Spherically expanding flames propagating at constant pressure were employed to determine the laminar burning velocity and flammability characteristics of biogas-air mixtures in premixed combustion to uncover the funda...
Spherically expanding flames propagating at constant pressure were employed to determine the laminar burning velocity and flammability characteristics of biogas-air mixtures in premixed combustion to uncover the fundamental flame propagation characteristics of a new alternative and renewable fuel. The results are compared with those from a methane-air flame. Biogas is a sustainable and renewable fuel that is produced in digestion facilities. The composition of biogas discussed in this paper consists of 66.4% methane, 30.6% carbon dioxide and 3% nitrogen. Burning velocity was measured at various equivalence ratios () using a photographic technique in a high pressure fan-stirred bomb, the initial condition being at room temperature and atmospheric pressure. The flame for methane-air mixtures propagates from =0.6 till =1.3. The flame at ≥ 1.4 does not propagate because the combustion reaction is quenched by the larger mass of fuel. At ≤0.5, it does not propagate as well since the heat of reaction is insufficient to burn the mixtures. The flame for biogas–air mixtures propagates in a narrower range, that is from =0.6 to =1.2. Different from the methane flame, the biogas flame does not propagate at ≥1.3 because the heat absorbed by inhibitors strengthens the quenching effect by the larger mass of fuel. As in the methane flame, the biogas flame at ≤0.5 does not propagate. This shows that the effect of inhibitors in extremely lean mixtures is small. Compared to a methane-air mixture, the flammability characteristic (flammable region) of biogas becomes narrower in the presence of inhibitors (carbon dioxide and nitrogen) and the presence of inhibitors causes a reduction in the laminar burning velocity. The inhibitor gases work more effectively at rich mixtures because the rich biogas-air mixtures have a higher fraction of carbon dioxide and nitrogen components compared to the lean biogas-air mixtures.
Ultrafine elongated grain (UFEG) structures with strong 〈110〉// rolling direction (RD) fiber deformation texture were produced by warm caliber-rolling at 773 K, namely tempforming in the 1200 MPa-class medium-carbon l...
详细信息
As the rapid growth of smart phone technology, people have a lot of digital image information such as digital photos or videos. Both data hiding and data compression are very important technologies in image processing...
详细信息
As the rapid growth of smart phone technology, people have a lot of digital image information such as digital photos or videos. Both data hiding and data compression are very important technologies in image processing field. On the overview, it seems that there is no relationship between data hiding and data compression because data hiding mechanisms focus on information security and data compression mechanisms emphasize the compression ratio. However, the more secret data is embedded, the more capacity the stego image increases. Actually, they are closely related. Until now, there are many literatures to discuss the secret data how to be embedded into the media image and keeps the original capacity as soon as possible. In this paper, a reversible data hiding scheme based on EMD data hiding and JPEG (Joint Picture Experts Group) compression technology will be proposed. According to experimental results, the authors can prove that our proposed scheme maintains high embedding capacity, security and good compression ratio.
There has been a considerable increase in the population proportion of senior people among global population. Fall often happens among these senior people, which is also the leading cause of their death. A real-time f...
详细信息
There has been a considerable increase in the population proportion of senior people among global population. Fall often happens among these senior people, which is also the leading cause of their death. A real-time fall detection system may help us to detect fall events among elderly people in time and reduce the overall casualty rate. This paper proposed a home-based, real-time fall detection system that not only can distinguish up to 4 different kinds of fall events (forward, backward, rightward and leftward), but is also portable, low-cost and with high accuracy rate. The system includes a real-time fall detection band, a home server, and GSM instant messaging function which can transfer fall alert, send emergency help messages.
Measuring the blood pressure as accurately as possible can save a lot of human lives. Hence, it is very important to find an optimal method to determine the systolic and diastolic pressures out of the measured oscillo...
详细信息
Measuring the blood pressure as accurately as possible can save a lot of human lives. Hence, it is very important to find an optimal method to determine the systolic and diastolic pressures out of the measured oscillometric blood pressure waveform. Recently, studies have been showing that, by working in the frequency domain, outperforming results could be obtained. Using the digital Taylor-Fourier transform (DTFT) even allows separating the breathing and cardiac activity that is present in the oscillometric waveform. Furthermore, an estimate of the frequency fluctuation can easily be obtained. In this paper, we will investigate whether or not a Kalman filtering implementation can provide better results than the DTFT analysis. In theory both approaches should be equally performing. Both techniques will be compared on measured oscillometric waveforms. Even if the alternating Kalman filter does not excel the DTFT algorithm in interharmonic rejection, it offers interesting signal decomposition alternatives.
Silicon microcantilevers were coated by pulsed laser deposition with vanadium dioxide (VO2) (monoclinic M1 phase) and V 1-xCrxO2 with x near 0.024 (monoclinic M 2 phase), and their mechanical characteristics were stud...
