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Sample records for bio-inspired speed detection

  1. Compressive Sensing Based Bio-Inspired Shape Feature Detection CMOS Imager

    NASA Technical Reports Server (NTRS)

    Duong, Tuan A. (Inventor)

    2015-01-01

    A CMOS imager integrated circuit using compressive sensing and bio-inspired detection is presented which integrates novel functions and algorithms within a novel hardware architecture enabling efficient on-chip implementation.

  2. Bio Inspired Swarm Algorithm for Tumor Detection in Digital Mammogram

    NASA Astrophysics Data System (ADS)

    Dheeba, J.; Selvi, Tamil

    Microcalcification clusters in mammograms is the significant early sign of breast cancer. Individual clusters are difficult to detect and hence an automatic computer aided mechanism will help the radiologist in detecting the microcalcification clusters in an easy and efficient way. This paper presents a new classification approach for detection of microcalcification in digital mammogram using particle swarm optimization algorithm (PSO) based clustering technique. Fuzzy C-means clustering technique, well defined for clustering data sets are used in combination with the PSO. We adopt the particle swarm optimization to search the cluster center in the arbitrary data set automatically. PSO can search the best solution from the probability option of the Social-only model and Cognition-only model. This method is quite simple and valid, and it can avoid the minimum local value. The proposed classification approach is applied to a database of 322 dense mammographic images, originating from the MIAS database. Results shows that the proposed PSO-FCM approach gives better detection performance compared to conventional approaches.

  3. Bio-inspired group modeling and analysis for intruder detection in mobile sensor/robotic networks.

    PubMed

    Fu, Bo; Xiao, Yang; Liang, Xiannuan; Philip Chen, C L

    2015-01-01

    Although previous bio-inspired models have concentrated on invertebrates (such as ants), mammals such as primates with higher cognitive function are valuable for modeling the increasingly complex problems in engineering. Understanding primates' social and communication systems, and applying what is learned from them to engineering domains is likely to inspire solutions to a number of problems. This paper presents a novel bio-inspired approach to determine group size by researching and simulating primate society. Group size does matter for both primate society and digital entities. It is difficult to determine how to group mobile sensors/robots that patrol in a large area when many factors are considered such as patrol efficiency, wireless interference, coverage, inter/intragroup communications, etc. This paper presents a simulation-based theoretical study on patrolling strategies for robot groups with the comparison of large and small groups through simulations and theoretical results. PMID:24846688

  4. A bio-inspired asynchronous skin system for crack detection applications

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    In many applications of structural health monitoring (SHM) it is imperative or advantageous to have large sensor arrays in order to properly sense the state of health of the structure. Typically these sensor networks are implemented by placing a large number of sensors over a structure and running individual cables from each sensor back to a central measurement station. Data is then collected from each sensor on the network at a constant sampling rate regardless of the current timescales at which events are acting on the structure. These conventional SHM sensor networks have a number of shortfalls. They tend to have a large number of cables that can represent a single point of failure for each sensor as well as add significant weight and installation costs. The constant sampling rate associated with each sensor very quickly leads to large amounts of data that must be analyzed, stored, and possibly transmitted to a remote user. This leads to increased demands on power consumption, bandwidth, and size. It also taxes our current techniques for managing large amounts of data. For the last decade the goal of the SHM community has been to endow structures with the functionality of a biological nervous system. Despite this goal the community has predominantly ignored the biological nervous system as inspiration for building structural nervous systems, choosing instead to focus on experimental mechanics and simulation techniques. In this work we explore the use of a novel, bio-inspired, SHM skin. This skin makes use of distributed computing and asynchronous communication techniques to alleviate the scale of the data management challenge as well as reduce power. The system also periodically sends a ‘heat beat’ signal to provide state-of-health updates. This conductive skin was implemented using conductive ink resistors as well as with graphene-oxide capacitors.

  5. Bio-inspired vision

    NASA Astrophysics Data System (ADS)

    Posch, C.

    2012-01-01

    Nature still outperforms the most powerful computers in routine functions involving perception, sensing and actuation like vision, audition, and motion control, and is, most strikingly, orders of magnitude more energy-efficient than its artificial competitors. The reasons for the superior performance of biological systems are subject to diverse investigations, but it is clear that the form of hardware and the style of computation in nervous systems are fundamentally different from what is used in artificial synchronous information processing systems. Very generally speaking, biological neural systems rely on a large number of relatively simple, slow and unreliable processing elements and obtain performance and robustness from a massively parallel principle of operation and a high level of redundancy where the failure of single elements usually does not induce any observable system performance degradation. In the late 1980`s, Carver Mead demonstrated that silicon VLSI technology can be employed in implementing ``neuromorphic'' circuits that mimic neural functions and fabricating building blocks that work like their biological role models. Neuromorphic systems, as the biological systems they model, are adaptive, fault-tolerant and scalable, and process information using energy-efficient, asynchronous, event-driven methods. In this paper, some basics of neuromorphic electronic engineering and its impact on recent developments in optical sensing and artificial vision are presented. It is demonstrated that bio-inspired vision systems have the potential to outperform conventional, frame-based vision acquisition and processing systems in many application fields and to establish new benchmarks in terms of redundancy suppression/data compression, dynamic range, temporal resolution and power efficiency to realize advanced functionality like 3D vision, object tracking, motor control, visual feedback loops, etc. in real-time. It is argued that future artificial vision systems

  6. Quality-of-service sensitivity to bio-inspired/evolutionary computational methods for intrusion detection in wireless ad hoc multimedia sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2012-06-01

    In the author's previous work, a cross-layer protocol approach to wireless sensor network (WSN) intrusion detection an identification is created with multiple bio-inspired/evolutionary computational methods applied to the functions of the protocol layers, a single method to each layer, to improve the intrusion-detection performance of the protocol over that of one method applied to only a single layer's functions. The WSN cross-layer protocol design embeds GAs, anti-phase synchronization, ACO, and a trust model based on quantized data reputation at the physical, MAC, network, and application layer, respectively. The construct neglects to assess the net effect of the combined bioinspired methods on the quality-of-service (QoS) performance for "normal" data streams, that is, streams without intrusions. Analytic expressions of throughput, delay, and jitter, coupled with simulation results for WSNs free of intrusion attacks, are the basis for sensitivity analyses of QoS metrics for normal traffic to the bio-inspired methods.

  7. Bio-Inspired Antifouling Strategies

    NASA Astrophysics Data System (ADS)

    Kirschner, Chelsea M.; Brennan, Anthony B.

    2012-08-01

    Biofouling is a complex, dynamic problem that globally impacts both the economy and environment. Interdisciplinary research in marine biology, polymer science, and engineering has led to the implementation of bio-inspired strategies for the development of the next generation of antifouling marine coatings. Natural fouling defense mechanisms have been mimicked through chemical, physical, and/or stimuli-responsive strategies. This review outlines the detrimental effects associated with biofouling, describes the theoretical basis for antifouling coating design, and highlights prominent advances in bio-inspired antifouling technologies.

  8. Bio-inspired approach for intelligent unattended ground sensors

    NASA Astrophysics Data System (ADS)

    Hueber, Nicolas; Raymond, Pierre; Hennequin, Christophe; Pichler, Alexander; Perrot, Maxime; Voisin, Philippe; Moeglin, Jean-Pierre

    2015-05-01

    Improving the surveillance capacity over wide zones requires a set of smart battery-powered Unattended Ground Sensors capable of issuing an alarm to a decision-making center. Only high-level information has to be sent when a relevant suspicious situation occurs. In this paper we propose an innovative bio-inspired approach that mimics the human bi-modal vision mechanism and the parallel processing ability of the human brain. The designed prototype exploits two levels of analysis: a low-level panoramic motion analysis, the peripheral vision, and a high-level event-focused analysis, the foveal vision. By tracking moving objects and fusing multiple criteria (size, speed, trajectory, etc.), the peripheral vision module acts as a fast relevant event detector. The foveal vision module focuses on the detected events to extract more detailed features (texture, color, shape, etc.) in order to improve the recognition efficiency. The implemented recognition core is able to acquire human knowledge and to classify in real-time a huge amount of heterogeneous data thanks to its natively parallel hardware structure. This UGS prototype validates our system approach under laboratory tests. The peripheral analysis module demonstrates a low false alarm rate whereas the foveal vision correctly focuses on the detected events. A parallel FPGA implementation of the recognition core succeeds in fulfilling the embedded application requirements. These results are paving the way of future reconfigurable virtual field agents. By locally processing the data and sending only high-level information, their energy requirements and electromagnetic signature are optimized. Moreover, the embedded Artificial Intelligence core enables these bio-inspired systems to recognize and learn new significant events. By duplicating human expertise in potentially hazardous places, our miniature visual event detector will allow early warning and contribute to better human decision making.

  9. Switchable bio-inspired adhesives

    NASA Astrophysics Data System (ADS)

    Kroner, Elmar

    2015-03-01

    Geckos have astonishing climbing abilities. They can adhere to almost any surface and can run on walls and even stick to ceilings. The extraordinary adhesion performance is caused by a combination of a complex surface pattern on their toes and the biomechanics of its movement. These biological dry adhesives have been intensely investigated during recent years because of the unique combination of adhesive properties. They provide high adhesion, allow for easy detachment, can be removed residue-free, and have self-cleaning properties. Many aspects have been successfully mimicked, leading to artificial, bio-inspired, patterned dry adhesives, and were addressed and in some aspects they even outperform the adhesion capabilities of geckos. However, designing artificial patterned adhesion systems with switchable adhesion remains a big challenge; the gecko's adhesion system is based on a complex hierarchical surface structure and on advanced biomechanics, which are both difficult to mimic. In this paper, two approaches are presented to achieve switchable adhesion. The first approach is based on a patterned polydimethylsiloxane (PDMS) polymer, where adhesion can be switched on and off by applying a low and a high compressive preload. The switch in adhesion is caused by a reversible mechanical instability of the adhesive silicone structures. The second approach is based on a composite material consisting of a Nickel- Titanium (NiTi) shape memory alloy and a patterned adhesive PDMS layer. The NiTi alloy is trained to change its surface topography as a function of temperature, which results in a change of the contact area and of alignment of the adhesive pattern towards a substrate, leading to switchable adhesion. These examples show that the unique properties of bio-inspired adhesives can be greatly improved by new concepts such as mechanical instability or by the use of active materials which react to external stimuli.

  10. Autonomous UAV persistent surveillance using bio-inspired strategies

    NASA Astrophysics Data System (ADS)

    Burman, Jerry; Hespanha, Joao; Madhow, Upamanyu; Isaacs, Jason; Venkateswaran, Sriram; Pham, Tien

    2012-06-01

    A team consisting of Teledyne Scientific Company, the University of California at Santa Barbara, the Army Research Laboratory, the Engineer Research and Development Center, and IBM UK is developing technologies in support of automated data exfiltration from heterogeneous battlefield sensor networks to enhance situational awareness for dismounts and command echelons. Unmanned aerial vehicles (UAV) provide an effective means to autonomously collect data from a sparse network of unattended ground sensors (UGSs) that cannot communicate with each other. UAVs are used to reduce the system reaction time by generating autonomous collection routes that are data-driven. Bioinspired techniques for autonomous search provide a novel strategy to detect, capture and fuse data from heterogeneous sensor networks. The bio-inspired algorithm is based on chemotaxis or the motion of bacteria seeking nutrients in their environment. Field tests of a bio-inspired system that routed UAVs were conducted in June 2011 at Camp Roberts, CA. The field test results showed that such a system can autonomously detect and locate the source of terrestrial events with very high accuracy and visually verify the event. In June 2011, field tests of the system were completed and include the use of multiple autonomously controlled UAVs, detection and disambiguation of multiple acoustic events occurring in short time frames, optimal sensor placement based on local phenomenology and the use of the International Technology Alliance (ITA) Sensor Network Fabric. The system demonstrated TRL 6 performance in the field at Camp Roberts.

  11. Heterogeneous sensor networks: a bio-inspired overlay architecture

    NASA Astrophysics Data System (ADS)

    Burman, Jerry; Hespanha, Joao; Madhow, Upamanyu; Klein, Daniel; Isaacs, Jason; Venkateswaran, Sriram; Pham, Tien

    2010-04-01

    Teledyne Scientific Company, the University of California at Santa Barbara (UCSB) and the Army Research Lab are developing technologies for automated data exfiltration from heterogeneous sensor networks through the Institute for Collaborative Biotechnologies (ICB). Unmanned air vehicles (UAV) provide an effective means to autonomously collect data from unattended ground sensors (UGSs) that cannot communicate with each other. UAVs are used to reduce the system reaction time by generating autonomous data-driven collection routes. Bio-inspired techniques for search provide a novel strategy to detect, capture and fuse data across heterogeneous sensors. A fast and accurate method has been developed for routing UAVs and localizing an event by fusing data from a sparse number of UGSs; it leverages a bio-inspired technique based on chemotaxis or the motion of bacteria seeking nutrients in their environment. The system was implemented and successfully tested using a high level simulation environment using a flight simulator to emulate a UAV. A field test was also conducted in November 2009 at Camp Roberts, CA using a UAV provided by AeroMech Engineering. The field test results showed that the system can detect and locate the source of an acoustic event with an accuracy of about 3 meters average circular error.

  12. Bio-inspired flapping UAV design: a university perspective

    NASA Astrophysics Data System (ADS)

    Han, Jae-Hung; Lee, Jun-Seong; Kim, Dae-Kwan

    2009-03-01

    Bio-inspired design to make artificial flappers fly does not just imitate biological systems as closely as possible, but also transferring the flappers' own functionalities to engineering solutions. This paper summarizes some key technical issues and the states-of-art of bio-inspired design of flapping UAVs with an introduction to authors' recent research results in this field.

  13. Bio-inspired synthesis of metal nanomaterials and applications.

    PubMed

    Huang, Jiale; Lin, Liqin; Sun, Daohua; Chen, Huimei; Yang, Dapeng; Li, Qingbiao

    2015-10-01

    This critical review focuses on recent advances in the bio-inspired synthesis of metal nanomaterials (MNMs) using microorganisms, viruses, plants, proteins and DNA molecules as well as their applications in various fields. Prospects in the design of bio-inspired MNMs for novel applications are also discussed. PMID:26083903

  14. Bio-inspired networks for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Han, Bing; Huang, Yuanlin; Li, Ruopeng; Peng, Qiang; Luo, Junyi; Pei, Ke; Herczynski, Andrzej; Kempa, Krzysztof; Ren, Zhifeng; Gao, Jinwei

    2014-11-01

    Modern optoelectronics needs development of new materials characterized not only by high optical transparency and electrical conductivity, but also by mechanical strength, and flexibility. Recent advances employ grids of metallic micro- and nanowires, but the overall performance of the resulting material composites remains unsatisfactory. In this work, we propose a new strategy: application of natural scaffoldings perfected by evolution. In this context, we study two bio-inspired networks for two specific optoelectronic applications. The first network, intended for solar cells, light sources and similar devices, has a quasi-fractal structure and is derived directly from a chemically extracted leaf venation system. The second network is intended for touch screens and flexible displays, and is obtained by metalizing a spider’s silk web. We demonstrate that each of these networks attain an exceptional optoelectonic and mechanical performance for its intended purpose, providing a promising direction in the development of more efficient optoelectronic devices.

  15. Tough, bio-inspired hybrid materials

    SciTech Connect

    Munch, Etienne; Launey, Maximimilan E.; Alsem, Daan H.; Saiz, Eduardo; Tomsia, Antoni P.; Ritchie, Robert O.

    2008-10-06

    The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs extremely difficult to replicate synthetically. Here we emulate Nature's toughening mechanisms through the combination of two ordinary compounds, aluminum oxide and polymethylmethacrylate, into ice-templated structures whose toughness can be over 300 times (in energy terms) that of their constituents. The final product is a bulk hybrid ceramic material whose high yield strength and fracture toughness ({approx}200 MPa and {approx}30 MPa{radical}m) provide specific properties comparable to aluminum alloys. These model materials can be used to identify the key microstructural features that should guide the synthesis of bio-inspired ceramic-based composites with unique strength and toughness.

  16. Aurelia aurita bio-inspired tilt sensor

    NASA Astrophysics Data System (ADS)

    Smith, Colin; Villanueva, Alex; Priya, Shashank

    2012-10-01

    The quickly expanding field of mobile robots, unmanned underwater vehicles, and micro-air vehicles urgently needs a cheap and effective means for measuring vehicle inclination. Commonly, tilt or inclination has been mathematically derived from accelerometers; however, there is inherent error in any indirect measurement. This paper reports a bio-inspired tilt sensor that mimics the natural balance organ of jellyfish, called the ‘statocyst’. Biological statocysts from the species Aurelia aurita were characterized by scanning electron microscopy to investigate the morphology and size of the natural sensor. An artificial tilt sensor was then developed by using printed electronics that incorporates a novel voltage divider concept in conjunction with small surface mount devices. This sensor was found to have minimum sensitivity of 4.21° with a standard deviation of 1.77°. These results open the possibility of developing elegant tilt sensor architecture for both air and water based platforms.

  17. Bio-inspired odor-based navigation

    NASA Astrophysics Data System (ADS)

    Porter, Maynard J., III; Vasquez, Juan R.

    2006-05-01

    The ability of many insects, especially moths, to locate either food or a member of the opposite sex is an amazing achievement. There are numerous scenarios where having this ability embedded into ground-based or aerial vehicles would be invaluable. This paper presents results from a 3-D computer simulation of an Unmanned Aerial Vehicle (UAV) autonomously tracking a chemical plume to its source. The simulation study includes a simulated dynamic chemical plume, 6-degree of freedom, nonlinear aircraft model, and a bio-inspired navigation algorithm. The emphasis of this paper is the development and analysis of the navigation algorithm. The foundation of this algorithm is a fuzzy controller designed to categorize where in the plume the aircraft is located: coming into the plume, in the plume, exiting the plume, or out of the plume.

  18. Bio-Inspired Self-Cleaning Surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Kesong; Jiang, Lei

    2012-08-01

    Self-cleaning surfaces have drawn a lot of interest for both fundamental research and practical applications. This review focuses on the recent progress in mechanism, preparation, and application of self-cleaning surfaces. To date, self-cleaning has been demonstrated by the following four conceptual approaches: (a) TiO2-based superhydrophilic self-cleaning, (b) lotus effect self-cleaning (superhydrophobicity with a small sliding angle), (c) gecko setae-inspired self-cleaning, and (d) underwater organisms-inspired antifouling self-cleaning. Although a number of self-cleaning products have been commercialized, the remaining challenges and future outlook of self-cleaning surfaces are also briefly addressed. Through evolution, nature, which has long been a source of inspiration for scientists and engineers, has arrived at what is optimal. We hope this review will stimulate interdisciplinary collaboration among material science, chemistry, biology, physics, nanoscience, engineering, etc., which is essential for the rational design and reproducible construction of bio-inspired multifunctional self-cleaning surfaces in practical applications.

  19. Bio-inspired Fillers for Mechanical Enhancement

    NASA Astrophysics Data System (ADS)

    Korley, Lashanda

    2012-02-01

    An examination of natural materials has offered a new perspective on the development of multi-functional materials with enhanced mechanical properties. One important lesson from nature is the utilization of composite structures to impart improved mechanical behavior and enhanced functionality using nanofillers. A relatively unexplored expansion of this bio-inspired, nanoscale filler approach to high performance materials is the incorporation of responsive, multi-functional reinforcing elements in polymeric composites with the goal of combining superior mechanical behavior that can be tuned with additional functionality, such as sensing and bioactivity. One approach is the use of self-assembling small molecules that form uniform, one-dimensional nanostructures as an emerging class of filler components. Another pathway toward mechanical enhancement is the incorporation of stimuli-responsive and high-modulus electrospun nanofibers. We have probed the utilization of high-aspect ratio, self-assembled small molecules and responsive electrospun nanofibers as all-organic nanofillers to achieve significant modulus changes within elastomeric matrices. The influence of matrix-filler interactions and the role of hierarchical organization in these nature-inspired composites will be discussed. Potential applications in barrier technology and drug delivery have also been explored.

  20. Bio-Inspired Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Warncke, Kurt

    2009-11-01

    The areas of solar-powered catalysts for energy rich fuels formation and bio-inspired molecular assemblies for integrating photon-to-fuels pathways have been identified by the Office of Basic Energy Sciences of the U. S. Department of Energy as challenges for the next generation of sustainable, high-efficiency solar energy conversion systems [1]. The light-harvesting, energy-transducing and carbon compound-synthesizing (carbon dioxide-fixing) reactions that are encompassed by natural photosynthesis offer molecular paradigms for efficient free energy capture and storage. We seek to emulate these features in cell-free, protein-based systems. Our goal is to transform the robust (alpha,beta)8-barrel fold of an enzyme that naturally catalyzes radical reactions into a catalytic module for the reduction of carbon dioxide to formate, by using the cobalt-containing cobalamins and other organocobalt centers. The activation of the catalytic center will be driven by photo-reduction, by using soluble and attached organic or semiconductor architectures. Progress on the biochemical, chemical, physical, and molecular biological (including rational design of high binding affinity and reactivity towards carbon dioxide) approaches to the development of the photocatalytic system will be presented.[4pt] [1] Lewis, N.; Crabtree, G. In: Basic Research Needs for Solar Energy Utilization, Basic Energy Sciences Workshop on Solar Energy Utilization, Energy, U.S. Department of Energy, Office of Science: 2005.

  1. Catalytic applications of bio-inspired nanomaterials

    NASA Astrophysics Data System (ADS)

    Pacardo, Dennis Kien Balaong

    The biomimetic synthesis of Pd nanoparticles was presented using the Pd4 peptide, TSNAVHPTLRHL, isolated from combinatorial phage display library. Using this approach, nearly monodisperse and spherical Pd nanoparticles were generated with an average diameter of 1.9 +/- 0.4 nm. The peptide-based nanocatalyst were employed in the Stille coupling reaction under energy-efficient and environmentally friendly reaction conditions of aqueous solvent, room temperature and very low catalyst loading. To this end, the Pd nanocatalyst generated high turnover frequency (TOF) value and quantitative yields using ≥ 0.005 mol% Pd as well as catalytic activities with different aryl halides containing electron-withdrawing and electron-donating groups. The Pd4-capped Pd nanoparticles followed the atom-leaching mechanism and were found to be selective with respect to substrate identity. On the other hand, the naturally-occurring R5 peptide (SSKKSGSYSGSKGSKRRIL) was employed in the synthesis of biotemplated Pd nanomaterials which showed morphological changes as a function of Pd:peptide ratio. TOF analysis for hydrogenation of olefinic alcohols showed similar catalytic activity regardless of nanomorphology. Determination of catalytic properties of these bio-inspired nanomaterials are important as they serve as model system for alternative green catalyst with applications in industrially important transformations.

  2. Investigating the relationship between planform and performance in bio-inspired aquatic propulsion

    NASA Astrophysics Data System (ADS)

    Badaoui, Oliver J.; Quinn, Daniel B.; Dewey, Peter A.; Smits, Alexander J.

    2013-11-01

    Experiments are conducted to investigate the effects of caudal fin planform shape on the hydrodynamic performance of bio-inspired aquatic propulsors. To isolate the effect of planform shape the surface area of the fins is held constant while the planform shape is systematically varied to incorporate bio-inspired designs that are consistent with those observed in nature. The self-propelled swimming speed and power consumption of heaving flexible panels of varying planform are measured in a stationary water tank. Particle image velocimetry is also employed to better understand the connection between the wake structures produced by the oscillating fins and their performance characteristics. Results are compared and analyzed in an effort to identify specific shape features that lead to a performance benefit or detriment. Supported by the Office of Naval Research under Program Director Dr. Bob Brizzolara, MURI grant number N00014-08-1-0642.

  3. Bio-Inspired Engineering of Exploration Systems

    NASA Technical Reports Server (NTRS)

    Thakoor, Sanita

    2003-01-01

    level of exploration mode (say, a large conventional lander/rover) in the vicinity. A widespread and affordable exploration of new/hazardous sites at lower cost and risk would thus become possible by utilizing a faster aerial flyer to cover long ranges and deploying a variety of function- specific, smaller biomorphic explorers for distributed sensing and local sample acquisition. Several conceptual biomorphic missions for planetary and terrestrial exploration applications have been illustrated in "Surface-Launched Explorers for Reconnaissance/ Scouting" (NPO-20871), NASA Tech Briefs, Vol. 26, No. 4 (April, 2002), page 69 and "Bio-Inspired Engineering of Exploration Systems," Journal of Space Mission Architecture, Issue 2, Fall 2000, pages 49-79.

  4. A Bio-Inspired AER Temporal Tri-Color Differentiator Pixel Array.

    PubMed

    Farian, Łukasz; Leñero-Bardallo, Juan Antonio; Häfliger, Philipp

    2015-10-01

    This article investigates the potential of a bio-inspired vision sensor with pixels that detect transients between three primary colors. The in-pixel color processing is inspired by the retinal color opponency that are found in mammalian retinas. Color transitions in a pixel are represented by voltage spikes, which are akin to a neuron's action potential. These spikes are conveyed off-chip by the Address Event Representation (AER) protocol. To achieve sensitivity to three different color spectra within the visual spectrum, each pixel has three stacked photodiodes at different depths in the silicon substrate. The sensor has been fabricated in the standard TSMC 90 nm CMOS technology. A post-processing method to decode events into color transitions has been proposed and implemented as a custom interface to display real-time color changes in the visual scene. Experimental results are provided. Color transitions can be detected at high speed (up to 2.7 kHz). The sensor has a dynamic range of 58 dB and a power consumption of 22.5 mW. This type of sensor can be of use in industrial, robotics, automotive and other applications where essential information is contained in transient emissions shifts within the visual spectrum. PMID:26540694

  5. Bio-inspired color sketch for eco-friendly printing

    NASA Astrophysics Data System (ADS)

    Safonov, Ilia V.; Tolstaya, Ekaterina V.; Rychagov, Michael N.; Lee, Hokeun; Kim, Sang Ho; Choi, Donchul

    2012-01-01

    Saving of toner/ink consumption is an important task in modern printing devices. It has a positive ecological and social impact. We propose technique for converting print-job pictures to a recognizable and pleasant color sketches. Drawing a "pencil sketch" from a photo relates to a special area in image processing and computer graphics - non-photorealistic rendering. We describe a new approach for automatic sketch generation which allows to create well-recognizable sketches and to preserve partly colors of the initial picture. Our sketches contain significantly less color dots then initial images and this helps to save toner/ink. Our bio-inspired approach is based on sophisticated edge detection technique for a mask creation and multiplication of source image with increased contrast by this mask. To construct the mask we use DoG edge detection, which is a result of blending of initial image with its blurred copy through the alpha-channel, which is created from Saliency Map according to Pre-attentive Human Vision model. Measurement of percentage of saved toner and user study proves effectiveness of proposed technique for toner saving in eco-friendly printing mode.

  6. Bio-inspired aquatic robotics by untethered piezohydroelastic actuation.

    PubMed

    Cen, L; Erturk, A

    2013-03-01

    This paper investigates fish-like aquatic robotics using flexible bimorphs made of macro-fiber composite (MFC) piezoelectric laminates for carangiform locomotion. In addition to noiseless and efficient actuation over a range of frequencies, geometric scalability, and simple design, bimorph propulsors made of MFCs offer a balance between the actuation force and velocity response for performance enhancement in bio-inspired swimming. The experimental component of the presented work focuses on the characterization of an elastically constrained MFC bimorph propulsor for thrust generation in quiescent water as well as the development of a robotic fish prototype combining a microcontroller and a printed-circuit-board amplifier to generate high actuation voltage for untethered locomotion. From the theoretical standpoint, a distributed-parameter electroelastic model including the hydrodynamic effects and actuator dynamics is coupled with the elongated-body theory for predicting the mean thrust in quiescent water. In-air and underwater experiments are performed to verify the incorporation of hydrodynamic effects in the linear actuation regime. For electroelastically nonlinear actuation levels, experimentally obtained underwater vibration response is coupled with the elongated-body theory to predict the thrust output. The measured mean thrust levels in quiescent water (on the order of ∼10 mN) compare favorably with thrust levels of biological fish. An untethered robotic fish prototype that employs a single bimorph fin (caudal fin) for straight swimming and turning motions is developed and tested in free locomotion. A swimming speed of 0.3 body-length/second (7.5 cm s⁻¹ swimming speed for 24.3 cm body length) is achieved at 5 Hz for a non-optimized main body-propulsor bimorph combination under a moderate actuation voltage level. PMID:23348365

  7. Bio-inspired supramolecular self-assembly towards soft nanomaterials

    PubMed Central

    LIN, Yiyang; MAO, Chuanbin

    2011-01-01

    Supramolecular self-assembly has proven to be a reliable approach towards versatile nanomaterials based on multiple weak intermolecular forces. In this review, the development of bio-inspired supramolecular self-assembly into soft materials and their applications are summarized. Molecular systems used in bio-inspired “bottom-up self-assembly” involve small organic molecules, peptides or proteins, nucleic acids, and viruses. Self-assembled soft nanomaterials have been exploited in various applications such as inorganic nanomaterial synthesis, drug or gene delivery, tissue engineering, and so on. PMID:21980594

  8. Optic flow estimation on trajectories generated by bio-inspired closed-loop flight.

    PubMed

    Shoemaker, Patrick A; Hyslop, Andrew M; Humbert, J Sean

    2011-05-01

    We generated panoramic imagery by simulating a fly-like robot carrying an imaging sensor, moving in free flight through a virtual arena bounded by walls, and containing obstructions. Flight was conducted under closed-loop control by a bio-inspired algorithm for visual guidance with feedback signals corresponding to the true optic flow that would be induced on an imager (computed by known kinematics and position of the robot relative to the environment). The robot had dynamics representative of a housefly-sized organism, although simplified to two-degree-of-freedom flight to generate uniaxial (azimuthal) optic flow on the retina in the plane of travel. Surfaces in the environment contained images of natural and man-made scenes that were captured by the moving sensor. Two bio-inspired motion detection algorithms and two computational optic flow estimation algorithms were applied to sequences of image data, and their performance as optic flow estimators was evaluated by estimating the mutual information between outputs and true optic flow in an equatorial section of the visual field. Mutual information for individual estimators at particular locations within the visual field was surprisingly low (less than 1 bit in all cases) and considerably poorer for the bio-inspired algorithms that the man-made computational algorithms. However, mutual information between weighted sums of these signals and comparable sums of the true optic flow showed significant increases for the bio-inspired algorithms, whereas such improvement did not occur for the computational algorithms. Such summation is representative of the spatial integration performed by wide-field motion-sensitive neurons in the third optic ganglia of flies. PMID:21626306

  9. Principle of bio-inspired insect wing rotational hinge design

    NASA Astrophysics Data System (ADS)

    Fei, Fan

    A principle for designing and fabricating bio-inspired miniature artificial insect flapping wing using flexure rotational hinge design is presented. A systematic approach of selecting rotational hinge stiffness value is proposed. Based on the understanding of flapping wing aerodynamics, a dynamic simulation is constructed using the established quasi-steady model and the wing design. Simulations were performed to gain insight on how different parameters affect the wing rotational response. Based on system resonance a model to predict the optimal rotational hinge stiffness based on given wing parameter and flapping wing kinematic is proposed. By varying different wing parameters, the proposed method is shown to be applicable to a wide range of wing designs with different sizes and shapes. With the selected hinge stiffness value, aspects of the rotational joint design is discussed and an integrated wing-hinge structure design using laminated carbon fiber and polymer film is presented. Manufacturing process of such composite structure is developed to achieve high accuracy and repeatability. The yielded hinge stiffness is verified by measurements. To validate the proposed model, flapping wing experiments were conducted. A flapping actuation set up is built using DC motor and a controller is implemented on a microcontroller to track desired wing stroke kinematic. Wing stroke and rotation kinematic were extracted using a high speed camera and the lift generation is evaluated. A total of 49 flapping experiments were presented, experimental data shows good correlation with the model's prediction. With the wing rotational hinge stiffness designed so that the rotational resonant frequency is twice as the stroke frequency, the resulting wing rotation generates near optimal lift. With further simulation, the proposed model shows low sensitivity to wing parameter variation. As a result, giving a design parameter of a flapping wing robot platform, the proposed principle can

  10. Bio-inspired Hierarchical Nanowebs for Green Catalysis.

    PubMed

    Lee, Kyoung G; Lee, Subeom; Chang, Sung-Jin; Choi, Bong Gill; Seo, Jeongeun; Sangalang, Arvin; Kim, Do Hyun; Park, Tae Jung; Lee, Moon-Keun; Lee, Seok Jae; Lee, Haiwon

    2015-09-01

    Bio-inspired 3D hierarchical nanowebs are fabricated using silicon micropillars, carbon nanotubes (CNT), and manganese oxide. The Si pillars act as artificial branches for growing CNTs and the secondary metal coating strengthens the structures. The simple but effective structure provides both chemical and mechanical stability to be used as a green catalyst for recycling waste polymers into raw materials. PMID:26060049

  11. Energy evaluation of a bio-inspired gait modulation method for quadrupedal locomotion.

    PubMed

    Fukuoka, Yasuhiro; Fukino, Kota; Habu, Yasushi; Mori, Yoshikazu

    2015-08-01

    We have proposed a bio-inspired gait modulation method, by means of which a simulated quadruped model can successfully perform smooth, autonomous gait transitions from a walk to a trot to a gallop, as observed in animals. The model is equipped with a rhythm generator called a central pattern generator (CPG) for each leg. The lateral neighbouring CPGs are mutually and inhibitorily coupled, and the CPG network is hardwired to produce a trot. Adding only the simple feedback of body tilt to each CPG, which was based on input from the postural reflex, led to the emergence of un-programmed walking and galloping at low and high speeds, respectively. Although this autonomous gait transition was a consequence of postural adaptation, it coincidentally also resulted in the minimization of energy consumption, as observed in real animals. In simulations at a variety of constant speeds the energy cost was lower for walking at low speeds and for galloping at high speeds than it was for trotting. Moreover, each gait transition occurred at the optimal speed, such that the model minimised its energy consumption. Thus, gait transitions in simulations that included the bio-inspired gait modulation method were similar to those observed in animals, even from the perspective of energy consumption. This method should therefore be a preferred choice for motion generation and control in biomimetic quadrupedal locomotion. PMID:26241690

  12. Bio-inspired design of dental multilayers: experiments and model.

    PubMed

    Niu, Xinrui; Rahbar, Nima; Farias, Stephen; Soboyejo, Wole

    2009-12-01

    This paper combines experiments, simulations and analytical modeling that are inspired by the stress reductions associated with the functionally graded structures of the dentin-enamel-junctions (DEJs) in natural teeth. Unlike conventional crown structures in which ceramic crowns are bonded to the bottom layer with an adhesive layer, real teeth do not have a distinct "adhesive layer" between the enamel and the dentin layers. Instead, there is a graded transition from enamel to dentin within a approximately 10 to 100 microm thick regime that is called the Dentin Enamel Junction (DEJ). In this paper, a micro-scale, bio-inspired functionally graded structure is used to bond the top ceramic layer (zirconia) to a dentin-like ceramic-filled polymer substrate. The bio-inspired functionally graded material (FGM) is shown to exhibit higher critical loads over a wide range of loading rates. The measured critical loads are predicted using a rate dependent slow crack growth (RDEASCG) model. The implications of the results are then discussed for the design of bio-inspired dental multilayers. PMID:19716103

  13. Vibration isolation by exploring bio-inspired structural nonlinearity.

    PubMed

    Wu, Zhijing; Jing, Xingjian; Bian, Jing; Li, Fengming; Allen, Robert

    2015-10-01

    Inspired by the limb structures of animals/insects in motion vibration control, a bio-inspired limb-like structure (LLS) is systematically studied for understanding and exploring its advantageous nonlinear function in passive vibration isolation. The bio-inspired system consists of asymmetric articulations (of different rod lengths) with inside vertical and horizontal springs (as animal muscle) of different linear stiffness. Mathematical modeling and analysis of the proposed LLS reveal that, (a) the system has very beneficial nonlinear stiffness which can provide flexible quasi-zero, zero and/or negative stiffness, and these nonlinear stiffness properties are adjustable or designable with structure parameters; (b) the asymmetric rod-length ratio and spring-stiffness ratio present very beneficial factors for tuning system equivalent stiffness; (c) the system loading capacity is also adjustable with the structure parameters which presents another flexible benefit in application. Experiments and comparisons with existing quasi-zero-stiffness isolators validate the advantageous features above, and some discussions are also given about how to select structural parameters for practical applications. The results would provide an innovative bio-inspired solution to passive vibration control in various engineering practice. PMID:26448392

  14. Bio-inspired UAV routing, source localization, and acoustic signature classification for persistent surveillance

    NASA Astrophysics Data System (ADS)

    Burman, Jerry; Hespanha, Joao; Madhow, Upamanyu; Pham, Tien

    2011-06-01

    A team consisting of Teledyne Scientific Company, the University of California at Santa Barbara and the Army Research Laboratory* is developing technologies in support of automated data exfiltration from heterogeneous battlefield sensor networks to enhance situational awareness for dismounts and command echelons. Unmanned aerial vehicles (UAV) provide an effective means to autonomously collect data from a sparse network of unattended ground sensors (UGSs) that cannot communicate with each other. UAVs are used to reduce the system reaction time by generating autonomous collection routes that are data-driven. Bio-inspired techniques for search provide a novel strategy to detect, capture and fuse data. A fast and accurate method has been developed to localize an event by fusing data from a sparse number of UGSs. This technique uses a bio-inspired algorithm based on chemotaxis or the motion of bacteria seeking nutrients in their environment. A unique acoustic event classification algorithm was also developed based on using swarm optimization. Additional studies addressed the problem of routing multiple UAVs, optimally placing sensors in the field and locating the source of gunfire at helicopters. A field test was conducted in November of 2009 at Camp Roberts, CA. The field test results showed that a system controlled by bio-inspired software algorithms can autonomously detect and locate the source of an acoustic event with very high accuracy and visually verify the event. In nine independent test runs of a UAV, the system autonomously located the position of an explosion nine times with an average accuracy of 3 meters. The time required to perform source localization using the UAV was on the order of a few minutes based on UAV flight times. In June 2011, additional field tests of the system will be performed and will include multiple acoustic events, optimal sensor placement based on acoustic phenomenology and the use of the International Technology Alliance (ITA

  15. Analytical development of a binuclear oxo-manganese complex bio-inspired on oxidase enzyme for doping control analysis of acetazolamide.

    PubMed

    Machini, Wesley B S; Teixeira, Marcos F S

    2016-05-15

    A bio-inspired electrochemical sensor using a binuclear oxo-manganese complex was evaluated and applied in the detection of a substance associated with doping in sports: acetazolamide (ACTZ). Investigation was made of the influence of different experimental variables on the electrocatalytic oxidation of ACTZ by the bio-inspired sensor, such as pH and interfering species. The bio-inspired sensor showed the best response in the range from 5.00×10(-9) to 7.00×10(-8) mol L(-1) ACTZ, with a linear range from 5.00×10(-9) to 2.50×10(-8) mol L(-1) and a detection limit of 4.76×10(-9) mol L(-1). The sensor exhibited characteristics similar to the Michaelis-Menten model of an enzymatic electrode, due to the use of a multinucleated complex of manganese with μ-oxo units, which was able to mimic the properties of enzymes with manganese as a cofactor in their composition, such as Mn-containing oxidase. The determination of ACTZ with the bio-inspired sensor was evaluated using three different synthetic biological fluids (plasma, saliva, and urine), demonstrating its viability for use with real samples. The analysis of ACTZ in real urine samples using the bio-inspired sensor, simulating the method adopted by the World Anti-Doping Agency, which revealed viable, suggesting a new and promising platform to be used in these analysis. PMID:26745790

  16. Bio-Inspired Micromechanical Directional Acoustic Sensor

    NASA Astrophysics Data System (ADS)

    Swan, William; Alves, Fabio; Karunasiri, Gamani

    Conventional directional sound sensors employ an array of spatially separated microphones and the direction is determined using arrival times and amplitudes. In nature, insects such as the Ormia ochracea fly can determine the direction of sound using a hearing organ much smaller than the wavelength of sound it detects. The fly's eardrums are mechanically coupled, only separated by about 1 mm, and have remarkable directional sensitivity. A micromechanical sensor based on the fly's hearing system was designed and fabricated on a silicon on insulator (SOI) substrate using MEMS technology. The sensor consists of two 1 mm2 wings connected using a bridge and to the substrate using two torsional legs. The dimensions of the sensor and material stiffness determine the frequency response of the sensor. The vibration of the wings in response to incident sound at the bending resonance was measured using a laser vibrometer and found to be about 1 μm/Pa. The electronic response of the sensor to sound was measured using integrated comb finger capacitors and found to be about 25 V/Pa. The fabricated sensors showed good directional sensitivity. In this talk, the design, fabrication and characteristics of the directional sound sensor will be described. Supported by ONR and TDSI.

  17. Complex biological and bio-inspired systems

    SciTech Connect

    Ecke, Robert E

    2009-01-01

    The understanding and characterization ofthe fundamental processes of the function of biological systems underpins many of the important challenges facing American society, from the pathology of infectious disease and the efficacy ofvaccines, to the development of materials that mimic biological functionality and deliver exceptional and novel structural and dynamic properties. These problems are fundamentally complex, involving many interacting components and poorly understood bio-chemical kinetics. We use the basic science of statistical physics, kinetic theory, cellular bio-chemistry, soft-matter physics, and information science to develop cell level models and explore the use ofbiomimetic materials. This project seeks to determine how cell level processes, such as response to mechanical stresses, chemical constituents and related gradients, and other cell signaling mechanisms, integrate and combine to create a functioning organism. The research focuses on the basic physical processes that take place at different levels ofthe biological organism: the basic role of molecular and chemical interactions are investigated, the dynamics of the DNA-molecule and its phylogenetic role are examined and the regulatory networks of complex biochemical processes are modeled. These efforts may lead to early warning algorithms ofpathogen outbreaks, new bio-sensors to detect hazards from pathomic viruses to chemical contaminants. Other potential applications include the development of efficient bio-fuel alternative-energy processes and the exploration ofnovel materials for energy usages. Finally, we use the notion of 'coarse-graining,' which is a method for averaging over less important degrees of freedom to develop computational models to predict cell function and systems-level response to disease, chemical stress, or biological pathomic agents. This project supports Energy Security, Threat Reduction, and the missions of the DOE Office of Science through its efforts to accurately

  18. Bio-inspired method and system for actionable intelligence

    NASA Astrophysics Data System (ADS)

    Khosla, Deepak; Chelian, Suhas E.

    2009-05-01

    This paper describes a bio-inspired VISion based actionable INTelligence system (VISINT) that provides automated capabilities to (1) understand objects, patterns, events and behaviors in vision data; (2) translate this understanding into timely recognition of novel and anomalous entities; and (3) discover underlying hierarchies and relationships between disparate labels entered by multiple users to provide a consistent data representation. VISINT is both a system and a novel collection of novel bio-inspired algorithms/modules. These modules can be used independently for various aspects of the actionable intelligence problem or sequenced together for an end-to-end actionable intelligence system. The algorithms can be useful in many other applications such as scene understanding, behavioral analysis, automatic surveillance systems, etc. The bio-inspired algorithms are a novel combination of hierarchical spatial and temporal networks based on the Adaptive Resonance Theory (ART). The novel aspects of this work are that it is an end-to-end system for actionable intelligence that combines existing and novel implementations of various modules in innovative ways to develop a system concept for actionable intelligence. Although there are other algorithms/implementations of several of the modules in VISINT, they suffer from various limitations and often system integration is not considered. The overall VISINT system can be viewed an incremental learning system where no offline training is required and data from multiple sources and times can be seamlessly integrated. The user is in the loop, but due to the semi-supervised nature of the underlying algorithms, only significant variations of entities, not all false alarms, are shown to the user. It does not forget the past even with new learning. While VISINT is designed as a vision-based system, it could also work with other kinds of sensor data that can recognize and locate individual objects in the scene. Beyond that stage

  19. Wetting-controlled strategies: from theories to bio-inspiration.

    PubMed

    Song, Cheng; Zheng, Yongmei

    2014-08-01

    Creatures have evolved the unique wetting-controlled strategies on their surfaces to collect water for the sake of survival, such as Beetle back, spider silk and plant leaf as well, which inspires us to open the area of novel researches. In this feature article, we review the theoretical basis of wetting-controlling regarding of wettability and highlight the biological wetting-controlled strategies in water transport, and water collection, and also introduce some bio-inspired materials with water collection properties. It is significant to design the novel materials that would be used in the fields of responsive, smart catalysis, filtration and sensing besides water collection. PMID:24290249

  20. Bio-inspired solid phase extraction sorbent material for cocaine: a cross reactivity study.

    PubMed

    Montesano, Camilla; Sergi, Manuel; Perez, German; Curini, Roberta; Compagnone, Dario; Mascini, Marcello

    2014-12-01

    The binding specificity of a bio-inspired hexapeptide (QHWWDW) versus cocaine and four other drugs such as 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), phencyclidine and morphine was computationally studied and then experimentally confirmed in solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC/MS) detection. In simulation, the hexapeptide-drug complexes were docked with different scoring functions and considering pH chemical environment. In experimental, the cross reactivity of the selected hexapeptide was tested as SPE sorbent versus cocaine and other four drugs using buffer solutions at pH 4 and 7. Significant differences in specific retention were found between cocaine (97% of recovery) and both morphine (45% of recovery) and phencyclidine (60% of recovery), but less for ecstasies (average recovery 69%). In agreement with docking simulation, the hexapeptide showed the highest recovery with best specificity versus cocaine at pH 7 with an experimentally binding constant of 2.9 × 10(6)M(-1). The bio-inspired sorbent material analytical performances were compared with a commercial reversed phase cartridge confirming the hexapeptide specificity to cocaine and validating simulated data. PMID:25159425

  1. Cytocompatibility of bio-inspired silicon carbide ceramics.

    PubMed

    López-Alvarez, M; de Carlos, A; González, P; Serra, J; León, B

    2010-10-01

    Due to its good mechanical and biochemical properties and, also, because of its unique interconnected porosity, bio-inspired silicon carbide (bioSiC) can be considered as a promising material for biomedical applications, including controlled drug delivery devices and tissue engineering scaffolds. This innovative material is produced by molten-Si infiltration of carbon templates, obtained by controlled pyrolysis of vegetable precursors. The final SiC ceramic presents a porous-interconnected microstructure that mimics the natural hierarchical structure of bone tissue and allows the internal growth of tissue, as well as favors angiogenesis. In the present work, the in vitro cytocompatibility of the bio-inspired SiC ceramics obtained, in this case, from the tree sapelli (Entandrophragma cylindricum) was evaluated. The attachment, spreading, cytoskeleton organization, proliferation, and mineralization of the preosteoblastic cell line MC3T3-E1 were analyzed for up to 28 days of incubation by scanning electron microscopy, interferometric profilometry, confocal laser scanning microscopy, MTT assay, as well as red alizarin staining and quantification. Cells seeded onto these ceramics were able to attach, spread, and proliferate properly with the maintenance of the typical preosteoblastic morphology throughout the time of culture. A certain level of mineralization on the surface of the sapelli-based SiC ceramics is observed. These results demonstrated the cytocompatibility of this porous and hierarchical material. PMID:20737554

  2. Bio-inspired strategies for anti-icing.

    PubMed

    Lv, Jianyong; Song, Yanlin; Jiang, Lei; Wang, Jianjun

    2014-04-22

    Undesired ice accumulation leads to severe economic issues and, in some cases, loss of lives. Although research on anti-icing has been carried out for decades, environmentally harmless, economical, and efficient strategies for anti-icing remain to be developed. Recent researches have provided new insights into the icing phenomenon and shed light on some promising bio-inspired anti-icing strategies. The present review critically categorizes and discusses recent developments. Effectively trapping air in surface textures of superhydrophobic surfaces weakens the interaction of the surfaces with liquid water, which enables timely removal of impacting and condensed water droplets before freezing occurs. When ice already forms, ice adhesion can be significantly reduced if liquid is trapped in surface textures as a lubricating layer. As such, ice could be shed off by an action of wind or its gravity. In addition, bio-inspired anti-icing strategies via trapping or introducing other media, such as phase change materials and antifreeze proteins, are discussed. PMID:24592934

  3. Bio-Inspired Cyber Security for Smart Grid Deployments

    SciTech Connect

    McKinnon, Archibald D.; Thompson, Seth R.; Doroshchuk, Ruslan A.; Fink, Glenn A.; Fulp, Errin W.

    2013-05-01

    mart grid technologies are transforming the electric power grid into a grid with bi-directional flows of both power and information. Operating millions of new smart meters and smart appliances will significantly impact electric distribution systems resulting in greater efficiency. However, the scale of the grid and the new types of information transmitted will potentially introduce several security risks that cannot be addressed by traditional, centralized security techniques. We propose a new bio-inspired cyber security approach. Social insects, such as ants and bees, have developed complex-adaptive systems that emerge from the collective application of simple, light-weight behaviors. The Digital Ants framework is a bio-inspired framework that uses mobile light-weight agents. Sensors within the framework use digital pheromones to communicate with each other and to alert each other of possible cyber security issues. All communication and coordination is both localized and decentralized thereby allowing the framework to scale across the large numbers of devices that will exist in the smart grid. Furthermore, the sensors are light-weight and therefore suitable for implementation on devices with limited computational resources. This paper will provide a brief overview of the Digital Ants framework and then present results from test bed-based demonstrations that show that Digital Ants can identify a cyber attack scenario against smart meter deployments.

  4. Effects of flexibility on bio-inspired aquatic propulsion

    NASA Astrophysics Data System (ADS)

    Dewey, Peter; Boschitsch, Birgitt; Smits, Alexander

    2012-11-01

    We present the results of an experimental investigation aimed at understanding the role that flexibility plays in bio-inspired aquatic propulsion. A rectangular pitching panel apparatus, where both the flexibility and aspect ratio can be systematically varied, is utilized as a simplified model for bio-inspired propulsion in water at a Reynolds number of 7200. It is found that, when optimized, flexibility can double the thrust produced and propulsive efficiency achieved in comparison to a rigid panel. There is a notable thrust enhancement when the flexible panels are operating near resonance; however, it is found that resonance is not the primary mechanism governing efficient propulsion. Peaks in propulsive efficiency are found below, at, and above the resonant frequency depending on the flexibility of the panel. Finally, a scaling law is derived that is shown to collapse the thrust production, power consumption, and propulsive efficiency data across all panels examined. The authors would like to acknowledge the generous support from the Office of Naval Research under Program Director Dr. Bob Brizzolara, MURI grant number N00014-08-1-0642.

  5. Bio-inspired antireflective hetero-nanojunctions with enhanced photoactivity

    NASA Astrophysics Data System (ADS)

    Qi, Dianpeng; Zheng, Liyan; Cao, Xuebo; Jiang, Yueyue; Xu, Hongbo; Zhang, Yanyan; Yang, Bingjie; Sun, Yinghui; Hng, Huey Hoon; Lu, Nan; Chi, Lifeng; Chen, Xiaodong

    2013-11-01

    A bio-inspired antireflective hetero-nanojunction structure has been fabricated by the hydrothermal growth of ZnO nanorods on silicon micro-pyramids. It has been shown that this structure suppresses light reflection more effectively resulting in a high photocurrent response and good charge separation simultaneously. The strategy provides a means to enhance solar energy conversion.A bio-inspired antireflective hetero-nanojunction structure has been fabricated by the hydrothermal growth of ZnO nanorods on silicon micro-pyramids. It has been shown that this structure suppresses light reflection more effectively resulting in a high photocurrent response and good charge separation simultaneously. The strategy provides a means to enhance solar energy conversion. Electronic supplementary information (ESI) available: HRTEM image and XRD pattern of a ZnO nanorod; schematic representation of the photoanode behavior, as well as the concentration change of rhodamine 6G through the photodegradation process over many repeats. See DOI: 10.1039/c3nr04011a

  6. Introducing Students to Bio-Inspiration and Biomimetic Design: A Workshop Experience

    ERIC Educational Resources Information Center

    Santulli, Carlo; Langella, Carla

    2011-01-01

    In recent years, bio-inspired approach to design has gained considerable interest between designers, engineers and end-users. However, there are difficulties in introducing bio-inspiration concepts in the university curriculum in that they involve multi-disciplinary work, which can only possibly be successfully delivered by a team with integrated…

  7. Wireless synapses in bio-inspired neural networks

    NASA Astrophysics Data System (ADS)

    Jannson, Tomasz; Forrester, Thomas; Degrood, Kevin

    2009-05-01

    Wireless (virtual) synapses represent a novel approach to bio-inspired neural networks that follow the infrastructure of the biological brain, except that biological (physical) synapses are replaced by virtual ones based on cellular telephony modeling. Such synapses are of two types: intracluster synapses are based on IR wireless ones, while intercluster synapses are based on RF wireless ones. Such synapses have three unique features, atypical of conventional artificial ones: very high parallelism (close to that of the human brain), very high reconfigurability (easy to kill and to create), and very high plasticity (easy to modify or upgrade). In this paper we analyze the general concept of wireless synapses with special emphasis on RF wireless synapses. Also, biological mammalian (vertebrate) neural models are discussed for comparison, and a novel neural lensing effect is discussed in detail.

  8. Bio-inspired polarized skylight navigation: a review

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Wan, Yongqin; Li, Lijing

    2015-12-01

    The idea of using skylight polarization in navigation is learned from animals such as desert ants and honeybees. Various research groups have been working on the development of novel navigation systems inspired by polarized skylight. The research of background in polarized skylight navigation is introduced, and basic principle of the insects navigation is expatiated. Then, the research progress status at home and abroad in skylight polarization pattern, three bio-inspired polarized skylight navigation sensors and polarized skylight navigation are reviewed. Finally, the research focuses in the field of polarized skylight navigation are analyzed. At the same time, the trend of development and prospect in the future are predicted. It is believed that the review is helpful to people understand polarized skylight navigation and polarized skylight navigation sensors.

  9. Bio-inspired artificial iriodphores based on capillary origami

    NASA Astrophysics Data System (ADS)

    Manakasettharn, Supone; Taylor, J. Ashley; Krupenkin, Tom

    2011-03-01

    Many marine organisms have evolved complex optical mechanisms of dynamic skin color control that allow them to drastically change their visual appearance. In particular, cephalopods have developed especially effective dynamic color control mechanism based on the mechanical actuation of the micro-scale optical structures, which produce either variable degrees of area coverage by a given color (chromatophores) or variations in spatial orientation of the reflective and diffractive surfaces (iridophores). In this work we describe bio-inspired artificial iridophores based on electrowetting-controlled capillary origami. We describe the developed microfabrication approach, characterize mechanical and optical properties of the obtained microstructures and discuss their electrowetting-based actuation. The obtained experimental results are in good agreement with a simple theoretical model based on electrocapillarity and elasticity theory. The results of the work can enable a broad range of novel optical devices.

  10. Flow over bio-inspired 3D herringbone wall riblets

    NASA Astrophysics Data System (ADS)

    Chen, Huawei; Rao, Fugang; Shang, Xiaopeng; Zhang, Deyuan; Hagiwara, Ichiro

    2014-03-01

    Under the inspiration of small riblets of shark skin, the microgroove drag reduction riblets whose direction set along fluid flow have been widely investigated. Herringbone-type riblets of bird flight feather are seldom exploited although bird also has excellent flight performance. Inspired from the flight feather, novel bio-inspired plane-3D (p-3D) and spatial-3D (s-3D) herringbone wall riblets are proposed. Through experiment measurement of drag reduction in water tunnel, maximum drag reduction of p-3D and s-3D herringbone riblets was about 17 and 20 %, higher than traditional microgroove riblets. Moreover, significant change of drag reduction was also found by change of the angle between herringbone riblets. In particular, maximum drag reduction occurred as angle between herringbone riblets was about 60° close to real flight feather, which indicates that microstructure of bird flight feather has great impact on flight performance.

  11. Development of a bio-inspired transformable robotic fin.

    PubMed

    Yang, Yikun; Xia, Yu; Qin, Fenghua; Xu, Min; Li, Weihua; Zhang, Shiwu

    2016-01-01

    Fish swim by oscillating their pectoral fins forwards and backwards in a cyclic motion such that their geometric parameters and aspect ratios change according to how fast or slow a fish wants to swim; these complex motions result in a complicated hydrodynamic response. This paper focuses on the dynamic change in the shape of a fin to improve the underwater propulsion of bio-inspired mechanism. To do this, a novel transformable robotic fin has been developed to investigate how this change in shape affects the hydrodynamic forces acting on the fin. This robotic fin has a multi-link frame and a flexible surface skin where changes in shape are activated by a purpose designed multi-link mechanism driven by a transformation motor. A drag platform has been designed to study the performance of this variable robotic fin. Numerous experiments were carried out to determine how various controlling modes affect the thrust capability of this fin. The kinematic parameters associated with this robotic fin include the oscillating frequency and amplitude, and the drag velocity. The fin has four modes to control the cyclic motion; these were also investigated in combination with the variable kinematic parameters. The results will help us understand the locomotion performance of this transformable robotic fin. Note that different controlling modes influence the propulsive performance of this robotic fin, which means its propulsive performance can be optimized in a changing environment by adapting its shape. This study facilitates the development of bio-inspired unmanned underwater vehicles with a very high swimming performance. PMID:27580003

  12. An Approach of Bio-inspired Hybrid Model for Financial Markets

    NASA Astrophysics Data System (ADS)

    Simić, Dragan; Gajić, Vladeta; Simić, Svetlana

    Biological systems are inspiration for the design of optimisation and classification models. Applying various forms of bio-inspired algorithms may be a very high-complex system. Modelling of financial markets is challenging for several reasons, because many plausible factors impact on it. An automated trading on financial market is not a new phenomenon. The model of bio-inspired hybrid adaptive trading system based on technical indicators usage by grammatical evolution and moving window is presented in this paper. The proposed system is just one of possible bio-inspired system which can be used in financial forecast, corporate failure prediction or bond rating company.

  13. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    SciTech Connect

    Cha, Jennifer N.; Wang, Joseph

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  14. Optical properties of bio-inspired peptide nanotubes

    NASA Astrophysics Data System (ADS)

    Handelman, Amir; Apter, Boris; Rosenman, Gil

    2016-04-01

    Supramolecular self-assembled bio-inspired peptide nanostructures are favorable to be implemented in diverse nanophotonics applications due to their superior physical properties such as wideband optical transparency, high second-order nonlinear response, waveguiding properties and more. Here, we focus on the optical properties found in di-phenylalanine peptide nano-architectures, with special emphasize on their linear and nonlinear optical waveguiding effects. Using both simulation and experiments, we show their ability to passively guide light at both fundamental and second-harmonic frequencies. In addition, we show that at elevated temperatures, 140-180°C, these native supramolecular structures undergo irreversible thermally induced transformation via re-assembling into completely new thermodynamically stable phase having nanofiber morphology similar to those of amyloid fibrils. In this new phase, the peptide nanofibers lose their second-order nonlinear response, while exhibit profound modification of optoelectronic properties followed by the appearance of visible (blue and green) photoluminescence (PL). Our study propose a new generation of multifunctional optical waveguides with variety of characteristics, which self-assembled into 1D-elongated nanostructures and could be used as building blocks of many integrated photonic devices.

  15. Miniaturized unified imaging system using bio-inspired fluidic lens

    NASA Astrophysics Data System (ADS)

    Tsai, Frank S.; Cho, Sung Hwan; Qiao, Wen; Kim, Nam-Hyong; Lo, Yu-Hwa

    2008-08-01

    Miniaturized imaging systems have become ubiquitous as they are found in an ever-increasing number of devices, such as cellular phones, personal digital assistants, and web cameras. Until now, the design and fabrication methodology of such systems have not been significantly different from conventional cameras. The only established method to achieve focusing is by varying the lens distance. On the other hand, the variable-shape crystalline lens found in animal eyes offers inspiration for a more natural way of achieving an optical system with high functionality. Learning from the working concepts of the optics in the animal kingdom, we developed bio-inspired fluidic lenses for a miniature universal imager with auto-focusing, macro, and super-macro capabilities. Because of the enormous dynamic range of fluidic lenses, the miniature camera can even function as a microscope. To compensate for the image quality difference between the central vision and peripheral vision and the shape difference between a solid-state image sensor and a curved retina, we adopted a hybrid design consisting of fluidic lenses for tunability and fixed lenses for aberration and color dispersion correction. A design of the world's smallest surgical camera with 3X optical zoom capabilities is also demonstrated using the approach of hybrid lenses.

  16. Bio-inspired Fabrication of Complex Hierarchical Structure in Silicon.

    PubMed

    Gao, Yang; Peng, Zhengchun; Shi, Tielin; Tan, Xianhua; Zhang, Deqin; Huang, Qiang; Zou, Chuanping; Liao, Guanglan

    2015-08-01

    In this paper, we developed a top-down method to fabricate complex three dimensional silicon structure, which was inspired by the hierarchical micro/nanostructure of the Morpho butterfly scales. The fabrication procedure includes photolithography, metal masking, and both dry and wet etching techniques. First, microscale photoresist grating pattern was formed on the silicon (111) wafer. Trenches with controllable rippled structures on the sidewalls were etched by inductively coupled plasma reactive ion etching Bosch process. Then, Cr film was angled deposited on the bottom of the ripples by electron beam evaporation, followed by anisotropic wet etching of the silicon. The simple fabrication method results in large scale hierarchical structure on a silicon wafer. The fabricated Si structure has multiple layers with uniform thickness of hundreds nanometers. We conducted both light reflection and heat transfer experiments on this structure. They exhibited excellent antireflection performance for polarized ultraviolet, visible and near infrared wavelengths. And the heat flux of the structure was significantly enhanced. As such, we believe that these bio-inspired hierarchical silicon structure will have promising applications in photovoltaics, sensor technology and photonic crystal devices. PMID:26369172

  17. Biomimetic and bio-inspired uses of mollusc shells.

    PubMed

    Morris, J P; Wang, Y; Backeljau, T; Chapelle, G

    2016-06-01

    Climate change and ocean acidification are likely to have a profound effect on marine molluscs, which are of great ecological and economic importance. One process particularly sensitive to climate change is the formation of biominerals in mollusc shells. Fundamental research is broadening our understanding of the biomineralization process, as well as providing more informed predictions on the effects of climate change on marine molluscs. Such studies are important in their own right, but their value also extends to applied sciences. Biominerals, organic/inorganic hybrid materials with many remarkable physical and chemical properties, have been studied for decades, and the possibilities for future improved use of such materials for society are widely recognised. This article highlights the potential use of our understanding of the shell biomineralization process in novel bio-inspired and biomimetic applications. It also highlights the potential for the valorisation of shells produced as a by-product of the aquaculture industry. Studying shells and the formation of biominerals will inspire novel functional hybrid materials. It may also provide sustainable, ecologically- and economically-viable solutions to some of the problems created by current human resource exploitation. PMID:27083864

  18. A bio-inspired memory model for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Zhu, Yong

    2009-04-01

    Long-term structural health monitoring (SHM) systems need intelligent management of the monitoring data. By analogy with the way the human brain processes memories, we present a bio-inspired memory model (BIMM) that does not require prior knowledge of the structure parameters. The model contains three time-domain areas: a sensory memory area, a short-term memory area and a long-term memory area. First, the initial parameters of the structural state are specified to establish safety criteria. Then the large amount of monitoring data that falls within the safety limits is filtered while the data outside the safety limits are captured instantly in the sensory memory area. Second, disturbance signals are distinguished from danger signals in the short-term memory area. Finally, the stable data of the structural balance state are preserved in the long-term memory area. A strategy for priority scheduling via fuzzy c-means for the proposed model is then introduced. An experiment on bridge tower deformation demonstrates that the proposed model can be applied for real-time acquisition, limited-space storage and intelligent mining of the monitoring data in a long-term SHM system.

  19. Electrowetting-controlled bio-inspired artificial iridophores

    NASA Astrophysics Data System (ADS)

    Manakasettharn, Supone; Taylor, J. Ashley; Krupenkin, Tom

    2011-10-01

    Many marine organisms have evolved complex optical mechanisms of dynamic skin color control that allow them to drastically change their visual appearance. In particular, cephalopods have developed especially effective dynamic color control mechanism based on the mechanical actuation of the micro-scale optical structures, which produce either variable degrees of area coverage by a given color (chromatophores) or variations in spatial orientation of the reflective and diffractive surfaces (iridophores). In this work we describe the design, fabrication and characterization of electrowetting-controlled bio-inspired artificial iridophores. The developed iridophores geometrically resemble microflowers with flexible reflective petals. The microflowers are fabricated on a silicon substrate using surface micromachining techniques. After fabrication a small droplet of conductive liquid is deposited at the center of each microflower. This causes the flower petals to partially wrap around the droplet forming a structure similar to capillary origami. The dynamic control over the degree of wrapping is achieved by applying a voltage differential between the conductive core of the petals and the droplet. The applied voltage causes dynamic contact angle change between the droplet and each of the petals due to the electrowetting effect. We have characterized mechanical and optical properties of the microstructures and discuss their electrowetting-based actuation. These experimental results are in good agreement with a 3D theoretical model based on electrocapillarity and elasticity theory. This work forms the basis for a broad range of novel optical devices.

  20. Bio-Inspired Stretchable Absolute Pressure Sensor Network

    PubMed Central

    Guo, Yue; Li, Yu-Hung; Guo, Zhiqiang; Kim, Kyunglok; Chang, Fu-Kuo; Wang, Shan X.

    2016-01-01

    A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4’’ wafer, has 77 nodes and can be mounted on various curved surfaces to cover an area up to 0.64 m × 0.64 m, which is 100 times larger than its original size. Due to Micro Electro-Mechanical system (MEMS) surface micromachining technology, ultrathin sensing nodes can be realized with thicknesses of less than 100 µm. Additionally, good linearity and high sensitivity (~14 mV/V/bar) have been achieved. Since the MEMS sensor process has also been well integrated with a flexible polymer substrate process, the entire sensor network can be fabricated in a time-efficient and cost-effective manner. Moreover, an accurate pressure contour can be obtained from the sensor network. Therefore, this absolute pressure sensor network holds significant promise for smart vehicle applications, especially for unmanned aerial vehicles. PMID:26729134

  1. Optimized bio-inspired stiffening design for an engine nacelle.

    PubMed

    Lazo, Neil; Vodenitcharova, Tania; Hoffman, Mark

    2015-12-01

    Structural efficiency is a common engineering goal in which an ideal solution provides a structure with optimized performance at minimized weight, with consideration of material mechanical properties, structural geometry, and manufacturability. This study aims to address this goal in developing high performance lightweight, stiff mechanical components by creating an optimized design from a biologically-inspired template. The approach is implemented on the optimization of rib stiffeners along an aircraft engine nacelle. The helical and angled arrangements of cellulose fibres in plants were chosen as the bio-inspired template. Optimization of total displacement and weight was carried out using a genetic algorithm (GA) coupled with finite element analysis. Iterations showed a gradual convergence in normalized fitness. Displacement was given higher emphasis in optimization, thus the GA optimization tended towards individual designs with weights near the mass constraint. Dominant features of the resulting designs were helical ribs with rectangular cross-sections having large height-to-width ratio. Displacement reduction was at 73% as compared to an unreinforced nacelle, and is attributed to the geometric features and layout of the stiffeners, while mass is maintained within the constraint. PMID:26531222

  2. A Bio-Inspired Herbal Tea Flavour Assessment Technique

    PubMed Central

    Zakaria, Nur Zawatil Isqi; Masnan, Maz Jamilah; Zakaria, Ammar; Shakaff, Ali Yeon Md

    2014-01-01

    Herbal-based products are becoming a widespread production trend among manufacturers for the domestic and international markets. As the production increases to meet the market demand, it is very crucial for the manufacturer to ensure that their products have met specific criteria and fulfil the intended quality determined by the quality controller. One famous herbal-based product is herbal tea. This paper investigates bio-inspired flavour assessments in a data fusion framework involving an e-nose and e-tongue. The objectives are to attain good classification of different types and brands of herbal tea, classification of different flavour masking effects and finally classification of different concentrations of herbal tea. Two data fusion levels were employed in this research, low level data fusion and intermediate level data fusion. Four classification approaches; LDA, SVM, KNN and PNN were examined in search of the best classifier to achieve the research objectives. In order to evaluate the classifiers' performance, an error estimator based on k-fold cross validation and leave-one-out were applied. Classification based on GC-MS TIC data was also included as a comparison to the classification performance using fusion approaches. Generally, KNN outperformed the other classification techniques for the three flavour assessments in the low level data fusion and intermediate level data fusion. However, the classification results based on GC-MS TIC data are varied. PMID:25010697

  3. A bio-inspired herbal tea flavour assessment technique.

    PubMed

    Zakaria, Nur Zawatil Isqi; Masnan, Maz Jamilah; Zakaria, Ammar; Shakaff, Ali Yeon Md

    2014-01-01

    Herbal-based products are becoming a widespread production trend among manufacturers for the domestic and international markets. As the production increases to meet the market demand, it is very crucial for the manufacturer to ensure that their products have met specific criteria and fulfil the intended quality determined by the quality controller. One famous herbal-based product is herbal tea. This paper investigates bio-inspired flavour assessments in a data fusion framework involving an e-nose and e-tongue. The objectives are to attain good classification of different types and brands of herbal tea, classification of different flavour masking effects and finally classification of different concentrations of herbal tea. Two data fusion levels were employed in this research, low level data fusion and intermediate level data fusion. Four classification approaches; LDA, SVM, KNN and PNN were examined in search of the best classifier to achieve the research objectives. In order to evaluate the classifiers' performance, an error estimator based on k-fold cross validation and leave-one-out were applied. Classification based on GC-MS TIC data was also included as a comparison to the classification performance using fusion approaches. Generally, KNN outperformed the other classification techniques for the three flavour assessments in the low level data fusion and intermediate level data fusion. However, the classification results based on GC-MS TIC data are varied. PMID:25010697

  4. Bio-Inspired Stretchable Absolute Pressure Sensor Network.

    PubMed

    Guo, Yue; Li, Yu-Hung; Guo, Zhiqiang; Kim, Kyunglok; Chang, Fu-Kuo; Wang, Shan X

    2016-01-01

    A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4'' wafer, has 77 nodes and can be mounted on various curved surfaces to cover an area up to 0.64 m × 0.64 m, which is 100 times larger than its original size. Due to Micro Electro-Mechanical system (MEMS) surface micromachining technology, ultrathin sensing nodes can be realized with thicknesses of less than 100 µm. Additionally, good linearity and high sensitivity (~14 mV/V/bar) have been achieved. Since the MEMS sensor process has also been well integrated with a flexible polymer substrate process, the entire sensor network can be fabricated in a time-efficient and cost-effective manner. Moreover, an accurate pressure contour can be obtained from the sensor network. Therefore, this absolute pressure sensor network holds significant promise for smart vehicle applications, especially for unmanned aerial vehicles. PMID:26729134

  5. Copper removal using bio-inspired polydopamine coated natural zeolites.

    PubMed

    Yu, Yang; Shapter, Joseph G; Popelka-Filcoff, Rachel; Bennett, John W; Ellis, Amanda V

    2014-05-30

    Herein, for the first time, natural clinoptilolite-rich zeolite powders modified with a bio-inspired adhesive, polydopamine (PDA), have been systematically studied as an adsorbent for copper cations (Cu(II)) from aqueous solution. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) revealed successful grafting of PDA onto the zeolite surface. The effects of pH (2-5.5), PDA treatment time (3-24h), contact time (0 to 24h) and initial Cu(II) ion concentrations (1 to 500mgdm(-3)) on the adsorption of Cu(II) ions were studied using atomic absorption spectroscopy (AAS) and neutron activation analysis (NAA). The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. The maximum adsorption capacities of Cu(II) were shown to be 14.93mgg(-1) for pristine natural zeolite and 28.58mgg(-1) for PDA treated zeolite powders. This impressive 91.4% increase in Cu(II) ion adsorption capacity is attributed to the chelating ability of the PDA on the zeolite surface. Furthermore studies of recyclability using NAA showed that over 50% of the adsorbed copper could be removed in mild concentrations (0.01M or 0.1M) of either acid or base. PMID:24731937

  6. A bio-inspired test system for bionic above-knee prosthetic knees

    NASA Astrophysics Data System (ADS)

    Wang, Dai-Hua; Xu, Lei; Fu, Qiang; Yuan, Gang

    2013-04-01

    Recently, prosthetic knees in the developing stage are usually tested by installing them on amputees' stumps directly or on above-knee prostheses (AKPs) test platforms. Although amputees can fully provide the actual motion state of the thigh, immature prosthetic knees may hurt amputees. For AKPs test platforms, it just can partly simulate the actual motion state of the thigh with limitation of the motion curve of the thigh, the merits or demerits of newly developed bionic above-knee prosthetic knees cannot be accessed thoroughly. Aiming at the defects of two testing methods, this paper presents a bio-inspired AKPs test system for bionic above-knee prosthetic knees. The proposed bio-inspired AKPs test system is composed of a AKPs test platform, a control system, and a bio-inspired system. The AKPs test platform generates the motion of the thigh simulation mechanism (TSM) via two screw pairs with servo motors. The bio-inspired system includes the tester and the bio-inspired sensor wore by the tester. The control system, which is inspired by the bio-inspired system, generates the control command signal to move the TSM of the AKPs test platform. The bio-inspired AKPs test system is developed and experimentally tested with a commercially available prosthetic knee. The research results show that the bio-inspired AKPs test system can not only ensure the safety of the testers, but also track all kinds of the actual motion state of the thigh of the testers in real time.

