Design of Small MEMS Microphone Array Systems for Direction Finding of Outdoors Moving Vehicles

In this paper, a MEMS microphone array system scheme is proposed which implements real-time direction of arrival (DOA) estimation for moving vehicles. Wind noise is the primary source of unwanted noise on microphones outdoors. A multiple signal classification (MUSIC) algorithm is used in this paper for direction finding associated with spatial coherence to discriminate between the wind noise and the acoustic signals of a vehicle. The method is implemented in a SHARC DSP processor and the real-time estimated DOA is uploaded through Bluetooth or a UART module. Experimental results in different places show the validity of the system and the deviation is no bigger than 6° in the presence of wind noise

Leakage performance of labyrinth seal for oil sealing of aero-engine

Experimental investigation has been done to evaluate the leakage performance of labyrinth seal for oil sealing on high-speed sealing test rig at different working and geometric parameters. Typical values of pressure ratio ranging from 1.0 to 2.0 were used and the rotating speed varied from 0 to 30,000 rpm. Dimensionless Taylor number was invited to response the effect of rotation. Oil was injected at the rate from 1.2 L/min to 2.8 L/min to check the sealing capacity. Leakage was measured at different seal configurations including sealing clearance, tooth tip thickness, pitch, teeth number, front inclined angle and oil-throwing angle. Different from gas sealing, the application of oil-throwing tooth in oil sealing attracted much interest as an obvious alternative to the conventional labyrinth seal. A blocking ring was captured during testing, which establishes understanding of underlying flow mechanisms in the clearance and plays an important role in oil sealing. There is a critical Taylor number at which the leakage coefficient drops drastically. After the critical Taylor number, a parabola rule appears. An optimal composition of tooth tip thickness, teeth number, oil-throwing angle and front inclined angle exists where the leakage performance behaves better. Keywords: Labyrinth seal, Leakage, Rotating, Oil sealing, Aero-engin

Acoustic Source Localization via Subspace Based Method Using Small Aperture MEMS Arrays

Small aperture microphone arrays provide many advantages for portable devices and hearing aid equipment. In this paper, a subspace based localization method is proposed for acoustic source using small aperture arrays. The effects of array aperture on localization are analyzed by using array response (array manifold). Besides array aperture, the frequency of acoustic source and the variance of signal power are simulated to demonstrate how to optimize localization performance, which is carried out by introducing frequency error with the proposed method. The proposed method for 5 mm array aperture is validated by simulations and experiments with MEMS microphone arrays. Different types of acoustic sources can be localized with the highest precision of 6 degrees even in the presence of wind noise and other noises. Furthermore, the proposed method reduces the computational complexity compared with other methods

Bovine <i>HOXA11</i> Gene Identified from <i>RNA-Seq</i>: mRNA Profile Analysis and Genetic Variation Detection Using ME Method and Their Associations with Carcass Traits

The Homeobox A11 (HOXA11) gene regulates limb skeletal development and muscle growth, thus, it was selected as a candidate gene for bovine carcass traits. In this study, we analyzed the mRNA expression level of HOXA11 in various tissues and cells, and determined the genetic variations in the HOXA11 gene, which might be used as molecular markers for cattle breeding. The mRNA expression profiles of HOXA11 in bovine different tissues showed that HOXA11 was highly expressed in both fat and muscle. The gene expression trend of HOXA11 in myoblasts and adipocytes indicated that HOXA11 might be involved in the differentiation of bovine myoblasts and adipocytes. The data in the Ensembl database showed that there are two putative insertion/deletion (InDel) polymorphisms in the bovine HOXA11 gene. The insertion site (rs515880802) was located in the upstream region (NC_037331.1: g. 68853364-68853365) and named as P1-Ins-4-bp, and the deletion site (rs517582703) was located in the intronic region (NC_037331.1: g. 68859510-68859517) and named as P2-Del-8-bp. These polymorphisms within the HOXA11 gene were identified and genotyped by PCR amplification, agarose gel electrophoresis and DNA sequencing in the 640 Shandong Black Cattle Genetic Resource (SDBCGR) population. Moreover, the mutation frequency was very low after detection, so the mathematical expectation (ME) method was used for detection. Statistical analysis demonstrated that P1-Ins-4-bp was significantly correlated with the beef shoulder (p = 0.012) and tongue root (p = 0.004). Meanwhile, P2-Del-8-bp displayed a significant correlation with the back tendon (p = 0.008), money tendon (p = 2.84 × 10-4), thick flank (p = 0.034), beef shin (p = 9.09 × 10-7), triangle thick flank (p = 0.04), triangle flank (p = 1.00 × 10-6), rump (p = 0.018) and small tenderloin (p = 0.043) in the female SDBCGR population. In summary, these outcomes may provide a new perspective for accelerating the molecular breeding of cattle through marker-assisted selection (MAS) strategies

Parallel acceleration of vegetation growth rate and senescence rate across the Northern Hemisphere from 1982 to 2015

