Due to the costliness of destructive evaluation methods for assessing the aging and shelf-life of missile and rocket components, the identification of nondestructive evaluation methods has become increasingly important to the Army. Verifying that there is a sufficient concentration of stabilizer is a dependable indicator that the missile’s double-based solid propellant is viable. The research outlined in this paper summarizes the Army Aviation and Missile Research, Development, and Engineering Center’s (AMRDEC’s) comparative use of nanoporous membranes, carbon nanotubes, and optical spectroscopic configured sensing techniques for detecting degradation in rocket motor propellant. The first sensing technique utilizes a gas collecting chamber consisting of nanoporous structures that trap the smaller solid propellant particles for measurement by a gas analysis device. In collaboration with NASA-Ames, sensing methods are developed that utilize functionalized single-walled carbon nanotubes as the key sensing element. The optical spectroscopic sensing method is based on a unique light collecting optical fiber system designed to detect the concentration of the propellant stabilizer. Experimental setups, laboratory results, and overall effectiveness of each technique are presented in this paper. Expectations are for the three sensing mechanisms to provide nondestructive evaluation methods that will offer cost-savings and improved weaponry health monitoring.

Successful technologies include objects, processes, and procedures that share a common theme; they are being used to generate new products that create economic growth. The foundation is the invention, but the invention is a small part of the overall effort. The pathway to success is understanding the competition, proper planning, record keeping, integrating a supply chain, understanding actual costs, intellectual property (IP), benchmarking, and timing. Additionally, there are obstacles that include financing, what to make, buy, and sell, and the division of labor i.e. recognizing who is best at what task. Over the past two decades, NASA Langley Research Center (LaRC) has developed several commercially available technologies. The approach to the commercialization of three of these inventions; Langley Research Center-Soluble Imide (LaRC-SI, Imitec Inc.), the Thin Layer Unimorph Driver (THUNDER, FACE International), and the Macrofiber Composite (MFC, Smart Material Corp.) will be described, as well as some of the lessons learned from the process. What makes these three inventions interesting is that one was created in the laboratory; another was built using the previous invention as part of its process, and the last one was created by packaging commercial-off-the-shelf (COTS) materials thereby creating a new component.

Football players are regularly exposed to violent impacts. Concussions are mild traumatic brain injuries that are one of the most common injuries experienced by football players. These concussions are often overlooked by football players themselves and the clinical criteria used to diagnose them. The cumulative effect of these mild traumatic brain injuries can cause long-term residual brain dysfunctions. In addition, an athlete’s fatigue level should be monitored to prevent any secondary injuries due to over exertion. Nitric Oxide acts as a metabolic adjustment factor that controls the flow of oxygen in blood and the contraction/relaxation of muscles. Fatigue can be evaluated by measuring the concentration change of nitric oxide in blood. However, measuring the concentration of nitric oxide in blood is not feasible during exercise. Nevertheless, the degree of fatigue can be measured with SpO2 during exercise because the change of nitric oxide also influences the SpO2. In this paper, we propose a wireless health monitoring helmet to diagnose concussions and evaluate fatigue in real time and on the field. The helmet is equipped with sensors and a transmitter module. As sensors, textile based electrodes are used to sense EEG and oximeter sensors are used to derive SpO2. The sensed physiological signals are amplified and processed in the transmitter module. The processed signals are transmitted to a server using Zigbee wireless communication. The EEG signals are classified to diagnose concussion or any abnormality of brain function. In conclusion, the system can monitor and diagnose concussions and evaluate fatigue in football players in real time by measuring their EEGs and SpO2.

Sudden cardiac death (SCD) and acute myocardial infarctions (AMIs) have been reported to be up to 7.6 times higher in rate of occurrence during intense exercise as compared to sedentary activities. The risk is high in individuals with both diagnosed as well as occult heart diseases. Recently, SCDs have been reported with a high rate of occurrence among young athletes and soldiers who routinely undergo vigorous training. Prescreening Electrocardiograms (ECG) and echocardiograms have been suggested as potential means of detecting any cardiac abnormalities prior to intense training to avoid the risk of SCDs, but the benefits of this approach are widely debated. Moreover, the increased risk of SCDs and AMIs during training or exercise suggests that ECGs are of much greater value when acquired real-time during the actual training. The availability of immediate diagnostic data will greatly reduce the time taken to administer the appropriate resuscitation. Important factors to consider in the implementation of this solution are: - cost of overall system, accuracy of signals acquired and unobtrusive design. In this paper, we evaluate a system using printed sensors made of inks with functional properties to acquire ECGs of athletes and soldiers during physical training and basic military training respectively. Using Zigbee, we show that athletes and soldiers can be monitored in real time, simultaneously.