  7. A new bio-inspired decision chain for UAV sense-and-avoid applications

    NASA Astrophysics Data System (ADS)

    Fallavollita, P.; Cimini, F.; Balsi, M.; Esposito, S.; Jankowski, S.

    This work, after a preliminary feasibility study using a Matlab environment simulation, defines the design and the real hardware testing of a new bio-inspired decision chain for UAV sense-and-avoid applications. Relying on a single and cheap visible camera sensor, computer vision, bio-inspired and automatic decision algorithms have been adopted and implemented on a specific ARM embedded platform through C++/OpenCV coding. A first data set processing, really captured on flight, has been presented.

  8. Three-Dimensional-Printing of Bio-Inspired Composites.

    PubMed

    Xiang Gu, Grace; Su, Isabelle; Sharma, Shruti; Voros, Jamie L; Qin, Zhao; Buehler, Markus J

    2016-02-01

    Optimized for millions of years, natural materials often outperform synthetic materials due to their hierarchical structures and multifunctional abilities. They usually feature a complex architecture that consists of simple building blocks. Indeed, many natural materials such as bone, nacre, hair, and spider silk, have outstanding material properties, making them applicable to engineering applications that may require both mechanical resilience and environmental compatibility. However, such natural materials are very difficult to harvest in bulk, and may be toxic in the way they occur naturally, and therefore, it is critical to use alternative methods to fabricate materials that have material functions similar to material function as their natural counterparts for large-scale applications. Recent progress in additive manufacturing, especially the ability to print multiple materials at upper micrometer resolution, has given researchers an excellent instrument to design and reconstruct natural-inspired materials. The most advanced 3D-printer can now be used to manufacture samples to emulate their geometry and material composition with high fidelity. Its capabilities, in combination with computational modeling, have provided us even more opportunities for designing, optimizing, and testing the function of composite materials, in order to achieve composites of high mechanical resilience and reliability. In this review article, we focus on the advanced material properties of several multifunctional biological materials and discuss how the advanced 3D-printing techniques can be used to mimic their architectures and functions. Lastly, we discuss the limitations of 3D-printing, suggest possible future developments, and discuss applications using bio-inspired materials as a tool in bioengineering and other fields. PMID:26747791

  9. Viscous-Inviscid Methods in Unsteady Aerodynamic Analysis of Bio-Inspired Morphing Wings

    NASA Astrophysics Data System (ADS)

    Dhruv, Akash V.

    Flight has been one of the greatest realizations of human imagination, revolutionizing communication and transportation over the years. This has greatly influenced the growth of technology itself, enabling researchers to communicate and share their ideas more effectively, extending the human potential to create more sophisticated systems. While the end product of a sophisticated technology makes our lives easier, its development process presents an array of challenges in itself. In last decade, scientists and engineers have turned towards bio-inspiration to design more efficient and robust aerodynamic systems to enhance the ability of Unmanned Aerial Vehicles (UAVs) to be operated in cluttered environments, where tight maneuverability and controllability are necessary. Effective use of UAVs in domestic airspace will mark the beginning of a new age in communication and transportation. The design of such complex systems necessitates the need for faster and more effective tools to perform preliminary investigations in design, thereby streamlining the design process. This thesis explores the implementation of numerical panel methods for aerodynamic analysis of bio-inspired morphing wings. Numerical panel methods have been one of the earliest forms of computational methods for aerodynamic analysis to be developed. Although the early editions of this method performed only inviscid analysis, the algorithm has matured over the years as a result of contributions made by prominent aerodynamicists. The method discussed in this thesis is influenced by recent advancements in panel methods and incorporates both viscous and inviscid analysis of multi-flap wings. The surface calculation of aerodynamic coefficients makes this method less computationally expensive than traditional Computational Fluid Dynamics (CFD) solvers available, and thus is effective when both speed and accuracy are desired. The morphing wing design, which consists of sequential feather-like flaps installed

  10. A bio-inspired flying robot sheds light on insect piloting abilities.

    PubMed

    Franceschini, Nicolas; Ruffier, Franck; Serres, Julien

    2007-02-20

    When insects are flying forward, the image of the ground sweeps backward across their ventral viewfield and forms an "optic flow," which depends on both the groundspeed and the groundheight. To explain how these animals manage to avoid the ground by using this visual motion cue, we suggest that insect navigation hinges on a visual-feedback loop we have called the optic-flow regulator, which controls the vertical lift. To test this idea, we built a micro-helicopter equipped with an optic-flow regulator and a bio-inspired optic-flow sensor. This fly-by-sight micro-robot can perform exacting tasks such as take-off, level flight, and landing. Our control scheme accounts for many hitherto unexplained findings published during the last 70 years on insects' visually guided performances; for example, it accounts for the fact that honeybees descend in a headwind, land with a constant slope, and drown when travelling over mirror-smooth water. Our control scheme explains how insects manage to fly safely without any of the instruments used onboard aircraft to measure the groundheight, groundspeed, and descent speed. An optic-flow regulator is quite simple in terms of its neural implementation and just as appropriate for insects as it would be for aircraft. PMID:17291757

  11. A bio-inspired shape memory alloy composite (BISMAC) actuator

    NASA Astrophysics Data System (ADS)

    Villanueva, A. A.; Joshi, K. B.; Blottman, J. B.; Priya, S.

    2010-02-01

    A beam-shape composite actuator using shape memory alloy (SMA) wires as the active component, termed a Bio-Inspired Shape Memory Alloy Composite (BISMAC), was designed to provide a large deformation profile. The BISMAC design was inspired by contraction of a jellyfish bell, utilizing the rowing mechanism for locomotion. Characterization of maximum deformation in underwater conditions was performed for different actuator configurations to analyze the effect of different design parameters, including silicone thickness, flexible steel thickness and distance between the SMA and flexible steel. A constant cross-section (CC)-BISMAC of length 16 cm was found to achieve deformation with a radius of curvature of 3.5 cm. Under equilibrium conditions, the CC-BISMAC was found to achieve 80% of maximum deformation, consuming 7.9 J/cycle driven at 16.2 V/0.98 A and a frequency of 0.25 Hz. A detailed analytical model was developed using the transfer matrix method and a 1D finite beam element (FE) model to simulate the behavior of the BISMAC incorporating gravity, buoyancy and SMA parameters. The FE and transfer matrix models had a maximum deformation error norm of 1.505 and 1.917 cm in comparison with experimentally observed beam deformation in the CC-BISMAC. The mean curvatures predicted by the FE and transfer matrix methods were 0.292 cm-1 and 0.295 cm-1 compared to a mean experimental curvature of 0.294 cm-1, a percentage error of -5.4% and 2.77%, respectively. Using the developed analytical model, an actuator design was fabricated mimicking the maximum deformation profile of jellyfish of the species Aurelia aurita (AA). The designed AA-BISMAC achieved a maximum curvature of 0.428 cm-1 as compared to 0.438 cm-1 for A. aurita with an average square root error of 0.043 cm-1, 10.2% of maximum A. aurita curvature.

  12. Bio-Inspired Approaches to Crystals with Composite Structures

    NASA Astrophysics Data System (ADS)

    Meldrum, Fiona

    2013-03-01

    Advances in technology demand an ever-increasing degree of control over material structure, properties and function. As the properties of monolithic materials are necessary limited, one route to extending them is to create a composite by combining contrasting materials. The potential of this approach is beautifully illustrated by the formation of biominerals where organic macromolecules are combined with brittle minerals such as calcite to create crystals with considerable fracture toughness. This talk will discuss how bio-inspired approaches can be used to generate single crystals with composite crystals through a simple one-pot method. By precipitating calcite crystals in the presence of ``occlusion species'' ranging from latex particles, to organic and inorganic nanoparticles and finally small molecules we demonstrate that high amounts of foreign species can be incorporated through control over the additive surface chemistry, and that this can lead to an enhancement of the mechanical properties of the calcite. Occlusion of 20 nm anionic diblock copolymer micelles was achieved at levels of over 13 wt%, and the properties of the resuktant composite calcite crystals were measured using a range of techniques including IR spectroscopy, high resolution powder XRD and high resolution TEM. Incorporation of these macromolecules leads to crystals with structures and mechanical properties similar to those of biominerals. With sizes in the range of some intracrystalline proteins, the micelles act as ``pseudo-proteins'', thereby providing an excellent model system for investigation of the mechanism of macromolecule insertion within biominerals. Extension of these studies to the incorporation of small molecules (amino acids) again demonstrated high levels of incorporation without any change in the crystal morphology. Further, occlusion of these small molecules within the calcite lattice again resulted in a significant increase in the hardness of the calcite, a result which

  13. Bio-inspired Nanomaterials for Biosensing and Cell Response

    NASA Astrophysics Data System (ADS)

    Stevens, Molly

    2012-02-01

    This talk will provide an overview of our recent developments in bio-inspired nanomaterials for tissue regeneration and sensing. Bio-responsive nanomaterials are of growing importance with potential applications including drug delivery, diagnostics and tissue engineering [1]. DNA-, protein- or peptide-functionalised nanoparticle (NP) aggregates are particularly useful systems since triggered changes in their aggregation states may be readily monitored. Our recent simple conceptually novel approaches to real-time monitoring of protease, lipase and kinase enzyme action using modular peptide functionalized NPs will be presented [2,3,4]. The highly interdisciplinary field of Tissue Engineering (TE) can also benefit from advances in the design of bio-responsive nanomaterials. TE involves the development of artificial scaffold structures on which new cells are encouraged to grow. The ability to control topography and chemistry at the nanoscale offers exciting possibilities for stimulating growth of new tissue through the development of novel nanostructured scaffolds that mimic the nanostructure of the tissues in the body [1,5,6]. Recent developments in this context will be discussed as well as novel approaches to in vivo tissue regeneration of large volumes of highly vascularised and hierarchically organized tissue [7,8,9]. [4pt] [1] MM Stevens, J George. Science 310:1135-1138 (2005)[0pt] [2] A Laromaine, L Koh, M Murugesan, RV Ulijn, MM Stevens. Journal of the American Chemical Society 129:4156-4157 (2007)[0pt] [3] J Ghadiali, MM Stevens. Advanced Materials 20: 4359-4363 (2008); J Ghadiali et al, ACS Nano 4:4915-4919 (2010)[0pt] [4] D Aili, M Mager, D Roche, MM Stevens. Nano Letters 11:1401-1405 (2011) [0pt] [5] E Place, ND Evans, MM Stevens. Nature Materials 8:457-470 (2009)[0pt] [6] MD Mager, V LaPointe, MM Stevens. Nature Chemistry 3:582-589 (2011)[0pt] [7] MM Stevens et. al. Proc. Natl. Acad. Sci. USA 102:11450-11455 (2005)[0pt] [8] E Gentleman et al. Nature

  14. Bio-inspired 3D microenvironments: a new dimension in tissue engineering.

    PubMed

    Magin, Chelsea M; Alge, Daniel L; Anseth, Kristi S

    2016-04-01

    Biomaterial scaffolds have been a foundational element of the tissue engineering paradigm since the inception of the field. Over the years there has been a progressive move toward the rational design and fabrication of bio-inspired materials that mimic the composition as well as the architecture and 3D structure of tissues. In this review, we chronicle advances in the field that address key challenges in tissue engineering as well as some emerging applications. Specifically, a summary of the materials and chemistries used to engineer bio-inspired 3D matrices that mimic numerous aspects of the extracellular matrix is provided, along with an overview of bioprinting, an additive manufacturing approach, for the fabrication of engineered tissues with precisely controlled 3D structures and architectures. To emphasize the potential clinical impact of the bio-inspired paradigm in biomaterials engineering, some applications of bio-inspired matrices are discussed in the context of translational tissue engineering. However, focus is also given to recent advances in the use of engineered 3D cellular microenvironments for fundamental studies in cell biology, including photoresponsive systems that are shedding new light on how matrix properties influence cell phenotype and function. In an outlook for future work, the need for high-throughput methods both for screening and fabrication is highlighted. Finally, microscale organ-on-a-chip technologies are highlighted as a promising area for future investment in the application of bio-inspired microenvironments. PMID:26942469

  15. Bio-inspired patterned networks (BIPS) for development of wearable/disposable biosensors

    NASA Astrophysics Data System (ADS)

    McLamore, E. S.; Convertino, M.; Hondred, John; Das, Suprem; Claussen, J. C.; Vanegas, D. C.; Gomes, C.

    2016-05-01

    Here we demonstrate a novel approach for fabricating point of care (POC) wearable electrochemical biosensors based on 3D patterning of bionanocomposite networks. To create Bio-Inspired Patterned network (BIPS) electrodes, we first generate fractal network in silico models that optimize transport of network fluxes according to an energy function. Network patterns are then inkjet printed onto flexible substrate using conductive graphene ink. We then deposit fractal nanometal structures onto the graphene to create a 3D nanocomposite network. Finally, we biofunctionalize the surface with biorecognition agents using covalent bonding. In this paper, BIPS are used to develop high efficiency, low cost biosensors for measuring glucose as a proof of concept. Our results on the fundamental performance of BIPS sensors show that the biomimetic nanostructures significantly enhance biosensor sensitivity, accuracy, response time, limit of detection, and hysteresis compared to conventional POC non fractal electrodes (serpentine, interdigitated, and screen printed electrodes). BIPs, in particular Apollonian patterned BIPS, represent a new generation of POC biosensors based on nanoscale and microscale fractal networks that significantly improve electrical connectivity, leading to enhanced sensor performance.

  16. A bio-inspired swarm robot coordination algorithm for multiple target searching

    NASA Astrophysics Data System (ADS)

    Meng, Yan; Gan, Jing; Desai, Sachi

    2008-04-01

    The coordination of a multi-robot system searching for multi targets is challenging under dynamic environment since the multi-robot system demands group coherence (agents need to have the incentive to work together faithfully) and group competence (agents need to know how to work together well). In our previous proposed bio-inspired coordination method, Local Interaction through Virtual Stigmergy (LIVS), one problem is the considerable randomness of the robot movement during coordination, which may lead to more power consumption and longer searching time. To address these issues, an adaptive LIVS (ALIVS) method is proposed in this paper, which not only considers the travel cost and target weight, but also predicting the target/robot ratio and potential robot redundancy with respect to the detected targets. Furthermore, a dynamic weight adjustment is also applied to improve the searching performance. This new method a truly distributed method where each robot makes its own decision based on its local sensing information and the information from its neighbors. Basically, each robot only communicates with its neighbors through a virtual stigmergy mechanism and makes its local movement decision based on a Particle Swarm Optimization (PSO) algorithm. The proposed ALIVS algorithm has been implemented on the embodied robot simulator, Player/Stage, in a searching target. The simulation results demonstrate the efficiency and robustness in a power-efficient manner with the real-world constraints.

  17. A bio-inspired stimulator to desynchronize epileptic cortical population models: A digital implementation framework.

    PubMed

    Piri, Mohsen; Amiri, Masoud; Amiri, Mahmood

    2015-07-01

    Pathophysiologic neural synchronization is a hallmark of several neurological disorders such as epilepsy. In addition, based on established neurophysiologic findings, astrocytes dynamically regulate the synaptic transmission and have key roles in stabilizing neural synchronization. Therefore, in the present study, based on the dynamic model of astrocyte, a digital bio-inspired stimulator is proposed to avoid the hyper-synchronous seizure-like activities in a cortical population model. The complete digital circuit of the close loop system that is the bio-inspired stimulator and the cortical population model are implemented in hardware on the ZedBoard development kit. Based on the results of MATLAB simulations, hardware synthesis and FPGA implementation, it is demonstrated that the digital bio-inspired stimulator can effectively prevent the occurrence of spontaneous paroxysmal episodes with a demand-controlled characteristic. In this way, the designed digital stimulator successfully maintains the normal ongoing activity. PMID:25888932

  18. Architecture for persistent surveillance using mast and UAS-based autonomous sensing with bio-inspired technologies

    NASA Astrophysics Data System (ADS)

    Burman, Jerry

    2014-06-01

    A sophisticated real time architecture for capturing relevant battlefield information of personnel and terrestrial events from a network of mast based imaging and unmanned aerial systems (UAS) with target detection, tracking, classification and visualization is presented. Persistent surveillance of personnel and vehicles is achieved using a unique spatial and temporally invariant motion detection and tracking algorithm for mast based cameras in combination with aerial remote sensing to autonomously monitor unattended ground based sensor networks. UAS autonomous routing is achieved using bio-inspired algorithms that mimic how bacteria locate nutrients in their environment. Results include field test data, performance and lessons learned. The technology also has application to detecting and tracking low observables (manned and UAS), counter MANPADS, airport bird detection and search and rescue operations.

  19. Bio-Inspired Metal-Coordination Dynamics: A Unique Tool for Engineering Soft Matter Mechanics

    NASA Astrophysics Data System (ADS)

    Holten-Andersen, Niels

    Growing evidence supports a critical role of metal-coordination in soft biological material properties such as self-healing, underwater adhesion and autonomous wound plugging. Using bio-inspired metal-binding polymers, initial efforts to mimic these properties with metal-coordination crosslinked polymer materials have shown promise. In addition, with polymer network mechanics strongly coupled to coordinate crosslink dynamics material properties can be easily tuned from visco-elastic fluids to solids. Given their exploitation in desirable material applications in Nature, bio-inspired metal-coordinate complex crosslinking provides an opportunity to further advance synthetic polymer materials design. Early lessons from this pursuit are presented.

  20. Development of a bio-inspired UAV perching system

    NASA Astrophysics Data System (ADS)

    Xie, Pu

    of animals and human arms approaching to a fixed or moving target for grasping or capturing. The autonomous flight control was also implemented through a PID controller. Autonomous flight performance was proved through simulation in SimMechanics. Finally, the prototyping of our designs were conducted in different generations of our bio-inspired UAV perching system, which include the leg prototype, gripper prototype, and system prototype. Both the machined prototype and 3D printed prototype were tried. The performance of these prototypes was tested through experiments.

  1. A two-dimensional iterative panel method and boundary layer model for bio-inspired multi-body wings

    NASA Astrophysics Data System (ADS)

    Blower, Christopher J.; Dhruv, Akash; Wickenheiser, Adam M.

    2014-03-01

    The increased use of Unmanned Aerial Vehicles (UAVs) has created a continuous demand for improved flight capabilities and range of use. During the last decade, engineers have turned to bio-inspiration for new and innovative flow control methods for gust alleviation, maneuverability, and stability improvement using morphing aircraft wings. The bio-inspired wing design considered in this study mimics the flow manipulation techniques performed by birds to extend the operating envelope of UAVs through the installation of an array of feather-like panels across the airfoil's upper and lower surfaces while replacing the trailing edge flap. Each flap has the ability to deflect into both the airfoil and the inbound airflow using hinge points with a single degree-of-freedom, situated at 20%, 40%, 60% and 80% of the chord. The installation of the surface flaps offers configurations that enable advantageous maneuvers while alleviating gust disturbances. Due to the number of possible permutations available for the flap configurations, an iterative constant-strength doublet/source panel method has been developed with an integrated boundary layer model to calculate the pressure distribution and viscous drag over the wing's surface. As a result, the lift, drag and moment coefficients for each airfoil configuration can be calculated. The flight coefficients of this numerical method are validated using experimental data from a low speed suction wind tunnel operating at a Reynolds Number 300,000. This method enables the aerodynamic assessment of a morphing wing profile to be performed accurately and efficiently in comparison to Computational Fluid Dynamics methods and experiments as discussed herein.

  2. Bio-inspired robot design for viscous fluids

    NASA Astrophysics Data System (ADS)

    Ma, Grace; Lipman, Tyler; Jung, Sunghwan

    Many modern micro-robots are designed for biomedical applications to transport drugs to targets or to operate tests in the body for diagnosis. However, most micro-robots simply mimic the morphology and the propulsive mechanism of micro-organisms without understanding the underlying physics of low-Re swimming. Two types of swimming motions have been observed in micro-organisms; stresslet and source-dipole swimming. The stresslet swimmer (e.g. E. coli) uses a rotating helical appendage, whereas the source-dipole swimmer (e.g. Paramecium) creates surface velocity for propulsion. Using this principle, we designed a robot to swim in very viscous fluids either by rotating a helix or creating surface velocity, simply by changing the orientation of the appendage. Further, we will discuss the performance of this robot (swimming speed and rotation speed) with respect to the number, winding angle, and radius of helices in a very viscous fluid.

  3. High Speed Edge Detection

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F (Inventor)

    2016-01-01

    Analog circuits for detecting edges in pixel arrays are disclosed. A comparator may be configured to receive an all pass signal and a low pass signal for a pixel intensity in an array of pixels. A latch may be configured to receive a counter signal and a latching signal from the comparator. The comparator may be configured to send the latching signal to the latch when the all pass signal is below the low pass signal minus an offset. The latch may be configured to hold a last negative edge location when the latching signal is received from the comparator.

  4. High Speed Edge Detection

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F (Inventor)

    2015-01-01

    Analog circuits for detecting edges in pixel arrays are disclosed. A comparator may be configured to receive an all pass signal and a low pass signal for a pixel intensity in an array of pixels. A latch may be configured to receive a counter signal and a latching signal from the comparator. The comparator may be configured to send the latching signal to the latch when the all pass signal is below the low pass signal minus an offset. The latch may be configured to hold a last negative edge location when the latching signal is received from the comparator.

  5. Multibody system dynamics for bio-inspired locomotion: from geometric structures to computational aspects.

    PubMed

    Boyer, Frédéric; Porez, Mathieu

    2015-04-01

    This article presents a set of generic tools for multibody system dynamics devoted to the study of bio-inspired locomotion in robotics. First, archetypal examples from the field of bio-inspired robot locomotion are presented to prepare the ground for further discussion. The general problem of locomotion is then stated. In considering this problem, we progressively draw a unified geometric picture of locomotion dynamics. For that purpose, we start from the model of discrete mobile multibody systems (MMSs) that we progressively extend to the case of continuous and finally soft systems. Beyond these theoretical aspects, we address the practical problem of the efficient computation of these models by proposing a Newton-Euler-based approach to efficient locomotion dynamics with a few illustrations of creeping, swimming, and flying. PMID:25811531

  6. Overcoming the brittleness of glass through bio-inspiration and micro-architecture

    NASA Astrophysics Data System (ADS)

    Mirkhalaf, M.; Dastjerdi, A. Khayer; Barthelat, F.

    2014-01-01

    Highly mineralized natural materials such as teeth or mollusk shells boast unusual combinations of stiffness, strength and toughness currently unmatched by engineering materials. While high mineral contents provide stiffness and hardness, these materials also contain weaker interfaces with intricate architectures, which can channel propagating cracks into toughening configurations. Here we report the implementation of these features into glass, using a laser engraving technique. Three-dimensional arrays of laser-generated microcracks can deflect and guide larger incoming cracks, following the concept of ‘stamp holes’. Jigsaw-like interfaces, infiltrated with polyurethane, furthermore channel cracks into interlocking configurations and pullout mechanisms, significantly enhancing energy dissipation and toughness. Compared with standard glass, which has no microstructure and is brittle, our bio-inspired glass displays built-in mechanisms that make it more deformable and 200 times tougher. This bio-inspired approach, based on carefully architectured interfaces, provides a new pathway to toughening glasses, ceramics or other hard and brittle materials.

  7. On-chip visual perception of motion: a bio-inspired connectionist model on FPGA.

    PubMed

    Torres-Huitzil, César; Girau, Bernard; Castellanos-Sánchez, Claudio

    2005-01-01

    Visual motion provides useful information to understand the dynamics of a scene to allow intelligent systems interact with their environment. Motion computation is usually restricted by real time requirements that need the design and implementation of specific hardware architectures. In this paper, the design of hardware architecture for a bio-inspired neural model for motion estimation is presented. The motion estimation is based on a strongly localized bio-inspired connectionist model with a particular adaptation of spatio-temporal Gabor-like filtering. The architecture is constituted by three main modules that perform spatial, temporal, and excitatory-inhibitory connectionist processing. The biomimetic architecture is modeled, simulated and validated in VHDL. The synthesis results on a Field Programmable Gate Array (FPGA) device show the potential achievement of real-time performance at an affordable silicon area. PMID:16102939

  8. A bio-inspired apposition compound eye machine vision sensor system.

    PubMed

    Davis, J D; Barrett, S F; Wright, C H G; Wilcox, M

    2009-12-01

    The Wyoming Information, Signal Processing, and Robotics Laboratory is developing a wide variety of bio-inspired vision sensors. We are interested in exploring the vision system of various insects and adapting some of their features toward the development of specialized vision sensors. We do not attempt to supplant traditional digital imaging techniques but rather develop sensor systems tailor made for the application at hand. We envision that many applications may require a hybrid approach using conventional digital imaging techniques enhanced with bio-inspired analogue sensors. In this specific project, we investigated the apposition compound eye and its characteristics commonly found in diurnal insects and certain species of arthropods. We developed and characterized an array of apposition compound eye-type sensors and tested them on an autonomous robotic vehicle. The robot exhibits the ability to follow a pre-defined target and avoid specified obstacles using a simple control algorithm. PMID:19901450

  9. Bio-inspired microfluidics: The case of the velvet worm

    NASA Astrophysics Data System (ADS)

    Concha, Andres; Mellado, Paula; Morera-Brenes, Bernal; Sampaio-Costa, Cristiano; Mahadevan, L.; Monge-Najera, Julian

    The rapid squirt of a proteinaceous slime jet endow velvet worms (Onychophora) with a unique mechanism for defense from predators and for capturing prey by entangling them in a disordered web that immobilizes their target. However, to date neither qualitative nor quantitative descriptions have been provided for this unique adaptation. We have investigated the mechanism that allows velvet worms the fast oscillatory motion of their oral papillae and the exiting liquid jet that oscillates with frequencies f ~ 30 - 60 Hz. Using anatomical images and high speed videography, we show that even without fast muscular action of the papilla, a strong contraction of the slime reservoir and the geometry of the reservoir-papilla system suffices to accelerate the slime to speeds up to v ~ 5 m /s in about Δt ~ 60 ms. A theoretical analysis and a physical simulacrum allow us to infer that this fast oscillatory motion is the result of an elastohydrodynamic instability driven by the interplay between the elasticity of oral papillae and the fast unsteady flow during squirting. We propose several applications that can be implemented using this instability, ranging from high-throughput droplet production, printing, and micro-nanofiber production among others. A.C was partially supported by Fondecyt Grant 11130075.

  10. Bio-Inspired Controller on an FPGA Applied to Closed-Loop Diaphragmatic Stimulation

    PubMed Central

    Zbrzeski, Adeline; Bornat, Yannick; Hillen, Brian; Siu, Ricardo; Abbas, James; Jung, Ranu; Renaud, Sylvie

    2016-01-01

    Cervical spinal cord injury can disrupt connections between the brain respiratory network and the respiratory muscles which can lead to partial or complete loss of ventilatory control and require ventilatory assistance. Unlike current open-loop technology, a closed-loop diaphragmatic pacing system could overcome the drawbacks of manual titration as well as respond to changing ventilation requirements. We present an original bio-inspired assistive technology for real-time ventilation assistance, implemented in a digital configurable Field Programmable Gate Array (FPGA). The bio-inspired controller, which is a spiking neural network (SNN) inspired by the medullary respiratory network, is as robust as a classic controller while having a flexible, low-power and low-cost hardware design. The system was simulated in MATLAB with FPGA-specific constraints and tested with a computational model of rat breathing; the model reproduced experimentally collected respiratory data in eupneic animals. The open-loop version of the bio-inspired controller was implemented on the FPGA. Electrical test bench characterizations confirmed the system functionality. Open and closed-loop paradigm simulations were simulated to test the FPGA system real-time behavior using the rat computational model. The closed-loop system monitors breathing and changes in respiratory demands to drive diaphragmatic stimulation. The simulated results inform future acute animal experiments and constitute the first step toward the development of a neuromorphic, adaptive, compact, low-power, implantable device. The bio-inspired hardware design optimizes the FPGA resource and time costs while harnessing the computational power of spike-based neuromorphic hardware. Its real-time feature makes it suitable for in vivo applications. PMID:27378844

  11. Bio-Inspired Controller on an FPGA Applied to Closed-Loop Diaphragmatic Stimulation.

    PubMed

    Zbrzeski, Adeline; Bornat, Yannick; Hillen, Brian; Siu, Ricardo; Abbas, James; Jung, Ranu; Renaud, Sylvie

    2016-01-01

    Cervical spinal cord injury can disrupt connections between the brain respiratory network and the respiratory muscles which can lead to partial or complete loss of ventilatory control and require ventilatory assistance. Unlike current open-loop technology, a closed-loop diaphragmatic pacing system could overcome the drawbacks of manual titration as well as respond to changing ventilation requirements. We present an original bio-inspired assistive technology for real-time ventilation assistance, implemented in a digital configurable Field Programmable Gate Array (FPGA). The bio-inspired controller, which is a spiking neural network (SNN) inspired by the medullary respiratory network, is as robust as a classic controller while having a flexible, low-power and low-cost hardware design. The system was simulated in MATLAB with FPGA-specific constraints and tested with a computational model of rat breathing; the model reproduced experimentally collected respiratory data in eupneic animals. The open-loop version of the bio-inspired controller was implemented on the FPGA. Electrical test bench characterizations confirmed the system functionality. Open and closed-loop paradigm simulations were simulated to test the FPGA system real-time behavior using the rat computational model. The closed-loop system monitors breathing and changes in respiratory demands to drive diaphragmatic stimulation. The simulated results inform future acute animal experiments and constitute the first step toward the development of a neuromorphic, adaptive, compact, low-power, implantable device. The bio-inspired hardware design optimizes the FPGA resource and time costs while harnessing the computational power of spike-based neuromorphic hardware. Its real-time feature makes it suitable for in vivo applications. PMID:27378844

  12. Cochlear outer hair cell bio-inspired metamaterial with negative effective parameters

    NASA Astrophysics Data System (ADS)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Zhang, Siwen

    2016-05-01

    Inspired by periodical outer hair cells (OHCs) and stereocilia clusters of mammalian cochlear, a type of bio-inspired metamaterial with negative effective parameters based on the OHC structure is proposed. With the structural parameters modified and some common engineering materials adopted, the bio-inspired structure design with length scales of millimeter and lightweight is presented, and then, a bending wave bandgap in a favorable low-frequency with width of 55 Hz during the interval 21-76 or 116 Hz during the interval 57-173 Hz is obtained, i.e., the excellent low-frequency acoustic performance turns up. Compared with the local resonance unit in previous literatures, both the size and weight are greatly reduced in our bio-inspired structure. In addition, the lower edge of low-frequency bandgap is reduced by an order of magnitude, almost to the lower limit frequency of the hearing threshold as well, which achieves an important breakthrough on the aspect of low-frequency and great significance on the noise and vibration reduction in low-frequency range.

  13. Parameter estimation with bio-inspired meta-heuristic optimization: modeling the dynamics of endocytosis

    PubMed Central

    2011-01-01

    results hold for both real and artificial data, for all observability scenarios considered, and for all amounts of noise added to the artificial data. In sum, the meta-heuristic methods considered are suitable for estimating the parameters in the ODE model of the dynamics of endocytosis under a range of conditions: With the model and conditions being representative of parameter estimation tasks in ODE models of biochemical systems, our results clearly highlight the promise of bio-inspired meta-heuristic methods for parameter estimation in dynamic system models within system biology. PMID:21989196

  14. Bio-Inspired Neural Model for Learning Dynamic Models

    NASA Technical Reports Server (NTRS)

    Duong, Tuan; Duong, Vu; Suri, Ronald

    2009-01-01

    A neural-network mathematical model that, relative to prior such models, places greater emphasis on some of the temporal aspects of real neural physical processes, has been proposed as a basis for massively parallel, distributed algorithms that learn dynamic models of possibly complex external processes by means of learning rules that are local in space and time. The algorithms could be made to perform such functions as recognition and prediction of words in speech and of objects depicted in video images. The approach embodied in this model is said to be "hardware-friendly" in the following sense: The algorithms would be amenable to execution by special-purpose computers implemented as very-large-scale integrated (VLSI) circuits that would operate at relatively high speeds and low power demands.

  15. Bio-inspired nanocomposite assemblies as smart skin components.

    SciTech Connect

    Montano, Gabriel A.; Xiao, Xiaoyin; Achyuthan, Komandoor E.; Allen, Amy; Brozik, Susan Marie; Edwards, Thayne L.; Frischknecht, Amalie Lucile; Wheeler, David Roger

    2011-09-01

    There is national interest in the development of sophisticated materials that can automatically detect and respond to chemical and biological threats without the need for human intervention. In living systems, cell membranes perform such functions on a routine basis, detecting threats, communicating with the cell, and triggering automatic responses such as the opening and closing of ion channels. The purpose of this project was to learn how to replicate simple threat detection and response functions within artificial membrane systems. The original goals toward developing 'smart skin' assemblies included: (1) synthesizing functionalized nanoparticles to produce electrochemically responsive systems within a lipid bilayer host matrices, (2) calculating the energetics of nanoparticle-lipid interactions and pore formation, and (3) determining the mechanism of insertion of nanoparticles in lipid bilayers via imaging and electrochemistry. There are a few reports of the use of programmable materials to open and close pores in rigid hosts such as mesoporous materials using either heat or light activation. However, none of these materials can regulate themselves in response to the detection of threats. The strategies we investigated in this project involve learning how to use programmable nanomaterials to automatically eliminate open channels within a lipid bilayer host when 'threats' are detected. We generated and characterized functionalized nanoparticles that can be used to create synthetic pores through the membrane and investigated methods of eliminating the pores either through electrochemistry, change in pH, etc. We also focused on characterizing the behavior of functionalized gold NPs in different lipid membranes and lipid vesicles and coupled these results to modeling efforts designed to gain an understanding of the interaction of nanoparticles within lipid assemblies.

  16. Bio-Inspired Green Nanoparticles: Synthesis, Mechanism, and Antibacterial Application

    PubMed Central

    Velusamy, Palaniyandi; Kumar, Govindarajan Venkat; Jeyanthi, Venkadapathi; Das, Jayabrata; Pachaiappan, Raman

    2016-01-01

    In the recent years, noble nanoparticles have attracted and emerged in the field of biology, medicine and electronics due to their incredible applications. There were several methods have been used for synthesis of nanoparticles such as toxic chemicals and high energy physical procedures. To overcome these, biological method has been used for the synthesis of various metal nanoparticles. Among the nanoparticles, silver nanoparticles (AgNPs) have received much attention in various fields, such as antimicrobial activity, therapeutics, bio-molecular detection, silver nanocoated medical devices and optical receptor. Moreover, the biological approach, in particular the usage of natural organisms has offered a reliable, simple, nontoxic and environmental friendly method. Hence, the current article is focused on the biological synthesis of silver nanoparticles and their application in the biomedical field. PMID:27123159

  17. Bio-inspired nano-sensor-enhanced CNN visual computer.

    PubMed

    Porod, Wolfgang; Werblin, Frank; Chua, Leon O; Roska, Tamas; Rodriguez-Vazquez, Angel; Roska, Botond; Fay, Patrick; Bernstein, Gary H; Huang, Yih-Fang; Csurgay, Arpad I

    2004-05-01

    Nanotechnology opens new ways to utilize recent discoveries in biological image processing by translating the underlying functional concepts into the design of CNN (cellular neural/nonlinear network)-based systems incorporating nanoelectronic devices. There is a natural intersection joining studies of retinal processing, spatio-temporal nonlinear dynamics embodied in CNN, and the possibility of miniaturizing the technology through nanotechnology. This intersection serves as the springboard for our multidisciplinary project. Biological feature and motion detectors map directly into the spatio-temporal dynamics of CNN for target recognition, image stabilization, and tracking. The neural interactions underlying color processing will drive the development of nanoscale multispectral sensor arrays for image fusion. Implementing such nanoscale sensors on a CNN platform will allow the implementation of device feedback control, a hallmark of biological sensory systems. These biologically inspired CNN subroutines are incorporated into the new world of analog-and-logic algorithms and software, containing also many other active-wave computing mechanisms, including nature-inspired (physics and chemistry) as well as PDE-based sophisticated spatio-temporal algorithms. Our goal is to design and develop several miniature prototype devices for target detection, navigation, tracking, and robotics. This paper presents an example illustrating the synergies emerging from the convergence of nanotechnology, biotechnology, and information and cognitive science. PMID:15194609

  18. Biomimetic and bio-inspired robotics in electric fish research.

    PubMed

    Neveln, Izaak D; Bai, Yang; Snyder, James B; Solberg, James R; Curet, Oscar M; Lynch, Kevin M; MacIver, Malcolm A

    2013-07-01

    Weakly electric knifefish have intrigued both biologists and engineers for decades with their unique electrosensory system and agile swimming mechanics. Study of these fish has resulted in models that illuminate the principles behind their electrosensory system and unique swimming abilities. These models have uncovered the mechanisms by which knifefish generate thrust for swimming forward and backward, hovering, and heaving dorsally using a ventral elongated median fin. Engineered active electrosensory models inspired by electric fish allow for close-range sensing in turbid waters where other sensing modalities fail. Artificial electrosense is capable of aiding navigation, detection and discrimination of objects, and mapping the environment, all tasks for which the fish use electrosense extensively. While robotic ribbon fin and artificial electrosense research has been pursued separately to reduce complications that arise when they are combined, electric fish have succeeded in their ecological niche through close coupling of their sensing and mechanical systems. Future integration of electrosense and ribbon fin technology into a knifefish robot should likewise result in a vehicle capable of navigating complex 3D geometries unreachable with current underwater vehicles, as well as provide insights into how to design mobile robots that integrate high bandwidth sensing with highly responsive multidirectional movement. PMID:23761475

  19. BATMAV: a 2-DOF bio-inspired flapping flight platform

    NASA Astrophysics Data System (ADS)

    Bunget, Gheorghe; Seelecke, Stefan

    2010-04-01

    Due to the availability of small sensors, Micro-Aerial Vehicles (MAVs) can be used for detection missions of biological, chemical and nuclear agents. Traditionally these devices used fixed or rotary wings, actuated with electric DC motortransmission, a system which brings the disadvantage of a heavier platform. The overall objective of the BATMAV project is to develop a biologically inspired bat-like MAV with flexible and foldable wings for flapping flight. This paper presents a flight platform that features bat-inspired wings which are able to actively fold their elbow joints. A previous analysis of the flight physics for small birds, bats and large insects, revealed that the mammalian flight anatomy represents a suitable flight platform that can be actuated efficiently using Shape Memory Alloy (SMA) artificial-muscles. A previous study of the flight styles in bats based on the data collected by Norberg [1] helped to identify the required joint angles as relevant degrees of freedom for wing actuation. Using the engineering theory of robotic manipulators, engineering kinematic models of wings with 2 and 3-DOFs were designed to mimic the wing trajectories of the natural flier Plecotus auritus. Solid models of the bat-like skeleton were designed based on the linear and angular dimensions resulted from the kinematic models. This structure of the flight platform was fabricated using rapid prototyping technologies and assembled to form a desktop prototype with 2-DOFs wings. Preliminary flapping test showed suitable trajectories for wrist and wingtip that mimic the flapping cycle of the natural flyer.

  20. Bio-inspired synthesis of ZnO polyhedral single crystals under eggshell membrane direction

    NASA Astrophysics Data System (ADS)

    Su, Huilan; Song, Fang; Dong, Qun; Li, Tuoqi; Zhang, Xin; Zhang, Di

    2011-07-01

    A simple and versatile technique was developed to prepare hierarchical ZnO single crystals by introducing eggshell membrane (ESM) to a bio-inspired approach. Based on the control of nucleation and gestation, ZnO nanocrystallites could grow at three dimensions into polyhedral single crystals through a surface sol-gel process followed by a calcination treatment. Different from traditional wet chemical techniques, our synthetic process depends more on the restrictive or directing functions of the ESM biomacromolecules. The hierarchical ZnO nanostructures doped with polyhedral single crystallites could be desirable for catalysts, photoelectrochemical devices, especially solar cells.

  1. Facile creation of bio-inspired superhydrophobic Ce-based metallic glass surfaces

    SciTech Connect

    Liu Kesong; Li Zhou; Wang Weihua; Jiang Lei

    2011-12-26

    A bio-inspired synthesis strategy was conducted to fabricate superhydrophobic Ce-based bulk metallic glass (BMG) surfaces with self-cleaning properties. Micro-nanoscale hierarchical structures were first constructed on BMG surfaces and then modified with the low surface energy coating. Surface structures, surface chemical compositions, and wettability were characterized by combining scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and contact angle measurements. Research indicated that both surface multiscale structures and the low surface free energy coating result in the final formation of superhydrophobicity.

  2. Bio-inspired artificial iridophores based on capillary origami: Fabrication and device characterization

    NASA Astrophysics Data System (ADS)

    Manakasettharn, Supone; Ashley Taylor, J.; Krupenkin, Tom N.

    2011-10-01

    Cephalopods have evolved complex optical mechanisms of dynamic skin color control based on mechanical actuation of micro-scale optical structures such as iridophores and chromatophores. In this work, we describe the design, fabrication, and characterization of bio-inspired artificial iridophores, which resemble microflowers with flexible reflective petals, based on capillary origami microstructures. Two methods of petal actuation have been demonstrated—one based on the electrowetting process and the other by volume change of the liquid droplet. These results were in good agreement with a model derived to characterize the actuation dynamics.

  3. A bio-inspired approach for in situ synthesis of tunable adhesive.

    PubMed

    Sun, Leming; Yi, Sijia; Wang, Yongzhong; Pan, Kang; Zhong, Qixin; Zhang, Mingjun

    2014-03-01

    Inspired by the strong adhesive produced by English ivy, this paper proposes an in situ synthesis approach for fabricating tunable nanoparticle enhanced adhesives. Special attention was given to tunable features of the adhesive produced by the biological process. Parameters that may be used to tune properties of the adhesive will be proposed. To illustrate and validate the proposed approach, an experimental platform was presented for fabricating tunable chitosan adhesive enhanced by Au nanoparticles synthesized in situ. This study contributes to a bio-inspired approach for in situ synthesis of tunable nanocomposite adhesives by mimicking the natural biological processes of ivy adhesive synthesis. PMID:24343277

  4. Guided extracellular matrix formation from fibroblast cells cultured on bio-inspired configurable multiscale substrata

    PubMed Central

    Bae, Won-Gyu; Kim, Jangho; Choung, Yun-Hoon; Chung, Yesol; Suh, Kahp Y.; Pang, Changhyun; Chung, Jong Hoon; Jeong, Hoon Eui

    2015-01-01

    Engineering complex extracellular matrix (ECM) is an important challenge for cell and tissue engineering applications as well as for understanding fundamental cell biology. We developed the methodology for fabrication of precisely controllable multiscale hierarchical structures using capillary force lithography in combination with original wrinkling technique for the generation of well-defined native ECM-like platforms by culturing fibroblast cells on the multiscale substrata [1]. This paper provides information on detailed characteristics of polyethylene glycol-diacrylate multiscale substrata. In addition, a possible model for guided extracellular matrix formation from fibroblast cells cultured on bio-inspired configurable multiscale substrata is proposed. PMID:26543882

  5. A new bio-inspired route to metal-nanoparticle-based heterogeneous catalysts.

    PubMed

    Debecker, Damien P; Faure, Chrystel; Meyre, Marie-Edith; Derré, Alain; Gaigneaux, Eric M

    2008-10-01

    Onion-type multilamellar vesicles are made of concentric bilayers of organic surfactant and are mainly known for their potential applications in biotechnology. They can be used as microreactors for the spontaneous and controlled production of metal nanoparticles. This process does not require any thermal treatment and, hence, it is also attractive for material sciences such as heterogeneous catalysis. In this paper, silver-nanoparticle-based catalysts are prepared by transferring onion-grown silver nanoparticles onto inorganic supports. The resulting materials are active in the total oxidation of benzene, attesting that this novel bio-inspired concept is promising in inorganic catalysis. PMID:18844300

  6. Tissue-Engineered Fibrin-Based Heart Valve with Bio-Inspired Textile Reinforcement.

    PubMed

    Moreira, Ricardo; Neusser, Christine; Kruse, Magnus; Mulderrig, Shane; Wolf, Frederic; Spillner, Jan; Schmitz-Rode, Thomas; Jockenhoevel, Stefan; Mela, Petra

    2016-08-01

    The mechanical properties of tissue-engineered heart valves still need to be improved to enable their implantation in the systemic circulation. The aim of this study is to develop a tissue-engineered valve for the aortic position - the BioTexValve - by exploiting a bio-inspired composite textile scaffold to confer native-like mechanical strength and anisotropy to the leaflets. This is achieved by multifilament fibers arranged similarly to the collagen bundles in the native aortic leaflet, fixed by a thin electrospun layer directly deposited on the pattern. The textile-based leaflets are positioned into a 3D mould where the components to form a fibrin gel containing human vascular smooth muscle cells are introduced. Upon fibrin polymerization, a complete valve is obtained. After 21 d of maturation by static and dynamic stimulation in a custom-made bioreactor, the valve shows excellent functionality under aortic pressure and flow conditions, as demonstrated by hydrodynamic tests performed according to ISO standards in a mock circulation system. The leaflets possess remarkable burst strength (1086 mmHg) while remaining pliable; pronounced extracellular matrix production is revealed by immunohistochemistry and biochemical assay. This study demonstrates the potential of bio-inspired textile-reinforcement for the fabrication of functional tissue-engineered heart valves for the aortic position. PMID:27377438

  7. A Fluid-solid Numerical Model for the Analysis of Bio-inspired UUV

    NASA Astrophysics Data System (ADS)

    Mitra, Santanu; Krishnamurthy, Nagendra; Tafti, Danesh; Priya, Shashank

    2012-11-01

    This research will describe how a biology-inspired approach to engineering has placed jellyfish at the center of efforts to build next-generation underwater vehicles. In order to swim, jellyfish contract the circular muscles that line the undersurface of their bell. The motion of the bell from the relaxed position to the fully contracted position results in the mesoglea interacting with the surrounding water in such a way that causes the jellyfish to move forward. The present method uses two-dimensional fluid elements and plain strain hyperelastic structural elements for the numerical simulation of the problem. The equations of motion of the fluid are expressed as full N-S equation. A new type of bio-inspired boundary condition has been proposed. A prototype of the jellyfish setup has been developed for the experimental validation of the simulation results. The solution of the coupled system is accomplished by solving the two systems separately with the interaction effects using immersed boundary method. This study will be useful in accurate calculation of pressure distribution, maximum blocking stress, strain rate and actuator system for submerged autonomous vehicle. This study will also help in designing efficient propulsion and thruster mechanism for unmanned underwater vehicle. It is believed that the research presented in this paper advances the understanding of the dynamic behavior of bio-inspired UUV.

  8. Final Report for Bio-Inspired Approaches to Moving-Target Defense Strategies

    SciTech Connect

    Fink, Glenn A.; Oehmen, Christopher S.

    2012-09-01

    This report records the work and contributions of the NITRD-funded Bio-Inspired Approaches to Moving-Target Defense Strategies project performed by Pacific Northwest National Laboratory under the technical guidance of the National Security Agency’s R6 division. The project has incorporated a number of bio-inspired cyber defensive technologies within an elastic framework provided by the Digital Ants. This project has created the first scalable, real-world prototype of the Digital Ants Framework (DAF)[11] and integrated five technologies into this flexible, decentralized framework: (1) Ant-Based Cyber Defense (ABCD), (2) Behavioral Indicators, (3) Bioinformatic Clas- sification, (4) Moving-Target Reconfiguration, and (5) Ambient Collaboration. The DAF can be used operationally to decentralize many such data intensive applications that normally rely on collection of large amounts of data in a central repository. In this work, we have shown how these component applications may be decentralized and may perform analysis at the edge. Operationally, this will enable analytics to scale far beyond current limitations while not suffering from the bandwidth or computational limitations of centralized analysis. This effort has advanced the R6 Cyber Security research program to secure digital infrastructures by developing a dynamic means to adaptively defend complex cyber systems. We hope that this work will benefit both our client’s efforts in system behavior modeling and cyber security to the overall benefit of the nation.

  9. An experimental study of a bio-inspired corrugated airfoil for micro air vehicle applications

    NASA Astrophysics Data System (ADS)

    Murphy, Jeffery T.; Hu, Hui

    2010-08-01

    An experimental study was conducted to investigate the aerodynamic characteristics of a bio-inspired corrugated airfoil compared with a smooth-surfaced airfoil and a flat plate at the chord Reynolds number of Re C = 58,000-125,000 to explore the potential applications of such bio-inspired corrugated airfoils for micro air vehicle designs. In addition to measuring the aerodynamic lift and drag forces acting on the tested airfoils, a digital particle image velocimetry system was used to conduct detailed flowfield measurements to quantify the transient behavior of vortex and turbulent flow structures around the airfoils. The measurement result revealed clearly that the corrugated airfoil has better performance over the smooth-surfaced airfoil and the flat plate in providing higher lift and preventing large-scale flow separation and airfoil stall at low Reynolds numbers (Re C < 100,000). While aerodynamic performance of the smooth-surfaced airfoil and the flat plate would vary considerably with the changing of the chord Reynolds numbers, the aerodynamic performance of the corrugated airfoil was found to be almost insensitive to the Reynolds numbers. The detailed flow field measurements were correlated with the aerodynamic force measurement data to elucidate underlying physics to improve our understanding about how and why the corrugation feature found in dragonfly wings holds aerodynamic advantages for low Reynolds number flight applications.

  10. A new approach to tackle noise issue in miniature directional microphones: bio-inspired mechanical coupling

    NASA Astrophysics Data System (ADS)

    Liu, Haijun; Yu, Miao

    2010-04-01

    When using microphone array for sound source localization, the most fundamental step is to estimate the time difference of arrival (TDOA) between different microphones. Since TDOA is proportional to the microphone separation, the localization performance degrades with decreasing size relative to the sound wavelength. To address the size constraint of conventional directional microphones, a new approach is sought by utilizing the mechanical coupling mechanism found in the superacute ears of the parasitic fly Ormia ochracea. Previously, we have presented a novel bio-inspired directional microphone consisting of two circular clamped membranes structurally coupled by a center pivoted bridge, and demonstrated both theoretically and experimentally that the fly ear mechanism is replicable in a man-made structure. The emphasis of this article is on theoretical analysis of the thermal noise floor of the bio-inspired directional microphones. Using an equivalent two degrees-of-freedom model, the mechanical-thermal noise limit of the structurally coupled microphone is estimated and compared with those obtained for a single omni-directional microphone and a conventional microphone pair. Parametric studies are also conducted to investigate the effects of key normalized parameters on the noise floor and the signal-to-noise ratio (SNR).

  11. Gas barrier properties of bio-inspired Laponite-LC polymer hybrid films.

    PubMed

    Tritschler, Ulrich; Zlotnikov, Igor; Fratzl, Peter; Schlaad, Helmut; Grüner, Simon; Cölfen, Helmut

    2016-01-01

    Bio-inspired Laponite (clay)-liquid crystal (LC) polymer composite materials with high clay fractions (>80%) and a high level of orientation of the clay platelets, i.e. with structural features similar to the ones found in natural nacre, have been shown to exhibit a promising behavior in the context of reduced oxygen transmission. Key characteristics of these bio-inspired composite materials are their high inorganic content, high level of exfoliation and orientation of the clay platelets, and the use of a LC polymer forming the organic matrix in between the Laponite particles. Each single feature may be beneficial to increase the materials gas barrier property rendering this composite a promising system with advantageous barrier capacities. In this detailed study, Laponite/LC polymer composite coatings with different clay loadings were investigated regarding their oxygen transmission rate. The obtained gas barrier performance was linked to the quality, respective Laponite content and the underlying composite micro- and nanostructure of the coatings. Most efficient oxygen barrier properties were observed for composite coatings with 83% Laponite loading that exhibit a structure similar to sheet-like nacre. Further on, advantageous mechanical properties of these Laponite/LC polymer composites reported previously give rise to a multifunctional composite system. PMID:27225326

  12. Bio-inspired scale-like surface textures and their tribological properties.

    PubMed

    Greiner, Christian; Schäfer, Michael

    2015-08-01

    Friction, wear and the associated energy dissipation are major challenges in all systems containing moving parts. Examples range from nanoelectromechanical systems over hip prosthesis to off-shore wind turbines. Bionic approaches have proven to be very successful in many engineering problems, while investigating the potential of a bio-inspired approach in creating morphological surface textures is a relatively new field of research. Here, we developed laser-created textures inspired by the scales found on the skin of snakes and certain lizards. We show that this bio-inspired surface morphology reduced dry sliding friction forces by more than 40%. In lubricated contacts the same morphology increased friction by a factor of three. Two different kinds of morphologies, one with completely overlapping scales and one with the scales arranged in individual rows, were chosen. In lubricated as well as unlubricated contacts, the surface texture with the scales in rows showed lower friction forces than the completely overlapping ones. We anticipate that these results could have significant impact in all dry sliding contacts, ranging from nanoelectromechanical and micro-positioning systems up to large-scale tribological contacts which cannot be lubricated, e.g. because they are employed in a vacuum environment. PMID:26125522

  13. Study on the deformation of endothelial cells using a bio-inspired in vitro disease model.

    PubMed

    Seo, Eunseok; Seo, Kyung Won; Park, Ji-Won; Lee, Tae Geol; Lee, Sang Joon

    2015-03-01

    A bio-inspired in vitro disease model was developed to investigate the basic biophysics of atherosclerotic diseases. In vivo study was conducted in advance using zebrafish fed with a normal diet and a cholesterol-enriched diet. The endothelial cells (ECs) of the zebrafishes fed with a normal diet are tightly attached and aligned. Their collagen has a fiber-like structure. By contrast, the endothelial cells of the zebrafish on high cholesterol diet are disorganized and their collagen has broken structures. In vitro models of human umbilical vein endothelial cells (HUVECs) were established on collagen films to mimic such in vivo experimental results. The normal collagen film simulates the extracellular matrix (ECM) in the blood vessels of a normal zebrafish, and the collagenase-treated collagen film mimics the ECM in blood vessels of an abnormal zebrafish. The HUVECs cultured on the normal collagen film are tightly attached, similar to those of a normal zebrafish. However, the cells cultured on the collagenase-treated collagen film are aggregated and biomarkers of endothelial dysfunction are expressed on the surface of the abnormal endothelial cells established on the denatured collagen film. The present in vitro model using a bio-inspired collagen film has a great potential for the design of novel therapies for clinical treatments of atherosclerosis through better understanding on the outbreak mechanism of atherosclerosis. PMID:24534068

  14. A novel angle computation and calibration algorithm of bio-inspired sky-light polarization navigation sensor.

    PubMed

    Xian, Zhiwen; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Cao, Juliang; Wang, Yujie; Ma, Tao

    2014-01-01

    Navigation plays a vital role in our daily life. As traditional and commonly used navigation technologies, Inertial Navigation System (INS) and Global Navigation Satellite System (GNSS) can provide accurate location information, but suffer from the accumulative error of inertial sensors and cannot be used in a satellite denied environment. The remarkable navigation ability of animals shows that the pattern of the polarization sky can be used for navigation. A bio-inspired POLarization Navigation Sensor (POLNS) is constructed to detect the polarization of skylight. Contrary to the previous approach, we utilize all the outputs of POLNS to compute input polarization angle, based on Least Squares, which provides optimal angle estimation. In addition, a new sensor calibration algorithm is presented, in which the installation angle errors and sensor biases are taken into consideration. Derivation and implementation of our calibration algorithm are discussed in detail. To evaluate the performance of our algorithms, simulation and real data test are done to compare our algorithms with several exiting algorithms. Comparison results indicate that our algorithms are superior to the others and are more feasible and effective in practice. PMID:25225872

  15. A Novel Angle Computation and Calibration Algorithm of Bio-Inspired Sky-Light Polarization Navigation Sensor

    PubMed Central

    Xian, Zhiwen; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Cao, Juliang; Wang, Yujie; Ma, Tao

    2014-01-01

    Navigation plays a vital role in our daily life. As traditional and commonly used navigation technologies, Inertial Navigation System (INS) and Global Navigation Satellite System (GNSS) can provide accurate location information, but suffer from the accumulative error of inertial sensors and cannot be used in a satellite denied environment. The remarkable navigation ability of animals shows that the pattern of the polarization sky can be used for navigation. A bio-inspired POLarization Navigation Sensor (POLNS) is constructed to detect the polarization of skylight. Contrary to the previous approach, we utilize all the outputs of POLNS to compute input polarization angle, based on Least Squares, which provides optimal angle estimation. In addition, a new sensor calibration algorithm is presented, in which the installation angle errors and sensor biases are taken into consideration. Derivation and implementation of our calibration algorithm are discussed in detail. To evaluate the performance of our algorithms, simulation and real data test are done to compare our algorithms with several exiting algorithms. Comparison results indicate that our algorithms are superior to the others and are more feasible and effective in practice. PMID:25225872

  16. Boronic Acid: A Bio-Inspired Strategy To Increase the Sensitivity and Selectivity of Fluorescent NADH Probe.

    PubMed

    Wang, Lu; Zhang, Jingye; Kim, Beomsue; Peng, Juanjuan; Berry, Stuart N; Ni, Yong; Su, Dongdong; Lee, Jungyeol; Yuan, Lin; Chang, Young-Tae

    2016-08-24

    Fluorescent probes have emerged as an essential tool in the molecular recognition events in biological systems; however, due to the complex structures of certain biomolecules, it remains a challenge to design small-molecule fluorescent probes with high sensitivity and selectivity. Inspired by the enzyme-catalyzed reaction between biomolecule and probe, we present a novel combination-reaction two-step sensing strategy to improve sensitivity and selectivity. Based on this strategy, we successfully prepared a turn-on fluorescent reduced nicotinamide adenine dinucleotide (NADH) probe, in which boronic acid was introduced to bind with NADH and subsequently accelerate the sensing process. This probe shows remarkably improved sensitivity (detection limit: 0.084 μM) and selectivity to NADH in the absence of any enzymes. In order to improve the practicality, the boronic acid was further modified to change the measurement conditions from alkalescent (pH 9.5) to physiological environment (pH 7.4). Utilizing these probes, we not only accurately quantified the NADH weight in a health care product but also evaluated intracellular NADH levels in live cell imaging. Thus, these bio-inspired fluorescent probes offer excellent tools for elucidating the roles of NADH in biological systems as well as a practical strategy to develop future sensitive and selective probes for complicated biomolecules. PMID:27500425

  17. A Bio-Inspired Memory Model Embedded with a Causality Reasoning Function for Structural Fault Location

    PubMed Central

    Zheng, Wei; Wu, Chunxian

    2015-01-01

    Structural health monitoring (SHM) is challenged by massive data storage pressure and structural fault location. In response to these issues, a bio-inspired memory model that is embedded with a causality reasoning function is proposed for fault location. First, the SHM data for processing are divided into three temporal memory areas to control data volume reasonably. Second, the inherent potential of the causal relationships in structural state monitoring is mined. Causality and dependence indices are also proposed to establish the mechanism of quantitative description of the reason and result events. Third, a mechanism of causality reasoning is developed for the reason and result events to locate faults in a SHM system. Finally, a deformation experiment conducted on a steel spring plate demonstrates that the proposed model can be applied to real-time acquisition, compact data storage, and system fault location in a SHM system. Moreover, the model is compared with some typical methods based on an experimental benchmark dataset. PMID:25798991

  18. Hydrogels from Amorphous Calcium Carbonate and Polyacrylic Acid: Bio-Inspired Materials for "Mineral Plastics".

    PubMed

    Sun, Shengtong; Mao, Li-Bo; Lei, Zhouyue; Yu, Shu-Hong; Cölfen, Helmut

    2016-09-19

    Given increasing environmental issues due to the large usage of non-biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are in high demand. One feasible strategy is the bio-inspired synthesis of mineral-based hybrid materials. Herein we report a facile route for an amorphous CaCO3 (ACC)-based hydrogel consisting of very small ACC nanoparticles physically cross-linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self-healable. Upon drying, the hydrogel forms free-standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the "mineral plastics". PMID:27444970

  19. A Bio-Inspired Approach for the Reduction of Left Ventricular Workload

    PubMed Central

    Pahlevan, Niema M.; Gharib, Morteza

    2014-01-01

    Previous studies have demonstrated the existence of optimization criteria in the design and development of mammalians cardiovascular systems. Similarities in mammalian arterial wave reflection suggest there are certain design criteria for the optimization of arterial wave dynamics. Inspired by these natural optimization criteria, we investigated the feasibility of optimizing the aortic waves by modifying wave reflection sites. A hydraulic model that has physical and dynamical properties similar to a human aorta and left ventricle was used for a series of in-vitro experiments. The results indicate that placing an artificial reflection site (a ring) at a specific location along the aorta may create a constructive wave dynamic that could reduce LV pulsatile workload. This simple bio-inspired approach may have important implications for the future of treatment strategies for diseased aorta. PMID:24475239

  20. Distributed Synchronization Technique for OFDMA-Based Wireless Mesh Networks Using a Bio-Inspired Algorithm

    PubMed Central

    Kim, Mi Jeong; Maeng, Sung Joon; Cho, Yong Soo

    2015-01-01

    In this paper, a distributed synchronization technique based on a bio-inspired algorithm is proposed for an orthogonal frequency division multiple access (OFDMA)-based wireless mesh network (WMN) with a time difference of arrival. The proposed time- and frequency-synchronization technique uses only the signals received from the neighbor nodes, by considering the effect of the propagation delay between the nodes. It achieves a fast synchronization with a relatively low computational complexity because it is operated in a distributed manner, not requiring any feedback channel for the compensation of the propagation delays. In addition, a self-organization scheme that can be effectively used to construct 1-hop neighbor nodes is proposed for an OFDMA-based WMN with a large number of nodes. The performance of the proposed technique is evaluated with regard to the convergence property and synchronization success probability using a computer simulation. PMID:26225974

  1. A Bio-Inspired Method for the Constrained Shortest Path Problem

    PubMed Central

    Wang, Hongping; Lu, Xi; Wang, Qing

    2014-01-01

    The constrained shortest path (CSP) problem has been widely used in transportation optimization, crew scheduling, network routing and so on. It is an open issue since it is a NP-hard problem. In this paper, we propose an innovative method which is based on the internal mechanism of the adaptive amoeba algorithm. The proposed method is divided into two parts. In the first part, we employ the original amoeba algorithm to solve the shortest path problem in directed networks. In the second part, we combine the Physarum algorithm with a bio-inspired rule to deal with the CSP. Finally, by comparing the results with other method using an examples in DCLC problem, we demonstrate the accuracy of the proposed method. PMID:24959603

  2. Segmentation algorithm via Cellular Neural/Nonlinear Network: implementation on Bio-inspired hardware platform

    NASA Astrophysics Data System (ADS)

    Karabiber, Fethullah; Vecchio, Pietro; Grassi, Giuseppe

    2011-12-01

    The Bio-inspired (Bi-i) Cellular Vision System is a computing platform consisting of sensing, array sensing-processing, and digital signal processing. The platform is based on the Cellular Neural/Nonlinear Network (CNN) paradigm. This article presents the implementation of a novel CNN-based segmentation algorithm onto the Bi-i system. Each part of the algorithm, along with the corresponding implementation on the hardware platform, is carefully described through the article. The experimental results, carried out for Foreman and Car-phone video sequences, highlight the feasibility of the approach, which provides a frame rate of about 26 frames/s. Comparisons with existing CNN-based methods show that the conceived approach is more accurate, thus representing a good trade-off between real-time requirements and accuracy.

  3. A bio-inspired system for spatio-temporal recognition in static and video imagery

    NASA Astrophysics Data System (ADS)

    Khosla, Deepak; Moore, Christopher K.; Chelian, Suhas

    2007-04-01

    This paper presents a bio-inspired method for spatio-temporal recognition in static and video imagery. It builds upon and extends our previous work on a bio-inspired Visual Attention and object Recognition System (VARS). The VARS approach locates and recognizes objects in a single frame. This work presents two extensions of VARS. The first extension is a Scene Recognition Engine (SCE) that learns to recognize spatial relationships between objects that compose a particular scene category in static imagery. This could be used for recognizing the category of a scene, e.g., office vs. kitchen scene. The second extension is the Event Recognition Engine (ERE) that recognizes spatio-temporal sequences or events in sequences. This extension uses a working memory model to recognize events and behaviors in video imagery by maintaining and recognizing ordered spatio-temporal sequences. The working memory model is based on an ARTSTORE1 neural network that combines an ART-based neural network with a cascade of sustained temporal order recurrent (STORE)1 neural networks. A series of Default ARTMAP classifiers ascribes event labels to these sequences. Our preliminary studies have shown that this extension is robust to variations in an object's motion profile. We evaluated the performance of the SCE and ERE on real datasets. The SCE module was tested on a visual scene classification task using the LabelMe2 dataset. The ERE was tested on real world video footage of vehicles and pedestrians in a street scene. Our system is able to recognize the events in this footage involving vehicles and pedestrians.

  4. A three dimensional unsteady iterative panel method with vortex particle wakes and boundary layer model for bio-inspired multi-body wings

    NASA Astrophysics Data System (ADS)

    Dhruv, Akash; Blower, Christopher; Wickenheiser, Adam M.

    2015-03-01

    The ability of UAVs to operate in complex and hostile environments makes them useful in military and civil operations concerning surveillance and reconnaissance. However, limitations in size of UAVs and communication delays prohibit their operation close to the ground and in cluttered environments, which increase risks associated with turbulence and wind gusts that cause trajectory deviations and potential loss of the vehicle. In the last decade, scientists and engineers have turned towards bio-inspiration to solve these issues by developing innovative flow control methods that offer better stability, controllability, and maneuverability. This paper presents an aerodynamic load solver for bio-inspired wings that consist of an array of feather-like flaps installed across the upper and lower surfaces in both the chord- and span-wise directions, mimicking the feathers of an avian wing. Each flap has the ability to rotate into both the wing body and the inbound airflow, generating complex flap configurations unobtainable by traditional wings that offer improved aerodynamic stability against gusting flows and turbulence. The solver discussed is an unsteady three-dimensional iterative doublet panel method with vortex particle wakes. This panel method models the wake-body interactions between multiple flaps effectively without the need to define specific wake geometries, thereby eliminating the need to manually model the wake for each configuration. To incorporate viscous flow characteristics, an iterative boundary layer theory is employed, modeling laminar, transitional and turbulent regions over the wing's surfaces, in addition to flow separation and reattachment locations. This technique enables the boundary layer to influence the wake strength and geometry both within the wing and aft of the trailing edge. The results obtained from this solver are validated using experimental data from a low-speed suction wind tunnel operating at Reynolds Number 300,000. This method

  5. A bio-inspired two-layer sensing structure of polypeptide and multiple-walled carbon nanotube to sense small molecular gases.

    PubMed

    Wang, Li-Chun; Su, Tseng-Hsiung; Ho, Cheng-Long; Yang, Shang-Ren; Chiu, Shih-Wen; Kuo, Han-Wen; Tang, Kea-Tiong

    2015-01-01

    In this paper, we propose a bio-inspired, two-layer, multiple-walled carbon nanotube (MWCNT)-polypeptide composite sensing device. The MWCNT serves as a responsive and conductive layer, and the nonselective polypeptide (40 mer) coating the top of the MWCNT acts as a filter into which small molecular gases pass. Instead of using selective peptides to sense specific odorants, we propose using nonselective, peptide-based sensors to monitor various types of volatile organic compounds. In this study, depending on gas interaction and molecular sizes, the randomly selected polypeptide enabled the recognition of certain polar volatile chemical vapors, such as amines, and the improved discernment of low-concentration gases. The results of our investigation demonstrated that the polypeptide-coated sensors can detect ammonia at a level of several hundred ppm and barely responded to triethylamine. PMID:25751078

  6. A Bio-Inspired Two-Layer Sensing Structure of Polypeptide and Multiple-Walled Carbon Nanotube to Sense Small Molecular Gases

    PubMed Central

    Wang, Li-Chun; Su, Tseng-Hsiung; Ho, Cheng-Long; Yang, Shang-Ren; Chiu, Shih-Wen; Kuo, Han-Wen; Tang, Kea-Tiong

    2015-01-01

    In this paper, we propose a bio-inspired, two-layer, multiple-walled carbon nanotube (MWCNT)-polypeptide composite sensing device. The MWCNT serves as a responsive and conductive layer, and the nonselective polypeptide (40 mer) coating the top of the MWCNT acts as a filter into which small molecular gases pass. Instead of using selective peptides to sense specific odorants, we propose using nonselective, peptide-based sensors to monitor various types of volatile organic compounds. In this study, depending on gas interaction and molecular sizes, the randomly selected polypeptide enabled the recognition of certain polar volatile chemical vapors, such as amines, and the improved discernment of low-concentration gases. The results of our investigation demonstrated that the polypeptide-coated sensors can detect ammonia at a level of several hundred ppm and barely responded to triethylamine. PMID:25751078

  7. Combined bio-inspired/evolutionary computational methods in cross-layer protocol optimization for wireless ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2011-06-01

    Published studies have focused on the application of one bio-inspired or evolutionary computational method to the functions of a single protocol layer in a wireless ad hoc sensor network (WSN). For example, swarm intelligence in the form of ant colony optimization (ACO), has been repeatedly considered for the routing of data/information among nodes, a network-layer function, while genetic algorithms (GAs) have been used to select transmission frequencies and power levels, physical-layer functions. Similarly, artificial immune systems (AISs) as well as trust models of quantized data reputation have been invoked for detection of network intrusions that cause anomalies in data and information; these act on the application and presentation layers. Most recently, a self-organizing scheduling scheme inspired by frog-calling behavior for reliable data transmission in wireless sensor networks, termed anti-phase synchronization, has been applied to realize collision-free transmissions between neighboring nodes, a function of the MAC layer. In a novel departure from previous work, the cross-layer approach to WSN protocol design suggests applying more than one evolutionary computational method to the functions of the appropriate layers to improve the QoS performance of the cross-layer design beyond that of one method applied to a single layer's functions. A baseline WSN protocol design, embedding GAs, anti-phase synchronization, ACO, and a trust model based on quantized data reputation at the physical, MAC, network, and application layers, respectively, is constructed. Simulation results demonstrate the synergies among the bioinspired/ evolutionary methods of the proposed baseline design improve the overall QoS performance of networks over that of a single computational method.

  8. Bio-Inspired Molecular Catalysts for Hydrogen Oxidation and Hydrogen Production

    SciTech Connect

    Ho, Ming-Hsun; Chen, Shentan; Rousseau, Roger J.; Dupuis, Michel; Bullock, R. Morris; Raugei, Simone

    2013-06-03

    Recent advances in Ni-based bio-inspired catalysts obtained in the Center for Molecular Electrocatalysis, an Energy Frontier Research Center (EFRC) at the Pacific Northwest National Laboratory, demonstrated the possibility of cleaving H2 or generating H2 heterolytically with turnover frequencies comparable or superior to those of hydrogenase enzymes. In these catalysts the transformation between H2 and protons proceeds via an interplay between proton, hydride and electron transfer steps and involves the interaction of a dihydrogen molecule with both a Ni(II) center and with pendant amine bases incorporated in a six-membered ring, which act as proton relays. These catalytic platforms are well designed in that when protons are correctly positioned (endo) toward the Raugei-ACS-Books.docxPrinted 12/18/12 2 metal center, catalysis proceeds at very high rates. We will show that the proton removal (for H2 oxidation) and proton delivery (for H2 production) are often the rate determining steps. Furthermore, the presence of multiple protonation sites gives rise to reaction intermediates with protons not correctly positioned (exo relative to the metal center). These isomers are easily accessible kinetically and are detrimental to catalysis because of the slow isomerization processes necessary to convert them to the catalytically competent endo isomers. In this chapter we will review the major findings of our computational investigation on the role of proton relays for H2 chemistry and provide guidelines for the design of new catalysts. This research was carried out in the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle. Computational resources were provided at W. R. Wiley Environmental Molecular Science Laboratory (EMSL), a Raugei-Bio-Inspired Molecular-Catalysts-for-Hydrogen- Oxidation

  9. Surgical robotics: A look-back of latest advancement and bio-inspired ways to tackle existing challenges

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Liu, Jing

    2012-12-01

    This article is dedicated to present a review on existing challenges and latest developments in surgical robotics in attempts to overcome the obstacles lying behind. Rather than to perform an exhaustive evaluation, we would emphasize more on the new insight by digesting the emerging bio-inspired surgical technologies with potentials to revolutionize the field. Typical approaches, possible applications, advantages and technical challenges were discussed. Evolutions of surgical robotics and future trends were analyzed. It can be found that, the major difficulties in the field of surgical robots may not be properly addressed by only using conventional approaches. As an alternative, bio-inspired methods or materials may shed light on new innovations. While endeavors to deal with existing strategies still need to be made, attentions should be paid to also borrow ideas from nature.

  10. Converging the capabilities of EAP artificial muscles and the requirements of bio-inspired robotics

    NASA Astrophysics Data System (ADS)

    Hanson, David F.; White, Victor

    2004-07-01

    The characteristics of Electro-actuated polymers (EAP) are typically considered inadequate for applications in robotics. But in recent years, there has been both dramatic increases in EAP technological capbilities and reductions in power requirements for actuating bio-inspired robotics. As the two trends continue to converge, one may anticipate that dramatic breakthroughs in biologically inspired robotic actuation will result due to the marraige of these technologies. This talk will provide a snapshot of how EAP actuator scientists and roboticists may work together on a common platform to accelerate the growth of both technologies. To demonstrate this concept of a platform to accelerate this convergence, the authors will discuss their work in the niche application of robotic facial expression. In particular, expressive robots appear to be within the range of EAP actuation, thanks to their low force requirements. Several robots will be shown that demonstrate realistic expressions with dramatically decreased force requirements. Also, detailed descriptions will be given of the engineering innovations that have enabled these robotics advancements-most notably, Structured-Porosity Elastomer Materials (SPEMs). SPEM manufacturing techniques create delicate cell-structures in a variety of elastomers that maintain the high elongation characteristics of the mother material, but because of the porisity, behave as sponge-materials, thus lower the force required to emulate facial expressions to levels output by several extant EAP actuators.

