran, Jace

    2009-03-01

    Cornerstone Research Group Inc. (CRG) has developed environmental exposure tracking (EET) sensors using shape memory polymer (SMP) to monitor the degradation of perishable items, such as munitions, medicines or foods, by measuring the cumulative exposure to temperature and moisture. SMPs are polymers whose qualities have been altered to give them dynamic shape "memory" properties. Under thermal or moisture stimuli, SMP exhibits a radical change from a rigid thermoset to a highly flexible, elastic state. The dynamic response of the SMP can be tailored to match the degradation profile of the perishable item. SMP-based EET sensors require no digital memory or internal power supply and provide the capability of inexpensive, long-term life cycle monitoring thermal and moisture exposure over time. In a Phase I and II SBIR effort with the Navy, CRG demonstrated the feasibility of SMP-based EET sensor with two material systems. These material systems required different activation stimuli, heat or water vapor pressure. CRG developed the ability to tailor these materials to customize the dynamic response to match various degradation profiles of munitions. CRG optimized and characterized the SMP formulations and sensor design configuration to develop a suite of data from which any degradation profile can be met. CRG's EET sensors are capable of monitoring temperatures from -30 °C to 260 °C. The prototypes monitor cumulative thermal exposure and provide real-time information in a visually readable or a remotely interrogated version. CRG is currently scaling up the manufacture of the sensors for munitions reliability applications with the Navy.

  10. Proof of principle study of the use of a CMOS active pixel sensor for proton radiography

    SciTech Connect

    Seco, Joao; Depauw, Nicolas

    2011-02-15

    Purpose: Proof of principle study of the use of a CMOS active pixel sensor (APS) in producing proton radiographic images using the proton beam at the Massachusetts General Hospital (MGH). Methods: A CMOS APS, previously tested for use in s-ray radiation therapy applications, was used for proton beam radiographic imaging at the MGH. Two different setups were used as a proof of principle that CMOS can be used as proton imaging device: (i) a pen with two metal screws to assess spatial resolution of the CMOS and (ii) a phantom with lung tissue, bone tissue, and water to assess tissue contrast of the CMOS. The sensor was then traversed by a double scattered monoenergetic proton beam at 117 MeV, and the energy deposition inside the detector was recorded to assess its energy response. Conventional x-ray images with similar setup at voltages of 70 kVp and proton images using commercial Gafchromic EBT 2 and Kodak X-Omat V films were also taken for comparison purposes. Results: Images were successfully acquired and compared to x-ray kVp and proton EBT2/X-Omat film images. The spatial resolution of the CMOS detector image is subjectively comparable to the EBT2 and Kodak X-Omat V film images obtained at the same object-detector distance. X-rays have apparent higher spatial resolution than the CMOS. However, further studies with different commercial films using proton beam irradiation demonstrate that the distance of the detector to the object is important to the amount of proton scatter contributing to the proton image. Proton images obtained with films at different distances from the source indicate that proton scatter significantly affects the CMOS image quality. Conclusion: Proton radiographic images were successfully acquired at MGH using a CMOS active pixel sensor detector. The CMOS demonstrated spatial resolution subjectively comparable to films at the same object-detector distance. Further work will be done in order to establish the spatial and energy resolution of the

  11. Demonstration of photon–photon resonance peak enhancement by waveguide configuration modification on active multimode interferometer laser diode

    NASA Astrophysics Data System (ADS)

    Kitano, Takuya; Nasir Uddin, Mohammad; Hong, Bingzhou; Tajima, Akio; Jiang, Haisong; Hamamoto, Kiichi

    2016-08-01

    The recent rapid growth of data traffic is leading to high-speed communication for local areas, such as the fiber-to-the-home service. A semiconductor laser is used for such a purpose; however, there is the difficulty that an even higher frequency response occurs in only carrier-photon resonance. For this reason, it is effective to use a second resonance, such as a photon–photon resonance (PPR), for enhancing the frequency response, and the active multimode interferometer laser diode (active-MMI LD) is one of the candidates for achieving a high PPR frequency. In order to obtain an even higher PPR frequency, we have investigated the control scheme of enhancing PPR. In this work, we compared two types of active-MMI waveguide structures to confirm the scheme. As a result, a 3.8 GHz enhancement of the PPR peak, resulting in a 3 dB lower frequency response of 17 GHz, has been successfully achieved by waveguide geometry modification.

  12. Fiber Bragg grating-based sensor for monitoring respiration and heart activity during magnetic resonance imaging examinations

    NASA Astrophysics Data System (ADS)

    Dziuda, Łukasz; Skibniewski, Franciszek W.; Krej, Mariusz; Baran, Paulina M.