Brain cells interfaced with electrical neural implants are utilized to gain a better understanding of the functionality of our nervous system. One main problem that exists with these neural implants is the potential to cause injury to surrounding neural cells due to a discrepancy in stiffness values between the implant and surrounding brain tissue when subjected to mechanical micromotion of the brain. To evaluate the effects of the mechanical mismatch, a series of dynamic simulations are conducted to better understand the design enhancements required to improve the feasibility of the neuron probe. In addition, the brain tissue deformation near the interface of the neuron probe can give insight on the extent of injury to the brain due to relative micromotion. The simulations use a nonlinear transient explicit finite element code, LS-DYNA. A three-dimensional quarter-symmetry finite element model is utilized for the transient analysis to capture the time-dependent dynamic deformations on the brain tissue from the implant as a function of different frequency shapes and stiffness values.

Wearable ECG(ElectroCardioGram) measurement systems have increasingly been developing for people who suffer from CVD(CardioVascular Disease) and have very active lifestyles. Especially, in the case of female CVD patients, several abnormal CVD symptoms are accompanied with CVDs. Therefore, monitoring women’s ECG signal is a significant diagnostic method to prevent from sudden heart attack. The E-bra ECG measurement system from our previous work provides more convenient option for women than Holter monitor system. The e-bra system was developed with a motion artifact removal algorithm by using an adaptive filter with LMS(least mean square) and a wandering noise baseline detection algorithm. In this paper, ICA(independent component analysis) algorithms are suggested to remove motion artifact factor for the e-bra system. Firstly, the ICA algorithms are developed with two kinds of statistical theories: Kurtosis, Endropy and evaluated by performing simulations with a ECG signal created by sgolayfilt function of MATLAB, a noise signal including 0.4Hz, 1.1Hz and 1.9Hz, and a weighed vector W estimated by kurtosis or entropy. A correlation value is shown as the degree of similarity between the created ECG signal and the estimated new ECG signal. In the real time E-Bra system, two pseudo signals are extracted by multiplying with a random weighted vector W, the measured ECG signal from E-bra system, and the noise component signal by noise extraction algorithm from our previous work. The suggested ICA algorithm basing on kurtosis or entropy is used to estimate the new ECG signal Y without noise component.

Semiconducting ZnO layer chemically grown on regenerated cellulose and its flexible paper transistor were studied. ZnO layer-cellulose composite was prepared by a simple chemical reaction process which included alkaline hydrolysis at low temperature lower than 100 °C and used wet regenerated cellulose as a hydrophilic substrate. By increasing the concentration of ZnO seeding layer on cellulose, the area of ZnO cluster also increases. In the low concentration conditions from 20 mM to 50 mM, it is observed that the average size of ZnO nanorods increases as the seeding concentration increases. However, flower-shaped ZnO structure is observed in higher concentration over 50 mM due to clustering effect during the growth of ZnO rods. Thin ZnO layer composed of nano-rods seemed to be grown well on regenerated cellulose and layer thickness of ZnO was well controlled by reaction time. Structural data of as grown ZnO/cellulose provides the crystal orientation-limited growth mechanism of ZnO nano-rod, which can be controlled by the reaction time of chemical process. Using conventional lift-off process, thin ZnO layer based transistor was fabricated by forming source/drain as well as gate electrode. More detailed ZnO-cellulose based transistor is discussed.

This paper consists of four parts: (1) The word-level representations of digital circuits which included (a) word-level arithmetic representation, (b) word-level sum-of-products representation, and (c) word-level Reed-Muller representation. (2) The three word-level nano ICs circuit designs. (3) The introduction of the vector Boolean derivative. (4) The fault detection in word-level digital circuits using the vector Boolean derivative. The formulas for deriving tests for detecting stuck-at-0 (s-a-0) and stuck-at-1(s-a-1) are given word-level digital circuit presented in in any of the three representations.