Growth and senescence rates are critical ecological indicators of seasonality shifts of vegetation, with both sensitive to climate change. Here we investigated daily mean vegetation growth and senescence rates, and the major climate forcing across the Northern Hemisphere (>30°N) using satellite-derived normalized difference vegetation index (NDVI) and flux-based gross primary productivity (GPP) from 1982 through 2015. Both growth and senescence rates are higher at high latitudes than those at low latitudes, with spatially-averaged values increased by 1.0 × 10−4 and 0.7 × 10−4 NDVI-units·day−1 per degree latitude. These increases were greater in Eurasia than in North America. A parallel acceleration of growth (0.8 ×10−4 NDVI-units·day−1·decade−1) and senescence (0.6 ×10−4 NDVI-units·day−1·decade−1) rates was found for the 34-year study period. The warming-induced increases in vegetation peak growth (peak NDVI) contributed strongly to this parallel acceleration, while unequal advances or delays of three key phenological indicators (the start (SOS), peak (POS), and end (EOS) of the growing season) exerted influential effects on the rates. However, no single climatic factor during any period appeared responsible for the variations in growth and senescence rates. In areas with growth and senescence rates that are determined by peak growth, temperature and precipitation during the growth period accelerated both rates through elevating peak growth. On the other hand, in areas with growth rate determined by SOS, rising temperature before SOS decelerated the growth rate by advancing SOS. In areas with senescence rate determined by EOS, both temperature and radiation during the senescence period contributed to changes in senescence rate by influencing EOS. In sum, a central focus should be placed on the linkages among climate, phenology, and growth and senescence rates for quantifying vegetation seasonality and associated ecosystem function under the changing climate

Integration and Comparison of Multiple Two-Leaf Light Use Efficiency Models Across Global Flux Sites

Accurate estimation of gross primary productivity (GPP) from the regional to global scale is essential in modeling carbon cycle processes. The recently-developed two-leaf light use efficiency (TL-LUE) model and its revised versions based on different concepts have significantly improved the underlying mechanisms between model assumptions and photosynthetic processing. Yet few studies have compared the advantages of the various two-leaf LUE models for their practical applications. Here, an integrated model referred to as a three-parameter radiation-constrained mountain TL-LUE (RMTL3-LUE) is proposed by combining the radiation scalar of the [radiation-constrained TL-LUE model] and the topographic parameters of the [mountainous TL-LUE model]. In this way, the importance of light intensity and topography on vegetation photosynthesis is integrated. Our calibration and validation of RMTL3-LUE were carried out for 11 ecosystems with in situ eddy covariance measurements around the globe. This indicates that the model can effectively improve the GPP estimates compared with its predecessors. At the landscape scale, RMTL3-LUE can also realistically quantify topographic effects on photosynthesis, with topographic sensitivities of decreasing (increasing) with the slope on the unshaded (shaded) terrain. Furthermore, RMTL3-LUE displays an asymmetric sensitivity to PAR variability, with a low sensitivity to PAR compared with other models under high PAR conditions and a similar sensitivity to PAR in low PARs. Altogether, it is clear that the integration of the merits of multiple TL-LUE models can further improve the photosynthetic processes for various conditions amid more challenges in constructing more complex models

Leakage Performance of Floating Ring Seal in Cold/Hot State for Aero-engine

© 2019 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/Rotating experimental investigations were carried out to study the oil sealing capability of two different floating ring seals in cold/hot state for aero-engine. High-speed floating ring seal (HFRS) is a seal with the inner diameter of 83.72mm and maximum speed of 38000rpm, and Low-speed floating ring seal (LFRS) is another seal with the inner diameter of 40.01mm and maximum speed of 18000rpm. In hot state, sealing air with the temperature of 371K and oil with the temperature of 343K was employed to model the working conditions of an aero-engine. Comparisons between floating ring seal and labyrinth seal were done to inspect the leakage performance. More attention was paid to the critical pressure ratio where the oil leakage began. Results show that the critical pressure ratio in cold state is obviously larger than that in hot state for both seals. An underlying sealing mechanism for floating ring seal is clarified by the fluid film, which closely associates with the dimensionless parameter of 2c/Dr. Another fantastic phenomenon is that the leakage coefficient in hot state, not the leakage magnitude, is unexpectedly larger than that in cold state. Overall, the leakage performance of the floating ring seal is better than the labyrinth seal.Peer reviewe

Pancreatic adenosquamous carcinoma: A population level analysis of epidemiological trends and prognosis

Abstract Background The incidence and mortality of pancreatic adenosquamous carcinoma (PASC) have received little attention. The goal of our study was to explore the overall epidemiological trend of PASC at the population level. Methods The Surveillance, Epidemiology, and End Results database was used to collect the incidence, incidence‐based (IB) mortality, and patient details for PASC from 2000 to 2017. The Joinpoint regression tool was used to examine the trends in incidence and IB mortality. The Kaplan–Meier approach was used for survival analysis. Univariate and multivariate Cox regression analyses were used to determine the independent prognostic factors. Results We included 815 patients with PASC in the study. The incidence of PASC continuously increased from 2000 to 2017, with an annual percentage change (APC) of 3.9% (95% CI: 2.2%–5.7%, p < 0.05). IB mortality also increased continuously, with an APC of 5.0% (95% CI: 2.5%–7.6%, p < 0.05). Multivariate Cox regression analysis revealed that age, treatment, regional lymph node involvement, and tumor size were independent prognostic factors. Nomograms were created for PASC to predict 1‐ and 2‐year survival probabilities, respectively. Conclusions The incidence and IB mortality of PASC had a sustained and rapid increase, indicating that the preventive and treatment measures for PASC were not ideal. We must identify the significance of this condition as soon as possible, and commit greater attention and resources to PASC research