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A nonlinear station-keeping control method for a multi-vectored propeller airship under unknown wind field with thrust saturation is developed, which is composed of three modules: nonlinear model predictive controller (NMPC), disturbance observer (DOB) and tracking differentiator (TD). The nonlinear kinematics and dynamics models are introduced, and the wind effect is considered by the wind-induced aerodynamic force. Based on both models, an explicit NMPC is designed. Then a nonlinear DOB is introduced to estimate the wind disturbance. A TD, showing the relationship between the maximum propulsion force and the maximum flight acceleration, is proposed to handle the thrusts’ amplitude saturation. Stability analysis shows that the closed-loop system is globally asymptotically stable. Simulations for a multi-vectored propeller airship are conducted to demonstrate the robustness and effectiveness of the proposed method.
Superior and inferior rice grains have different weights and are located on the upper primary branch and lower secondary branches of the panicle, respectively. To study differences in germination vigour of these two types of grain, a number of factors were investigated from 0 to 48 h of germination. The present study demonstrated that in inferior grains the starch granule structure was looser at 0 h, with full water absorption at 48 h, while in superior grains the structure was tight and dense. Relative water content increased, and dry matter decreased, more rapidly in inferior grains than in superior ones. Abscisic acid and gibberellin levels, as well as α-amylase activity, also changed more rapidly in inferior grains, while soluble sugar content and amylase coding gene expression increased more rapidly in inferior than superior grains during early germination. The expression of OsGAMYB was higher in inferior grains at 24 h but higher in superior grains at 48 h. The phenotypic index of seedlings was higher in seedlings from superior grains at the two-leaf stage. However, the thousand-grain weight and yield per plant in superior and inferior plants showed no significant difference at harvest. The present study indicates that inferior grains germinate faster than superior ones in the early germination stage. Although inferior grains produced weaker seedlings, it is worthwhile using them in rice production due to their comparative yield potential over that of superior grains.
In this study, the biomass of winter wheat was estimated by using hyperspectral data obtained from a hyperspectral camera on an Unmanned Aerial Vehicle (UAV). Every two bands from the hyperspectral data were selected to calculate two kinds of vegetation indexes: the Normalized Difference Vegetation Index (NDVI) and Ratio Vegetation Index (RVI). Linear models were established between winter wheat biomass and those indexes, and coefficient of determination R2 was used to draw the two-dimensional distribution of R2 values. The comparison between NDVI and RVI for pixel covered by soil and wheat showed that RVI is more efficient to mask the influence from soil than NDVI. For calculating the NDVI, optimal bands are located mainly around 820 nm and 725 nm to 750 nm. For assessing RVI, the wavelength range from 820 to 832 nm, 794 to 808 nm, 770 to 788 nm, 725 nm to 750 nm and 890 nm for RVI are most suitable. Those optimal bands can achieve a coefficient of determination R2 higher than 0.88 by using the linear regression model in the study.
Bacillary dysentery continues to be a major health issue in developing countries and ambient temperature is a possible environmental determinant. However, evidence about the risk of bacillary dysentery attributable to ambient temperature under climate change scenarios is scarce. We examined the attributable fraction (AF) of temperature-related bacillary dysentery in urban and rural Hefei, China during 2006–2012 and projected its shifting pattern under climate change scenarios using a distributed lag non-linear model. The risk of bacillary dysentery increased with the temperature rise above a threshold (18·4 °C), and the temperature effects appeared to be acute. The proportion of bacillary dysentery attributable to hot temperatures was 18·74% (95 empirical confidence interval (eCI): 8·36–27·44%). Apparent difference of AF was observed between urban and rural areas, with AF varying from 26·87% (95% eCI 16·21–36·68%) in urban area to −1·90% (95 eCI −25·03 to 16·05%) in rural area. Under the climate change scenarios alone (1–4 °C rise), the AF from extreme hot temperatures (>31·2 °C) would rise greatly accompanied by the relatively stable AF from moderate hot temperatures (18·4–31·2 °C). If climate change proceeds, urban area may be more likely to suffer from rapidly increasing burden of disease from extreme hot temperatures in the absence of effective mitigation and adaptation strategies.
