Electroactive polymer based microfluidic pump

A planar, valveless, microfluidic pump using electrostrictive poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] based polymer as the actuator material is presented. P(VDF-TrFE) thick films having a large electrostrictive strain ∼5–7% and high elastic energy density of 1 J/cm³ have been used in a unimorph diaphragm actuator configuration. The microfluidic pump was realized by integrating a nozzle/diffuser type fluidic mechanical-diode structure with the polymer microactuator. The P(VDF-TrFE) unimorph diaphragm actuator, 80 μm thick and 2.2 mm × 2.2 mm in lateral dimensions, showed an actuation deflection of 80 μm for an applied electric field of 90 MV/m. The microfluidic pump could pump methanol at a flow rate of 25 μl/min at 63 Hz with a backpressure of 350 Pa. The flow rate of this pump could be easily controlled by external electrical field. Two different sizes of nozzle/diffuser elements were studied and the pumping efficiency of these structures is 11 and 16%, respectively.     

Development of wireless compressive/relaxation-stress measurement system integrated with pressure-sensitive carbon black-filled silicone rubber-based sensors

In order to detect the installation compressive stress and monitor the stress relaxation between two bending surfaces on a defensive furnishment, a wireless compressive-stress/relaxation-stress measurement system based on pressure-sensitive sensors is developed. The flexible pressure-sensitive stress sensor array is fabricated by using carbon black-filled silicone rubber-based composite. The wireless stress measurement system integrated with this sensor array is tested with compressive stress in the range from 0 MPa to 3 MPa for performance evaluation. Experimental results indicate that the fractional change in electrical resistance of the pressure-sensitive stress sensor changes linearly and reversibly with the compressive stress, and its fractional change goes up to 355% under uniaxial compression; the change rate of the electrical resistance can track the relaxation stress and give out a credible measurement in the process of stress relaxation. The relationship between input (compressive stress) and output (the fractional change in electrical resistance) of the pressure-sensitive sensor is ΔR/R₀ = σ × 1.2 MPa^?1. The wireless compressive stress measurement system can be used to achieve sensitivity of 1.33 V/MPa to the stress at stress resolution of 920.3 Pa. The newly developed wireless stress measurement system integrated with pressure-sensitive carbon black-filled silicone rubber-based sensors has advantages such as high sensitivity to stress, high stress resolution, simple circuit and low energy consumption.     

A DFT study on the central-ring doped HBC nanographenes

Nanographenes (NGs) are a segment of graphene whose dangling bonds are saturated with hydrogen atoms, introducing different properties and promising applications. Here we investigate the electronic, thermodynamic, optical, and structural properties of four C₃₆X₃Y₃H₁₈ NGs (X = B, and Al; and Y = N, and P) based on the density functional theory calculations. It was mainly found that 1) BN-NG is planar molecule and the others are buckybowl-shaped ones, 2) The bowl-to-bowl inversion Gibbs free energies (ΔG^#) of buckybowl shaped NGs are very huge and the rate constant is very small, hindering the inversion, 3) The relative energetic stability order based on the standard enthalpy of formation (ΔH_f^°) is as BN > AlN > BP > AlP, which the BN, and AlN doped NGs are stable at room temperature but the BP and AlP doped ones are instable, 4) The electrical conductivity order of magnitude is inverse of that of stability, 5) An exciton binding energy is predicted in the range of 0.57–0.75 eV for the NGs which corresponds to Frenkel exciton type, 6) the NGs are not soluble in organic solvent in agreement with the experimental results and is partially soluble in water solvent with Gibbs free energy of solvation (ΔG_solv) in the range of −6.1 to −10.1 kcal/mol.     

Potentiometric study of quinohemoprotein alcohol dehydrogenase immobilized on the carbon rod electrode