  11. Bio-inspired co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Hou, Yidong; Abrams, Billie L.; Vesborg, Peter C. K.; Bjørketun, Mårten E.; Herbst, Konrad; Bech, Lone; Seger, Brian; Pedersen, Thomas; Hansen, Ole; Rossmeisl, Jan; Dahl, Søren; Nørskov, Jens K.; Chorkendorff, Ib

    2011-10-01

    The production of fuels directly or indirectly from sunlight represents one of the major challenges to the development of a sustainable energy system. Hydrogen is the simplest fuel to produce and while platinum and other noble metals are efficient catalysts for photoelectrochemical hydrogen evolution, earth-abundant alternatives are needed for largescale use. We show that bio-inspired molecular clusters based on molybdenum sulfides and tungsten sulfides mimic nature's enzymes for hydrogen evolution, molybdenum sulfides evolve hydrogen at a slightly higher overpotential than platinum when deposited on various supports. It will be demonstrated how this overpotential can be eliminated by depositing the same type of hydrogen evolution catalyst on p-type Si which can harvest the red part of the solar spectrum. Such a system could constitute the cathode part of a tandem dream device where the red part of the spectrum is utilized for hydrogen evolution while the blue part is reserved for the more difficult oxygen evolution. The samples have been illuminated with a simulated red part of the solar spectrum i.e. long wavelength (" > 620 nm) part of simulated AM 1.5G radiation. The current densities at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10%. The experimental observations are supported by DFT calculations of the Mo3S4 cluster adsorbed on the hydrogen-terminated silicon surface providing insights into the nature of the active site.

  12. Bio-inspired hard-to-soft interface for implant integration to bone

    PubMed Central

    Zhou, Yan; Snead, Malcolm L.; Tamerler, Candan

    2014-01-01

    Accomplishing full, functional integration at the host-to-biomaterial interface has been a critical roadblock in engineering implants with performance similar to biological materials. Molecular recognition-based self-assembly, coupled with biochemical signaling, may lead to controllable and predictable cellular differentiation at the implant interface. Here, we engineer a bio-inspired interface built upon a chimeric peptide. Binding to the biomaterial interface is achieved using a molecular recognition domain specific for the titanium/titanium alloy implant surface and a biochemical signal guiding stem cells to differentiate by activating the Wnt signaling pathway for bone formation. During a critical period of host cell growth and determination, the bioactive implant interface signals mouse, as well as human, stem cells to differentiate along osteogenic lineages. The Wnt-induced cells show enhanced mineral deposition in an extracellular matrix of their creation and an enhanced gene expression profile consistent with osteogenesis, thereby providing a bone-to-implant interface that promotes bone regeneration. PMID:25461292

  13. A compact bio-inspired visible/NIR imager for image-guided surgery (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Gao, Shengkui; Garcia, Missael; Edmiston, Chris; York, Timothy; Marinov, Radoslav; Mondal, Suman B.; Zhu, Nan; Sudlow, Gail P.; Akers, Walter J.; Margenthaler, Julie A.; Liang, Rongguang; Pepino, Marta; Achilefu, Samuel; Gruev, Viktor

    2016-03-01

    Inspired by the visual system of the morpho butterfly, we have designed, fabricated, tested and clinically translated an ultra-sensitive, light weight and compact imaging sensor capable of simultaneously capturing near infrared (NIR) and visible spectrum information. The visual system of the morpho butterfly combines photosensitive cells with spectral filters at the receptor level. The spectral filters are realized by alternating layers of high and low dielectric constant, such as air and cytoplasm. We have successfully mimicked this concept by integrating pixelated spectral filters, realized by alternating silicon dioxide and silicon nitrate layers, with an array of CCD detectors. There are four different types of pixelated spectral filters in the imaging plane: red, green, blue and NIR. The high optical density (OD) of all spectral filters (OD>4) allow for efficient rejections of photons from unwanted bands. The single imaging chip weighs 20 grams with form factor of 5mm by 5mm. The imaging camera is integrated with a goggle display system. A tumor targeted agent, LS301, is used to identify all spontaneous tumors in a transgenic PyMT murine model of breast cancer. The imaging system achieved sensitivity of 98% and selectivity of 95%. We also used our imaging sensor to locate sentinel lymph nodes (SLNs) in patients with breast cancer using indocyanine green tracer. The surgeon was able to identify 100% of SLNs when using our bio-inspired imaging system, compared to 93% when using information from the lymphotropic dye and 96% when using information from the radioactive tracer.

  14. Synthesis of bio-inspired multilayer polarizers and their application to anti-counterfeiting.

    PubMed

    Poncelet, O; Tallier, G; Simonis, P; Cornet, A; Francis, L A

    2015-04-01

    Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization effects on light such as color contrast or geometrical polarization rotation by reflection on their wing scales. The photonic structures found on these species that show these properties are multilayered spherical cavities or triangular grooves which polarize the light due to multiple inner reflections. These polarization effects, in addition to the intrinsic color-mixing properties of these photonic structures, are of interest in the anti-counterfeiting field due to their invisibility to the naked eye. In this paper, we report micro-fabrication techniques to produce bio-inspired cylindrical grooves (C-grooves) and triangular grooves (V-grooves) that demonstrate the same properties. Theoretical analyses were carried out by using multi-scale simulation (MS) as well as by finite-difference time-domain (FDTD) in order to compare the polarization capability of both structures. The V-grooves show greater polarization contrast than the C-grooves, but the spectrum is specular. The C-grooves exhibit lower polarization effects but have a dispersive spectrum. In both cases, the structures show additional optical properties, such as diffraction, macroscopic color contrast under a polarizer, and contrast inversion due to geometries which contribute to their uniqueness. PMID:25717055

  15. Light Manipulation for Organic Optoelectronics Using Bio-inspired Moth's Eye Nanostructures

    NASA Astrophysics Data System (ADS)

    Zhou, Lei; Ou, Qing-Dong; Chen, Jing-De; Shen, Su; Tang, Jian-Xin; Li, Yan-Qing; Lee, Shuit-Tong

    2014-02-01

    Organic-based optoelectronic devices, including light-emitting diodes (OLEDs) and solar cells (OSCs) hold great promise as low-cost and large-area electro-optical devices and renewable energy sources. However, further improvement in efficiency remains a daunting challenge due to limited light extraction or absorption in conventional device architectures. Here we report a universal method of optical manipulation of light by integrating a dual-side bio-inspired moth's eye nanostructure with broadband anti-reflective and quasi-omnidirectional properties. Light out-coupling efficiency of OLEDs with stacked triple emission units is over 2 times that of a conventional device, resulting in drastic increase in external quantum efficiency and current efficiency to 119.7% and 366 cd A-1 without introducing spectral distortion and directionality. Similarly, the light in-coupling efficiency of OSCs is increased 20%, yielding an enhanced power conversion efficiency of 9.33%. We anticipate this method would offer a convenient and scalable way for inexpensive and high-efficiency organic optoelectronic designs.

  16. Pushing the lipid envelope: using bio-inspired nanocomposites to understand and exploit lipid membrane limitations

    NASA Astrophysics Data System (ADS)

    Montano, Gabriel

    Lipids serve as the organizing matrix material for biological membranes, the site of interaction of cells with the external environment. . As such, lipids play a critical role in structure/function relationships of an extraordinary number of critical biological processes. In this talk, we will look at bio-inspired membrane assemblies to better understand the roles of lipids in biological systems as well as attempt to generate materials that can mimic and potentially advance upon biological membrane processes. First, we will investigate the response of lipids to adverse conditions. In particular, I will present data that demonstrates the response of lipids to harsh conditions and how such responses can be exploited to generate nanocomposite rearrangements. I will also show the effect of adding the endotoxin lipopolysaccharide (LPS) to lipid bilayer assemblies and describe implications on our understanding of LPS organization in biological systems as well as describe induced lipid modifications that can be exploited to organize membrane composites with precise, two-dimensional geometric control. Lastly, I will describe the use of amphiphilic block copolymers to create membrane nanocomposites capable of mimicking biological systems. In particular, I will describe the use of our polymer-based membranes in creating artificial photosynthetic assemblies that rival biological systems in function in a more flexible, dynamic matrix.

  17. Light Manipulation for Organic Optoelectronics Using Bio-inspired Moth's Eye Nanostructures

    PubMed Central

    Zhou, Lei; Ou, Qing-Dong; Chen, Jing-De; Shen, Su; Tang, Jian-Xin; Li, Yan-Qing; Lee, Shuit-Tong

    2014-01-01

    Organic-based optoelectronic devices, including light-emitting diodes (OLEDs) and solar cells (OSCs) hold great promise as low-cost and large-area electro-optical devices and renewable energy sources. However, further improvement in efficiency remains a daunting challenge due to limited light extraction or absorption in conventional device architectures. Here we report a universal method of optical manipulation of light by integrating a dual-side bio-inspired moth's eye nanostructure with broadband anti-reflective and quasi-omnidirectional properties. Light out-coupling efficiency of OLEDs with stacked triple emission units is over 2 times that of a conventional device, resulting in drastic increase in external quantum efficiency and current efficiency to 119.7% and 366 cd A−1 without introducing spectral distortion and directionality. Similarly, the light in-coupling efficiency of OSCs is increased 20%, yielding an enhanced power conversion efficiency of 9.33%. We anticipate this method would offer a convenient and scalable way for inexpensive and high-efficiency organic optoelectronic designs. PMID:24509524

  18. Photo-crosslinking, bio-inspired terpolymer adhesives intended for medical applications

    NASA Astrophysics Data System (ADS)

    Harper, Tristan

    A bio-inspired, modular terpolymer adhesive has been synthesized containing three different functionalities: a photocrosslinking segment, wet adhesion segment, and a water soluble segment. Wet adhesion is brought on by an amino acid from mussel byssal plaques called 3,4-dihydroxyphenyl--L-alanine, which has been known to generate strong bonding under wet conditions. The photocrosslinking segment consists of an anthracene based monomer used for mechanical fortification of polymer chains. The water soluble segment consists of poly(acrylic acid), which has been known to increase water solubility of polymers and increase adhesion strength of adhesives. The terpolymer was designed to easily applicable using biologically friendly solvents including water and ethanol. Structural design was confirmed by NMR and UV-Vis spectroscopy. Reversible cycloaddition reactions were executed using a handheld UV lamp along with a photoreactor. Molecular weight increases were seen from 4.120 x 104 Da to 7.429 x 104 Da. Lap shear strength testing showed effects of UV exposure through increases in adhesion energy above 450%. Multiple application variables were tested to determine optimal conditions, such as solvent, concentration, and substrate. Currently, optimal conditions show a 1:1 weight ratio of polymer:solvent in water for all surfaces.

  19. A wireless fatigue monitoring system utilizing a bio-inspired tree ring data tracking technique.

    PubMed

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-01-01

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc. PMID:24603635

  20. Bio-inspired direct patterning functional nanothin microlines: controllable liquid transfer.

    PubMed

    Wang, Qianbin; Meng, Qingan; Wang, Pengwei; Liu, Huan; Jiang, Lei

    2015-04-28

    Developing a general and low-cost strategy that enables direct patterning of microlines with nanometer thickness from versatile liquid-phase functional materials and precise positioning of them on various substrates remains a challenge. Herein, with inspiration from the oriental wisdom to control ink transfer by Chinese brushes, we developed a facile and general writing strategy to directly pattern various functional microlines with homogeneous distribution and nanometer-scale thickness. It is demonstrated that the width and thickness of the microlines could be well-controlled by tuning the writing method, providing guidance for the adaptation of this technique to various systems. It is also shown that various functional liquid-phase materials, such as quantum dots, small molecules, polymers, and suspensions of nanoparticles, could directly write on the substrates with intrinsic physicochemical properties well-preserved. Moreover, this technique enabled direct patterning of liquid-phase materials on certain microdomains, even in multiple layered style, thus a microdomain localized chemical reaction and the patterned surface chemical modification were enabled. This bio-inspired direct writing device will shed light on the template-free printing of various functional micropatterns, as well as the integrated functional microdevices. PMID:25845024

  1. Targeting the finite-deformation response of wavy biological tissues with bio-inspired material architectures.

    PubMed

    Tu, Wenqiong; Pindera, Marek-Jerzy

    2013-12-01

    The Particle Swarm Optimization algorithm driven by a homogenized-based model is employed to target the response of three types of heart-valve chordae tendineae with different stiffening characteristics due to different degrees of waviness of collagen fibril/fiber bundles. First, geometric and material parameters are identified through an extensive parametric study that produce excellent agreement of the simulated response based on simplified unit cell architectures with the actual response of the complex biological tissue. These include amplitude and wavelength of the crimped chordae microstructure, elastic moduli of the constituent phases, and degree of microstructural refinement of the stiff phase at fixed volume fraction whose role in the stiffening response is elucidated. The study also reveals potential non-uniqueness of bio-inspired wavy microstructures in attaining the targeted response of certain chordae tendineae crimp configurations. The homogenization-based Particle Swarm Optimization algorithm, whose predictions are validated through the parametric study, is then shown to be an excellent tool in identifying optimal unit cell architectures in the design space that exhibits very steep gradients. Finally, defect criticality of optimal unit cell architectures is investigated in order to assess their feasibility in replacing actual biological tendons with stiffening characteristics. PMID:24018396

  2. Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong Composites

    PubMed Central

    Han, Yue; Zhang, Xiaohua; Yu, Xueping; Zhao, Jingna; Li, Shan; Liu, Feng; Gao, Peng; Zhang, Yongyi; Zhao, Tong; Li, Qingwen

    2015-01-01

    High performance nanocomposites require well dispersion and high alignment of the nanometer-sized components, at a high mass or volume fraction as well. However, the road towards such composite structure is severely hindered due to the easy aggregation of these nanometer-sized components. Here we demonstrate a big step to approach the ideal composite structure for carbon nanotube (CNT) where all the CNTs were highly packed, aligned, and unaggregated, with the impregnated polymers acting as interfacial adhesions and mortars to build up the composite structure. The strategy was based on a bio-inspired aggregation control to limit the CNT aggregation to be sub 20–50 nm, a dimension determined by the CNT growth. After being stretched with full structural relaxation in a multi-step way, the CNT/polymer (bismaleimide) composite yielded super-high tensile strengths up to 6.27–6.94 GPa, more than 100% higher than those of carbon fiber/epoxy composites, and toughnesses up to 117–192 MPa. We anticipate that the present study can be generalized for developing multifunctional and smart nanocomposites where all the surfaces of nanometer-sized components can take part in shear transfer of mechanical, thermal, and electrical signals. PMID:26098627

  3. Bio-inspired catechol chemistry for electrophoretic nanotechnology of oxide films.

    PubMed

    Wang, Y; Zhitomirsky, I

    2012-08-15

    Bio-inspired chemical approach has been developed for the surface modification and electrophoretic deposition of manganese dioxide and zirconia nanoparticles, prepared by chemical precipitation methods. Caffeic acid, trans-cinnamic acid, p-coumaric acid, and 2,4-dihydroxycinnamic acid were investigated for the surface modification of the nanoparticles. The influence of the structure of the organic molecules on their adsorption on the oxide nanoparticles has been investigated. The mechanism of caffeic acid adsorption was similar to that of natural catecholic amino acid, L-3,4-dihydroxyphenylalanine. The use of caffeic acid allowed for agglomerate-free synthesis, efficient dispersion, charging, electrophoretic deposition and co-deposition of manganese dioxide and zirconia nanoparticles. The deposition yield data, coupled with the results of thermogravimetric analysis, X-ray diffraction analysis, and Fourier transform infrared spectroscopy, showed that surface chemistry, rather than the crystal structure, determined the adsorption behavior. Electron microscopy and energy dispersive spectroscopy investigations showed the formation of nanostructured oxide films and composites. The deposit composition can be varied. PMID:22652591

  4. A bio-inspired aquatic flow sensor using an artificial cell membrane

    NASA Astrophysics Data System (ADS)

    Pinto, Preston A.; Garrison, Kevin; Leo, Donald J.; Sarles, Stephen A.

    2012-04-01

    Receptors known as hair cells give many animals this ability to sense a wide range of stimuli, such as sound, orientation, vibration, and flow. Previous researchers have mimicked natural hair cells by building electromechanical sensor systems that produce an electric response due to the bending of artificial hairs. Inspired by the roles of sensory hairs in fish, this work builds on previous research by investigating the flow dependent electrical response of a 'skin'-encapsulated artificial hair cell in an aqueous flow. This study presents the design, fabrication, and characterization of a flow sensor that will help close the loop between the sensing mechanisms and control strategies that aquatic organisms employ for functions such as locomotion regulation, prey capture, and particulate capture. The system is fabricated with a durable, artificial bilayer that forms at the interface between lipid-encased aqueous volumes contained in a flexible encapsulated polyurethane substrate. Flow experiments are conducted by placing the bio-inspired sensor in a flow chamber and subjecting it to pulse-like flows. Specifically, through temporal responses of the measured current and power spectral density (PSD) analysis, our results show that the amplitude and frequency of the current response are related to the flow over the hair. This preliminary study demonstrates that the encapsulated artificial hair cell flow sensor is capable of sensing changes in flow through a mechanoelectrical response and that its sensing capabilities may be altered by varying its surface morphology.

  5. Hair flow sensors: from bio-inspiration to bio-mimicking—a review

    NASA Astrophysics Data System (ADS)

    Tao, Junliang; (Bill Yu, Xiong

    2012-11-01

    A great many living beings, such as aquatics and arthropods, are equipped with highly sensitive flow sensors to help them survive in challenging environments. These sensors are excellent sources of inspiration for developing application-driven artificial flow sensors with high sensitivity and performance. This paper reviews the bio-inspirations on flow sensing in nature and the bio-mimicking efforts to emulate such sensing mechanisms in recent years. The natural flow sensing systems in aquatics and arthropods are reviewed to highlight inspirations at multiple levels such as morphology, sensing mechanism and information processing. Biomimetic hair flow sensors based on different sensing mechanisms and fabrication technologies are also reviewed to capture the recent accomplishments and to point out areas where further progress is necessary. Biomimetic flow sensors are still in their early stages. Further efforts are required to unveil the sensing mechanisms in the natural biological systems and to achieve multi-level bio-mimicking of the natural system to develop their artificial counterparts.

  6. Harnessing Electrostatic Forces to Grow Bio-inspired Hierarchical Vascular Networks

    NASA Astrophysics Data System (ADS)

    Behler, Kristopher; Melrose, Zachary; Schott, Andrew; Wetzel, Eric

    2012-02-01

    Vascular networks provide a system for fluid distribution. Artificial vascular materials with enhanced properties are currently being developed that could ultimately be integrated into systems reliant upon fluid transport while retaining their structural properties. An uninterrupted and controllable supply of liquid is optimal for many applications such as continual self-healing materials, in-situ delivery of index matched fluids, thermal management and drug delivery systems could benefit from a bio-inspired vascular approach that combines complex network geometries with minimal processing parameters. Two such approaches to induce vascular networks are electrohydrodynamic viscous fingering (EHVF) and electrical treeing (ET). EHVF is a phenomenon that occurs when a low viscosity liquid is forced through a high viscosity fluid or matrix, resulting in branches due to capillary and viscous forces in the high viscosity material. By applying voltages of 0 -- 60 kV, finger diameter is reduced. ET is the result of partial discharges in a dielectric material. In the vicinity of a small diameter electrode, the local electric field is greater than the global dielectric strength, causing a localized, step-wise, breakdown to occur forming a highly branched interconnected structure. ET is a viable method to produce networks on a smaller, micron, scale than the products of the EHVF method.

  7. Soft network composite materials with deterministic and bio-inspired designs

    NASA Astrophysics Data System (ADS)

    Jang, Kyung-In; Chung, Ha Uk; Xu, Sheng; Lee, Chi Hwan; Luan, Haiwen; Jeong, Jaewoong; Cheng, Huanyu; Kim, Gwang-Tae; Han, Sang Youn; Lee, Jung Woo; Kim, Jeonghyun; Cho, Moongee; Miao, Fuxing; Yang, Yiyuan; Jung, Han Na; Flavin, Matthew; Liu, Howard; Kong, Gil Woo; Yu, Ki Jun; Rhee, Sang Il; Chung, Jeahoon; Kim, Byunggik; Kwak, Jean Won; Yun, Myoung Hee; Kim, Jin Young; Song, Young Min; Paik, Ungyu; Zhang, Yihui; Huang, Yonggang; Rogers, John A.

    2015-03-01

    Hard and soft structural composites found in biology provide inspiration for the design of advanced synthetic materials. Many examples of bio-inspired hard materials can be found in the literature; far less attention has been devoted to soft systems. Here we introduce deterministic routes to low-modulus thin film materials with stress/strain responses that can be tailored precisely to match the non-linear properties of biological tissues, with application opportunities that range from soft biomedical devices to constructs for tissue engineering. The approach combines a low-modulus matrix with an open, stretchable network as a structural reinforcement that can yield classes of composites with a wide range of desired mechanical responses, including anisotropic, spatially heterogeneous, hierarchical and self-similar designs. Demonstrative application examples in thin, skin-mounted electrophysiological sensors with mechanics precisely matched to the human epidermis and in soft, hydrogel-based vehicles for triggered drug release suggest their broad potential uses in biomedical devices.

  8. Bio-inspired Dynamic Gradients Regulated by Supramolecular Bindings in Receptor-Embedded Hydrogel Matrices.

    PubMed

    Luan, Xinglong; Zhang, Yihe; Wu, Jing; Jonkheijm, Pascal; Li, Guangtao; Jiang, Lei; Huskens, Jurriaan; An, Qi

    2016-08-01

    The kinetics of supramolecular bindings are fundamentally important for molecular motions and spatial-temporal distributions in biological systems, but have rarely been employed in preparing artificial materials. This report proposes a bio-inspired concept to regulate dynamic gradients through the coupled supramolecular binding and diffusion process in receptor-embedded hydrogel matrices. A new type of hydrogel that uses cyclodextrin (CD) as both the gelling moiety and the receptors is prepared as the diffusion matrices. The diffusible guest, 4-aminoazobenzene, quickly and reversibly binds to matrices-bound CD during diffusion and generates steeper gradients than regular diffusion. Weakened bindings induced through UV irradiation extend the gradients. Combined with numerical simulation, these results indicate that the coupled binding-diffusion could be viewed as slowed diffusion, regulated jointly by the binding constant and the equilibrium receptor concentrations, and gradients within a bio-relevant extent of 4 mm are preserved up to 90 h. This report should inspire design strategies of biomedical or cell-culturing materials. PMID:27547643

  9. Soft network composite materials with deterministic and bio-inspired designs

    PubMed Central

    Jang, Kyung-In; Chung, Ha Uk; Xu, Sheng; Lee, Chi Hwan; Luan, Haiwen; Jeong, Jaewoong; Cheng, Huanyu; Kim, Gwang-Tae; Han, Sang Youn; Lee, Jung Woo; Kim, Jeonghyun; Cho, Moongee; Miao, Fuxing; Yang, Yiyuan; Jung, Han Na; Flavin, Matthew; Liu, Howard; Kong, Gil Woo; Yu, Ki Jun; Rhee, Sang Il; Chung, Jeahoon; Kim, Byunggik; Kwak, Jean Won; Yun, Myoung Hee; Kim, Jin Young; Song, Young Min; Paik, Ungyu; Zhang, Yihui; Huang, Yonggang; Rogers, John A.

    2015-01-01

    Hard and soft structural composites found in biology provide inspiration for the design of advanced synthetic materials. Many examples of bio-inspired hard materials can be found in the literature; far less attention has been devoted to soft systems. Here we introduce deterministic routes to low-modulus thin film materials with stress/strain responses that can be tailored precisely to match the non-linear properties of biological tissues, with application opportunities that range from soft biomedical devices to constructs for tissue engineering. The approach combines a low-modulus matrix with an open, stretchable network as a structural reinforcement that can yield classes of composites with a wide range of desired mechanical responses, including anisotropic, spatially heterogeneous, hierarchical and self-similar designs. Demonstrative application examples in thin, skin-mounted electrophysiological sensors with mechanics precisely matched to the human epidermis and in soft, hydrogel-based vehicles for triggered drug release suggest their broad potential uses in biomedical devices. PMID:25782446

  10. Creep-assisted slow crack growth in bio-inspired dental multilayers.

    PubMed

    Du, Jing; Niu, Xinrui; Soboyejo, Wole

    2015-06-01

    Ceramic crown structures under occlusal contact are often idealized as flat multilayered structures that are deformed under Hertzian contact loading. Previous models treated each layer as linear elastic materials and resulted in differences between the measured and predicted critical loads. This paper examines the combined effects of creep (in the adhesive and substrate layers) and creep-assisted slow crack growth (in the ceramic layer) on the contact-induced deformation of bio-inspired, functionally graded multilayer (FGM) structures and the conventional tri-layers. The time-dependent moduli of each of the layers were determined from constant load creep tests. The resulting modulus-time characteristics were modeled using Prony series. These were then incorporated into a finite element model for the computation of stress distributions in the sub-surface regions of the top ceramic layer, in which sub-surface radial cracks, are observed as the clinical failure mode. The time-dependent stresses are incorporated into a slow crack growth (SCG) model that is used to predict the critical loads of the dental multilayers under Hertzian contact loading. The predicted loading rate dependence of the critical loads is shown to be consistent with experimental results. The implications of the results are then discussed for the design of robust dental multilayers. PMID:25771255

  11. Numerical analysis of bio-inspired corrugated airfoil at low Reynolds number

    NASA Astrophysics Data System (ADS)

    Mondal, Partha Protim; Rahman, Md. Masudur; Hasan, A. B. M. Toufique

    2016-07-01

    A numerical study was conducted to investigate the aerodynamic performance of a bio-inspired corrugated airfoil at the chord Reynolds number of Rec=80,000 to explore the potential advantages of such airfoils at low Reynolds numbers. This study represents the transient nature of corrugated airfoils at low Reynolds number where flow is assumed to be laminar, unsteady, incompressible and two dimensional. The simulations include a sharp interface Cartesian grid based meshing employed with laminar viscous model. The flow field surrounding the corrugated airfoil has been analyzed using structured grid Finite Volume Method (FVM) based on Navier-Stokes equation. All parameters used in flow simulation are expressed in non-dimensional quantities for better understanding of flow behavior, regardless of dimensions or the fluid that is used. The simulated results revealed that the corrugated airfoil provides high lift with moderate drag and prevents large scale flow separation at higher angles of attack. This happens due to the negative shear drag produced by the recirculation zones which occurs in the valleys of the corrugated airfoils. The existence of small circulation bubbles sitting in the valleys prevents large scale flow separation thus increasing the aerodynamic performance of the corrugated airfoil.

  12. Bio-inspired bending actuator for controlling conical nose shape using piezoelectric patches.

    PubMed

    Na, Tae-Won; Jung, Jin-Young; Oh, Ii-Kwon

    2014-10-01

    In this paper, a bio-inspired bending actuator was designed and fabricated using piezoelectric patches and cantilever-shaped beam for controlling nose shape. The aim of this study is to investigate the use of the bending actuator. PZT and single crystal PMN-PT actuators were used to generate translational strain and shear stress. The piezoelectric patches were attached on the clamped cantilever beam to convert their translational strains to bending motion of the beam. First, finite element analysis was performed to identify and to make an accurate estimate of the feasibility on the bending actuation by applying various voltages and frequencies. Based on the results of the FEM analysis, the experiments were also performed. Static voltages and dynamic voltages with various frequencies were applied to the bending actuators with PZTs and PMN-PTs, and the rotation angles of the nose connected to the top of bending actuators were measured, respectively. As the results, the bending actuator using PMN-PT patches showed better performances in all cases. With the increases of signal frequency and input voltage, the rotation angle also found to be increased. Especially at the frequency of 5 Hz and input voltage of 600 V, the nose generated the maximum rotation angle of 3.15 degree. PMID:25942810

  13. Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong Composites

    NASA Astrophysics Data System (ADS)

    Han, Yue; Zhang, Xiaohua; Yu, Xueping; Zhao, Jingna; Li, Shan; Liu, Feng; Gao, Peng; Zhang, Yongyi; Zhao, Tong; Li, Qingwen

    2015-06-01

    High performance nanocomposites require well dispersion and high alignment of the nanometer-sized components, at a high mass or volume fraction as well. However, the road towards such composite structure is severely hindered due to the easy aggregation of these nanometer-sized components. Here we demonstrate a big step to approach the ideal composite structure for carbon nanotube (CNT) where all the CNTs were highly packed, aligned, and unaggregated, with the impregnated polymers acting as interfacial adhesions and mortars to build up the composite structure. The strategy was based on a bio-inspired aggregation control to limit the CNT aggregation to be sub 20-50 nm, a dimension determined by the CNT growth. After being stretched with full structural relaxation in a multi-step way, the CNT/polymer (bismaleimide) composite yielded super-high tensile strengths up to 6.27-6.94 GPa, more than 100% higher than those of carbon fiber/epoxy composites, and toughnesses up to 117-192 MPa. We anticipate that the present study can be generalized for developing multifunctional and smart nanocomposites where all the surfaces of nanometer-sized components can take part in shear transfer of mechanical, thermal, and electrical signals.

  14. The tubercles on humpback whales' flippers: application of bio-inspired technology.

    PubMed

    Fish, Frank E; Weber, Paul W; Murray, Mark M; Howle, Laurens E

    2011-07-01

    The humpback whale (Megaptera novaeangliae) is exceptional among the large baleen whales in its ability to undertake aquabatic maneuvers to catch prey. Humpback whales utilize extremely mobile, wing-like flippers for banking and turning. Large rounded tubercles along the leading edge of the flipper are morphological structures that are unique in nature. The tubercles on the leading edge act as passive-flow control devices that improve performance and maneuverability of the flipper. Experimental analysis of finite wing models has demonstrated that the presence of tubercles produces a delay in the angle of attack until stall, thereby increasing maximum lift and decreasing drag. Possible fluid-dynamic mechanisms for improved performance include delay of stall through generation of a vortex and modification of the boundary layer, and increase in effective span by reduction of both spanwise flow and strength of the tip vortex. The tubercles provide a bio-inspired design that has commercial viability for wing-like structures. Control of passive flow has the advantages of eliminating complex, costly, high-maintenance, and heavy control mechanisms, while improving performance for lifting bodies in air and water. The tubercles on the leading edge can be applied to the design of watercraft, aircraft, ventilation fans, and windmills. PMID:21576119

  15. Boundary layer drag reduction research hypotheses derived from bio-inspired surface and recent advanced applications.

    PubMed

    Luo, Yuehao; Yuan, Lu; Li, Jianhua; Wang, Jianshe

    2015-12-01

    Nature has supplied the inexhaustible resources for mankind, and at the same time, it has also progressively developed into the school for scientists and engineers. Through more than four billions years of rigorous and stringent evolution, different creatures in nature gradually exhibit their own special and fascinating biological functional surfaces. For example, sharkskin has the potential drag-reducing effect in turbulence, lotus leaf possesses the self-cleaning and anti-foiling function, gecko feet have the controllable super-adhesion surfaces, the flexible skin of dolphin can accelerate its swimming velocity. Great profits of applying biological functional surfaces in daily life, industry, transportation and agriculture have been achieved so far, and much attention from all over the world has been attracted and focused on this field. In this overview, the bio-inspired drag-reducing mechanism derived from sharkskin is explained and explored comprehensively from different aspects, and then the main applications in different fluid engineering are demonstrated in brief. This overview will inevitably improve the comprehension of the drag reduction mechanism of sharkskin surface and better understand the recent applications in fluid engineering. PMID:26348428

  16. A Wireless Fatigue Monitoring System Utilizing a Bio-Inspired Tree Ring Data Tracking Technique

    PubMed Central

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-01-01

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc. PMID:24603635

  17. Computational analysis of a tip vortex structure shed from a bio-inspired blade

    NASA Astrophysics Data System (ADS)

    Gomez, Sebastian; Gilkey, Lindsay N.; Kaiser, Bryan E.; Poroseva, Svetlana V.

    2013-11-01

    Understanding and predicting a tip vortex structure and its dynamics is of significant importance for all branches of aerodynamics. A particular focus of our research is the rotorcraft performance which is substantially influenced by a tip vortex. A tip vortex also is a major source of energy losses and acoustic noise. In the present study, an impact of a blade shape on a tip vortex structure is analyzed. Simulations are conducted of flows around a rectangular blade and a bio-inspired blade of the same area. An insect wing is chosen as a blade prototype. Indeed, insects developed physical characteristics that reduce energy consumption while permitting sustained and controlled flight at low level of noise. Analysis has been done to determine what insect poses flight characteristics closest to the small rotorcraft design goals. Commercial CFD software STAR-CCM + is used for conducting computations on structured and unstructured grids and for data post-processing. The authors acknowledge support from UNM CARC in a form of access to HPC and from CD-Adapco for providing Star-CCM+ for academic purposes. The first author's work was supported by the New Mexico Space Grant Consortium.

  18. Bio-inspired surface modification of PET for cardiovascular applications: Case study of gelatin.

    PubMed

    Giol, E Diana; Schaubroeck, David; Kersemans, Ken; De Vos, Filip; Van Vlierberghe, Sandra; Dubruel, Peter

    2015-10-01

    An aqueous-based bio-inspired approach was applied to chemically bind a bio compatible and cell-interactive gelatin layer on poly(ethylene terephthalate) (PET) for cardiovascular applications. The protein layer was immobilized after an initial surface activation via a dopamine coating. The individual and synergetic effect of the dopamine deposition procedure and the substrate nature (pristine versus plasma-treated) was investigated via XPS, AFM, SEM and contact angle measurements. Dependent on the applied parameters, the post dopamine coating presented various surface roughnesses ranging between 96 nm and 210 nm. Subsequent gelatin immobilization mostly induced a smoothening effect, but the synergetic influence of the deposition protocol and plasma treatment resulted in different gelatin conformations. In addition, a comprehensive comparative study between chemically-modified (via dopamine) and physically-modified (physisorption) PET with gelatin was developed within the present study. All investigated samples were submitted to preliminary haemocompatibility tests, which clearly indicated the direct link between blood platelet behaviour and final protein arrangement. PMID:26163974

  19. Novel bio-inspired smart control for hazard mitigation of civil structures

    NASA Astrophysics Data System (ADS)

    Kim, Yeesock; Kim, Changwon; Langari, Reza

    2010-11-01

    In this paper, a new bio-inspired controller is proposed for vibration mitigation of smart structures subjected to ground disturbances (i.e. earthquakes). The control system is developed through the integration of a brain emotional learning (BEL) algorithm with a proportional-integral-derivative (PID) controller and a semiactive inversion (Inv) algorithm. The BEL algorithm is based on the neurologically inspired computational model of the amygdala and the orbitofrontal cortex. To demonstrate the effectiveness of the proposed hybrid BEL-PID-Inv control algorithm, a seismically excited building structure equipped with a magnetorheological (MR) damper is investigated. The performance of the proposed hybrid BEL-PID-Inv control algorithm is compared with that of passive, PID, linear quadratic Gaussian (LQG), and BEL control systems. In the simulation, the robustness of the hybrid BEL-PID-Inv control algorithm in the presence of modeling uncertainties as well as external disturbances is investigated. It is shown that the proposed hybrid BEL-PID-Inv control algorithm is effective in improving the dynamic responses of seismically excited building structure-MR damper systems.

  20. Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong Composites.

    PubMed

    Han, Yue; Zhang, Xiaohua; Yu, Xueping; Zhao, Jingna; Li, Shan; Liu, Feng; Gao, Peng; Zhang, Yongyi; Zhao, Tong; Li, Qingwen

    2015-01-01

    High performance nanocomposites require well dispersion and high alignment of the nanometer-sized components, at a high mass or volume fraction as well. However, the road towards such composite structure is severely hindered due to the easy aggregation of these nanometer-sized components. Here we demonstrate a big step to approach the ideal composite structure for carbon nanotube (CNT) where all the CNTs were highly packed, aligned, and unaggregated, with the impregnated polymers acting as interfacial adhesions and mortars to build up the composite structure. The strategy was based on a bio-inspired aggregation control to limit the CNT aggregation to be sub 20-50 nm, a dimension determined by the CNT growth. After being stretched with full structural relaxation in a multi-step way, the CNT/polymer (bismaleimide) composite yielded super-high tensile strengths up to 6.27-6.94 GPa, more than 100% higher than those of carbon fiber/epoxy composites, and toughnesses up to 117-192 MPa. We anticipate that the present study can be generalized for developing multifunctional and smart nanocomposites where all the surfaces of nanometer-sized components can take part in shear transfer of mechanical, thermal, and electrical signals. PMID:26098627

  1. Mechanical properties of a bio-inspired robotic knifefish with an undulatory propulsor.

    PubMed

    Curet, Oscar M; Patankar, Neelesh A; Lauder, George V; MacIver, Malcolm A

    2011-06-01

    South American electric knifefish are a leading model system within neurobiology. Recent efforts have focused on understanding their biomechanics and relating this to their neural processing strategies. Knifefish swim by means of an undulatory fin that runs most of the length of their body, affixed to the belly. Propelling themselves with this fin enables them to keep their body relatively straight while swimming, enabling straightforward robotic implementation with a rigid hull. In this study, we examined the basic properties of undulatory swimming through use of a robot that was similar in some key respects to the knifefish. As we varied critical fin kinematic variables such as frequency, amplitude, and wavelength of sinusoidal traveling waves, we measured the force generated by the robot when it swam against a stationary sensor, and its velocity while swimming freely within a flow tunnel system. Our results show that there is an optimal operational region in the fin's kinematic parameter space. The optimal actuation parameters found for the robotic knifefish are similar to previously observed parameters for the black ghost knifefish, Apteronotus albifrons. Finally, we used our experimental results to show how the force generated by the robotic fin can be decomposed into thrust and drag terms. Our findings are useful for future bio-inspired underwater vehicles as well as for understanding the mechanics of knifefish swimming. PMID:21474864

  2. Bio-inspired in situ crosslinking and mineralization of electrospun collagen scaffolds for bone tissue engineering.

    PubMed

    Dhand, Chetna; Ong, Seow Theng; Dwivedi, Neeraj; Diaz, Silvia Marrero; Venugopal, Jayarama Reddy; Navaneethan, Balchandar; Fazil, Mobashar H U T; Liu, Shouping; Seitz, Vera; Wintermantel, Erich; Beuerman, Roger W; Ramakrishna, Seeram; Verma, Navin K; Lakshminarayanan, Rajamani

    2016-10-01

    Bone disorders are the most common cause of severe long term pain and physical disability, and affect millions of people around the world. In the present study, we report bio-inspired preparation of bone-like composite structures by electrospinning of collagen containing catecholamines and Ca(2+). The presence of divalent cation induces simultaneous partial oxidative polymerization of catecholamines and crosslinking of collagen nanofibers, thus producing mats that are mechanically robust and confer photoluminescence properties. Subsequent mineralization of the mats by ammonium carbonate leads to complete oxidative polymerization of catecholamines and precipitation of amorphous CaCO3. The collagen composite scaffolds display outstanding mechanical properties with Young's modulus approaching the limits of cancellous bone. Biological studies demonstrate that human fetal osteoblasts seeded on to the composite scaffolds display enhanced cell adhesion, penetration, proliferation, differentiation and osteogenic expression of osteocalcin, osteopontin and bone matrix protein when compared to pristine collagen or tissue culture plates. Among the two catecholamines, mats containing norepinephrine displayed superior mechanical, photoluminescence and biological properties than mats loaded with dopamine. These smart multifunctional scaffolds could potentially be utilized to repair and regenerate bone defects and injuries. PMID:27475728

  3. Bio-inspired adaptive feedback error learning architecture for motor control.

    PubMed

    Tolu, Silvia; Vanegas, Mauricio; Luque, Niceto R; Garrido, Jesús A; Ros, Eduardo

    2012-10-01

    This study proposes an adaptive control architecture based on an accurate regression method called Locally Weighted Projection Regression (LWPR) and on a bio-inspired module, such as a cerebellar-like engine. This hybrid architecture takes full advantage of the machine learning module (LWPR kernel) to abstract an optimized representation of the sensorimotor space while the cerebellar component integrates this to generate corrective terms in the framework of a control task. Furthermore, we illustrate how the use of a simple adaptive error feedback term allows to use the proposed architecture even in the absence of an accurate analytic reference model. The presented approach achieves an accurate control with low gain corrective terms (for compliant control schemes). We evaluate the contribution of the different components of the proposed scheme comparing the obtained performance with alternative approaches. Then, we show that the presented architecture can be used for accurate manipulation of different objects when their physical properties are not directly known by the controller. We evaluate how the scheme scales for simulated plants of high Degrees of Freedom (7-DOFs). PMID:22907270

  4. Bio-inspired classifier for road extraction from remote sensing imagery

    NASA Astrophysics Data System (ADS)

    Xu, Jiawei; Wang, Ruisheng; Yue, Shigang

    2014-01-01

    An adaptive approach for road extraction inspired by the mechanism of primary visual cortex (V1) is proposed. The motivation is originated by the characteristics in the receptive field from V1. It has been proved that human or primate visual systems can distinguish useful cues from real scenes effortlessly while traditional computer vision techniques cannot accomplish this task easily. This idea motivates us to design a bio-inspired model for road extraction from remote sensing imagery. The proposed approach is an improved support vector machine (SVM) based on the pooling of feature vectors, using an improved Gaussian radial basis function (RBF) kernel with tuning on synaptic gains. The synaptic gains comprise the feature vectors through an iterative optimization process representing the strength and width of Gaussian RBF kernel. The synaptic gains integrate the excitation and inhibition stimuli based on internal connections from V1. The summation of synaptic gains contributes to pooling of feature vectors. The experimental results verify the correlation between the synaptic gain and classification rules, and then show better performance in comparison with hidden Markov model, SVM, and fuzzy classification approaches. Our contribution is an automatic approach to road extraction without prelabeling and postprocessing work. Another apparent advantage is that our method is robust for images taken even under complex weather conditions such as snowy and foggy weather.

  5. Bio-inspired artificial muscle structure for integrated sensing and actuation

    NASA Astrophysics Data System (ADS)

    Ye, Zhihang; Faisal, Md. Shahnewaz Sabit; Asmatulu, Ramazan; Chen, Zheng

    2015-04-01

    In this paper, a novel artificial muscle/tendon structure is developed for achieving bio-inspired actuation and self-sensing. The hybrid structure consists of a dielectric elastomer (DE) material connected with carbon fibers, which incorporates the built-in sensing and actuation capability of DE and mechanical, electrical interfacing capability of carbon fibers. DEs are light weight artificial muscles that can generate compliant actuation with low power consumption. Carbon fibers act as artificial tendon due to their high electro-conductivity and mechanical strength. PDMS material is used to electrically and mechanically connect the carbon fibers with the DE material. A strip actuator was fabricated to verify the structure design and characterize its actuation and sensing capabilities. A 3M VHB 4905 tape was used as the DE material. To make compliant electrodes on the VHB tape, carbon black was sprayed on the surface of VHB tape. To join the carbon fibers to the VHB tape, PDMS was used as bonding material. Experiments have been conducted to characterize the actuation and sensing capabilities. The actuation tests have shown that the energy efficiency of artificial muscle can reach up to 0.7% and the strain can reach up to 1%. The sensing tests have verified that the structure is capable of self-sensing through the electrical impedance measurement.

  6. Enhanced photoactivities of TiO2 particles induced by bio-inspired micro-nanoscale substrate.

    PubMed

    Gao, Liguo; Wang, Yawei; Yan, Yang; Li, Qun; Hao, Ce; Ma, Tingli

    2016-05-15

    A silicon substrate with bio-inspired micro-nanoscale structure has been fabricated by wet etching, which is used as TiO2 particles supporting substrate and makes them recovery more easily. It has been shown that the structure facilitates TiO2 with large surface area and suppresses light reflection more effectively, which results in a high photocatalytic performance. The photocatalytic and stable performance has been applied on degrading methyl orange (MO). PMID:26928059

  7. Bio-inspired multinuclear copper complexes covalently immobilized on reduced graphene oxide as efficient electrocatalysts for the oxygen reduction reaction.

    PubMed

    Xi, Yue-Ting; Wei, Ping-Jie; Wang, Ru-Chun; Liu, Jin-Gang

    2015-05-01

    Inspired by the multicopper active site of laccase, which efficiently catalyzes the oxygen reduction reaction (ORR), herein we report a novel bio-inspired ORR catalyst composed of a multinuclear copper complex that was immobilized on the surface of reduced graphene oxide (rGO) via the covalently grafted triazole-dipyridine (TADPy) dinucleating ligand. This rGO-TADPyCu catalyst exhibited high ORR activity and superior long-term stability compared to Pt/C in alkaline media. PMID:25825826

  8. Functional architectures based on self-assembly of bio-inspired dipeptides: Structure modulation and its photoelectronic applications.

    PubMed

    Chen, Chengjun; Liu, Kai; Li, Junbai; Yan, Xuehai

    2015-11-01

    Getting inspiration from nature and further developing functional architectures provides an effective way to design innovative materials and systems. Among bio-inspired materials, dipeptides and its self-assembled architectures with functionalities have recently been the subject of intensive studies. However, there is still a great challenge to explore its applications likely due to the lack of effective adaptation of their self-assembled structures as well as a lack of understanding of the self-assembly mechanisms. In this context, taking diphenylalanine (FF, a core recognition motif for molecular self-assembly of the Alzheimer's β-amyloid polypeptides) as a model of bio-inspired dipeptides, recent strategies on modulation of dipeptide-based architectures were introduced with regard to both covalent (architectures modulation by coupling functional groups) and non-covalent ways (controlled architectures by different assembly pathways). Then, applications are highlighted in some newly emerging fields of innovative photoelectronic devices and materials, such as artificial photosynthetic systems for renewable solar energy storage and renewable optical waveguiding materials for optoelectronic devices. At last, the challenges and future perspectives of these bio-inspired dipeptides are also addressed. PMID:26365127

  9. Superhydro-oleophobic bio-inspired polydimethylsiloxane micropillared surface via FDTS coating/blending approaches

    NASA Astrophysics Data System (ADS)

    Pan, Zihe; Shahsavan, Hamed; Zhang, Wei; Yang, Fut K.; Zhao, Boxin

    2015-01-01

    In this work we render superhydro-oleophobic properties to the surface of polydimethylsiloxane (PDMS) elastomer through bio-inspired micropillar surface and chemical modification with a fluorosilane polymer, trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS). Two different chemical modification approaches were applied on both flat and micropillar PDMS: (1) vapor deposition of FDTS on cured PDMS surface, and (2) blending FDTS with the liquid PDMS precursor before curing. Comparative studies of the water and oil contact angles on the neat and FDTS-modified PDMS (both flat and micropillar) indicated that superhydro-oleophobicity was delivered by a combination of FDTS chemistry and micropillar geometry. FDTS-blended PDMS micropillar displayed better oleophobicity with an oil contact angle of ∼141° than FDTS-coated PDMS micropillar (∼115°). In contrast to the smooth surface of FDTS-blended PDMS micropillar, rough surface with some structure defects were found on the FDTS-coated micropillar surface caused by the vapor deposition process; the surface defects might be responsible for the observed low oleophobicity of FDTS-coated PDMS micropillar. Superhydrophobicity of FDTS-blended PDMS micropillar in terms of water contact angles was found to be independent of the quantity of FDTS. However, the oleophobicity of FDTS-blended PDMS micropillar was found to be dependent of the quantity of FDTS; with the increased weight concentration of FDTS in PDMS, the oils contact angle first increased and then leveled out at a finite concentration. FTIR and XPS were applied to analyze surface chemistry information suggesting the blended FDTS segregated from bulk PDMS and enriched at the surface to reduce surface tension so as to make surface super-oleophobic.

  10. A bio-inspired real-time capable artificial lateral line system for freestream flow measurements.

    PubMed

    Abels, C; Qualtieri, A; De Vittorio, M; Megill, W M; Rizzi, F

    2016-06-01

    To enhance today's artificial flow sensing capabilities in aerial and underwater robotics, future robots could be equipped with a large number of miniaturized sensors distributed over the surface to provide high resolution measurement of the surrounding fluid flow. In this work we show a linear array of closely separated bio-inspired micro-electro-mechanical flow sensors whose sensing mechanism is based on a piezoresistive strain-gauge along a stress-driven cantilever beam, mimicking the biological superficial neuromasts found in the lateral line organ of fishes. Aiming to improve state-of-the-art flow sensing capability in autonomously flying and swimming robots, our artificial lateral line system was designed and developed to feature multi-parameter freestream flow measurements which provide information about (1) local flow velocities as measured by the signal amplitudes from the individual cantilevers as well as (2) propagation velocity, (3) linear forward/backward direction along the cantilever beam orientation and (4) periodicity of pulses or pulse trains determined by cross-correlating sensor signals. A real-time capable cross-correlation procedure was developed which makes it possible to extract freestream flow direction and velocity information from flow fluctuations. The computed flow velocities deviate from a commercial system by 0.09 m s(-1) at 0.5 m s(-1) and 0.15 m s(-1) at 1.0 m s(-1) flow velocity for a sampling rate of 240 Hz and a sensor distance of 38 mm. Although experiments were performed in air, the presented flow sensing system can be applied to underwater vehicles as well, once the sensors are embedded in a waterproof micro-electro-mechanical systems package. PMID:27257144

  11. A nonlinear mechanics model of bio-inspired hierarchical lattice materials consisting of horseshoe microstructures

    NASA Astrophysics Data System (ADS)

    Ma, Qiang; Cheng, Huanyu; Jang, Kyung-In; Luan, Haiwen; Hwang, Keh-Chih; Rogers, John A.; Huang, Yonggang; Zhang, Yihui

    2016-05-01

    Development of advanced synthetic materials that can mimic the mechanical properties of non-mineralized soft biological materials has important implications in a wide range of technologies. Hierarchical lattice materials constructed with horseshoe microstructures belong to this class of bio-inspired synthetic materials, where the mechanical responses can be tailored to match the nonlinear J-shaped stress-strain curves of human skins. The underlying relations between the J-shaped stress-strain curves and their microstructure geometry are essential in designing such systems for targeted applications. Here, a theoretical model of this type of hierarchical lattice material is developed by combining a finite deformation constitutive relation of the building block (i.e., horseshoe microstructure), with the analyses of equilibrium and deformation compatibility in the periodical lattices. The nonlinear J-shaped stress-strain curves and Poisson ratios predicted by this model agree very well with results of finite element analyses (FEA) and experiment. Based on this model, analytic solutions were obtained for some key mechanical quantities, e.g., elastic modulus, Poisson ratio, peak modulus, and critical strain around which the tangent modulus increases rapidly. A negative Poisson effect is revealed in the hierarchical lattice with triangular topology, as opposed to a positive Poisson effect in hierarchical lattices with Kagome and honeycomb topologies. The lattice topology is also found to have a strong influence on the stress-strain curve. For the three isotropic lattice topologies (triangular, Kagome and honeycomb), the hierarchical triangular lattice material renders the sharpest transition in the stress-strain curve and relative high stretchability, given the same porosity and arc angle of horseshoe microstructure. Furthermore, a demonstrative example illustrates the utility of the developed model in the rapid optimization of hierarchical lattice materials for

  12. Transportation network with fluctuating input/output designed by the bio-inspired Physarum algorithm.

    PubMed

    Watanabe, Shin; Takamatsu, Atsuko

    2014-01-01

    In this paper, we propose designing transportation network topology and traffic distribution under fluctuating conditions using a bio-inspired algorithm. The algorithm is inspired by the adaptive behavior observed in an amoeba-like organism, plasmodial slime mold, more formally known as plasmodium of Physarum plycephalum. This organism forms a transportation network to distribute its protoplasm, the fluidic contents of its cell, throughout its large cell body. In this process, the diameter of the transportation tubes adapts to the flux of the protoplasm. The Physarum algorithm, which mimics this adaptive behavior, has been widely applied to complex problems, such as maze solving and designing the topology of railroad grids, under static conditions. However, in most situations, environmental conditions fluctuate; for example, in power grids, the consumption of electric power shows daily, weekly, and annual periodicity depending on the lifestyles or the business needs of the individual consumers. This paper studies the design of network topology and traffic distribution with oscillatory input and output traffic flows. The network topology proposed by the Physarum algorithm is controlled by a parameter of the adaptation process of the tubes. We observe various rich topologies such as complete mesh, partial mesh, Y-shaped, and V-shaped networks depending on this adaptation parameter and evaluate them on the basis of three performance functions: loss, cost, and vulnerability. Our results indicate that consideration of the oscillatory conditions and the phase-lags in the multiple outputs of the network is important: The building and/or maintenance cost of the network can be reduced by introducing the oscillating condition, and when the phase-lag among the outputs is large, the transportation loss can also be reduced. We use stability analysis to reveal how the system exhibits various topologies depending on the parameter. PMID:24586616

  13. Interconversion of CO2 and formic acid by bio-inspired Ir complexes with pendent bases.

    PubMed

    Fujita, Etsuko; Muckerman, James T; Himeda, Yuichiro

    2013-01-01

    Recent investigations of the interconversion of CO2 and formic acid using Ru, Ir and Fe complexes are summarized in this review. During the past several years, both the reaction rates and catalyst stabilities have been significantly improved. Remarkably, the interconversion (i.e., reversibility) has also been achieved under mild conditions in environmentally benign water solvent by slightly changing the pH of the aqueous solution. Only a few catalysts seem to reflect a bio-inspired design such as the use of proton responsive ligands, ligands with pendent bases or acids for a second-coordination-sphere interaction, electroresponsive ligands, and/or ligands having a hydrogen bonding function with a solvent molecule or an added reagent. The most successful of these is an iridium dinuclear complex catalyst that at least has the first three of these characteristics associated with its bridging ligand. By utilizing an acid/base equilibrium for proton removal, the ligand becomes a strong electron donor, resulting in Ir(I) character with a vacant coordination site at each metal center in slightly basic solution. Complemented by DFT calculations, kinetic studies of the rates of formate production using a related family of Ir complexes with and without such functions on the ligand reveal that the rate-determining step for the CO2 hydrogenation is likely to be H2 addition through heterolytic cleavage involving a "proton relay" through the pendent base. The dehydrogenation of formic acid, owing to the proton responsive ligands changing character under slightly acidic pH conditions, is likely to occur by a mechanism with a different rate-determining step. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. PMID:23174332

  14. Classifying continuous, real-time e-nose sensor data using a bio-inspired spiking network modelled on the insect olfactory system.

    PubMed

    Diamond, A; Schmuker, M; Berna, A Z; Trowell, S; Nowotny, Thomas

    2016-04-01

    In many application domains, conventional e-noses are frequently outperformed in both speed and accuracy by their biological counterparts. Exploring potential bio-inspired improvements, we note a number of neuronal network models have demonstrated some success in classifying static datasets by abstracting the insect olfactory system. However, these designs remain largely unproven in practical settings, where sensor data is real-time, continuous, potentially noisy, lacks a precise onset signal and accurate classification requires the inclusion of temporal aspects into the feature set. This investigation therefore seeks to inform and develop the potential and suitability of biomimetic classifiers for use with typical real-world sensor data. Taking a generic classifier design inspired by the inhibition and competition in the insect antennal lobe, we apply it to identifying 20 individual chemical odours from the timeseries of responses of metal oxide sensors. We show that four out of twelve available sensors and the first 30 s (10%) of the sensors' continuous response are sufficient to deliver 92% accurate classification without access to an odour onset signal. In contrast to previous approaches, once training is complete, sensor signals can be fed continuously into the classifier without requiring discretization. We conclude that for continuous data there may be a conceptual advantage in using spiking networks, in particular where time is an essential component of computation. Classification was achieved in real time using a GPU-accelerated spiking neural network simulator developed in our group. PMID:26891474

  15. Bio-Inspired Photon Absorption and Energy Transfer for Next Generation Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Magsi, Komal

    Nature's solar energy harvesting system, photosynthesis, serves as a model for photon absorption, spectra broadening, and energy transfer. Photosynthesis harvests light far differently than photovoltaic cells. These differences offer both engineering opportunity and scientific challenges since not all of the natural photon absorption mechanisms have been understood. In return, solar cells can be a very sensitive probe for the absorption characteristics of molecules capable of transferring charge to a conductive interface. The objective of this scientific work is the advancement of next generation photovoltaics through the development and application of natural photo-energy transfer processes. Two scientific methods were used in the development and application of enhancing photon absorption and transfer. First, a detailed analysis of photovoltaic front surface fluorescent spectral modification and light scattering by hetero-structure was conducted. Phosphor based spectral down-conversion is a well-known laser technology. The theoretical calculations presented here indicate that parasitic losses and light scattering within the spectral range are large enough to offset any expected gains. The second approach for enhancing photon absorption is based on bio-inspired mechanisms. Key to the utilization of these natural processes is the development of a detailed scientific understanding and the application of these processes to cost effective systems and devices. In this work both aspects are investigated. Dye type solar cells were prepared and tested as a function of Chlorophyll (or Sodium-Copper Chlorophyllin) and accessory dyes. Forster has shown that the fluorescence ratio of Chlorophyll is modified and broadened by separate photon absorption (sensitized absorption) through interaction with nearby accessory pigments. This work used the dye type solar cell as a diagnostic tool by which to investigate photon absorption and photon energy transfer. These experiments shed

  16. Electrowetting-Controlled and Electrically-Tunable Bio-Inspired Micro/Nanostructures and Optofluidic Devices

    NASA Astrophysics Data System (ADS)

    Manakasettharn, Supone

    Many man-made structures and devices have been inspired by the ingenious structures, mechanisms, properties, and functions of plants and animals. This work has been inspired by a number of unique properties, which biological organisms possess such as dynamic tunable iridescence, self-cleaning properties, and brilliant structural color. The objective of this work is to model, design, fabricate, and characterize novel bio-inspired micro-/nanostructures and optofluidic devices. To conceptually mimic the iridescence of cephalopods, microflowers have been modeled and designed based on elasto-capillary bending, which is the interplay between the elastic energy of petals and the capillary energy of a liquid droplet, which is used to actuate petal movement. After microfabrication of the polycrystalline Si microflowers, two methods of petal actuation have been demonstrated---one by volume change of the water droplet and the other by change of water contact angle on the petals using the electrowetting process. The experimental results are in good agreement with a theoretical model. By taking into account the self-cleaning properties of lotus leaves, transparent Ta2O5 nanostructured thin films have been fabricated using a multi-step anodization process of sputter-deposited Al-Ta bilayers on a quartz substrate. The films then have been made superhydrophobic by using a combination of nanostructures, called nanograss, along with the deposition of hydrophobic coatings. The films also have been characterized by measuring water contact angles and by obtaining optical transmittance spectra and SEM micrographs. The measured contact angles and transmittance spectra are in good agreement with theoretical calculations. Inspired by biological nanostructured surfaces possessing structural color and wettability control, reflective Ta2O5 nanostructured thin films have been fabricated using the multi-step anodization process of sputter-deposited Al-Ta bilayers on a Si substrate. The films

  17. An IPMC-enabled bio-inspired bending/twisting fin for underwater applications

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar; Hubbard, Joel J.; Fleming, Maxwell; Pugal, David; Kim, Sungjun; Kim, Kwang J.; Leang, Kam K.

    2013-01-01

    This paper discusses the design, fabrication, and characterization of an ionic polymer-metal composite (IPMC) actuator-based bio-inspired active fin capable of bending and twisting motion. It is pointed out that IPMC strip actuators are used in the simple cantilever configuration to create simple bending (flapping-like) motion for propulsion in underwater autonomous systems. However, the resulting motion is a simple 1D bending and performance is rather limited. To enable more complex deformation, such as the flapping (pitch and heaving) motion of real pectoral and caudal fish fins, a new approach which involves molding or integrating IPMC actuators into a soft boot material to create an active control surface (called a ‘fin’) is presented. The fin can be used to realize complex deformation depending on the orientation and placement of the actuators. In contrast to previously created IPMCs with patterned electrodes for the same purpose, the proposed design avoids (1) the more expensive process of electroless plating platinum all throughout the surface of the actuator and (2) the need for specially patterning the electrodes. Therefore, standard shaped IPMC actuators such as those with rectangular dimensions with varying thicknesses can be used. One unique advantage of the proposed structural design is that custom shaped fins and control surfaces can be easily created without special materials processing. The molding process is cost effective and does not require functionalizing or ‘activating’ the boot material similar to creating IPMCs. For a prototype fin (90 mm wide × 60 mm long × 1.5 mm thick), the measured maximum tip displacement was approximately 44 mm and the twist angle of the fin exceeded 10°. Lift and drag measurements in water where the prototype fin with an airfoil profile was dragged through water at a velocity of 21 cm s-1 showed that the lift and drag forces can be affected by controlling the IPMCs embedded into the fin structure. These

  18. Issues in Applying Bio-Inspiration, Cognitive Critical Mass and Developmental-Inspired Principles to Advanced Intelligent Systems

    NASA Astrophysics Data System (ADS)

    Berg-Cross, Gary; Samsonovich, Alexei V.

    This Chapter summarizes ideas presented at the special PerMIS 2008 session on Biological Inspiration for Intelligent Systems. Bio-inspired principles of development and evolution are a special part of the bio-models and principles that can be used to improve intelligent systems and related artifacts. Such principles are not always explicit. They represent an alternative to incremental engineering expansion using new technology to replicate human intelligent capabilities. They are more evident in efforts to replicate and produce a “critical mass” of higher cognitive functions of the human mind or their emergence through cognitive developmental robotics (DR) and self-regulated learning (SRL). DR approaches takes inspiration from natural processes, so that intelligently engineered systems may create solutions to problems in ways similar to what we hypothesize is occurring with biologics in their natural environment. This Chapter discusses how an SRL-based approach to bootstrap a “critical mass” can be assessed by a set of cognitive tests. It also uses a three-level bio-inspired framework to illustrate methodological issues in DR research. The approach stresses the importance of using bio-realistic developmental principles to guide and constrain research. Of particular importance is keeping models and implementation separate to avoid the possible of falling into a Ptolemaic paradigm that may lead to endless tweaking of models. Several of Lungarella's design principles [36] for developmental robotics are discussed as constraints on intelligence as it emerges from an ecologically balanced, three-way interaction between an agents' control systems, physical embodiment, and the external environment. The direction proposed herein is to explore such principles to avoid slavish following of superficial bio-inspiration. Rather we should proceed with a mature and informed developmental approach using developmental principles based on our incremental understanding of how

  19. In situ synthesis of lead sulfide nanoclusters on eggshell membrane fibers by an ambient bio-inspired technique

    NASA Astrophysics Data System (ADS)

    Su, Huilan; Han, Jie; Wang, Na; Dong, Qun; Zhang, Di; Zhang, Chunfu

    2008-02-01

    An ambient aqueous soakage technique is successfully developed to prepare PbS nanoclusters on eggshell membrane (ESM) fibers containing some active functional groups (hydroxyl, amine, imine, etc). Based on the biomaterial ESM serving as the reactive substrate and some ESM biomacromolecules acting as the surfactant, PbS nanocrystallites are in situ formed and further assembled into well-distributed nanoparticle aggregations. This moderate bio-inspired strategy would be of great value in preparing novel functional nanomaterials. The as-prepared hybrid PbS/ESM nanocomposites could have great potential for applications in semiconductor industries, optoelectronic fields, and nanostructured devices.

  20. Operant conditioning: a minimal components requirement in artificial spiking neurons designed for bio-inspired robot's controller

    PubMed Central

    Cyr, André; Boukadoum, Mounir; Thériault, Frédéric

    2014-01-01

    In this paper, we investigate the operant conditioning (OC) learning process within a bio-inspired paradigm, using artificial spiking neural networks (ASNN) to act as robot brain controllers. In biological agents, OC results in behavioral changes learned from the consequences of previous actions, based on progressive prediction adjustment from rewarding or punishing signals. In a neurorobotics context, virtual and physical autonomous robots may benefit from a similar learning skill when facing unknown and unsupervised environments. In this work, we demonstrate that a simple invariant micro-circuit can sustain OC in multiple learning scenarios. The motivation for this new OC implementation model stems from the relatively complex alternatives that have been described in the computational literature and recent advances in neurobiology. Our elementary kernel includes only a few crucial neurons, synaptic links and originally from the integration of habituation and spike-timing dependent plasticity as learning rules. Using several tasks of incremental complexity, our results show that a minimal neural component set is sufficient to realize many OC procedures. Hence, with the proposed OC module, designing learning tasks with an ASNN and a bio-inspired robot context leads to simpler neural architectures for achieving complex behaviors. PMID:25120464

  1. Operant conditioning: a minimal components requirement in artificial spiking neurons designed for bio-inspired robot's controller.

    PubMed

    Cyr, André; Boukadoum, Mounir; Thériault, Frédéric

    2014-01-01

    In this paper, we investigate the operant conditioning (OC) learning process within a bio-inspired paradigm, using artificial spiking neural networks (ASNN) to act as robot brain controllers. In biological agents, OC results in behavioral changes learned from the consequences of previous actions, based on progressive prediction adjustment from rewarding or punishing signals. In a neurorobotics context, virtual and physical autonomous robots may benefit from a similar learning skill when facing unknown and unsupervised environments. In this work, we demonstrate that a simple invariant micro-circuit can sustain OC in multiple learning scenarios. The motivation for this new OC implementation model stems from the relatively complex alternatives that have been described in the computational literature and recent advances in neurobiology. Our elementary kernel includes only a few crucial neurons, synaptic links and originally from the integration of habituation and spike-timing dependent plasticity as learning rules. Using several tasks of incremental complexity, our results show that a minimal neural component set is sufficient to realize many OC procedures. Hence, with the proposed OC module, designing learning tasks with an ASNN and a bio-inspired robot context leads to simpler neural architectures for achieving complex behaviors. PMID:25120464

  2. Bio-inspired, subwavelength surface structures to control reflectivity, transmission, and scattering in the infrared

    NASA Astrophysics Data System (ADS)

    Lora Gonzalez, Federico

    Controlling the reflection of visible and infrared (IR) light at interfaces is extremely important to increase the power efficiency and performance of optics, electro-optical and (thermo)photovoltaic systems. The eye of the moth has evolved subwavelength protuberances that increase light transmission into the eye tissue and prevent reflection. The subwavelength protuberances effectively grade the refractive index from that of air (n=1) to that of the tissue (n=1.4), making the interface gradual, suppressing reflection. In theory, the moth-eye (ME) structures can be implemented with any material platform to achieve an antireflectance effect by scaling the pitch and size of protuberances for the wavelength range of interest. In this work, a bio-inspired, scalable and substrate-independent surface modification protocol was developed to realize broadband antireflective structures based on the moth-eye principle. Quasi-ordered ME arrays were fabricated in IR relevant materials using a colloidal lithography method to achieve highly efficient, omni-directional transmission of mid and far infrared (IR) radiation. The effect of structure height and aspect ratio on transmittance and scattering is explored, with discussion on experimental techniques and effective medium theory (EMT). The highest aspect ratio structures (AR = 9.4) achieved peak single-side transmittance of 98%, with >85% transmission for lambda = 7--30 microns. A detailed photon balance constructed by transmission, forward scattering, specular reflection and diffuse reflection measurements to quantify optical losses due to near-field effects will be discussed. In addition, angle-dependent transmission measurements showed that moth-eye structures provide superior antireflective properties compared to unstructured interfaces over a wide angular range (0--60° incidence). Finally, subwavelength ME structures are incorporated on a Si substrate to enhance the absorption of near infrared (NIR) light in PtSi films to

  3. LINEBACkER: Bio-inspired Data Reduction Toward Real Time Network Traffic Analysis

    SciTech Connect

    Teuton, Jeremy R.; Peterson, Elena S.; Nordwall, Douglas J.; Akyol, Bora A.; Oehmen, Christopher S.

    2013-09-28

    Abstract—One essential component of resilient cyber applications is the ability to detect adversaries and protect systems with the same flexibility adversaries will use to achieve their goals. Current detection techniques do not enable this degree of flexibility because most existing applications are built using exact or regular-expression matching to libraries of rule sets. Further, network traffic defies traditional cyber security approaches that focus on limiting access based on the use of passwords and examination of lists of installed or downloaded programs. These approaches do not readily apply to network traffic occurring beyond the access control point, and when the data in question are combined control and payload data of ever increasing speed and volume. Manual analysis of network traffic is not normally possible because of the magnitude of the data that is being exchanged and the length of time that this analysis takes. At the same time, using an exact matching scheme to identify malicious traffic in real time often fails because the lists against which such searches must operate grow too large. In this work, we introduce an alternative method for cyber network detection based on similarity-measuring algorithms for gene sequence analysis. These methods are ideal because they were designed to identify similar but nonidentical sequences. We demonstrate that our method is generally applicable to the problem of network traffic analysis by illustrating its use in two different areas both based on different attributes of network traffic. Our approach provides a logical framework for organizing large collections of network data, prioritizing traffic of interest to human analysts, and makes it possible to discover traffic signatures without the bias introduced by expert-directed signature generation. Pattern recognition on reduced representations of network traffic offers a fast, efficient, and more robust way to detect anomalies.

  4. Fmoc-modified amino acids and short peptides: simple bio-inspired building blocks for the fabrication of functional materials.

    PubMed

    Tao, Kai; Levin, Aviad; Adler-Abramovich, Lihi; Gazit, Ehud

    2016-07-11

    Amino acids and short peptides modified with the 9-fluorenylmethyloxycarbonyl (Fmoc) group possess eminent self-assembly features and show distinct potential for applications due to the inherent hydrophobicity and aromaticity of the Fmoc moiety which can promote the association of building blocks. Given the extensive study and numerous publications in this field, it is necessary to summarize the recent progress concerning these important bio-inspired building blocks. Therefore, in this review, we explore the self-organization of this class of functional molecules from three aspects, i.e., Fmoc-modified individual amino acids, Fmoc-modified di- and tripeptides, and Fmoc-modified tetra- and pentapeptides. The relevant properties and applications related to cell cultivation, bio-templating, optical, drug delivery, catalytic, therapeutic and antibiotic properties are subsequently summarized. Finally, some existing questions impeding the development of Fmoc-modified simple biomolecules are discussed, and corresponding strategies and outlooks are suggested. PMID:27115033

  5. Bio-inspired surfactant assisted nano-catalyst impregnation of Solid-Oxide Fuel Cell (SOFC) electrodes

    DOE PAGESBeta

    Ozmen, Ozcan; Zondlo, John W.; Lee, Shiwoo; Gerdes, Kirk; Sabolsky, Edward M.

    2015-11-02

    A bio-inspired surfactant was utilized to assist in the efficient impregnation of a nano-CeO₂ catalyst throughout both porous Solid Oxide Fuel Cells (SOFC’s) electrodes simultaneously. The process included the initial modification of electrode pore walls with a polydopamine film. The cell was then submersed into a cerium salt solution. The amount of nano-CeO₂ deposited per impregnation step increased by 3.5 times by utilizing this two-step protocol in comparison to a conventional drip impregnation method. The impregnated cells exhibited a 20% higher power density than a baseline cell without the nano-catalyst at 750°C (using humid H₂ fuel).

  6. Bio-inspired metal-coordination dynamics: A unique tool for engineering novel properties in soft matter systems

    NASA Astrophysics Data System (ADS)

    Grindy, Scott; Li, Qiaochu; Halim, Abigail; Learsch, Robert; Holten-Andersen, Niels

    2015-03-01

    In soft material systems, materials properties are generally governed by transient, dynamic interactions of many types over many hierarchal length- and time-scales. However, explicit control over these dynamics is not always possible, leaving open questions into how transient interactions can be exploited to design soft materials with unique and exceptional properties. Inspired by the adhesive chemistry and tough character of mussel byssal threads, we present several studies on both the mechanical properties of soft materials and templated crystallization kinetics to show the diverse array of materials properties that can be generated using bio-inspired metal-coordination. By studying our model systems, we can determine the explicit effects of metal-coordination dynamics on various bulk properties, further adding to the set of tools we can use to design soft material systems.

  7. Water repellent/wetting characteristics of various bio-inspired morphologies and fluid drag reduction testing research.

    PubMed

    Luo, Yuehao; Song, Wen; Wang, Xudong

    2016-03-01

    It is well-known that the bio-inspired sharkskin covering the original pattern has the apparent drag reduction function in the turbulent flowing stations, which can be regarded as "sharkskin effect", and it has progressively been put application into the fluid engineering with obtaining great profits. In this paper, the anisotropic wetting phenomena on sharkskin are discovered, the contact angles and rolling angles on different orientations are not the same. In addition, the hydrodynamic experiments on different sharkskin surfaces are conducted, and the experimental results illustrate that the super-hydrophobic and drag-reducing properties on deformed biological surfaces are improved to some extent compared to the original morphology, which has important significance to expand its practical applications. PMID:26760225

  8. Implementation of a cellular neural network-based segmentation algorithm on the bio-inspired vision system

    NASA Astrophysics Data System (ADS)

    Karabiber, Fethullah; Grassi, Giuseppe; Vecchio, Pietro; Arik, Sabri; Yalcin, M. Erhan

    2011-01-01

    Based on the cellular neural network (CNN) paradigm, the bio-inspired (bi-i) cellular vision system is a computing platform consisting of state-of-the-art sensing, cellular sensing-processing and digital signal processing. This paper presents the implementation of a novel CNN-based segmentation algorithm onto the bi-i system. The experimental results, carried out for different benchmark video sequences, highlight the feasibility of the approach, which provides a frame rate of about 26 frame/sec. Comparisons with existing CNN-based methods show that, even though these methods are from two to six times faster than the proposed one, the conceived approach is more accurate and, consequently, represents a satisfying trade-off between real-time requirements and accuracy.