In order to avoid excess feed consumption during the force-feeding period in foie gras production, a dose-response experiment with seven feed consumption levels (450, 540, 630, 720, 810, 900, 990 g/day per bird) was conducted to evaluate the effects of feed consumption levels on growth performance and carcass composition of male Mule ducks from 91 to 102 days of age. One-day-old Mule ducklings (sterile and artificial hybrid of male Albatre Muscovy duck and female Pekin duck were fed a two-phase commercial diets for ad libitum intake from hatching to 91 days of age, followed by graded feeding levels of a corn diet by force-feeding from 91 to 102 days of age. Fifty-six 91-day-old male Mule ducks with similar BW were randomly assigned to seven treatments, with eight birds per treatment. Birds were housed in individual pens. At 102 days of age, final BW was measured and BW gain and feed conversion ratio of ducks from each treatment were calculated from day 91 to 102, and then all ducks were slaughtered to evaluate the yields of skin with subcutaneous fat, abdominal fat, breast meat (including pectoralis major and pectoralis minor), leg meat (including thigh and drum stick), and liver. Significant differences in BW gain, total liver weight and liver relative weight were observed among the treatments (P<0.001). According to the broken-line regression analysis, the optimal feed consumption levels of male Mule ducks from 91 to 102 days of age for maximum BW gain, total liver weight and liver relative weight were 217, 227 and 216 g feed/kg BW0.75·per day, respectively.
A stratospheric airship flies at a working altitude of 20km when it takes off from the ground. During ascent and descent, the wind field and thermal environment are highly complex. The thermal environment affects altitude, whereas wind influences the horizontal position of the airship. At a low altitude, this horizontal position cannot be controlled by thrusts given the low thrust-to-weight ratio, especially under a large wind field. However, it may be controlled indirectly by the pitch angle during ascent and descent with a certain vertical velocity. This study therefore proposes ascending and descending schemes for a stratospheric airship based on the thermal model. In this model, altitude is determined by the net lift/weight, whereas the horizontal position is controlled by the thrust and pitch. The pitch angle is determined by ballonets and an elevator. To allocate pitch control between the ballonets and the elevator under different airspeeds, pseudo-inverse dynamics of varied weight are introduced. In horizontal position control, the method of chain allocation is then applied between a pitch angle and vectored thrust to control the position of a stratospheric airship during ascent/descent.
Co-infections of cystic echinococcosis (CE) and HIV/AIDS is rare. We report four CE cases that were HIV positive. Three out of the four patients underwent a surgical operation to remove the hydatid cysts in their livers. The operation confirmed that in two of the cases their cysts had ruptured. These patients were given 3 months of albendazole after the operation. Follow-up showed they were remarkably improved in term of their health, although they were still HIV antibody positive 6 months after surgical treatment. Interestingly, the treatment remarkably increased their CD4+ cell population. We showed that surgery is suitable for treating hepatic cystic echinococcosis with HIV/AIDS co-infection.
To understand the clinical epidemiology and molecular characteristics of human bocavirus (HBoV) infection in children with diarrhoea in Guangzhou, South China, we collected 1128 faecal specimens from children with diarrhoea from July 2010 to December 2012. HBoV and five other major enteric viruses were examined using real-time polymerase chain reaction. Human rotavirus (HRV) was the most prevalent pathogen, detected in 250 (22·2%) cases, followed by enteric adenovirus (EADV) in 76 (6·7%) cases, human astrovirus (HAstV) in 38 (3·4%) cases, HBoV in 17 (1·5%) cases, sapovirus (SaV) in 14 (1·2%) cases, and norovirus (NoV) in 9 (0·8%) cases. Co-infections were identified in 3·7% of the study population and 23·5% of HBoV-positive specimens. Phylogenetic analysis revealed 14 HBoV strains to be clustered into species HBoV1 with only minor variations among them. Overall, the detection of HBoV appears to partially contribute to the overall detection gap for enteric infections, single HBoV infection rarely results in severe clinical outcomes, and HBoV sequencing data appears to support conserved genomes across strains identified in this study.
We are developing a purely commensal survey experiment for fast (<5 s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.
Pneumonia is an important cause of mortality and morbidity in infants. However, information of risk factors for pneumonia in children aged <6 months is limited. This study aimed to evaluate the risk factors and their contribution to infantile pneumonia in a large population-based survey. Of 24 200 randomly sampled main caregivers invited, 21 248 (87·8%) participated in this study. A structured questionnaire was used to interview the main caregivers. Information regarding whether hospitalization was required, family environment, and medical history were obtained. The prevalence of pneumonia was 0·62% in our study cohort. Multivariate logistic regression analysis showed that preterm birth, congenital cardiopulmonary disease, antibiotic use during pregnancy, maternal overweight, daily prenatal exposure to environmental tobacco smoke, maternal smoking during pregnancy, and visible mould on walls at home are risk factors associated with infantile pneumonia. Further study is warranted to investigate the causality and mechanisms of these novel factors.