    2013-05-01

    We present a fiber-optic sensor for monitoring respiration and heart activity designed to operate in the magnetic resonance imaging (MRI) environment. The sensor employs a Plexiglas springboard, which converts movements of the patient's body lying on the board (i.e., lung- and heart-induced vibrations) to strain, where a fiber Bragg grating attached to the board is used to measure this strain. Experimental studies are carried out during thoracic spine MRI examinations. The presence of the metal-free sensor construction in the MRI environment does not pose a threat to the patient and has no influence over the quality of imaging, and the signal is identical to that obtained without any electromagnetic interference. The results show that the sensor is able to accurately reflect the ballistocardiographic signal, enabling determinations of the respiration rate (RR) and heart rate (HR). The data delivered by the sensor are normally distributed on the Bland-Altman plot for the characteristic point determination and exhibit clear dependence on the RR and HR values for the RR and HR determinations, respectively. Measurement accuracies are better than 7% of the average values, and thus, with further development, the sensor will be implemented in routine MRI examinations.

  13. Highly sensitive multi-layer pressure sensor with an active nanostructured layer of an organic molecular metal

    NASA Astrophysics Data System (ADS)

    Laukhin, V.; Lebedev, V.; Laukhina, E.; Rovira, C.; Veciana, J.

    2016-03-01

    This work addresses to the modern technologies that need to be instrumented with lightweight highly sensitive pressure sensors. The paper presents the development of a new plain flexible thin pressure sensor using a nanostructured layer of the highly sensitive organic piezoresistive metal β-(BEDT-TTF)2I3 as an active component; BEDT-TTF=bis (ethylenedithio)tetrathiafulvalene. The original construction approach permits one to operate the developed sensor on the principle of electrical resistance variations when its piezoresistive layer is elongated under a pressure increase. The pressure sensing element and a set of gold electrodes were integrated into one compact multi-layer design. The construction was optimized to enable one generic design for pressure ranges from 1 to 400 bar. The pressure tests showed that the sensor is able to control a small pressure change as a well definite electrical signal. So the developed type of the sensors is very attractive as a new generation of compact, lightweight, low-cost sensors that might monitor pressure with a good level of measurement accuracy.

  14. Aquarius main structure configuration

    NASA Astrophysics Data System (ADS)

    Eremenko, A.

    The Aquarius/SAC-D Observatory is a joint US-Argentine mission to map the salinity at the ocean surface. This information is critical to improving our understanding of two major components of Earth's climate system - the water cycle and ocean circulation. By measuring ocean salinity from space, the Aquarius/SAC-D Mission will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Aquarius is the primary instrument on the SAC-D spacecraft. It consists of a Passive Microwave Radiometer to detect the surface emission that is used to obtain salinity and an Active Scatterometer to measure the ocean waves that affect the precision of the salinity measurement. The Aquarius Primary Structure houses instrument electronics, feed assemblies, and supports a deployable boom with a 2.5 m Reflector, and provides the structural interface to the SAC-D Spacecraft. The key challenge for the Aquarius main structure configuration is to satisfy the needs of component accommodations, ensuring that the instrument can meet all operational, pointing, environmental, and launch vehicle requirements. This paper describes the evolution of the Aquarius main structure configuration, the challenges of balancing the conflicting requirements, and the major configuration driving decisions and compromises.

  15. Estimating Physical Activity Energy Expenditure with the Kinect Sensor in an Exergaming Environment

    PubMed Central

    Nathan, David; Huynh, Du Q.; Rubenson, Jonas; Rosenberg, Michael

    2015-01-01

    Active video games that require physical exertion during game play have been shown to confer health benefits. Typically, energy expended during game play is measured using devices attached to players, such as accelerometers, or portable gas analyzers. Since 2010, active video gaming technology incorporates marker-less motion capture devices to simulate human movement into game play. Using the Kinect Sensor and Microsoft SDK this research aimed to estimate the mechanical work performed by the human body and estimate subsequent metabolic energy using predictive algorithmic models. Nineteen University students participated in a repeated measures experiment performing four fundamental movements (arm swings, standing jumps, body-weight squats, and jumping jacks). Metabolic energy was captured using a Cortex Metamax 3B automated gas analysis system with mechanical movement captured by the combined motion data from two Kinect cameras. Estimations of the body segment properties, such as segment mass, length, centre of mass position, and radius of gyration, were calculated from the Zatsiorsky-Seluyanov's equations of de Leva, with adjustment made for posture cost. GPML toolbox implementation of the Gaussian Process Regression, a locally weighted k-Nearest Neighbour Regression, and a linear regression technique were evaluated for their performance on predicting the metabolic cost from new feature vectors. The experimental results show that Gaussian Process Regression outperformed the other two techniques by a small margin. This study demonstrated that physical activity energy expenditure during exercise, using the Kinect camera as a motion capture system, can be estimated from segmental mechanical work. Estimates for high-energy activities, such as standing jumps and jumping jacks, can be made accurately, but for low-energy activities, such as squatting, the posture of static poses should be considered as a contributing factor. When translated into the active video gaming