  9. Flexible readout and integration sensor (FRIS): a bio-inspired, system-on-chip, event-based readout architecture

    NASA Astrophysics Data System (ADS)

    Lin, Joseph H.; Pouliquen, Philippe O.; Andreou, Andreas G.; Goldberg, Arnold C.; Rizk, Charbel G.

    2012-06-01

    We present a bio-inspired system-on-chip focal plane readout architecture which at the system level, relies on an event based sampling scheme where only pixels within a programmable range of photon flux rates are output. At the pixel level, a one bit oversampled analog-to-digital converter together with a decimator allows for the quantization of signals up to 26 bits. Furthermore, digital non-uniformity correction of both gain and offset errors is applied at the pixel level prior to readout. We report test results for a prototype array fabricated in a standard 90nm CMOS process. Tests performed at room and cryogenic temperatures demonstrate the capability to operate at a temporal noise ratio as low as 1.5, an electron well capacity over 100Ge-, and an ADC LSB down to 1e-.

  10. Bio-inspired synthesis and laser processing of nanostructured barium titanate thin films: implications for uncooled IR sensor development

    NASA Astrophysics Data System (ADS)

    Livingston, F. E.; Sarney, W. L.; Niesz, K.; Ould-Ely, T.; Tao, A. R.; Morse, D. E.

    2009-05-01

    The Army requires passive uncooled IR sensors for use in numerous vehicle and weapons platforms, including driver vision enhancement (DVE), rifle sights, seeker munitions, and unattended ground sensors (UGSs) and unattended aerial vehicles (UAVs). Recent advances in bio-inspired/biomimetic nanomaterials synthesis, laser material processing, and sensor design and performance testing, offer the opportunity to create uncooled IR detector focal-plane arrays with improved sensitivity, low thermal mass, and fast response times, along with amenability to low-cost, rapid prototype manufacture. We are exploring the use of genotype-inspired, digitally-scripted laser direct-write techniques, in conjunction with the kinetically controlled catalytic process for the growth of nanostructured multimetallic perovskites, to develop a novel approach to the fabrication of precision patterned 2-D focal-plane arrays of pyroelectric perovskite-based materials. The bio-inspired growth of nanostructured, multimetallic perovskite thin-films corresponds to the use of kinetically controlled vapor diffusion for the slow growth of pure, highly crystalline 6-nm barium titanate (BaTiO3) nanoparticles. This unique vapor-diffusion sol-gel route enables the formation of stoichiometric cubic-phase nanoparticles at room temperature and ambient pressure in the absence of a structure-directing template. Novel laser direct-write processing and synchronized electro-optic pulse modulation techniques have been utilized to induce site-selective, patterned phase transformation of microscale aggregates of the BaTiO3 nanoparticles from the non-pyroelectric cubic polymorph to the pyroelectric tetragonal polymorph. This paper reports on our initial collaborative investigations, including comprehensive structural characterization (XRD, TEM, and SEM) of the BaTiO3 nanoparticles and thin-films, along with preliminary laser-induced phase transformation results.

  11. Effect of pre-tension on the peeling behavior of a bio-inspired nano-film and a hierarchical adhesive structure

    NASA Astrophysics Data System (ADS)

    Peng, Zhilong; Chen, Shaohua

    2012-10-01

    Inspired by the reversible adhesion behaviors of geckos, the effects of pre-tension in a bio-inspired nano-film and a hierarchical structure on adhesion are studied theoretically. In the case with a uniformly distributing pre-tension in a spatula-like nano-film under peeling, a closed-form solution to a critical peeling angle is derived, below or above which the peel-off force is enhanced or reduced, respectively, compared with the case without pre-tension. The effects of a non-uniformly distributing pre-tension on adhesion are further investigated for both a spatula-like nano-film and a hierarchical structure-like gecko's seta. Compared with the case without pre-tension, the pre-tension, no matter uniform or non-uniform, can increase the adhesion force not only for the spatula-like nano-film but also for the hierarchical structure at a small peeling angle, while decrease it at a relatively large peeling angle. Furthermore, if the pre-tension is large enough, the effective adhesion energy of a hierarchical structure tends to vanish at a critical peeling angle, which results in spontaneous detachment of the hierarchical structure from the substrate. The present theoretical predictions can not only give some explanations on the existing experimental observation that gecko's seta always detaches at a specific angle and no apparent adhesion force can be detected above the critical angle but also provide a deep understanding for the reversible adhesion mechanism of geckos and be helpful to the design of biomimetic reversible adhesives.

  12. Bio-inspired Optimal Locomotion Reconfigurability of Quadruped Rovers using Central Pattern Generators

    NASA Astrophysics Data System (ADS)

    Bohra, Murtaza

    Legged rovers are often considered as viable solutions for traversing unknown terrain. This work addresses the optimal locomotion reconfigurability of quadruped rovers, which consists of obtaining optimal locomotion modes, and transitioning between them. A 2D sagittal plane rover model is considered based on a domestic cat. Using a Genetic Algorithm, the gait, pose and control variables that minimize torque or maximize speed are found separately. The optimization approach takes into account the elimination of leg impact, while considering the entire variable spectrum. The optimal solutions are consistent with other works on gait optimization, and are similar to gaits found in quadruped animals as well. An online model-free gait planning framework is also implemented, that is based on Central Pattern Generators is implemented. It is used to generate joint and control trajectories for any arbitrarily varying speed profile, and shown to regulate locomotion transition and speed modulation, both endogenously and continuously.

  13. Comparing Neuromorphic Solutions in Action: Implementing a Bio-Inspired Solution to a Benchmark Classification Task on Three Parallel-Computing Platforms.

    PubMed

    Diamond, Alan; Nowotny, Thomas; Schmuker, Michael

    2015-01-01

    Neuromorphic computing employs models of neuronal circuits to solve computing problems. Neuromorphic hardware systems are now becoming more widely available and "neuromorphic algorithms" are being developed. As they are maturing toward deployment in general research environments, it becomes important to assess and compare them in the context of the applications they are meant to solve. This should encompass not just task performance, but also ease of implementation, speed of processing, scalability, and power efficiency. Here, we report our practical experience of implementing a bio-inspired, spiking network for multivariate classification on three different platforms: the hybrid digital/analog Spikey system, the digital spike-based SpiNNaker system, and GeNN, a meta-compiler for parallel GPU hardware. We assess performance using a standard hand-written digit classification task. We found that whilst a different implementation approach was required for each platform, classification performances remained in line. This suggests that all three implementations were able to exercise the model's ability to solve the task rather than exposing inherent platform limits, although differences emerged when capacity was approached. With respect to execution speed and power consumption, we found that for each platform a large fraction of the computing time was spent outside of the neuromorphic device, on the host machine. Time was spent in a range of combinations of preparing the model, encoding suitable input spiking data, shifting data, and decoding spike-encoded results. This is also where a large proportion of the total power was consumed, most markedly for the SpiNNaker and Spikey systems. We conclude that the simulation efficiency advantage of the assessed specialized hardware systems is easily lost in excessive host-device communication, or non-neuronal parts of the computation. These results emphasize the need to optimize the host-device communication architecture for

  14. Comparing Neuromorphic Solutions in Action: Implementing a Bio-Inspired Solution to a Benchmark Classification Task on Three Parallel-Computing Platforms

    PubMed Central

    Diamond, Alan; Nowotny, Thomas; Schmuker, Michael

    2016-01-01

    Neuromorphic computing employs models of neuronal circuits to solve computing problems. Neuromorphic hardware systems are now becoming more widely available and “neuromorphic algorithms” are being developed. As they are maturing toward deployment in general research environments, it becomes important to assess and compare them in the context of the applications they are meant to solve. This should encompass not just task performance, but also ease of implementation, speed of processing, scalability, and power efficiency. Here, we report our practical experience of implementing a bio-inspired, spiking network for multivariate classification on three different platforms: the hybrid digital/analog Spikey system, the digital spike-based SpiNNaker system, and GeNN, a meta-compiler for parallel GPU hardware. We assess performance using a standard hand-written digit classification task. We found that whilst a different implementation approach was required for each platform, classification performances remained in line. This suggests that all three implementations were able to exercise the model's ability to solve the task rather than exposing inherent platform limits, although differences emerged when capacity was approached. With respect to execution speed and power consumption, we found that for each platform a large fraction of the computing time was spent outside of the neuromorphic device, on the host machine. Time was spent in a range of combinations of preparing the model, encoding suitable input spiking data, shifting data, and decoding spike-encoded results. This is also where a large proportion of the total power was consumed, most markedly for the SpiNNaker and Spikey systems. We conclude that the simulation efficiency advantage of the assessed specialized hardware systems is easily lost in excessive host-device communication, or non-neuronal parts of the computation. These results emphasize the need to optimize the host-device communication architecture

  15. Electrochemical properties of large-sized pouch-type lithium ion batteries with bio-inspired organic cathode materials

    NASA Astrophysics Data System (ADS)

    Yeo, Jae-Seong; Yoo, Eun-Ji; Ha, Sang-Hyeon; Cheong, Dong-Ik; Cho, Sung-Baek

    2016-05-01

    To investigate the feasibility of scaling up bio-inspired organic materials as cathode materials in lithium ion batteries, large-sized pouch cells are successfully prepared via tape casting using lumichrome with an alloxazine structure and aqueous styrene butadiene rubber-carboxymethyl cellulose (SBR-CMC) binders. A battery module with a two-in-series, six-in-parallel (2S6P) configuration is also successfully fabricated and is able to power blue LEDs (850 mW). Lumichrome shows no structural changes during the fabrication processes used to produce the positive electrode. The large-sized pouch cells show two sets of cathodic and anodic peaks with average potentials of 2.58 V and 2.26 V vs. Li/Li+, respectively. The initial discharge capacities are 142 mAh g-1 and 148 mAh g-1 for ethylene carbonate-dimethyl carbonate (EC-DMC) and tetraethylene glycol dimethyl ether (TEGDME) electrolytes, respectively, similar to that of a coin cell (149 mAh g-1). The EC-DMC-injected pouch cells exhibit higher rate performance and cyclability than the TEGDME-injected ones. The TEGDME electrolyte is not suitable for lithium metal anodes because of electrolyte decomposition and subsequent cell swelling.

  16. Bio-inspired Plasmonic Nanoarchitectured Hybrid System Towards Enhanced Far Red-to-Near Infrared Solar Photocatalysis

    NASA Astrophysics Data System (ADS)

    Yan, Runyu; Chen, Min; Zhou, Han; Liu, Tian; Tang, Xingwei; Zhang, Ke; Zhu, Hanxing; Ye, Jinhua; Zhang, Di; Fan, Tongxiang

    2016-01-01

    Solar conversion to fuels or to electricity in semiconductors using far red-to-near infrared (NIR) light, which accounts for about 40% of solar energy, is highly significant. One main challenge is the development of novel strategies for activity promotion and new basic mechanisms for NIR response. Mother Nature has evolved to smartly capture far red-to-NIR light via their intelligent systems due to unique micro/nanoarchitectures, thus motivating us for biomimetic design. Here we report the first demonstration of a new strategy, based on adopting nature’s far red-to-NIR responsive architectures for an efficient bio-inspired photocatalytic system. The system is constructed by controlled assembly of light-harvesting plasmonic nanoantennas onto a typical photocatalytic unit with butterfly wings’ 3D micro/nanoarchitectures. Experiments and finite-difference time-domain (FDTD) simulations demonstrate the structural effects on obvious far red-to-NIR photocatalysis enhancement, which originates from (1) Enhancing far red-to-NIR (700~1200 nm) harvesting, up to 25%. (2) Enhancing electric-field amplitude of localized surface plasmon (LSPs) to more than 3.5 times than that of the non-structured one, which promotes the rate of electron-hole pair formation, thus substantially reinforcing photocatalysis. This proof-of-concept study provides a new methodology for NIR photocatalysis and would potentially guide future conceptually new NIR responsive system designs.

  17. Bio-inspired fabrication of hierarchical Ni-Fe-P coated skin collagen fibers for high-performance microwave absorption.

    PubMed

    Wang, Xiaoling; Liao, Xuepin; Zhang, Wenhua; Shi, Bi

    2015-01-21

    In the present investigation, skin collagen fiber (CF) with a well defined hierarchical 3D fibrous structure was employed for the bio-inspired fabrication of high-performance microwave absorption materials. The hierarchical 3D structure of the CF was retained in the CF@Ni-Fe-P composites, and the formation of the Ni-Fe-P coating on the CF surface was identified by XRD and XPS analysis. Based on the electromagnetism parameter measurements, the maximum reflection loss (RL) of the CF@Ni-Fe-P composites reached -31.0 dB, and the width of the absorption band where reflection loss values exceeded -10.0 dB covered the whole Ku-band and some parts of the X-band (9.5-18.0 GHz). The complex permittivity and complex permeability measurements indicated that electronic loss and magnetic loss were involved in the CF@Ni-Fe-P composites for microwave absorption. In addition, due to the magnetic properties of the Ni-Fe-P coating, these CF@Ni-Fe-P composites exhibited excellent magnetic characteristics with high saturation magnetization and low coercivity values. The present investigation indicates a new possibility for the bio-matrix-based fabrication of high-performance microwave absorbing materials with lightweight and efficient absorption properties. PMID:25484199

  18. A Benchtop Closed-loop System Controlled by a Bio-Inspired Silicon Implementation of the Pancreatic β Cell

    PubMed Central

    Oliver, Nick; Georgiou, Pantelis; Johnston, Desmond; Toumazou, Christofer

    2009-01-01

    The normal pancreatic β-cell membrane depolarizes in response to increasing concentrations of glucose in a bursting pattern. At <7 mM (126 mg/dl), the cell is electrically silent. The bursting pulse width increases as glucose rises >7 mM (126 mg/dl) until a continuous train of bursting is seen at >25 mM (450 mg/dl). A bio-inspired silicon device has been developed using analogue electronics to implement membrane depolarization of the β cell. The device is ultralow powered, miniaturized (5 × 5 mm), and produces a bursting output identical to that characterized in electrophysiological studies. Objective The goal of this study was to demonstrate the ability of silicon implementation of β-cell electrophysiology to respond to a simulated glucose input and to drive an infusion pump in vitro. Method The silicon device response to a current source was recorded at varying simulated glucose concentrations. Subsequently, the bursting response to a changing analyte concentration measured by an amperometric enzyme electrode was converted to a voltage, driving a syringe pump loaded with a 50-ml syringe containing water. Results Bursting responses are comparable to those recorded in electrophysiology. Silicon β-cell implementation bursts with a pulse width proportional to concentration and is able to drive an infusion pump. Conclusion This is the first in vitro demonstration of closed loop insulin delivery utilizing miniaturized silicon implementation of β-cell physiology in analogue electronics. PMID:20144397

  19. The Tipping Point of Robotic Surgery In Healthcare: From Master-Slave to Flexible Access Bio-Inspired Platforms.

    PubMed

    Athanasiou, Thanos; Ashrafian, Hutan; Rao, Christopher; Yang, Guang-Zhong; Darzi, Ara

    2011-12-01

    Surgical robots were introduced to overcome the technical issues of limited operative dexterity and inadequate visualization in complex body areas. Current surgical robotic systems are based on a master-slave relationship in which the master-surgeon provides operative guidance for the slave-robot to perform operative tasks. Robotic operations are most frequently applied in urology (primarily focusing on prostatectomy) and cardiac surgery. The evolution of surgical robotics has made significant strides in the past decade. There are, however, some limitatio0The future of robotic surgery promises several augmentations to provide improvements in surgical visualization, somatosensory perception, and enhanced robot-surgeon interactions. These can be achieved through advances in robotic research and academic healthcare leadership to develop the next generation of surgical robots such as the novel flexible access bio-inspired (FAB) platforms. The drive to move toward ever less-invasive and safer procedures while maintaining high-quality treatment outcomes has maintained the momentum of progress since the initial birth of minimally invasive surgery, so that robotic surgery can be increasingly applied in a wider range of healthcare settings. PMID:22504967

  20. Synthesis and characterizations of hierarchical biomorphic titania oxide by a bio-inspired bottom-up assembly solution technique

    SciTech Connect

    Dong Qun; Su Huilan Cao Wei; Zhang Di; Guo Qixin; Lai Yijian

    2007-03-15

    As a representative semiconductor metal oxide, hierarchical biomorphic mesoporous TiO{sub 2} with interwoven meshwork conformation was successfully prepared using eggshell membrane (ESM) as a biotemplate by an aqueous soakage technique followed by calcination treatment. The synthesis conditions were systematically investigated by controlling the concentration, the pH value of the precursor impregnant, and so on. The nucleation, growth, and assembly into ESM-biomorphic TiO{sub 2} in our work depended more on the functions of ESM biomacromolecules as well as the processing conditions. As-prepared TiO{sub 2} meshwork exhibiting hierarchical porous structure with the pore size from 2 nm up to 4 {mu}m, was composed of intersectant fibers assembled by nanocrystallites at three dimensions. Based on the researches into the N{sub 2} adsorption-desorption isothermal and corresponding BJH pore-size distribution, the biomorphic TiO{sub 2} would arose interesting applications in some fields such as photocatalysis, gas sensors, antistatic coating, dye-sensitized solar cells, etc. This mild method and the relevant ideas offer a feasible path to synthesize a new family of functional materials by integrating material science, chemistry, and biotechnology. - Graphical abstract: Hierarchical mesoporous TiO{sub 2} is assembled by nanoparticles from the nanoscale to the macroscale through a bio-inspired sol-gel approach with eggshell membrane used as the biotemplate. As-prepared hierarchical titania shows porous characters within the pore size range of 2 nm-4 {mu}m.

  1. Bio-inspired green synthesis of Fe3O4 magnetic nanoparticles using watermelon rinds and their catalytic activity

    NASA Astrophysics Data System (ADS)

    Prasad, Ch.; Gangadhara, S.; Venkateswarlu, P.

    2016-08-01

    Novel and bio-inspired magnetic nanoparticles were synthesized using watermelon rinds (WR) which are nontoxic and biodegradable. Watermelon rind extract was used as a solvent and capping and reducing agent in the synthesis. The Fe3o4 MNPs were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer techniques (VSM). XRD studies revealed a high degree of crystalline and monophasic Fe nanoparticles of face-centered cubic stricture. FTIR analysis proved that particles are reduced and stabilized in solution by the capping agent that is likely to be proteins secreted by the biomass. The present process in an excellent candidate for the synthesis of iron nanoparticles that is simple, easy to execute, pollutant free and inexpensive. A practical and convenient method for the synthesis of highly stable and small-sized iron nanoparticles with a narrow distribution from 2 to 20 nm is reported. Also, the MNPs present in higher saturation magnetization (Ms) of 14.2 emu/g demonstrate tremendous magnetic response behavior. However, the synthesized iron nanoparticles were used as a catalyst for the preparation of biologically interesting 2-oxo-1,2,3,4-tetrahydropyrimidine derivatives in high yields. These results exhibited that the synthesized Fe3O4 MNPs could be used as a catalyst in organic synthesis.

  2. Obstacle traversal and self-righting of bio-inspired robots reveal the physics of multi-modal locomotion

    NASA Astrophysics Data System (ADS)

    Li, Chen; Fearing, Ronald; Full, Robert

    Most animals move in nature in a variety of locomotor modes. For example, to traverse obstacles like dense vegetation, cockroaches can climb over, push across, reorient their bodies to maneuver through slits, or even transition among these modes forming diverse locomotor pathways; if flipped over, they can also self-right using wings or legs to generate body pitch or roll. By contrast, most locomotion studies have focused on a single mode such as running, walking, or jumping, and robots are still far from capable of life-like, robust, multi-modal locomotion in the real world. Here, we present two recent studies using bio-inspired robots, together with new locomotion energy landscapes derived from locomotor-environment interaction physics, to begin to understand the physics of multi-modal locomotion. (1) Our experiment of a cockroach-inspired legged robot traversing grass-like beam obstacles reveals that, with a terradynamically ``streamlined'' rounded body like that of the insect, robot traversal becomes more probable by accessing locomotor pathways that overcome lower potential energy barriers. (2) Our experiment of a cockroach-inspired self-righting robot further suggests that body vibrations are crucial for exploring locomotion energy landscapes and reaching lower barrier pathways. Finally, we posit that our new framework of locomotion energy landscapes holds promise to better understand and predict multi-modal biological and robotic movement.

  3. Controlled RAFT Polymerization of 2-Vinyl-4,4-Dimethylazlactone (VDMA): A Facile Route to Bio-Inspired Polymer Surfaces

    SciTech Connect

    Lokitz, Bradley S; Messman, Jamie M; Hinestrosa Salazar, Juan Pablo; Alonzo Calderon, Jose E; Verduzco, Rafael; Brown, Rebecca H; Osa, Masashi; Ankner, John Francis; Kilbey, II, S Michael

    2009-01-01

    We report the controlled radical polymerization of 2-vinyl-4,4-dimethyl azlactone (VDMA), a 2-alkenyl-2-oxazolin-5-one monomer that contains a polymerizable vinyl moiety as well as a highly reactive, pendant azlactone as well as solution characterizations and surface attachment and functionaliztion. Reversible addition fragmentation chain transfer (RAFT) was used to polymerize of VDMA in benzene at 65 C using either 2-(2-cyanopropyl) dithiobenzoate (CPDB) or 2-dodecylsulfanylthiocarbonyl-sulfanyl-2-methylpropionic acid (DMP) as RAFT chain transfer agents (CTAs). The pseudo first order kinetics and resultant well-defined polymers of low polydispersity indicate that both CTAs afford control over the RAFT polymerization of VDMA. Dynamic and static light scattering and small angle neutron scattering were performed to determine the dn/dc, weight-average molecular weight, radius of gyration, and second virial coefficient of VDMA homopolymers in THF. Additionally, well-defined polymers of VDMA containing carboxyl end groups were covalently attached to epoxy modified silicon wafers via esterification to produce polymeric scaffolds that could be subsequently functionalized for various bio-inspired applications.

  4. Bio-inspired Plasmonic Nanoarchitectured Hybrid System Towards Enhanced Far Red-to-Near Infrared Solar Photocatalysis.

    PubMed

    Yan, Runyu; Chen, Min; Zhou, Han; Liu, Tian; Tang, Xingwei; Zhang, Ke; Zhu, Hanxing; Ye, Jinhua; Zhang, Di; Fan, Tongxiang

    2016-01-01

    Solar conversion to fuels or to electricity in semiconductors using far red-to-near infrared (NIR) light, which accounts for about 40% of solar energy, is highly significant. One main challenge is the development of novel strategies for activity promotion and new basic mechanisms for NIR response. Mother Nature has evolved to smartly capture far red-to-NIR light via their intelligent systems due to unique micro/nanoarchitectures, thus motivating us for biomimetic design. Here we report the first demonstration of a new strategy, based on adopting nature's far red-to-NIR responsive architectures for an efficient bio-inspired photocatalytic system. The system is constructed by controlled assembly of light-harvesting plasmonic nanoantennas onto a typical photocatalytic unit with butterfly wings' 3D micro/nanoarchitectures. Experiments and finite-difference time-domain (FDTD) simulations demonstrate the structural effects on obvious far red-to-NIR photocatalysis enhancement, which originates from (1) Enhancing far red-to-NIR (700~1200 nm) harvesting, up to 25%. (2) Enhancing electric-field amplitude of localized surface plasmon (LSPs) to more than 3.5 times than that of the non-structured one, which promotes the rate of electron-hole pair formation, thus substantially reinforcing photocatalysis. This proof-of-concept study provides a new methodology for NIR photocatalysis and would potentially guide future conceptually new NIR responsive system designs. PMID:26818680

  5. Improvement of water-repellent and hydrodynamic drag reduction properties on bio-inspired surface and exploring sharkskin effect mechanism

    NASA Astrophysics Data System (ADS)

    Luo, Yuehao; Liu, Yufei; Anderson, James; Li, Xiang; Li, Yuanyue

    2015-07-01

    Bio-inspired/biomimetic surface technologies focusing on sharkskin, lotus leaf, gecko feet, and others have attracted so lots of attentions from all over the world; meanwhile, they have also brought great advantages and profits for mankind. Sharkskin drag-reducing/low-resistance surface is the imperative consequence of nature selection and self-evolution in the long history, which can enable itself accommodate the living environments perfectly. Generally speaking, sharkskin effect can become transparent only in some certain velocity scope. How to expand its application range and enhance the drag reduction function further has developed into the urgent issue. In this article, the water-repellent and hydrodynamic drag-reducing effects are improved by adjusting sharkskin texture. The experimental results show that contact angle of more than 150° is achieved, and drag-reducing property is improved to some extent. In addition, the drag-reducing mechanism is explored and generalized from different aspects adopting the numerical simulation, which has important significance to comprehend sharkskin effect.

  6. Bio-inspired micro-nano structured surface with structural color and anisotropic wettability on Cu substrate

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Li, Shuyi; Niu, Shichao; Cao, Xiaowen; Han, Zhiwu; Ren, Luquan

    2016-08-01

    Inspired by the unique creatures in the nature, the femtosecond laser technology has been usually used to fabricate the periodic microstructures due to its advantages of rapidness, simplicity, ease of large-area fabrication, and simultaneously offering dual micro/nano-scale structures simply via one-step process for a wide variety of materials. By changing the experimental conditions, multi-functional surfaces which possess superhydrophobicity and structural colors could be achieved on copper substrate. In addition, the apparent contact angle can reach 144.3° without any further modification, which also exhibits the anisotropic wettability. Moreover, it can be inferred that higher laser fluence can lead to a larger CA within a certain range. At the same time, due to the change of laser processing parameters, the obtained surfaces present different structural colors. This study may expand the applications of bio-inspired functional materials because multiple colors and hydrophobicity are both important features in the real life and industrial applications, such as display, decoration, and anti-counterfeiting technology etc.

  7. Coaxial electrospinning of WO3 nanotubes functionalized with bio-inspired Pd catalysts and their superior hydrogen sensing performance.

    PubMed

    Choi, Seon-Jin; Chattopadhyay, Saptarshi; Kim, Jae Jin; Kim, Sang-Joon; Tuller, Harry L; Rutledge, Gregory C; Kim, Il-Doo

    2016-04-28

    Macroporous WO3 nanotubes (NTs) functionalized with nanoscale catalysts were fabricated using coaxial electrospinning combined with sacrificial templating and protein-encapsulated catalysts. The macroporous thin-walled nanotubular structures were obtained by introducing colloidal polystyrene (PS) particles to a shell solution of W precursor and poly(vinylpyrrolidone). After coaxial electrospinning with a core liquid of mineral oil and subsequent calcination, open pores with an average diameter of 173 nm were formed on the surface of WO3 NTs due to decomposition of the PS colloids. In addition, catalytic Pd nanoparticles (NPs) were synthesized using bio-inspired protein cages, i.e., apoferritin, and uniformly dispersed within the shell solution and subsequently on the WO3 NTs. The resulting Pd functionalized macroporous WO3 NTs were demonstrated to be high performance hydrogen (H2) sensors. In particular, Pd-functionalized macroporous WO3 NTs exhibited a very high H2 response (Rair/Rgas) of 17.6 at 500 ppm with a short response time. Furthermore, the NTs were shown to be highly selective for H2 compared to other gases such as carbon monoxide (CO), ammonia (NH3), and methane (CH4). The results demonstrate a new synthetic method to prepare highly porous nanotubular structures with well-dispersed nanoscale catalysts, which can provide improved microstructures for chemical sensing. PMID:26691720

  8. Bio-inspired Plasmonic Nanoarchitectured Hybrid System Towards Enhanced Far Red-to-Near Infrared Solar Photocatalysis

    PubMed Central

    Yan, Runyu; Chen, Min; Zhou, Han; Liu, Tian; Tang, Xingwei; Zhang, Ke; Zhu, Hanxing; Ye, Jinhua; Zhang, Di; Fan, Tongxiang

    2016-01-01

    Solar conversion to fuels or to electricity in semiconductors using far red-to-near infrared (NIR) light, which accounts for about 40% of solar energy, is highly significant. One main challenge is the development of novel strategies for activity promotion and new basic mechanisms for NIR response. Mother Nature has evolved to smartly capture far red-to-NIR light via their intelligent systems due to unique micro/nanoarchitectures, thus motivating us for biomimetic design. Here we report the first demonstration of a new strategy, based on adopting nature’s far red-to-NIR responsive architectures for an efficient bio-inspired photocatalytic system. The system is constructed by controlled assembly of light-harvesting plasmonic nanoantennas onto a typical photocatalytic unit with butterfly wings’ 3D micro/nanoarchitectures. Experiments and finite-difference time-domain (FDTD) simulations demonstrate the structural effects on obvious far red-to-NIR photocatalysis enhancement, which originates from (1) Enhancing far red-to-NIR (700~1200 nm) harvesting, up to 25%. (2) Enhancing electric-field amplitude of localized surface plasmon (LSPs) to more than 3.5 times than that of the non-structured one, which promotes the rate of electron-hole pair formation, thus substantially reinforcing photocatalysis. This proof-of-concept study provides a new methodology for NIR photocatalysis and would potentially guide future conceptually new NIR responsive system designs. PMID:26818680

  9. Lightweight mechanical amplifiers for rolled dielectric elastomer actuators and their integration with bio-inspired wing flappers

    NASA Astrophysics Data System (ADS)

    Lau, Gih-Keong; Lim, Hoong-Ta; Teo, Jing-Ying; Chin, Yao-Wei

    2014-02-01

    Dielectric elastomer actuators (DEAs) are attractive for use in bio-inspired flapping-wing robots because they have high work density (specific energy) and can produce a large actuation strain. Although the active membrane of a dielectric elastomer is lightweight, the support structure that pre-tensions the elastomeric membrane is massive and it lowers the overall work density. If the DEA is to be used successfully to drive flapping-wing robots, its support structure must be as lightweight as possible. In this work, we designed, analysed, and developed a lightweight shell using a cross-ply laminate of carbon fibre reinforced polymer (CFRP) to pre-strain a rolled DEA. The CFRP shell was shown to weigh 24.3% of the total mass for the whole DEA assembly, while providing up to 35.0% axial pre-strain to a rolled DEA (BJB-5005 silicone rubber). This DEA assembly using the CFRP shell achieved 30.9% of the theoretical work density for a BJB-TC5005 membrane at 33.5 MV m-1. In comparison, spring rolls with a massive spring core were reported with overall work density merely 10-20% of the maximum value. Furthermore, this CFRP shell can amplify an axial DEA stroke into a larger transverse shell deformation. With these deformation characteristics, this CFRP shell and a rolled DEA were successfully integrated with an insect-inspired thoracic mechanism and they were shown to be feasible to drive it for a flapping wing.

  10. Tension-induced tunable corrugation in bio-inspired two-phase soft composite materials: mechanisms and implications

    NASA Astrophysics Data System (ADS)

    Elbanna, Ahmed; Chen, Qianli

    We numerically investigate the elastic deformation response of a two-phase bio-inspired soft composite material under externally applied concentric tension using the finite element method. We show that by carefully designing the inclusion pattern it is possible to induce corrugations normal to the direction of stretch. By stacking 1D composite fibers to form 2D membranes, these corrugations collectively lead to the formation of membrane channels with shapes and sizes that are tunable by the level of stretch. Furthermore, we show that by using specific inclusion patterns in laminated plates, it is possible to create pop-ups and troughs enabling the development of complex 3D geometries from planar construction. We have found that the corrugation amplitude increases with the stiffness of inclusion and its eccentricity from the tension axis. We discuss the mechanisms leading to the development of corrugations as well as its different implications. We discuss applications for this design in a variety of fields including tunable band gap formation, surface roughness controllability, auxetic materials and toughness enhancement via programmable evolving geometrical effects..

  11. Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

    NASA Astrophysics Data System (ADS)

    Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

    2014-07-01

    The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human-robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as αf + ξf and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, αf + ξf has a non-linear dependence on temperature and varies from 6.0 × 10-6 °C-1 (20 °C) to 10.6 × 10-6 °C-1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C.

  12. A Bio-Inspired, Heavy-Metal-Free, Dual-Electrolyte Liquid Battery towards Sustainable Energy Storage.

    PubMed

    Ding, Yu; Yu, Guihua

    2016-04-01

    Wide-scale exploitation of renewable energy requires low-cost efficient energy storage devices. The use of metal-free, inexpensive redox-active organic materials represents a promising direction for environmental-friendly, cost-effective sustainable energy storage. To this end, a liquid battery is designed using hydroquinone (H2 BQ) aqueous solution as catholyte and graphite in aprotic electrolyte as anode. The working potential can reach 3.4 V, with specific capacity of 395 mA h g(-1) and stable capacity retention about 99.7 % per cycle. Such high potential and capacity is achieved using only C, H and O atoms as building blocks for redox species, and the replacement of Li metal with graphite anode can circumvent potential safety issues. As H2 BQ can be extracted from biomass directly and its redox reaction mimics the bio-electrochemical process of quinones in nature, using such a bio-inspired organic compound in batteries enables access to greener and more sustainable energy-storage technology. PMID:26958787

  13. Toward a three-dimensional viscous vortex particle method for numerical investigations of bio-inspired locomotion

    NASA Astrophysics Data System (ADS)

    Eldredge, Jeff

    2008-11-01

    Biological mechanics of aerial and aquatic locomotion are characterized by the reaction force generated by the fluid against highly deforming structures and the resultant vortical wake produced by this interaction. These two features should be central to a high-fidelity computational tool devoted to exploration of bio-inspired mechanics. Motivated by such problems, we present the development of a viscous vortex particle method with coupled body dynamics. The previously developed and validated tool for two-dimensional problems is briefly reviewed. The interaction between vorticity generation, reaction force, and body dynamics, which constitutes the fluid-structure coupling in the method, is discussed, and the capabilities of the method are demonstrated on the passive propulsion of a fish-like system in the wake of an obstacle. The method is extended to three-dimensional problems, and the various components of the solver are highlighted. The core routines of the three-dimensional tool make use of the Parallel Particle-Mesh library, developed by Koumoutsakos and co-workers (J. Comput. Phys., 215, 2006). The new method is demonstrated with preliminary results of a simple model for a dolphin tail with flexible flukes.

  14. Bio-inspired turbine blades offer new perspectives for wind energy

    NASA Astrophysics Data System (ADS)

    Thiria, Benjamin; Cognet, Vincent; Courrech Du Pont, Sylvain; PMMH Team; MSC Team

    2014-11-01

    The efficiency of wind turbines is especially poor if the wind speed is too low for the working range of the rotor, or if the oncoming wind has a too large incident angle with respect to the rotor axis. The consequence is that a large amount of potential available wind energy is not converted by the turbines, leading to heavy energetic and economic losses. The present work introduces a solution to overcome this technological limitation, using new types of blades connected to the rotors. This new type of blades is inspired by recent studies showing how insects improve flight performance by taking benefit from the flexibility of their wings (Ramananarivo et al. PNAS, 2011). Here, we show that, by bending along the chord under the action of the wind, the deformable blade plays the role of a shape factor to reorientate the torque in the direction of the rotation of the rotor, an especially helpful feature for critical wind conditions. The flexibility of the wing can significantly extend the performance range of wind turbines to low wind speeds and high azimuthal incoming wind directions, solving the technological barrier specific to this type of machines. The consequences of the presented results are outstanding for renewable solutions. Our estimation based on real wind data predicts a large increase in energy production, which is drawn using passive, non-consuming mechanisms, from the reservoir of energy available at critical wind conditions.

  15. A bio-inspired infrared imager with on chip object computation

    NASA Astrophysics Data System (ADS)

    McCarley, Paul L.; Caulfield, John T.

    2014-06-01

    This paper discusses a Biologically Inspired Shortwave Infrared (SWIR) imager that performs on chip object detection using temporal and spatial processing embedded in the imager's readout integrated circuit (ROIC). The sensor circuit is designed to detect pixel level intensity changes and correlate the change with nearby intensity changes using multiple thresholding criteria to output object exceedances. The sensor is capable of automatically outputting both normal video and also a reduced data set of binarized exceedances. Therefore this SWIR sensor with onboard temporal spatial sensing should be well suited to both manned and unmanned sensing scenarios which could benefit from automated object detection and reduced data sets.

  16. Bio-inspired flexible joints with passive feathering for robotic fish pectoral fins.

    PubMed

    Behbahani, Sanaz Bazaz; Tan, Xiaobo

    2016-06-01

    In this paper a novel flexible joint is proposed for robotic fish pectoral fins, which enables a swimming behavior emulating the fin motions of many aquatic animals. In particular, the pectoral fin operates primarily in the rowing mode, while undergoing passive feathering during the recovery stroke to reduce hydrodynamic drag on the fin. The latter enables effective locomotion even with symmetric base actuation during power and recovery strokes. A dynamic model is developed to facilitate the understanding and design of the joint, where blade element theory is used to calculate the hydrodynamic forces on the pectoral fins, and the joint is modeled as a paired torsion spring and damper. Experimental results on a robotic fish prototype are presented to illustrate the effectiveness of the joint mechanism, validate the proposed model, and indicate the utility of the proposed model for the optimal design of joint depth and stiffness in achieving the trade-off between swimming speed and mechanical efficiency. PMID:27144946

  17. Self-propelled swimming simulations of bio-inspired smart structures.

    PubMed

    Daghooghi, Mohsen; Borazjani, Iman

    2016-01-01

    This paper presents self-propelled swimming simulations of a foldable structure, whose folded configuration is a box. For self-locomotion through water the structure unfolds and undulates. To guide the design of the structure and understand how it should undulate to achieve either highest speed or maximize efficiency during locomotion, several kinematic parameters were systematically varied in the simulations: the wave type (standing wave versus traveling wave), the smoothness of undulations (smooth undulations versus undulations of rigid links), the mode of undulations (carangiform: mackerel-like versus anguilliform: eel-like undulations), and the maximum amplitude of undulations. We show that the swimmers with standing wave are slow and inefficient because they are not able to produce thrust using the added-mass mechanism. Among the tested types of undulation at low Reynolds number (Re) regime of [Formula: see text] (Strouhal number of about 1.0), structures that employ carangiform undulations can swim faster, whereas anguilliform swimmers are more economic, i.e., using less power they can swim a longer distance. Another finding of our simulations is that structures which are made of rigid links are typically less efficient (lower propulsive and power efficiencies and also lower swimming speed) compared with smoothly undulating ones because a higher added-mass force is generated by smooth undulations. The wake of all the swimmers bifurcated at the low Re regime because of the higher lateral relative to the axial velocity (high Strouhal number) that advects the vortices laterally creating a double row of vortices in the wake. In addition, we show that the wake cannot be used to predict the performance of the swimmers because the net force in each cycle is zero for self-propelled bodies and the pressure term is not negligible compared to the other terms. PMID:27501748

  18. Time-recovering PCI-AER interface for bio-inspired spiking systems

    NASA Astrophysics Data System (ADS)

    Paz-Vicente, R.; Linares-Barranco, A.; Cascado, D.; Vicente, S.; Jimenez, G.; Civit, A.

    2005-06-01

    Address Event Representation (AER) is an emergent neuromorphic interchip communication protocol that allows for real-time virtual massive connectivity between huge number neurons located on different chips. By exploiting high speed digital communication circuits (with nano-seconds timings), synaptic neural connections can be time multiplexed, while neural activity signals (with mili-seconds timings) are sampled at low frequencies. Also, neurons generate 'events' according to their activity levels. More active neurons generate more events per unit time, and access the interchip communication channel more frequently, while neurons with low activity consume less communication bandwidth. When building multi-chip muti-layered AER systems it is absolutely necessary to have a computer interface that allows (a) to read AER interchip traffic into the computer and visualize it on screen, and (b) inject a sequence of events at some point of the AER structure. This is necessary for testing and debugging complex AER systems. This paper presents a PCI to AER interface, that dispatches a sequence of events received from the PCI bus with embedded timing information to establish when each event will be delivered. A set of specialized states machines has been introduced to recovery the possible time delays introduced by the asynchronous AER bus. On the input channel, the interface capture events assigning a timestamp and delivers them through the PCI bus to MATLAB applications. It has been implemented in real time hardware using VHDL and it has been tested in a PCI-AER board, developed by authors, that includes a Spartan II 200 FPGA. The demonstration hardware is currently capable to send and receive events at a peak rate of 8,3 Mev/sec, and a typical rate of 1 Mev/sec.

  19. Bio-inspired digital signal processing for fast radionuclide mixture identification

    NASA Astrophysics Data System (ADS)

    Thevenin, M.; Bichler, O.; Thiam, C.; Bobin, C.; Lourenço, V.

    2015-05-01

    Countries are trying to equip their public transportation infrastructure with fixed radiation portals and detectors to detect radiological threat. Current works usually focus on neutron detection, which could be useless in the case of dirty bomb that would not use fissile material. Another approach, such as gamma dose rate variation monitoring is a good indication of the presence of radionuclide. However, some legitimate products emit large quantities of natural gamma rays; environment also emits gamma rays naturally. They can lead to false detections. Moreover, such radio-activity could be used to hide a threat such as material to make a dirty bomb. Consequently, radionuclide identification is a requirement and is traditionally performed by gamma spectrometry using unique spectral signature of each radionuclide. These approaches require high-resolution detectors, sufficient integration time to get enough statistics and large computing capacities for data analysis. High-resolution detectors are fragile and costly, making them bad candidates for large scale homeland security applications. Plastic scintillator and NaI detectors fit with such applications but their resolution makes identification difficult, especially radionuclides mixes. This paper proposes an original signal processing strategy based on artificial spiking neural networks to enable fast radionuclide identification at low count rate and for mixture. It presents results obtained for different challenging mixtures of radionuclides using a NaI scintillator. Results show that a correct identification is performed with less than hundred counts and no false identification is reported, enabling quick identification of a moving threat in a public transportation. Further work will focus on using plastic scintillators.

  20. A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

    SciTech Connect

    Romeo, Agostino; Dimonte, Alice; Tarabella, Giuseppe; D’Angelo, Pasquale E-mail: iannotta@imem.cnr.it; Erokhin, Victor; Iannotta, Salvatore E-mail: iannotta@imem.cnr.it

    2015-01-01

    The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC) slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

  1. Coaxial electrospinning of WO3 nanotubes functionalized with bio-inspired Pd catalysts and their superior hydrogen sensing performance

    NASA Astrophysics Data System (ADS)

    Choi, Seon-Jin; Chattopadhyay, Saptarshi; Kim, Jae Jin; Kim, Sang-Joon; Tuller, Harry L.; Rutledge, Gregory C.; Kim, Il-Doo

    2016-04-01

    Macroporous WO3 nanotubes (NTs) functionalized with nanoscale catalysts were fabricated using coaxial electrospinning combined with sacrificial templating and protein-encapsulated catalysts. The macroporous thin-walled nanotubular structures were obtained by introducing colloidal polystyrene (PS) particles to a shell solution of W precursor and poly(vinylpyrrolidone). After coaxial electrospinning with a core liquid of mineral oil and subsequent calcination, open pores with an average diameter of 173 nm were formed on the surface of WO3 NTs due to decomposition of the PS colloids. In addition, catalytic Pd nanoparticles (NPs) were synthesized using bio-inspired protein cages, i.e., apoferritin, and uniformly dispersed within the shell solution and subsequently on the WO3 NTs. The resulting Pd functionalized macroporous WO3 NTs were demonstrated to be high performance hydrogen (H2) sensors. In particular, Pd-functionalized macroporous WO3 NTs exhibited a very high H2 response (Rair/Rgas) of 17.6 at 500 ppm with a short response time. Furthermore, the NTs were shown to be highly selective for H2 compared to other gases such as carbon monoxide (CO), ammonia (NH3), and methane (CH4). The results demonstrate a new synthetic method to prepare highly porous nanotubular structures with well-dispersed nanoscale catalysts, which can provide improved microstructures for chemical sensing.Macroporous WO3 nanotubes (NTs) functionalized with nanoscale catalysts were fabricated using coaxial electrospinning combined with sacrificial templating and protein-encapsulated catalysts. The macroporous thin-walled nanotubular structures were obtained by introducing colloidal polystyrene (PS) particles to a shell solution of W precursor and poly(vinylpyrrolidone). After coaxial electrospinning with a core liquid of mineral oil and subsequent calcination, open pores with an average diameter of 173 nm were formed on the surface of WO3 NTs due to decomposition of the PS colloids. In addition

  2. Mobile robots for localizing gas emission sources on landfill sites: is bio-inspiration the way to go?

    PubMed

    Hernandez Bennetts, Victor; Lilienthal, Achim J; Neumann, Patrick P; Trincavelli, Marco

    2011-01-01

    Roboticists often take inspiration from animals for designing sensors, actuators, or algorithms that control the behavior of robots. Bio-inspiration is motivated with the uncanny ability of animals to solve complex tasks like recognizing and manipulating objects, walking on uneven terrains, or navigating to the source of an odor plume. In particular the task of tracking an odor plume up to its source has nearly exclusively been addressed using biologically inspired algorithms and robots have been developed, for example, to mimic the behavior of moths, dung beetles, or lobsters. In this paper we argue that biomimetic approaches to gas source localization are of limited use, primarily because animals differ fundamentally in their sensing and actuation capabilities from state-of-the-art gas-sensitive mobile robots. To support our claim, we compare actuation and chemical sensing available to mobile robots to the corresponding capabilities of moths. We further characterize airflow and chemosensor measurements obtained with three different robot platforms (two wheeled robots and one flying micro-drone) in four prototypical environments and show that the assumption of a constant and unidirectional airflow, which is the basis of many gas source localization approaches, is usually far from being valid. This analysis should help to identify how underlying principles, which govern the gas source tracking behavior of animals, can be usefully "translated" into gas source localization approaches that fully take into account the capabilities of mobile robots. We also describe the requirements for a reference application, monitoring of gas emissions at landfill sites with mobile robots, and discuss an engineered gas source localization approach based on statistics as an alternative to biologically inspired algorithms. PMID:22319493

  3. Bio-inspired hybrid microelectrodes: a hybrid solution to improve long-term performance of chronic intracortical implants

    PubMed Central

    De Faveri, Sara; Maggiolini, Emma; Miele, Ermanno; De Angelis, Francesco; Cesca, Fabrizia; Benfenati, Fabio; Fadiga, Luciano

    2014-01-01

    The use of implants that allow chronic electrical stimulation and recording in the brain of human patients is currently limited by a series of events that cause the deterioration over time of both the electrode surface and the surrounding tissue. The main reason of failure is the tissue inflammatory reaction that eventually causes neuronal loss and glial encapsulation, resulting in a progressive increase of the electrode-electrolyte impedance. Here, we describe a new method to create bio-inspired electrodes to mimic the mechanical properties and biological composition of the host tissue. This combination has a great potential to increase the implant lifetime by reducing tissue reaction and improving electrical coupling. Our method implies coating the electrode with reprogrammed neural or glial cells encapsulated within a hydrogel layer. We chose fibrin as a hydrogel and primary hippocampal neurons or astrocytes from rat brain as cellular layer. We demonstrate that fibrin coating is highly biocompatible, forms uniform coatings of controllable thickness, does not alter the electrochemical properties of the microelectrode and allows good quality recordings. Moreover, it reduces the amount of host reactive astrocytes – over time – compared to a bare wire and is fully reabsorbed by the surrounding tissue within 7 days after implantation, avoiding the common problem of hydrogels swelling. Both astrocytes and neurons could be successfully grown onto the electrode surface within the fibrin hydrogel without altering the electrochemical properties of the microelectrode. This bio-hybrid device has therefore a good potential to improve the electrical integration at the neuron-electrode interface and support the long-term success of neural prostheses. PMID:24782757

  4. Mobile Robots for Localizing Gas Emission Sources on Landfill Sites: Is Bio-Inspiration the Way to Go?

    PubMed Central

    Hernandez Bennetts, Victor; Lilienthal, Achim J.; Neumann, Patrick P.; Trincavelli, Marco

    2011-01-01

    Roboticists often take inspiration from animals for designing sensors, actuators, or algorithms that control the behavior of robots. Bio-inspiration is motivated with the uncanny ability of animals to solve complex tasks like recognizing and manipulating objects, walking on uneven terrains, or navigating to the source of an odor plume. In particular the task of tracking an odor plume up to its source has nearly exclusively been addressed using biologically inspired algorithms and robots have been developed, for example, to mimic the behavior of moths, dung beetles, or lobsters. In this paper we argue that biomimetic approaches to gas source localization are of limited use, primarily because animals differ fundamentally in their sensing and actuation capabilities from state-of-the-art gas-sensitive mobile robots. To support our claim, we compare actuation and chemical sensing available to mobile robots to the corresponding capabilities of moths. We further characterize airflow and chemosensor measurements obtained with three different robot platforms (two wheeled robots and one flying micro-drone) in four prototypical environments and show that the assumption of a constant and unidirectional airflow, which is the basis of many gas source localization approaches, is usually far from being valid. This analysis should help to identify how underlying principles, which govern the gas source tracking behavior of animals, can be usefully “translated” into gas source localization approaches that fully take into account the capabilities of mobile robots. We also describe the requirements for a reference application, monitoring of gas emissions at landfill sites with mobile robots, and discuss an engineered gas source localization approach based on statistics as an alternative to biologically inspired algorithms. PMID:22319493

  5. A Bio-inspired Collision Avoidance Model Based on Spatial Information Derived from Motion Detectors Leads to Common Routes

    PubMed Central

    Bertrand, Olivier J. N.; Lindemann, Jens P.; Egelhaaf, Martin

    2015-01-01

    Avoiding collisions is one of the most basic needs of any mobile agent, both biological and technical, when searching around or aiming toward a goal. We propose a model of collision avoidance inspired by behavioral experiments on insects and by properties of optic flow on a spherical eye experienced during translation, and test the interaction of this model with goal-driven behavior. Insects, such as flies and bees, actively separate the rotational and translational optic flow components via behavior, i.e. by employing a saccadic strategy of flight and gaze control. Optic flow experienced during translation, i.e. during intersaccadic phases, contains information on the depth-structure of the environment, but this information is entangled with that on self-motion. Here, we propose a simple model to extract the depth structure from translational optic flow by using local properties of a spherical eye. On this basis, a motion direction of the agent is computed that ensures collision avoidance. Flying insects are thought to measure optic flow by correlation-type elementary motion detectors. Their responses depend, in addition to velocity, on the texture and contrast of objects and, thus, do not measure the velocity of objects veridically. Therefore, we initially used geometrically determined optic flow as input to a collision avoidance algorithm to show that depth information inferred from optic flow is sufficient to account for collision avoidance under closed-loop conditions. Then, the collision avoidance algorithm was tested with bio-inspired correlation-type elementary motion detectors in its input. Even then, the algorithm led successfully to collision avoidance and, in addition, replicated the characteristics of collision avoidance behavior of insects. Finally, the collision avoidance algorithm was combined with a goal direction and tested in cluttered environments. The simulated agent then showed goal-directed behavior reminiscent of components of the navigation

  6. Real-time object tracking based on scale-invariant features employing bio-inspired hardware.

    PubMed

    Yasukawa, Shinsuke; Okuno, Hirotsugu; Ishii, Kazuo; Yagi, Tetsuya

    2016-09-01

    We developed a vision sensor system that performs a scale-invariant feature transform (SIFT) in real time. To apply the SIFT algorithm efficiently, we focus on a two-fold process performed by the visual system: whole-image parallel filtering and frequency-band parallel processing. The vision sensor system comprises an active pixel sensor, a metal-oxide semiconductor (MOS)-based resistive network, a field-programmable gate array (FPGA), and a digital computer. We employed the MOS-based resistive network for instantaneous spatial filtering and a configurable filter size. The FPGA is used to pipeline process the frequency-band signals. The proposed system was evaluated by tracking the feature points detected on an object in a video. PMID:27268260

  7. Bio-inspired sensorization of a biomechatronic robot hand for the grasp-and-lift task.

    PubMed

    Edin, B B; Ascari, L; Beccai, L; Roccella, S; Cabibihan, J-J; Carrozza, M C

    2008-04-15

    It has been concluded from numerous neurophysiological studies that humans rely on detecting discrete mechanical events that occur when grasping, lifting and replacing an object, i.e., during a prototypical manipulation task. Such events represent transitions between phases of the evolving manipulation task such as object contact, lift-off, etc., and appear to provide critical information required for the sequential control of the task as well as for corrections and parameterization of the task. We have sensorized a biomechatronic anthropomorphic hand with the goal to detect such mechanical transients. The developed sensors were designed to specifically provide the information about task-relevant discrete events rather than to mimic their biological counterparts. To accomplish this we have developed (1) a contact sensor that can be applied to the surface of the robotic fingers and that show a sensitivity to indentation and a spatial resolution comparable to that of the human glabrous skin, and (2) a sensitive low-noise three-axial force sensor that was embedded in the robotic fingertips and showed a frequency response covering the range observed in biological tactile sensors. We describe the design and fabrication of these sensors, their sensory properties and show representative recordings from the sensors during grasp-and-lift tasks. We show how the combined use of the two sensors is able to provide information about crucial mechanical events during such tasks. We discuss the importance of the sensorized hand as a test bed for low-level grasp controllers and for the development of functional sensory feedback from prosthetic devices. PMID:18394525

  8. BATMAV - A Bio-Inspired Micro-Aerial Vehicle for Flapping Flight

    NASA Astrophysics Data System (ADS)

    Bunget, Gheorghe

    The main objective of the BATMAV project is the development of a biologically-inspired Micro Aerial Vehicle (MAV) with flexible and foldable wings for flapping flight. While flapping flight in MAV has been previously studied and a number of models were realized they usually had unfoldable wings actuated with DC motors and mechanical transmission to achieve flapping motion. This approach limits the system to a rather small number of degrees of freedom with little flexibility and introduces an additional disadvantage of a heavy flight platform. The BATMAV project aims at the development of a flight platform that features bat-inspired wings with smart materials-based flexible joints and artificial muscles, which has the potential to closely mimic the kinematics of the real mammalian flyer. The bat-like flight platform was selected after an extensive analysis of morphological and aerodynamic flight parameters of small birds, bats and large insects characterized by a superior maneuverability and wind gust rejection. Morphological and aerodynamic parameters were collected from existing literature and compared concluding that bat wing present a suitable platform that can be actuated efficiently using artificial muscles. Due to their wing camber variation, the bat species can operate effectively at a large range of speeds and exhibit a remarkably maneuverable and agile flight. Although numerous studies were recently investigated the flapping flight, flexible and foldable wings that reproduce the natural intricate and efficient flapping motion were not designed yet. A comprehensive analysis of flight styles in bats based on the data collected by Norberg (Norberg, 1976) and the engineering theory of robotic manipulators resulted in a 2 and 3-DOF models which managed to mimic the wingbeat cycle of the natural flyer. The flexible joints of the 2 and 2-DOF models were replicated using smart materials like superelastic Shape Memory Alloys (SMA). The results of these kinematic

  9. Bio-Inspired Polarized Skylight-Based Navigation Sensors: A Review

    PubMed Central

    Karman, Salmah B.; Diah, S. Zaleha M.; Gebeshuber, Ille C.

    2012-01-01

    Animal senses cover a broad range of signal types and signal bandwidths and have inspired various sensors and bioinstrumentation devices for biological and medical applications. Insects, such as desert ants and honeybees, for example, utilize polarized skylight pattern-based information in their navigation activities. They reliably return to their nests and hives from places many kilometers away. The insect navigation system involves the dorsal rim area in their compound eyes and the corresponding polarization sensitive neurons in the brain. The dorsal rim area is equipped with photoreceptors, which have orthogonally arranged small hair-like structures termed microvilli. These are the specialized sensors for the detection of polarized skylight patterns (e-vector orientation). Various research groups have been working on the development of novel navigation systems inspired by polarized skylight-based navigation in animals. Their major contributions are critically reviewed. One focus of current research activities is on imitating the integration path mechanism in desert ants. The potential for simple, high performance miniaturized bioinstrumentation that can assist people in navigation will be explored. PMID:23202158

  10. Understanding Vesicles and Bio-Inspired Systems with Dissipative Particle Dynamics

    NASA Astrophysics Data System (ADS)

    Shillcock, Julian C.

    Biological organisms have always been a source of inspiration for the designers of artificial materials and machines. At the boundaries of Biology, Chemistry and Physics, this process of borrowing from Nature is becoming increasingly important for several reasons. Industrial sectors, such as pharmaceutical com- panies and the chemicals industry [1], are keen to understand and rationally modify the design of natural materials so as to minimise manufacturing costs and create new materials whose properties are better suited to their purpose. Biologists and biophysicists would like to understand how organisms perform crucial life functions, such as protecting themselves against infectious agents, so that they can mimic these functions in the fields of medical treatment and bioweapons detection. Novel treatments for genetic diseases require the con- trolled replacement of defective genes with healthy ones, and will only fulfill their promise if their delivery can be made routine and reliable. The construc- tion of artificial viruses [2] to deliver genetic material is a promising route, but understanding the interactions of their components, and optimising their structure, are challenging tasks.

  11. Bio-inspired polarized skylight-based navigation sensors: a review.

    PubMed

    Karman, Salmah B; Diah, S Zaleha M; Gebeshuber, Ille C

    2012-01-01

    Animal senses cover a broad range of signal types and signal bandwidths and have inspired various sensors and bioinstrumentation devices for biological and medical applications. Insects, such as desert ants and honeybees, for example, utilize polarized skylight pattern-based information in their navigation activities. They reliably return to their nests and hives from places many kilometers away. The insect navigation system involves the dorsal rim area in their compound eyes and the corresponding polarization sensitive neurons in the brain. The dorsal rim area is equipped with photoreceptors, which have orthogonally arranged small hair-like structures termed microvilli. These are the specialized sensors for the detection of polarized skylight patterns (e-vector orientation). Various research groups have been working on the development of novel navigation systems inspired by polarized skylight-based navigation in animals. Their major contributions are critically reviewed. One focus of current research activities is on imitating the integration path mechanism in desert ants. The potential for simple, high performance miniaturized bioinstrumentation that can assist people in navigation will be explored. PMID:23202158

  12. Macromodeling for analog design and robustness boosting in bio-inspired computing models

    NASA Astrophysics Data System (ADS)

    Cuadri, J.; Linan, G.; Roca, E.; Rodriguez-Vazquez, A.

    2005-06-01

    Setting specifications for the electronic implementation of biological neural-network-like vision systems on-chip is not straightforward, neither it is to simulate the resulting circuit. The structure of these systems leads to a netlist of more than 100.000 nodes for a small array of 100x150 pixels. Moreover, introducing an optical input in the low level simulation is nowadays not feasible with standard electrical simulation environments. Given that, to accomplish the task of integrating those systems in silicon to build compact, low power consuming, and reliable systems, a previous step in the standard analog electronic design flux should be introduced. Here a methodology to make the translation from the biological model to circuit-level specifications for electronic design is proposed. The purpose is to include non ideal effects as mismatching, noise, leakages, supply degradation, feedthrough, and temperature of operation in a high level description of the implementation, in order to accomplish behavioural simulations that require less computational effort and resources. A particular case study is presented, the analog electronic implementation of the locust"s Lobula Giant Movement Detector (LGMD), a neural structure that fires a collision alarm based on visual information. The final goal is a collision threat detection vision system on-chip for automotive applications.

  13. Bio-inspired multi-mode optic flow sensors for micro air vehicles

    NASA Astrophysics Data System (ADS)

    Park, Seokjun; Choi, Jaehyuk; Cho, Jihyun; Yoon, Euisik

    2013-06-01

    Monitoring wide-field surrounding information is essential for vision-based autonomous navigation in micro-air-vehicles (MAV). Our image-cube (iCube) module, which consists of multiple sensors that are facing different angles in 3-D space, can be applied to the wide-field of view optic flows estimation (μ-Compound eyes) and to attitude control (μ- Ocelli) in the Micro Autonomous Systems and Technology (MAST) platforms. In this paper, we report an analog/digital (A/D) mixed-mode optic-flow sensor, which generates both optic flows and normal images in different modes for μ- Compound eyes and μ-Ocelli applications. The sensor employs a time-stamp based optic flow algorithm which is modified from the conventional EMD (Elementary Motion Detector) algorithm to give an optimum partitioning of hardware blocks in analog and digital domains as well as adequate allocation of pixel-level, column-parallel, and chip-level signal processing. Temporal filtering, which may require huge hardware resources if implemented in digital domain, is remained in a pixel-level analog processing unit. The rest of the blocks, including feature detection and timestamp latching, are implemented using digital circuits in a column-parallel processing unit. Finally, time-stamp information is decoded into velocity from look-up tables, multiplications, and simple subtraction circuits in a chip-level processing unit, thus significantly reducing core digital processing power consumption. In the normal image mode, the sensor generates 8-b digital images using single slope ADCs in the column unit. In the optic flow mode, the sensor estimates 8-b 1-D optic flows from the integrated mixed-mode algorithm core and 2-D optic flows with an external timestamp processing, respectively.

  14. A Mechanism for Error Detection in Speeded Response Time Tasks

    ERIC Educational Resources Information Center

    Holroyd, Clay B.; Yeung, Nick; Coles, Michael G. H.; Cohen, Jonathan D.

    2005-01-01

    The concept of error detection plays a central role in theories of executive control. In this article, the authors present a mechanism that can rapidly detect errors in speeded response time tasks. This error monitor assigns values to the output of cognitive processes involved in stimulus categorization and response generation and detects errors…

  15. Star-shaped polymers of bio-inspired algae core and poly(acrylamide) and poly(acrylic acid) as arms in dissolution of silica/silicate.

    PubMed

    Chauhan, Kalpana; Patiyal, Priyanka; Chauhan, Ghanshyam S; Sharma, Praveen

    2014-06-01

    Silica, in natural waters (due to weathering of rocks) decreases system performance in water processing industry due to scaling. In view of that, the present work involves the synthesis of novel green star shaped additives of algae core (a bio-inspired material as diatom maintains silicic acid equilibrium in sea water) as silica polymerization inhibitors. Star shaped materials with bio-inspired core and poly(acrylamide) [poly(AAm)] and poly(acrylic acid) [poly(AAc)] arms were synthesized by economical green approach. The proficiency was evaluated in 'mini lab' scale for the synthesized APAAm (Algae-g-poly(AAm)) and APAAc (Algae-g-poly(AAc)) dendrimers (star shaped) in colloidal silica mitigation/inhibition at 35 °C and 55 °C. Synthesized dendrimers were equally proficient in silica inhibition at 12 h and maintains ≥450 ppm soluble silica. However, APAAm dendrimers of generation 0 confirmed better results (≈300 ppm) in contrast to APAAc dendrimers in silica inhibition at 55 °C. Additionally, dendrimers also worked as a nucleator for heterogeneous polymerization to inhibit silica homo-polymerization. APAAm dendrimer test set showed no silica deposit for more than 10 days of inhibition. EDX characterization results support nucleator mechanism with Si content of 6.97%-10.98% by weight in silica deposits (SiO2-APAAm dendrimer composites). PMID:24681378

  16. Effects of different crosslinking conditions on the chemical-physical properties of a novel bio-inspired composite scaffold stabilised with 1,4-butanediol diglycidyl ether (BDDGE).

    PubMed

    Nicoletti, A; Fiorini, M; Paolillo, J; Dolcini, L; Sandri, M; Pressato, D

    2013-01-01

    Serious cartilage lesions (Outerbridge III, IV) may be successfully treated with a three-layered gradient scaffold made by magnesium-doped hydroxyapatite and type I collagen, manufactured through a bio-inspired process and stabilised by a reactive bis-epoxy (1,4-butanediol diglycidyl ether, BDDGE). Each layer was analysed to elucidate the effects of crosslinking variables (concentration, temperature and pH). The chemical stabilisation led to an homogeneous and aligned collagenous matrix: the fibrous structures switched to a laminar foils-based arrangement and organic phases acquired an highly coordinated 3D-organization. These morphological features were strongly evident when crosslinking occurred in alkaline solution, with BDDGE concentration of at least 1 wt%. The optimised crosslinking conditions did not affect the apatite nano-crystals nucleated into self-assembling collagen fibres. The present work allowed to demonstrate that acting on BDDGE reaction parameters might be an useful tool to control the chemical-physical properties of bio-inspired scaffold suitable to heal wide osteochondral defects, even through arthroscopic procedure. PMID:23053811

  17. Design of a biomass-to-biorefinery logistics system through bio-inspired metaheuristic optimization considering multiple types of feedstocks

    NASA Astrophysics Data System (ADS)

    Trueba, Isidoro

    fossil fuels to biofuels. In many ways biomass is a unique renewable resource. It can be stored and transported relatively easily in contrast to renewable options such as wind and solar, which create intermittent electrical power that requires immediate consumption and a connection to the grid. This thesis presents two different models for the design optimization of a biomass-to-biorefinery logistics system through bio-inspired metaheuristic optimization considering multiple types of feedstocks. This work compares the performance and solutions obtained by two types of metaheuristic approaches; genetic algorithm and ant colony optimization. Compared to rigorous mathematical optimization methods or iterative algorithms, metaheuristics do not guarantee that a global optimal solution can be found on some class of problems. Problems with similar characteristics to the one presented in this thesis have been previously solved using linear programming, integer programming and mixed integer programming methods. However, depending on the type of problem, these mathematical or complete methods might need exponential computation time in the worst-case. This often leads to computation times too high for practical purposes. Therefore, this thesis develops two types of metaheuristic approaches for the design optimization of a biomass-to-biorefinery logistics system considering multiple types of feedstocks and shows that metaheuristics are highly suitable to solve hard combinatorial optimization problems such as the one addressed in this research work.

  18. Recent advances in high speed detection systems for ammunition plants

    NASA Astrophysics Data System (ADS)

    Klapmeier, K. M.

    1984-08-01

    The application of UV detection systems in radioactive environments and the application considerations of infrared, and combinations of ultraviolet and infrared are discussed. Recent developments in high speed single frequency infrared detection systems and their applications to munitions processes are also reviewed.

  19. Bio-inspired anti-oil-fouling chitosan-coated mesh for oil/water separation suitable for broad pH range and hyper-saline environments.

    PubMed

    Zhang, Shiyan; Lu, Fei; Tao, Lei; Liu, Na; Gao, Changrui; Feng, Lin; Wei, Yen

    2013-11-27

    Here, we report a bio-inspired chitosan (CS)-based mesh with high separation efficiency, oil-fouling repellency, and stability in a complex liquid environment. The surface of the CS coating maintains underwater superoleophobicity and low oil adhesion (<1 μN) in pure water and hyper-saline solutions, and it can keep stable special wettability in broad pH range environments after the CS mesh is fully cross-linked with glutaraldehyde and then reduced by sodium borohydride to form a stable carbon-nitrogen single bond. The separation process is solely gravity-driven, and the mesh can separate a range of different oil/water mixtures with >99% separation efficiency in hyper-saline and broad pH range conditions. We envision that such a separation method will be useful in oil spill cleanup and industrial oily wastewater treatment in extreme environments. PMID:24180691

  20. Direct comparison of the performance of a bio-inspired synthetic nickel catalyst and a [NiFe]-hydrogenase, both covalently attached to electrodes.

    PubMed

    Rodriguez-Maciá, Patricia; Dutta, Arnab; Lubitz, Wolfgang; Shaw, Wendy J; Rüdiger, Olaf

    2015-10-12

    The active site of hydrogenases has been a source of inspiration for the development of molecular catalysts. However, direct comparisons between molecular catalysts and enzymes have not been possible because different techniques are used to evaluate both types of catalysts, minimizing our ability to determine how far we have come in mimicking the enzymatic performance. The catalytic properties of the [Ni(P(Cy) 2 N(Gly) 2 )2 ](2+) complex with the [NiFe]-hydrogenase from Desulfovibrio vulgaris immobilized on a functionalized electrode were compared under identical conditions. At pH 7, the enzyme shows higher activity and lower overpotential with better stability, while at low pH, the molecular catalyst outperforms the enzyme in all respects. This is the first direct comparison of enzymes and molecular complexes, enabling a unique understanding of the benefits and detriments of both systems, and advancing our understanding of the utilization of these bio-inspired complexes in fuel cells. PMID:26140506

  1. Polyamine-Mediated Interfacial Assembly of rGO-ZnO Nanostructures: A Bio-inspired Approach and Enhanced Photocatalytic Properties.

    PubMed

    Reddy, Thuniki Naveen; Manna, Joydeb; Rana, Rohit K

    2015-09-01

    A bio-inspired approach for the fabrication of reduced graphene oxide (rGO) embedded ZnO nanostructure has been attempted to address issues pertaining to charge recombination and photocorrosion in ZnO for application as an effective photocatalyst. Herein we demonstrate the synthesis of rGO-ZnO nanostructures in a single step using polyamines, which simultaneously aid in the mineralization of ZnO nanostructures from zinc nitrate, reduction of graphene oxide (GO), and finally their assembly to form rGO-ZnO composite structures under environmentally benign conditions. The interspersed nanocomponents in the assembled heterostructures result in enhanced photocatalytic activity under UV light, indicating an effective charge separation of the excited electrons. Furthermore, the composite structure provides stability against photocorrosion for efficient recyclability of the catalyst. PMID:26317286

  2. Photochemical Hydrogen Generation Initiated by Oxidative Quenching of the Excited Ru(bpy)3 (2+) * by a Bio-Inspired [2Fe2S] Complex.

    PubMed

    Na, Yong; Wei, Peicheng; Zhou, Li

    2016-07-18

    A diiron dithiolate complex 1 containing 1,8-naphthalic anhydride bridge was prepared, which possessed the lowest reduction potential for the synthetic diiron complexes modeled on the active site of [FeFe] hydrogenase reported so far. For the first time, oxidative quenching of the excited Ru(bpy)3 (2+) * through electron transfer to a bio-inspired [2Fe2S] complex was corroborated. Hydrogen evolution, driven by visible light, was successfully observed for a three-component system, consisting of Ru(bpy)3 (2+) , complex 1, and EDTA as electron donor in aqueous/organic media. These results provide a basis and also opportunity to develop a photo water splitting system employing Fe-based catalysts without sacrificial electron donors. PMID:26879325

  3. Bio-inspired approach of the fluorescence emission properties in the scarabaeid beetle Hoplia coerulea (Coleoptera): Modeling by transfer-matrix optical simulations

    NASA Astrophysics Data System (ADS)

    Van Hooijdonk, Eloise; Berthier, Serge; Vigneron, Jean-Pol

    2012-12-01

    Scales of the scarabaeid beetle Hoplia coerulea (Coleoptera) contain fluorescent molecules embedded in a multilayer structure. The consequence of this source confinement is a modification of the fluorescence properties, i.e., an enhancement or inhibition of the emission of certain wavelengths. In this work, we propose a bio-inspired approach to this problem. In other words, we use numerical simulations based on the one-dimensional transfer-matrix formalism to investigate the influence of a Hoplia-like system on emission characteristics and, from the results, we deduce potential technical applications. We reveal that depending on the choice of some parameters (layer thickness, dielectric constant, and position of the emitting source in the structure), it is possible to enhance or inhibit the fluorescence emission for certain wavelengths. This observation could be of great interest to design new optical devices in the field of optoelectronic, solar cells, biosensors, etc.

  4. Biomechanical model of batoid (skates and rays) pectoral fins predicts the influence of skeletal structure on fin kinematics: implications for bio-inspired design.

    PubMed

    Russo, R S; Blemker, S S; Fish, F E; Bart-Smith, H

    2015-08-01

    Growing interest in the development of bio-inspired autonomous underwater vehicles (AUVs) has motivated research in understanding the mechanisms behind the propulsion systems of marine animals. For example, the locomotive behavior of rays (Batoidea) by movement of the pectoral fins is of particular interest due to their superior performance characteristics over contemporary AUV propulsion systems. To better understand the mechanics of pectoral fin propulsion, this paper introduces a biomechanical model that simulates how batoid skeletal structures function to achieve the swimming locomotion observed in nature. Two rays were studied, Dasyatis sabina (Atlantic ray), and Rhinoptera bonasus (cownose ray). These species were selected because they exhibit very different swimming styles (undulation versus oscillation), but all use primarily their pectoral fins for propulsion (unlike electric rays or guitarfishes). Computerized tomography scans of each species were taken to image the underlying structure, which reveal a complex system of cartilaginous joints and linkages. Data collected from these images were used to quantify the complete skeletal morphometry of each batoid fin. Morphological differences were identified in the internal cartilage arrangement between each species including variations in the orientation of the skeletal elements, or radials, and the joint patterns between them, called the inter-radial joint pattern. These data were used as the primary input into the biomechanical model to couple a given ray skeletal structure with various swimming motions. A key output of the model is an estimation of the uniaxial strain that develops in the skeletal connective tissue in order for the structure to achieve motions observed during swimming. Tensile load tests of this connective tissue were conducted to further investigate the implications of the material strain predictions. The model also demonstrates that changes in the skeletal architecture (e.g., joint

  5. Multimode nondestructive detecting method for high-speed rail defects

    NASA Astrophysics Data System (ADS)

    Sun, Mingjian; Cheng, Xingzhen; Wan, Guangnan; Liu, Ting; Fu, Ying; Wang, Yan

    2015-11-01

    It is very important to detect the surface defects of the high-speed rail for security concerns. A multimode detecting method, which integrates high resolution of optical image, high precision of photoacoustic detection and strong penetration of ultrasound detecting, is proposed for the rail defect detection. Utilizing the surface defect characteristics obtained from optical signal, the photoacoustic and ultrasound scanning region could be determined, and rail shallow and internal defect characteristics can be acquired subsequently. Eventually, fusing three modal signals mentioned above, the information of the entire rail defect, including type, extension trend and depth can be detected. It has been proved that the multimode method can improve the detecting efficiency, and enlarge the detection range in the meantime.