Enzymes, which exhibit redox properties and are able to directly exchange electrons with conducting materials, are currently of special interest in the fields of biosensorics and bioelectronics. The detection of new electronic properties makes them even more attractive for these growing fields. Quinohemoprotein alcohol dehydrogenase (QH-ADH) from Gluconobacter sp. 33 was demonstrated as ‘nano-sized electrical power generator’ able to separate the electrical charges and generate a measurable electrical potential. This phenomenon was investigated potentiometrically in electrochemical system where QH-ADH was applied as the catalyst oxidizing ethanol thereby converting the energy of this chemical reaction to an electrical potential. A basic immobilization technique based on cross-linking with glutaraldehyde was applied for the immobilization of QH-ADH onto a carbon rod. The maximal open circuit potential generated by QH-ADH immobilized on carbon rod electrode was −115 mV versus an inactivated QH-ADH-modified electrode (Inactiv-ADH/carbon). If 10 mM of redox mediator K₃[Fe(CN)₆] was added to the solution the potential rose to −190 mV versus Inactiv-ADH/carbon. The influence of concentration of Na acetate buffer, pH 6.0, on registered potential was approximately at the same level as the influence of KCl concentration (influence of ionic strength). This result implies that local pH changes do not play a significant role in the development of QH-ADH-modified carbon electrode potential. The potentiometric signal was more stable than amperometric signal based on the same QH-ADH-modified carbon electrode. The ability to directly generate electric potential opens new opportunities for the application of QH-ADH and other direct electron transfer exhibiting enzymes in the design of new potentiometric sensors, biofuel cells and self-powering bioelectronic devices.     

Advanced control with parameter estimation of batch transesterification reactor

The objective of this work is to enhance the economic performance of a batch transesterification reactor producing biodiesel by implementing advanced, model based control strategies. To achieve this goal, a dynamic model of the batch reactor system is first developed by considering reaction kinetics, mass balances and heat balances. The possible plant-model mismatch due to inaccurate or uncertain model parameter values can adversely affect model based control strategies. Therefore, an evolutionary algorithm to estimate the uncertain parameters is proposed. It is shown that the system is not observable with the available measurements, and hence a closed loop model predictive control cannot be implemented on a real system. Therefore, the productivity of the reactor is increased by first solving an open-loop optimal control problem. The objective function for this purpose optimizes the concentration of biodiesel, the batch time and the heating and cooling rates to the reactor. Subsequently, a closed-loop nonlinear model predictive control strategy is presented in order to take disturbances and model uncertainties into account. The controller, designed with a reduced model, tracks an offline determined set-point reactor temperature trajectory by manipulating the heating and cooling mass flows to the reactor. Several operational scenarios are simulated and the results are discussed in view of a real application. With the proposed optimization and control strategy and no parameter mismatch, a revenue of 2.76 $ min⁻¹ can be achieved from the batch reactor. Even with a minor parameter mismatch, the revenue is still 2.01 $ min⁻¹. While these values are comparable to those reported in the literature, this work also accounts for the cost of energy. Moreover, this approach results in a control strategy that can be implemented on a real system with limited online measurements.     

A magnetoelectric energy harvester and management circuit for wireless sensor network

This paper presents an electromagnetic energy harvesting scheme by using a composite magnetoelectric (ME) transducer and a power management circuit. In the transducer, the vibrating wave induced from the magnetostrictive Terfenol-D plate in dynamic magnetic field is converged by using an ultrasonic horn. Consequently more vibrating energy can be converted into electricity by the piezoelectric element. A switching capacitor network for storing electricity is developed. The output of the transducer charges the storage capacitors in parallel until the voltage across the capacitors arrives at the threshold, and then the capacitors are automatically switched to being in series. More capacitors can be employed in the capacitor network to further raise the output voltage in discharging. For the weak magnetic field environment, an active magnetic generator and a magnetic coil antenna under ground are used for producing an ac magnetic field of 0.2–1 Oe at a distance of 25–50 m. In combination with the supply management circuit, the electromagnetic energy harvester with a rather weak power output (about 20 μW) under an ac magnetic field of 1 Oe can supply power for wireless sensor nodes with power consumption of 75 mW at a duration of 620 ms.     

Facile synthesis of lanthanide vanadates and their luminescent properties

GdVO₄:Eu³⁺, Bi³⁺ with tetragonal phase has been successfully synthesized by employing efficient irradiations. The assembly of composites with fine grains based on acoustic energy and microwave radiation requires low temperature (90 °C) and short reaction time (60 min). All the compounds exhibited red emissions and they can be sensitized through the doped Bi³⁺ ions. The dependence of pH changes and doping concentration on the fluorescence features has been discussed. The photoluminescence measurements show that the optical properties achieved the best results at pH = 9 for GdVO₄:Eu³⁺(5 mol%), Bi³⁺(1 mol%) or pH = 7 for GdVO₄:Eu³⁺.     