One of the promising emerging nanotechnologies is the molecular quantum-dot cellular automata (QCA). A considerable amount of attention has been given to the 2D 2-dot QCA circuit designs and simulations at the bit level by Hook and Lee. The purpose of this paper is two-fold: (1) to introduce a new 3D QCA lattice structure, formed by 2-dot QCA cells, and (2) to present a word-level QCA NanoIC design method using this 3D 2-dot QCA architecture, which uses a slice of the lattice to implement one bit of the word data. For example, for an 8-bit word, there will be 8 slices of 2-dot QCA lattice embedded in the NanoIC.

Current MEMS technology is perhaps reminiscent of the early semiconductor technology industry and the first computer systems. As technologies mature, a certain pattern of evolution typically ensues. This path, however, is fraught with challenges (e.g. efficient architectural exploration), which act as discontinuities in the advancement of a technology. Overcoming these obstacles requires innovations and, generally, the establishment of infrastructure. This paper proposes one vision for the future of MEMS technology, describing how the techniques employed in circuit and computing system design can be adapted to MEMS platform design to raise the level of abstraction and facilitate the creation of complex architectures.

The improvement of photovoltaic performance using micro- and nano-sized scale manufacturing is discussed in this paper. The development and design of small structures for photovoltaic applications are the most challenging aspects in enhancing light absorption efficiency. We demonstrate novel methods that allow for more efficient and successful manufacture and improvement of absorption properties using a nano-particle spraying method and generation of nano-islands by making a thin film and heat treatment of the thin film. In the nano-particle spraying method, a solution which can disperse particles uniformly is sought. The nano-particles are sprayed on a typical polycrystalline silicon solar cell with an air brush gun, and then an intense pulsed light is irradiated onto the surface to cause surface driven diffusion to the nano-particles and form the nano-islands. The whole process was performed under dry and ambient conditions. The secondary method, generation of nano-islands was achieved to improve the uniformity of scattered nanostructures. A deposition process, evaporation and sputtering under vacuum, is used to manufacture the metallic thin films with 10~30 nm thickness, and thermal treatment provides surface energy so that uniform nano-sized islands are generated. Both methods are verified through the improvement of light absorption and short circuit current density – an improvement of 14.8% and 17.1%, respectively. The simulated model verified the enhancement of light absorption under the range of the solar spectrum and the absorption profile into the photoactive layer.

The pixel array in a conventional image sensor performs worse than the human retina mainly in dynamic range and dark limit. These limitations may be overcome by introducing others, but we aim to overcome them without limitation given biological precedent and inspiration. Whereas conventional image sensors use linear analog pixels in a single-tier process, we design nonlinear digital pixels for multiple-tier processes. A wide dynamic range is easily achieved with nonlinearity, while image quality is ensured through digital signal processing and in-pixel analog-to-digital conversion. For low dark limit and high spatial resolution, we exploit the high fill factor and heterogeneous integration of emerging multiple-tier processes. Our progress is demonstrated with experimental results from three image sensor prototypes, which provide supporting evidence for the proposed approach.

The goal of this research is to develop a mechanically flexible and biocompatible neural probe for in-vivo monitoring of unit neural impulses in the brain. In this research we present an implantable flexible polyimide-based neural probe that can minimize mechanical impact into the brain. Our device also features a micro-drive device which allows us to vertically adjust the probe after surgical implantation. This presentation will present the design and fabrication methods of a flexible polyimide probe and a microdrive.

The detection of deep-lying small defects using eddy current non-destructive testing (NDT) involves high spatial resolution and AC field measurement capability. For this purpose multilayered Finemet^®/Copper/Finemet magneto-impedance microsensors were elaborated by microfabrication process. The films were deposited separately by sputtering using bi-layers lift-off method. A post-annealing step was achieved under magnetic field, which led to induce a transversal anisotropy in the magnetic films. A method based on double amplitude demodulation was proposed for the AC sensitivity characterization. A sensitivity of 2100 V/T/A has been measured and the sensors presented no hysteresis since a DC bias field larger than anisotropy field is applied. In addition, the sensors sensitivity remains constant up to 1 kHz.