  6. Characterization of anthocyanin based dye-sensitized organic solar cells (DSSC) and modifications based on bio-inspired ion mobility improvements

    NASA Astrophysics Data System (ADS)

    Mawyin, Jose Amador

    The worldwide electrical energy consumption will increase from currently 10 terawatts to 30 terawatts by 2050. To decrease the current atmospheric CO2 would require our civilization to develop a 20 terawatts non-greenhouse emitting (renewable) electrical power generation capability. Solar photovoltaic electric power generation is thought to be a major component of proposed renewable energy-based economy. One approach to less costly, easily manufactured solar cells is the Dye-sensitized solar cells (DSSC) introduced by Greatzel and others. This dissertation describes the work focused on improving the performance of DSSC type solar cells. In particular parameters affecting dye-sensitized solar cells (DSSC) based on anthocyanin pigments extracted from California blackberries (Rubus ursinus) and bio-inspired modifications were analyzed and solar cell designs optimized. Using off-the-shelf materials DSSC were constructed and tested using a custom made solar spectrum simulator and photoelectric property characterization. This equipment facilitated the taking of automated I-V curve plots and the experimental determination of parameters such as open circuit voltage (V OC), short circuit current (JSC), fill factor (FF), etc. This equipment was used to probe the effect of various modifications such as changes in the annealing time and composition of the of the electrode counter-electrode. Solar cell optimization schemes included novel schemes such as solar spectrum manipulation to increase the percentage of the solar spectrum capable of generating power in the DSSC. Solar manipulation included light scattering and photon upconversion. Techniques examined here focused on affordable materials such as silica nanoparticles embedded inside a TiO2 matrix. Such materials were examined for controlled scattering of visible light and optimize light trapping within the matrix as well as a means to achieve photon up-energy-conversion using the Raman effect in silica nano-particles (due

  7. SPEED: the segmented pupil experiment for exoplanet detection

    NASA Astrophysics Data System (ADS)

    Martinez, P.; Preis, Olivier; Gouvret, C.; Dejonghe, J.; Daban, J.-B.; Spang, A.; Martinache, F.; Beaulieu, M.; Janin-Potiron, P.; Abe, L.; Fantei-Caujolle, Y.; Mattei, D.; Ottogalli, S.

    2014-07-01

    Searching for nearby exoplanets with direct imaging is one of the major scientific drivers for both space and groundbased programs. While the second generation of dedicated high-contrast instruments on 8-m class telescopes is about to greatly expand the sample of directly imaged planets, exploring the planetary parameter space to hitherto-unseen regions ideally down to Terrestrial planets is a major technological challenge for the forthcoming decades. This requires increasing spatial resolution and significantly improving high contrast imaging capabilities at close angular separations. Segmented telescopes offer a practical path toward dramatically enlarging telescope diameter from the ground (ELTs), or achieving optimal diameter in space. However, translating current technological advances in the domain of highcontrast imaging for monolithic apertures to the case of segmented apertures is far from trivial. SPEED - the segmented pupil experiment for exoplanet detection - is a new instrumental facility in development at the Lagrange laboratory for enabling strategies and technologies for high-contrast instrumentation with segmented telescopes. SPEED combines wavefront control including precision segment phasing architectures, wavefront shaping using two sequential high order deformable mirrors for both phase and amplitude control, and advanced coronagraphy struggled to very close angular separations (PIAACMC). SPEED represents significant investments and technology developments towards the ELT area and future spatial missions, and will offer an ideal cocoon to pave the road of technological progress in both phasing and high-contrast domains with complex/irregular apertures. In this paper, we describe the overall design and philosophy of the SPEED bench.

  8. Bio-inspired cofacial Fe porphyrin dimers for efficient electrocatalytic CO2 to CO conversion: Overpotential tuning by substituents at the porphyrin rings.

    PubMed

    Zahran, Zaki N; Mohamed, Eman A; Naruta, Yoshinori

    2016-01-01

    Efficient reduction of CO2 into useful carbon resources particularly CO is an essential reaction for developing alternate sources of fuels and for reducing the greenhouse effect of CO2. The binuclear Ni, Fe-containing carbon monoxide dehydrogenase (CODHs) efficiently catalyzes the reduction of CO2 to CO. The location of Ni and Fe at proper positions allows their cooperation for CO2 to CO conversion through a push-pull mechanism. Bio-inspired from CODHs, we used several cofacial porphyrin dimers with different substituents as suitable ligands for holding two Fe ions with suitable Fe-Fe separation distance to efficiently and selectively promote CO2 to CO conversion with high turnover frequencies, TOFs. The substituents on the porphyrin rings greatly affect the catalysis process. By introducing electron-withdrawing/-donating groups, e.g. electron-withdrawing perfluorophenyl, at all meso positions of the porphyrin rings, the catalysis overpotential, η was minimized by ≈0.3 V compared to that obtained by introducing electron-donating mesityl groups. The Fe porphyrin dimers among reported catalysts are the most efficient ones for CO2 to CO conversion. Control experiments indicate that the high performance of the current CO2 to CO conversion catalysts is due to the presence of binuclear Fe centers at suitable Fe-Fe separation distance. PMID:27087483

  9. Cu-doped carbon nitride: Bio-inspired synthesis of H2-evolving electrocatalysts using graphitic carbon nitride (g-C3N4) as a host material

    NASA Astrophysics Data System (ADS)

    Zou, Xiaoxin; Silva, Rafael; Goswami, Anandarup; Asefa, Tewodros

    2015-12-01

    Splitting water effectively to produce hydrogen (H2) requires the development of non-noble-metal electrocatalysts that are able to make this reaction feasible and energy efficient. Herein, we present a novel "structure upgrading" synthetic approach for the design and synthesis of bio-inspired hydrogen-evolving electrocatalysts based on earth-abundant elements. Using g-C3N4 - an inexpensive inorganic polymer material - as a host material for copper ions, novel Cu-doped g-C3N4 materials with supramolecular structure, efficient electrocatalytic activity and modest overpotentials for hydrogen evolution reaction (HER) are synthesized. Compared with most single-molecule analogs of hydrogenases that work only in organic media, the supramolecular Cu-doped g-C3N4 materials can serve as heterogeneous electrocatalysts with greater stability and good catalytic activity for HER in aqueous media. The materials afford a current density as high as 10 mA cm-2 at an overpotential as low as 390 mV, and work well in acidic media for, at least, 43 h.

  10. Highly robust hydrogen generation by bio-inspired Ir complexes for dehydrogenation of formic acid in water: Experimental and theoretical mechanistic investigations at different pH

    SciTech Connect

    Wang, Wan -Hui; Fujita, Etsuko; Ertem, Mehmed Z.; Xu, Shaoan; Onishi, Naoya; Manaka, Yuichi; Suna, Yuki; Kambayashi, Hide; Muckerman, James T.; Himeda, Yuichiro

    2015-07-30

    Hydrogen generation from formic acid (FA), one of the most promising hydrogen storage materials, has attracted much attention due to the demand for the development of renewable energy carriers. Catalytic dehydrogenation of FA in an efficient and green manner remains challenging. Here, we report a series of bio-inspired Ir complexes for highly robust and selective hydrogen production from FA in aqueous solutions without organic solvents or additives. One of these complexes bearing an imidazoline moiety (complex 6) achieved a turnover frequency (TOF) of 322,000 h⁻¹ at 100 °C, which is higher than ever reported. The novel catalysts are very stable and applicable in highly concentrated FA. For instance, complex 3 (1 μmol) affords an unprecedented turnover number (TON) of 2,050,000 at 60 °C. Deuterium kinetic isotope effect experiments and density functional theory (DFT) calculations employing a “speciation” approach demonstrated a change in the rate-determining step with increasing solution pH. This study provides not only more insight into the mechanism of dehydrogenation of FA but also offers a new principle for the design of effective homogeneous organometallic catalysts for H₂ generation from FA.

  11. Highly robust hydrogen generation by bio-inspired Ir complexes for dehydrogenation of formic acid in water: Experimental and theoretical mechanistic investigations at different pH

    DOE PAGESBeta

    Wang, Wan -Hui; Fujita, Etsuko; Ertem, Mehmed Z.; Xu, Shaoan; Onishi, Naoya; Manaka, Yuichi; Suna, Yuki; Kambayashi, Hide; Muckerman, James T.; Himeda, Yuichiro

    2015-07-30

    Hydrogen generation from formic acid (FA), one of the most promising hydrogen storage materials, has attracted much attention due to the demand for the development of renewable energy carriers. Catalytic dehydrogenation of FA in an efficient and green manner remains challenging. Here, we report a series of bio-inspired Ir complexes for highly robust and selective hydrogen production from FA in aqueous solutions without organic solvents or additives. One of these complexes bearing an imidazoline moiety (complex 6) achieved a turnover frequency (TOF) of 322,000 h⁻¹ at 100 °C, which is higher than ever reported. The novel catalysts are very stablemore » and applicable in highly concentrated FA. For instance, complex 3 (1 μmol) affords an unprecedented turnover number (TON) of 2,050,000 at 60 °C. Deuterium kinetic isotope effect experiments and density functional theory (DFT) calculations employing a “speciation” approach demonstrated a change in the rate-determining step with increasing solution pH. This study provides not only more insight into the mechanism of dehydrogenation of FA but also offers a new principle for the design of effective homogeneous organometallic catalysts for H₂ generation from FA.« less

  12. Concepts and Development of Bio-Inspired Distributed Embedded Wired/Wireless Sensor Array Architectures for Acoustic Wave Sensing in Integrated Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Ghoshal, Anindya; Prosser, William H.; Kirikera, Goutham; Schulz, Mark J.; Hughes, Derke J.; Orisamolu, Wally

    2003-01-01

    This paper discusses the modeling of acoustic emissions in plate structures and their sensing by embedded or surface bonded piezoelectric sensor arrays. Three different modeling efforts for acoustic emission (AE) wave generation and propagation are discussed briefly along with their advantages and disadvantages. Continuous sensors placed at right angles on a plate are being discussed as a new approach to measure and locate the source of acoustic waves. Evolutionary novel signal processing algorithms and bio-inspired distributed sensor array systems are used on large structures and integrated aerospace vehicles for AE source localization and preliminary results are presented. These systems allow for a great reduction in the amount of data that needs to be processed and also reduce the chances of false alarms from ambient noises. It is envisioned that these biomimetic sensor arrays and signal processing techniques will be useful for both wireless and wired sensor arrays for real time health monitoring of large integrated aerospace vehicles and earth fixed civil structures. The sensor array architectures can also be used with other types of sensors and for other applications.

  13. Folic acid bio-inspired route for facile synthesis of AuPt nanodendrites as enhanced electrocatalysts for methanol and ethanol oxidation reactions

    NASA Astrophysics Data System (ADS)

    Wang, Ai-Jun; Ju, Ke-Jian; Zhang, Qian-Li; Song, Pei; Wei, Jie; Feng, Jiu-Ju

    2016-09-01

    Folic acid (FA), as an important biomolecule in cell division and growth, is firstly employed as the structure director and stabilizing agent for controlled synthesis of uniform Au65Pt35 nanodendrites (NDs) by a one-pot wet-chemical bio-inspired route at room temperature. No pre-seed, template, organic solvent, polymer, surfactant or complex instrument is involved. The products are mainly characterized by transmission electron microscopy (TEM), high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), and X-Ray photoelectron spectroscopy (XPS). The architectures have enlarged electrochemically active surface area (60.6 m2 gPt-1), enhanced catalytic activity and durability for methanol and ethanol oxidation in contrast with commercial Pt black and the other AuPt alloys by tuning the molar ratios of Au to Pt (e.g., Au31Pt69 and Au82Pt18 nanoparticles). This strategy would be applied to fabricate other bimetallic nanocatalysts in fuel cells.

  14. A new numerical approach to solve Thomas-Fermi model of an atom using bio-inspired heuristics integrated with sequential quadratic programming.

    PubMed

    Raja, Muhammad Asif Zahoor; Zameer, Aneela; Khan, Aziz Ullah; Wazwaz, Abdul Majid

    2016-01-01

    In this study, a novel bio-inspired computing approach is developed to analyze the dynamics of nonlinear singular Thomas-Fermi equation (TFE) arising in potential and charge density models of an atom by exploiting the strength of finite difference scheme (FDS) for discretization and optimization through genetic algorithms (GAs) hybrid with sequential quadratic programming. The FDS procedures are used to transform the TFE differential equations into a system of nonlinear equations. A fitness function is constructed based on the residual error of constituent equations in the mean square sense and is formulated as the minimization problem. Optimization of parameters for the system is carried out with GAs, used as a tool for viable global search integrated with SQP algorithm for rapid refinement of the results. The design scheme is applied to solve TFE for five different scenarios by taking various step sizes and different input intervals. Comparison of the proposed results with the state of the art numerical and analytical solutions reveals that the worth of our scheme in terms of accuracy and convergence. The reliability and effectiveness of the proposed scheme are validated through consistently getting optimal values of statistical performance indices calculated for a sufficiently large number of independent runs to establish its significance. PMID:27610319

  15. High-Speed Observer: Automated Streak Detection in SSME Plumes

    NASA Technical Reports Server (NTRS)

    Rieckoff, T. J.; Covan, M.; OFarrell, J. M.

    2001-01-01

    A high frame rate digital video camera installed on test stands at Stennis Space Center has been used to capture images of Space Shuttle main engine plumes during test. These plume images are processed in real time to detect and differentiate anomalous plume events occurring during a time interval on the order of 5 msec. Such speed yields near instantaneous availability of information concerning the state of the hardware. This information can be monitored by the test conductor or by other computer systems, such as the integrated health monitoring system processors, for possible test shutdown before occurrence of a catastrophic engine failure.

  16. Sequentially-coupled space-time FSI analysis of bio-inspired flapping-wing aerodynamics of an MAV

    NASA Astrophysics Data System (ADS)

    Takizawa, Kenji; Tezduyar, Tayfun E.; Kostov, Nikolay

    2014-08-01

    We present a sequentially-coupled space-time (ST) computational fluid-structure interaction (FSI) analysis of flapping-wing aerodynamics of a micro aerial vehicle (MAV). The wing motion and deformation data, whether prescribed fully or partially, is from an actual locust, extracted from high-speed, multi-camera video recordings of the locust in a wind tunnel. The core computational FSI technology is based on the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) formulation. This is supplemented with using NURBS basis functions in temporal representation of the wing and mesh motion, and in remeshing. Here we use the version of the DSD/SST formulation derived in conjunction with the variational multiscale (VMS) method, and this version is called "DSD/SST-VMST." The structural mechanics computations are based on the Kirchhoff-Love shell model. The sequential-coupling technique is applicable to some classes of FSI problems, especially those with temporally-periodic behavior. We show that it performs well in FSI computations of the flapping-wing aerodynamics we consider here. In addition to the straight-flight case, we analyze cases where the MAV body has rolling, pitching, or rolling and pitching motion. We study how all these influence the lift and thrust.

  17. High-Speed Edge-Detecting Line Scan Smart Camera

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F.

    2012-01-01

    A high-speed edge-detecting line scan smart camera was developed. The camera is designed to operate as a component in a NASA Glenn Research Center developed inlet shock detection system. The inlet shock is detected by projecting a laser sheet through the airflow. The shock within the airflow is the densest part and refracts the laser sheet the most in its vicinity, leaving a dark spot or shadowgraph. These spots show up as a dip or negative peak within the pixel intensity profile of an image of the projected laser sheet. The smart camera acquires and processes in real-time the linear image containing the shock shadowgraph and outputting the shock location. Previously a high-speed camera and personal computer would perform the image capture and processing to determine the shock location. This innovation consists of a linear image sensor, analog signal processing circuit, and a digital circuit that provides a numerical digital output of the shock or negative edge location. The smart camera is capable of capturing and processing linear images at over 1,000 frames per second. The edges are identified as numeric pixel values within the linear array of pixels, and the edge location information can be sent out from the circuit in a variety of ways, such as by using a microcontroller and onboard or external digital interface to include serial data such as RS-232/485, USB, Ethernet, or CAN BUS; parallel digital data; or an analog signal. The smart camera system can be integrated into a small package with a relatively small number of parts, reducing size and increasing reliability over the previous imaging system..

  18. A Bio-Inspired, Motion-Based Analysis of Crowd Behavior Attributes Relevance to Motion Transparency, Velocity Gradients, and Motion Patterns

    PubMed Central

    Raudies, Florian; Neumann, Heiko

    2012-01-01

    The analysis of motion crowds is concerned with the detection of potential hazards for individuals of the crowd. Existing methods analyze the statistics of pixel motion to classify non-dangerous or dangerous behavior, to detect outlier motions, or to estimate the mean throughput of people for an image region. We suggest a biologically inspired model for the analysis of motion crowds that extracts motion features indicative for potential dangers in crowd behavior. Our model consists of stages for motion detection, integration, and pattern detection that model functions of the primate primary visual cortex area (V1), the middle temporal area (MT), and the medial superior temporal area (MST), respectively. This model allows for the processing of motion transparency, the appearance of multiple motions in the same visual region, in addition to processing opaque motion. We suggest that motion transparency helps to identify “danger zones” in motion crowds. For instance, motion transparency occurs in small exit passages during evacuation. However, motion transparency occurs also for non-dangerous crowd behavior when people move in opposite directions organized into separate lanes. Our analysis suggests: The combination of motion transparency and a slow motion speed can be used for labeling of candidate regions that contain dangerous behavior. In addition, locally detected decelerations or negative speed gradients of motions are a precursor of danger in crowd behavior as are globally detected motion patterns that show a contraction toward a single point. In sum, motion transparency, image speeds, motion patterns, and speed gradients extracted from visual motion in videos are important features to describe the behavioral state of a motion crowd. PMID:23300930

  19. Rotor Speed Detection Method for Vector Control of Induction Motor without Speed Sensor Utilizing Slot Harmonics

    NASA Astrophysics Data System (ADS)

    Kiyotake, Hirofumi; Shinohara, Katsuji; Yamamoto, Kichiro

    Speed sensorless vector controlled induction motor drives are the standard choice in many industrial applications, but this can hardly control torque and rotor speed at low speed. Recently, a method based on the high-frequency signal injection has been studied. This paper presents a method for suppressing the effects of the saturation saliency by using high pass filter, and a new approach to estimate the rotor speed. The effectiveness of these methods are demonstrated through experimental results showing both good suppression of saturation harmonics and good sensorless speed control at low speed.

  20. On the synthesis of a bio-inspired dual-cellular fluidic flexible matrix composite adaptive structure based on a non-dimensional dynamics model

    NASA Astrophysics Data System (ADS)

    Li, Suyi; Wang, K. W.

    2013-01-01

    A recent study investigated the dynamic characteristics of an adaptive structure concept featuring dual fluidic flexible matrix composite (F2MC) cells inspired by the configuration of plant cells and cell walls. This novel bio-inspired system consists of two F2MC cells with different fiber angles connected through internal fluid circuits. It was discovered that the dual F2MC cellular structure can be characterized as a two degree of freedom damped mass-spring oscillator, and can be utilized as a vibration absorber or an enhanced actuator under different operation conditions. These results demonstrated that the concept is promising and further investigations are needed to develop methodologies for synthesizing future multi-cellular F2MC structural systems. While interesting, the previous study focused on specific case studies and analysis. That is, the outcome did not provide insight that could be generalized, or tools for synthesizing a multiple F2MC cellular structure. This paper attempts to address this important issue by developing a non-dimensional dynamic model, which reveals good physical insights as well as identifying crucial constitutive parameters for F2MC cellular design. Working with these parameters, rather than physical variables, can greatly simplify the mathematics involved in the study. A synthesis tool is then developed for the dual-cellular structure, and it is found that for each set of achievable target poles and zero, there exist multiple F2MC cellular designs, forming a design space. The presented physical insights and synthesis tool for the dual-cellular structure will be the building blocks for future investigation on cellular structures with a larger number of cells.

  1. High-speed detection of DNA translocation in nanopipettes.

    PubMed

    Fraccari, Raquel L; Ciccarella, Pietro; Bahrami, Azadeh; Carminati, Marco; Ferrari, Giorgio; Albrecht, Tim

    2016-04-14

    We present a high-speed electrical detection scheme based on a custom-designed CMOS amplifier which allows the analysis of DNA translocation in glass nanopipettes on a microsecond timescale. Translocation of different DNA lengths in KCl electrolyte provides a scaling factor of the DNA translocation time equal to p = 1.22, which is different from values observed previously with nanopipettes in LiCl electrolyte or with nanopores. Based on a theoretical model involving electrophoresis, hydrodynamics and surface friction, we show that the experimentally observed range of p-values may be the result of, or at least be affected by DNA adsorption and friction between the DNA and the substrate surface. PMID:26985713

  2. The interaction of Hg(2+) and trivalent ions with two new fluorescein bio-inspired dual colorimetric/fluorimetric probes.

    PubMed

    Gonçalves, A C; Pilla, V; Oliveira, E; Santos, S M; Capelo, J L; Dos Santos, A A; Lodeiro, C

    2016-06-21

    Two new luminescent compounds containing fluorescein-amino acid units have been designed and synthesized via an ester linkage between a fluorescein ethyl ester and Boc-Ser(TBDMS)-OH or Boc-Cys(4-MeBzl)-OH, and their photophysical properties have been explored. The optical response of both compounds (2 and 3) towards the metal ions Na(+), K(+), Hg(+), Ag(+), Ca(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), Hg(2+), Al(3+), Fe(3+), Ga(3+)and Cr(3+) was investigated in pure acetonitrile and in acetonitrile/water mixtures. A strong CHEF (Chelation-Enhanced Fluorescence) effect was observed with all the trivalent metals and Hg(2+) ions in both solvents. UV-vis absorption, steady state and time resolved emission spectroscopy methods were employed. The results show the formation of mononuclear complexes with Al(3+), Fe(3+), Ga(3+), Cr(3+), and Hg(2+). Theoretical calculation using Density Functional Theory was performed in order to obtain atomistic insights into the coordination geometry of Al(3+) and Hg(2+) to the fluorescein 3, which is in accordance with the experimental stoichiometry results obtained in the Job's plot method. Among the active cations, the minimum detectable amount is under 1 μM for most of the cases in both absorption and fluorescence spectroscopy methods. PMID:27193690

  3. Development and testing of bio-inspired microelectromechanical pressure sensor arrays for increased situational awareness for marine vehicles

    NASA Astrophysics Data System (ADS)

    Dusek, J.; Kottapalli, A. G. P.; Woo, M. E.; Asadnia, M.; Miao, J.; Lang, J. H.; Triantafyllou, M. S.

    2013-01-01

    The lateral line found on most species of fish is a sensory organ without analog in humans. Using sensory feedback from the lateral line, fish are able to track prey, school, avoid obstacles, and detect vortical flow structures. Composed of both a superficial component, and a component contained within canals beneath the fish’s skin, the lateral line acts in a similar fashion to an array of differential pressure sensors. In an effort to enhance the situational and environmental awareness of marine vehicles, lateral-line-inspired pressure sensor arrays were developed to mimic the enhanced sensory capabilities observed in fish. Three flexible and waterproof pressure sensor arrays were fabricated for use as a surface-mounted ‘smart skin’ on marine vehicles. Two of the sensor arrays were based around the use of commercially available piezoresistive sensor dies, with innovative packaging schemes to allow for flexibility and underwater operation. The sensor arrays employed liquid crystal polymer and flexible printed circuit board substrates with metallic circuits and silicone encapsulation. The third sensor array employed a novel nanocomposite material set that allowed for the fabrication of a completely flexible sensor array. All three sensors were surface mounted on the curved hull of an autonomous kayak vehicle, and tested in both pool and reservoir environments. Results demonstrated that all three sensors were operational while deployed on the autonomous vehicle, and provided an accurate means for monitoring the vehicle dynamics.

  4. High-speed detection of DNA translocation in nanopipettes

    NASA Astrophysics Data System (ADS)

    Fraccari, Raquel L.; Ciccarella, Pietro; Bahrami, Azadeh; Carminati, Marco; Ferrari, Giorgio; Albrecht, Tim

    2016-03-01

    We present a high-speed electrical detection scheme based on a custom-designed CMOS amplifier which allows the analysis of DNA translocation in glass nanopipettes on a microsecond timescale. Translocation of different DNA lengths in KCl electrolyte provides a scaling factor of the DNA translocation time equal to p = 1.22, which is different from values observed previously with nanopipettes in LiCl electrolyte or with nanopores. Based on a theoretical model involving electrophoresis, hydrodynamics and surface friction, we show that the experimentally observed range of p-values may be the result of, or at least be affected by DNA adsorption and friction between the DNA and the substrate surface.We present a high-speed electrical detection scheme based on a custom-designed CMOS amplifier which allows the analysis of DNA translocation in glass nanopipettes on a microsecond timescale. Translocation of different DNA lengths in KCl electrolyte provides a scaling factor of the DNA translocation time equal to p = 1.22, which is different from values observed previously with nanopipettes in LiCl electrolyte or with nanopores. Based on a theoretical model involving electrophoresis, hydrodynamics and surface friction, we show that the experimentally observed range of p-values may be the result of, or at least be affected by DNA adsorption and friction between the DNA and the substrate surface. Electronic supplementary information (ESI) available: Gel electrophoresis confirming lengths and purity of DNA samples, comparison between Axopatch 200B and custom-built setup, comprehensive low-noise amplifier characterization, representative I-V curves of nanopipettes used, typical scatter plots of τ vs. peak amplitude for the four LDNA's used, table of most probable τ values, a comparison between different fitting models for the DNA translocation time distribution, further details on the stochastic numerical simulation of the scaling statistics and the derivation of the extended

  5. Bio-inspired dynamic robots

    NASA Astrophysics Data System (ADS)

    Rudolph, Alan S.; Wax, Steven G.; Christodoulou, Leo

    2003-09-01

    The unique performance of biological systems across a wide spectrum of phylogenetic species has historically provided inspirations for roboticists in new designs and fabrication of new robotic platforms. Of particular interest to a number of important applications is to create dynamic robots able to adapt to a change in their world, unplanned events that are sometimes unexpected, and sometimes unstable, harsh conditions. It is likely that the exploring dynamics in biological systems will continue to provide rich solutions to attaining robots capable of more complex tasks for this purpose. This is because the long-term design process of evolution utilizes a natural selection process that responds to such changes. Recently, there have been significant advances across a number of interdisciplinary efforts that have generated new capabilities in biorobotics. Whole body dynamics that capture the force dynamics and functional stability of legged systems over rough terrain have been elucidated and applied in legged robotic systems. Exploying the force dynamics of flapping winged insect flight has provided key discoveries and enabled the fabrication of new micro air vehicles. New classes of materials are being developed that emulate the ability of natural muscle, capturing the compliant and soft subtle movement and performance of biological appendages. In addition, classes of new multifunctional materials are being developed to enable the design of biorobotics with the structural and functional efficiency of living organisms. Optical flow and other sensors based on the principles of invertebrate vision have been implemented on robotic platforms for autonomous robotic guidance and control. These fundamental advances have resulted in the emergence of a new generation of bioinspired dynamic robots which show significant performance improvements in early prototype testing and that could someday be useful in a number of significant applications such as search and rescue and entertainment.

  6. Detecting and Blocking Network Attacks at Ultra High Speeds

    SciTech Connect

    Paxson, Vern

    2010-11-29

    Stateful, in-depth, in-line traffic analysis for intrusion detection and prevention has grown increasingly more difficult as the data rates of modern networks rise. One point in the design space for high-performance network analysis - pursued by a number of commercial products - is the use of sophisticated custom hardware. For very high-speed processing, such systems often cast the entire analysis process in ASICs. This project pursued a different architectural approach, which we term Shunting. Shunting marries a conceptually quite simple hardware device with an Intrusion Prevention System (IPS) running on commodity PC hardware. The overall design goal is was to keep the hardware both cheap and readily scalable to future higher speeds, yet also retain the unparalleled flexibility that running the main IPS analysis in a full general-computing environment provides. The Shunting architecture we developed uses a simple in-line hardware element that maintains several large state tables indexed by packet header fields, including IP/TCP flags, source and destination IP addresses, and connection tuples. The tables yield decision values the element makes on a packet-by-packet basis: forward the packet, drop it, or divert ('shunt') it through the IPS (the default). By manipulating table entries, the IPS can, on a fine-grained basis: (i) specify the traffic it wishes to examine, (ii) directly block malicious traffic, and (iii) 'cut through' traffic streams once it has had an opportunity to 'vet' them, or (iv) skip over large items within a stream before proceeding to further analyze it. For the Shunting architecture to yield benefits, it needs to operate in an environment for which the monitored network traffic has the property that - after proper vetting - much of it can be safely skipped. This property does not universally hold. For example, if a bank needs to examine all Web traffic involving its servers for regulatory compliance, then a monitor in front of one of the bank

  7. An infrared small target detection algorithm based on high-speed local contrast method

    NASA Astrophysics Data System (ADS)

    Cui, Zheng; Yang, Jingli; Jiang, Shouda; Li, Junbao

    2016-05-01

    Small-target detection in infrared imagery with a complex background is always an important task in remote sensing fields. It is important to improve the detection capabilities such as detection rate, false alarm rate, and speed. However, current algorithms usually improve one or two of the detection capabilities while sacrificing the other. In this letter, an Infrared (IR) small target detection algorithm with two layers inspired by Human Visual System (HVS) is proposed to balance those detection capabilities. The first layer uses high speed simplified local contrast method to select significant information. And the second layer uses machine learning classifier to separate targets from background clutters. Experimental results show the proposed algorithm pursue good performance in detection rate, false alarm rate and speed simultaneously.

  8. High speed microscopy techniques for signaling detection in live cells

    NASA Astrophysics Data System (ADS)

    de Mauro, C.; Cecchetti, C. A.; Alfieri, D.; Borile, Giulia; Urbani, A.; Mongillo, M.; Pavone, F. S.

    2014-05-01

    Alterations in intracellular cardiomyocyte calcium handling have a key role in initiating and sustaining arrhythmias. Arrhythmogenic calcium leak from sarcoplasmic reticulum (SR) can be attributed to all means by which calcium exits the SR store in an abnormal fashion. Abnormal SR calcium exit maymanifest as intracellular Ca2+ sparks and/or Ca2+ waves. Ca2+ signaling in arrhythmogenesis has been mainly studied in isolated cardiomyocytes and given that the extracellular matrix influences both Ca2+ and membrane potential dynamics in the intact heart and underlies environmentally mediated changes, understanding how Ca2+ and voltage are regulated in the intact heart will represent a tremendous advancement in the understanding of arrhythmogenic mechanisms. Using novel high-speed multiphoton microscopy techinques, such as multispot and random access, we investigated animal models with inherited and acquired arrhythmias to assess the role of Ca2+ and voltage signals as arrhythmia triggers in cell and subcellular components of the intact heart and correlate these with electrophysiology.

  9. Fault detection in rotary blood pumps using motor speed response.

    PubMed

    Soucy, Kevin G; Koenig, Steven C; Sobieski, Michael A; Slaughter, Mark S; Giridharan, Guruprasad A

    2013-01-01

    Clinical acceptance of ventricular assist devices (VADs) as long-term heart failure therapy requires safe and effective circulatory support for a minimum of 5 years. Yet, VAD failure beyond 2 years of support is still a concern. Currently, device controllers cannot consistently predict VAD failure modes, and undetected VAD faults may lead to catastrophic device failure. To minimize this risk, a model-based algorithm for reliable VAD fault detection that only requires VAD revolutions per minute (rpm) was developed. The algorithm was tested using computer models of the human cardiovascular system simulating heart failure and axial flow (AF) or centrifugal flow (CF) VADs. Ventricular assist device rpm was monitored after a step down of motor current for normal and simulated fault conditions (>750 faults). The ability to detect fault conditions with 1%, 5%, and 10% rpm measurement noise was evaluated. All failure modes affected the VAD rpm responses to the motor current step down. Fault detection rates were >95% for AF and >89% for CF VADs, even with 10% rpm measurement noise. The VAD rpm responses were significantly altered by blood viscosity (3.5-6.2 cP), which should be accounted for in clinical application. The proposed VAD fault detection algorithm may deliver a convenient and nonintrusive way to minimize catastrophic device failures. PMID:23820281

  10. Comparison of high speed imaging technique to laser vibrometry for detection of vibration information from objects

    NASA Astrophysics Data System (ADS)

    Paunescu, Gabriela; Lutzmann, Peter; Göhler, Benjamin; Wegner, Daniel

    2015-10-01

    The development of camera technology in recent years has made high speed imaging a reliable method in vibration and dynamic measurements. The passive recovery of vibration information from high speed video recordings was reported in several recent papers. A highly developed technique, involving decomposition of the input video into spatial subframes to compute local motion signals, allowed an accurate sound reconstruction. A simpler technique based on image matching for vibration measurement was also reported as efficient in extracting audio information from a silent high speed video. In this paper we investigate and discuss the sensitivity and the limitations of the high speed imaging technique for vibration detection in comparison to the well-established Doppler vibrometry technique. Experiments on the extension of the high speed imaging method to longer range applications are presented.

  11. Lightning detection network averts damage and speeds restoration

    SciTech Connect

    Bernstein, R.; Samm, R.; Cummins, K.; Pyle, R.; Tuel, J.

    1996-04-01

    This article describes new tools to track thunderstorms for advance warning, enabling utilities to reduce damage and shorten repair time. Based on an extensive survey of US power utilities, lightning is the single largest cause of outages on distribution and transmission systems in lightning prone areas. But now with the aid of a network of electromagnetic sensors, computer systems, and satellite communications, the National Lightning Detection Network{trademark} (NLDN) helps utilities prepare for storms. Utilities in the path of intense lightning storms can prepare for storms, alert repair crews, and arrange for help from neighboring utilities. Real-time lightning data has been shown to reduce maintenance costs by shortening the thunder-storm-watch period and to improve reliability by allowing prepositioning of repair crews. Also, using line failure history, designers can analyze the lightning and line historical data and prioritize line upgrades to protect them from future storms by employing additional protection. Documented evidence available from the NLDN system helps utilities prove the time and location of lightning strikes, quickly resolving insurance claims. This network is a product of two EPRI research projects (RP3669 and RP2741).

  12. Determination of acoustic speed for improving leak detection and location in gas pipelines

    NASA Astrophysics Data System (ADS)

    Li, Shuaiyong; Wen, Yumei; Li, Ping; Yang, Jin; Yang, Lili

    2014-02-01

    The commonly used cross-correlation technique for leak location requires that the acoustic speed is known and invariable. In practice, the gas leakage-induced acoustic waves propagate along multiple paths including in-pipe gas and pipe wall, and the acoustic waves in different transmission paths exhibit different acoustic speeds and different dispersive behaviors, which bring a great challenge for leak detection and location in the gas pipelines. In this study, based on the vibration theory of cylindrical elastic thin shell, the wavenumber formulae in different transmission paths are derived to predict the acoustic speeds and the acoustical coupling between the in-pipe gas and the pipe wall is analyzed to determine the dominant transmission path. In addition, the velocity dispersions in the dominant transmission path are suppressed by selection of a characteristic frequency band of the gas leakage-induced acoustic waves. The theoretical predictions are verified in the experiment and the results show that the theoretical acoustic speed is slightly larger than the measured acoustic speed. Thus, the theoretical acoustic speed formula is modified considering the effect of the structural loss factor and consequently the location error using the modified acoustic speed is reduced by two times compared to that using the theoretical acoustic speed.

  13. Determination of acoustic speed for improving leak detection and location in gas pipelines.

    PubMed

    Li, Shuaiyong; Wen, Yumei; Li, Ping; Yang, Jin; Yang, Lili

    2014-02-01

    The commonly used cross-correlation technique for leak location requires that the acoustic speed is known and invariable. In practice, the gas leakage-induced acoustic waves propagate along multiple paths including in-pipe gas and pipe wall, and the acoustic waves in different transmission paths exhibit different acoustic speeds and different dispersive behaviors, which bring a great challenge for leak detection and location in the gas pipelines. In this study, based on the vibration theory of cylindrical elastic thin shell, the wavenumber formulae in different transmission paths are derived to predict the acoustic speeds and the acoustical coupling between the in-pipe gas and the pipe wall is analyzed to determine the dominant transmission path. In addition, the velocity dispersions in the dominant transmission path are suppressed by selection of a characteristic frequency band of the gas leakage-induced acoustic waves. The theoretical predictions are verified in the experiment and the results show that the theoretical acoustic speed is slightly larger than the measured acoustic speed. Thus, the theoretical acoustic speed formula is modified considering the effect of the structural loss factor and consequently the location error using the modified acoustic speed is reduced by two times compared to that using the theoretical acoustic speed. PMID:24593385

  14. High-Speed Incoming Infrared Target Detection by Fusion of Spatial and Temporal Detectors

    PubMed Central

    Kim, Sungho

    2015-01-01

    This paper presents a method for detecting high-speed incoming targets by the fusion of spatial and temporal detectors to achieve a high detection rate for an active protection system (APS). The incoming targets have different image velocities according to the target-camera geometry. Therefore, single-target detector-based approaches, such as a 1D temporal filter, 2D spatial filter and 3D matched filter, cannot provide a high detection rate with moderate false alarms. The target speed variation was analyzed according to the incoming angle and target velocity. The speed of the distant target at the firing time is almost stationary and increases slowly. The speed varying targets are detected stably by fusing the spatial and temporal filters. The stationary target detector is activated by an almost zero temporal contrast filter (TCF) and identifies targets using a spatial filter called the modified mean subtraction filter (M-MSF). A small motion (sub-pixel velocity) target detector is activated by a small TCF value and finds targets using the same spatial filter. A large motion (pixel-velocity) target detector works when the TCF value is high. The final target detection is terminated by fusing the three detectors based on the threat priority. The experimental results of the various target sequences show that the proposed fusion-based target detector produces the highest detection rate with an acceptable false alarm rate. PMID:25815448

  15. Experimental study of high-speed imaging detection system for small bubbles in water

    NASA Astrophysics Data System (ADS)

    Du, Peng; Yang, Kecheng; Xia, Min; Li, Wei

    2015-10-01

    Small bubbles are widely present in the marine environment, the presence of small bubbles generated by whitecaps, microorganisms, ships sailing will greatly affect the optical properties of seawater. A lot of work has been carried out around the detection of small bubbles, this article will introduce a method of detecting small bubbles underwater with the way of high-speed imaging underwater. The optical mechanisms to measure the parameters of small bubbles are mainly high-speed photography, laser interferometry and holography. The advantages of high-speed photography are intuitive and low cost, the experimenters can real-time monitor the shooting circumstances, and can obtain more detailed parameters concerning the small bubbles. The paper also discusses an experimental method of high-speed imaging for small bubbles in water, that is to get a cooperative target in the back of the bubbles, then shoot the bubbles, and a lot of experiments with the two methods have been done. In order to compare the imaging quality of the two sets of experiments intuitively, the histograms and the results of edge detecting of the pictures have been given. After compared the results, it is found that the images are clearer and higher in contrast in the case of there is a cooperative target behind the bubbles, and with the imaging rate of the high-speed camera increases, the image quality is significantly reduced.

  16. Dark energy with non-adiabatic sound speed: initial conditions and detectability

    SciTech Connect

    Ballesteros, Guillermo; Lesgourgues, Julien E-mail: julien.lesgourgues@cern.ch

    2010-10-01

    Assuming that the universe contains a dark energy fluid with a constant linear equation of state and a constant sound speed, we study the prospects of detecting dark energy perturbations using CMB data from Planck, cross-correlated with galaxy distribution maps from a survey like LSST. We update previous estimates by carrying a full exploration of the mock data likelihood for key fiducial models. We find that it will only be possible to exclude values of the sound speed very close to zero, while Planck data alone is not powerful enough for achieving any detection, even with lensing extraction. We also discuss the issue of initial conditions for dark energy perturbations in the radiation and matter epochs, generalizing the usual adiabatic conditions to include the sound speed effect. However, for most purposes, the existence of attractor solutions renders the perturbation evolution nearly independent of these initial conditions.

  17. An optical system for detecting 3D high-speed oscillation of a single ultrasound microbubble

    PubMed Central

    Liu, Yuan; Yuan, Baohong

    2013-01-01

    As contrast agents, microbubbles have been playing significant roles in ultrasound imaging. Investigation of microbubble oscillation is crucial for microbubble characterization and detection. Unfortunately, 3-dimensional (3D) observation of microbubble oscillation is challenging and costly because of the bubble size—a few microns in diameter—and the high-speed dynamics under MHz ultrasound pressure waves. In this study, a cost-efficient optical confocal microscopic system combined with a gated and intensified charge-coupled device (ICCD) camera were developed to detect 3D microbubble oscillation. The capability of imaging microbubble high-speed oscillation with much lower costs than with an ultra-fast framing or streak camera system was demonstrated. In addition, microbubble oscillations along both lateral (x and y) and axial (z) directions were demonstrated. Accordingly, this system is an excellent alternative for 3D investigation of microbubble high-speed oscillation, especially when budgets are limited. PMID:24049677

  18. High-Speed Observer: Automated Streak Detection for the Aerospike Engine

    NASA Technical Reports Server (NTRS)

    Rieckhoff, T. J.; Covan, M. A.; OFarrell, J. M.

    2001-01-01

    A high-frame-rate digital video camera, installed on test stands at Stennis Space Center (SSC), has been used to capture images of the aerospike engine plume during test. These plume images are processed in real time to detect and differentiate anomalous plume events. Results indicate that the High-Speed Observer (HSO) system can detect anomalous plume streaking events that are indicative of aerospike engine malfunction.

  19. High Speed All Optical Nyquist Signal Generation and Full-band Coherent Detection

    PubMed Central

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan

    2014-01-01

    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems. PMID:25142269

  20. Effect of chewing speed on the detection of a foreign object in food.

    PubMed

    Paphangkorakit, J; Ladsena, V; Rukyuttithamkul, T; Khamtad, T

    2016-03-01

    Accidentally biting hard on a piece of hard foreign object in food is among the causes of tooth fracturing and could be associated with oral sensibility. This study has investigated the effect of chewing speed on the ability to detect a foreign object in food in human. Fourteen healthy subjects were asked to randomly chew one of 10 cooked rice balls, five of which containing a foreign object made from a tiny uncooked rice grain, until they detected the rice grain. Each subject chewed the test foods both at 50 (slow) and 100 (fast) chews min(-1). The accuracy of detection and the number of chews before detection (CBD) were recorded and compared between the two chewing speeds using paired t-tests. The results showed that almost all subjects detected the foreign object by biting. The accuracy of detection was more than 90% and not significantly different between slow and fast chewing but the mean CBD in slow chewing (11·7 ± 1·3 chews) was significantly different from that in fast chewing (20·7 ± 1·9 chews; P < 0·001). The study showed that slow chewers required less number of chews before a foreign object in food could be detected and was, presumably, more effective in detecting the object compared to fast chewers. If each chew bears equal probability of teeth encountering the foreign object, slow chewing might also reduce the chance of accidentally biting hard on the foreign object and fracturing the tooth. PMID:26462611

  1. Helicopter main-rotor speed effects: A comparison of predicted ranges of detection from the aural detection program ICHIN and the electronic detection program ARCAS

    NASA Technical Reports Server (NTRS)

    Mueller, Arnold W.; Smith, Charles D.

    1991-01-01

    NASA LaRC personnel have conducted a strudy of the predicted acoustic detection ranges associated with reduced helicopter main rotor speeds. This was accomplished by providing identical input information to both the aural detection program ICHIN 6, (I Can Hear It Now, version 6) and the electronic acoustic detection program ARCAS (Assessment of Rotorcraft Detection by Acoustics Sensing). In this study, it was concluded that reducing the main rotor speed of the helicopter by 27 percent reduced both the predicted aural and electronic detection ranges by approximately 50 percent. Additionally, ARCAS was observed to function better with narrowband spectral input than with one-third octave band spectral inputs and the predicted electronic range of acoustic detection is greater than the predicted aural detection range.

  2. Detecting Temporal Change in Dynamic Sounds: On the Role of Stimulus Duration, Speed, and Emotion

    PubMed Central

    Schirmer, Annett; Escoffier, Nicolas; Cheng, Xiaoqin; Feng, Yenju; Penney, Trevor B.

    2016-01-01

    For dynamic sounds, such as vocal expressions, duration often varies alongside speed. Compared to longer sounds, shorter sounds unfold more quickly. Here, we asked whether listeners implicitly use this confound when representing temporal regularities in their environment. In addition, we explored the role of emotions in this process. Using a mismatch negativity (MMN) paradigm, we asked participants to watch a silent movie while passively listening to a stream of task-irrelevant sounds. In Experiment 1, one surprised and one neutral vocalization were compressed and stretched to create stimuli of 378 and 600 ms duration. Stimuli were presented in four blocks, two of which used surprised and two of which used neutral expressions. In one surprised and one neutral block, short and long stimuli served as standards and deviants, respectively. In the other two blocks, the assignment of standards and deviants was reversed. We observed a climbing MMN-like negativity shortly after deviant onset, which suggests that listeners implicitly track sound speed and detect speed changes. Additionally, this MMN-like effect emerged earlier and was larger for long than short deviants, suggesting greater sensitivity to duration increments or slowing down than to decrements or speeding up. Last, deviance detection was facilitated in surprised relative to neutral blocks, indicating that emotion enhances temporal processing. Experiment 2 was comparable to Experiment 1 with the exception that sounds were spectrally rotated to remove vocal emotional content. This abolished the emotional processing benefit, but preserved the other effects. Together, these results provide insights into listener sensitivity to sound speed and raise the possibility that speed biases duration judgements implicitly in a feed-forward manner. Moreover, this bias may be amplified for duration increments relative to decrements and within an emotional relative to a neutral stimulus context. PMID:26793161

  3. Detection of changes in the fractal scaling of heart rate and speed in a marathon race

    NASA Astrophysics Data System (ADS)

    Billat, Véronique L.; Mille-Hamard, Laurence; Meyer, Yves; Wesfreid, Eva

    2009-09-01

    The aim of this study was to detect changes in the fractal scaling behavior of heart rate and speed fluctuations when the average runner’s speed decreased with fatigue. Scaling analysis in heart rate (HR) and speed (S) dynamics of marathon runners was performed using the detrended fluctuation analysis (DFA) and the wavelet based structure function. We considered both: the short-range ( α1) and the long-range ( α2) scaling exponents for the DFA method separated by a change-point, n0=64=5.3 min (box length), the same for all the races. The variability of HR and S decreased in the second part of the marathon race, while the cardiac cost time series (i.e. the number of cardiac beats per meter) increased due to the decreasing speed behavior. The scaling exponents α1 and α2 of HR and α1 of S, increased during the race ( p<0.01) as did the HR wavelet scaling exponent ( τ). These findings provide evidence of the significant effect of fatigue induced by long exercise on the heart rate and speed variability.

  4. Advancing the speed, sensitivity and accuracy of biomolecular detection using multi-length-scale engineering.

    PubMed

    Kelley, Shana O; Mirkin, Chad A; Walt, David R; Ismagilov, Rustem F; Toner, Mehmet; Sargent, Edward H

    2014-12-01

    Rapid progress in identifying disease biomarkers has increased the importance of creating high-performance detection technologies. Over the last decade, the design of many detection platforms has focused on either the nano or micro length scale. Here, we review recent strategies that combine nano- and microscale materials and devices to produce large improvements in detection sensitivity, speed and accuracy, allowing previously undetectable biomarkers to be identified in clinical samples. Microsensors that incorporate nanoscale features can now rapidly detect disease-related nucleic acids expressed in patient samples. New microdevices that separate large clinical samples into nanocompartments allow precise quantitation of analytes, and microfluidic systems that utilize nanoscale binding events can detect rare cancer cells in the bloodstream more accurately than before. These advances will lead to faster and more reliable clinical diagnostic devices. PMID:25466541

  5. Advancing the speed, sensitivity and accuracy of biomolecular detection using multi-length-scale engineering

    PubMed Central

    Kelley, Shana O.; Mirkin, Chad A.; Walt, David R.; Ismagilov, Rustem F.; Toner, Mehmet; Sargent, Edward H.

    2015-01-01

    Rapid progress in identifying disease biomarkers has increased the importance of creating high-performance detection technologies. Over the last decade, the design of many detection platforms has focused on either the nano or micro length scale. Here, we review recent strategies that combine nano- and microscale materials and devices to produce large improvements in detection sensitivity, speed and accuracy, allowing previously undetectable biomarkers to be identified in clinical samples. Microsensors that incorporate nanoscale features can now rapidly detect disease-related nucleic acids expressed in patient samples. New microdevices that separate large clinical samples into nanocompartments allow precise quantitation of analytes, and microfluidic systems that utilize nanoscale binding events can detect rare cancer cells in the bloodstream more accurately than before. These advances will lead to faster and more reliable clinical diagnostic devices. PMID:25466541

  6. Advancing the speed, sensitivity and accuracy of biomolecular detection using multi-length-scale engineering

    NASA Astrophysics Data System (ADS)

    Kelley, Shana O.; Mirkin, Chad A.; Walt, David R.; Ismagilov, Rustem F.; Toner, Mehmet; Sargent, Edward H.

    2014-12-01

    Rapid progress in identifying disease biomarkers has increased the importance of creating high-performance detection technologies. Over the last decade, the design of many detection platforms has focused on either the nano or micro length scale. Here, we review recent strategies that combine nano- and microscale materials and devices to produce large improvements in detection sensitivity, speed and accuracy, allowing previously undetectable biomarkers to be identified in clinical samples. Microsensors that incorporate nanoscale features can now rapidly detect disease-related nucleic acids expressed in patient samples. New microdevices that separate large clinical samples into nanocompartments allow precise quantitation of analytes, and microfluidic systems that utilize nanoscale binding events can detect rare cancer cells in the bloodstream more accurately than before. These advances will lead to faster and more reliable clinical diagnostic devices.

  7. Quantum witness of high-speed low-noise single-photon detection.

    PubMed

    Zhao, Lin; Huang, Kun; Liang, Yan; Chen, Jie; Shi, Xueshun; Wu, E; Zeng, Heping

    2015-12-14

    We demonstrate high-speed and low-noise near-infrared single-photon detection by using a capacitance balancing circuit to achieve a high spike noise suppression for an InGaAs/InP avalanche photodiode. The single-photon detector could operate at a tunable gate repetition rate from 10 to 60 MHz. A peak detection efficiency of 34% has been achieved with a dark count rate of 9 × 10⁻³ per gate when the detection window was set to 1 ns. Additionally, quantum detector tomography has also been performed at 60 MHz of repetition rate and for the detection window of 1 ns, enabling to witness the quantum features of the detector with the help of a negative Wigner function. By varying the bias voltage of the detector, we further demonstrated a transition from the full-quantum to semi-classical regime. PMID:26698977

  8. Face liveness detection from a single image via diffusion speed model.

    PubMed

    Wonjun Kim; Sungjoo Suh; Jae-Joon Han

    2015-08-01

    Spoofing using photographs or videos is one of the most common methods of attacking face recognition and verification systems. In this paper, we propose a real-time and nonintrusive method based on the diffusion speed of a single image to address this problem. In particular, inspired by the observation that the difference in surface properties between a live face and a fake one is efficiently revealed in the diffusion speed, we exploit antispoofing features by utilizing the total variation flow scheme. More specifically, we propose defining the local patterns of the diffusion speed, the so-called local speed patterns, as our features, which are input into the linear SVM classifier to determine whether the given face is fake or not. One important advantage of the proposed method is that, in contrast to previous approaches, it accurately identifies diverse malicious attacks regardless of the medium of the image, e.g., paper or screen. Moreover, the proposed method does not require any specific user action. Experimental results on various data sets show that the proposed method is effective for face liveness detection as compared with previous approaches proposed in studies in the literature. PMID:25879944

  9. Can the speed of sound be used for detecting critical states of fluid mixtures?

    PubMed

    Reis, João Carlos R; Ribeiro, Nuno; Aguiar-Ricardo, Ana

    2006-01-12

    The phenomenology of sound speeds in fluid mixtures is examined near and across critical lines. Using literature data for binary and ternary mixtures, it is shown that the ultrasound speed along an isotherm-isopleth passes through a minimum value in the form of an angular (or V-shaped) point at critical states. The relation between critical and pseudo-critical coordinates is discussed. For nonazeotropic fixed-composition fluid mixtures, pseudo-critical temperatures and pressures are found to be lower than the corresponding critical temperatures and pressures. The analysis shows that unstable pseudo-critical states cannot be detected using acoustic methods. The thermodynamic link between sound speeds and isochoric heat capacities is formulated and discussed in terms of p-Vm-T derivatives capable of being calculated using cubic equations of state. Based on the Griffiths-Wheeler theory of critical phenomena, a new specific link between critical sound speeds and critical isochoric heat capacities is deduced in terms of the rate of change of critical pressures and critical temperatures along the p-T projection of the critical locus of binary fluid mixtures. It is shown that the latter link can be used to obtain estimates of critical isochoric heat capacities from the experimental determination of critical speeds of sound. The applicability domain of the new link does not include binary systems at compositions along the critical line for which the rate of change in pressure with temperature changes sign. The new equation is combined with thermodynamic data to provide approximate numerical estimates for the speed of sound in two mixtures of carbon dioxide and ethane at different temperatures along their critical isochores. A clear decrease in the sound speed is found at critical points. A similar behavior is suggested by available critical heat capacity data for several binary fluid mixtures. Using an acoustic technique, the critical temperature and pressure were

  10. Time-Gated Orthogonal Scanning Automated Microscopy (OSAM) for High-speed Cell Detection and Analysis

    NASA Astrophysics Data System (ADS)

    Lu, Yiqing; Xi, Peng; Piper, James A.; Huo, Yujing; Jin, Dayong

    2012-11-01

    We report a new development of orthogonal scanning automated microscopy (OSAM) incorporating time-gated detection to locate rare-event organisms regardless of autofluorescent background. The necessity of using long-lifetime (hundreds of microseconds) luminescent biolabels for time-gated detection implies long integration (dwell) time, resulting in slow scan speed. However, here we achieve high scan speed using a new 2-step orthogonal scanning strategy to realise on-the-fly time-gated detection and precise location of 1-μm lanthanide-doped microspheres with signal-to-background ratio of 8.9. This enables analysis of a 15 mm × 15 mm slide area in only 3.3 minutes. We demonstrate that detection of only a few hundred photoelectrons within 100 μs is sufficient to distinguish a target event in a prototype system using ultraviolet LED excitation. Cytometric analysis of lanthanide labelled Giardia cysts achieved a signal-to-background ratio of two orders of magnitude. Results suggest that time-gated OSAM represents a new opportunity for high-throughput background-free biosensing applications.

  11. High speed flow cytometric detection of rare glycophorin A mutations in human blood cells

    SciTech Connect

    Langlois, R.G.; Engh, G. van den )

    1993-01-01

    The glycophorin A (GPA) assay utilizes immunofluorescent labeling and flow cytometry to measure the frequency of peripheral erythrocytes with mutant phenotypes, presumably due to mutations in erythroid precursor cells. Analysis of 5 [times] 10[sup 6] cells/assay is used to enumerate variant erythrocytes that occur at a frequency of 3-10 [times] 10[sup [minus]6] in unexposed donors. Extension of this assay to human reticulocytes requires detection of variants that occur at frequencies as low as 3 [times] 10[sup [minus]8]. The authors have used high speed data acquisition and cell classification electronics to perform 3-color analysis at rates up to 20,000 cells/s. High speed analysis of up to 10[sup 8] cells/assay has been used to enumerate GPA-variant reticulocytes in normal donors.

  12. Automated High-Speed Video Detection of Small-Scale Explosives Testing

    NASA Astrophysics Data System (ADS)

    Ford, Robert; Guymon, Clint

    2013-06-01

    Small-scale explosives sensitivity test data is used to evaluate hazards of processing, handling, transportation, and storage of energetic materials. Accurate test data is critical to implementation of engineering and administrative controls for personnel safety and asset protection. Operator mischaracterization of reactions during testing contributes to either excessive or inadequate safety protocols. Use of equipment and associated algorithms to aid the operator in reaction determination can significantly reduce operator error. Safety Management Services, Inc. has developed an algorithm to evaluate high-speed video images of sparks from an ESD (Electrostatic Discharge) machine to automatically determine whether or not a reaction has taken place. The algorithm with the high-speed camera is termed GoDetect (patent pending). An operator assisted version for friction and impact testing has also been developed where software is used to quickly process and store video of sensitivity testing. We have used this method for sensitivity testing with multiple pieces of equipment. We present the fundamentals of GoDetect and compare it to other methods used for reaction detection.

  13. Bio-inspired materials for electrochemical devices

    NASA Astrophysics Data System (ADS)

    Pawlicka, A.; Firmino, A.; Sentanin, F.; Sabadini, R. C.; Jimenez, D. E. Q.; Jayme, C. C.; Mindroiu, M.; Zgarian, R. G.; Tihan, G. T.; Rau, I.; Silva, M. M.; Nogueira, A. F.; Kanicki, J.; Kajzar, F.

    2015-10-01

    Natural macromolecules are very promising row materials to be used in modern technology including security and defense. They are abundant in nature, easy to extract and possess biocompatibility and biodegradability properties. These materials can be modified throughout chemical or physical processes, and can be doped with lithium and rare earth salts, ionic liquids, organic and inorganic acids. In this communication samples of DNA and modified DNA were doped with Prussian Blue (PB), poly(ethylene dioxythiophene) (PEDOT), europium and erbium triflate and organic dyes such as Nile Blue (NB), Disperse Red 1 (DR1) and Disperse Orange 3 (DO3). The colored or colorless membranes were characterized by electrochemical and spectroscopic measurements, and they were applied in electrochromic devices (ECDs) and dye sensitized solar cells (DSSC). ECDs change the color under applied potential, so they can modulate the intensity of transmitted light of 15 to 35%. As the electrochromic materials, WO3 or Prussian blue (PB), are usually blue colored, the color change is from transparent to blue. DNA, and the complexes: DNA-CTMA, DNA-DODA and DNAPEDOT: PSS were also investigated as either hole carrier material (HTM) or polymer electrolyte in dye-sensitized solar cells (DSSC). The DNA-based samples as HTM in small DSSCs revealed a solar energy conversion efficiency of 0.56%. Polymer electrolytes of DNA-CTMA and DNA-DODA, both with 10 wt% of LiI/I2, applied in small DSSC, exhibited the efficiencies of 0.18 and 0.66%, respectively. The obtained results show that natural macromolecules-based membranes are not only environmentally friendly but are also promising materials to be investigated for several electrochemical devices. However, to obtain better performances more research is still needed.

  14. Bio-inspired color image enhancement

    NASA Astrophysics Data System (ADS)

    Meylan, Laurence; Susstrunk, Sabine

    2004-06-01

    Capturing and rendering an image that fulfills the observer's expectations is a difficult task. This is due to the fact that the signal reaching the eye is processed by a complex mechanism before forming a percept, whereas a capturing device only retains the physical value of light intensities. It is especially difficult to render complex scenes with highly varying luminances. For example, a picture taken inside a room where objects are visible through the windows will not be rendered correctly by a global technique. Either details in the dim room will be hidden in shadow or the objects viewed through the window will be too bright. The image has to be treated locally to resemble more closely to what the observer remembers. The purpose of this work is to develop a technique for rendering images based on human local adaptation. We take inspiration from a model of color vision called Retinex. This model determines the perceived color given spatial relationships of the captured signals. Retinex has been used as a computational model for image rendering. In this article, we propose a new solution inspired by Retinex that is based on a single filter applied to the luminance channel. All parameters are image-dependent so that the process requires no parameter tuning. That makes the method more flexible than other existing ones. The presented results show that our method suitably enhances high dynamic range images.

  15. Slow Movements of Bio-Inspired Limbs

    NASA Astrophysics Data System (ADS)

    Babikian, Sarine; Valero-Cuevas, Francisco J.; Kanso, Eva

    2016-05-01

    Slow and accurate finger and limb movements are essential to daily activities, but the underlying mechanics is relatively unexplored. Here, we develop a mathematical framework to examine slow movements of tendon-driven limbs that are produced by modulating the tendons' stiffness parameters. Slow limb movements are driftless in the sense that movement stops when actuations stop. We demonstrate, in the context of a planar tendon-driven system representing a finger, that the control of stiffness suffices to produce stable and accurate limb postures and quasi-static (slow) transitions among them. We prove, however, that stable postures are achievable only when tendons are pretensioned, i.e., they cannot become slack. Our results further indicate that a non-smoothness in slow movements arises because the precision with which individual stiffnesses need to be altered changes substantially throughout the limb's motion.

  16. Bio-inspired impact-resistant composites.

    PubMed

    Grunenfelder, L K; Suksangpanya, N; Salinas, C; Milliron, G; Yaraghi, N; Herrera, S; Evans-Lutterodt, K; Nutt, S R; Zavattieri, P; Kisailus, D

    2014-09-01

    Through evolutionary processes, biological composites have been optimized to fulfil specific functions. This optimization is exemplified in the mineralized dactyl club of the smashing predator stomatopod (specifically, Odontodactylus scyllarus). This crustacean's club has been designed to withstand the thousands of high-velocity blows that it delivers to its prey. The endocuticle of this multiregional structure is characterized by a helicoidal arrangement of mineralized fiber layers, an architecture which results in impact resistance and energy absorbance. Here, we apply the helicoidal design strategy observed in the stomatopod club to the fabrication of high-performance carbon fiber-epoxy composites. Through experimental and computational methods, a helicoidal architecture is shown to reduce through-thickness damage propagation in a composite panel during an impact event and result in an increase in toughness. These findings have implications in the design of composite parts for aerospace, automotive and armor applications. PMID:24681369

  17. Bio-inspired Hybrid Carbon Nanotube Muscles.

    PubMed

    Kim, Tae Hyeob; Kwon, Cheong Hoon; Lee, Changsun; An, Jieun; Phuong, Tam Thi Thanh; Park, Sun Hwa; Lima, Márcio D; Baughman, Ray H; Kang, Tong Mook; Kim, Seon Jeong

    2016-01-01

    There has been continuous progress in the development for biomedical engineering systems of hybrid muscle generated by combining skeletal muscle and artificial structure. The main factor affecting the actuation performance of hybrid muscle relies on the compatibility between living cells and their muscle scaffolds during cell culture. Here, we developed a hybrid muscle powered by C2C12 skeletal muscle cells based on the functionalized multi-walled carbon nanotubes (MWCNT) sheets coated with poly(3,4-ethylenedioxythiophene) (PEDOT) to achieve biomimetic actuation. This hydrophilic hybrid muscle is physically durable in solution and responds to electric field stimulation with flexible movement. Furthermore, the biomimetic actuation when controlled by electric field stimulation results in movement similar to that of the hornworm by patterned cell culture method. The contraction and relaxation behavior of the PEDOT/MWCNT-based hybrid muscle is similar to that of the single myotube movement, but has faster relaxation kinetics because of the shape-maintenance properties of the freestanding PEDOT/MWCNT sheets in solution. Our development provides the potential possibility for substantial innovation in the next generation of cell-based biohybrid microsystems. PMID:27220918

  18. Bio-inspired hemispherical compound eye camera

    NASA Astrophysics Data System (ADS)

    Xiao, Jianliang; Song, Young Min; Xie, Yizhu; Malyarchuk, Viktor; Jung, Inhwa; Choi, Ki-Joong; Liu, Zhuangjian; Park, Hyunsung; Lu, Chaofeng; Kim, Rak-Hwan; Li, Rui; Crozier, Kenneth B.; Huang, Yonggang; Rogers, John A.

    2014-03-01

    Compound eyes in arthropods demonstrate distinct imaging characteristics from human eyes, with wide angle field of view, low aberrations, high acuity to motion and infinite depth of field. Artificial imaging systems with similar geometries and properties are of great interest for many applications. However, the challenges in building such systems with hemispherical, compound apposition layouts cannot be met through established planar sensor technologies and conventional optics. We present our recent progress in combining optics, materials, mechanics and integration schemes to build fully functional artificial compound eye cameras. Nearly full hemispherical shapes (about 160 degrees) with densely packed artificial ommatidia were realized. The number of ommatidia (180) is comparable to those of the eyes of fire ants and bark beetles. The devices combine elastomeric compound optical elements with deformable arrays of thin silicon photodetectors, which were fabricated in the planar geometries and then integrated and elastically transformed to hemispherical shapes. Imaging results and quantitative ray-tracing-based simulations illustrate key features of operation. These general strategies seem to be applicable to other compound eye devices, such as those inspired by moths and lacewings (refracting superposition eyes), lobster and shrimp (reflecting superposition eyes), and houseflies (neural superposition eyes).

  19. Bio-inspired Artificial Apposition Compound Eye

    NASA Astrophysics Data System (ADS)

    Xiao, Jianliang; Song, Youngmin; Xie, Yizhu; Malyarchuk, Viktor; Huang, Yonggang; Rogers, John

    2014-03-01

    In arthropods, evolution has created a remarkably sophisticated class of imaging system, with wide angle field of view, low aberrations, high acuity to motion and infinite depth of field. A challenge in building digital cameras with the hemispherical, compound apposition layouts of arthropod eyes is that essential design requirements cannot be met with existing planar sensor technologies or conventional optics. We present ideas in materials, mechanics and integration schemes that enable scalable pathways to working, arthropod-inspired cameras in nearly full hemispherical shapes with surfaces densely populated by imaging elements (i.e. artificial ommatidia). The devices combine elastomeric compound optical elements with deformable arrays of thin silicon photodetectors, in co-integrated sheets that can be elastically transformed from the planar geometries in which they are fabricated, to hemispherical shapes for integration into apposition cameras. Experimental and theoretical studies reveal key aspects of the materials science and physics of these systems. Imaging results and quantitative ray-tracing based modeling illustrate essential features of their operation.

  20. Bio-inspired unmanned undersea vehicle

    NASA Astrophysics Data System (ADS)

    Smith, Colin F.; Priya, Shashank

    2010-04-01

    Biological systems in ocean environment provide all the desired features required for design of unmanned undersea vehicles. We noticed the uniqueness and simplicity in the design of rowing medusa and have successfully demonstrated working prototypes of Aurelia Aurita. In this study, we demonstrate the effect of bell joints in reducing the contraction force required for deformation. The study is based on observations made for the sub-umbrella features of jellyfish. Artificial jellyfish unmanned undersea vehicle (UUV) was fabricated consisting of silicone as the matrix material and shape memory alloy (SMA) as the actuation material. UUV was characterized for its performance and tailored to achieve vertical motion. SMAs were selected for actuation material because they are simple current-driven device providing large strain and blocking force. However, electrical power requirements were found to be quite high in the underwater conditions. It was identified that by including "joints" in the structural material forming the bell, the overall power requirement can be reduced as it lowers the resistance to compression. An analytical model was developed that correlates the deformation achieved with the morphology of the joints. Experiments were conducted to characterize the effect of both joint shapes and structural materials on the motion. Results are compared with that of natural medusa gastrodermal lamella and analyzed using the theoretical model. By including the features inherently present in natural jellyfish, the required compression force was found to be decreased.

  1. Bio-inspired Hybrid Carbon Nanotube Muscles

    NASA Astrophysics Data System (ADS)

    Kim, Tae Hyeob; Kwon, Cheong Hoon; Lee, Changsun; An, Jieun; Phuong, Tam Thi Thanh; Park, Sun Hwa; Lima, Márcio D.; Baughman, Ray H.; Kang, Tong Mook; Kim, Seon Jeong

    2016-05-01

    There has been continuous progress in the development for biomedical engineering systems of hybrid muscle generated by combining skeletal muscle and artificial structure. The main factor affecting the actuation performance of hybrid muscle relies on the compatibility between living cells and their muscle scaffolds during cell culture. Here, we developed a hybrid muscle powered by C2C12 skeletal muscle cells based on the functionalized multi-walled carbon nanotubes (MWCNT) sheets coated with poly(3,4-ethylenedioxythiophene) (PEDOT) to achieve biomimetic actuation. This hydrophilic hybrid muscle is physically durable in solution and responds to electric field stimulation with flexible movement. Furthermore, the biomimetic actuation when controlled by electric field stimulation results in movement similar to that of the hornworm by patterned cell culture method. The contraction and relaxation behavior of the PEDOT/MWCNT-based hybrid muscle is similar to that of the single myotube movement, but has faster relaxation kinetics because of the shape-maintenance properties of the freestanding PEDOT/MWCNT sheets in solution. Our development provides the potential possibility for substantial innovation in the next generation of cell-based biohybrid microsystems.

  2. Bio-inspired Hybrid Carbon Nanotube Muscles

    PubMed Central

    Kim, Tae Hyeob; Kwon, Cheong Hoon; Lee, Changsun; An, Jieun; Phuong, Tam Thi Thanh; Park, Sun Hwa; Lima, Márcio D.; Baughman, Ray H.; Kang, Tong Mook; Kim, Seon Jeong

    2016-01-01

    There has been continuous progress in the development for biomedical engineering systems of hybrid muscle generated by combining skeletal muscle and artificial structure. The main factor affecting the actuation performance of hybrid muscle relies on the compatibility between living cells and their muscle scaffolds during cell culture. Here, we developed a hybrid muscle powered by C2C12 skeletal muscle cells based on the functionalized multi-walled carbon nanotubes (MWCNT) sheets coated with poly(3,4-ethylenedioxythiophene) (PEDOT) to achieve biomimetic actuation. This hydrophilic hybrid muscle is physically durable in solution and responds to electric field stimulation with flexible movement. Furthermore, the biomimetic actuation when controlled by electric field stimulation results in movement similar to that of the hornworm by patterned cell culture method. The contraction and relaxation behavior of the PEDOT/MWCNT-based hybrid muscle is similar to that of the single myotube movement, but has faster relaxation kinetics because of the shape-maintenance properties of the freestanding PEDOT/MWCNT sheets in solution. Our development provides the potential possibility for substantial innovation in the next generation of cell-based biohybrid microsystems. PMID:27220918

  3. Bio-inspired nano tools for neuroscience.

    PubMed

    Das, Suradip; Carnicer-Lombarte, Alejandro; Fawcett, James W; Bora, Utpal

    2016-07-01

    Research and treatment in the nervous system is challenged by many physiological barriers posing a major hurdle for neurologists. The CNS is protected by a formidable blood brain barrier (BBB) which limits surgical, therapeutic and diagnostic interventions. The hostile environment created by reactive astrocytes in the CNS along with the limited regeneration capacity of the PNS makes functional recovery after tissue damage difficult and inefficient. Nanomaterials have the unique ability to interface with neural tissue in the nano-scale and are capable of influencing the function of a single neuron. The ability of nanoparticles to transcend the BBB through surface modifications has been exploited in various neuro-imaging techniques and for targeted drug delivery. The tunable topography of nanofibers provides accurate spatio-temporal guidance to regenerating axons. This review is an attempt to comprehend the progress in understanding the obstacles posed by the complex physiology of the nervous system and the innovations in design and fabrication of advanced nanomaterials drawing inspiration from natural phenomenon. We also discuss the development of nanomaterials for use in Neuro-diagnostics, Neuro-therapy and the fabrication of advanced nano-devices for use in opto-electronic and ultrasensitive electrophysiological applications. The energy efficient and parallel computing ability of the human brain has inspired the design of advanced nanotechnology based computational systems. However, extensive use of nanomaterials in neuroscience also raises serious toxicity issues as well as ethical concerns regarding nano implants in the brain. In conclusion we summarize these challenges and provide an insight into the huge potential of nanotechnology platforms in neuroscience. PMID:27107796

  4. Bio-inspired tactile sensing arrays

    NASA Astrophysics Data System (ADS)

    Dahiya, Ravinder S.; Valle, Maurizio; Metta, Giorgio; Lorenzelli, Leandro

    2009-05-01

    This work presents the development of tactile sensing arrays, inspired by cutaneous sensing in humans, for the fingertips of a humanoid robot. The tactile sensing arrays have been developed in two phases. Microelectrode arrays (MEA), having 32 sensing elements - each epoxy adhered with 25μm thick piezoelectric polymer (PVDF-TrFE) film, were fabricated in the first phase. When connected to the gate of FET devices (external to the chip), each element on MEA acts like an extended gate; thereby facilitating modulation of charge in the induced channel by the charge generated in PVDF-TrFE film - as a result of applied force. Thus, each sensing element converts force into voltage. The tactile sensing arrays developed in second phase work on the same principle but are free from any extended gate. These arrays (having 25 sensing elements) use POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistors) touch sensing elements - in which, piezoelectric polymer film is directly spin coated on the gate area of the FET devices. Thus, a POSFET touch sensing element 'senses and partially processes at same site' - as is done by receptors in human skin. The spatial-temporal performance of these chips is similar to that of skin in the human fingertips.

  5. Bio-inspired Computing for Robots

    NASA Technical Reports Server (NTRS)

    Laufenberg, Larry

    2003-01-01

    Living creatures may provide algorithms to enable active sensing/control systems in robots. Active sensing could enable planetary rovers to feel their way in unknown environments. The surface of Jupiter's moon Europa consists of fractured ice over a liquid sea that may contain microbes similar to those on Earth. To explore such extreme environments, NASA needs robots that autonomously survive, navigate, and gather scientific data. They will be too far away for guidance from Earth. They must sense their environment and control their own movements to avoid obstacles or investigate a science opportunity. To meet this challenge, CICT's Information Technology Strategic Research (ITSR) Project is funding neurobiologists at NASA's Jet Propulsion Laboratory (JPL) and selected universities to search for biologically inspired algorithms that enable robust active sensing and control for exploratory robots. Sources for these algorithms are living creatures, including rats and electric fish.