The possibility of using C20 fullerene and graphene as semiconductor segments for detection,and destruction of cyanogen-chloride chemical agent

Detection of hazardous chemical species by changing the electrical conductivity of a semiconductor matter is a proposed and applied way for decreasing their subsequent unpleasant effects. Recently, many examples of using inorganic or organic materials, polymeric, and also nano-sized species as sensors were reported in which, in some cases, those matters were strongly affective and suitable.In this project, we have made an assessment on whether the graphene segment or C₂₀ fullerene, able to sense the existence of cyanogen chloride NCCl? In order to gain trustable results, the possible reaction pathways along with the adsorption kinetics were investigated. Moreover, the electronic density of states DOS showed that C₂₀ fullerene senses the existence of cyanogen chloride agent with a clearer signal (ΔE_g = 0.0110 eV) compared to the graphene segment (ΔE_g = 0.0001 eV). Also the adsorption energy calculations showed that cyanogen chloride could be adsorbed by the fullerene in a multi-step process (E_ads1 = −0.852 kcal mol⁻¹; E_ads2 = −0.446 kcal mol⁻¹; E_ads3 = −2.330 kcal mol⁻¹).     

The comparison of two domain repartitioning methods used for parallel discrete element computations of the hopper discharge

The paper presents an application of two domain repartitioning methods to solving hopper discharge problem simulated by the discrete element method. Quantitative comparison of parallel speed-up obtained by using the multilevel k-way graph partitioning method and the recursive coordinate bisection method is presented. The detailed investigation of load balance, interprocessor communication and repartitioning is performed. Speed-up of the parallel computations based on the dynamic domain decomposition is investigated by a series of benchmark tests simulating the granular visco-elastic frictional media in hoppers containing 0.3 × 10⁶ and 5.1 × 10⁶ spherical particles. A soft-particle approach is adopted, when the simulation is performed by small time increments and the contact forces between the particles are calculated using the contact law. The parallel efficiency of 0.87 was achieved on 2048 cores, modelling the hopper filled with 5.1 × 10⁶ particles.     

Fiber optics sensor for sub-nanometric displacement and wide bandwidth systems

In this paper, we report fiber optics sensor with sub-nanometric resolution and wide bandwidth. It relies on an increase of the reception fibers number and on low-noise electronics. Moreover, a reference channel has been implemented using a semi-reflective plate to eliminate the source fluctuations and the fiber sensor was isolated to limit external influence of temperature and pressure. Thus we achieve both a sub-nanometric resolution on a 400 ms integration time and a long-term drift as low as 40 nm h^?1. The setup has been also adapted to high speed applications by increasing the bandwidth up to 38 kHz. It can display a 28 nm peak-to-peak limit of resolution on an aluminized piezoactuator. It has been successfully used to test the resonance frequency of a vibrating plate actuated by two high-frequency prototypes of piezoactuators. These improvements lead to low cost fibers optic sensors interesting for non-contact displacement measurements with high sensitivity.     

Theoretical Study on Free Fatty Acid Elimination Mechanism for Waste Cooking Oils to Biodiesel over Acid Catalyst

A theoretical investigation on the esterification mechanism of free fatty acid (FFA) in waste cooking oils (WCOs) has been carried out using DMol³ module based on the density functional theory (DFT). Three potential pathways of FFA esterification reaction are designed to achieve the formation of fatty acid methyl ester (FAME), and calculated results show that the energy barrier can be efficiently reduced from 88.597 kcal/mol to 15.318 kcal/mol by acid catalyst. The molar enthalpy changes (Δ_rH_m°) of designed pathways are negative, indicating that FFA esterification reaction is an exothermic process. The obtained favorable energy pathway is: H⁺ firstly activates FFA, then the intermediate combines with methanol to form a tetrahedral structure, and finally, producing FAME after removing a water molecule. The rate-determining step is the combination of the activated FFA with methanol, and the activation energy is about 11.513 kcal/mol at 298.15 K. Our results should provide basic and reliable theoretical data for further understanding the elimination mechanism of FFA over acid catalyst in the conversion of WCOs to biodiesel products.     