Emerging applications for sensing and monitoring technology can no longer rely entirely on conventional sensor configurations, particularly where planar, rigid, and often fragile devices cannot meet demanding system sensing requirements. Direct-write Aerosol Jet (AJ) printing is establishing itself as an enabling technology for fabrication of sensors and circuit components on three dimensional, flexible surfaces for applications ranging from structural health monitoring to human factors and performance measurement. Examples will describe the versatility of AJ printing as a viable method for creating sensors that are conformally matched to the surface topology of a wide variety of substrates.

A previously synthesized silver nanoparticle based conductive silver ink was used in this work to print conductive electrodes on cellulose electro-active paper (EAPap) by using an inkjet printer. Then, Inkjet printed cellulose EAPap experienced a post-deposition heat treatment-sintering process to enhance electrical conductivity of printed electrodes by converting those printed patterns into continuous metallic state. The dependences of electrical bulk resistivity of printed electrodes on both sintering temperature and sintering time were checked. It was found that, higher sintering temperatures and longer sintering process result lower resistivity. In addition, the uniformity of the thicknesses of printed electrodes through transverse direction and the relationship between thickness and the number of printing also had been analyzed. Those printed electrodes also showed very good adhesion on cellulose EAPap.

Power consumption appears to be the biggest technical issue and performance bottleneck in the development of mobile wearable health monitoring systems. One promising approach for addressing this challenge is to harvest the body heat energy using flexible thermoelectric generators, and printing is a low-cost technique for large-scale fabrication of flexible circuits and systems. This paper discusses the development of thermoelectric inks that can be used in the fabrication of thermoelectric generators, which can be used as sustainable power sources for mobile wearable health monitoring systems. The operation mechanism of thermoelectric generators for body heat harvesting is discussed, followed by the requirements on the properties of thermoelectric inks for the fabrication of printable thermoelectric generators. To achieve high thermoelectric figure of merit, we synthesized nano-structured thermoelectric materials with high Seebeck coefficient and low thermal conductivity, and developed surface functionalized carbon nanotubes that can be used as conducting agents for improving the electrical conductivity of thermoelectric inks.

The general class of organic-inorganic hybrid nanocomposites materials is a fast growing area of research. The significant effort is focused on the ability to control the nanoscale structures via organic functional synthetic approaches with inorganic metal oxides. The properties of nanocomposites material depends on the properties of their individual components but also their morphological and interfacial characteristics. This rapidly expanding field is generating many exciting new materials with novel properties. Mainly, cellulose is considered as the richest renewable materials are presently among the most promising candidates for use in photonics due to their versatility, flexibility, light weight, low cost and ease of modification. Cellulose-metal oxide nanomaterials were developed the technologies to manipulate selfassembly and multifunctionallity, of new technologies to the point where industry can produce advanced and costcompetitive cellulose metal oxide hybrid materials. Therefore, the present study is focused on cellulose–functionalized - 4, 4’-(propane-2, 2’-diyl) diphenol-SiO₂/TiO₂ hybrid nano-composites materials by in-situ sol-gel process. The chemical and morphological properties of cellulose-functionalized SiO2/TiO2 materials via covalent crosslinking hybrids were characterized by FTIR, XRD, TGA, DSC, SEM, TEM and optical properties.

Integration of multiple chips and functions to the same radio module is a key issue when the size of a radio front-end is tried to minimize. VTT Technical Research Centre of Finland has developed both Low Temperature Co-fired Ceramics (LTCC) and Integrated Passive Devices (IPD) integration platforms for radio frequency (RF) integrated modules. Three dimensional (3D) integration technologies are enablers for realizing compact multi-chip modules with several different technologies in the same module. In addition to module level integration, both technologies are used for realizing high quality factor passive components.

Electromagnetic field interactions with the composites made up of polyaniline (PANI) and single wall carbon nanotube (SWCNT) are simulated using the discrete dipole approximation. Recent observations on polymer nano-composites explain the interface interactions between the PANI host and the carbon nanostructures. These types of composite have potential applications in organic solar cell, gas sensor, bio-sensor and electro-chromic devices. Various nanostructures of PANI is possible in the form of nanowires, nanodisks, nanofibers and nanotubes have been reported. In the present study, we considered two types of composite, one is the PANI wrapped CNT and the other is CNT immersed in PANI nanotube. We use Modified Thole’s parameters for calculating frequency dependent atomic polarizability of composites. Absorption spectra of the composites are studied by illuminating a wide range of electromagnetic energy spectrum. From the absorption spectra, we observe plasmon excitation in near-infrared region similar to that in SWCNTs reported recently. The interactions between the PANI and CNT in the composite, resulting electromagnetic absorptions are simulated.