  6. Bio-inspired organic field effect transistors

    NASA Astrophysics Data System (ADS)

    Irimia-Vladu, Mihai; Troshin, Pavel A.; Schwabegger, Günther; Bodea, Marius; Schwödiauer, Reinhard; Fergus, Jeffrey W.; Razumov, Vladimir; Bauer, Siegfried; Sariciftci, Niyazi Serdar

    2010-08-01

    Two major concerns in the world nowadays are the plastic consumption and waste. Because to the economic growth and the incessant demand of plastics in developing countries, plastics consumption is projected to increase by a factor of two to three during the actual decade1. As an intuitive example, the amount of municipal solid waste (estimated per person per year) averages ~440 kg for China, ~550 kg for the European Union and ~790 kg for the United States, with almost 50% of the waste being electronic products and plastics1,2. Green technology based on biodegradable/compostable materials is perceived as an ultimate goal for solving waste problems. Currently there are numerous efforts for producing compostable plastic materials for applications in daily life products, such as plastic bags and disposable dishware. When such low-end products are fabricated with compostable materials, electronics included in such goods should be also based on materials that are easily compostable.

  7. A digital TV system for the detection of high speed human motion

    NASA Astrophysics Data System (ADS)

    Fang, R. C.

    1981-08-01

    Two array cameras and a force plate were linked to a PDP-11/34 minicomputer for an on-line recording of high speed human motion. A microprocessor-based interface system was constructed to allow preprocessing and coordinating of the video data before being transferred to the minicomputer. Control programs of the interface system are stored in the disk and loaded into the program storage areas of the microprocessor before the interface system starts its operation. Software programs for collecting and processing video and force data have been written. Experiments on the detection of human jumping have been carried out. Normal gait and amputee gait have also been recorded and analyzed.

  8. Infrared thermography for detection of laminar-turbulent transition in low-speed wind tunnel testing

    NASA Astrophysics Data System (ADS)

    Joseph, Liselle A.; Borgoltz, Aurelien; Devenport, William

    2016-05-01

    This work presents the details of a system for experimentally identifying laminar-to-turbulent transition using infrared thermography applied to large, metal models in low-speed wind tunnel tests. Key elements of the transition detection system include infrared cameras with sensitivity in the 7.5- to 14.0-µm spectral range and a thin, insulating coat for the model. The fidelity of the system was validated through experiments on two wind-turbine blade airfoil sections tested at Reynolds numbers between Re = 1.5 × 106 and 3 × 106. Results compare well with measurements from surface pressure distributions and stethoscope observations. However, the infrared-based system provides data over a much broader range of conditions and locations on the model. This paper chronicles the design, implementation and validation of the infrared transition detection system, a subject which has not been widely detailed in the literature to date.

  9. Research on the filtering algorithm in speed and position detection of maglev trains.

    PubMed

    Dai, Chunhui; Long, Zhiqiang; Xie, Yunde; Xue, Song

    2011-01-01

    This paper introduces in brief the traction system of a permanent magnet electrodynamic suspension (EDS) train. The synchronous traction mode based on long stators and track cable is described. A speed and position detection system is recommended. It is installed on board and is used as the feedback end. Restricted by the maglev train's structure, the permanent magnet electrodynamic suspension (EDS) train uses the non-contact method to detect its position. Because of the shake and the track joints, the position signal sent by the position sensor is always aberrant and noisy. To solve this problem, a linear discrete track-differentiator filtering algorithm is proposed. The filtering characters of the track-differentiator (TD) and track-differentiator group are analyzed. The four series of TD are used in the signal processing unit. The result shows that the track-differentiator could have a good effect and make the traction system run normally. PMID:22164012

  10. Research on the Filtering Algorithm in Speed and Position Detection of Maglev Trains

    PubMed Central

    Dai, Chunhui; Long, Zhiqiang; Xie, Yunde; Xue, Song

    2011-01-01

    This paper introduces in brief the traction system of a permanent magnet electrodynamic suspension (EDS) train. The synchronous traction mode based on long stators and track cable is described. A speed and position detection system is recommended. It is installed on board and is used as the feedback end. Restricted by the maglev train’s structure, the permanent magnet electrodynamic suspension (EDS) train uses the non-contact method to detect its position. Because of the shake and the track joints, the position signal sent by the position sensor is always aberrant and noisy. To solve this problem, a linear discrete track-differentiator filtering algorithm is proposed. The filtering characters of the track-differentiator (TD) and track-differentiator group are analyzed. The four series of TD are used in the signal processing unit. The result shows that the track-differentiator could have a good effect and make the traction system run normally. PMID:22164012

  11. High-speed atomic force microscope based on an astigmatic detection system

    SciTech Connect

    Liao, H.-S.; Chen, Y.-H.; Hwu, E.-T.; Chang, C.-S.; Hwang, I.-S.; Ding, R.-F.; Huang, H.-F.; Wang, W.-M.; Huang, K.-Y.

    2014-10-15

    High-speed atomic force microscopy (HS-AFM) enables visualizing dynamic behaviors of biological molecules under physiological conditions at a temporal resolution of 1s or shorter. A small cantilever with a high resonance frequency is crucial in increasing the scan speed. However, detecting mechanical resonances of small cantilevers is technically challenging. In this study, we constructed an atomic force microscope using a digital versatile disc (DVD) pickup head to detect cantilever deflections. In addition, a flexure-guided scanner and a sinusoidal scan method were implemented. In this work, we imaged a grating sample in air by using a regular cantilever and a small cantilever with a resonance frequency of 5.5 MHz. Poor tracking was seen at the scan rate of 50 line/s when a cantilever for regular AFM imaging was used. Using a small cantilever at the scan rate of 100 line/s revealed no significant degradation in the topographic images. The results indicate that a smaller cantilever can achieve a higher scan rate and superior force sensitivity. This work shows the potential for using a DVD pickup head in future HS-AFM technology.

  12. Recognition Stage for a Speed Supervisor Based on Road Sign Detection

    PubMed Central

    Carrasco, Juan-Pablo; de la Escalera, Arturo; Armingol, José María

    2012-01-01

    Traffic accidents are still one of the main health problems in the World. A number of measures have been applied in order to reduce the number of injuries and fatalities in roads, i.e., implementation of Advanced Driver Assistance Systems (ADAS) based on image processing. In this paper, a real time speed supervisor based on road sign recognition that can work both in urban and non-urban environments is presented. The system is able to recognize 135 road signs, belonging to the danger, yield, prohibition obligation and indication types, and sends warning messages to the driver upon the combination of two pieces of information: the current speed of the car and the road sign symbol. The core of this paper is the comparison between the two main methods which have been traditionally used for detection and recognition of road signs: template matching (TM) and neural networks (NN). The advantages and disadvantages of the two approaches will be shown and commented. Additionally we will show how the use of well-known algorithms to avoid illumination issues reduces the amount of images needed to train a neural network.

  13. Rotating Pip Detection and Stall Warning in High-Speed Compressors Using Structure Function

    NASA Technical Reports Server (NTRS)

    Bright, Michelle M.; Qammar, Helen; Vhora, Hanif; Schaffer, Michael

    1999-01-01

    A statistic for both rotating pip and incipient stall detection, called Structure Function is introduced for use in high speed research compressor environments. Experimental studies on stall inception processes have long observed two types of pre-stall compressor activity. Presently there exist methods for indicating modal stall precursive events in the compressor. This is a first application of a new method to detect rotating pip activity prior to stall in research compressors. The algorithm requires a very short sample of data to distinguish pip activity prior to stall, and thus may be used in a real time application. Additionally, this Structure Function algorithm is also used as a single sensor stall warning method under a variety of operating conditions, including clean inlet conditions, radially and circumferentially distorted inlet conditions, and in examples of steady air injection along the casing, and controlled air injection conditions. Structure Function provides a potential advantage over linear spectral techniques and wavelet algorithms for stall detection due to the simplicity of the algorithm and because it does not rely on a priori knowledge of frequency content.

  14. Supercontinuum high-speed cavity-enhanced absorption spectroscopy for sensitive multispecies detection.

    PubMed

    Werblinski, Thomas; Lämmlein, Bastian; Huber, Franz J T; Zigan, Lars; Will, Stefan

    2016-05-15

    Cavity-enhanced absorption spectroscopy is promising for many applications requiring a very high concentration sensitivity but often accompanied by low temporal resolution. In this Letter, we demonstrate a broadband cavity-enhanced absorption spectrometer capable of detection rates of up to 50 kHz, based on a spatially coherent supercontinuum (SC) light source and an in-house-built, high-speed near-infrared spectrograph. The SC spectrometer allows for the simultaneous quantitative detection of CO2, C2H2, and H2O within a spectral range from 1420 to 1570 nm. Using cavity mirrors with a specified reflectivity of R=98.0±0.3% a minimal spectrally averaged absorption coefficient of αmin=1·10-5  cm-1 can be detected at a repetition rate of 50 kHz. PMID:27176993

  15. High speed QPPM direct detection optical communication receivers for FSDD intersatellite links

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic M.; Sun, Xiaoli

    1993-01-01

    This final report consists of four separate reports, one for each project involved in this contract. The first report is entitled '325 Mbps QPPM (quaternary pulse position modulation) Direct Detection Free Space Optical Communication Encoder and Receiver,' which was our primary work. The second report is entitled 'Test Results of the 325 Mbps QPPM High Speed Data Transmission GaAs ASICs,' which describes our work in connection with Galaxy Microsystems, Inc. who produced these ASICs for NASA. The third report, 'Receiver Performance Analysis of BPPM Optical Communication Systems Using 1.3 micron Wavelength Transmitter and InGaAs PIN Photodiodes,' was prepared at the request of the NASA/Photonics Branch for their efforts in upgrading the 1773 optical fiber data bus. The fourth report, 'Photomultiplier Tubes for Use at 1.064 micron Wavelength,' was also prepared at the request of the NASA/Photonics Branch as a research project.

  16. COMPASS server for homology detection: improved statistical accuracy, speed and functionality

    PubMed Central

    Sadreyev, Ruslan I.; Tang, Ming; Kim, Bong-Hyun; Grishin, Nick V.

    2009-01-01

    COMPASS is a profile-based method for the detection of remote sequence similarity and the prediction of protein structure. Here we describe a recently improved public web server of COMPASS, http://prodata.swmed.edu/compass. The server features three major developments: (i) improved statistical accuracy; (ii) increased speed from parallel implementation; and (iii) new functional features facilitating structure prediction. These features include visualization tools that allow the user to quickly and effectively analyze specific local structural region predictions suggested by COMPASS alignments. As an application example, we describe the structural, evolutionary and functional analysis of a protein with unknown function that served as a target in the recent CASP8 (Critical Assessment of Techniques for Protein Structure Prediction round 8). URL: http://prodata.swmed.edu/compass PMID:19435884

  17. COMPASS server for homology detection: improved statistical accuracy, speed and functionality.

    PubMed

    Sadreyev, Ruslan I; Tang, Ming; Kim, Bong-Hyun; Grishin, Nick V

    2009-07-01

    COMPASS is a profile-based method for the detection of remote sequence similarity and the prediction of protein structure. Here we describe a recently improved public web server of COMPASS, http://prodata.swmed.edu/compass. The server features three major developments: (i) improved statistical accuracy; (ii) increased speed from parallel implementation; and (iii) new functional features facilitating structure prediction. These features include visualization tools that allow the user to quickly and effectively analyze specific local structural region predictions suggested by COMPASS alignments. As an application example, we describe the structural, evolutionary and functional analysis of a protein with unknown function that served as a target in the recent CASP8 (Critical Assessment of Techniques for Protein Structure Prediction round 8). URL: http://prodata.swmed.edu/compass. PMID:19435884

  18. Electromagnetic Field Analysis and Modeling of a Relative Position Detection Sensor for High Speed Maglev Trains

    PubMed Central

    Xue, Song; He, Ning; Long, Zhiqiang

    2012-01-01

    The long stator track for high speed maglev trains has a tooth-slot structure. The sensor obtains precise relative position information for the traction system by detecting the long stator tooth-slot structure based on nondestructive detection technology. The magnetic field modeling of the sensor is a typical three-dimensional (3-D) electromagnetic problem with complex boundary conditions, and is studied semi-analytically in this paper. A second-order vector potential (SOVP) is introduced to simplify the vector field problem to a scalar field one, the solution of which can be expressed in terms of series expansions according to Multipole Theory (MT) and the New Equivalent Source (NES) method. The coefficients of the expansions are determined by the least squares method based on the boundary conditions. Then, the solution is compared to the simulation result through Finite Element Analysis (FEA). The comparison results show that the semi-analytical solution agrees approximately with the numerical solution. Finally, based on electromagnetic modeling, a difference coil structure is designed to improve the sensitivity and accuracy of the sensor. PMID:22778652

  19. Electromagnetic field analysis and modeling of a relative position detection sensor for high speed maglev trains.

    PubMed

    Xue, Song; He, Ning; Long, Zhiqiang

    2012-01-01

    The long stator track for high speed maglev trains has a tooth-slot structure. The sensor obtains precise relative position information for the traction system by detecting the long stator tooth-slot structure based on nondestructive detection technology. The magnetic field modeling of the sensor is a typical three-dimensional (3-D) electromagnetic problem with complex boundary conditions, and is studied semi-analytically in this paper. A second-order vector potential (SOVP) is introduced to simplify the vector field problem to a scalar field one, the solution of which can be expressed in terms of series expansions according to Multipole Theory (MT) and the New Equivalent Source (NES) method. The coefficients of the expansions are determined by the least squares method based on the boundary conditions. Then, the solution is compared to the simulation result through Finite Element Analysis (FEA). The comparison results show that the semi-analytical solution agrees approximately with the numerical solution. Finally, based on electromagnetic modeling, a difference coil structure is designed to improve the sensitivity and accuracy of the sensor. PMID:22778652

  20. Underwater Ambient Noise and Sperm Whale Click Detection during Extreme Wind Speed Conditions

    NASA Astrophysics Data System (ADS)

    Newcomb, Joal J.; Wright, Andrew J.; Kuczaj, Stan; Thames, Rachel; Hillstrom, Wesley R.; Goodman, Ralph

    2004-11-01

    The Littoral Acoustic Demonstration Center (LA DC) deployed three Environmental Acoustic Recording System (EARS) buoys in the northern Gulf of Mexico during the summers of 2001 (LADC 01) and 2002 (LADC 02). The hydrophone of each buoy was approximately 50m from the bottom in water depths of 645m to 1034m. During LADC 01 Tropical Storm Barry passed within 93nmi east of the EARS buoys. During LADC 02 Tropical Storm Isidore and Hurricane Lili passed within approximately 73nmi and 116nmi, respectively, west of the EARS buoys. The proximity of these storm systems to the EARS buoys, in conjunction with wind speed data from three nearby NDBC weather buoys, allows for the direct comparison of underwater ambient noise levels with high wind speeds. These results are compared to the G. M. Wenz spectra at frequencies from 1kHz to 5.5kHz. In addition, the impact of storm conditions on sperm whale clicks was assessed. In particular, although the time period during the closest approach of TS Barry tended to produce lower click rates, this time period did not have the greatest incidence of non-detection at all the EARS buoys. It follows that storm-related masking noise could not have been responsible for all the observed trends. The data suggest that sperm whales may have left the vicinity of the deepest EARS buoy (nearest TS Barry's storm track) during the storm and possibly moved into the shallower waters around the other EARS buoys. It also appears that sperm whales may not have returned to the deepest EARS area, or did not resume normal behavior immediately after the storm, as the click rate did not recover to pre-storm levels during the period after TS Barry had dissipated. Results of these analyses and the ambient noise analysis will be presented. (Research supported by ONR).

  1. Pump Speed Waveform Analysis to Detect Aortic Valve Opening in Patients on Ventricular Assist Device Support.

    PubMed

    Hayward, Christopher; Lim, Choon Pin; Schima, Heinrich; Macdonald, Peter; Moscato, Francesco; Muthiah, Kavitha; Granegger, Marcus

    2015-08-01

    As the aortic valve (AV) opens, the pump pressure head remains constant, which is reflected as a "notch/plateau" in pump pressure and flow signals. However, instantaneous flow estimation may be influenced by friction and is particularly difficult in axial pumps. Therefore, a new method to determine the duration of AV opening based on the area under the curve (AUC) of the power spectral density analysis of pump speed signal was developed. Data from patients implanted with HeartWare HVAD left ventricular assist device were studied at different pump speeds, with simultaneous transthoracic echocardiography in two cohorts. In the first group, pump data of 15 patients were used to investigate the ability to discriminate between an open and closed AV. In the second cohort of a further 13 patients, the duration of AV opening was measured from digitized M-mode images, and the relationship between the AV opening time and the new method assessed. In 14 of the initial 15 patients, AV status could be discriminated using only one threshold for all patients. In the second cohort, gradual speed reduction resulted in aortic valve opening in 12 of the 13 patients. The correlation between AV opening duration and AUC was 0.96 ± 0.03. Regression analysis indicated a linear relationship in each of the patients with a small error between the fit and the measured opening time (root mean square error = 11.0 ± 7.6 ms). However, the slopes (69.0 ± 52.8) and intercepts (-31.4 ± 78.0) varied widely between patients. The sensitivity and specificity for the new method using AUC threshold of 0.95 for aortic valve closure was 95% and 91%, respectively. The newly developed method to detect AV opening not only provides information on the AV status during LVAD support (open/closed) but also gives insight into the duration of AV opening. Because the slope of the relationship varies from patient to patient, initial training and adaptation of the method to each patient seems to

  2. High-Speed Digital Signal Processing Method for Detection of Repeating Earthquakes Using GPGPU-Acceleration

    NASA Astrophysics Data System (ADS)

    Kawakami, Taiki; Okubo, Kan; Uchida, Naoki; Takeuchi, Nobunao; Matsuzawa, Toru

    2013-04-01

    detailed analysis of repeating earthquakes. This method gives us the correlation between two seismic data at each frequency. Then, we evaluate the effectiveness of these methods. Moreover, we also examined the GPGPU acceleration technique for these methods. We compare the execution time between GPU (NVIDIA GeForce GTX 580) and CPU (Intel Core i7 960) processing. The parameters of both analyses are on equal terms. In case of band limited phase only correlation, the obtained results indicate that single GPU is ca. 8.0 times faster than 4-core CPU (auto-optimization with OpenMP). On the other hand, GPU is times as fast as CPU. And in case of coherence function using three components, GPU is 12.7 times as fast as CPU. This study examines the high-speed signal processing of huge seismic data using the GPU architecture. It was found that both band-limited Fourier phase correlation and coherence function using three orthogonal components are effective, and that the GPGPU-based acceleration for the temporal signal processing is very useful. We will employ the multi-GPU computing, and expand the GPGPU-based high-speed signal processing framework for the detection of repeating earthquakes in the future.

  3. Dual-detection confocal microscopy: high-speed surface profiling without depth scanning

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Ryoung; Gweon, Dae-Gab; Yoo, Hongki

    2016-03-01

    We propose a new method for three-dimensional (3-D) imaging without depth scanning that we refer to as the dual-detection confocal microscopy (DDCM). Compared to conventional confocal microscopy, DDCM utilizes two pinholes of different sizes. DDCM generates two axial response curves which have different stiffness according to the pinhole diameters. The two axial response curves can draw the characteristics curve of the system which shows the relationship between the axial position of the sample and the intensity ratio. Utilizing the characteristic curve, the DDCM reconstructs a 3-D surface profile with a single 2-D scanning. The height of each pixel is calculated by the intensity ratio of the pixel and the intensity ratio curve. Since the height information can be obtained directly from the characteristic curve without depth scanning, a major advantage of DDCM over the conventional confocal microscopy is a speed. The 3-D surface profiling time is dramatically reduced. Furthermore, DDCM can measure 3-D images without the influence of the sample condition since the intensity ratio is independent of the quantum yield and reflectance. We present two types of DDCM, such as a fluorescence microscopy and a reflectance microscopy. In addition, we extend the measurement range axially by varying the pupil function. Here, we demonstrate the working principle of DDCM and the feasibility of the proposed methods.

  4. Integrated Scalable Parallel Firewall and Intrusion Detection System for High-Speed Networks

    SciTech Connect

    Fulp, Errin W; Anderson, Robert E; Ahn, David K

    2009-08-31

    This project developed a new scalable network firewall and Intrusion Protection System (IPS) that can manage increasing traffic loads, higher network speeds, and strict Quality of Service (QoS) requirements. This new approach provides a strong foundation for next-generation network security technologies and products that address growing and unmet needs in the government and corporate sectors by delivering Optimal Network Security. Controlling access is an essential task for securing networks that are vital to private industry, government agencies, and the military. This access can be granted or denied based on the packet header or payload contents. For example, a simple network firewall enforces a security policy by inspecting and filtering the packet headers. As a complement to the firewall, an Intrusion Detection System (IDS) inspects the packet payload for known threat signatures; for example, virus or worm. Similar to a firewall policy, IDS policies consist of multiple rules that specify an action for matching packets. Each rule can specify different items, such as the signature contents and the signature location within the payload. When the firewall and IDS are merged into one device, the resulting system is referred to as an Intrusion Protection System (IPS), which provides both packet header and payload inspections. Having both types of inspections is very desirable and more manageable in a single device.

  5. High-Speed Scintillator for X-Ray Detection in Spheromak Plasma

    NASA Astrophysics Data System (ADS)

    Granstedt, E.; Bellan, P. M.

    2003-10-01

    A high-speed (10 ns) plastic (polyvinyltoluene) scintillator-photomultiplier assembly is being constructed for measuring x-ray emission produced in the Caltech spheromak formation experiment. X-ray emission has previously been observed in spheromak experiments [1] and has been attributed to runaway electrons. Since the Caltech spheromak formation experiment lasts for a short period of time (10-20 μs), a reset time on the order of 10 ns is necessary to identify and isolate individual photons in order to obtain adequate statistics. The scintillator has a thin aluminum filter to block incident light and a kapton vacuum window allowing detection of photons with energies above 10 keV. In order to compare the time-dependence of the scintillator signal to other plasma parameters and signals, the scintillator data is acquired by a set of eight 12-bit 100 Ms/s digitizers. An 8-way 50 Ohm power splitter in conjunction with staggered delay lines is used to enable 800 Ms/s sampling and so resolve the 2 ns rise-time scintillator signal. To avoid electromagnetic interference generated by the experiment, the device is housed in a highly shielded enclosure and is powered by an internal 12V rechargeable battery. [1] Chrien, R.F., Fernandez, J.C., Henins, I., Mayo, R.M., Wysocki, F.J. Nuclear Fusion. 31 (1991) 1390.

  6. High-speed two-dimensional bar-code detection system with time-sharing laser light emission method

    NASA Astrophysics Data System (ADS)

    Wakaumi, Hiroo; Nagasawa, Chikao

    2000-12-01

    A novel twodimensional bar-code detection system with time-sharing light emission laser diodes is proposed. A bias current allowing the laser diode to improve the light output rise time is optimized to slightly below the threshold of the diode, so that channel cross-talk among three-layer bar-code signals caused by the bias light can be kept small and a high-speed pulse modulation drive operation can be achieved. A prototype system for a three-layer bar code has achieved an effective scanning speed two and nine tenths times that of conventional scanners. It is estimated from the detection range that the number of time-sharing light emission laser diodes can be increased to at least four, when the current detection amplifier with a bandwidth of 6.4 MHz is used.

  7. EEG Single-Trial Detection of Gait Speed Changes during Treadmill Walk

    PubMed Central

    Lisi, Giuseppe; Morimoto, Jun

    2015-01-01

    In this study, we analyse the electroencephalography (EEG) signal associated with gait speed changes (i.e. acceleration or deceleration). For data acquisition, healthy subjects were asked to perform volitional speed changes between 0, 1, and 2 Km/h, during treadmill walk. Simultaneously, the treadmill controller modified the speed of the belt according to the subject’s linear speed. A classifier is trained to distinguish between the EEG signal associated with constant speed gait and with gait speed changes, respectively. Results indicate that the classification performance is fair to good for the majority of the subjects, with accuracies always above chance level, in both batch and pseudo-online approaches. Feature visualisation and equivalent dipole localisation suggest that the information used by the classifier is associated with increased activity in parietal areas, where mu and beta rhythms are suppressed during gait speed changes. Specifically, the parietal cortex may be involved in motor planning and visuomotor transformations throughout the online gait adaptation, which is in agreement with previous research. The findings of this study may help to shed light on the cortical involvement in human gait control, and represent a step towards a BMI for applications in post-stroke gait rehabilitation. PMID:25932947

  8. High-speed dual-wavelength demultiplexing and detection in a monolithic superlattice p-i-n waveguide detector array

    NASA Technical Reports Server (NTRS)

    Larsson, A.; Andrekson, P. A.; Andersson, P.; Eng, S. T.; Salzman, J.

    1986-01-01

    High-speed (1 Gbit/x) dual-wavelength demultiplexing and detection in a monolithic linear array of superlattice p-i-n photodetectors in a waveguide configuration is demonstrated. A crosstalk attenuation of 28 dB was achieved between two digital transmission channels with an interchannel wavelength spacing of 30 nm. The device performance is a result of an enhanced electroabsorption due to the quantum-confined Stark effect in the superlattice p-i-n diodes.

  9. A Vehicle Active Safety Model: Vehicle Speed Control Based on Driver Vigilance Detection Using Wearable EEG and Sparse Representation.

    PubMed

    Zhang, Zutao; Luo, Dianyuan; Rasim, Yagubov; Li, Yanjun; Meng, Guanjun; Xu, Jian; Wang, Chunbai

    2016-01-01

    In this paper, we present a vehicle active safety model for vehicle speed control based on driver vigilance detection using low-cost, comfortable, wearable electroencephalographic (EEG) sensors and sparse representation. The proposed system consists of three main steps, namely wireless wearable EEG collection, driver vigilance detection, and vehicle speed control strategy. First of all, a homemade low-cost comfortable wearable brain-computer interface (BCI) system with eight channels is designed for collecting the driver's EEG signal. Second, wavelet de-noising and down-sample algorithms are utilized to enhance the quality of EEG data, and Fast Fourier Transformation (FFT) is adopted to extract the EEG power spectrum density (PSD). In this step, sparse representation classification combined with k-singular value decomposition (KSVD) is firstly introduced in PSD to estimate the driver's vigilance level. Finally, a novel safety strategy of vehicle speed control, which controls the electronic throttle opening and automatic braking after driver fatigue detection using the above method, is presented to avoid serious collisions and traffic accidents. The simulation and practical testing results demonstrate the feasibility of the vehicle active safety model. PMID:26907278

  10. A Vehicle Active Safety Model: Vehicle Speed Control Based on Driver Vigilance Detection Using Wearable EEG and Sparse Representation

    PubMed Central

    Zhang, Zutao; Luo, Dianyuan; Rasim, Yagubov; Li, Yanjun; Meng, Guanjun; Xu, Jian; Wang, Chunbai

    2016-01-01

    In this paper, we present a vehicle active safety model for vehicle speed control based on driver vigilance detection using low-cost, comfortable, wearable electroencephalographic (EEG) sensors and sparse representation. The proposed system consists of three main steps, namely wireless wearable EEG collection, driver vigilance detection, and vehicle speed control strategy. First of all, a homemade low-cost comfortable wearable brain-computer interface (BCI) system with eight channels is designed for collecting the driver’s EEG signal. Second, wavelet de-noising and down-sample algorithms are utilized to enhance the quality of EEG data, and Fast Fourier Transformation (FFT) is adopted to extract the EEG power spectrum density (PSD). In this step, sparse representation classification combined with k-singular value decomposition (KSVD) is firstly introduced in PSD to estimate the driver’s vigilance level . Finally, a novel safety strategy of vehicle speed control, which controls the electronic throttle opening and automatic braking after driver fatigue detection using the above method, is presented to avoid serious collisions and traffic accidents. The simulation and practical testing results demonstrate the feasibility of the vehicle active safety model. PMID:26907278

  11. a New Method to Detect Regions Endangered by High Wind Speeds

    NASA Astrophysics Data System (ADS)

    Fischer, P.; Ehrensperger, S.; Krauß, T.

    2016-06-01

    In this study we evaluate whether the methodology of Boosted Regression Trees (BRT) suits for accurately predicting maximum wind speeds. As predictors a broad set of parameters derived from a Digital Elevation Model (DEM) acquired within the Shuttle Radar Topography Mission (SRTM) is used. The derived parameters describe the surface by means of quantities (e.g. slope, aspect) and quality (landform classification). Furthermore land cover data from the CORINE dataset is added. The response variable is maximum wind speed, measurements are provided by a network of weather stations. The area of interest is Switzerland, a country which suits perfectly for this study because of its highly dynamic orography and various landforms.

  12. Sliding mode observer based incipient sensor fault detection with application to high-speed railway traction device.

    PubMed

    Zhang, Kangkang; Jiang, Bin; Yan, Xing-Gang; Mao, Zehui

    2016-07-01

    This paper considers incipient sensor fault detection issue for a class of nonlinear systems with "observer unmatched" uncertainties. A particular fault detection sliding mode observer is designed for the augmented system formed by the original system and incipient sensor faults. The designed parameters are obtained using LMI and line filter techniques to guarantee that the generated residuals are robust to uncertainties and that sliding motion is not destroyed by faults. Then, three levels of novel adaptive thresholds are proposed based on the reduced order sliding mode dynamics, which effectively improve incipient sensor faults detectability. Case study of on the traction system in China Railway High-speed is presented to demonstrate the effectiveness of the proposed incipient senor faults detection schemes. PMID:27156675

  13. Tacholess Envelope Order Analysis and Its Application to Fault Detection of Rolling Element Bearings with Varying Speeds

    PubMed Central

    Zhao, Ming; Lin, Jing; Xu, Xiaoqiang; Lei, Yaguo

    2013-01-01

    Vibration analysis is an effective tool for the condition monitoring and fault diagnosis of rolling element bearings. Conventional diagnostic methods are based on the stationary assumption, thus they are not applicable to the diagnosis of bearings working under varying speed. This constraint limits the bearing diagnosis to the industrial application significantly. In order to extend the conventional diagnostic methods to speed variation cases, a tacholess envelope order analysis technique is proposed in this paper. In the proposed technique, a tacholess order tracking (TLOT) method is first introduced to extract the tachometer information from the vibration signal itself. On this basis, an envelope order spectrum (EOS) is utilized to recover the bearing characteristic frequencies in the order domain. By combining the advantages of TLOT and EOS, the proposed technique is capable of detecting bearing faults under varying speeds, even without the use of a tachometer. The effectiveness of the proposed method is demonstrated by both simulated signals and real vibration signals collected from locomotive roller bearings with faults on inner race, outer race and rollers, respectively. Analyzed results show that the proposed method could identify different bearing faults effectively and accurately under speed varying conditions. PMID:23959244

  14. Tacholess envelope order analysis and its application to fault detection of rolling element bearings with varying speeds.

    PubMed

    Zhao, Ming; Lin, Jing; Xu, Xiaoqiang; Lei, Yaguo

    2013-01-01

    Vibration analysis is an effective tool for the condition monitoring and fault diagnosis of rolling element bearings. Conventional diagnostic methods are based on the stationary assumption, thus they are not applicable to the diagnosis of bearings working under varying speed. This constraint limits the bearing diagnosis to the industrial application significantly. In order to extend the conventional diagnostic methods to speed variation cases, a tacholess envelope order analysis technique is proposed in this paper. In the proposed technique, a tacholess order tracking (TLOT) method is first introduced to extract the tachometer information from the vibration signal itself. On this basis, an envelope order spectrum (EOS) is utilized to recover the bearing characteristic frequencies in the order domain. By combining the advantages of TLOT and EOS, the proposed technique is capable of detecting bearing faults under varying speeds, even without the use of a tachometer. The effectiveness of the proposed method is demonstrated by both simulated signals and real vibration signals collected from locomotive roller bearings with faults on inner race, outer race and rollers, respectively. Analyzed results show that the proposed method could identify different bearing faults effectively and accurately under speed varying conditions. PMID:23959244

  15. Detecting interferences with iOS applications to measure speed of sound

    NASA Astrophysics Data System (ADS)

    Yavuz, Ahmet; Kağan Temiz, Burak

    2016-01-01

    Traditional experiments measuring the speed of sound consist of studying harmonics by changing the length of a glass tube closed at one end. In these experiments, the sound source and observer are outside of the tube. In this paper, we propose the modification of this old experiment by studying destructive interference in a pipe using a headset, iPhone and iPad. The iPhone is used as an emitter with signal generator application and the iPad is used as the receiver with a spectrogram application. Two experiments are carried out for measures: the emitter inside of the tube with the receiver outside, and vice versa. We conclude that it is even possible to adequately and easily measure the speed of sound using a cup or a can of coke with the method described in this paper.

  16. Integrated Seismic Survey for Detecting Landslide Effects on High Speed Rail Line at Istanbul-Turkey

    NASA Astrophysics Data System (ADS)

    Grit, Mert; Kanli, Ali Ismet

    2016-02-01

    In this study, Multichannel Analysis of Surface Waves Method (MASW), seismic refraction tomography and seismic reflection methods are used together at Silivri district in Istanbul - a district with a landslide problem because of the high speed rail line project crossing through the area. The landslide structure, border and depth of the slip plane are investigated and correlated within the local geology. According to the obtained 2D seismic sections, the landslide occurs through the East-West direction in the study area and the landslide slip plane with its border are clearly obtained under the subsurface. The results prove that the study area is suitable enough for the landslide development and this evolution also affects the high speed rail line project.

  17. Compound faults detection of rolling element bearing based on the generalized demodulation algorithm under time-varying rotational speed

    NASA Astrophysics Data System (ADS)

    Zhao, Dezun; Li, Jianyong; Cheng, Weidong; Wen, Weigang

    2016-09-01

    Multi-fault detection of the rolling element bearing under time-varying rotational speed presents a challenging issue due to its complexity, disproportion and interaction. Computed order analysis (COA) is one of the most effective approaches to remove the influences of speed fluctuation, and detect all the features of multi-fault. However, many interference components in the envelope order spectrum may lead to false diagnosis results, in addition, the deficiencies of computational accuracy and efficiency also cannot be neglected. To address these issues, a novel method for compound faults detection of rolling element bearing based on the generalized demodulation (GD) algorithm is proposed in this paper. The main idea of the proposed method is to exploit the unique property of the generalized demodulation algorithm in transforming an interested instantaneous frequency trajectory of compound faults bearing signal into a line paralleling to the time axis, and then the FFT algorithm can be directly applied to the transformed signal. This novel method does not need angular resampling algorithm which is the key step of the computed order analysis, and is hence free from the deficiencies of computational error and efficiency. On the other hand, it only acts on the instantaneous fault characteristic frequency trends in envelope signal of multi-fault bearing which include rich fault information, and is hence free from irrelevant items interferences. Both simulated and experimental faulty bearing signal analysis validate that the proposed method is effective and reliable on the compound faults detection of rolling element bearing under variable rotational speed conditions. The comprehensive comparison with the computed order analysis further shows that the proposed method produces higher accurate results in less computation time.

  18. High speed low power optical detection of sub-wavelength scatterer.

    PubMed

    Roy, S; Bouwens, Maryse; Wei, Lei; Pereira, S F; Urbach, H P; van der Walle, P

    2015-12-01

    Optical detection of scatterers on a flat substrate, generally done using dark field microscopy technique, is challenging since it requires high power illumination to obtain sufficient SNR (Signal to Noise Ratio) to be able to detect sub-wavelength particles. We developed a bright field technique, based on Fourier scatterometry, with special illumination and detection control to achieve this goal with a power level that can be sustained by most substrates including polymers. The performance of the system in a roll-to-roll line in production environment and strict throughput requirement is shown. PMID:26724010

  19. High speed low power optical detection of sub-wavelength scatterer

    NASA Astrophysics Data System (ADS)

    Roy, S.; Bouwens, Maryse; Wei, Lei; Pereira, S. F.; Urbach, H. P.; van der Walle, P.

    2015-12-01

    Optical detection of scatterers on a flat substrate, generally done using dark field microscopy technique, is challenging since it requires high power illumination to obtain sufficient SNR (Signal to Noise Ratio) to be able to detect sub-wavelength particles. We developed a bright field technique, based on Fourier scatterometry, with special illumination and detection control to achieve this goal with a power level that can be sustained by most substrates including polymers. The performance of the system in a roll-to-roll line in production environment and strict throughput requirement is shown.

  20. Estimating in-home walking speed distributions for unobtrusive detection of mild cognitive impairment in older adults.

    PubMed

    Akl, Ahmad; Mihailidis, Alex

    2015-01-01

    Timely recognition of cognitive impairment such as Alzheimer's disease is of great significance. Many smart systems, developed to continuously monitor older adults' health and cognition, use a number of predefined measures associated with the older adults' activity in their homes. However, this approach has been demonstrated to focus on idiosyncratic nuances of the individual subjects, and thus could potentially not perform as well when tested on new subjects. In this paper, we address this problem by building proper statistical models of older adults' in-home walking speed. Using the data pertaining to 15 older adults monitored for an average period of 3 years, we used linear regression with a Gaussian likelihood to model the subjects' in-home walking speed, and we used dynamic time warping to demonstrate significant difference between the walking speed distributions of the subjects when cognitively intact and when having mild cognitive impairment (MCI). Using a simple thresholding approach of the dynamic time warping costs, we were able to detect MCI in older adults with areas under the ROC curve and the precision-recall curve of 0.906 and 0.790, respectively, using a time frame of 12 weeks. PMID:26737457

  1. Estimating In-home Walking Speed Distributions for Unobtrusive Detection of Mild Cognitive Impairment in Older Adults*

    PubMed Central

    Akl, Ahmad; Mihailidis, Alex

    2016-01-01

    Timely recognition of cognitive impairment such as Alzheimer’s disease is of great significance. Many smart systems, developed to continuously monitor subjects’ health and cognition, use a number of predefined measures associated with the subjects’ activity in their homes. However, this approach has been demonstrated to focus on the idiosyncratic nuances of the individual subjects and thus could potentially not perform as well on new subjects. In this paper, we address this problem by building proper statistical models of the subjects’ in-home walking speed. Using the data pertaining to 15 older adults monitored for an average period of 3 years, we used linear regression with a Gaussian likelihood to model the in-home walking speed of the subjects, and we used dynamic time warping to demonstrate significant difference between the walking speed distributions of the subjects when cognitively intact and when suffering from MCI. Using a simple thresholding approach of the dynamic time warping costs, we were able to detect MCI in older adults with an area under the ROC curve and an area under the precision-recall curve of 0.906 and 0.790, respectively, using a time frame of 12 weeks. PMID:26737457

  2. Cognitive high speed defect detection and classification in MWIR images of laser welding

    NASA Astrophysics Data System (ADS)

    Lapido, Yago L.; Rodriguez-Araújo, Jorge; García-Díaz, Antón; Castro, Gemma; Vidal, Félix; Romero, Pablo; Vergara, Germán.

    2015-07-01

    We present a novel approach for real-time defect detection and classification in laser welding processes based on the use of uncooled PbSe image sensors working in the MWIR range. The spatial evolution of the melt pool was recorded and analyzed during several welding procedures. A machine learning approach was developed to classify welding defects. Principal components analysis (PCA) is used for dimensionality reduction of the melt pool data. This enhances classification results and enables on-line classification rates close to 1 kHz with non-optimized code prototyped in Python. These results point to the feasibility of real-time defect detection.

  3. Handheld photoacoustic probe to detect both melanoma depth and volume at high speed in vivo

    PubMed Central

    Zhu, Liren; Li, Chiye; Cornelius, Lynn A.; Wang, Lihong V.

    2015-01-01

    We applied a linear-array-based photoacoustic probe to detect melanin-containing melanoma tumor depth and volume in nude mice in vivo. This system can image melanomas at five frames per second (fps), which is much faster than our previous handheld single transducer system (0.1 fps). We first theoretically show that, in addition to the higher frame rate, almost the entire boundary of the melanoma can be detected by the linear-array-based probe, while only the horizontal boundary could be detected by the previous system. Then we demonstrate the ability of this linear-array-based system in measuring both the depth and volume of melanoma through phantom, ex vivo, and in vivo experiments. The volume detection ability also enables us to accurately calculate the rate of growth of the tumor, which is an important parameter in quantifying the tumor activity. Our results show that this system can be used for clinical melanoma diagnosis and treatment in humans at the bedside. PMID:25676898

  4. A robust hypothesis test for the sensitive detection of constant speed radiation moving sources

    NASA Astrophysics Data System (ADS)

    Dumazert, Jonathan; Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Moline, Yoann; Sannié, Guillaume; Gameiro, Jordan; Normand, Stéphane; Méchin, Laurence

    2015-09-01

    Radiation Portal Monitors are deployed in linear networks to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal-to-noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive backgrounds, and a vehicle source carrier under the same respectively high and low count rate radioactive backgrounds, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm. It also guarantees that the optimal coverage factor for this compromise remains stable regardless of signal-to-noise ratio variations between 2 and 0.8, therefore allowing the final user to parametrize the test with the sole prior knowledge of background amplitude.

  5. Attentional Mechanisms in Simple Visual Detection: A Speed-Accuracy Trade-Off Analysis

    ERIC Educational Resources Information Center

    Liu, Charles C.; Wolfgang, Bradley J.; Smith, Philip L.

    2009-01-01

    Recent spatial cuing studies have shown that detection sensitivity can be increased by the allocation of attention. This increase has been attributed to one of two mechanisms: signal enhancement or uncertainty reduction. Signal enhancement is an increase in the signal-to-noise ratio at the cued location; uncertainty reduction is a reduction in the…

  6. Dynamic faces speed up the onset of auditory cortical spiking responses during vocal detection

    PubMed Central

    Chandrasekaran, Chandramouli; Lemus, Luis; Ghazanfar, Asif A.

    2013-01-01

    How low-level sensory areas help mediate the detection and discrimination advantages of integrating faces and voices is the subject of intense debate. To gain insights, we investigated the role of the auditory cortex in face/voice integration in macaque monkeys performing a vocal-detection task. Behaviorally, subjects were slower to detect vocalizations as the signal-to-noise ratio decreased, but seeing mouth movements associated with vocalizations sped up detection. Paralleling this behavioral relationship, as the signal to noise ratio decreased, the onset of spiking responses were delayed and magnitudes were decreased. However, when mouth motion accompanied the vocalization, these responses were uniformly faster. Conversely, and at odds with previous assumptions regarding the neural basis of face/voice integration, changes in the magnitude of neural responses were not related consistently to audiovisual behavior. Taken together, our data reveal that facilitation of spike latency is a means by which the auditory cortex partially mediates the reaction time benefits of combining faces and voices. PMID:24218574

  7. Aerodynamic distortion propagation calculation in application of high-speed target detection by laser

    NASA Astrophysics Data System (ADS)

    Zheng, Yonghui; Sun, Huayan; Zhao, Yanzhong; Chen, Jianbiao

    2015-10-01

    Active laser detection technique has a broad application prospect in antimissile and air defense, however the aerodynamic flow field around the planes and missiles cause serious distortion effect on the detecting laser beams. There are many computational fluid dynamics(CFD) codes that can predict the air density distribution and also the density fluctuations of the flow field, it's necessary for physical optics to be used to predict the distortion properties after propagation through the complex process. Aiming at the physical process of laser propagation in "Cat-eye" lenses and aerodynamic flow field for twice, distortion propagation calculation method is researched in this paper. In the minds of dividing the whole process into two parts, and tread the aero-optical optical path difference as a phase distortion, the incidence and reflection process are calculated using Collins formula and angular spectrum diffraction theory respectively. In addition, turbulent performance of the aerodynamic flow field is estimated according to the electromagnetic propagation theory through a random medium, the rms optical path difference and Strehl ratio of the turbulent optical distortion are obtained. Finally, Computational fluid mechanics and aero-optical distortion properties of the detecting laser beams are calculated with the hemisphere-on-cylinder turret as an example, calculation results are showed and analysed.

  8. ''High-Speed, Photon-Counting Camera for the Detection of Extrasolar Planets''

    SciTech Connect

    Ullom, J; Cunningham, M; Macintosh, B; Miyazaki, T; Labov, S

    2003-02-07

    The search for extrasolar planets--planets orbiting stars outside out solar system-- is motivated by the desire to discover small planets similar to Earth. Since small planets are difficult to detect, the first step is finding giant planets with large orbits, like Jupiter. Solar systems containing these planets may have smaller, Earth-like planets travelling closer to the parent star. However, current methods detect extrasolar planets indirectly by observing a planet's gravitational influence on its parent star. These methods are primarily sensitive to giant planets with small orbits. A new method is needed to directly observe planets with large orbits. Direct observation can also provide additional information about a planet's composition and/or orbit. Directly observing an extrasolar planet from Earth is challenging because of the relative proximity of the planet to its parent star. Although a large, terrestrial telescope can provide the angular resolution necessary to visually separate the planet from the star, atmospheric turbulence limits the telescope's performance. In addition, the parent star appears much brighter than the planet. Adaptive optics (AO) can increase a planet's brightness, but they have little effect on residual star glare.

  9. Simultaneous high-speed 3D flame front detection and tomographic PIV

    NASA Astrophysics Data System (ADS)

    Ebi, Dominik; Clemens, Noel T.

    2016-03-01

    A technique capable of detecting the instantaneous, time-resolved, 3D flame topography is successfully demonstrated in a lean-premixed swirl flame undergoing flashback. A simultaneous measurement of the volumetric velocity field is possible without the need for additional hardware. Droplets which vaporize in the preheat zone of the flame serve as the marker for the flame front. The droplets are illuminated with a laser and imaged from four different views followed by a tomographic reconstruction to obtain the volumetric particle field. Void regions in the reconstructed particle field, which correspond to regions of burnt gas, are detected with a series of image processing steps. The interface separating the void region from regions filled with particles is defined as the flame surface. The velocity field in the unburnt gas is measured using tomographic PIV. The resulting data include the simultaneous 3D flame front and 3D volumetric velocity field at 5 kHz. The technique is applied to a lean-premixed (ϕ  =  0.8), swirling methane-air flame and validated against simultaneously acquired planar measurements. The mean error associated with the reconstructed 3D flame topography is about 0.4 mm, which is smaller than the flame thickness under the studied conditions. The mean error associated with the volumetric velocity field is about 0.2 m s-1.

  10. Influence of confocal scanning laser microscopy specific acquisition parameters on the detection and matching of speeded-up robust features.

    PubMed

    Stanciu, Stefan G; Hristu, Radu; Stanciu, George A

    2011-04-01

    The robustness and distinctiveness of local features to various object or scene deformations and to modifications of the acquisition parameters play key roles in the design of many computer vision applications. In this paper we present the results of our experiments on the behavior of a recently developed technique for local feature detection and description, Speeded-Up Robust Features (SURF), regarding image modifications specific to Confocal Scanning Laser Microscopy (CSLM). We analyze the repeatability of detected SURF keypoints and the precision-recall of their matching under modifications of three important CSLM parameters: pinhole aperture, photomultiplier (PMT) gain and laser beam power. During any investigation by CSLM these three parameters have to be modified, individually or together, in order to optimize the contrast and the Signal Noise Ratio (SNR), being also inherently modified when changing the microscope objective. Our experiments show that an important amount of SURF features can be detected at the same physical locations in images collected at different values of the pinhole aperture, PMT gain and laser beam power, and further on can be successfully matched based on their descriptors. In the final part, we exemplify the potential of SURF in CSLM imaging by presenting a SURF-based computer vision application that deals with the mosaicing of images collected by this technique. PMID:21349249

  11. High-speed asynchronous optical sampling for high-sensitivity detection of coherent phonons

    NASA Astrophysics Data System (ADS)

    Dekorsy, T.; Taubert, R.; Hudert, F.; Schrenk, G.; Bartels, A.; Cerna, R.; Kotaidis, V.; Plech, A.; Köhler, K.; Schmitz, J.; Wagner, J.

    2007-12-01

    A new optical pump-probe technique is implemented for the investigation of coherent acoustic phonon dynamics in the GHz to THz frequency range which is based on two asynchronously linked femtosecond lasers. Asynchronous optical sampling (ASOPS) provides the performance of on all-optical oscilloscope and allows us to record optically induced lattice dynamics over nanosecond times with femtosecond resolution at scan rates of 10 kHz without any moving part in the set-up. Within 1 minute of data acquisition time signal-to-noise ratios better than 107 are achieved. We present examples of the high-sensitivity detection of coherent phonons in superlattices and of the coherent acoustic vibration of metallic nanoparticles.

  12. A microfabricated optofluidic ring resonator for sensitive, high-speed detection of volatile organic compounds.

    PubMed

    Scholten, Kee; Fan, Xudong; Zellers, Edward T

    2014-10-01

    Advances in microanalytical systems for multi-vapor determinations to date have been impeded by limitations associated with the microsensor technologies employed. Here we introduce a microfabricated optofluidic ring resonator (μOFRR) sensor that addresses many of these limitations. The μOFRR combines vapor sensing and fluidic transport functions in a monolithic microstructure comprising a hollow, vertical SiOx cylinder (250 μm i.d., 1.2 μm wall thickness; 85 μm height) with a central quasi-toroidal mode-confinement section, grown and partially released from a Si substrate. The device also integrates on-chip fluidic-interconnection and fiber-optic probe alignment features. High-Q whispering gallery modes generated with a tunable 1550 nm laser exhibit rapid, reversible shifts in resonant wavelength arising from polymer swelling and refractive index changes as vapors partition into the ~300 nm PDMS film lining the cylinder. Steady-state sensor responses varied in proportion to concentration over a 50-fold range for the five organic vapors tested, providing calculated detection limits as low as 0.5 ppm (v/v) (for m-xylene and ethylbenzene). In dynamic exposure tests, responses to 5 μL injected m-xylene vapor pulses were 710 ms wide and were only 18% broader than those from a reference flame-ionization detector and also varied linearly with injected mass; 180 pg was measured and the calculated detection limit was 49 pg without use of preconcentration or split injection, at a flow rate compatible with efficient chromatographic separations. Coupling of this μOFRR with a micromachined gas chromatographic separation column is demonstrated. PMID:25131718

  13. Quantitative sensory and motor measures detect change over time and correlate with walking speed in individuals with multiple sclerosis

    PubMed Central

    Zackowski, Kathy M.; Wang, Joseph I.; McGready, John; Calabresi, Peter A.; Newsome, Scott D.

    2014-01-01

    Background Impairments of sensation, strength, and walking are common in multiple sclerosis(MS). The relationship among these abnormalities and how they change over time remains unclear. Objective To determine the extent that quantitative lower extremity sensory and motor measures detect abnormalities over time, relate to global disability, and to walking speed in individuals with MS. Methods This prospective, longitudinal analysis evaluated 136 MS subjects. Measures included measures of leg strength, sensation, the Expanded Disability Status Scale(EDSS) and timed 25-foot walk test(T25FW). Mixed effects regression models were used. Results Our cohort’s mean age is 44.3±10.8 years (mean±SD), EDSS score range 0–7.5, 66% were females, and follow-up time was 2.1±1.2 years. Strength significantly changed over time; the RRMS group demonstrated the greatest changes in ADF (3.3 lbs/yr) while the PPMS group showed significant HF changes (−2.1 lbs/yr). Walking speed was affected most by HF, especially in the weakest individuals (HF<20lbs); T25FW increased by 0.20 seconds(s) for each 1lb loss (p=0.001). Likewise T25FW changed by 0.19s for each 1lb change in ADF (p<0.01). Conclusion Quantitative measures detected changes in sensation and strength over time, despite a stable respective functional systems scores of the EDSS. Quantitative measurement tools may improve the sensitivity of disability measures in MS and further investigation of these tools as outcomes in future clinical trials of rehabilitative and neuroreparative interventions is warranted. PMID:25692092

  14. Effects of leading-edge tubercles on wing flutter speeds.

    PubMed

    Ng, B F; New, T H; Palacios, R

    2016-06-01

    The dynamic aeroelastic effects on wings modified with bio-inspired leading-edge (LE) tubercles are examined in this study. We adopt a state-space aeroelastic model via the coupling of unsteady vortex-lattice method and a composite beam to evaluate stability margins as a result of LE tubercles on a generic wing. The unsteady aerodynamics and spanwise mass variations due to LE tubercles have counteracting effects on stability margins with the former having dominant influence. When coupled, flutter speed is observed to be 5% higher, and this is accompanied by close to 6% decrease in reduced frequencies as an indication of lower structural stiffness requirements for wings with LE tubercles. Both tubercle amplitude and wavelength have similar influences over the change in flutter speeds, and such modifications to the LE would have minimal effect on stability margins when concentrated inboard of the wing. Lastly, when used in sweptback wings, LE tubercles are observed to have smaller impacts on stability margins as the sweep angle is increased. PMID:27070824

  15. A laser-optical sensor system for blade vibration detection of high-speed compressors

    NASA Astrophysics Data System (ADS)

    Neumann, Mathias; Dreier, Florian; Günther, Philipp; Wilke, Ulrich; Fischer, Andreas; Büttner, Lars; Holzinger, Felix; Schiffer, Heinz-Peter; Czarske, Jürgen

    2015-12-01

    Improved efficiency as well as increased lifetime of turbines and compressors are important goals in turbomachinery development. A significant enhancement to accomplish these aims can be seen in online monitoring of the operating parameters of the machines. During the operation of compressors it is of high interest to predict critical events like flutter or stall which can be achieved by observing blade deformations and vibrations. We have developed a laser Doppler distance sensor (LDDS), which is capable of simultaneously measuring the radial blade expansions, the circumferential blade deflections as well as the circumferential velocities of the rotor blade tips. As a result, an increase of blade vibrations is measured before stall at characteristic frequencies. While the detected vibration frequencies and the vibration increase are in agreement with the measurement results of a commercial capacitive blade tip timing system, the measured values of the vibration amplitudes differ by a factor of three. This difference can be mainly attributed to the different measurement locations and to the different measurement approaches. Since the LDDS is applicable to metal as well as ceramic, carbon-fiber and glass-fiber reinforced composite blades, a universally applicable sensor system for stall prediction and status monitoring is presented.

  16. LuAlO3: A high density, high speed scintillator for gamma detection

    NASA Astrophysics Data System (ADS)

    Moses, W. W.; Derenzo, S. E.; Fyodorov, A.; Korzhik, M.; Gektin, A.; Minkov, B.; Aslanov, V.

    1994-11-01

    We present measurements of the scintillation properties cerium doped lutetium aluminum perovskite, LuAlO3:Ce, new dense ((rho)=8.34 g/cm(sup 3)) inorganic scintillator. This material has a 511 keV interaction length and photoelectric fraction 1.1 cm and 32% respectively, which are well suited to gamma ray detection. In powdered form with 0.5% cerium concentration, the scintillation light output is estimated to be 9,600 photons/MeV of deposited energy, the emission spectrum is a single peak centered at 390 nm, and the fluorescence lifetime is described by the sum of 3 exponential terms, with 60% of the light being emitted with a 11 ns decay time, 26% with a 28 ns decay time, and 13% with a 835 ns decay time. Single crystals contaminated with =10% lutetium aluminum garnet (Lu3Al5Ol2) have significantly altered scintillation properties. The light output is 26,000 photons/MeV (3.2 times that of BGO), but the decay time increases significantly (1% of the light is emitted with a 10 ns decay time, 15% with a 245 ns decay time, and 85% with a 2010 ns decay time) and the emission spectrum is dominated by a peak centered at 315 nm with a secondary peak centered at 500 rum. The short decay lifetime, high density, and reasonable light output of LuAlO3:Ce (the perovskite phase) suggest that it is useful for applications where high counting rates, good stopping power, good energy resolution, and fast timing are important. However, it is necessary to grow single crystals that are uncontaminated by the garnet phase to realize these properties.

  17. LuAlO{sub 3}: A high density, high speed scintillator for gamma detection

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.; Fyodorov, A.; Korzhik, M.; Gektin, A.; Minkov, B.; Aslanov, V.

    1994-11-01

    We present measurements of the scintillation properties cerium doped lutetium aluminum perovskite, LuAlO{sub 3}:C, new dense ({rho}=8.34 g/cm{sup 3}) inorganic scintillator. This material has a 511 keV interaction length and photoelectric fraction 1.1 cm and 32% respectively, which are well suited to gamma ray detection. In powdered form with 0.5% cerium concentration, the scintillation light output is estimated to be 9,600 photons/MeV of deposited energy, the emission spectrum is a single peak centered at 390 nm, and the fluorescence lifetime is described by the sum of 3 exponential terms, with 60% of the light being emitted with a 11 ns decay time, 26% with a 28 ns decay time, and 13% with a 835 ns decay time. Single crystals contaminated with =10% lutetium aluminum garnet (Lu{sub 3}Al{sub 5}O{sub l2}) have significantly altered scintillation properties. The light output is 26,000 photons/MeV (3.2 times that of BGO), but the decay time increases significantly (1% of the light is emitted with a 10 ns decay time, 15% with a 245 ns decay time, and 85% with a 2010 ns decay time) and the emission spectrum is dominated by a peak centered at 315 nm with a secondary peak centered at 500 rum. The short decay lifetime, high density, and reasonable light output of LuAlO{sub 3}:C (the perovskite phase) suggest that it is useful for applications where high counting rates, good stopping power, good energy resolution, and fast timing are important. However, it is necessary to grow single crystals that are uncontaminated by the garnet phase to realize these properties.

  18. A high-speed 12-layer two-dimensional bar code detection system with wideband photodetection amplifier and balanced raster scanner

    NASA Astrophysics Data System (ADS)

    Wakaumi, Hiroo; Ajiki, Hiroshi

    1998-12-01

    A high-speed 12-layer 2D bar-code detection system (BCDS) consisting of a photodetection amplifier with an amplification-type current-voltage converter and a balanced raster scanner combined with the complementary light emission drive method for laser diodes, has been developed in order to provide both a high effective scanning speed and multi-layer bar-code detection. This BCDS performs 1,250 scan/s, which is two and a half times the scanning speed of a conventional bar-code detection system. A new theoretical modulation model that gives an accurate model for laser scanning beam traces obtained by the balanced raster scanner is proposed. This model allows an optimum BCDS to be designed easily.

  19. Novel MDM-PON scheme utilizing self-homodyne detection for high-speed/capacity access networks.

    PubMed

    Chen, Yuanxiang; Li, Juhao; Zhu, Paikun; Wu, Zhongying; Zhou, Peng; Tian, Yu; Ren, Fang; Yu, Jinyi; Ge, Dawei; Chen, Jingbiao; He, Yongqi; Chen, Zhangyuan

    2015-12-14

    In this paper, we propose a cost-effective, energy-saving mode-division-multiplexing passive optical network (MDM-PON) scheme utilizing self-homodyne detection for high-speed/capacity access network based on low modal-crosstalk few-mode fiber (FMF) and all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). In the proposed scheme, one of the spatial modes is used to transmit a portion of signal carrier (namely pilot-tone) as the local oscillator (LO), while the others are used for signal-bearing channels. At the receiver, the pilot-tone and the signal can be separated without strong crosstalk and sent to the receiver for coherent detection. The spectral efficiency (SE) is significantly enhanced when multiple spatial channels are used. Meanwhile, the self-homodyne detection scheme can effectively suppress laser phase noise, which relaxes the requirement for the lasers line-width at the optical line terminal or optical network units (OLT/ONUs). The digital signal processing (DSP) at the receiver is also simplified since it removes the need for frequency offset compensation and complex phase correction, which reduces the computational complexity and energy consumption. Polarization division multiplexing (PDM) that offers doubled SE is also supported by the scheme. The proposed scheme is scalable to multi-wavelength application when wavelength MUX/DEMUX is utilized. Utilizing the proposed scheme, we demonstrate a proof of concept 4 × 40-Gb/s orthogonal frequency division multiplexing (OFDM) transmission over 55-km FMF using low modal-crosstalk two-mode FMF and MUX/DEMUX with error free operation. Compared with back to back case, less than 1-dB Q-factor penalty is observed after 55-km FMF of the four channels. Signal power and pilot-tone power are also optimized to achieve the optimal transmission performance. PMID:26698996

  20. Evaluation of the Speed-oligo Direct Mycobacterium tuberculosis Assay for Molecular Detection of Mycobacteria in Clinical Respiratory Specimens

    PubMed Central

    Lara-Oya, Ana; Mendoza-Lopez, Pablo; Rodriguez-Granger, Javier; Fernández-Sánchez, Ana María; Bermúdez-Ruiz, María Pilar; Toro-Peinado, Inmaculada; Palop-Borrás, Begoña; Navarro-Marí, Jose María

    2013-01-01

    We present the first evaluation of a novel molecular assay, the Speed-oligo Direct Mycobacterium tuberculosis (SO-DMT) assay, which is based on PCR combined with a dipstick for the detection of mycobacteria and the specific identification of M. tuberculosis complex (MTC) in respiratory specimens. A blind evaluation was carried out in two stages: first, under experimental conditions on convenience samples comprising 20 negative specimens, 44 smear- and culture-positive respiratory specimens, and 11 sputa inoculated with various mycobacterium-related organisms; and second, in the routine workflow of 566 fresh respiratory specimens (4.9% acid-fast bacillus [AFB] smear positives, 7.6% MTC positives, and 1.8% nontuberculous mycobacteria [NTM] culture positives) from two Mycobacterium laboratories. SO-DMT assay showed no reactivity in any of the mycobacterium-free specimens or in those with mycobacterium-related organisms. Compared to culture, the sensitivity in the selected smear-positive specimens was 0.91 (0.92 for MTC and 0.90 for NTM), and there was no molecular detection of NTM in a tuberculosis case or vice versa. With respect to culture and clinical data, the sensitivity, specificity, and positive and negative predictive values for the SO-DMT system in routine specimens were 0.76 (0.93 in smear positives [1.0 for MTC and 0.5 for NTM] and 0.56 in smear negatives [0.68 for MTC and 0.16 for NTM]), 0.99, 0.85 (1.00 in smear positives and 0.68 in smear negatives), and 0.97, respectively. Molecular misidentification of NTM cases occurred when testing 2 gastric aspirates from two children with clinically but not microbiologically confirmed lung tuberculosis. The SO-DMT assay appears to be a fast and easy alternative for detecting mycobacteria and differentiating MTC from NTM in smear-positive respiratory specimens. PMID:23100355

  1. Noise source detection and measurement in a supersonic air jet using Ultra-high Speed Rainbow Schlieren Deflectometry

    NASA Astrophysics Data System (ADS)

    Rajora, Manik; Agrawal, Ajay; Mitchell, William; Kolhe, Pankaj

    2012-11-01

    Supersonic jets emit noise from various regions including the shear layer containing vortical structures, various shock cell structures in the near field and the downstream jet core breakdown region. Sound waves emitted from these various regions interact with each other and produce distinct noise spectra away from the jet, which depends upon the measurement location. Typically sound is detected by intrusive probes that provide measurements at a specific location, which makes it difficult to identify the origination point of such noise in a supersonic jet. In this study, an ultra-high speed Rainbow Schlieren Deflectometry (RSD) technique has been developed to optically visualize not only the supersonic jet flow but also the sound waves emanating from it in real time. Color schlieren images are acquired at up to 250,000 frames per second to capture the sound wave propagation with adequate spatial resolution. Optical components of the system were optimized to improve the spatial and temporal resolutions and hence, the schlieren video quality. To the best of our knowledge, this is the first time sound wave propagation from supersonic jets has been recorded in real time on a schlieren video. Acquired color schlieren images are amenable to quantitative analysis, and can provide data on sound power and sound wave frequency across the whole field. This project was funded by NSF REU 1062611 and Department of Energy for Institue for Sustainable Energy EE003134.

  2. Step-Detection and Adaptive Step-Length Estimation for Pedestrian Dead-Reckoning at Various Walking Speeds Using a Smartphone.

    PubMed

    Ho, Ngoc-Huynh; Truong, Phuc Huu; Jeong, Gu-Min

    2016-01-01

    We propose a walking distance estimation method based on an adaptive step-length estimator at various walking speeds using a smartphone. First, we apply a fast Fourier transform (FFT)-based smoother on the acceleration data collected by the smartphone to remove the interference signals. Then, we analyze these data using a set of step-detection rules in order to detect walking steps. Using an adaptive estimator, which is based on a model of average step speed, we accurately obtain the walking step length. To evaluate the accuracy of the proposed method, we examine the distance estimation for four different distances and three speed levels. The experimental results show that the proposed method significantly outperforms conventional estimation methods in terms of accuracy. PMID:27598171

  3. Bio-inspired heterogeneous composites for broadband vibration mitigation

    NASA Astrophysics Data System (ADS)

    Chen, Yanyu; Wang, Lifeng

    2015-12-01

    Structural biological materials have developed heterogeneous and hierarchical architectures that are responsible for the outstanding performance to provide protection against environmental threats including static and dynamic loading. Inspired by this observation, this research aims to develop new material and structural concepts for broadband vibration mitigation. The proposed composite materials possess a two-layered heterogeneous architecture where both layers consist of high-volume platelet-shape reinforcements and low-volume matrix, similar to the well-known “brick and mortar” microstructure of biological composites. Using finite element method, we numerically demonstrated that broadband wave attenuation zones can be achieved by tailoring the geometric features of the heterogeneous architecture. We reveal that the resulting broadband attenuation zones are gained by directly superimposing the attenuation zones in each constituent layer. This mechanism is further confirmed by the investigation into the phonon dispersion relation of each layer. Importantly, the broadband wave attenuation capability will be maintained when the mineral platelet orientation is locally manipulated, yet a contrast between the mineral platelet concentrations of the two constituent layers is essential. The findings of this work will provide new opportunities to design heterogeneous composites for broadband vibration mitigation and impact resistance under mechanically challenging environmental conditions.

  4. Bio-inspired heterogeneous composites for broadband vibration mitigation

    PubMed Central

    Chen, Yanyu; Wang, Lifeng

    2015-01-01

    Structural biological materials have developed heterogeneous and hierarchical architectures that are responsible for the outstanding performance to provide protection against environmental threats including static and dynamic loading. Inspired by this observation, this research aims to develop new material and structural concepts for broadband vibration mitigation. The proposed composite materials possess a two-layered heterogeneous architecture where both layers consist of high-volume platelet-shape reinforcements and low-volume matrix, similar to the well-known “brick and mortar” microstructure of biological composites. Using finite element method, we numerically demonstrated that broadband wave attenuation zones can be achieved by tailoring the geometric features of the heterogeneous architecture. We reveal that the resulting broadband attenuation zones are gained by directly superimposing the attenuation zones in each constituent layer. This mechanism is further confirmed by the investigation into the phonon dispersion relation of each layer. Importantly, the broadband wave attenuation capability will be maintained when the mineral platelet orientation is locally manipulated, yet a contrast between the mineral platelet concentrations of the two constituent layers is essential. The findings of this work will provide new opportunities to design heterogeneous composites for broadband vibration mitigation and impact resistance under mechanically challenging environmental conditions. PMID:26642932

  5. Designing prosthetic knee joints with bio-inspired bearing surfaces.

    PubMed

    Qiu, Mingfeng; Chyr, Anthony; Sanders, Anthony P; Raeymaekers, Bart

    2014-09-01

    It has long been known that articular cartilage exhibits a surface microtexture with shallow indentations. By contrast, prosthetic joints consist of ultra-smooth bearing surfaces, the longevity of which does not reach that of natural cartilage. We show that adding a microtexture to the smooth femoral component of a prosthetic knee joint reduces friction by increasing the lubricant film thickness between the bearing surfaces of the knee. We have implemented an elastohydrodynamic lubrication model to optimize the geometry of the microtexture, while taking into account the deformation of the polyethylene tibial insert. We have manufactured several microtexture designs on a surrogate femoral component, and experimentally demonstrate that the microtexture reduces friction between the surrogate femoral component and tibial insert. PMID:25049441

  6. Hollow carbon spheres in microwaves: Bio inspired absorbing coating

    NASA Astrophysics Data System (ADS)

    Bychanok, D.; Li, S.; Sanchez-Sanchez, A.; Gorokhov, G.; Kuzhir, P.; Ogrin, F. Y.; Pasc, A.; Ballweg, T.; Mandel, K.; Szczurek, A.; Fierro, V.; Celzard, A.

    2016-01-01

    The electromagnetic response of a heterostructure based on a monolayer of hollow glassy carbon spheres packed in 2D was experimentally surveyed with respect to its response to microwaves, namely, the Ka-band (26-37 GHz) frequency range. Such an ordered monolayer of spheres mimics the well-known "moth-eye"-like coating structures, which are widely used for designing anti-reflective surfaces, and was modelled with the long-wave approximation. Based on the experimental and modelling results, we demonstrate that carbon hollow spheres may be used for building an extremely lightweight, almost perfectly absorbing, coating for Ka-band applications.

  7. Protein multiple sequence alignment by hybrid bio-inspired algorithms.

    PubMed

    Cutello, Vincenzo; Nicosia, Giuseppe; Pavone, Mario; Prizzi, Igor

    2011-03-01

    This article presents an immune inspired algorithm to tackle the Multiple Sequence Alignment (MSA) problem. MSA is one of the most important tasks in biological sequence analysis. Although this paper focuses on protein alignments, most of the discussion and methodology may also be applied to DNA alignments. The problem of finding the multiple alignment was investigated in the study by Bonizzoni and Vedova and Wang and Jiang, and proved to be a NP-hard (non-deterministic polynomial-time hard) problem. The presented algorithm, called Immunological Multiple Sequence Alignment Algorithm (IMSA), incorporates two new strategies to create the initial population and specific ad hoc mutation operators. It is based on the 'weighted sum of pairs' as objective function, to evaluate a given candidate alignment. IMSA was tested using both classical benchmarks of BAliBASE (versions 1.0, 2.0 and 3.0), and experimental results indicate that it is comparable with state-of-the-art multiple alignment algorithms, in terms of quality of alignments, weighted Sums-of-Pairs (SP) and Column Score (CS) values. The main novelty of IMSA is its ability to generate more than a single suboptimal alignment, for every MSA instance; this behaviour is due to the stochastic nature of the algorithm and of the populations evolved during the convergence process. This feature will help the decision maker to assess and select a biologically relevant multiple sequence alignment. Finally, the designed algorithm can be used as a local search procedure to properly explore promising alignments of the search space. PMID:21071394

  8. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  9. A tale of three bio-inspired computational approaches

    NASA Astrophysics Data System (ADS)

    Schaffer, J. David

    2014-05-01

    I will provide a high level walk-through for three computational approaches derived from Nature. First, evolutionary computation implements what we may call the "mother of all adaptive processes." Some variants on the basic algorithms will be sketched and some lessons I have gleaned from three decades of working with EC will be covered. Then neural networks, computational approaches that have long been studied as possible ways to make "thinking machines", an old dream of man's, and based upon the only known existing example of intelligence. Then, a little overview of attempts to combine these two approaches that some hope will allow us to evolve machines we could never hand-craft. Finally, I will touch on artificial immune systems, Nature's highly sophisticated defense mechanism, that has emerged in two major stages, the innate and the adaptive immune systems. This technology is finding applications in the cyber security world.

  10. Bio-inspired Aloe vera sponges for biomedical applications.

    PubMed

    Silva, S S; Oliveira, M B; Mano, J F; Reis, R L

    2014-11-01

    Chemical composition and biological properties of Aloe vera (AV), a tropical plant, explain its potential use for cosmetic, nutritional and biomedical applications. AV gel present in AV leaves is rich in several compounds, nutrients and polysaccharides. This work proposes using AV gel complex structure and chemical composition, associated with freeze-drying, to produce sponges. To increase the structures stability in aqueous media, a thin coating of gellan gum (GG), was applied onto AV gel. AV-based sponges showed a heterogeneous porous formation, interconnected pores and good porosity (72-77%). The coating with a GG layer onto AV influenced the stability, swelling behavior and mechanical properties of the resulting sponges. Moreover, sponges provided the sustained release of BSA-FTIC, used as a model protein, over 3 weeks. Also, in vitro cell culture studies evidenced that sponges are not cytotoxic for a mouse fibroblast-like cell line. Therefore, developed AV-based sponges have potential use in biomedical applications. PMID:25129743

  11. Bio-inspired strategies for designing antifouling biomaterials.

    PubMed

    Damodaran, Vinod B; Murthy, N Sanjeeva

    2016-01-01

    Contamination of biomedical devices in a biological medium, biofouling, is a major cause of infection and is entirely avoidable. This mini-review will coherently present the broad range of antifouling strategies, germicidal, preventive and cleaning using one or more of biological, chemical and physical techniques. These techniques will be discussed from the point of view of their ability to inhibit protein adsorption, usually the first step that eventually leads to fouling. Many of these approaches draw their inspiration from nature, such as emulating the nitric oxide production in endothelium, use of peptoids that mimic protein repellant peptides, zwitterionic functionalities found in membrane structures, and catechol functionalities used by mussel to immobilize poly(ethylene glycol) (PEG). More intriguing are the physical modifications, creation of micropatterns on the surface to control the hydration layer, making them either superhydrophobic or superhydrophilic. This has led to technologies that emulate the texture of shark skin, and the superhyprophobicity of self-cleaning textures found in lotus leaves. The mechanism of antifouling in each of these methods is described, and implementation of these ideas is illustrated with examples in a way that could be adapted to prevent infection in medical devices. PMID:27326371

  12. Tribology of bio-inspired nanowrinkled films on ultrasoft substrates

    PubMed Central

    Lackner, Juergen M.; Waldhauser, Wolfgang; Major, Lukasz; Teichert, Christian; Hartmann, Paul

    2013-01-01

    Biomimetic design of new materials uses nature as antetype, learning from billions of years of evolution. This work emphasizes the mechanical and tribological properties of skin, combining both hardness and wear resistance of its surface (the stratum corneum) with high elasticity of the bulk (epidermis, dermis, hypodermis). The key for combination of such opposite properties is wrinkling, being consequence of intrinsic stresses in the bulk (soft tissue): Tribological contact to counterparts below the stress threshold for tissue trauma occurs on the thick hard stratum corneum layer pads, while tensile loads smooth out wrinkles in between these pads. Similar mechanism offers high tribological resistance to hard films on soft, flexible polymers, which is shown for diamond-like carbon (DLC) and titanium nitride thin films on ultrasoft polyurethane and harder polycarbonate substrates. The choice of these two compared substrate materials will show that ultra-soft substrate materials are decisive for the distinct tribological material. Hierarchical wrinkled structures of films on these substrates are due to high intrinsic compressive stress, which evolves during high energetic film growth. Incremental relaxation of these stresses occurs by compound deformation of film and elastic substrate surface, appearing in hierarchical nano-wrinkles. Nano-wrinkled topographies enable high elastic deformability of thin hard films, while overstressing results in zigzag film fracture along larger hierarchical wrinkle structures. Tribologically, these fracture mechanisms are highly important for ploughing and sliding of sharp and flat counterparts on hard-coated ultra-soft substrates like polyurethane. Concentration of polyurethane deformation under the applied normal loads occurs below these zigzag cracks. Unloading closes these cracks again. Even cyclic testing do not lead to film delamination and retain low friction behavior, if the adhesion to the substrate is high and the initial friction coefficient of the film against the sliding counterpart low, e.g. found for DLC. PMID:24688710

  13. Colloidal-based additive manufacturing of bio-inspired composites

    NASA Astrophysics Data System (ADS)

    Studart, Andre R.

