Space-time Characteristics and Experimental Analysis of Broadening First-order Sea Clutter in HF Hybrid Sky-surface Wave Radar

In high frequency (HF) hybrid sky-surface wave radar, the first-order sea clutter broadening is very complex and serious under the influence of ionosphere and bistatic angle, which affects the detection of ship target. This paper analyzes the space-time characteristics based on the HF sky-surface wave experimental system. We first introduce the basic structure, working principle and position principle based on our experimental system. Also analyzed is the influence of ionosphere and bistatic angle on the space-time coupling characteristics of broadening first-order sea clutter and the performance of space-time adaptive processing (STAP). Finally, the results of theoretic analysis are examined with the experimental data. Simulation results show that the results of experiment consist with that of theoretic analysis

Slowly rotating black holes in the Horava-Lifshitz gravity

We investigate slowly rotating black holes in the Ho\v{r}ava-Lifshitz (HL) gravity. For $\Lambda_W=0$ and $\lambda=1$, we find a slowly rotating black hole of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. We discuss their thermodynamic properties by computing mass, temperature, angular momentum, and angular velocity on the horizon.Comment: 12 pages, no figures, version to appear in EPJ

Distributed H∞-consensus filtering in sensor networks with multiple missing measurements: The finite-horizon case

The official published version of the article can be found at the link below.This paper is concerned with a new distributed H∞-consensus filtering problem over a finite-horizon for sensor networks with multiple missing measurements. The so-called H∞-consensus performance requirement is defined to quantify bounded consensus regarding the filtering errors (agreements) over a finite-horizon. A set of random variables are utilized to model the probabilistic information missing phenomena occurring in the channels from the system to the sensors. A sufficient condition is first established in terms of a set of difference linear matrix inequalities (DLMIs) under which the expected H∞-consensus performance constraint is guaranteed. Given the measurements and estimates of the system state and its neighbors, the filter parameters are then explicitly parameterized by means of the solutions to a certain set of DLMIs that can be computed recursively. Subsequently, two kinds of robust distributed H∞-consensus filters are designed for the system with norm-bounded uncertainties and polytopic uncertainties. Finally, two numerical simulation examples are used to demonstrate the effectiveness of the proposed distributed filters design scheme.This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant GR/S27658/01, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany

Short-segment posterior instrumentation combined with calcium sulfate cement vertebroplasty for thoracolumbar compression fractures: Radiographic outcomes including nonunion and other complications

AbstractObjectiveTo evaluate the radiographic outcomes of short-segment posterior instrumentation plus vertebroplasty using injectable calcium sulfate cement (CSC) for thoracolumbar compression fractures.Materials and methodsTwenty-eight patients with a single-level thoracolumbar compression fracture, who underwent short-segment pedicle screw fixation and CSC vertebroplasty, were included in the study. The anterior vertebral body height ratio, local kyphosis angle, and the height of the intervertebral disc adjacent to the fractured vertebra were used to evaluate the radiographic results. Complications including bone nonunion, instrument failure, cement leakage, and disc vacuum formation were also assessed.ResultsThe patients were followed up for an average of 24.20±5.40 months. The relative preoperative anterior body height was 55.71±15.29%, which improved to 94.93±5.39% immediately after surgery (P<0.001), and at final follow-up showed a 6.50±3.89% loss of height correction (P<0.001). The mean preoperative local kyphosis angle was 22.23±5.65°, which corrected to 2.67±4.43° immediately after surgery (P<0.001), but reverted to 6.71±4.95° at final follow-up, showing a 4.04±1.91° loss of correction (P<0.001). The mean height of the intervertebral disc proximal to the fractured vertebra was 9.87±0.91mm before surgery, 12.53±0.98mm after operation (P<0.001), and the loss of correction at final follow-up was 2.35±1.15mm with a significant difference compared to immediate postoperative values (P<0.001). Bone nonunion occurred in 7 patients, 2 patients had hardware failure, 9 patients had cement leakage, and 10 patients had disc vacuum phenomenon adjacent to the fractured vertebra.ConclusionsThe patients who underwent this procedure had a loss of correction of vertebral height and local kyphosis. Complications such as bone nonunion, instrument failure, cement leakage, and disc vacuum may occur. Rapid CSC resorption accounts for these radiographic outcomes and complications.Level of evidenceLevel IV, retrospective study