Since carbon nanotubes (CNTs) have been discovered in 1991, worldwide scientific research reveals excellent properties. Most of the found properties refer to almost defect-free, single-walled carbon nanotubes (SWCNTs) with nano-scale dimensions. However, scientists try to incorporate CNTs into applications to transfer their features in order to push the specific performance. Typically the results are comparably lower than expected because of the varying quality of used CNTs. This paper presents results of research using CNTs as actuators. In contrast to published paper which analyzed architectures of entangled CNTs as active components, like papers or yarns, to measure their bulk-strain this paper focuses on scattered, highly aligned CNTs. This approach promises to clarify the effect of actuation, whether it is a quantum-mechanically, or rather an combined electrostatic volume-transfer effect. Two experimental set-ups are presented. The first experiment is carried out using highly aligned multi-walled CNTs (MWCNT-arrays). Their orientation is investigated intensively in comparison to other analyzed CNT-arrays. Furthermore their substrate consists of electrical conductive carbon. The CNT-array is optically analyzed along the longitudinal geometry of the vertically aligned MWCNTs. The interfaces of the set-up, which may influence the measurement, have been analyzed in order to avoid second-order effects like thermal swelling or chemical degradation. The results reveal comparable high deflections starting at an activation-voltage of ±1.75V. The ionic liquid is tested within a voltage-range of ±2V due to time-staple performance. The second presented results are found by using Raman-spectroscopy to analyze single SWCNTs. This paper presents the first results of the challenging test campaign to analyze single-walled nanotubes within an electrolyte during charging. A shifting of Raman-peaks according to the wavenumber can be directly attributed to a geometry-change. Thus, the two presented experiments uses aligned CNTs a driving actuation mechanism of single CNTs may be identified.

Spinel lithium manganese oxides (LiMn₂O₄) are favorable cathode materials for secondary lithium ion batteries mainly due to their low cost and excellent environmental suitability. Further, because of their high electrochemical potentials, spinel lithium manganese oxides are a type of promising cathode materials for high-power lithium ion batteries, such as the batteries for electric vehicles. However, the electrochemical properties of LiMn₂O₄ are strongly influenced by the synthesis methods and conditions. In this paper, the electrochemical properties of spinel LiMn₂O₄ synthesized by solid state reaction and sol-gel method were compared and analyzed. The effects of particle sizes on the electrochemical properties of spinel LiMn₂O₄ were discussed.

Cellulose films coated with ZnO nanoparticles constitute an important material for practical applications ranging from the film paint industry to the technologically appealing area of optoelectronic paper. ZnO-cellulose hybrid nanocomposite was fabricated by growing ZnO on regenerated cellulose directly. This organic-inorganic nanocomposite exhibits excellent piezoelectric behavior. This paper reports electrical and electromechanical behaviors of the ZnOcellulose hybrid nanocomposite. The fabrication process is briefly introduced, and induced voltage, remnant polarization as well as piezoelectricity between cellulose substrate and ZnO-layers are investigated. Also its charging and discharging behaviors are studied, and its application possibility for super capacitor, paper battery, field effect transistor will be discussed.

Iron oxide nanoparticles, including magnetite, maghemite and hematite, are promising electrode active materials for lithium ion batteries due to their low cost, high capacity and environmental friendliness. Though the electrochemical properties of each kind of iron oxide nanoparticles have been intensively studied, systematic comparison of the three kinds of iron oxides is hardly reported. This paper reports the study and comparison of the electrochemical properties of magnetite, maghemite and hematite nanoparticles with the same shape and size. In this work, hematite and maghemite nanoparticles were obtained from commercial magnetite nanoparticles by thermal treatments at different conditions. Their crystalline structures were characterized by X-ray diffraction (XRD), their magnetic properties were measured by a vibration sample magnetometer (VSM), and their particle morphologies were analyzed by scanning electron microscopy (SEM). Composite electrodes were made from iron oxide nanoparticles with carbon black as the conducting material and PVDF as the binding material (iron oxide : carbon black : PVDF = 70 : 15 : 15). Prototype lithium ion batteries (CR2032 button cells) were assembled with iron oxide composite electrodes as cathodes, metal lithium as anodes, and Celgard 2400 porous membrane as separators. The impedance and discharge-charge behaviors were characterized by a Solartron electrochemical workstation and an Arbin battery tester, respectively. It was found that at the same shape and size, hematite nanoparticles has higher specific discharge and charge capacities than magnetite and maghemite nanoparticles.