  16. Estimating physical activity energy expenditure with the Kinect Sensor in an exergaming environment.

    PubMed

    Nathan, David; Huynh, Du Q; Rubenson, Jonas; Rosenberg, Michael

    2015-01-01

    Active video games that require physical exertion during game play have been shown to confer health benefits. Typically, energy expended during game play is measured using devices attached to players, such as accelerometers, or portable gas analyzers. Since 2010, active video gaming technology incorporates marker-less motion capture devices to simulate human movement into game play. Using the Kinect Sensor and Microsoft SDK this research aimed to estimate the mechanical work performed by the human body and estimate subsequent metabolic energy using predictive algorithmic models. Nineteen University students participated in a repeated measures experiment performing four fundamental movements (arm swings, standing jumps, body-weight squats, and jumping jacks). Metabolic energy was captured using a Cortex Metamax 3B automated gas analysis system with mechanical movement captured by the combined motion data from two Kinect cameras. Estimations of the body segment properties, such as segment mass, length, centre of mass position, and radius of gyration, were calculated from the Zatsiorsky-Seluyanov's equations of de Leva, with adjustment made for posture cost. GPML toolbox implementation of the Gaussian Process Regression, a locally weighted k-Nearest Neighbour Regression, and a linear regression technique were evaluated for their performance on predicting the metabolic cost from new feature vectors. The experimental results show that Gaussian Process Regression outperformed the other two techniques by a small margin. This study demonstrated that physical activity energy expenditure during exercise, using the Kinect camera as a motion capture system, can be estimated from segmental mechanical work. Estimates for high-energy activities, such as standing jumps and jumping jacks, can be made accurately, but for low-energy activities, such as squatting, the posture of static poses should be considered as a contributing factor. When translated into the active video gaming

  17. Estimation of dynamic metabolic activity in micro-tissue cultures from sensor recordings with an FEM model.

    PubMed

    Pfister, Cornelia; Forstmeier, Christian; Biedermann, Johannes; Schermuly, Julia; Demmel, Franz; Wolf, Peter; Kaspers, Bernd; Brischwein, Martin

    2016-05-01

    We estimated the dynamic cell metabolic activity and the distribution of the pH value and oxygen concentration in tissue samples cultured in vitro by using real-time sensor records and a numerical simulation of the underlying reaction-diffusion processes. As an experimental tissue model, we used chicken spleen slices. A finite element method model representing the biochemical processes and including the relevant sensor data was set up. By fitting the calculated results to the measured data, we derived the spatiotemporal values of the pH value, the oxygen concentration and the absolute metabolic activity (extracellular acidification and oxygen uptake rate) of the samples. Notably, the location of the samples in relation to the sensors has a great influence on the detectable metabolic rates. The long-term vitality of the tissue samples strongly depends on their size. We further discuss the benefits and limitations of the model. PMID:26296800

  18. Unique Activity-Meter with Piezoelectric Poly(vinylidene difluoride) Films and Self Weight of the Sensor Nodes

    NASA Astrophysics Data System (ADS)

    Nogami, Hirofumi; Okada, Hironao; Takamatsu, Seiichi; Kobayashi, Takeshi; Maeda, Ryutaro; Itoh, Toshihiro

    2013-09-01

    We have developed piezoelectric switches for application in ultra low-power wireless sensor nodes to monitor the health condition of chickens. Using Pb(Zr0.52,Ti0.48)O3 (PZT) thin films, we have developed S-shaped PZT cantilevers with proof masses. Since the resonant frequency of PZT devices is approximately 24 Hz, we have utilized their superharmonic resonance to detect chicken movements with frequencies as low as 5-15 Hz. By attaching sensor nodes to chickens, we successfully measured the activity of chickens. However, the PZT devices of other sensor nodes broke down. S-shaped PZT devices are adequate for low vibrations, but are beset by the structural problems of fragmentation upon impact. To address these problems, we examine a method of utilizing poly(vinylidene difluoride) (PVDF) films, which are tough and generate high piezoelectric output voltages under a large stress, as piezoelectric switches. We suggest that the self-weight of sensor nodes be used as the mass of the cantilevers of the PVDF films. One end of a PVDF film is fixed to the case of a sensor node, and the other end is attached to the sensor node. Since PVDF films are subjected to force generated by the self-weight of sensor nodes, high output voltages are expected. A result of measuring output voltages, we confirm the output voltages to be approximately the same as those of PZT devices below 15 Hz at 0.5 m/s2 vibration, which is close to chicken movements. Thus, we consider that we have successfully fabricated a tough wireless sensor node for chickens, utilizing the features of PVDF films.

  19. Detection of (In)activity Periods in Human Body Motion Using Inertial Sensors: A Comparative Study

    PubMed Central

    Olivares, Alberto; Ramírez, Javier; Górriz, Juan M.; Olivares, Gonzalo; Damas, Miguel

    2012-01-01

    Determination of (in)activity periods when monitoring human body motion is a mandatory preprocessing step in all human inertial navigation and position analysis applications. Distinction of (in)activity needs to be established in order to allow the system to recompute the calibration parameters of the inertial sensors as well as the Zero Velocity Updates (ZUPT) of inertial navigation. The periodical recomputation of these parameters allows the application to maintain a constant degree of precision. This work presents a comparative study among different well known inertial magnitude-based detectors and proposes a new approach by applying spectrum-based detectors and memory-based detectors. A robust statistical comparison is carried out by the use of an accelerometer and angular rate signal synthesizer that mimics the output of accelerometers and gyroscopes when subjects are performing basic activities of daily life. Theoretical results are verified by testing the algorithms over signals gathered using an Inertial Measurement Unit (IMU). Detection accuracy rates of up to 97% are achieved. PMID:22778613