Aroma Evaluation of Young Chinese Merlot Wines with Denomination of Origin

Merlot wines from four premium wine-producing districts in China were analysed for their volatilecomposition and sensory properties. Fifty-seven aroma compounds were quantified by SPME-GC-MSOAVanalysis, which showed that thirty of these compounds were active on the basis of their odour active value(OAV). According to the aroma descriptions of eleven impact odorants in all the sample wines, the collectivearoma characteristics of Chinese Merlot red wine are complex. Its main flavour is that of some tropical andtemperate fruits, such as banana, pineapple, green apple, pear and strawberry, along with a lactic flavourfrom the malolactic fermentation. It also has some traits of processed fruits, Muscat and floral pollen flavour.Moreover, different districts gave Merlot wine distinct characters. Changli wine had a higher intensity andcomplexity of global aroma, a strong fruity aroma, and an obvious nuance of lactic and nut traits. Thesine from Helanshan had weak fusel flavour and some lemon fruity flavour. Shacheng wine had weak fuselflavour, along with green grass and some fruity flavour of raspberry and violet. Manasi wine had the odourof unpleasant fatty acids and phenol due to its high content of fatty acids and volatile phenol. The sensoryanalysis confirmed the aroma prediction from the active odorants of the sample wines. Changli wine hadthe highest sensory scores, while Manasi wine had the worst evaluation of aroma, taste and harmony. Theresults suggest that the Merlot variety is more suitable for planting in Changli than in the Manasi region

Basic reproduction number for HIV model incorporating commercial sex and behavior change

The basic reproduction number is obtained for an HIV epidemic model incorporating direct and indirect commercial sex as well as behavior change by the female commercial sex workers (CSWs) and their male customers in response to the proliferation of the disease in the community. A recent result by van den Driessche P., and Watmough J. (Math. Biosci. 180:29-48, 2002) is utilized to compute the threshold parameters for the local asymptotic stability of the Disease-Free Equilibrium (DIFE), by considering the transfers in and out of the infective classes. Numerical examples are used to describe the uniqueness and global properties of the endemic equilibrium when DIFE is unstable. Biological interpretation of the results obtained in this work is discussed, as are the implications of our results for the design of public health policies such as targeting strategy to target intervention and control measures toward specific high-risk population groups in order to reduce infections. We show that targeting any one sector of the commercial sex alone for prevention will be difficult to have a decided effect on eradicating the epidemic. However, if the aim of the targeted intervention policy is not eradication of the epidemic but decrease in HIV incidence of a particular high-risk group, then concentrated targeting strategy could be sufficient, if properly implemented. This work also demonstrates the usefulness of the theorem of van den Driessche and Watmough (Math. Biosci. 180:29-48, 2002) in obtaining threshold parameters for complicated infectious diseases models

Extremal black holes in the Ho\v{r}ava-Lifshitz gravity

We study the near-horizon geometry of extremal black holes in the $z=3$ Ho\v{r}ava-Lifshitz gravity with a flow parameter $\lambda$. For $\lambda>1/2$, near-horizon geometry of extremal black holes are AdS$_2 \times S^2$ with different radii, depending on the (modified) Ho\v{r}ava-Lifshitz gravity. For $1/3\le \lambda \le 1/2$, the radius $v_2$ of $S^2$ is negative, which means that the near-horizon geometry is ill-defined and the corresponding Bekenstein-Hawking entropy is zero. We show explicitly that the entropy function approach does not work for obtaining the Bekenstein-Hawking entropy of extremal black holes.Comment: 18 pages, v2:some points on Lifshitz black holes claified, v3: version to appear in EJP

Does entropic force always imply the Newtonian force law?

We study the entropic force by introducing a bound $S \le A^{3/4}$ between entropy and area which was derived by imposing the non-gravitational collapse condition. In this case, applying a modified entropic force to this system does not lead to the Newtonian force law.Comment: 11 pages, version to appear in EPJ

Role of the Brans-Dicke scalar in the holographic description of dark energy

We study cosmological application of the holographic energy density in the Brans-Dicke theory. Considering the holographic energy density as a dynamical cosmological constant, it is more natural to study it in the Brans-Dicke theory than in general relativity. Solving the Friedmann and Brans-Dicke field equations numerically, we clarify the role of Brans-Dicke field during evolution of the universe. When the Hubble horizon is taken as the IR cutoff, the equation of state (w_{\Lmd}) for the holographic energy density is determined to be 5/3 when the Brans-Dicke parameter \omg goes infinity. This means that the Brans-Dicke field plays a crucial role in determining the equation of state. For the particle horizon IR cutoff, the Brans-Dicke scalar mediates a transition from w_{\Lmd} = -1/3 (past) to w_{\Lmd} = 1/3 (future). If a dust matter is present, it determines future equation of state. In the case of future event horizon cutoff, the role of the Brans-Dicke scalar and dust matter are turned out to be trivial, whereas the holographic energy density plays an important role as a dark energy candidate with w_{\Lmd} =-1.Comment: 10pages, 3figures, version to appear in PL