Ultrasonic-Atomic Force Microscopy (U-AFM) was applied to determine the feasibility of visualizing interior features in an ultra-thin film system. As the amplitude and phase of the cantilever resonance frequency changes with local contact stiffness, U-AFM can obtain both surface and subsurface topographic and elastic images. Specimens with nanostructured silicon dioxide (SiO₂) patterns deposited on silicon (111) surfaces were fabricated and covered with polymethyl methacrylate (PMMA) films with thicknesses of 800 nm and 1400 nm, respectively. While subsurface features were barely distinguishable beneath the 1400 nm film, 100 nm SiO₂ features were clearly visualized for PMMA film thicknesses below and up to 800 nm. This research demonstrates the potential of U-AFM as a powerful technique for visualizing nanoscale subsurface features in microelectronic devices.

This paper reports a flexible and disposable ZnO blended cellulose hybrid nanocomposites (Cellulose/ZnO hybrid) film and its feasibility for a resistive glucose biosensor. Cellulose/ZnO hybrid film was fabricated by simply blending ZnO nanoparticles with cellulose solution prepared by dissolving cotton pulp with LiCl/DMAc solvent. Cellulose/ZnO hybrid film was cured in isopropyl alcohol and water mixture and free standing film was obtained. For biosensor application, the enzyme glucose oxidase was immobilized into the Cellulose/ZnO hybrid film by physical adsorption method. The enzyme activity of the glucose biosensor increases as the ZnO weight ratio increases linearly in the range of 1-12mM.

Solar cells can be produced using thin film based photovoltaic materials; these are highly efficient with respect to their optical properties and manufacturing cost. The prospective thin film solar cells are composed of Copper, Zinc, Tin, and Sulfide, or ‘CZTS’, this contains chemicals, which are both earth-abundant and non-toxic. The all-solution based process is investigated which is on a single-step electro-chemistry deposition that provides all constituents from the same electrolyte. This investigation was successful in our research group with a high degree of success and a photo-thermal energy driven sintering process that forms a CZTS material from the as-deposited chemicals was added. This enables the as-deposited chemicals to be covalently bonded and crystallized without using a costly vacuum process. In post-heat treatment, a homemade intense pulsed lighting (IPL) system was utilized for rapid thermal annealing. The successful deposition of the CZTS thin film was then evaluated and analyzed using cyclic voltammetry (CV), SEM/EDAX, and XRD. It has been concluded that photovoltaic thin film fabrication is truly comparable to the conventional deposition and annealing methods in terms of photovoltaic efficiency and cost-effectiveness.

Gels have unique properties such as low frictional properties, permeability and biocompatibility due to their high water content. When the gels are developed as industrial materials, we need to establish a method of quantitative analysis derived from the internal structure and the mechanical properties of these gels. However, the static inhomogeneities in gels prevent us to observe the structure of gels by scattering method. To solve this problem, we have developed scanning microscopic light scattering (SMILS) originally. In this study, firstly, the internal structure of the dry-synthesis gels are precisely examined experimentally by the scattering microscopic light scattering and theoretically by the tensile test. By comparing the two quantities, the dense network structure makes the mechanical properties of gels smaller than theoretical estimation. Secondary, we show the new system named Visual-SMILS that can provide the 2-dimentional data of the distribution. Based on our findings, the strength of the gels can be controlled and expected. We believe the Visual-SMILS system will promote research significantly in the field of gels.

In the present study, we characterize internal structure of shape memory gel with Scanning Microscopic Light Scattering (SMILS), which is typically a dynamic light scattering system developed in our laboratory. It is specialized for analyzing the microscopic structure of gels having scanning as well as multi-angle facility. Transparent shape memory gel is prepared by solvent free technique using two monomers. The ratio of N,N-dimethyl acrylamide (DMAAm) and Stearyl acrylate (SA) is 3:1 in molar ratio. The mesh size of internal network structure of shape memory gel is determined by the SMILS and it is found in several nm in size. The diffusion coefficient is calculated and the critical temperature is observed where gel is changed its phase.