  20. Sensor Monitoring of Physical Activity to Improve Glucose Management in Diabetic Patients: A Review

    PubMed Central

    Ding, Sandrine; Schumacher, Michael

    2016-01-01

    Diabetic individuals need to tightly control their blood glucose concentration. Several methods have been developed for this purpose, such as the finger-prick or continuous glucose monitoring systems (CGMs). However, these methods present the disadvantage of being invasive. Moreover, CGMs have limited accuracy, notably to detect hypoglycemia. It is also known that physical exercise, and even daily activity, disrupt glucose dynamics and can generate problems with blood glucose regulation during and after exercise. In order to deal with these challenges, devices for monitoring patients’ physical activity are currently under development. This review focuses on non-invasive sensors using physiological parameters related to physical exercise that were used to improve glucose monitoring in type 1 diabetes (T1DM) patients. These devices are promising for diabetes management. Indeed they permit to estimate glucose concentration either based solely on physical activity parameters or in conjunction with CGM or non-invasive CGM (NI-CGM) systems. In these last cases, the vital signals are used to modulate glucose estimations provided by the CGM and NI-CGM devices. Finally, this review indicates possible limitations of these new biosensors and outlines directions for future technologic developments. PMID:27120602

  1. Implementation of Human-Machine Synchronization Control for Active Rehabilitation Using an Inertia Sensor

    PubMed Central

    Song, Zhibin; Guo, Shuxiang; Xiao, Nan; Gao, Baofeng; Shi, Liwei

    2012-01-01

    According to neuro-rehabilitation practice, active training is effective for mild stroke patients, which means these patients are able to recovery effective when they perform the training to overcome certain resistance by themselves. Therefore, for rehabilitation devices without backdrivability, implementation of human-machine synchronization is important and a precondition to perform active training. In this paper, a method to implement this precondition is proposed and applied in a user’s performance of elbow flexions and extensions when he wore an upper limb exoskeleton rehabilitation device (ULERD), which is portable, wearable and non-backdrivable. In this method, an inertia sensor is adapted to detect the motion of the user’s forearm. In order to get a smooth value of the velocity of the user’s forearm, an adaptive weighted average filtering is applied. On the other hand, to obtain accurate tracking performance, a double close-loop control is proposed to realize real-time and stable tracking. Experiments have been conducted to prove that these methods are effective and feasible for active rehabilitation. PMID:23443366

  2. The heliospheric sheet configuration according to the coronal ray synoptic maps in solar activity cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Guseva, S. A.; Fat'yanov, M. P.; Shramko, A. D.

    2015-05-01

    Two catalogs of coronal ray synoptic maps for different altitudes (1.5-5 R ⊙) for solar activity cycles 23 and 24 (1996-2013) were compiled based on a proposed technique with the data from the SOHO space observatory LASCO C2 coronograph and the Mauna-Loa observatory Mark-IV K coronometer. The constructed synoptic maps of coronal rays represent an image of three-dimensional spherical sections of the heliospheric neutral sheet expanded along the heliographic longitude. The evolution of different heliospheric sheet spatial parameters during the analyzed period was studied based on the obtained maps.

  3. The convergence of complete active space self-consistent-field configuration interaction including all single and double excitation energies to the complete basis set limit.

    PubMed

    Petersson, George A; Malick, David K; Frisch, Michael J; Braunstein, Matthew

    2006-07-28

    Examination of the convergence of full valence complete active space self-consistent-field configuration interaction including all single and double excitation (CASSCF-CISD) energies with expansion of the one-electron basis set reveals a pattern very similar to the convergence of single determinant energies. Calculations on the lowest four singlet states and the lowest four triplet states of N(2) with the sequence of n-tuple-zeta augmented polarized (nZaP) basis sets (n=2, 3, 4, 5, and 6) are used to establish the complete basis set limits. Full configuration-interaction (CI) and core electron contributions must be included for very accurate potential energy surfaces. However, a simple extrapolation scheme that has no adjustable parameters and requires nothing more demanding than CAS(10e(-),8orb)-CISD/3ZaP calculations gives the R(e), omega(e), omega(e)X(e), T(e), and D(e) for these eight states with rms errors of 0.0006 Angstrom, 4.43 cm(-1), 0.35 cm(-1), 0.063 eV, and 0.018 eV, respectively. PMID:16942134

  4. Experimental and CFD simulation studies of wall shear stress for different impeller configurations and MBR activated sludge.