Monitoring land degradation risk using ASTER data: The non-evaporative fraction as an indicator of ecosystem function

There is a need to develop operational land degradation indicators for large regions to prevent losses of biological and economic productivity. Disturbance events press ecosystems beyond resilience and modify the associated hydrological and surface energy balance. Therefore, new indicators for water-limited ecosystems can be based on the partition of the surface energy into latent (λE) and sensible heat flux (H).In this study, a new methodology for monitoring land degradation risk for regional scale application is evaluated in a semiarid area of SE Spain. Input data include ASTER surface temperature and reflectance products, and other ancillary data. The methodology employs two land degradation indicators, one related to ecosystem water use derived from the non-evaporative fraction (NEF = H / (λE + H)), and another related to vegetation greenness derived from the NDVI. The surface energy modeling approach used to estimate the NEF showed errors within the range of similar studies (R² = 0.88; RMSE = 0.18 (22%)).To create quantitative indicators suitable for regional analysis, the NEF and NDVI were standardized between two possible extremes of ecosystem status: extremely disturbed and undisturbed in each climatic region to define the NEFS (NEF Standardized) and NDVIS (NDVI Standardized). The procedure was successful, as it statistically identified ecosystem status extremes for both indicators without supervision. Evaluation of the indicators at disturbed and undisturbed (control) sites, and intermediate surface variables such as albedo or surface temperature, provided insights on the main surface energy status controls following disturbance events. These results suggest that ecosystem functional indicators, such as the NEFS, can provide information related to the surface water deficit, including the role of soil properties.     

Stable white light emission from an externally modified organic light-emitting device

A blue organic light-emitting device, based on an iridium phosphorescent dopant in a polyvinylcarbazole host, has been modified by the addition of an external CaS:Eu inorganic phosphor layer. By incorporating a surfactant in the phosphor mixture, a uniform coating could be achieved by drop-casting. The resulting hybrid device exhibited white light emission, with Commission Internationale de l’Eclairage, CIE (x, y) coordinates of x = 0.32, y = 0.35. No significant change in these coordinates was observed for current densities in the range 25–510 A m^?2. The maximum power efficiencies of the white device was 2.3 lm W^?1 at a brightness of 254 cd m^?2.     

Remote sensing of canopy light use efficiency in temperate and boreal forests of North America using MODIS imagery

Light use efficiency (LUE) is an important variable characterizing plant eco-physiological functions and refers to the efficiency at which absorbed solar radiation is converted into photosynthates. The estimation of LUE at regional to global scales would be a significant advantage for global carbon cycle research. Traditional methods for canopy level LUE determination require meteorological inputs which cannot be easily obtained by remote sensing. Here we propose a new algorithm that incorporates the enhanced vegetation index (EVI) and a modified form of land surface temperature (T_m) for the estimation of monthly forest LUE based on Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. Results demonstrate that a model based on EVI × T_m parameterized from ten forest sites can provide reasonable estimates of monthly LUE for temperate and boreal forest ecosystems in North America with an R² of 0.51 (p < 0.001) for the overall dataset. The regression coefficients (a, b) of the LUE–EVI × T_m correlation for these ten sites have been found to be closely correlated with the average EVI (EVI_ave, R² = 0.68, p = 0.003) and the minimum land surface temperature (LST_min, R² = 0.81, p = 0.009), providing a possible approach for model calibration. The calibrated model shows comparably good estimates of LUE for another ten independent forest ecosystems with an overall root mean square error (RMSE) of 0.055 g C per mol photosynthetically active radiation. These results are especially important for the evergreen species due to their limited variability in canopy greenness. The usefulness of this new LUE algorithm is further validated for the estimation of gross primary production (GPP) at these sites with an RMSE of 37.6 g C m^? 2 month^? 1 for all observations, which reflects a 28% improvement over the standard MODIS GPP products. These analyses should be helpful in the further development of ecosystem remote sensing methods and improving our understanding of the responses of various ecosystems to climate change.     

Software sensors are a real alternative to true sensors

At the Ejby Mølle WWTP in Odense Denmark a software sensor predicts the ammonium and nitrite + nitrate concentration in real-time based on ammonium and redox potential measurements. The predicted ammonium concentration is used to control the length of the nitrification phase in a Biodenipho^® activated sludge unit because the software sensor has a shorter response time and a better up-time than the ammonium meter. The software sensor simplifies meter service and can reduce maintenance costs. The computed nitrite + nitrate concentration is an added benefit of the software sensor. On 4 different days, series of grab samples of the mixed liquor were collected in the aeration tanks. The average difference between the ammonium concentrations in the grab samples and the predicted ammonium concentration was 0.2 mgN L^?1 and the average difference between the predicted and the measured nitrite + nitrate concentration was 0.3 mgN L^?1. The agreement between the predicted and the measured ammonium concentration in the grab samples was better than the agreement between the ammonium meter and the grab samples. This was due to the shorter response time of the software sensor compared with the ammonium meter.     