The molecular mechanism has been employed to model the structure-property relationships of auxetic material with tetrahedral framework at the atomistic level. The germania α–quartz subject uniaxial stress loading in z direction will be investigated. The strain-dependent structure and mechanical properties will be predicted from the force field based simulations, including the transformation from positive-to-negative Poisson’s ratio behaviour and vice versa.

With advantages of ultra-compact size, high resolution, and easy integration, nano-scaled force sensors based on photonic crystal are widely used in microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS). The performances of these nano-scaled force sensors are mainly determined by the shape nanocavity. The principle of the sensor is that the output wavelength of the force sensor using photonic crystal varies as a function of force and pressure. In this work, a novel three dimensional nano-scaled force sensor based on silicon photonic crystal, in which a nanocavity is embedded in an S-shaped elastic body, is provided and studied numerically. The advantage of this force sensor is that it can be used in the NEMS to measure the component force in the X direction, Y direction and Z direction, simultaneously. The relationship between the force and the output wavelength is determined using finite element method (FEM) and finite difference time-domain method (FDTD).

Indentation tests have been used to measuring the strength and hardness of materials. Moreover, micro and nanoindentation have become major tools for investigating the micromechanical properties of small scale volumes. However, it is well-known that the micro and nanoindentation hardness of materials shows the strong size effect. But the classical continuum plasticity can’t predict these size effects in micro/nano scale, since the constitutive equation of the classical mechanics doesn’t include the internal length as a parameter for the deformation. In this paper, modified strain gradient theory is proposed based on the nonhomogeneity of polycrystalline metallic materials. When the grains of crystalline metals deform, overlaps and voids appear at the grain boundary. These overlaps and voids can be corrected by the GNDs. By taking into account the nonhomogeneity of polycrystalline materials, the density of the GNDs due to the deformation is calculated. Consideration of the GNDs on the grain boundary gives a relationship between the size effect and the hardness. This relationship can explain the indentation size effects in micro/nano scale. Using the proposed model, analysis of the effect of indent size and grain size under the nanoindentation test of polycrystalline materials is carried out.

Epilepsy affects 2.5 million people in the USA, 15% of which cannot be treated with traditional methods. Effective treatments require reliable prediction of seizures to increase their effectiveness and quality-of-life. Phase synchronization phenomenon of two distant neuron populations for a short period of time just prior to a seizure episode is utilized for such prediction. This paper presents a hardware efficient prediction algorithm using phase-difference (PD) method instead of the commonly used phase-locking statistics (PLS). The dataset has been collected from publicly available “CHB-MIT Scalp EEG Database” that consists of scalp EEG recordings from 10 pediatric subjects with intractable seizures. The seizure channel is selected based on the maximum value of the standard deviation during seizure, while the reference channel has the minimum value of the standard deviation. Data from these two channels is conditioned with a band-pass (f_lc = 10Hz, f_hc = 12.5Hz) 6^th order Chebyshev Type II filter or a FIR filter. The analytical signals are derived using Hilbert Transform to allow phase extraction. PLS and PD are calculated from the mean of the phase-differences using an overlapping sliding-window technique. PD method demonstrates the same characteristics as PLS, while achieving 2.35 times faster computation rate in MATLAB than PLS. With 51 seizure episodes, prediction latency was between 51 seconds to 188 minutes with sensitivity of 88.2%. PD yields to lower hardware requirement and reduces computational complexity.

In order to study and improve atmospheric and air pollution monitoring sensor, a new mathematical model of random signals is established based on measuring process of light scattering signals analyzed by laser particle counter which combines the high speed data acquisition card PCI-9812 and optical particles counting sensor. The measured random signals can be divided into stability constant part and random variation part. The performance of the instrument is improved by both this model and analytical methods. Statistical distributions of the amplitude of the standard particles with different diameters are studied by the original experiment and improved one. The resolving power of particle size could attain more than 90%. The results reveal statistical distributions match well with lognormal distribution with a natural number as an independent variable. The lognormal distribution plays an important role in describing the random fluctuation characteristics of random process in both theories and experiments. Furthermore, both normal and lognormal distribution fitting are applied in analyzing the experimental results and testified by chi-square distribution fit test and correlation coefficient for comparison.

This PDF file contains the front matter associated with SPIE Proceedings Volume 8691, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.