    PubMed

    Ratkovich, N; Chan, C C V; Bentzen, T R; Rasmussen, M R

    2012-01-01

    Membrane bioreactors (MBRs) have been used successfully in biological wastewater treatment for effective solids-liquid separation. However, a common problem encountered with MBR systems is fouling of the membrane resulting in frequent membrane cleaning and replacement which makes the system less appealing for full-scale applications. It has been widely demonstrated that the filtration performances in MBRs can be improved by understanding the shear stress over the membrane surface. Modern tools such as computational fluid dynamics (CFD) can be used to diagnose and understand the shear stress in an MBR. Nevertheless, proper experimental validation is required to validate CFD simulation. In this work experimental measurements of shear stress induced by impellers at a membrane surface were made with an electrochemical approach and the results were used to validate CFD simulations. As good results were obtained with the CFD model (<9% error), it was extrapolated to include the non-Newtonian behaviour of activated sludge. PMID:22592479

  5. Design of an osmotic pressure sensor for sensing an osmotically active substance

    NASA Astrophysics Data System (ADS)

    Ch, Nagesh; Paily, Roy P.

    2015-04-01

    A pressure sensor based on the osmosis principle has been designed and demonstrated successfully for the sensing of the concentration levels of an osmotically active substance. The device is fabricated using the bulk micro-machining technique on a silicon on insulator (SOI) substrate. The substrate has a square cavity on the bottom side to fill with the reference glucose solution and a silicon (Si) membrane on the top side for the actuation. Two sets of devices, having membrane thicknesses of 10 µm and 25 µm, but the same area of 3 mm ×3 mm, are fabricated. The cavity is filled with a glucose solution of 100 mg dL-1 and it is sealed with a semi-permeable membrane made up of cellulose acetate material. The glucose solution is employed to prove the functionality of the device and it is tested for different glucose concentration levels, ranging from 50 mg dL-1 to 450 mg dL-1. The output voltage obtained for the corresponding glucose concentration levels ranges from -6.7 mV to 22.7 mV for the 10 µm device and from -1.7 mV to 4 mV for the 25 µm device. The device operation was simulated using the finite element method (FEM) and the finite volume method (FVM), and the simulation and experimental results match closely. A response time of 40 min is obtained in the case of the 10 µm device compared to one of 30 min for the 25 µm device. The response times obtained for these devices are found to be small compared to those in similar works based on the osmosis principle. This pressure sensor has the potential to provide controlled drug delivery if it can be integrated with other microfluidic devices.

  6. Chemical sensors

    SciTech Connect

    Hubbard, C.W.; Gordon, R.L.

    1987-05-01

    The revolution in analytical chemistry promised by recent developments in the field of chemical sensors has potential for significant positive impact on both research and production activities conducted by and for the Department of Energy. Analyses which were, in the past, performed only with a roomful of expensive equipment can now be performed with miniature solid-state electronic devices or small optical probes. Progress in the development of chemical sensors has been rapid, and the field is currently growing at a great rate. In accordance, Pacific Northwest Laboratory initiated a survey of recent literature so that contributors to active programs in research on analytical methods could be made aware of principles and applications of this new technology. This report presents the results of that survey. The sensors discussed here are divided into three types: micro solid-state devices, optical sensors, and piezoelectric crystal devices. The report is divided into three corresponding sections. The first section, ''Micro Solid-State Devices,'' discusses the design, operation, and application of electronic sensors that are produced in much the same way as standard solid-state electronic devices. The second section, ''Optrodes,'' covers the design and operation of chemical sensors that use fiber optics to detect chemically induced changes in optical properties. The final section, ''Piezoelectric Crystal Detectors,'' discusses two types of chemical sensors that depend on the changes in the properties of an oscillating piezoelectric crystal to detect the presence of certain materials. Advantages and disadvantages of each type of sensor are summarized in each section.

  7. Context based configuration management system

    NASA Technical Reports Server (NTRS)

    Gawdiak, Yuri O. (Inventor); Gurram, Mohana M. (Inventor); Maluf, David A. (Inventor); Mederos, Luis A. (Inventor)

    2010-01-01

    A computer-based system for configuring and displaying information on changes in, and present status of, a collection of events associated with a project. Classes of icons for decision events, configurations and feedback mechanisms, and time lines (sequential and/or simultaneous) for related events are displayed. Metadata for each icon in each class is displayed by choosing and activating the corresponding icon. Access control (viewing, reading, writing, editing, deleting, etc.) is optionally imposed for metadata and other displayed information.

  8. Identifying Activity Levels and Steps in People with Stroke using a Novel Shoe-Based Sensor

    PubMed Central

    Fulk, George D.; Edgar, S. Ryan; Bierwirth, Rebecca; Hart, Phil; Lopez-Meyer, Paulo; Sazonov, Edward