    Composite materials in nature exhibit heterogeneous architectures that are tuned to fulfill the functional demands of the surrounding environment. Examples range from the cellulose-based organic structure of plants to highly mineralized collagen-based skeletal parts like bone and teeth. Because they are often utilized to combine opposing properties such as strength and low-density or stiffness and wear resistance, the heterogeneous architecture of natural materials can potentially address several of the technical limitations of artificial homogeneous composites. However, current man-made manufacturing technologies do not allow for the level of composition and fiber orientation control found in natural heterogeneous systems. In this talk, I will present two additive manufacturing technologies recently developed in our group to build composites with exquisite architectures only rivaled by structures made by living organisms in nature. Since the proposed techniques utilize colloidal suspensions as feedstock, understanding the physics underlying the stability, assembly and rheology of the printing inks is key to predict and control the architecture of manufactured parts. Our results will show that additive manufacturing routes offer a new exciting pathway for the fabrication of biologically-inspired composite materials with unprecedented architectures and functionalities.

  14. Bio-Inspired Chemical Fabrication of Stretchable Transparent Electrodes.

    PubMed

    Yu, You; Zhang, Yaokang; Li, Kan; Yan, Casey; Zheng, Zijian

    2015-07-01

    Stretchable and transparent electrodes are fabricated by chemical deposition of metal thin films on natural veins of leaves at ambient conditions. These vein-based transparent electrodes show excellent electro-optical property (0.9 Ω sq(-1) at 83% T) even at 50% tensile strains, ideal for flexible and stretchable optoelectronic devices. PMID:25786920

  15. Bio-inspired artificial cilia with magnetic dynamic properties

    NASA Astrophysics Data System (ADS)

    Sun, Leilei; Zheng, Yongmei

    2015-04-01

    Inspired by the structure and properties of natural cilia, we focused on a facile template-free approach to prepare magnetic artificial cilia grown on the substrate (glass, PDMS, or others). In an applied magnetic field, the cilia formed spontaneously and immediately from magnetic nanoparticles and elastomeric polymer in a liquid solvent by bottom-up self-assembly. The length of prepared cilia could be in the scale of millimeter and reach a high aspect ratio of even over 100. We studied the effect of the magnetic strength applied and the size of nanoparticles to get tunable scale of cilia. The cilia show reversibly bending in an external magnetic field and this bending actuation gave some important functions: to transport macroscopic nonmagnetic materials on the cilia and to mix liquids.

  16. The role of bio-inspired hierarchical structures in wetting.

    PubMed

    Grewal, H S; Cho, Il-Joo; Yoon, Eui-Sung

    2015-04-01

    Superhydrophobicity facilitates the development of self-cleaning, anti-biofouling, and anti-corrosion surfaces. The leaves of the lotus (Nelumbo nucifera) and taro (Colocasia esculenta) plants are well known for their self-cleaning properties. A hierarchical structure comprising papillae epidermal cells superimposed with epicuticular wax crystalloids of varying shapes, sizes, and orientations is an important aspect of the surface of these plant leaves. We fabricated two types of hierarchical structures biomimicking the surface topography of the lotus leaf. The hierarchical patterns successfully demonstrated the superhydrophobic state in comparison with nano and micro patterns. We used the finite element method (FEM) to simulate and understand the wetting process. The FEM simulations showed good correlation with the experimental results. FEM was helpful in understanding the wetting of enormously complex biological surfaces with relative ease, and it qualifies as a potential tool for designing superhydrophobic surfaces. Using the FEM framework, we further designed surfaces to optimize the order of the shapes in hierarchy. The results showed that the superhydrophobic surface with the lowest wetted area was obtained by placing shapes with smaller geometric angles at the top of the hierarchy. This arrangement of shapes provides the optimum combination of superhydrophobicity and surface integrity. This observation explains why the hierarchical structure of many superhydrophobic leaves follows this order. We also investigated the complex hierarchical structure of Salvinia minima. Owing to its remarkable ability to entrap air and pin the contact line, it exhibits superhydrophobicity along with the much-required Cassie state. These properties of Salvinia minima make it an excellent candidate for developing omniphobic surfaces. PMID:25856043

  17. Bio-inspired homogeneous multi-scale place recognition.

    PubMed

    Chen, Zetao; Lowry, Stephanie; Jacobson, Adam; Hasselmo, Michael E; Milford, Michael

    2015-12-01

    Robotic mapping and localization systems typically operate at either one fixed spatial scale, or over two, combining a local metric map and a global topological map. In contrast, recent high profile discoveries in neuroscience have indicated that animals such as rodents navigate the world using multiple parallel maps, with each map encoding the world at a specific spatial scale. While a number of theoretical-only investigations have hypothesized several possible benefits of such a multi-scale mapping system, no one has comprehensively investigated the potential mapping and place recognition performance benefits for navigating robots in large real world environments, especially using more than two homogeneous map scales. In this paper we present a biologically-inspired multi-scale mapping system mimicking the rodent multi-scale map. Unlike hybrid metric-topological multi-scale robot mapping systems, this new system is homogeneous, distinguishable only by scale, like rodent neural maps. We present methods for training each network to learn and recognize places at a specific spatial scale, and techniques for combining the output from each of these parallel networks. This approach differs from traditional probabilistic robotic methods, where place recognition spatial specificity is passively driven by models of sensor uncertainty. Instead we intentionally create parallel learning systems that learn associations between sensory input and the environment at different spatial scales. We also conduct a systematic series of experiments and parameter studies that determine the effect on performance of using different neural map scaling ratios and different numbers of discrete map scales. The results demonstrate that a multi-scale approach universally improves place recognition performance and is capable of producing better than state of the art performance compared to existing robotic navigation algorithms. We analyze the results and discuss the implications with respect to several recent discoveries and theories regarding how multi-scale neural maps are learnt and used in the mammalian brain. PMID:26576467

  18. Bio-inspired magnetic swimming microrobots for biomedical applications

    NASA Astrophysics Data System (ADS)

    Peyer, Kathrin E.; Zhang, Li; Nelson, Bradley J.

    2013-01-01

    Microrobots have been proposed for future biomedical applications in which they are able to navigate in viscous fluidic environments. Nature has inspired numerous microrobotic locomotion designs, which are suitable for propulsion generation at low Reynolds numbers. This article reviews the various swimming methods with particular focus on helical propulsion inspired by E. coli bacteria. There are various magnetic actuation methods for biomimetic and non-biomimetic microrobots, such as rotating fields, oscillating fields, or field gradients. They can be categorized into force-driven or torque-driven actuation methods. Both approaches are reviewed and a previous publication has shown that torque-driven actuation scales better to the micro- and nano-scale than force-driven actuation. Finally, the implementation of swarm or multi-agent control is discussed. The use of multiple microrobots may be beneficial for in vivo as well as in vitro applications. Thus, the frequency-dependent behavior of helical microrobots is discussed and preliminary experimental results are presented showing the decoupling of an individual agent within a group of three microrobots.

  19. Bio-inspired microstructures in collagen type I hydrogel.

    PubMed

    Hosseini, Yahya; Verbridge, Scott S; Agah, Masoud

    2015-06-01

    This article presents a novel technique to fabricate complex type I collagen hydrogel structures, with varying depth and width defined by a single fabrication step. This technique takes advantage of reactive ion etching lag to fabricate three-dimensional (3-D) structures in silicon. Then, a polydimethylsiloxane replica was fabricated utilizing soft lithography and used as a stamp on collagen hydrogel to transfer these patterns. Endothelial cells were seeded on the hydrogel devices to measure their interaction with these more physiologically relevant cell culture surfaces. Confocal imaging was utilized to image the hydrogel devices to demonstrate the robustness of the fabrication technique, and to study the cell-extracellular matrix interaction after cell seeding. In this study, we observed that endothelial cells remodeled the sharp scallops of collagen hydrogel structures and compressed the structures with low degree of slope. Such patterning techniques will enhance the physiological relevance of existing 3-D cell culture platforms by providing a technical bridge between the high resolution yet planar techniques of standard lithography with more complex yet low resolution 3-D printing methods. PMID:25346472

  20. Bio-inspired wooden actuators for large scale applications.

    PubMed

    Rüggeberg, Markus; Burgert, Ingo

    2015-01-01

    Implementing programmable actuation into materials and structures is a major topic in the field of smart materials. In particular the bilayer principle has been employed to develop actuators that respond to various kinds of stimuli. A multitude of small scale applications down to micrometer size have been developed, but up-scaling remains challenging due to either limitations in mechanical stiffness of the material or in the manufacturing processes. Here, we demonstrate the actuation of wooden bilayers in response to changes in relative humidity, making use of the high material stiffness and a good machinability to reach large scale actuation and application. Amplitude and response time of the actuation were measured and can be predicted and controlled by adapting the geometry and the constitution of the bilayers. Field tests in full weathering conditions revealed long-term stability of the actuation. The potential of the concept is shown by a first demonstrator. With the sensor and actuator intrinsically incorporated in the wooden bilayers, the daily change in relative humidity is exploited for an autonomous and solar powered movement of a tracker for solar modules. PMID:25835386

  1. Bio-inspired magnetic swimming microrobots for biomedical applications.

    PubMed

    Peyer, Kathrin E; Zhang, Li; Nelson, Bradley J

    2013-02-21

    Microrobots have been proposed for future biomedical applications in which they are able to navigate in viscous fluidic environments. Nature has inspired numerous microrobotic locomotion designs, which are suitable for propulsion generation at low Reynolds numbers. This article reviews the various swimming methods with particular focus on helical propulsion inspired by E. coli bacteria. There are various magnetic actuation methods for biomimetic and non-biomimetic microrobots, such as rotating fields, oscillating fields, or field gradients. They can be categorized into force-driven or torque-driven actuation methods. Both approaches are reviewed and a previous publication has shown that torque-driven actuation scales better to the micro- and nano-scale than force-driven actuation. Finally, the implementation of swarm or multi-agent control is discussed. The use of multiple microrobots may be beneficial for in vivo as well as in vitro applications. Thus, the frequency-dependent behavior of helical microrobots is discussed and preliminary experimental results are presented showing the decoupling of an individual agent within a group of three microrobots. PMID:23165991

  2. Bio-Inspired Miniature Direction Finding Acoustic Sensor

    PubMed Central

    Wilmott, Daniel; Alves, Fabio; Karunasiri, Gamani

    2016-01-01

    A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. Thus, the directional response of the sensor is symmetric about the normal axis making the determination of the direction ambiguous. To overcome this shortcoming two sensors were assembled with a canted angle similar to that employed in radar bearing locators. The outputs of two sensors were processed together allowing direction finding with no requirement of knowing the incident sound pressure level. At the bending resonant frequency of the sensors (1.69 kHz) an output voltage of about 25 V/Pa was measured. The angle uncertainty of the bearing of sound ranged from less than 0.3° close to the normal axis (0°) to 3.4° at the limits of coverage (±60°) based on the 30° canted angle used. These findings indicate the great potential to use dual MEMS direction finding sensor assemblies to locate sound sources with high accuracy. PMID:27440657

  3. A Bio-Inspired Catalyst for CO2 Reduction

    NASA Astrophysics Data System (ADS)

    Bovell, Adonis; Warncke, Kurt

    2009-11-01

    Efficient storage of solar energy is critical for the next generation of solar energy conversion systems. Herein is described a catalytic module, using the robust TIM barrel fold of the EutB subunit of ethanolamine-ammonia lyase (EAL), for high specificity recognition and light-driven reduction of CO2 to energy rich biofuels. EAL catalyzes the deamination of ethanolamine via a free radical mechanism, by using an adenosylcobalamin (AdoCbl) cofactor. Our aim is to use the reducing power of the cobalt(I) form of the cofactor to drive the reduction of CO2. Molecular biology techniques have been used to generate histidine-tagged EutB subunits of EAL for high throughput protein purification. The binding of cobalamins to EutB was probed by using tryptophan fluorescence quenching. The Hill constant (KH) and coefficient (nH) for AdoCbl-EutB binding were determined as 33 μM and 1.3, respectively. The results show that cob(III)alamin binds to isolated EutB, and suggest that Co(II) and Co(I) states will also bind. Rational active site modifications of EutB will be made to facilitate specific CO2-Co(I) binding and to introduce a proton delivery network. The results will give insight into the challenging task of rational enzyme design.

  4. Bio-Inspired Catalyst for CO2 Reduction

    NASA Astrophysics Data System (ADS)

    Bovell, Adonis; Warncke, Kurt

    2010-03-01

    A catalytic device for high specificity recognition and light-driven reduction of CO2 to energy rich biofuels is being developed by using the robust TIM barrel fold of the EutB subunit of the enzyme, ethanolamine-ammonia lyase (from Salmonella typhimurium), as a scaffold. The cobalt(I) form of the native cobalamin serves as the catalytic center. Results show that cobalamins bind with optimal micromolar affinity to purified EutB, and undergo reductive activation. Molecular biology techniques have been used to generate histidine-tagged EutB subunit for high throughput mutagenesis studies. Rational active site modifications of EutB have been made to satisfy the criteria of specific CO2 binding, reduction, and proton delivery.

  5. Bio-inspired diversity for increasing attacker workload

    NASA Astrophysics Data System (ADS)

    Kuhn, Stephen

    2014-05-01

    Much of the traffic in modern computer networks is conducted between clients and servers, rather than client-toclient. As a result, servers represent a high-value target for collection and analysis of network traffic. As they reside at a single network location (i.e. IP/MAC address) for long periods of time. Servers present a static target for surveillance, and a unique opportunity to observe the network traffic. Although servers present a heightened value for attackers, the security community as a whole has shifted more towards protecting clients in recent years leaving a gap in coverage. In addition, servers typically remain active on networks for years, potentially decades. This paper builds on previous work that demonstrated a proof of concept leveraging existing technology for increasing attacker workload. Here we present our clean slate approach to increasing attacker workload through a novel hypervisor and micro-kernel, utilizing next generation virtualization technology to create synthetic diversity of the server's presence including the hardware components.

  6. Bio-inspired Propulsion with Functionally Graded Materials

    NASA Astrophysics Data System (ADS)

    Schleicher, William; Floryan, Daniel; van Buren, Tyler; Smits, Alexander; Moored, Keith; Lehigh University Team; Priceton University Team

    2015-11-01

    From an engineering perspective, biological swimmers are a composite material system with varying material properties across their propulsors. These material properties govern how the swimmer's structure interacts with its surrounding fluid. A two dimensional boundary element fluid solver is strongly coupled to a direct, implicit, geometrically non-linear structure solver to study the effects of functionally graded materials. A zeroth order functionally graded material approximation is used, where a rigid material abruptly meets a flexible material. Thrust, input power, and propulsive efficiency are studied as functions of non-dimensional frequency, reduced frequency, Strouhal number, flexion ratio, and effective stiffness. The numerical results are compared to experimental results for zero attack angle cases, building confidence in the numerical model. The results are further compared to structurally rigid materials. Supported by the Office of Naval Research under Program Director Dr. Bob Brizzolara, MURI grant number N00014-14-1-0533.

  7. Bio-Inspired Miniature Direction Finding Acoustic Sensor

    NASA Astrophysics Data System (ADS)

    Wilmott, Daniel; Alves, Fabio; Karunasiri, Gamani

    2016-07-01

    A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. Thus, the directional response of the sensor is symmetric about the normal axis making the determination of the direction ambiguous. To overcome this shortcoming two sensors were assembled with a canted angle similar to that employed in radar bearing locators. The outputs of two sensors were processed together allowing direction finding with no requirement of knowing the incident sound pressure level. At the bending resonant frequency of the sensors (1.69 kHz) an output voltage of about 25 V/Pa was measured. The angle uncertainty of the bearing of sound ranged from less than 0.3° close to the normal axis (0°) to 3.4° at the limits of coverage (±60°) based on the 30° canted angle used. These findings indicate the great potential to use dual MEMS direction finding sensor assemblies to locate sound sources with high accuracy.

  8. Bio-Inspired Miniature Direction Finding Acoustic Sensor.

    PubMed

    Wilmott, Daniel; Alves, Fabio; Karunasiri, Gamani

    2016-01-01

    A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. Thus, the directional response of the sensor is symmetric about the normal axis making the determination of the direction ambiguous. To overcome this shortcoming two sensors were assembled with a canted angle similar to that employed in radar bearing locators. The outputs of two sensors were processed together allowing direction finding with no requirement of knowing the incident sound pressure level. At the bending resonant frequency of the sensors (1.69 kHz) an output voltage of about 25 V/Pa was measured. The angle uncertainty of the bearing of sound ranged from less than 0.3° close to the normal axis (0°) to 3.4° at the limits of coverage (±60°) based on the 30° canted angle used. These findings indicate the great potential to use dual MEMS direction finding sensor assemblies to locate sound sources with high accuracy. PMID:27440657

  9. Behavior of an adaptive bio-inspired spider web

    NASA Astrophysics Data System (ADS)

    Zheng, Lingyue; Behrooz, Majid; Huie, Andrew; Hartman, Alex; Gordaninejad, Faramarz

    2015-03-01

    The goal of this study is to demonstrate the feasibility of an artificial adaptive spider web with comparable behavior to a real spider web. First, the natural frequency and energy absorption ability of a passive web is studied. Next, a control system that consists of stepper motors, load cells and an Arduino, is constructed to mimic a spider's ability to control the tension of radial strings in the web. The energy related characteristics in the artificial spider web is examined while the pre-tension of the radial strings are varied. Various mechanical properties of a damaged spider web are adjusted to study their effect on the behavior of the web. It is demonstrated that the pre-tension and stiffness of the web's radial strings can significantly affect the natural frequency and the total energy of the full and damaged webs.

  10. A Bio-Inspired Electromechanical System: Artificial Hair Cell

    NASA Astrophysics Data System (ADS)

    Ahn, Kang-Hun

    Inspired by recent biophysical study on the auditory sensory organs, we study electromechanical system which functions similar to the hair cell of the ear. One of the important mechanisms of hair cells, adaptation, is mimicked by an electromechanical feedback loop. The proposed artificial hair cell functions similar to a living sensory organ in the sense that it senses input force signal in spite of the relatively strong noise. Numerical simulation of the proposed system shows otoacoustic sound emission, which was observed in the experiments on the hair cells of the bullfrog. This spontaneous motion is noise-induced periodic motion which is controlled by the time scale of adaptation process and the mechanical damping.

  11. Polyelectrolytes in the synthesis of bio-inspired composite materials

    NASA Astrophysics Data System (ADS)

    McKenna, Brandon J.

    2007-05-01

    This original research dissertation contains studies on complex coacervation, methods of modifying coacervates to create new materials as particularly applied to targeted drug delivery, and the use of coacervating polyanions for the assembly of intricate structures of calcium carbonate. Complex coacervation is a liquid-liquid phase separation that typically produces microspherical droplets from the combination of a variety of oppositely charged ions, including polymers and nanoparticles. The chemical space of coacervating components was found dependent on the number of charged groups and pH. Coacervates were shown to present chemically active surfaces that could be solidified by various methods, some of which also induced hollow interiors. The resulting assemblies were considered for targeted drug delivery by using superparamagnetic magnetite nanoparticles as assembling components. Control over microsphere sizes was obtained from variation of several parameters, and porosities were examined as a function of cross-linking extent to determine encapsulation capabilities. Coacervates were further found to direct mineral growth, first in the form of shells, and then in the form of complicated structures that require substrate interaction via a solution-amorphous-crystalline mechanism. A ternary phase diagram approach revealed a great diversity of morphologies that could be modulated by the action of coacervating polyanions. Detailed analysis of one particular stacked lamellar structure suggested an assembly mechanism that may have relevance for biomineralization of nacre.

  12. Nanophotonics of Chloroplasts for Bio-Inspired Solar Energy Materials

    NASA Astrophysics Data System (ADS)

    Gourley, Paul L.; Gourley, Cheryl R.

    2011-03-01

    In the search for new energy sources, lessons can be learned from chloroplast photonics. The nano-architecture of chloroplasts is remarkably well-adapted to mediate sunlight interactions for efficient energy conversion. We carried out experiments with chloroplasts isolated from spinach and leaf lettuce to elucidate the relationship between nano-architecture, biomolecular composition and photonic properties. We obtained high-resolution microscopic images of single chloroplasts to identify geometries of chloroplasts and interior grana. We performed micro-spectroscopy to identify strengths of absorption and fluorescence transitions and related them to broadband reflectance and transmittance spectra of whole leaf structures. Finally, the nonlinear optical properties were investigated with nanolaser spectroscopy by placing chloroplasts into micro-resonators and optically pumping. These spectra reveal chloroplast photonic modes and allow measurement of single chloroplast light scattering cross section, polarizability, and refractive index. The nanolaser spectra recorded at increasing pump powers enabled us to observe non-linear optics, photon dynamics, and stimulated emission from single chloroplasts. All of these experiments provide insight into plant photonics and inspiration of paradigms for synthetic biomaterials to harness sunlight in new ways.

  13. Bio-inspired interfacial strengthening strategy through geometrically interlocking designs.

    PubMed

    Zhang, Yuming; Yao, Haimin; Ortiz, Christine; Xu, Jinquan; Dao, Ming

    2012-11-01

    Many biological materials, such as nacre and bone, are hybrid materials composed of stiff brittle ceramics and compliant organic materials. These natural organic/inorganic composites exhibit much enhanced strength and toughness in comparison to their constituents and inspires enormous biomimetic endeavors aiming to synthesize materials with superior mechanical properties. However, most current synthetic composites have not exhibited their full potential of property enhancement compared to the natural prototypes they are mimicking. One of the key issues is the weak junctions between stiff and compliant phases, which need to be optimized according to the intended functions of the composite material. Motivated by the geometrically interlocking designs of natural biomaterials, here we propose an interfacial strengthening strategy by introducing geometrical interlockers on the interfaces between compliant and stiff phases. Finite element analysis (FEA) shows that the strength of the composite depends strongly on the geometrical features of interlockers including shape, size, and structural hierarchy. Even for the most unfavorable scenario when neither adhesion nor friction is present between stiff and compliant phases, the tensile strength of the composites with proper interlocker design can reach up to 70% of the ideal value. The findings in this paper would provide guidelines to the improvement of the mechanical properties of current biomimetic composites. PMID:23032427

  14. Microfabrication of IPMC cilia for bio-inspired flow sensing

    NASA Astrophysics Data System (ADS)

    Lei, Hong; Li, Wen; Tan, Xiaobo

    2012-04-01

    As the primary flow sensing organ for fishes, the lateral line system plays a critical role in fish behavior. Analogous to its biological counterpart, an artificial lateral line system, consisting of arrays of micro flow sensors, is expected to be instrumental in the navigation and control of underwater robots. In this paper we investigate the microfabrication of ionic polymer-metal composite (IPMC) cilia for the purpose of flow sensing. While existing macro- and microfabrication methods for IPMCs have predominantly focused on planar structures, we propose a device where micro IPMC beams stand upright on a substrate to effectively interact with the flow. Challenges in the casting of 3D Nafion structure and selective formation of electrodes are discussed, and potential solutions for addressing these challenges are presented together with preliminary microfabrication results.

  15. Bio-inspired adhesion: local chemical environments impact adhesive stability

    NASA Astrophysics Data System (ADS)

    Gebbie, Matthew A.; Rapp, Michael V.; Yu, Jing; Wei, Wei; Waite, J. Herbert; Israelachvili, Jacob N.

    2014-03-01

    3,4-dihydroxyphenylalanine (Dopa) is an amino acid that is naturally synthesized by marine mussels and exhibits the unique ability to strongly bind to surfaces in aqueous environments. However, the Dopa functional group undergoes auto-oxidation to a non-adhesive quinone form in neutral to basic pH conditions, limiting the utilization of Dopa in biomedical applications. In this work, we performed direct surface force measurements with in situ electrochemical control across a Dopa-rich native mussel foot protein (mfp-5), as well as three simplified model peptide sequences. We find that the neighboring peptide residues can significantly impact the redox stability of Dopa functional groups, with lysine residues imparting a substantial degree of Dopa redox stabilization. Surprisingly, the local chemical environments only minimally impact the magnitude of the adhesion forces measured between molecularly-smooth mica and gold surfaces. Our results provide molecular level insight into approaches that can be used to mitigate the detrimental impact of Dopa auto-oxidation, thus suggesting new molecular design strategies for improving the performance of Dopa-based underwater adhesives.

  16. Bio-Inspired Wooden Actuators for Large Scale Applications

    PubMed Central

    Rüggeberg, Markus; Burgert, Ingo

    2015-01-01

    Implementing programmable actuation into materials and structures is a major topic in the field of smart materials. In particular the bilayer principle has been employed to develop actuators that respond to various kinds of stimuli. A multitude of small scale applications down to micrometer size have been developed, but up-scaling remains challenging due to either limitations in mechanical stiffness of the material or in the manufacturing processes. Here, we demonstrate the actuation of wooden bilayers in response to changes in relative humidity, making use of the high material stiffness and a good machinability to reach large scale actuation and application. Amplitude and response time of the actuation were measured and can be predicted and controlled by adapting the geometry and the constitution of the bilayers. Field tests in full weathering conditions revealed long-term stability of the actuation. The potential of the concept is shown by a first demonstrator. With the sensor and actuator intrinsically incorporated in the wooden bilayers, the daily change in relative humidity is exploited for an autonomous and solar powered movement of a tracker for solar modules. PMID:25835386

  17. Bio-Inspired Microsystem for Robust Genetic Assay Recognition

    PubMed Central

    Lue, Jaw-Chyng; Fang, Wai-Chi

    2008-01-01

    A compact integrated system-on-chip (SoC) architecture solution for robust, real-time, and on-site genetic analysis has been proposed. This microsystem solution is noise-tolerable and suitable for analyzing the weak fluorescence patterns from a PCR prepared dual-labeled DNA microchip assay. In the architecture, a preceding VLSI differential logarithm microchip is designed for effectively computing the logarithm of the normalized input fluorescence signals. A posterior VLSI artificial neural network (ANN) processor chip is used for analyzing the processed signals from the differential logarithm stage. A single-channel logarithmic circuit was fabricated and characterized. A prototype ANN chip with unsupervised winner-take-all (WTA) function was designed, fabricated, and tested. An ANN learning algorithm using a novel sigmoid-logarithmic transfer function based on the supervised backpropagation (BP) algorithm is proposed for robustly recognizing low-intensity patterns. Our results show that the trained new ANN can recognize low-fluorescence patterns better than an ANN using the conventional sigmoid function. PMID:18566679

  18. Bio-inspired propulsor using internally powered flexible fins

    NASA Astrophysics Data System (ADS)

    Yeh, Peter; Erturk, Alper; Alexeev, Alexander

    2014-11-01

    Using experiments and three dimensional numerical simulations, we study the underwater locomotion of internally powered flexible plates. The flexible plate is composed of Macro-Fiber Composite (MFC) piezoelectric laminates. A sinusoidally varying voltage is applied to the MFCs, causing bending and generating thrust similar to a flapping fin in carangiform motion. In our fully coupled FSI simulations, we model the swimmer as a rectangular elastic plate actuated by a sinusoidal internal moment. The steady state swimming velocity and thrust are measured experimentally and compared to our numerical simulations. Our results can be used to design underwater self-propelling vehicles driven by internally powered flexible fins.

  19. Bio-inspired cisplatin nanocarriers for osteosarcoma treatment.

    PubMed

    Zhou, Haidong; Wang, Gangxiang; Lu, Yiyun; Pan, Zhijun

    2016-08-19

    In this study, cisplatin (cis-diaminedichloroplatinum, CDDP) nanocarriers with phosphorylcholine surface tailoring were developed to enhance the anti-tumor potential of CDDP for the treatment of osteosarcoma. Poly(2-methacryloyloxyethyl phosphorylcholine)-b-poly(methacrylic acid) (PMPC-b-PMAA) was synthesized for the preparation of CDDP/PMPC-b-PMAA micelles. The synthesis, self-assembly, and in vitro drug release were well characterized. In vitro cytotoxicity showed that CDDP/PMPC-b-PMAA micelles can strongly inhibit the proliferation of Saos-2 cells. In vivo experiments indicated that CDDP/PMPC-b-PMAA micelles showed prolonged circulation time, reduced renal accumulation, and enhanced tumor accumulation compared to free CDDP. Overall, the CDDP/PMPC-b-PMAA micelles exhibited optimal anti-tumor activity with minimal side effects in the treatment of osteosarcoma. PMID:27315174

  20. Bio-inspired MOF-based Catalysts for Lignin Valorization.

    SciTech Connect

    Allendorf, Mark D.; Stavila, Vitalie; Ramakrishnan, Parthasarathi; Davis, Ryan Wesley

    2014-09-01

    Lignin is a potentially plentiful source of renewable organics, with %7E50Mtons/yr produced by the pulp/paper industry and 200-300 Mtons/yr projected production by a US biofuels industry. This industry must process approximately 1 billion tons of biomass to meet the US Renewable Fuel goals. However, there are currently no efficient processes for converting lignin to value-added chemicals and drop-in fuels. Lignin is therefore an opportunity for production of valuable renewable chemicals, but presents staggering technical and economic challenges due to the quantities of material involved and the strong chemical bonds comprising this polymer. Aggressive chemistries and high temperatures are required to degrade lignin without catalysts. Moreover, chemical non-uniformity among lignins leads to complex product mixtures that tend to repolymerize. Conventional petrochemical approaches (pyrolysis, catalytic cracking, gasification) are energy intensive (400-800 degC), require complicated separations, and remove valuable chemical functionality. Low-temperature (25-200 degC) alternatives are clearly desirable, but enzymes are thermally fragile and incompatible with liquid organic compounds, making them impractical for large-scale biorefining. Alternatively, homogeneous catalysts, such as recently developed vanadium complexes, must be separated from product mixtures, while many heterogenous catalysts involve costly noble metals. The objective of this project is to demonstrate proof of concept that an entirely new class of biomimetic, efficient, and industrially robust synthetic catalysts based on nanoporous Metal- Organic Frameworks (MOFs) can be developed. Although catalytic MOFs are known, catalysis of bond cleavage reactions needed for lignin degradation is completely unexplored. Thus, fundamental research is required that industry and most sponsoring agencies are currently unwilling to undertake. We introduce MOFs infiltrated with titanium and nickel species as catalysts for the C-O bond hydrogenolysis in model compounds, which mimic the b-O-4, a-O-4, and 4-O-5 linkages of natural lignin. The versatile IRMOF-74(n) series is proposed as a platform for creating efficient hydrogenolysis catalysts as it not only displays tunable pore sizes, but also has the required thermal and chemical stability. The catalytic C-O bond cleavage occurs at 10 bar hydrogen pressure and temperatures as low as 120 degC. The conversion efficiency of the aromatic ether substrates into the corresponding hydrocarbons and phenols varies as PhCH 2 CH 2 OPh > PhCH 2 OPh > PhOPh (Ph = phenyl), while the catalytic activity generally follows the following trend Ni@IRMOF-74>Ti@IRMOF-74>IRMOF-74. Conversions as high as 80%, coupled with good selectivity for hydrogenolysis vs. hydrogenation, highlight the potential of MOF-based catalysts for the selective cleavage of recalcitrant aryl-ether bonds found in lignin and other biopolymers. This project supports the DOE Integrated Biorefinery Program goals, the objective of which is to convert biomass to fuels and high-value chemicals, by addressing an important technology gap: the lack of low-temperature catalysts suitable for industrial lignin degradation. Biomass, which is %7E30 wt% lignin, constitutes a potentially major source of platform chemicals that could improve overall profitability and productivity of all energy-related products, thereby benefiting consumers and reducing national dependence on imported oil. Additionally, DoD has a strong interest in low-cost drop-in fuels (Navy Biofuel Initiative) and has signed a Memorandum of Understanding with DOE and USDA to develop a sustainable biofuels industry.

  1. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives

    PubMed Central

    2015-01-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm2 provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  2. Bio-inspired robotic legs drive viscous recirculating flows

    NASA Astrophysics Data System (ADS)

    Takagi, Daisuke; Hayashi, Rintaro

    2015-11-01

    Crustaceans actuate multiple legs in a well-coordinated sequence to generate suitable flow for feeding and swimming. Inspired by tiny crustacean larvae operating at low Reynolds number, we study a scaled-up model in which slender rods oscillate independently in a bath of glycerol. Experiments reveal qualitatively different flow patterns depending on the phase and orientation of actuated rods. The observations are analyzed in the framework of slender-body theory for Stokes flow. This study shows that simple oscillatory motion of multiple legs can produce complex recirculating flows, with potential applications for mixing and pumping.

  3. Effect of agitation and terminal subcultures on yield and speed of detection of the Oxoid Signal blood culture system versus the BACTEC radiometric system

    SciTech Connect

    Weinstein, M.P.; Mirrett, S.; Reimer, L.G.; Reller, L.B.

    1989-03-01

    In an initial evaluation, we found the Oxoid Signal blood culture system inferior to the BACTEC radiometric system for detection of some microorganisms causing septicemia. To determine whether modified processing of the Oxoid Signal blood culture system could improve its yield and speed of detecting positive cultures relative to the BACTEC radiometric system, we agitated all Oxoid bottles during the first 24 to 48 h of incubation and performed aerobic and anaerobic subcultures of all Oxoid bottles negative after 7 days of incubation. These modifications improved the overall performance of the Oxoid system, particularly with regard to the yield of streptococci, members of the family Enterobacteriaceae, and Haemophilus, Neisseria, and Acinetobacter spp. The speed of detecting positive cultures also was improved, especially within the first 24 h of incubation. However, the BACTEC system still detected more positive cultures (P less than 0.005), especially of obligate aerobes such as Pseudomonas aeruginosa (P less than 0.05) and yeasts (P less than 0.005). The BACTEC system also detected positive cultures earlier than the Oxoid system (e.g., at 24 h of incubation, 70.5% of BACTEC positive cultures detected versus 62.1% of Oxoid positive cultures detected). Further modifications of the Oxoid system which might include a revised medium, additional processing modifications, altered headspace atmosphere, or a complementary second broth medium should be considered, since the system is attractive in concept and is easy to use in the clinical laboratory.

  4. High-Speed Scanning Interferometer Using CMOS Image Sensor and FPGA Based on Multifrequency Phase-Tracking Detection

    NASA Technical Reports Server (NTRS)

    Ohara, Tetsuo

    2012-01-01

    A sub-aperture stitching optical interferometer can provide a cost-effective solution for an in situ metrology tool for large optics; however, the currently available technologies are not suitable for high-speed and real-time continuous scan. NanoWave s SPPE (Scanning Probe Position Encoder) has been proven to exhibit excellent stability and sub-nanometer precision with a large dynamic range. This same technology can transform many optical interferometers into real-time subnanometer precision tools with only minor modification. The proposed field-programmable gate array (FPGA) signal processing concept, coupled with a new-generation, high-speed, mega-pixel CMOS (complementary metal-oxide semiconductor) image sensor, enables high speed (>1 m/s) and real-time continuous surface profiling that is insensitive to variation of pixel sensitivity and/or optical transmission/reflection. This is especially useful for large optics surface profiling.

  5. Evaluation of Pressure Stable Chip-to-Tube Fittings Enabling High-Speed Chip-HPLC with Mass Spectrometric Detection.

    PubMed

    Lotter, Carsten; Heiland, Josef J; Stein, Volkmar; Klimkait, Michael; Queisser, Marco; Belder, Detlev

    2016-08-01

    Appropriate chip-to-tube interfacing is an enabling technology for high-pressure and high-speed liquid chromatography on chip. For this purpose, various approaches, to connect pressure resistant glass chips with HPLC pumps working at pressures of up to 500 bar, were examined. Three side-port and one top-port connection approach were evaluated with regard to pressure stability and extra column band broadening. A clamp-based top-port approach enabled chip-HPLC-MS analysis of herbicides at the highest pressure and speed. PMID:27397738

  6. Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control

    NASA Astrophysics Data System (ADS)

    McGovern, Scott; Alici, Gursel; Truong, Van-Tan; Spinks, Geoffrey

    2009-09-01

    This paper presents the development of an autonomously powered and controlled robotic fish that incorporates an active flexural joint tail fin, activated through conducting polymer actuators based on polypyrrole (PPy). The novel electromaterial muscle oscillator (NEMO) tail fin assembly on the fish could be controlled wirelessly in real time by varying the frequency and duty cycle of the voltage signal supplied to the PPy bending-type actuators. Directional control was achieved by altering the duty cycle of the voltage input to the NEMO tail fin, which shifted the axis of oscillation and enabled turning of the robotic fish. At low speeds, the robotic fish had a turning circle as small as 15 cm (or 1.1 body lengths) in radius. The highest speed of the fish robot was estimated to be approximately 33 mm s-1 (or 0.25 body lengths s-1) and was achieved with a flapping frequency of 0.6-0.8 Hz which also corresponded with the most hydrodynamically efficient mode for tail fin operation. This speed is approximately ten times faster than those for any previously reported artificial muscle based device that also offers real-time speed and directional control. This study contributes to previously published studies on bio-inspired functional devices, demonstrating that electroactive polymer actuators can be real alternatives to conventional means of actuation such as electric motors.

  7. Thermal iron ions in high speed solar wind streams Detection by the IMP 7/8 energetic particle experiments

    NASA Technical Reports Server (NTRS)

    Mitchell, D. G.; Roelof, E. C.

    1980-01-01

    The first measurements of the abundance of iron ions in high speed (greater than 600 km/s) solar wind streams have been made with the NOAA/JHU energetic particles experiments (EPE) on IMP 7/8. The identification of iron ions is quantitatively established using 4 years of observations and heavy ion accelerator calibrations of detectors similar to those flown on the spacecraft. Preliminary estimates of the Fe/H ratio are within a factor of 2 of the adopted coronal abundance (0.00005), and there is some evidence that Fe/H may remain approximately constant within a given stream. In the peaks of fast streams (700-800 km/s), about 50 iron ion counts are obtained every 20 s, offering the possibility of studying the Fe/H ratio with approximately 1 m time resolution in high speed streams throughout the decline of Solar Cycle 20 and the rise of Solar Cycle 21.

  8. Quadrupedal galloping control for a wide range of speed via vertical impulse scaling.

    PubMed

    Park, Hae-Won; Kim, Sangbae

    2015-04-01

    This paper presents a bio-inspired quadruped controller that allows variable-speed galloping. The controller design is inspired by observations from biological runners. Quadrupedal animals increase the vertical impulse that is generated by ground reaction forces at each stride as running speed increases and the duration of each stance phase reduces, whereas the swing phase stays relatively constant. Inspired by this observation, the presented controller estimates the required vertical impulse at each stride by applying the linear momentum conservation principle in the vertical direction and prescribes the ground reaction forces at each stride. The design process begins with deriving a planar model from the MIT Cheetah 2 robot. A baseline periodic limit cycle is obtained by optimizing ground reaction force profiles and the temporal gait pattern (timing and duration of gait phases). To stabilize the optimized limit cycle, the obtained limit cycle is converted to a state feedback controller by representing the obtained ground reaction force profiles as functions of the state variable, which is monotonically increasing throughout the gait, adding impedance control around the height and pitch trajectories of the obtained limit cycle and introducing a finite state machine and a pattern stabilizer to enforce the optimized gait pattern. The controller that achieves a stable 3 m s(-1) gallop successfully adapts the speed change by scaling the vertical ground reaction force to match the momentum lost by gravity and adding a simple speed controller that controls horizontal speed. Without requiring additional gait optimization processes, the controller achieves galloping at speeds ranging from 3 m s(-1) to 14.9 m s(-1) while respecting the torque limit of the motor used in the MIT Cheetah 2 robot. The robustness of the controller is verified by demonstrating stable running during various disturbances, including 1.49 m step down and 0.18 m step up, as well as random ground

  9. Speed and amplitude of lung tumor motion precisely detected in four-dimensional setup and in real-time tumor-tracking radiotherapy

    SciTech Connect

    Shirato, Hiroki . E-mail: hshirato@radi.med.hokudai.ac.jp; Suzuki, Keishiro; Sharp, Gregory C.; Fujita, Katsuhisa R.T.; Onimaru, Rikiya; Fujino, Masaharu; Kato, Norio; Osaka, Yasuhiro; Kinoshita, Rumiko; Taguchi, Hiroshi; Onodera, Shunsuke; Miyasaka, Kazuo

    2006-03-15

    Background: To reduce the uncertainty of registration for lung tumors, we have developed a four-dimensional (4D) setup system using a real-time tumor-tracking radiotherapy system. Methods and Materials: During treatment planning and daily setup in the treatment room, the trajectory of the internal fiducial marker was recorded for 1 to 2 min at the rate of 30 times per second by the real-time tumor-tracking radiotherapy system. To maximize gating efficiency, the patient's position on the treatment couch was adjusted using the 4D setup system with fine on-line remote control of the treatment couch. Results: The trajectory of the marker detected in the 4D setup system was well visualized and used for daily setup. Various degrees of interfractional and intrafractional changes in the absolute amplitude and speed of the internal marker were detected. Readjustments were necessary during each treatment session, prompted by baseline shifting of the tumor position. Conclusion: The 4D setup system was shown to be useful for reducing the uncertainty of tumor motion and for increasing the efficiency of gated irradiation. Considering the interfractional and intrafractional changes in speed and amplitude detected in this study, intercepting radiotherapy is the safe and cost-effective method for 4D radiotherapy using real-time tracking technology.

  10. Fiber optic sensor employing successively destroyed coupled points or reflectors for detecting shock wave speed and damage location

    DOEpatents

    Weiss, J.D.

    1995-08-29

    A shock velocity and damage location sensor providing a means of measuring shock speed and damage location is disclosed. The sensor consists of a long series of time-of-arrival ``points`` constructed with fiber optics. The fiber optic sensor apparatus measures shock velocity as the fiber sensor is progressively crushed as a shock wave proceeds in a direction along the fiber. The light received by a receiving means changes as time-of-arrival points are destroyed as the sensor is disturbed by the shock. The sensor may comprise a transmitting fiber bent into a series of loops and fused to a receiving fiber at various places, time-of-arrival points, along the receiving fibers length. At the ``points`` of contact, where a portion of the light leaves the transmitting fiber and enters the receiving fiber, the loops would be required to allow the light to travel backwards through the receiving fiber toward a receiving means. The sensor may also comprise a single optical fiber wherein the time-of-arrival points are comprised of reflection planes distributed along the fibers length. In this configuration, as the shock front proceeds along the fiber it destroys one reflector after another. The output received by a receiving means from this sensor may be a series of downward steps produced as the shock wave destroys one time-of-arrival point after another, or a nonsequential pattern of steps in the event time-of-arrival points are destroyed at any point along the sensor. 6 figs.

  11. Fiber optic sensor employing successively destroyed coupled points or reflectors for detecting shock wave speed and damage location

    DOEpatents

    Weiss, Jonathan D.

    1995-01-01

    A shock velocity and damage location sensor providing a means of measuring shock speed and damage location. The sensor consists of a long series of time-of-arrival "points" constructed with fiber optics. The fiber optic sensor apparatus measures shock velocity as the fiber sensor is progressively crushed as a shock wave proceeds in a direction along the fiber. The light received by a receiving means changes as time-of-arrival points are destroyed as the sensor is disturbed by the shock. The sensor may comprise a transmitting fiber bent into a series of loops and fused to a receiving fiber at various places, time-of-arrival points, along the receiving fibers length. At the "points" of contact, where a portion of the light leaves the transmitting fiber and enters the receiving fiber, the loops would be required to allow the light to travel backwards through the receiving fiber toward a receiving means. The sensor may also comprise a single optical fiber wherein the time-of-arrival points are comprised of reflection planes distributed along the fibers length. In this configuration, as the shock front proceeds along the fiber it destroys one reflector after another. The output received by a receiving means from this sensor may be a series of downward steps produced as the shock wave destroys one time-of-arrival point after another, or a nonsequential pattern of steps in the event time-of-arrival points are destroyed at any point along the sensor.

  12. Enhanced channel estimation and symbol detection for high speed multi-input multi-output underwater acoustic communications.

    PubMed

    Ling, Jun; Yardibi, Tarik; Su, Xiang; He, Hao; Li, Jian

    2009-05-01

    The need for achieving higher data rates in underwater acoustic communications leverages the use of multi-input multi-output (MIMO) schemes. In this paper two key issues regarding the design of a MIMO communications system, namely, channel estimation and symbol detection, are addressed. To enhance channel estimation performance, a cyclic approach for designing training sequences and a channel estimation algorithm called the iterative adaptive approach (IAA) are presented. Sparse channel estimates can be obtained by combining IAA with the Bayesian information criterion (BIC). Moreover, the RELAX algorithm can be used to improve the IAA with BIC estimates further. Regarding symbol detection, a minimum mean-squared error based detection scheme, called RELAX-BLAST, which is a combination of vertical Bell Labs layered space-time (V-BLAST) algorithm and the cyclic principle of the RELAX algorithm, is presented and it is shown that RELAX-BLAST outperforms V-BLAST. Both simulated and experimental results are provided to validate the proposed MIMO scheme. RACE'08 experimental results employing a 4 x 24 MIMO system show that the proposed scheme enjoys an average uncoded bit error rate of 0.38% at a payload data rate of 31.25 kbps and an average coded bit error rate of 0% at a payload data rate of 15.63 kbps. PMID:19425650

  13. Engine speed control apparatus

    SciTech Connect

    Ishii, M.; Miyazaki, M.; Nakamura, N.; Kakinuma, H.

    1986-11-04

    This patent describes an engine speed control apparatus. The system comprises an actuator for adjusting an engine speed, a first unit for computing a desired engine speed, a second unit for detecting the actual engine speed, and a third unit for detecting the difference between the outputs of the first and second units. The system also includes a fourth unit for computing a control pulse width for the actuator in accordance with the output of the third unit, a fifth unit for generating a control signal, a sixth unit for driving the actuator in response to the output of the fifth unit, and a seventh unit for computing an optimal halt time to interrupt the driving of the actuator. The actuator is driven intermittently in conformity in the control pulse width and the halt time.

  14. PREPARATIVE ISOLATION AND PURIFICATION OF THREE GLYCINE-CONJUGATED CHOLIC ACIDS FROM PULVIS FELLIS SUIS BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY COUPLED WITH ELSD DETECTION

    PubMed Central

    He, Jiao; Li, Jing; Sun, Wenji; Zhang, Tianyou; Ito, Yoichiro

    2011-01-01

    Coupled with evaporative light scattering detection, a high-speed counter-current chromatography (HSCCC) method was developed for preparative isolation and purification of three glycine-conjugated cholic acids, glycochenodeoxycholic acid (GCDCA), glycohyodeoxycholic acid (GHDCA) and glycohyocholic acid (GHCA) from Pulvis Fellis Suis (Pig gallbladder bile) for the first time. The separation was performed with a two-phase solvent system consisted of chloroform-methanol-water-acetic acid (65:30:10:1.5, v/v/v/v) by eluting the lower phase in the head-to-tail elution mode. The revolution speed of the separation column, flow rate of the mobile phase and separation temperature were 800 rpm, 2 ml/min and 25 °C, respectively. In a single operation, 33 mg of GCDCA, 38 mg of GHDCA and 23 mg of GHCA were obtained from 200 mg of crude extract with the purity of 95.65%, 96.72% and 96.63%, respectively, in one step separation. The HSCCC fractions were analyzed by high-performance liquid chromatography (HPLC) and the structures of the three glycine-conjugated cholic acids were identified by ESI-MS, 1H NMR and 13C NMR. PMID:23008527

  15. In vitro comparison of Kodak Ultra-speed, Ektaspeed, and Ektaspeed Plus, and Agfa M2 Comfort dental x-ray films for the detection of caries.

    PubMed

    Hintze, H; Christoffersen, L; Wenzel, A

    1996-02-01

    The aim of this study was to compare the diagnostic accuracy of two new dental x-ray films, Kodak Ektaspeed Plus (Plus) and Agfa M2 Comfort (M2), respectively, with the current Kodak Ultra-speed (Ultra) and Ektaspeed (Ekta) films for the detection of caries. A total of 103 occlusal and 224 proximal surfaces were examined independently by three observers. A histologic examination performed after the teeth were sectioned served as the validation method for lesion depth. Receiver operating characteristic curve areas were calculated to express the diagnostic accuracy. In the occlusal surfaces the receiver operating characteristic curve areas ranged from 0.764 (in Ultra films) to 0.800 (in Ekta films). In the proximal surfaces the receiver operating characteristic curve areas ranged from 0.550 (in Ultra films) to 0.696 (in Plus films). No statistically significant differences were found between the different film types. PMID:8665322

  16. Rapid genome detection of Schmallenberg virus and bovine viral diarrhea virus by use of isothermal amplification methods and high-speed real-time reverse transcriptase PCR.

    PubMed

    Aebischer, Andrea; Wernike, Kerstin; Hoffmann, Bernd; Beer, Martin

    2014-06-01

    Over the past few years, there has been an increasing demand for rapid and simple diagnostic tools that can be applied outside centralized laboratories by using transportable devices. In veterinary medicine, such mobile test systems would circumvent barriers associated with the transportation of samples and significantly reduce the time to diagnose important infectious animal diseases. Among a wide range of available technologies, high-speed real-time reverse transcriptase quantitative PCR (RT-qPCR) and the two isothermal amplification techniques loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA) represent three promising candidates for integration into mobile pen-side tests. The aim of this study was to investigate the performance of these amplification strategies and to evaluate their suitability for field application. In order to enable a valid comparison, novel pathogen-specific assays have been developed for the detection of Schmallenberg virus and bovine viral diarrhea virus. The newly developed assays were evaluated in comparison with established standard RT-qPCR using samples from experimentally or field-infected animals. Even though all assays allowed detection of the target virus in less than 30 min, major differences were revealed concerning sensitivity, specificity, robustness, testing time, and complexity of assay design. These findings indicated that the success of an assay will depend on the integrated amplification technology. Therefore, the application-specific pros and cons of each method that were identified during this study provide very valuable insights for future development and optimization of pen-side tests. PMID:24648561

  17. An approach to on-line electrospray mass spectrometric detection of polypeptide antibiotics of enramycin for high-speed counter-current chromatographic separation.

    PubMed

    Inoue, Koichi; Hattori, Yasuko; Hino, Tomoaki; Oka, Hisao

    2010-04-01

    In the field of pharmaceutical and biomedical analysis of peptides, a rapid on-line detection and identification for a methodology have been required for the discovery of new biological active products. In this study, a high-speed counter-current chromatography with electrospray mass spectrometry (HSCCC/ESI-MS) was developed for the on-line detection and purification of polypeptide antibiotics of enramycin-A and -B. The analytes were purified on HSCCC model CCC-1000 (multi-layer coil planet centrifuge) with a volatile solvent of two-phase system composed of n-butanol/hexane/0.05% aqueous trifluoroacetic acid solution (43/7/50, V/V/V), and detected on an LCMS-2010EV quadrupole mass spectrometer fitted with an ESI source system in positive ionization following scan mode (m/z 100-2000). The HSCCC/ESI-MS peaks indicated that enramycin-A (major m/z 786 [M+3H](3+) and minor m/z 1179 [M+2H](2+)) and enramycin-B (major m/z 791 [M+3H](3+) and minor m/z 1185 [M+2H](2+)) have the peak resolution value of 2.9 from 15mg of loaded enramycin powder. The HSCCC collected amounts of the peak fractions were additionally 4.3mg (enramycin-A), and 5.9mg (enramycin-B), respectively. These purified substances were analyzed by LC/ESI-MS with scan positive mode. Based on the LC/ESI-MS chromatograms and spectra of the fractions, enramycin-A and -B were estimated to be over 95% purity. The overall results indicate that this approach of HSCCC/ESI-MS is a powerful technique for the purification and identification of bioactive peptides. PMID:20004073

  18. The Evaluation of Effect of Developer Age in the Detection of Approximal Caries Using Three Speed Dental X-Ray Films: An In-Vitro Study

    PubMed Central

    Madalli, Vijaylaxmi B; Annigeri, Rajeshwari G; Basavaraddi, Shrinivas M

    2014-01-01

    compared to Ultraspeed film. With respect to film, all films had equal diagnostic accuracy upto three weeks. From fourth week Ultraspeed and Agfa films were considerably better than E speed film. E speed film was inferior in the depleted solution compared to other two solutions. With respect to lesion detection Agfa film was inferior to other two films. Conclusion: All three films had equal diagnostic accuracy in fresh solution. Considering the significant reduction in patient radiation with Ektaspeed film, this should be the film of choice whenever possible. As far as the diagnosis of approximal caries is concerned processing solutions should not be used longer than 3 weeks. PMID:24783146

  19. Detection of the position, direction and speed of sliding contact with a multi-layer compliant tactile sensor fabricated using direct-print technology

    NASA Astrophysics Data System (ADS)

    Vatani, Morteza; Engeberg, Erik D.; Choi, Jae-Won

    2014-09-01

    A multi-layer resistance based compliant tactile sensor was fabricated using direct-print (DP) and soft molding processes. The sensor consists of two layers of embedded stretchable sensing elements sandwiched by three layers of a polyurethane rubber material. The sensing elements were created by the DP process using a photopolymer filled with multi-wall carbon nanotubes, which exhibit the property of piezoresistivity. The printed sensing elements were fully cured using ultraviolet light. The sensing elements within each layer of the sensor structure change in electrical resistance when external forces are applied. By processing the measured sensor signals, the fabricated sensor was able to detect the position of contact forces with a 3 mm spatial resolution, as well as their two-dimensional translation directions and speeds. Based on the results, it is concluded that the fabricated sensors are promising in robotic applications and the developed process and material can be a reliable and robust way to build highly stretchable tactile sensors.

  20. Cloud shadow speed sensor

    NASA Astrophysics Data System (ADS)

    Fung, V.; Bosch, J. L.; Roberts, S. W.; Kleissl, J.

    2014-06-01

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system is presented that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term solar irradiance forecasts. The cloud shadow speed sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud shadow motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground-measured irradiance (linear cloud edge, LCE), and a UC San Diego sky imager (USI). The CSS detected artificial shadow directions and speeds to within 15° and 6% accuracy, respectively. The CSS detected (real) cloud shadow directions and speeds with average weighted root-mean-square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s-1 when compared to LCE results.

  1. Cloud speed sensor

    NASA Astrophysics Data System (ADS)

    Fung, V.; Bosch, J. L.; Roberts, S. W.; Kleissl, J.

    2013-10-01

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud motion vectors to estimate power plant ramp rates and provide short term solar irradiance forecasts is presented. The Cloud Speed Sensor (CSS) is constructed using an array of luminance sensors and high-speed data acquisition to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground measured irradiance (Linear Cloud Edge, LCE), and a UC San Diego Sky Imager (USI). The CSS detected artificial shadow directions and speeds to within 15 and 6% accuracy, respectively. The CSS detected (real) cloud directions and speeds without average bias and with average weighted root mean square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s-1 when compared to LCE results.

  2. Gated high speed optical detector

    NASA Technical Reports Server (NTRS)

    Green, S. I.; Carson, L. M.; Neal, G. W.

    1973-01-01

    The design, fabrication, and test of two gated, high speed optical detectors for use in high speed digital laser communication links are discussed. The optical detectors used a dynamic crossed field photomultiplier and electronics including dc bias and RF drive circuits, automatic remote synchronization circuits, automatic gain control circuits, and threshold detection circuits. The equipment is used to detect binary encoded signals from a mode locked neodynium laser.

  3. Quantitative Upright–Supine High-Speed SPECT Myocardial Perfusion Imaging for Detection of Coronary Artery Disease: Correlation with Invasive Coronary Angiography

    PubMed Central

    Nakazato, Ryo; Tamarappoo, Balaji K.; Kang, Xingping; Wolak, Arik; Kite, Faith; Hayes, Sean W.; Thomson, Louise E.J.; Friedman, John D.; Berman, Daniel S.; Slomka, Piotr J.

    2011-01-01

    A recently developed camera system for high-speed SPECT (HS-SPECT) myocardial perfusion imaging shows excellent correlation with conventional SPECT. Our goal was to test the diagnostic accuracy of an automated quantification of combined upright and supine myocardial SPECT for detection of coronary artery disease (CAD) (≥70% luminal diameter stenosis or, in left main coronary artery, ≥50% luminal diameter stenosis) in comparison to invasive coronary angiography (ICA). Methods We studied 142 patients undergoing upright and supine HS-SPECT, including 56 consecutive patients (63% men; mean age 6 ± SD, 64 ± 13 y; 45% exercise stress) without known CAD who underwent diagnostic ICA within 6 mo of HS-SPECT and 86 consecutive patients with a low likelihood of CAD. Reference limits for upright and supine HS-SPECT were created from studies of patients with a low likelihood of CAD. Automated software adopted from supine–prone analysis was used to quantify the severity and extent of perfusion abnormality and was expressed as total perfusion deficit (TPD). TPD was obtained for upright (U-TPD), supine (S-TPD), and combined upright–supine acquisitions (C-TPD). Stress U-TPD ≥ 5%, S-TPD ≥ 5%, and C-TPD ≥ 3% myocardium were considered abnormal for per-patient analysis, and U-TPD, S-TPD, and C-TPD ≥ 2% in each coronary artery territory were considered abnormal for per-vessel analysis. Results On a per-patient basis, the sensitivity was 91%, 88%, and 94% for U-TPD, S-TPD, and C-TPD, respectively, and specificity was 59%, 73%, and 86% for U-TPD, S-TPD, and C-TPD, respectively. C-TPD had a larger area under the receiver-operating-characteristic curve than U-TPD or S-TPD for identification of stenosis ≥ 70% (0.94 vs. 0.88 and 0.89, P < 0.05 and not significant, respectively). On a per-vessel basis, the sensitivity was 67%, 66%, and 69% for U-TPD, S-TPD, and C-TPD, respectively, and specificity was 91%, 94%, and 97% for U-TPD, S-TPD, and C-TPD, respectively (P = 0

  4. Speed Calculator

    NASA Technical Reports Server (NTRS)

    Burch, John L.; Billions, James C.

    1976-01-01

    An apparatus for measuring the velocity of a vehicle traveling between first and second measured points. The apparatus includes a cylindrical housing having an open top for receiving a transparent disk. Indicia representing speed calibrations is circumferentially spaced adjacent an outer perimeter of the disk. A stopwatch is carried in the housing below said disk and has a rotatable hand which rotates at a predetermined rate under the indicia. A lamp is carried below the stopwatch for illuminating the indicia carried on the transparent disk. The stopwatch is started when the vehicle passes a first reference point and stopped when the vehicle passes the second reference point. Thus, when the hand is stopped, such points to the calibrated indicia on said disk indicating the velocity of a vehicle.

  5. Fluorescence based explosive detection: from mechanisms to sensory materials.

    PubMed

    Sun, Xiangcheng; Wang, Ying; Lei, Yu

    2015-11-21

    The detection of explosives is one of the current pressing concerns in global security. In the past few decades, a large number of emissive sensing materials have been developed for the detection of explosives in vapor, solution, and solid states through fluorescence methods. In recent years, great efforts have been devoted to develop new fluorescent materials with various sensing mechanisms for detecting explosives in order to achieve super-sensitivity, ultra-selectivity, as well as fast response time. This review article starts with a brief introduction on various sensing mechanisms for fluorescence based explosive detection, and then summarizes in an exhaustive and systematic way the state-of-the-art of fluorescent materials for explosive detection with a focus on the research in the recent 5 years. A wide range of fluorescent materials, such as conjugated polymers, small fluorophores, supramolecular systems, bio-inspired materials and aggregation induced emission-active materials, and their sensing performance and sensing mechanism are the centerpiece of this review. Finally, conclusions and future outlook are presented and discussed. PMID:26335504

  6. The detection of lubricating oil viscosity changes in gearbox transmission systems driven by sensorless variable speed drives using electrical supply parameters

    NASA Astrophysics Data System (ADS)

    Abusaad, S.; Brethee, K.; Assaeh, M.; Zhang, R.; Gu, F.; Ball, A. D.

    2015-07-01

    Lubrication oil plays a decisive role to maintain a reliable and efficient operation of gear transmissions. Many offline methods have been developed to monitor the quality of lubricating oils. This work focus on developing a novel online method to diagnose oil degradation based on the measurements from power supply system to the gearbox. Experimental studies based on an 10kW industrial gearbox fed by a sensorless variable speed drive (VSD) shows that measurable changes in both static power and dynamic behaviour are different with lube oils tested. Therefore, it is feasible to use the static power feature to indicate viscosity changes at low and moderate operating speeds. In the meantime, the dynamic feature can separate viscosity changes for all different tested cases.

  7. Review of high speed communications photomultiplier detectors

    NASA Technical Reports Server (NTRS)

    Enck, R. S.; Abraham, W. G.

    1978-01-01

    Four types of newly developed high speed photomultipliers are discussed: all electrostatic; static crossed field; dynamic crossed field; and hybrid (EBS). Design, construction, and performance parameters of each class are presented along with limitations of each class of device and prognosis for its future in high speed light detection. The particular advantage of these devices lies in high speed applications using low photon flux, large cathode areas, and broadband optical detection.

  8. Zero-dark-counting high-speed X-ray photon detection using a cerium-doped yttrium aluminum perovskite crystal and a small photomultiplier tube and its application to gadolinium imaging

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Satoshi; Sato, Eiichi; Oda, Yasuyuki; Nakamura, Ryuji; Oikawa, Hirobumi; Yabuushi, Tomonori; Ariga, Hisanori; Ehara, Shigeru

    2014-04-01

    X-ray photons are detected using a cerium-doped yttrium aluminum perovskite [YAP(Ce)] single-crystal scintillator with a decay time of 30 ns and a small-sized photomultiplier tube (SPMT). The negative output pulse from the SPMT is amplified by a high-speed inverse amplifier, and the event pulses are sent to a multichannel analyzer to measure X-ray spectra. The energy resolution of the spectrometer was 15% at 59.5 keV. We carried out photon-counting computed tomography using gadolinium media with a maximum rate of 650 kilo counts per second and confirmed the energy-dispersive effect with changes in the description voltage of event pulses using a high-speed comparator.

  9. Rapid detection of foot-and-mouth disease virus, influenza A virus and classical swine fever virus by high-speed real-time RT-PCR.

    PubMed

    Wernike, Kerstin; Beer, Martin; Hoffmann, Bernd

    2013-10-01

    High sensitivity, minor risk of cross-contamination and in particular the rapid reaction time make quantitative real-time polymerase chain reaction (qPCR) assays well suited for outbreak investigations as well as for monitoring epidemics of pathogens. In this study qPCR assays for three highly contagious animal diseases, namely foot-and-mouth-disease (FMD), influenza A (IA) and classical swine fever (CSF) have been developed. Furthermore, an amplification control targeting 18S ribosomal RNA was included. Each assay was validated with samples from infected animals using three different standard qPCR-machines in two thermal profiles: one standard and one high-speed approach, respectively. The high-speed PCR assays allowed the reliable diagnosis of FMD, influenza A and CSF in less than 28 min with an analytical sensitivity of at least 200 genome copies/μl in every case, with slight differences regarding reaction time and sensitivity for the individual PCR-cycler instruments. Therefore, the newly established rapid RT-PCR systems will be a valuable method for the monitoring and control of these three important viruses and will be a robust option for the development of novel molecular pen-side tests. PMID:23702025

  10. A new approach to live reaction monitoring using active flow technology in ultra-high-speed HPLC with mass spectral detection.

    PubMed

    Kocic, Danijela; Andrew Shalliker, R

    2015-12-01

    A new type of chromatography column referred to as a parallel segmented flow (PSF) column enables ultra-high-speed high-performance liquid chromatography-MS to be undertaken. This occurs because the separation efficiency obtained on PSF columns has been shown in prior studies to be superior to conventional columns, and the flow stream is split radially inside the outlet end fitting of the column, rather than in an axial post-column flow stream split. As a result, the flow through the column can be five times higher than the flow through the MS. In this work, the degradation of amino acids in dilute nitric acid was used to illustrate the process. Separations were obtained in less than 12 s, although the reinjection process was initiated 6 s after the previous injection. The degradation rate constant of tryptophan, in the presence of tyrosine and phenylalanine, was determined. PMID:26634974

  11. Automated detection of feeding strikes by larval fish using continuous high-speed digital video: a novel method to extract quantitative data from fast, sparse kinematic events.

    PubMed

    Shamur, Eyal; Zilka, Miri; Hassner, Tal; China, Victor; Liberzon, Alex; Holzman, Roi

    2016-06-01

    Using videography to extract quantitative data on animal movement and kinematics constitutes a major tool in biomechanics and behavioral ecology. Advanced recording technologies now enable acquisition of long video sequences encompassing sparse and unpredictable events. Although such events may be ecologically important, analysis of sparse data can be extremely time-consuming and potentially biased; data quality is often strongly dependent on the training level of the observer and subject to contamination by observer-dependent biases. These constraints often limit our ability to study animal performance and fitness. Using long videos of foraging fish larvae, we provide a framework for the automated detection of prey acquisition strikes, a behavior that is infrequent yet critical for larval survival. We compared the performance of four video descriptors and their combinations against manually identified feeding events. For our data, the best single descriptor provided a classification accuracy of 77-95% and detection accuracy of 88-98%, depending on fish species and size. Using a combination of descriptors improved the accuracy of classification by ∼2%, but did not improve detection accuracy. Our results indicate that the effort required by an expert to manually label videos can be greatly reduced to examining only the potential feeding detections in order to filter false detections. Thus, using automated descriptors reduces the amount of manual work needed to identify events of interest from weeks to hours, enabling the assembly of an unbiased large dataset of ecologically relevant behaviors. PMID:26994179

  12. Development of a fast and convenient method for the isolation of triterpene saponins from Actaea racemosa by high-speed countercurrent chromatography coupled with evaporative light scattering detection.

    PubMed

    Cicek, Serhat Sezai; Schwaiger, Stefan; Ellmerer, Ernst Peter; Stuppner, Hermann

    2010-03-01

    In the present work, a fast and simple method for the separation and purification of triterpene saponins from Actaea racemosa was successfully established. Accelerated solvent extraction was used for defatting and extracting of the subaerial parts, giving a triterpene enriched crude extract. Size exclusion chromatography was used to separate actein and 23-epi-26-deoxyactein from other triterpenoids, which were collected in a third fraction. This most complex third fraction was applied to high-speed countercurrent chromatography, a well-established technique for the separation of saponins. Separation parameters were first optimized on an analytical level, using a hyphenated HSCCC-ELSD setup, before the system was scaled up to preparative size. The resulting two-phase solvent system, consisting of N-hexane-acetone-ethyl acetate-2-propanol-ethanol-water (3.5 : 1 : 2 : 1 : 0.5 : 2, v/v/v/v/v/v), enabled the isolation of 23-O-acetylshengmanol-3-O- beta-D-xylopyranoside (17.4 mg), cimiracemoside D (19.5 mg), 25-O-acetylcimigenol-3-O-beta-D-xylopyranoside (7.1 mg) and the aglycone cimigenol (5.9 mg). Purity of the isolated substances was 96.8 %, 96.2 %, 97.9 %, and 98.4 %, respectively. The same method was suitable for the purification of actein and 23-epi-26-deoxyactein, with purities of 97.0 % and 98.3 %. PMID:19847744

  13. Resonant cavity enhanced InGaAs photodiodes for high speed detection of 1.55 μm infrared radiation

    NASA Astrophysics Data System (ADS)

    Kaniewski, J.; Muszalski, J.; Pawluczyk, J.; Piotrowski, J.

    2005-05-01

    Resonant cavity enhanced photodetectors are promising candidates for applications in high-speed optical communications due to their high quantum efficiency and large bandwidth. This is a consequence of placing the thin absorber of the photodetector inside a Fabry-Perot microcavity so the absorption could be enhanced by recycling the photons with resonance wavelength. The performance of uncooled resonant cavity enhanced InGaAs/InAlAs photovoltaic devices operating near 1.55 μm has been studied both theoretically and experimentally. The analyses include two different types of structures with cavity end mirrors made of semiconducting and metallic reflectors as well as semiconducting and hybrid (dielectric Si3N4/SiO2 + metal) Bragg reflectors. Optimization of the device design includes: absorption layer thickness, position of absorption layer within the cavity and number of layers in distributed Bragg reflectors. Dependence of absorption on wavelength and incidence angle are discussed. Various issues related to applications of resonance cavity enhanced photodiodes in optical systems are considered. Practical devices with metallic and hybrid mirrors were fabricated by molecular beam epitaxy and by microwave-compatible processing. A properly designed device of this type has potential for subpicosecond response time.

  14. Theoretical Research Program on Bio-inspired Inorganic Hydrogen Generating Catalysts and Electrodes

    SciTech Connect

    Selloni, Annabella; Car, Roberto; Cohen, Morrel H.

    2014-04-17

    In this project, we have successfully designed and characterized a promising biomimetic catalyst/electrode complex, [FeFe]P/FeS2 for producing hydrogen from water. It is comprised of earth-abundant materials and, with a diffusion-limited rate in acidified water, is efficient as well as oxygen tolerant. The theoretical techniques we have developed and the experience we have gained are broadly applicable for the design and analysis of biomimetic electrochemically active catalysts.

  15. Controlling protein translocation through nanopores with bio-inspired fluid walls

    NASA Astrophysics Data System (ADS)

    Yusko, Erik C.; Johnson, Jay M.; Majd, Sheereen; Prangkio, Panchika; Rollings, Ryan C.; Li, Jiali; Yang, Jerry; Mayer, Michael

    2011-04-01

    Synthetic nanopores have been used to study individual biomolecules in high throughput, but their performance as sensors does not match that of biological ion channels. Challenges include control of nanopore diameters and surface chemistry, modification of the translocation times of single-molecule analytes through nanopores, and prevention of non-specific interactions with pore walls. Here, inspired by the olfactory sensilla of insect antennae, we show that coating nanopores with a fluid lipid bilayer tailors their surface chemistry and allows fine-tuning and dynamic variation of pore diameters in subnanometre increments. Incorporation of mobile ligands in the lipid bilayer conferred specificity and slowed the translocation of targeted proteins sufficiently to time-resolve translocation events of individual proteins. Lipid coatings also prevented pores from clogging, eliminated non-specific binding and enabled the translocation of amyloid-beta (Aβ) oligomers and fibrils. Through combined analysis of their translocation time, volume, charge, shape and ligand affinity, different proteins were identified.

  16. Synthesis and Reactivity of a Bio-inspired Dithiolene Ligand and its Mo Oxo Complex.

    PubMed

    Porcher, Jean-Philippe; Fogeron, Thibault; Gomez-Mingot, Maria; Chamoreau, Lise-Marie; Li, Yun; Fontecave, Marc

    2016-03-18

    An original synthesis of the fused pyranoquinoxaline dithiolene ligand qpdt(2-) is discussed in detail. The most intriguing step is the introduction of the dithiolene moiety by Pd-catalyzed carbon-sulfur coupling. The corresponding Mo(IV) O complex (Bu4 N)2 [MoO(qpdt)2 ] (2) underwent reversible protonation in a strongly acidic medium and remained stable under anaerobic conditions. Besides, 2 was found to be very sensitive towards oxygen, as upon oxidation it formed a planar dithiin derivative. Moreover, the qpdt(2-) ligand in the presence of [MoCl4 (tBuNC)2 ] formed a tetracyclic structure. The products resulting from the unique reactivity of qpdt(2-) were characterized by X-ray diffraction, mass spectrometry, NMR spectroscopy, UV/Vis spectroscopy, and electrochemistry. Plausible mechanisms for the formation of these products are also proposed. PMID:26880579

  17. Bio-Inspired Computing, Information Swarms, and the Problem of Data Fusion

    NASA Astrophysics Data System (ADS)

    Nordmann, Brian

    The problem of information overload becomes a huge challenge, particularly when attempting to understanding how to introduce more and more disparate data streams into a data system. Little has been done on how to make those data streams understandable and usable by an analyst. A new paradigm is constructed here, unconstrained by the limits of the current desktop computer, to develop new ways of processing and analyzing data based on the behavior of cellular scale organisms. The additional issue of analytic "groupthink" or "information swarms" is also addressed, with potential solutions to the problem of "paralysis by analysis."