The aortic pulse wave velocity (PWV) is a useful clinical index to assess the aortic compliance and cardiovascular risk in a noninvasive manner. In this research, our previously developed axial velocity profile method (Yu et al., ) was modified to be more user-friendly and applied to the study of PWV of diabetic patients for the first time, using phase-contrast magnetic resonance imaging (PC-MRI) technique to analyze the spatial and temporal profiles of the axial velocity along the descending aorta for measurement of the aortic PWV. The PWV results from healthy volunteers and diabetic patients were studied and compared. It is shown that the PWV of diabetic patients is much higher than that of health volunteers, the aortic compliance of diabetic patients is substantially worse than that of health volunteers. These results are in good agreement with early studies using different measurement techniques of PWV. The axial velocity profile method is again validated and proven to be a useful tool of long-term prognosis for patients with diabetes mellitus or hypertension.
Crystalline bismuthates Ba1−xKxBiO3 with x greater than 0.5 are obtained by a low temperature anodic electrocrystallization method in a potassium hydroxide molten flux. The x = 0.56 bismuthate crystal shows 8K superconductivity determined by AC magnetic susceptibility.
We have grown and characterized epitaxial NbxTi1-xO2 on TiO2(110) and (100) for the purpose of investigating the role of chemically-inequivalent metal atoms on the thermal and photocatalytic properties of TiO2. Our goal is to introduce, in a highly controlled fashion, a Group VA transition metal into the lattice of a Group IVA transition metal oxide without altering the crystallographic structure. So doing would alter the electronic structure in interesting and potentially useful ways by the addition of one valence electron per substituted metal atom. However, strain builds in the film as more Nb is added at a rate which depends on the crystallographic orientation of the growth direction. Films grown along (110) can accommodate Nb mole fractions as high as ˜0.3 without forming misfit dislocations, whereas those grown along (100) are limited to ˜10 at. % Nb. Nb-O bond lengths in NbxTil−xO2 are the same as Ti-O bond lengths in pure TiO2 prior to the onset of dislocation formation. The extra 4d valence electron per Nb atom forms a nonbonding band which is degenerate with bonding states in the valence band region.
We proposed a concise and novel scheme to determine the crystallographic misorientation of heteroepitaxial structures. In addition to subtle high-resolution transmission electron microscope images, the information revealed from selected-area diffraction patterns at the interfaces offers another path to determine the angles of misorientations. The principle is to extract the basically three-dimensional misorientation information from a two-dimensional selected-area diffraction pattern through the employment of the Laue circle
Dielectric layers of thin silicon carbon nitride (SiCxNy) films have been prepared by ion beam sputtering deposition (IBD). For submicron metal-insulator-Si (MIS) based device applications, a dielectric of low interface roughness, increased capacitance/area with lower leakage on decreasing scale is highly desirable. We address these aspects for the IBD SiCxNy films on p-type Si and present their structural, optical and electrical characteristics as a function of the deposition conditions. Ultraviolet-visible transmittance and spectroscopic ellipsometry were employed to study the optical properties of the SiCxNy films. For electrical measurements, Al gate electrodes were fabricated on SiCxNy films to form metal-nitride-silicon (MNS) diodes. Characteristic I-V and photoconductivity measurements of the MNS are presented.
We report on deposition and properties of m-plane GaN/InGaN/AlInN structures on LiAlO2 substrates grown by metal organic vapor phase epitaxy (MOVPE). At first, two different buffer structures, one of them including an m-plane AlInN interlayer, were investigated concerning their suitability for the subsequent coalesced single-phase m-plane GaN growth. A series of quantum well structures with different well thickness based on one of these buffers showed absence of polarization-induced electric fields verified by room temperature photoluminescence (RT PL) measurements at different excitation intensities. Furthermore, polarization-resolved PL measurements revealed a high degree of polarization (DoP) of the emitted light with an intensity ratio of 8:1 between light polarized perpendicular and parallel to the c-axis.