    2012-01-01

    Background/Purpose Advances in sensory technologies provides a method to accurately assess activity levels of people with stroke in their community. This information could be used to determine the effectiveness of rehabilitation interventions as well as provide behavioral enhancing feedback. The purpose of this study was to assess the accuracy of a novel shoe-based sensor system (SmartShoe) to identify different functional postures and steps in people with stroke. The SmartShoe system consists of five force sensitive resistors built into a flexible insole and an accelerometer on the back of the shoe. Pressure and acceleration data are sent via Bluetooth to a smart phone. Methods Participants with stroke wore the SmartShoe while they performed activities of daily living (ADL) in sitting, standing and walking. Data from four participants were used to develop a multi-layer perceptron artificial neural network (ANN) to identify sitting, standing, and walking. A signal-processing algorithm used data from the pressure sensors to estimate number of steps taken while walking. The accuracy, precision and recall of the ANN for identifying the three functional postures were calculated using data from a different set of participants. Agreement between steps identified by SmartShoe and actual steps taken was analyzed using the Bland Altman method. Results The SmartShoe was able to accurately identify sitting, standing and walking. Accuracy, precision and recall were all greater than 95%. The mean difference between steps identified by SmartShoe and actual steps was less than 1 step. Discussion The SmartShoe was able to accurately identify different functional postures using a unique combination of pressure and acceleration data in people with stroke as they performed different ADLs. There was a strong level of agreement between actual steps taken and steps identified using the SmartShoe. Further study is needed to determine if the SmartShoe could be used to provide valid

  9. Correction of an active space telescope mirror using a deformable mirror in a woofer-tweeter configuration

    NASA Astrophysics Data System (ADS)

    Allen, Matthew R.; Kim, Jae Jun; Agrawal, Brij N.

    2016-04-01

    The Naval Postgraduate School's segmented mirror telescope (SMT) was developed using prototype silicon carbide active hybrid mirror technology to demonstrate lower cost and rapid manufacture of primary mirror segments for a space telescope. The developmental mirror segments used too few actuators limiting the ability to adequately correct the surface figure error. To address the unintended shortfall of the developmental mirrors, a deformable mirror is added to the SMT and control techniques are developed. The control techniques are similar to woofer-tweeter adaptive optics, where the SMT segment represents the woofer and the deformable mirror represents the tweeter. The optical design of an SMT woofer-tweeter system is presented, and the impacts of field angle magnification on the placement and size of the deformable mirror are analyzed. A space telescope woofer-tweeter wavefront control technique is proposed using a global influence matrix and closed-loop constrained minimization controller. The control technique simultaneously manipulates the woofer and tweeter mirrors. Simulation and experimental results demonstrate a significant improvement in wavefront error of the primary mirror and the control technique shows significant wavefront error improvement compared to sequentially controlling the woofer and tweeter mirrors.

  10. Influence of robotic shoal size, configuration, and activity on zebrafish behavior in a free-swimming environment.

    PubMed

    Butail, Sachit; Polverino, Giovanni; Phamduy, Paul; Del Sette, Fausto; Porfiri, Maurizio

    2014-12-15

    In animal studies, robots have been recently used as a valid tool for testing a wide spectrum of hypotheses. These robots often exploit visual or auditory cues to modulate animal behavior. The propensity of zebrafish, a model organism in biological studies, toward fish with similar color patterns and shape has been leveraged to design biologically inspired robots that successfully attract zebrafish in preference tests. With an aim of extending the application of such robots to field studies, here, we investigate the response of zebrafish to multiple robotic fish swimming at different speeds and in varying arrangements. A soft real-time multi-target tracking and control system remotely steers the robots in circular trajectories during the experimental trials. Our findings indicate a complex behavioral response of zebrafish to biologically inspired robots. More robots produce a significant change in salient measures of stress, with a fast robot swimming alone causing more freezing and erratic activity than two robots swimming slowly together. In addition, fish spend more time in the proximity of a robot when they swim far apart than when the robots swim close to each other. Increase in the number of robots also significantly alters the degree of alignment of fish motion with a robot. Results from this study are expected to advance our understanding of robot perception by live animals and aid in hypothesis-driven studies in unconstrained free-swimming environments. PMID:25239605

  11. Configuration of biological wastewater treatment line and influent composition as the main factors driving bacterial community structure of activated sludge.

    PubMed

    Jaranowska, Paulina; Cydzik-Kwiatkowska, Agnieszka; Zielińska, Magdalena

    2013-07-01

    The structure of microbial consortia in wastewater treatment facilities is a resultant of environmental conditions created by the operational parameters of the purification process. In the research, activated sludge from nine Polish wastewater treatment plants (WWTPs) was investigated at a molecular level to determine the impact of the complexity of biological treatment line and the influent composition on the species structure and the diversity of bacterial consortia. The community fingerprints and technological data were subjected to the canonical correspondence and correlation analyses. The number of separated biological processes realized in the treatment line and the presence of industrial wastewater in the influent were the key factors determining the species structure of total and ammonia-oxidizing bacteria in biomass. The N2O-reducers community composition depended significantly on the design of the facility; the highest species richness of denitrifiers was noted in the WWTPs with separated denitrification tanks. The contribution of industrial streams to the inflow affected the diversity of total and denitrifying bacterial consortia and diminished the diversity of ammonia oxidizers. The obtained data are valuable for engineers since they revealed the main factors, including the design of wastewater treatment plant, influencing the microbial groups critical for the stability of purification processes. PMID:23397107