Fabrication and frequency response of dual-element ultrasonic transducer using PZT-5A thick film

Ultrasonic transducers based on PZT-5A thick films deposited onto polycrystalline Al₂O₃ substrates using screen-printing were successfully fabricated. Considering the relatively high sintering temperature of PZT-5A thick films and better impedance matching characteristics with PZT-5A, polished polycrystalline Al₂O₃ were used as substrates. For electrodes, high quality platinum (Pt) was deposited by a thin film process, because the surface state of electrodes greatly affects the quality of piezoelectric films. Applying Pt/PZT-5A/Pt/Al₂O₃ structures, dual-element ultrasonic transducers were assembled. The assembled transducers included a wear plate (normally alumina with 40.21 × 10⁶ kg/m² s of impedance), backing (tungsten carbide-epoxy), electrical matching, an epoxy glue layer, and a housing. The optimum measurement ranges of 5 and 10 MHz ultrasonic transducers were 2.51–300.2 and 2.50–250.1 mm, respectively. From the time and frequency response measurements of the assembled 10 MHz DEUTs, the value of −20 dB level waveform duration and the −6 dB bandwidth was 481.8 ns and 34.4%, respectively. Also, the measurement accuracies of both 5 and 10 MHz DEUTs assembled in this study were below 0.1 and 0.4%, respectively.     

Application of the independent molecule model to elucidate the dynamics of structure I methane hydrate: A second report

Two model systems of methane hydrate are constructed. One has a small cage surrounded by 12 large cages. The other has a large cage surrounded by four small cages and ten large cages. Three different H-bonding network patterns between waters are formed, and three random configurations of methane in each cage are chosen. A new method called the surface water fixed model is presented in which the energy minimum conformations for both model systems are preserved close to the X-ray crystallized structure. With normal mode analysis, we calculated frequencies of 2916.6 cm⁻¹ for a small cage at a centre, 2915.9 cm⁻¹ not at a centre, and 2911.7 cm⁻¹ for a large cage at a centre, and 2911.3 cm⁻¹ not at a centre. These frequencies are in moderate agreement with the corresponding Raman spectra, though not adequate. With our new method, however, it should be possible to improve agreement with the Raman spectra, if a model system vastly larger than the present model systems were constructed.     

Integrated chip-size antennas for wireless microsystems: Fabrication and design considerations

This paper reports on fabrication and design considerations of an integrated folded shorted-patch chip-size antenna for applications in short-range wireless microsystems and operating inside the 5–6 GHz ISM band. Antenna fabrication is based on wafer-level chip-scale packaging (WLCSP) techniques and consists of two adhesively bonded glass wafers with patterned metallization and through-wafer electrical interconnects. Via formation in glass substrates is identified as the key fabrication step. Various options for via formation are compared and from these, a 193 nm excimer laser ablation is selected for fabrication of the antenna demonstrator. The fabricated antenna has dimensions of 4 mm × 4 mm × 1 mm, measured operating frequency of 5.05 GHz with a bandwidth of ∼200 MHz at the return loss of −10 dB and a simulated radiation efficiency of 60% were achieved.     

High speed detection of potato and clod using an acoustic based intelligent system

Discriminating between potato tubers and clods is the first step in developing an automatic separation system on potato harvesters. In this study, an acoustic-based intelligent system was developed for high speed discriminating between potato tubers and soil clods. About 500 kg mixture of potato tubers and clods were loaded on a belt conveyer and were impacted against a steel plate at four different velocities. The resulting acoustic signals were recorded, processed and potential features were extracted from the analysis of sound signals in both time and frequency domains. A multilayer perceptron neural network with a back propagation algorithm was used for pattern recognition. Altogether, 17 potential discriminating features were selected and fed as input vectors to the artificial neural network models. Optimal network was selected based on mean square error, correct detection rate and correlation coefficient. At the belt velocity of 1 m s^?1, detection accuracy of the presented system was about 97.3% and 97.6% for potatoes and clods, respectively. Increasing the belt velocity resulted in the reduction of detection accuracy and increase in the number of miss classified samples. By using this system, it is expected that a potato harvester may operate at a capacity of 20 ton hr^?1 with the accuracy of about 97%.