  18. Bio-inspired Polymer Composite Actuator and Generator Driven by Water Gradients

    PubMed Central

    Ma, Mingming; Guo, Liang; Anderson, Daniel G.; Langer, Robert

    2013-01-01

    Here we describe the development of a water-responsive polymer film; combining both a rigid matrix (polypyrrole) and a dynamic network (polyol-borate), strong and flexible polymer films were developed that can exchange water with the environment to induce film expansion and contraction, resulting in rapid and continuous locomotion. The film actuator can generate contractile stress up to 27 MPa, lift objects 380 times heavier than itself, and transport cargo 10 times heavier than itself. We have assembled a generator by associating this actuator with a piezoelectric element. Driven by water gradients, this generator outputs alternating electricity at ∼0.3 Hz, with a peak voltage of ∼1.0 V. The electrical energy is stored in capacitors that could power micro- and nano-electronic devices. PMID:23307738

  19. Vinyl Dimethyl Azlactone-Containing Copolymers: Towards Bio-Inspired Surfaces/Polymer-Protein Conjugates

    SciTech Connect

    Messman, Jamie M; Banaszak, Abigail; Barrninger, Joshua; Mays, Jimmy; Kilbey, II, S Michael

    2007-01-01

    Stimuli-responsive, vinyl dimethyl azlactone/vinyl pyrrolidone (VDMA/VP) copolymers have been prepared using free radical polymerization techniques. These copolymers are subsequently the basis for the design of polymer brushes where the system is composed of a polystyrene (PS) block and a VDMA/VP copolymer block. Copolymers have been prepared using reversible addition fragmentation chain transfer (RAFT) polymerization technique. Using a solvent that is selective for the VDMA/VP block, these PS-block-P[VDMA/VP] copolymers can be preferentially adsorbed at the solid-fluid interface through the PS block to form a polymer "brush". Because VDMA is known to quantitatively react with amines, exposure of the copolymer to a solution containing amino acids (e.g. glycine) yields a bio-functionalized polymer brush. In this paper we will report on the synthesis and characterization of VDMA/VP copolymers including compositional analysis using FTIR and NMR spectroscopies.

  20. Mechanics ofadhesion and contact self-cleaning of bio-inspired microfiberadhesives

    NASA Astrophysics Data System (ADS)

    Abusomwan, Uyiosa Anthony

    The remarkable attachment system of geckos has inspired the development of dry microfiber adhesives through the last two decades. Some of the notable characteristics of gecko-inspired fibrillar adhesives include: strong, directional, and controllable adhesion to smooth and rough surfaces in air, vacuum, and under water; ability to maintain strong adhesion during repeated use; anti-fouling and self-cleaning after contamination. Given these outstanding qualities, fibrillar adhesives promise an extensive range of use in industrial, robotic, manufacturing, medical, and consumer products. Significant advancements have been made in the design of geckoinspired microfiber adhesives with the characteristic properties listed above, with the exception of the anti-fouling and self-cleaning features. The self-cleaning mechanism of the gecko's adhesion system plays an important role to its ability to remain sticky in various environments. Similarly, enabling self-cleaning capability for synthetic microfiber adhesives will lead to robust performance in various areas of application. Presently, the practical use of fibrillar adhesives is restricted mainly to clean environments, where they are free from contaminants. The goal of this thesis is to conduct a detailed study of the mechanisms and mechanics of contact-based self-cleaning of gecko-inspired microfiber adhesives. This work focuses on contact self-cleaning mechanisms, as a more practical approach to cleaning. Previous studies on the cleaning of microfiber adhesives have mostly focused on mechanisms that involve complete removal of the contaminants from the adhesive. In this thesis, a second cleaning process is proposed whereby particles are removed from the tip of the microfibers and embedded between adjacent microfibers or in grooves patterned onto the adhesive, where they are no longer detrimental to the performance of the adhesive. In this work, a model of adhesion for microfiber adhesives that take the deformation of the backing layer under individual microfiber is developed. The dependence of adhesion of microfiber adhesives on the rate of unloading is also modeled and verified using experiments. The models of adhesion presented are later used to study the mechanics of contact self-cleaning of microfiber adhesives. Three major categories of self-cleaning are identified as wet self-cleaning, dynamic self-cleaning, and contact self-cleaning. A total of seven self-cleaning mechanisms that are associated with these categories are also presented and discussed. Results from the self-cleaning model and experiments show that shear loading plays an important role in self-cleaning. The underlying mechanism of contact self-cleaning due to normal and shear loading for spherical contaminants is found to be the particle rolling between the adhesive and a contacted substrate. Results from the model and experiments also show that small microfiber tips (much less than the size of the contaminants) are favorable for self-cleaning. On the other hand, large microfiber tips (much larger than the size of the contaminants) are favorable for anti-fouling of the microfiber adhesive. Results from this work suggests that the sub-micrometer size of the gecko's adhesive fibers and the lamellae under the gecko toes contribute to its outstanding self-cleaning performance. The results presented in this thesis can be implemented in the design of microfiber adhesives with robust adhesion, self-cleaning and anti-fouling characteristic, for use in numerous applications and in various environments.

  1. Prediction of the adhesive behavior of bio-inspired functionally graded materials against rough surfaces

    NASA Astrophysics Data System (ADS)

    Peijian, Chen; Juan, Peng; Yucheng, Zhao; Feng, Gao

    2014-06-01

    Roughness effect and adhesion properties are important characteristics to be accessed in the development of functionally graded materials for biological and biomimetic applications, particularly for the hierarchical composition in biomimetic gecko robot. A multi-asperities adhesion model to predict the adhesive forces is presented in this work. The effect of surface roughness and graded material properties, which significantly alter the adhesive strength between contact bodies, can be simultaneously considered in the generalized model. It is found that proper interfacial strength can be controlled by adjusting surface roughness σ / R, graded exponent k and material parameter E*R / Δγ. The results should be helpful in the design of new biomimetic materials and useful in application of micro functional instruments.

  2. Superhydrophobic gecko feet with high adhesive forces towards water and their bio-inspired materials

    NASA Astrophysics Data System (ADS)

    Liu, Kesong; Du, Jiexing; Wu, Juntao; Jiang, Lei

    2012-01-01

    Functional integration is an inherent characteristic for multiscale structures of biological materials. In this contribution, we first investigate the liquid-solid adhesive forces between water droplets and superhydrophobic gecko feet using a high-sensitivity micro-electromechanical balance system. It was found, in addition to the well-known solid-solid adhesion, the gecko foot, with a multiscale structure, possesses both superhydrophobic functionality and a high adhesive force towards water. The origin of the high adhesive forces of gecko feet to water could be attributed to the high density nanopillars that contact the water. Inspired by this, polyimide films with gecko-like multiscale structures were constructed by using anodic aluminum oxide templates, exhibiting superhydrophobicity and a strong adhesive force towards water. The static water contact angle is larger than 150° and the adhesive force to water is about 66 μN. The resultant gecko-inspired polyimide film can be used as a ``mechanical hand'' to snatch micro-liter liquids. We expect this work will provide the inspiration to reveal the mechanism of the high-adhesive superhydrophobic of geckos and extend the practical applications of polyimide materials.

  3. Spectral Transition in Bio-Inspired Self-Assembled Peptide Nucleic Acid Photonic Crystals.

    PubMed

    Berger, Or; Yoskovitz, Eyal; Adler-Abramovich, Lihi; Gazit, Ehud

    2016-03-01

    The self-assembly of guanine-based peptide nucleic acid monomers into photonic crystals is described. A highly reflective lattice of guanine nanocrystals is found in the skin and ocular tissues of different species providing vivid structural colors. The fabricated guanine-based supramolecular structures respond to changes in osmolarity similar to the active spectral change mechanism employed by chameleons. PMID:26779770

  4. Designing a bio-inspired self-propelling hydrogel micro-swimmer

    NASA Astrophysics Data System (ADS)

    Nikolov, Svetoslav; Yeh, Peter; Alexeev, Alexander

    2014-11-01

    Artificial micro-swimmers have found numerous applications in microfluidics, drug delivery systems, and nanotechnology. In our current research we use dissipative particle dynamics to design and optimize a self-propelling hydrogel micro-swimmer with an X-shaped flat geometry and bi-layered hydrogel structure. The two polymeric layers that bind to each other have identical material properties but distinctive chemical responses to external stimuli. In the presence of outside stimuli one of the layers swells where the other remains passive resulting in hydrogel bending. Our simulations demonstrate that under periodic applications of an external stimulus this actuation routine is capable of creating time-irreversible motion in a low Reynolds number environment. Initially, when the external stimulus is introduced a forward stroke is initiated, as the swimmer first expands and then bends. When the outside stimulus is removed the forward stroke is terminated and a backward stroke begins, as the swimmer contracts and then straightens. Propulsion results due to the difference in momentum exchange between the forward and backward strokes. We use our simulations to probe how alterations in the material properties of the bi-layered hydrogel can affect swimming performance. Support from NSF CAREER Award (DMR-1255288) is gratefully acknowledged.

  5. Bio-inspired fabrication of stimuli-responsive photonic crystals with hierarchical structures and their applications

    NASA Astrophysics Data System (ADS)

    Lu, Tao; Peng, Wenhong; Zhu, Shenmin; Zhang, Di

    2016-03-01

    When the constitutive materials of photonic crystals (PCs) are stimuli-responsive, the resultant PCs exhibit optical properties that can be tuned by the stimuli. This can be exploited for promising applications in colour displays, biological and chemical sensors, inks and paints, and many optically active components. However, the preparation of the required photonic structures is the first issue to be solved. In the past two decades, approaches such as microfabrication and self-assembly have been developed to incorporate stimuli-responsive materials into existing periodic structures for the fabrication of PCs, either as the initial building blocks or as the surrounding matrix. Generally, the materials that respond to thermal, pH, chemical, optical, electrical, or magnetic stimuli are either soft or aggregate, which is why the manufacture of three-dimensional hierarchical photonic structures with responsive properties is a great challenge. Recently, inspired by biological PCs in nature which exhibit both flexible and responsive properties, researchers have developed various methods to synthesize metals and metal oxides with hierarchical structures by using a biological PC as the template. This review will focus on the recent developments in this field. In particular, PCs with biological hierarchical structures that can be tuned by external stimuli have recently been successfully fabricated. These findings offer innovative insights into the design of responsive PCs and should be of great importance for future applications of these materials.

  6. Bio-inspired, Moisture-Powered Hybrid Carbon Nanotube Yarn Muscles

    PubMed Central

    Kim, Shi Hyeong; Kwon, Cheong Hoon; Park, Karam; Mun, Tae Jin; Lepró, Xavier; Baughman, Ray H.; Spinks, Geoffrey M.; Kim, Seon Jeong

    2016-01-01

    Hygromorph artificial muscles are attractive as self-powered actuators driven by moisture from the ambient environment. Previously reported hygromorph muscles have been largely limited to bending or torsional motions or as tensile actuators with low work and energy densities. Herein, we developed a hybrid yarn artificial muscle with a unique coiled and wrinkled structure, which can be actuated by either changing relative humidity or contact with water. The muscle provides a large tensile stroke (up to 78%) and a high maximum gravimetric work capacity during contraction (2.17 kJ kg−1), which is over 50 times that of the same weight human muscle and 5.5 times higher than for the same weight spider silk, which is the previous record holder for a moisture driven muscle. We demonstrate an automatic ventilation system that is operated by the tensile actuation of the hybrid muscles caused by dew condensing on the hybrid yarn. This self-powered humidity-controlled ventilation system could be adapted to automatically control the desired relative humidity of an enclosed space. PMID:26973137

  7. Bio-inspired design of geometrically interlocked 3D printed joints

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Oliva, Noel; Kumar's Lab Team

    The morphology of the adhesive-adherend interface significantly affects the mechanical behavior of adhesive joints. As seen in some biocomposites like human skull, or the nacre of some bivalve molluscs' shells, a geometrically interlocking architecture of interfaces creates toughening and strengthening mechanisms enhancing the mechanical properties of the joint. In an attempt to characterize this mechanical interlocking mechanism, this study is focused on computational and experimental investigation of a single-lap joint with a very simple geometrically interlocked interface design in which both adherends have a square waveform configuration of the joining surfaces. This square waveform configuration contains a positive and a negative rectangular teeth per cycle in such a way that the joint is symmetric about the mid-bondlength. Both physical tests performed on 3D printed prototypes of joints and computational results indicate that the joints with square waveform design have higher strength and damage tolerance than those of joints with flat interface. In order to identify an optimal design configuration of this interface, a systematic parametric study is conducted by varying the geometric and material properties of the non-flat interface. This work was supported by Lockheed Martin (Award No: 12NZZ1).

  8. VLSI Implementation of a Bio-inspired Olfactory Spiking Neural Network

    NASA Astrophysics Data System (ADS)

    Hsieh, Hung-Yi; Tang, Kea-Tiong

    2011-11-01

    This paper proposes a VLSI circuit implementing a low power, high-resolution spiking neural network (SNN) with STDP synapses, inspired by mammalian olfactory systems. By representing mitral cell action potential by a step function, the power consumption and the chip area can be reduced. By cooperating sub-threshold oscillation and inhibition, the network outputs can be distinct. This circuit was fabricated using the TSMC 0.18 μm 1P6M CMOS process. Post-layout simulation results are reported.

  9. Bio-inspired photo-electronic material based on photosynthetic proteins

    NASA Astrophysics Data System (ADS)

    Lebedev, Nikolai; Trammell, Scott A.; Tsoi, Stanislav; Spano, Anthony; Kim, Jin Ho; Xu, Jimmy; Twigg, Mark E.; Schnur, Joel M.

    2009-08-01

    The construction of efficient light energy converting (photovoltaic and photo-electronic) devices is a current and great challenge in science and technology and one that will have important economic consequences. Several innovative nanoelectronic materials were proposed to achieve this goal, semiconductor quantum dots, metallic nanowires and carbon nanotubes (CNT) are among them. As a charge separating unit for light energy conversion, we propose the utilization of the most advanced photoelectronic material developed by nature, photosynthetic reaction center proteins. As a first step in this direction, we constructed a novel bioinorganic nanophotoelectronic material with photoactive photosynthetic reaction center (RC) proteins encapsulated inside a multiwall CNT arrayed electrode. The material consists of photosynthetic RC-cytochrome complexes acting as charge separating units bound to the inner walls of a CNT electrode and ubiquinone-10 (Q2) serving as a soluble electron-transfer mediator to the counter electrode. The proteins were immobilized inside carbon nanotubes by a Ni(NTA)-alkane-pyrene linker, forming a self-assembled monolayer (SAM) on the surface of inner CNT walls and allowing for unidirectional protein orientation. The material demonstrates an enhanced photoinduced electron transfer rate and shows substantial improvement in photocurrent density compared to that obtained with the same proteins when immobilized on planar graphite (HOPG) electrode. The results suggest that protein encapsulation in precisely organized arrayed tubular electrode architecture can considerably improve the performance of photovoltaic, photoelectronic, or biofuel cell devices. They demonstrate the potential for substantial advantages of precisely organized nano electrode tubular arrayed architecture for variety biotechnological applications.

  10. Building bio-inspired artificial functional nanochannels: from symmetric to asymmetric modification.

    PubMed

    Hou, Xu; Zhang, Huacheng; Jiang, Lei

    2012-05-29

    Over millions of years, complex processes of intelligent control have evolved in nature. Learning from nature is a continuing theme in the development of smart materials and intelligent systems. For example, biological nanochannels, which are typically ion channels, play a very important role in basic biochemical processes in cells. Inspired by ion channels, in which the components are asymmetrically distributed between the membrane surfaces, the generation of biomimetic smart nanochannels is a broad and varied scientific research field. The design and development of new biomimetic channels includes the use of different shapes of channels, different stimuli-responsive molecules, and different symmetric/asymmetric modification methods. In this Minireview, we summarize recent developments in building functional nanochannels by applying various symmetric and asymmetric modifications. PMID:22505178

  11. Bio-Inspired Mechanotactic Hybrids for Orchestrating Traction-Mediated Epithelial Migration.

    PubMed

    Cai, Pingqiang; Layani, Michael; Leow, Wan Ru; Amini, Shahrouz; Liu, Zhiyuan; Qi, Dianpeng; Hu, Benhui; Wu, Yun-Long; Miserez, Ali; Magdassi, Shlomo; Chen, Xiaodong

    2016-04-01

    A platform of mechanotactic hybrids is established by projecting lateral gradients of apparent interfacial stiffness onto the planar surface of a compliant hydrogel layer using an underlying rigid substrate with microstructures inherited from 3D printed molds. Using this platform, the mechanistic coupling of epithelial migration with the stiffness of the extracellular matrix (ECM) is found to be independent of the interfacial compositional and topographical cues. PMID:26913959

  12. Investigation of Bio-Inspired High Lift Devices for Stall Mitigation

    NASA Astrophysics Data System (ADS)

    Hufstedler, Esteban; McKeon, Beverley J.

    2014-11-01

    A passive upper-surface flap has been shown to increase the lift on a wing after stall and reduce the severity of stall at a wide range of Reynolds numbers. Experiments at Re = 20,000 have been conducted that examined the forces and flow fields around an airfoil with passively moving and static upper-surface flaps. Force measurements confirm the reported post-stall lift-enhancing effect. Particle image velocimetry measurements display the interaction of a significant region of reversed flow with the flap in the lift-enhancing regime. Application of proper orthogonal decomposition techniques to the velocity field data leads to identification of relevant timescales in the separated region and a quantification of the intermittency of vortex shedding that occurs after stall. The support of Airbus for this work is gratefully acknowledged.

  13. From network-to-antibody robustness in a bio-inspired immune system.

    PubMed

    Fernandez-Leon, Jose A; Acosta, Gerardo G; Mayosky, Miguel A

    2011-01-01

    Behavioural robustness at antibody and immune network level is discussed. The robustness of the immune response that drives an autonomous mobile robot is examined with two computational experiments in the autonomous mobile robots trajectory generation context in unknown environments. The immune response is met based on the immune network metaphor for different low-level behaviours coordination. These behaviours are activated when a robot sense the appropriate conditions in the environment in relation to the network current state. Results are obtained over a case study in computer simulation as well as in laboratory experiments with a Khepera II microrobot. In this work, we develop a set of tests where such an immune response is externally perturbed at network or low-level behavioural modules to analyse the robust capacity of the system to unexpected perturbations. Emergence of robust behaviour and high-level immune response relates to the coupling between behavioural modules that are selectively engaged with the environment based on immune response. Experimental evidence leads discussions on a dynamical systems perspective of behavioural robustness in artificial immune systems that goes beyond the isolated immune network response. PMID:21315135

  14. Bio-inspired immobilization of metal oxides on monolithic microreactor for continuous Knoevenagel reaction.

    PubMed

    Song, Wentong; Shi, Da; Tao, Shengyang; Li, Zhaoliang; Wang, Yuchao; Yu, Yongxian; Qiu, Jieshan; Ji, Min; Wang, Xinkui

    2016-11-01

    A facile method is reported to construct monolithic microreactor with high catalytic performance for Knoevenagel reaction. The microreactor is based on hierarchically porous silica (HPS) which has interconnected macro- and mesopores. Then the HPS is surface modified by pyrogallol (PG) polymer. Al(NO3)3 and Mg(NO3)2 are loaded on the surface of HPS through coordination with -OH groups of PG. After thermal treatment, Al(NO3)3 and Mg(NO3)2 are converted Al2O3 and MgO. The as-synthesized catalytic microreactor shows a high and stable performance in Knoevenagel reaction. The microreactor possess large surface area and interconnected pore structures which are beneficial for reactions. Moreover, this economic, facile and eco-friendly surface modification method can be used in loading more metal oxides for more reactions. PMID:27459172

  15. GeoTrack: bio-inspired global video tracking by networks of unmanned aircraft systems

    NASA Astrophysics Data System (ADS)

    Barooah, Prabir; Collins, Gaemus E.; Hespanha, João P.

    2009-05-01

    Research from the Institute for Collaborative Biotechnologies (ICB) at the University of California at Santa Barbara (UCSB) has identified swarming algorithms used by flocks of birds and schools of fish that enable these animals to move in tight formation and cooperatively track prey with minimal estimation errors, while relying solely on local communication between the animals. This paper describes ongoing work by UCSB, the University of Florida (UF), and the Toyon Research Corporation on the utilization of these algorithms to dramatically improve the capabilities of small unmanned aircraft systems (UAS) to cooperatively locate and track ground targets. Our goal is to construct an electronic system, called GeoTrack, through which a network of hand-launched UAS use dedicated on-board processors to perform multi-sensor data fusion. The nominal sensors employed by the system will EO/IR video cameras on the UAS. When GMTI or other wide-area sensors are available, as in a layered sensing architecture, data from the standoff sensors will also be fused into the GeoTrack system. The output of the system will be position and orientation information on stationary or mobile targets in a global geo-stationary coordinate system. The design of the GeoTrack system requires significant advances beyond the current state-of-the-art in distributed control for a swarm of UAS to accomplish autonomous coordinated tracking; target geo-location using distributed sensor fusion by a network of UAS, communicating over an unreliable channel; and unsupervised real-time image-plane video tracking in low-powered computing platforms.

  16. Enhanced Mechanical Performance of Bio-Inspired Hybrid Structures Utilising Topological Interlocking Geometry

    NASA Astrophysics Data System (ADS)

    Djumas, Lee; Molotnikov, Andrey; Simon, George P.; Estrin, Yuri

    2016-05-01

    Structural composites inspired by nacre have emerged as prime exemplars for guiding materials design of fracture-resistant, rigid hybrid materials. The intricate microstructure of nacre, which combines a hard majority phase with a small fraction of a soft phase, achieves superior mechanical properties compared to its constituents and has generated much interest. However, replicating the hierarchical microstructure of nacre is very challenging, not to mention improving it. In this article, we propose to alter the geometry of the hard building blocks by introducing the concept of topological interlocking. This design principle has previously been shown to provide an inherently brittle material with a remarkable flexural compliance. We now demonstrate that by combining the basic architecture of nacre with topological interlocking of discrete hard building blocks, hybrid materials of a new type can be produced. By adding a soft phase at the interfaces between topologically interlocked blocks in a single-build additive manufacturing process, further improvement of mechanical properties is achieved. The design of these fabricated hybrid structures has been guided by computational work elucidating the effect of various geometries. To our knowledge, this is the first reported study that combines the advantages of nacre-inspired structures with the benefits of topological interlocking.

  17. Bio-inspired piezoelectric artificial hair cell sensor fabricated by powder injection molding

    NASA Astrophysics Data System (ADS)

    Han, Jun Sae; Oh, Keun Ha; Moon, Won Kyu; Kim, Kyungseop; Joh, Cheeyoung; Seo, Hee Seon; Bollina, Ravi; Park, Seong Jin

    2015-12-01

    A piezoelectric artificial hair cell sensor was fabricated by the powder injection molding process in order to make an acoustic vector hydrophone. The entire process of powder injection molding was developed and optimized for PMN-PZT ceramic powder. The artificial hair cell sensor, which consists of high aspect ratio hair cell and three rectangular mechanoreceptors, was precisely fabricated through the developed powder injection molding process. The density and the dielectric property of the fabricated sensor shows 98% of the theoretical density and 85% of reference dielectric property of PMN-PZT ceramic powder. With regard to homogeneity, three rectangular mechanoreceptors have the same dimensions, with 3 μm of tolerance with 8% of deviation of dielectric property. Packaged vector hydrophones measure the underwater acoustic signals from 500 to 800 Hz with -212 dB of sensitivity. Directivity of vector hydrophone was acquired at 600 Hz as analyzing phase differences of electric signals.

  18. Bio-inspired CO2 conversion by iron sulfide catalysts under sustainable conditions.

    PubMed

    Roldan, A; Hollingsworth, N; Roffey, A; Islam, H-U; Goodall, J B M; Catlow, C R A; Darr, J A; Bras, W; Sankar, G; Holt, K B; Hogarth, G; de Leeuw, N H

    2015-05-01

    The mineral greigite presents similar surface structures to the active sites found in many modern-day enzymes. We show that particles of greigite can reduce CO2 under ambient conditions into chemicals such as methanol, formic, acetic and pyruvic acid. Our results also lend support to the Origin of Life theory on alkaline hydrothermal vents. PMID:25835242

  19. Bio-inspired Structural Colors from Deposition of Synthetic Melanin Nanoparticles by Evaporative Self-assembly

    NASA Astrophysics Data System (ADS)

    Xiao, Ming; Li, Yiwen; Deheyn, Dimitri; Yue, Xiujun; Gianneschi, Nathan; Shawkey, Matthew; Dhinojwala, Ali

    2015-03-01

    Melanin, a ubiquitous black or brown pigment in the animal kingdom, is a unique but poorly understood biomaterial. Many bird feathers contain melanosomes (melanin-containing organelles), which pack into ordered nanostructures, like multilayer or two-dimensional photonic crystal structures, to produce structural colors. To understand the optical properties of melanin and how melanosomes assemble into certain structures to produce colors, we prepared synthetic melanin (polydopamine) particles with variable sizes and aspect ratios. We have characterized the absorption and refractive index of the synthetic melanin particles. We have also shown that we can use an evaporative process to self-assemble melanin films with a wide range of colors. The colors obtained using this technique is modeled using a thin-film interference model and the optical properties of the synthetic melanin nanoparticles. Our results on self-assembly of synthetic melanin nanoparticles provide an explanation as why the use of melanosomes to produce colors is prevalent in the animal kingdom. National science foundation, air force office of scientific research, human frontier science program.

  20. Bio-inspired synthesis of hybrid silica nanoparticles templated from elastin-like polypeptide micelles

    NASA Astrophysics Data System (ADS)

    Han, Wei; MacEwan, Sarah R.; Chilkoti, Ashutosh; López, Gabriel P.

    2015-07-01

    The programmed self-assembly of block copolymers into higher order nanoscale structures offers many attractive attributes for the development of new nanomaterials for numerous applications including drug delivery and biosensing. The incorporation of biomimetic silaffin peptides in these block copolymers enables the formation of hybrid organic-inorganic materials, which can potentially enhance the utility and stability of self-assembled nanostructures. We demonstrate the design, synthesis and characterization of amphiphilic elastin-like polypeptide (ELP) diblock copolymers that undergo temperature-triggered self-assembly into well-defined spherical micelles. Genetically encoded incorporation of the silaffin R5 peptide at the hydrophilic terminus of the diblock ELP leads to presentation of the silaffin R5 peptide on the coronae of the micelles, which results in localized condensation of silica and the formation of near-monodisperse, discrete, sub-100 nm diameter hybrid ELP-silica particles. This synthesis method, can be carried out under mild reaction conditions suitable for bioactive materials, and will serve as the basis for the development and application of functional nanomaterials. Beyond silicification, the general strategies described herein may also be adapted for the synthesis of other biohybrid nanomaterials as well.The programmed self-assembly of block copolymers into higher order nanoscale structures offers many attractive attributes for the development of new nanomaterials for numerous applications including drug delivery and biosensing. The incorporation of biomimetic silaffin peptides in these block copolymers enables the formation of hybrid organic-inorganic materials, which can potentially enhance the utility and stability of self-assembled nanostructures. We demonstrate the design, synthesis and characterization of amphiphilic elastin-like polypeptide (ELP) diblock copolymers that undergo temperature-triggered self-assembly into well-defined spherical micelles. Genetically encoded incorporation of the silaffin R5 peptide at the hydrophilic terminus of the diblock ELP leads to presentation of the silaffin R5 peptide on the coronae of the micelles, which results in localized condensation of silica and the formation of near-monodisperse, discrete, sub-100 nm diameter hybrid ELP-silica particles. This synthesis method, can be carried out under mild reaction conditions suitable for bioactive materials, and will serve as the basis for the development and application of functional nanomaterials. Beyond silicification, the general strategies described herein may also be adapted for the synthesis of other biohybrid nanomaterials as well. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01407g

  1. Enhanced Mechanical Performance of Bio-Inspired Hybrid Structures Utilising Topological Interlocking Geometry

    PubMed Central

    Djumas, Lee; Molotnikov, Andrey; Simon, George P.; Estrin, Yuri

    2016-01-01

    Structural composites inspired by nacre have emerged as prime exemplars for guiding materials design of fracture-resistant, rigid hybrid materials. The intricate microstructure of nacre, which combines a hard majority phase with a small fraction of a soft phase, achieves superior mechanical properties compared to its constituents and has generated much interest. However, replicating the hierarchical microstructure of nacre is very challenging, not to mention improving it. In this article, we propose to alter the geometry of the hard building blocks by introducing the concept of topological interlocking. This design principle has previously been shown to provide an inherently brittle material with a remarkable flexural compliance. We now demonstrate that by combining the basic architecture of nacre with topological interlocking of discrete hard building blocks, hybrid materials of a new type can be produced. By adding a soft phase at the interfaces between topologically interlocked blocks in a single-build additive manufacturing process, further improvement of mechanical properties is achieved. The design of these fabricated hybrid structures has been guided by computational work elucidating the effect of various geometries. To our knowledge, this is the first reported study that combines the advantages of nacre-inspired structures with the benefits of topological interlocking. PMID:27216277

  2. Bio-Inspired In-Air Sonar Localization: What Artificial Pinnae do for Robotic Bats

    NASA Astrophysics Data System (ADS)

    Schillebeeckx, Filips

    This dissertation investigates the hypothesis that binaural spectral cues, as generated by biomimetic microphone-baffle shapes in a suitable configuration, are both a sufficient and efficient means to realize real-time 3D localization capabilities for an in-air sonar system. We demonstrate 3D localization of real reflectors under realistic noise conditions, a task previously not performed successfully with a single binaural sonar measurement. The principal driving force behind this new approach is the use of two complex artificial pinna structures acting as complex direction-dependent spectral filters on the returning echoes. The technique makes use of broadband spectral cues in the received echoes only. Experiments with complex reflectors illustrate that the active head-related transfer function dominates the echo spectrum, allowing 3D localization in the presence of spectrum distortions caused by unknown reflector filtering. Also, experimental results in which multiple targets are localized simultaneously are presented. It is then investigated how binaural sonar system configuration choices affect 3D spectrum-based reflector localization. The proposed model demonstrates the limits of the spectral cue information provided by conventional transducers. Configurations composed of conventional receivers are evaluated as a function of unknown reflection strength and compared with a system with artificial pinnae receivers. Localization performance is quantified by an information theoretic performance criterion expressing the mutual information carried by a binaural spectrum on the corresponding 3D reflector location. Optimal configurations with conventional transducers are shown to be a function of echo reflection strength and the specific region of interest. The more complex spatial sensitivity patterns of organic pinna forms such as that of the Phyllostomus discolor bat species provide additional spectral cues that greatly improve localization information transfer compared to conventional transducers. Results indicate that the varying acoustic axis in the head-related transfer function of the pinna and even more so the higher peripheral sensitivity around the varying acoustic axis are the driving forces behind the artificial pinna's superior localization performance. Finally, it is shown that technical antennas that do not reproduce all the structural details seen in natural biosonar antennas can be suitable and robust design alternatives for in-air sonar systems intended for use on autonomous robots.

  3. Superhydrophobic gecko feet with high adhesive forces towards water and their bio-inspired materials.

    PubMed

    Liu, Kesong; Du, Jiexing; Wu, Juntao; Jiang, Lei

    2012-02-01

    Functional integration is an inherent characteristic for multiscale structures of biological materials. In this contribution, we first investigate the liquid-solid adhesive forces between water droplets and superhydrophobic gecko feet using a high-sensitivity micro-electromechanical balance system. It was found, in addition to the well-known solid-solid adhesion, the gecko foot, with a multiscale structure, possesses both superhydrophobic functionality and a high adhesive force towards water. The origin of the high adhesive forces of gecko feet to water could be attributed to the high density nanopillars that contact the water. Inspired by this, polyimide films with gecko-like multiscale structures were constructed by using anodic aluminum oxide templates, exhibiting superhydrophobicity and a strong adhesive force towards water. The static water contact angle is larger than 150° and the adhesive force to water is about 66 μN. The resultant gecko-inspired polyimide film can be used as a "mechanical hand" to snatch micro-liter liquids. We expect this work will provide the inspiration to reveal the mechanism of the high-adhesive superhydrophobic of geckos and extend the practical applications of polyimide materials. PMID:22139414

  4. Path planning versus cue responding: a bio-inspired model of switching between navigation strategies.

    PubMed

    Dollé, Laurent; Sheynikhovich, Denis; Girard, Benoît; Chavarriaga, Ricardo; Guillot, Agnès

    2010-10-01

    In this article, we describe a new computational model of switching between path-planning and cue-guided navigation strategies. It is based on three main assumptions: (i) the strategies are mediated by separate memory systems that learn independently and in parallel; (ii) the learning algorithms are different in the two memory systems-the cue-guided strategy uses a temporal-difference (TD) learning rule to approach a visible goal, whereas the path-planning strategy relies on a place-cell-based graph-search algorithm to learn the location of a hidden goal; (iii) a strategy selection mechanism uses TD-learning rule to choose the most successful strategy based on past experience. We propose a novel criterion for strategy selection based on the directions of goal-oriented movements suggested by the different strategies. We show that the selection criterion based on this "common currency" is capable of choosing the best among TD-learning and planning strategies and can be used to solve navigational tasks in continuous state and action spaces. The model has been successfully applied to reproduce rat behavior in two water-maze tasks in which the two strategies were shown to interact. The model was used to analyze competitive and cooperative interactions between different strategies during these tasks as well as relative influence of different types of sensory cues. PMID:20617443

  5. A new bio-inspired perceptual control architecture applied to solving navigation tasks

    NASA Astrophysics Data System (ADS)

    Arena, P.; De Fiore, S.; Patané, L.; Vitanza, A.

    2009-05-01

    In this paper a new general purpose perceptual control architecture is presented and applied to robot navigation in cluttered environments. In nature, insects show the ability to react to certain stimuli with simple reflexes using direct sensory-motor pathways, which can be considered as basic behaviors, while high brain regions provide secondary pathway allowing the emergence of a cognitive behavior which modulates the basic abilities. Taking inspiration from this evidence, our architecture modulates, through a reinforcement learning, a set of competitive and concurrent basic behaviors in order to accomplish the task assigned through a reward function. The core of the architecture is constituted by the Representation layer, where different stimuli, triggering competitive reflexes, are fused to form a unique abstract picture of the environment. The representation is formalized by means of Reaction-Diffusion nonlinear partial differential equations, under the paradigm of the Cellular Neural Networks, whose dynamics converges to steady-state Turing patterns. A suitable unsupervised learning, introduced at the afferent (input) stage, leads to the shaping of the basins of attractions of the Turing patterns in order to incrementally drive the association between sensor stimuli and patterns. In this way, at the end of the leaning stage, each pattern is characteristic of a particular behavior modulation, while its trained basin of attraction contains the set of all the environment conditions, as recorded through the sensors, leading to the emergence of that particular behavior modulation. Robot simulations are reported to demonstrate the potentiality and the effectiveness of the approach.

  6. Bio-inspired multifunctional catecholic assembly for photo-programmable biointerface.

    PubMed

    Huang, Chun-Jen; Wang, Lin-Chuan

    2015-10-01

    This article reports a novel multifunctional mussel-inspired zwitterionic catecholic assembly to form a photoresponsive biointerface. The assembly is the combination of the antifouling sulfobetaine and photocleavable o-nitrophenyl moieties into a molecule, becoming sulfobetaine nitrodopamine (SB-nDA). We demonstrated the formation of a compact thin SB-nDA film on TiO₂ by using the pH transition approach. The film thickness, surface wettability and elemental composition were characterized using ellipsometry, contact angle goniometer, atomic force microscopy and X-ray photoelectron spectroscopy, respectively. The SB-nDA thin films can effectively resist adhesion of both Gram-positive Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa by more than 95% relative to bare TiO₂. Quartz crystal microbalance with dissipation (QCM-D) sensor was employed for protein fouling tests, showing the comparable antifouling property of SB-nDA with thiol- or silane-based surface ligands. More importantly, the spatiotemporal control over the bioinertness by UV irradiation has been studied with bacterial and protein adsorption. Therefore, the catecholic chemistry can be used for programmable tailoring of interfacial properties, permitting potential application in light-guided targeting for nanomedicine. PMID:26208296

  7. The Wright Brothers and the Future of Bio-Inspired Flight: 1899 through to the Future

    NASA Technical Reports Server (NTRS)

    Bowers, Albion

    2007-01-01

    This viewgraph presentation reviews the experiments that the Wright Brothers conducted prior to their first powered flight in 1903 to developing the first practical aircraft in 1905. Many pictures of the gliders and other devices are used to illustrate the gradual development and experimentation that proceeded the first powered flight.

  8. Lessons from Nature: A Bio-Inspired Approach to Molecular Design.

    PubMed

    Cook, Sarah A; Hill, Ethan A; Borovik, A S

    2015-07-14

    Metalloproteins contain actives sites with intricate structures that perform specific functions with high selectivity and efficiency. The complexity of these systems complicates the study of their function and the understanding of the properties that give rise to their reactivity. One approach that has contributed to the current level of understanding of their biological function is the study of synthetic constructs that mimic one or more aspects of the native metalloproteins. These systems allow individual contributions to the structure and function to be analyzed and also permit spectroscopic characterization of the metal cofactors without complications from the protein environment. This Current Topic is a review of synthetic constructs as probes for understanding the biological activation of small molecules. These topics are developed from the perspective of seminal molecular design breakthroughs from the past that provide the foundation for the systems used today. PMID:26079379

  9. Fracture mode control: a bio-inspired strategy to combat catastrophic damage

    PubMed Central

    Yao, Haimin; Xie, Zhaoqian; He, Chong; Dao, Ming

    2015-01-01

    The excellent mechanical properties of natural biomaterials have attracted intense attention from researchers with focus on the strengthening and toughening mechanisms. Nevertheless, no material is unconquerable under sufficiently high load. If fracture is unavoidable, constraining the damage scope turns to be a practical way to preserve the integrity of the whole structure. Recent studies on biomaterials have revealed that many structural biomaterials tend to be fractured, under sufficiently high indentation load, through ring cracking which is more localized and hence less destructive compared to the radial one. Inspired by this observation, here we explore the factors affecting the fracture mode of structural biomaterials idealized as laminated materials. Our results suggest that fracture mode of laminated materials depends on the coating/substrate modulus mismatch and the indenter size. A map of fracture mode is developed, showing a critical modulus mismatch (CMM), below which ring cracking dominates irrespective of the indenter size. Many structural biomaterials in nature are found to have modulus mismatch close to the CMM. Our results not only shed light on the mechanics of inclination to ring cracking exhibited by structural biomaterials but are of great value to the design of laminated structures with better persistence of structural integrity. PMID:25619564

  10. Improved performance of protected catecholic polysiloxanes for bio-inspired wet adhesion to surface oxides

    PubMed Central

    Heo, Jinhwa; Kang, Taegon; Jang, Se Gyu; Hwang, Dong Soo; Spruell, Jason M.; Killops, Kato L.; Waite, J. Herbert; Hawker, Craig J.

    2012-01-01

    A facile synthetic strategy for introducing catecholic moieties into polymeric materials based on a readily available precursor – eugenol – and efficient chemistries – tris(pentafluorophenyl)borane catalyzed silation and thiol-ene coupling is reported. Silyl-protection is shown to be critical for the oxidative stability of catecholic moieties during synthesis and processing which allows functionalized polysiloxane derivatives to be fabricated into 3-D microstructures as well as 2-D patterned surfaces. Deprotection gives stable catechol surfaces with adhesion to a variety of oxide surfaces being precisely tuned by the level of catechol incorporation. The advantage of silyl-protection for catechol functionalized polysiloxanes is demonstrated and represents a promising and versatile new platform for underwater surface treatments. PMID:23181614

  11. A bio-inspired device for drag reduction on a three-dimensional model vehicle.

    PubMed

    Kim, Dongri; Lee, Hoon; Yi, Wook; Choi, Haecheon

    2016-04-01

    In this paper, we introduce a bio-mimetic device for the reduction of the drag force on a three-dimensional model vehicle, the Ahmed body (Ahmed et al 1984 SAE Technical Paper 840300). The device, called automatic moving deflector (AMD), is designed inspired by the movement of secondary feathers on bird's wing suction surface: i.e., secondary feathers pop up when massive separation occurs on bird's wing suction surface at high angles of attack, which increases the lift force at landing. The AMD is applied to the rear slanted surface of the Ahmed body to control the flow separation there. The angle of the slanted surface considered is 25° at which the drag coefficient on the Ahmed body is highest. The wind tunnel experiment is conducted at Re H  = 1.0 × 10(5)-3.8 × 10(5), based on the height of the Ahmed body (H) and the free-stream velocity (U ∞). Several AMDs of different sizes and materials are tested by measuring the drag force on the Ahmed body, and showed drag reductions up to 19%. The velocity and surface-pressure measurements show that AMD starts to pop up when the pressure in the thin gap between the slanted surface and AMD is much larger than that on the upper surface of AMD. We also derive an empirical formula that predicts the critical free-stream velocity at which AMD starts to operate. Finally, it is shown that the drag reduction by AMD is mainly attributed to a pressure recovery on the slanted surface by delaying the flow separation and suppressing the strength of the longitudinal vortices emanating from the lateral edges of the slanted surface. PMID:26963693

  12. Bio-inspired detoxification using 3D-printed hydrogel nanocomposites

    NASA Astrophysics Data System (ADS)

    Gou, Maling; Qu, Xin; Zhu, Wei; Xiang, Mingli; Yang, Jun; Zhang, Kang; Wei, Yuquan; Chen, Shaochen

    2014-05-01

    Rationally designed nanoparticles that can bind toxins show great promise for detoxification. However, the conventional intravenous administration of nanoparticles for detoxification often leads to nanoparticle accumulation in the liver, posing a risk of secondary poisoning especially in liver-failure patients. Here we present a liver-inspired three-dimensional (3D) detoxification device. This device is created by 3D printing of designer hydrogels with functional polydiacetylene nanoparticles installed in the hydrogel matrix. The nanoparticles can attract, capture and sense toxins, while the 3D matrix with a modified liver lobule microstructure allows toxins to be trapped efficiently. Our results show that the toxin solution completely loses its virulence after treatment using this biomimetic detoxification device. This work provides a proof-of-concept of detoxification by a 3D-printed biomimetic nanocomposite construct in hydrogel, and could lead to the development of alternative detoxification platforms.

  13. Bio-inspired device: a novel smart MR spring featuring tendril structure

    NASA Astrophysics Data System (ADS)

    Kaluvan, Suresh; Park, Chun-Yong; Choi, Seung-Bok

    2016-01-01

    Smart materials such as piezoelectric patches, shape memory alloy, electro and magneto rheological fluid, magnetostrictive materials, etc are involved by far to design intelligent and high performance smart devices like injectors, dental braces, dampers, actuators and sensors. In this paper, an interesting smart device is proposed by inspiring on the structure of the bio climber plant. The key enabling concept of this proposed work is to design the smart spring damper as a helical shaped tendril structure using magneto-rheological (MR) fluid. The proposed smart spring consists of a hollow helical structure filled with MR fluid. The viscosity of the MR fluid decides the damping force of helical shaped smart spring, while the fluid intensity in the vine decides the strength of the tendril in the climber plant. Thus, the proposed smart spring can provide a new concept design of the damper which can be applicable to various damping system industries with tuneable damping force. The proposed smart spring damper has several advantageous such as cost effective, easy implementation compared with the conventional damper. In addition, the proposed spring damper can be easily designed to adapt different damping force levels without any alteration.

  14. Bio-inspired modeling and implementation of the ocelli visual system of flying insects.

    PubMed

    Gremillion, Gregory; Humbert, J Sean; Krapp, Holger G

    2014-12-01

    Two visual sensing modalities in insects, the ocelli and compound eyes, provide signals used for flight stabilization and navigation. In this article, a generalized model of the ocellar visual system is developed for a 3-D visual simulation environment based on behavioral, anatomical, and electrophysiological data from several species. A linear measurement model is estimated from Monte Carlo simulation in a cluttered urban environment relating state changes of the vehicle to the outputs of the ocellar model. A fully analog-printed circuit board sensor based on this model is designed and fabricated. Open-loop characterization of the sensor to visual stimuli induced by self motion is performed. Closed-loop stabilizing feedback of the sensor in combination with optic flow sensors is implemented onboard a quadrotor micro-air vehicle and its impulse response is characterized. PMID:25217116

  15. The development of a lightweight modular compliant surface bio-inspired robot

    NASA Astrophysics Data System (ADS)

    Stone, David L.; Cranney, John

    2004-09-01

    The DARPA Sponsored Compliant Surface Robotics (CSR) program pursues development of a high mobility, lightweight, modular, morphable robot for military forces in the field and for other industrial uses. The USTLAB effort builds on proof of concept feasibility studies and demonstration of a 4, 6, or 8 wheeled modular vehicle with articulated leg-wheel assemblies. In Phase I, basic open plant stability was proven for climbing over obstacles of ~18 inches high and traversing ~75 degree inclines (up, down, or sideways) in a platform of approximately 15 kilograms. At the completion of Phase II, we have completed mechanical and electronics engineering design and achieved changes which currently enable future work in active articulation, enabling autonomous reconfiguration for a wide variety of terrains, including upside down operations (in case of flip over), and we have reduced platform weight by one third. Currently the vehicle weighs 10 kilograms and will grow marginally as additional actuation, MEMS based organic sensing, payload, and autonomous processing is added. The CSR vehicle"s modular spider-like configuration facilitates adaptation to many uses and compliance over rugged terrain. The developmental process and the vehicle characteristics will be discussed.

  16. Bio-inspired vapor-responsive colloidal photonic crystal patterns by inkjet printing.

    PubMed

    Bai, Ling; Xie, Zhuoying; Wang, Wei; Yuan, Chunwei; Zhao, Yuanjin; Mu, Zhongde; Zhong, Qifeng; Gu, Zhongze

    2014-11-25

    Facile, fast, and cost-effective technology for patterning of responsive colloidal photonic crystals (CPCs) is of great importance for their practical applications. In this report, we develop a kind of responsive CPC patterns with multicolor shifting properties by inkjet printing mesoporous colloidal nanoparticle ink on both rigid and soft substrates. By adjusting the size and mesopores' proportion of nanoparticles, we can precisely control the original color and vapor-responsive color shift extent of mesoporous CPC. As a consequence, multicolor mesoporous CPCs patterns with complex vapor responsive color shifts or vapor-revealed implicit images are subsequently achieved. The complicated and reversible multicolor shifts of mesoporous CPC patterns are favorable for immediate recognition by naked eyes but hard to copy. This approach is favorable for integration of responsive CPCs with controllable responsive optical properties. Therefore, it is of great promise for developing advanced responsive CPC devices such as anticounterfeiting devices, multifunctional microchips, sensor arrays, or dynamic displays. PMID:25300045

  17. Teaching Bio-inspired design using heart and circulatory system as a model

    NASA Astrophysics Data System (ADS)

    Gharib, Morteza

    2007-11-01

    Cardiovasculr system is an open book of design for an engineer searching for innovation in the particular area of efficient fluid transport. But the routs of technology transfer from nature's technology to engineering science are not always so obvious. The main challenge is how to train our future students to find these hidden innovations and apply them based on sound engineering and scientific principles. As part of a 3 quarter course at Caltech that is called ``Physiology for Bioengineers,'' we try to discuss examples of such cases by introducing students to the critical thinking that is required for model development. In this talk, I will give two examples from the third quarter of this course where students are asked to develop a physics-based model to describe the efficient pumping of blood in embryonic and adult hearts.

  18. Autonomous self-healing structural composites with bio-inspired design

    PubMed Central

    D’Elia, Eleonora; Eslava, Salvador; Miranda, Miriam; Georgiou, Theoni K.; Saiz, Eduardo

    2016-01-01

    Strong and tough natural composites such as bone, silk or nacre are often built from stiff blocks bound together using thin interfacial soft layers that can also provide sacrificial bonds for self-repair. Here we show that it is possible exploit this design in order to create self-healing structural composites by using thin supramolecular polymer interfaces between ceramic blocks. We have built model brick-and-mortar structures with ceramic contents above 95 vol% that exhibit strengths of the order of MPa (three orders of magnitude higher than the interfacial polymer) and fracture energies that are two orders of magnitude higher than those of the glass bricks. More importantly, these properties can be fully recovered after fracture without using external stimuli or delivering healing agents. This approach demonstrates a very promising route towards the design of strong, ideal self-healing materials able to self-repair repeatedly without degradation or external stimuli. PMID:27146382

  19. Adaptive Bio-Inspired Wireless Network Routing for Planetary Surface Exploration

    NASA Technical Reports Server (NTRS)

    Alena, Richard I.; Lee, Charles

    2004-01-01

    Wireless mobile networks suffer connectivity loss when used in a terrain that has hills, and valleys when line of sight is interrupted or range is exceeded. To resolve this problem and achieve acceptable network performance, we have designed an adaptive, configurable, hybrid system to automatically route network packets along the best path between multiple geographically dispersed modules. This is very useful in planetary surface exploration, especially for ad-hoc mobile networks, where computational devices take an active part in creating a network infrastructure, and can actually be used to route data dynamically and even store data for later transmission between networks. Using inspiration from biological systems, this research proposes to use ant trail algorithms with multi-layered information maps (topographic maps, RF coverage maps) to determine the best route through ad-hoc network at real time. The determination of best route is a complex one, and requires research into the appropriate metrics, best method to identify the best path, optimizing traffic capacity, network performance, reliability, processing capabilities and cost. Real ants are capable of finding the shortest path from their nest to a food source without visual sensing through the use of pheromones. They are also able to adapt to changes in the environment using subtle clues. To use ant trail algorithms, we need to define the probability function. The artificial ant is, in this case, a software agent that moves from node to node on a network graph. The function to calculate the fitness (evaluate the better path) includes: length of the network edge, the coverage index, topology graph index, and pheromone trail left behind by other ant agents. Each agent modifies the environment in two different ways: 1) Local trail updating: As the ant moves between nodes it updates the amount of pheromone on the edge; and 2) Global trail updating: When all ants have completed a tour the ant that found the shortest route updates the edges in its path.

  20. Bio-inspired mineralization of hydroxyapatite in 3D silk fibroin hydrogel for bone tissue engineering.

    PubMed

    Jin, Yashi; Kundu, Banani; Cai, Yurong; Kundu, Subhas C; Yao, Juming

    2015-10-01

    To fabricate hard tissue implants with bone-like structure using a biomimetic mineralization method is drawing much more attentions in bone tissue engineering. The present work focuses in designing 3D silk fibroin hydrogel to modulate the nucleation and growth of hydroxyapatite crystals via a simple ion diffusion method. The study indicates that Ca(2+) incorporation within the hydrogel provides the nucleation sites for hydroxyapatite crystals and subsequently regulates their oriented growth. The mineralization process is regulated in a Ca(2+) concentration- and minerlization time-dependent way. Further, the compressive strength of the mineralized hydrogels is directly proportional with the mineral content in hydrogel. The orchestrated organic/inorganic composite supports well the viability and proliferation of human osteoblast cells; improved cyto-compatibility with increased mineral content. Together, the present investigation reports a simple and biomimetic process to fabricate 3D bone-like biomaterial with desired efficacy to repair bone defects. PMID:26209967

  1. Bio-Inspired Pressure Sensitive Foam Arrays for use in Hydrodynamic Sensing Applications

    NASA Astrophysics Data System (ADS)

    Dusek, Jeff; Triantafyllou, Michael; Lang, Jeffrey

    2015-11-01

    Shallow, turbid, and highly dynamic coastal waters provide a challenging environment for safe and reliable operation of marine vehicles faced with a distinct environmentally driven perceptual deficit. In nature, fish have solved this perplexing sensory problem and exhibit an intimate knowledge of the near-body flow field. This enhanced perception is mediated by the ability to discern and interpret hydrodynamic flow structures through the velocity and pressure sensing capabilities of the fish's lateral line. Taking cues from biological sensory principles, highly conformal pressure sensor arrays have been developed utilizing a novel piezoresistive carbon black-PDMS foam active material. By leveraging the low Young's modulus and watertight structure of closed-cell PDMS (silicone) foam, the sensor arrays are well suited for hydrodynamic sensing applications and prolonged exposure to fluid environments. Prototype arrays were characterized experimentally using hydrodynamic stimuli inspired by biological flows, and were found to exhibit a high degree of sensitivity while improving on the flexibility, robustness, and cost of existing pressure sensors.

  2. Smart nanosystems: Bio-inspired technologies that interact with the host environment

    PubMed Central

    Kwon, Ester J.; Lo, Justin H.; Bhatia, Sangeeta N.

    2015-01-01

    Nanoparticle technologies intended for human administration must be designed to interact with, and ideally leverage, a living host environment. Here, we describe smart nanosystems classified in two categories: (i) those that sense the host environment and respond and (ii) those that first prime the host environment to interact with engineered nanoparticles. Smart nanosystems have the potential to produce personalized diagnostic and therapeutic schema by using the local environment to drive material behavior and ultimately improve human health. PMID:26598694

  3. Polypyrrole-supported membrane proteins for bio-inspired ion channels.

    PubMed

    Pérez-Madrigal, Maria M; del Valle, Luis J; Armelin, Elaine; Michaux, Catherine; Roussel, Guillaume; Perpète, Eric A; Alemán, Carlos

    2015-01-28

    Biomedical platforms constructed by immobilizing membrane proteins in matrixes made of synthetic organic polymers is a challenge because the structure and function of these proteins are affected by environmental conditions. In this work, an operative composite that regulates the diffusion of alkali ions has been prepared by functionalizing a supporting matrix made of poly(N-methylpyrrole) (PNMPy) with a β-barrel membrane protein (Omp2a) that forms channels and pores. The protein has been unequivocally identified in the composite, and its structure has been shown to remain unaltered. The PNMPy-Omp2a platform fulfills properties typically associated with functional bio-interfaces with biomedical applications (e.g., biocompatibility, biodegrabadility, and hydrophilicity). The functionality of the immobilized protein has been examined by studying the passive ion transport response in the presence of electrolytic solutions with Na(+) and K(+) concentrations close to those found in blood. Although the behavior of PNMPy and PNMPy-Omp2a is very similar for solutions with very low concentration, the resistance of the latter decreases drastically when the concentration of ions increases to ∼100 mM. This reduction reflects an enhanced ion exchange between the biocomposite and the electrolytic medium, which is not observed in PNMPy, evidencing that PNMPy-Omp2a is particularly well suited to prepare bioinspired channels and smart biosensors. PMID:25585165

  4. Autonomous self-healing structural composites with bio-inspired design

    NASA Astrophysics Data System (ADS)

    D’Elia, Eleonora; Eslava, Salvador; Miranda, Miriam; Georgiou, Theoni K.; Saiz, Eduardo

    2016-05-01

    Strong and tough natural composites such as bone, silk or nacre are often built from stiff blocks bound together using thin interfacial soft layers that can also provide sacrificial bonds for self-repair. Here we show that it is possible exploit this design in order to create self-healing structural composites by using thin supramolecular polymer interfaces between ceramic blocks. We have built model brick-and-mortar structures with ceramic contents above 95 vol% that exhibit strengths of the order of MPa (three orders of magnitude higher than the interfacial polymer) and fracture energies that are two orders of magnitude higher than those of the glass bricks. More importantly, these properties can be fully recovered after fracture without using external stimuli or delivering healing agents. This approach demonstrates a very promising route towards the design of strong, ideal self-healing materials able to self-repair repeatedly without degradation or external stimuli.

  5. Autonomous self-healing structural composites with bio-inspired design.

    PubMed

    D'Elia, Eleonora; Eslava, Salvador; Miranda, Miriam; Georgiou, Theoni K; Saiz, Eduardo

    2016-01-01

    Strong and tough natural composites such as bone, silk or nacre are often built from stiff blocks bound together using thin interfacial soft layers that can also provide sacrificial bonds for self-repair. Here we show that it is possible exploit this design in order to create self-healing structural composites by using thin supramolecular polymer interfaces between ceramic blocks. We have built model brick-and-mortar structures with ceramic contents above 95 vol% that exhibit strengths of the order of MPa (three orders of magnitude higher than the interfacial polymer) and fracture energies that are two orders of magnitude higher than those of the glass bricks. More importantly, these properties can be fully recovered after fracture without using external stimuli or delivering healing agents. This approach demonstrates a very promising route towards the design of strong, ideal self-healing materials able to self-repair repeatedly without degradation or external stimuli. PMID:27146382

  6. Bio-inspired durable, superhydrophobic magnetic particles for oil/water separation.

    PubMed

    Zhang, Liang; Li, Lili; Dang, Zhi-Min

    2016-02-01

    In the present study, superhydrophobic and superoleophilic microparticles with magnetic property were fabricated by combining the oxidation and self-polymerization of dopamine and formation of Fe3O4 nanoparticles on the surface of the polydopamine (PDA) particles, followed by modification with low surface energy material. The modified PDA/Fe3O4 particles showed high water repellency with contact angle (CA) measured at 153.7±1.6° and high oil affinity. The superhydrophobic microparticles preserved high water CA after aging test, showing excellent durability. The microparticles were employed to effectively remove oil from water in different routes. Superhydrophobic sponge was prepared by modifying with the achieved microparticles. The sponge exhibited high absorption capability of oil, with weight gains ranging from 1348% to 7268%. The results suggest this work might provide a promising candidate for oily pollutants/water separation and transportation. PMID:26550784

  7. Bio-Inspired Synthetic Nanovesicles for Glucose-Responsive Release of Insulin

    PubMed Central

    2015-01-01

    A new glucose-responsive formulation for self-regulated insulin delivery was constructed by packing insulin, glucose-specific enzymes into pH-sensitive polymersome-based nanovesicles assembled by a diblock copolymer. Glucose can passively transport across the bilayer membrane of the nanovesicle and be oxidized into gluconic acid by glucose oxidase, thereby causing a decrease in local pH. The acidic microenvironment causes the hydrolysis of the pH sensitive nanovesicle that in turn triggers the release of insulin in a glucose responsive fashion. In vitro studies validated that the release of insulin from nanovesicle was effectively correlated with the external glucose concentration. In vivo experiments, in which diabetic mice were subcutaneously administered with the nanovesicles, demonstrate that a single injection of the developed nanovesicle facilitated stabilization of the blood glucose levels in the normoglycemic state (<200 mg/dL) for up to 5 days. PMID:25268758

  8. Bio-inspired Cryo-ink Preserves Red Blood Cell Phenotype and Function during Nanoliter Vitrification

    PubMed Central

    Assal, Rami El; Guven, Sinan; Gurkan, Umut Atakan; Gozen, Irep; Shafiee, Hadi; Dalbeyber, Sedef; Abdalla, Noor; Thomas, Gawain; Fuld, Wendy; Illigens, Ben M.W.; Estanislau, Jessica; Khoory, Joseph; Kaufman, Richard; Zylberberg, Claudia; Lindeman, Neal; Wen, Qi; Ghiran, Ionita; Demirci, Utkan

    2014-01-01

    Current red blood cell cryopreservation methods utilize bulk volumes, causing cryo-injury of cells, which results in irreversible disruption of cell morphology, mechanics, and function. An innovative approach to preserve human red blood cell morphology, mechanics, and function following vitrification in nanoliter volumes is developed using a novel cryo-ink integrated with a bio-printing approach. PMID:25047246

  9. Bio-inspired Gecko Micro-surface for Drag Reduction in Turbulent Flows

    NASA Astrophysics Data System (ADS)

    Arenas, Isnardo; Carrasquillo, Kenneth; Araya, Guillermo; Castillo, Luciano; Leonardi, Stefano

    2014-11-01

    Direct Numerical Simulations of a turbulent channel flow with a porous wall inspired from the Gecko lizard were performed at Reynolds number of Reτ = 450 . Two superposed fluids were considered. As initial condition, one fluid fills the microfibrillar surface, the interface with the overlying fluid being flat and corresponding to the crests plane. The code is based on a finite difference scheme with a Runge Kutta and fractional step. The porous wall is modeled with the immersed boundary method, while the dynamic of the interface between the two fluids is solved with a level set method. A parametric study has been performed varying the viscosity ratio between the two fluids. Two cases have been considered, with and without surface tension. Without surface tension the microfibrillar wall acts as a rough wall increasing the drag. However, when the surface tension is large enough to maintain the interface stable, the external fluid cannot enter into the porous wall and an effective slip is produced. When the fluid in the porous wall has a viscosity 100 times smaller than that of the overlying fluid, a drag reduction of about 60 % can be observed. In this case, the near wall coherent structures become significantly weaker. The numerical simulations were performed on XSEDE TACC under Grant No. CTS070066. S.L., I.A. and K.C. were supported by ONR MURI grant.

  10. Bio-inspired, low-cost, self-regulating valves for drip irrigation in developing countries

    NASA Astrophysics Data System (ADS)

    Zimoch, Pawel; Tixier, Eliott; Hosoi, Anette; Winter, Amos

    2012-11-01

    We use nonlinear behavior of thin-walled structures - an approach inspired by biological systems (the human airway, for example) - to address one of the most important problems facing subsistence farmers in developing countries : lack of access to inexpensive, water-efficient irrigation systems. An effective way of delivering water to crops is through a network of drippers, with up to 85% of the water delivered being absorbed by plants. However, of the 140 m hectares of cropped land in India, only 61 m are irrigated and just 5 m through drip irrigation. This is, in part, due to the relatively high cost of drip irrigation. The main cost comes from the requirement to pump the water at relatively high pressure (>1 bar), to minimize the effect of uneven terrain and viscous losses in the network, and ensure that each plant receives the same amount of water. We demonstrate that the pressure required to drive the system can be reduced significantly by using thin-walled structures to design drippers with completely passive self-regulation that activates at approximately 0.1 bar. We also report on our work towards reducing the overall price of drip irrigation systems by as much as 90%, and making them more affordable for 800 million subsistence farmers worldwide.

  11. Bio-Inspired Structural Colors Produced via Self-Assembly of Synthetic Melanin Nanoparticles.

    PubMed

    Xiao, Ming; Li, Yiwen; Allen, Michael C; Deheyn, Dimitri D; Yue, Xiujun; Zhao, Jiuzhou; Gianneschi, Nathan C; Shawkey, Matthew D; Dhinojwala, Ali

    2015-05-26

    Structural colors arising from interactions of light with submicron scale periodic structures have been found in many species across all taxa, serving multiple biological functions including sexual signaling, camouflage, and aposematism. Directly inspired by the extensive use of self-assembled melanosomes to produce colors in avian feathers, we set out to synthesize and assemble polydopamine-based synthetic melanin nanoparticles in an effort to fabricate colored films. We have quantitatively demonstrated that synthetic melanin nanoparticles have a high refractive index and broad absorption spanning across the UV-visible range, similar to natural melanins. Utilizing a thin-film interference model, we demonstrated the coloration mechanism of deposited films and showed that the unique optical properties of synthetic melanin nanoparticles provide advantages for structural colors over other polymeric nanoparticles (i.e., polystyrene colloidal particles). PMID:25938924

  12. Compiling probabilistic, bio-inspired circuits on a field programmable analog array

    PubMed Central

    Marr, Bo; Hasler, Jennifer

    2014-01-01

    A field programmable analog array (FPAA) is presented as an energy and computational efficiency engine: a mixed mode processor for which functions can be compiled at significantly less energy costs using probabilistic computing circuits. More specifically, it will be shown that the core computation of any dynamical system can be computed on the FPAA at significantly less energy per operation than a digital implementation. A stochastic system that is dynamically controllable via voltage controlled amplifier and comparator thresholds is implemented, which computes Bernoulli random variables. From Bernoulli variables it is shown exponentially distributed random variables, and random variables of an arbitrary distribution can be computed. The Gillespie algorithm is simulated to show the utility of this system by calculating the trajectory of a biological system computed stochastically with this probabilistic hardware where over a 127X performance improvement over current software approaches is shown. The relevance of this approach is extended to any dynamical system. The initial circuits and ideas for this work were generated at the 2008 Telluride Neuromorphic Workshop. PMID:24847199

  13. Compiling probabilistic, bio-inspired circuits on a field programmable analog array.

    PubMed

    Marr, Bo; Hasler, Jennifer

    2014-01-01

    A FIELD PROGRAMMABLE ANALOG ARRAY (FPAA) IS PRESENTED AS AN ENERGY AND COMPUTATIONAL EFFICIENCY ENGINE: a mixed mode processor for which functions can be compiled at significantly less energy costs using probabilistic computing circuits. More specifically, it will be shown that the core computation of any dynamical system can be computed on the FPAA at significantly less energy per operation than a digital implementation. A stochastic system that is dynamically controllable via voltage controlled amplifier and comparator thresholds is implemented, which computes Bernoulli random variables. From Bernoulli variables it is shown exponentially distributed random variables, and random variables of an arbitrary distribution can be computed. The Gillespie algorithm is simulated to show the utility of this system by calculating the trajectory of a biological system computed stochastically with this probabilistic hardware where over a 127X performance improvement over current software approaches is shown. The relevance of this approach is extended to any dynamical system. The initial circuits and ideas for this work were generated at the 2008 Telluride Neuromorphic Workshop. PMID:24847199

  14. Investigation of a bio-inspired lift-enhancing effector on a 2D airfoil.

    PubMed

    Johnston, Joe; Gopalarathnam, Ashok

    2012-09-01

    A flap mounted on the upper surface of an airfoil, called a 'lift-enhancing effector', has been shown in wind tunnel tests to have a similar function to a bird's covert feathers, which rise off the wing's surface in response to separated flows. The effector, fabricated from a thin Mylar sheet, is allowed to rotate freely about its leading edge. The tests were performed in the NCSU subsonic wind tunnel at a chord Reynolds number of 4 × 10(5). The maximum lift coefficient with the effector was the same as that for the clean airfoil, but was maintained over an angle-of-attack range from 12° to almost 20°, resulting in a very gentle stall behavior. To better understand the aerodynamics and to estimate the deployment angle of the free-moving effector, fixed-angle effectors fabricated out of stiff wood were also tested. A progressive increase in the stall angle of attack with increasing effector angle was observed, with diminishing returns beyond the effector angle of 60°. Drag tests on both the free-moving and fixed effectors showed a marked improvement in drag at high angles of attack. Oil flow visualization on the airfoil with and without the fixed-angle effectors proved that the effector causes the separation point to move aft on the airfoil, as compared to the clean airfoil. This is thought to be the main mechanism by which an effector improves both lift and drag. A comparison of the fixed-effector results with those from the free-effector tests shows that the free effector's deployment angle is between 30° and 45°. When operating at and beyond the clean airfoil's stall angle, the free effector automatically deploys to progressively higher angles with increasing angles of attack. This slows down the rapid upstream movement of the separation point and avoids the severe reduction in the lift coefficient and an increase in the drag coefficient that are seen on the clean airfoil at the onset of stall. Thus, the effector postpones the stall by 4-8° and makes the stall behavior more gentle. The benefits of using the effector could include care-free operations at high angles of attack during perching and maneuvering flight, especially in gusty conditions. PMID:22498691

  15. Bio-inspired network optimization in soft materials — Insights from the plant cell wall

    NASA Astrophysics Data System (ADS)

    Vincent, R. R.; Cucheval, A.; Hemar, Y.; Williams, M. A. K.

    2009-01-01

    The dynamic-mechanical responses of ionotropic gels made from the biopolymer pectin have recently been investigated by microrheological experiments and found to exhibit behaviour indicative of semi-flexible polymer networks. In this work we investigate the gelling behaviour of pectin systems in which an enzyme (pectinmethylesterase, PME) is used to liberate ion-binding sites on initially inert polymers, while in the presence of ions. This is in contrast to the previous work, where it was the release of ions (rather than ion-binding groups) that was controlled and the polymers had pre-existing cross-linkable moieties. In stark contrast to the semi-flexible network paradigm of biological gels and the previous work on pectin, the gels studied herein exhibit the properties of chemically cross-linked networks of flexible polymers.

  16. Experimental investigation of bio inspired flapping wings for MAV and NAV applications

    NASA Astrophysics Data System (ADS)

    Gopa Kumar, Anand

    2009-11-01

    The current investigation focuses on achieving a greater understanding on the aerodynamic phenomena that takes place during flapping flight and its application in the development of Micro Air Vehicles (MAVs) and Nano Air Vehicles (NAVs). Quantitative force measurements were made on the MAV model to understand its aerodynamic performance of flapping wings at different operational flight conditions. A comparative analysis was also made to understand the effects of wing membrane flexibility on the aerodynamic performance of an MAV. The results obtained from this study would help design a membrane based flapping wings which would have an optimum aerodynamic performance. Dragonflies are considered to be some of the most agile and maneuverable insects known to man due to which they taken as an inspiration for the study of flapping wing NAVs. Piezoelectric fans were used to simulate the flapping motion of insect wings due to their ability to generate a high wing beat frequency. Flow measurement studies on the fans placed in a tandem wing configuration were carried out with the help of Digital Particle Image Velocimetry (DPIV) by which quantitative flow field measurements were made. The PIV results provide a greater understanding of the vortex structures which were generated due to high frequency flapping motion of the wings.

  17. Bio-inspired sensitive and reversible mechanochromisms via strain-dependent cracks and folds.

    PubMed

    Zeng, Songshan; Zhang, Dianyun; Huang, Wenhan; Wang, Zhaofeng; Freire, Stephan G; Yu, Xiaoyuan; Smith, Andrew T; Huang, Emily Y; Nguon, Helen; Sun, Luyi

    2016-01-01

    A number of marine organisms use muscle-controlled surface structures to achieve rapid changes in colour and transparency with outstanding reversibility. Inspired by these display tactics, we develop analogous deformation-controlled surface-engineering approaches via strain-dependent cracks and folds to realize the following four mechanochromic devices: (1) transparency change mechanochromism (TCM), (2) luminescent mechanochromism (LM), (3) colour alteration mechanochromism (CAM) and (4) encryption mechanochromism (EM). These devices are based on a simple bilayer system that exhibits a broad range of mechanochromic behaviours with high sensitivity and reversibility. The TCM device can reversibly switch between transparent and opaque states. The LM can emit intensive fluorescence as stretched with very high strain sensitivity. The CAM can turn fluorescence from green to yellow to orange as stretched within 20% strain. The EM device can reversibly reveal and conceal any desirable patterns. PMID:27389480

  18. Reverse engineering the euglenoid movement: from unicellular swimmers to bio-inspired robots

    NASA Astrophysics Data System (ADS)

    Desimone, Antonio; Noselli, Giovanni; Arroyo, Marino

    Euglenids are unicelluar organisms living in freshwater, which are capable of moving either by beating a flagellum, or by executing dramatic shape changes. These are accomplished thanks to a complex structure made of interlocking pellicle strips, microtubules, and motor proteins. Relative sliding of the pellicle strips, suitably orchestrated, can cause the propagation of a bulge along the body, hence generating a propulsive force. We study the mechanisms by which the sliding of pellicle strips leads to shape control and locomotion, by means of both theory (through the mechanics of active surfaces and its coupling to computational fluid dynamics for the surrounding fluid) and experimental observations. Moreover, we implement them into a new concept of a surface with programmable shape, obtained by asssembling 3d-printed strips in a construct mimicking the biological template. We explore the range of possible geometries achievable by actuating these surfaces, to assess their potential in soft robotics applications. The subtle balance between constraints and flexibility leads to a wide variety of shapes that can be obtained with relatively simple controls, similar to the notion of morphological computation in biological systems. ERC Advanced Grant 340685 (MicroMotility).

  19. The role of mechanics in biological and bio-inspired systems

    NASA Astrophysics Data System (ADS)

    Egan, Paul; Sinko, Robert; Leduc, Philip R.; Keten, Sinan

    2015-07-01

    Natural systems frequently exploit intricate multiscale and multiphasic structures to achieve functionalities beyond those of man-made systems. Although understanding the chemical make-up of these systems is essential, the passive and active mechanics within biological systems are crucial when considering the many natural systems that achieve advanced properties, such as high strength-to-weight ratios and stimuli-responsive adaptability. Discovering how and why biological systems attain these desirable mechanical functionalities often reveals principles that inform new synthetic designs based on biological systems. Such approaches have traditionally found success in medical applications, and are now informing breakthroughs in diverse frontiers of science and engineering.

  20. Bio-Inspired Composite Interfaces: Controlling Hydrogel Mechanics via Polymer-Nanoparticle Coordination Bond Dynamics

    NASA Astrophysics Data System (ADS)

    Holten-Andersen, Niels

    2015-03-01

    In soft nanocomposite materials, the effective interaction between polymer molecules and inorganic nanoparticle surfaces plays a critical role in bulk mechanical properties. However, controlling these interfacial interactions remains a challenge. Inspired by the adhesive chemistry in mussel threads, we present a novel approach to control composite mechanics via polymer-particle interfacial dynamics; by incorporating iron oxide nanoparticles (Fe3O4 NPs) into a catechol-modified polymer network the resulting hydrogels are crosslinked via reversible coordination bonds at Fe3O4 NP surfaces thereby providing a dynamic gel network with robust self-healing properties. By studying the thermally activated composite network relaxation processes we have found that the polymer-NP binding energy can be controlled by engineering both the organic and inorganic side of the interface.