  12. Electrolocation of objects in fluids by means of active sensor movements based on discrete EEVs.

    PubMed

    Wolf-Homeyer, Sabine; Engelmann, Jacob; Schneider, Axel

    2016-01-01

    Weakly electric fish use self-generated electric fields for communication and for active electrolocation. The sensor part of the biological system consists of a vast amount of electroreceptors which are distributed across the skin of the electric fish. Fish utilise changes of their position and body geometry to aid in the extraction of sensory information. Inspired by the biological model, this study looks for a fixed, minimal scanning strategy compiled of active receptor-system movements that allows unique identification of the positions of objects in the vicinity. The localisation method is based on the superposition of numerical extracted contour-rings of rotated and/or linearly shifted EEVs (Solberg et al 2008 Int. J. Rob. Res. 27 529-48), simulated by means of FEM. For the evaluation of a movement sequence, matrices of unique intersection points and respective contrast functions are introduced. The resultant optimal scanning strategy consists of a combination of a linear shift and a rotation of the original EEV. PMID:27530278

  13. Active site of mycobacterial dUTPase: Structural characteristics and a built-in sensor

    SciTech Connect

    Varga, Balazs; Barabas, Orsolya; Takacs, Eniko; Nagy, Nikolett; Nagy, Peter; Vertessy, Beata G.

    2008-08-15

    dUTPases are essential to eliminate dUTP for DNA integrity and provide dUMP for thymidylate biosynthesis. Mycobacterium tuberculosis apparently lacks any other thymidylate biosynthesis pathway, therefore dUTPase is a promising antituberculotic drug target. Crystal structure of the mycobacterial enzyme in complex with the isosteric substrate analog, {alpha},{beta}-imido-dUTP and Mg{sup 2+} at 1.5 A resolution was determined that visualizes the full-length C-terminus, previously not localized. Interactions of a conserved motif important in catalysis, the Mycobacterium-specific five-residue-loop insert and C-terminal tetrapeptide could now be described in detail. Stacking of C-terminal histidine upon the uracil moiety prompted replacement with tryptophan. The resulting sensitive fluorescent sensor enables fast screening for binding of potential inhibitors to the active site. K{sub d} for {alpha},{beta}-imido-dUTP binding to mycobacterial dUTPase is determined to be 10-fold less than for human dUTPase, which is to be considered in drug optimization. A robust continuous activity assay for kinetic screening is proposed.

  14. Atmospheric Chemistry Measurements in Schools and Outreach Activities with Low-cost Air Quality Sensors

    NASA Astrophysics Data System (ADS)

    Fleming, Z.; Monks, P. S.; McKenzie, K.

    2014-12-01

    The increasing range of low cost air quality sensors entering the market-place or being developed in-house in the last couple of years has led to many possibilities for using these instruments for public outreach activities or citizen science projects. A range of instruments sent out into local schools for the children to interpret and analyse the data and put the air quality in their area into context. A teaching package with tutorials has been developed to bring the data to life and link in with curriculum.The instruments have also been positioned around the city of Leicester in the UK to help understand the spatial variations in air quality and to assess the impact of retro-fitting buses on a busy bus route. The data is easily accessible online on a near real time basis and the various instruments can be compared with others around the country or the world from classrooms around the world.We will give an overview of the instrumentation with a comparison with commercial and cutting edge research instrumentation, the type of activities that were carried out and the public outreach forums where the data can be used.

  15. A simple strategy to monitor lipase activity using liquid crystal-based sensors.

    PubMed

    Hu, Qiong-Zheng; Jang, Chang-Hyun

    2012-09-15

    In this study, we developed a simple label-free technique for monitoring the enzymatic activity of lipase using liquid crystal (LC)-based sensors. The optical response of LCs changed from a bright to dark appearance when an aqueous solution of lipase was in contact with a nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), that was doped with glyceryl trioleate, which is a glyceride that can be enzymatically hydrolyzed by lipase. Since the oleic acid released from the enzymatic reaction could spontaneously form a self-assembled monolayer at the aqueous/LC interface due to its amphiphilic property, the orientation of the LCs transited from a planar to homeotropic state, which induced a change in the optical response of the LCs. We did not observe a bright-to-dark shift in the optical appearance of LCs when pure 5CB was immersed into the lipase solution. Moreover, we further confirmed the specificity of the enzymatic reaction by transferring an aqueous buffer solution not containing an analyte, or with bovine serum albumin (BSA) or trypsin onto the interface of aqueous solutions and the glyceryl trioleate-doped 5CB, which did not produce any distinctive contrast in the optical appearance. These results suggest the feasibility of measuring the enzymatic activity of lipase using the LC-based sensing technique. Furthermore, our strategy could also be used for the preparation of a self-assembled monolayer of carboxylates at the aqueous/LC interface. PMID:22967518

  16. Sequential formation of ion pairs during activation of a sodium channel voltage sensor

    PubMed Central

    DeCaen, Paul G.; Yarov-Yarovoy, Vladimir; Sharp, Elizabeth M.; Scheuer, Todd; Catterall, William A.