详细信息
Silicon microcantilevers were coated by pulsed laser deposition with vanadium dioxide (VO2) (monoclinic M1 phase) and V 1-xCrxO2 with x near 0.024 (monoclinic M 2 phase), and their mechanical characteristics were studied as a function of temperature through the films' insulator-to-metal transition (IMT). The undoped VO2 films grew with (011)M1 planes parallel to the substrate, while Cr-doped VO2 films grew oriented with (201)M2 and (2 01)M2 planes parallel to the substrate. In both cases, the films transformed reversibly through the IMT to the tetragonal (rutile, R) phase, with film (110)R planes oriented parallel to the substrate. The fundamental resonant frequencies of the cantilevers were measured as the temperature was cycled from ambient temperature, through the IMT, and up to 100 °C. Very high resonant frequency changes were observed through the transition for both types of samples, with increases during heating of over 11 and over 15 for the cantilevers coated with pure and Cr-doped VO2, respectively. From the resonant frequencies measured at room temperature for the bare and coated cantilevers in each case, the effective Young's moduli of the films were determined. The values obtained, assuming bulk densities for the films, are 156 ± 7.5 GPa for VO2 (M1 phase) and 102 ± 3 GPa for Cr-doped VO2 (M2 phase). Strong curvature changes during the transition to the R phase were also observed for cantilevers coated with both types of films, but these were significantly higher in the case for the Cr-doped film. Curvature changes for temperature ranges outside the IMT region were small and attributed to differential thermal expansion between film and silicon substrate. From measured cantilever tip displacements in this post-transition range-for the undoped VO 2-coated microcantilevers-a rough estimate of 110 GPa was obtained for the effective Young's modulus for R-phase VO2. The substantially higher changes in resonant frequency and curvature for V1-xCr xO2-coated cant
This paper studies the application of the non-linear model (ANN, ANFIS). ANN and ANFIS were used to fit a Blood-Oxygen Level Dependent (BOLD) signal with design architecture. A model proposes to define region of inter...
详细信息
ISBN:
(纸本)9781467348904
This paper studies the application of the non-linear model (ANN, ANFIS). ANN and ANFIS were used to fit a Blood-Oxygen Level Dependent (BOLD) signal with design architecture. A model proposes to define region of interest (ROI) in brain fMRI images. The result shows the ANFIS model can be represent to fit the BOLD data better than ANN. Three paradigms were stimulated at difference issue activation in specific parameter (activation time, duration and signal strength). In this case a higher frequency and amplitude paradigm has stimulated on the brain area activation faster and more frequently.
Many organizations have now adopted Service Oriented Architecture （SOA） as an architectural style to help them with architecture, design and implementation of their core services and systems. Most of these organizat...
详细信息
Many organizations have now adopted Service Oriented Architecture （SOA） as an architectural style to help them with architecture, design and implementation of their core services and systems. Most of these organizations are challenged in integrating SOA style with their overall Enterprise Architecture work. This framework links an SOA style with the Enterprise Architecture （EA） methodologies to help organizations organize their SOA effort as a key part of their Enterprise Architecture. The case study demonstrates the implementation of architecture goal with organization vision in service oriented organizational structure using services that align Business with Technology. The framework is validated and has reserved the privileges of SOA and EA.
We solve the problem of model-independent semiglobal exponential practical stabilization for any linear time-varying single-input system under the assumption that the time-varying input vector, which is otherwise unkn...
详细信息
ISBN:
(纸本)9781457710957
We solve the problem of model-independent semiglobal exponential practical stabilization for any linear time-varying single-input system under the assumption that the time-varying input vector, which is otherwise unknown, satisfies a persistency of excitation condition over a sufficiently short window. We employ an extremum seeking algorithm, with the square of the norm of the state used as the cost function. The stability analysis is inspired by the approach in a recent work by Durr, Stankovic, and Johansson, which combines a Lie bracket second-order averaging result of Gurvits and Li with a perturbation theory semiglobal practical stability result of Moreau and Aeyels. As an alternative to the classical Nussbaum gain type of a design by Mudgett and Morse, when applied to time-invariant systems, our design gives up globality and perfect regulation to the origin but ensures exponential practical stabilization and prevents large overshoots that characterize the Nussbaum gain design when the initial estimate of the control direction is of the wrong sign. Furthermore, while the Nussbaum gain design leads to instability when the control direction periodically changes sign, our design guarantees stability.
The analysis of deep level defects of III-V nitrides (such as GaN or InxGa1-xN) is critical for the improvement of solar cell properties using these materials as an active layer. Schottky junctions are often used for ...
The analysis of deep level defects of III-V nitrides (such as GaN or InxGa1-xN) is critical for the improvement of solar cell properties using these materials as an active layer. Schottky junctions are often used for the detection of level defects by deep level transient spectroscopy or deep level optical spectroscopy. Masatomo Sumiya and coworkers (pp. 470–473) have fabricated a transparent conducting polymer / GaN Schottky junction by using spin coating technique. The Schottky properties exhibited an ideal factor of 1.3, a Schttoky barrier height of 1.15 eV and a leakage current at -10 V of ～10-6 mA/cm2, which was much better than that of a normal Schottky junction using a high workfunction metal like Au. Under irradiation of an AM1.5G solar simulator, the device performed an open circuit voltage of 0.72 V with a high fill factor of 0.71. Utilizing the features of transparency and good Schottky properties, the depletion layer in GaN at the interface beneath the conducting polymer was evaluated under light irradiation in order to detect the defects located in the GaN band-gap which must give an influence on the photovoltaic properties. This technique can be applied also to InGaN films with lower band-gap, even more suitable as photovoltaic material of III-V nitride film.
暂无评论