    2009-01-01

    Electrical signaling in biology depends upon a unique electromechanical transduction process mediated by the S4 segments of voltage-gated ion channels. These transmembrane segments are driven outward by the force of the electric field on positively charged amino acid residues termed “gating charges,” which are positioned at three-residue intervals in the S4 transmembrane segment, and this movement is coupled to opening of the pore. Here, we use the disulfide-locking method to demonstrate sequential ion pair formation between the fourth gating charge in the S4 segment (R4) and two acidic residues in the S2 segment during activation. R4 interacts first with E70 at the intracellular end of the S2 segment and then with D60 near the extracellular end. Analysis with the Rosetta Membrane method reveals the 3-D structures of the gating pore as these ion pairs are formed sequentially to catalyze the S4 transmembrane movement required for voltage-dependent activation. Our results directly demonstrate sequential ion pair formation that is an essential feature of the sliding helix model of voltage sensor function but is not compatible with the other widely discussed gating models. PMID:20007787

  17. Application of piezoelectric active-sensors for SHM of wind turbine blades

    SciTech Connect

    Park, Gyuhae; Taylor, Stuart G.; Farinholt, Kevin M; Farrar, Charles R

    2010-10-04

    The goal of this study is to characterize the dynamic response of a CX-100 wind blade and the design parameters of SHM techniques as they apply to wind turbine blades, and to investigate the performance of high-frequency active-sensing SHM techniques, including lamb wave and frequency response functions, as a way to monitor the health of a wind turbine blade. The results of the dynamic characterization will be used to validate a numerical model and understand the effect of structural damage on the performance of the blades. The focus of SHM study is to assess and compare the performance of each method in identifying incipient damage, with a special consideration given to field deployability. For experiments, a 9-m CX-100 blade was used. Overall, the methods yielded sufficient damage detection to warrant further investigation into field deployment. This paper also summarizes the SHM results of a full-scale fatigue test of 9-m CX-100 blade using piezoelectric active-sensors.

  18. Optimization of the configuration of a symmetric three-barrier resonant-tunneling structure as an active element of a quantum cascade detector

    SciTech Connect

    Tkach, N. V. Seti, Ju. A.

    2011-03-15

    On the basis of a model of rectangular potentials and different electron effective masses in wells and barriers of an open resonant-tunneling structure with identical outer barriers, a theory has been developed and the dynamic conductance caused by the interaction of the electromagnetic field with electrons passing through the structure has been calculated. Using the example of the three-barrier resonant-tunneling structure with In{sub 0.53}Ga{sub 0.47}As wells and In{sub 0.52}Al{sub 0.48}As barriers, it is shown that, independently of the geometrical sizes of potential wells and barriers, there exist three geometrical configurations (positions of the inner barrier with respect to outer ones) at which the nanosystem, as an active element, provides optimum operating conditions of the quantum cascade detector.

  19. Tracking human activity and well-being in natural environments using wearable sensors and experience sampling.

    PubMed

    Doherty, Sean T; Lemieux, Christopher J; Canally, Culum

    2014-04-01

    A growing range of studies have begun to document the health and well-being benefits associated with contact with nature. Most studies rely on generalized self-reports following engagement in the natural environment. The actual in-situ experience during contact with nature, and the environmental features and factors that evoke health benefits have remained relatively unexplored. Smartphones offer a new opportunity to monitor and interact with human subjects during everyday life using techniques such as Experience Sampling Methods (ESM) that involve repeated self-reports of experiences as they occur in-situ. Additionally, embedded sensors in smartphones such as Global Positioning Systems (GPS) and accelerometers can accurately trace human activities. This paper explores how these techniques can be combined to comprehensively explore the perceived health and well-being impacts of contact with nature. Custom software was developed to passively track GPS and accelerometer data, and actively prompt subjects to complete an ESM survey at regular intervals throughout their visit to a provincial park in Ontario, Canada. The ESM survey includes nine scale questions concerning moods and emotions, followed by a series of open-ended experiential questions that subjects provide recorded audio responses to. Pilot test results are used to illustrate the nature, quantity and quality of data obtained. Participant activities were clearly evident from GPS maps, including especially walking, cycling and sedate activities. From the ESM surveys, participants reported an average of 25 words per question, taking an average of 15 s to record them. Further qualitative analysis revealed that participants were willing to provide considerable insights into their experiences and perceived health impacts. The combination of passive and interactive techniques is sure to make larger studies of this type more affordable and less burdensome in the future, further enhancing the ability to understand

  20. An Intelligent Active Video Surveillance System Based on the Integration of Virtual Neural Sensors and BDI Agents

    NASA Astrophysics Data System (ADS)

    Gregorio, Massimo De

    In this paper we present an intelligent active video surveillance system currently adopted in two different application domains: railway tunnels and outdoor storage areas. The system takes advantages of the integration of Artificial Neural Networks (ANN) and symbolic Artificial Intelligence (AI). This hybrid system is formed by virtual neural sensors (implemented as WiSARD-like systems) and BDI agents. The coupling of virtual neural sensors with symbolic reasoning for interpreting their outputs, makes this approach both very light from a computational and hardware point of view, and rather robust in performances. The system works on different scenarios and in difficult light conditions.