Spectrum spatial structure characteristic analysis of remote sensing alteration information and interference factors

Based on the statistical characteristics of remote sensing data, the spatial geometric structure characteristics of spectral data and distribution of background, interference and alteration information in characteristic space were researched through the analysis of two-dimensional and three-dimensional scatter diagrams. The results indicate that the hyper-space of remote sensing multi-data aggregation belongs to low-dimensional geometric structure, i.e. hyperplane form, and anomalous point groups including alteration information usually dissociate out of hyperplane. Scatter diagrams of remote sensing data band are mainly presented as two distribution forms of single-ellipse and dual-ellipse. Clarifying the relations of three objects of background, disturbance and alteration information in remote sensing images provides an important technical thought and guidance for accurately detecting and extracting remote sensing alteration information.

Interference Resistance of Pentamaran Ship Model With Asymmetric Outrigger Configurations

An experimental investigation is performed to assess the relation of interference performance on the total resistance of a pentamaran model advancing in calm water. For this motivation, the total drag of the ship is performed for several values of asymmetric outrigger configuration and hull separation, altering the Froude number in the range 0.3–0.9. Our results indicate that remarkable changes in resistance require notable changes in transverse distance values （hull separation） when wave interference may occur. In addition, there is no single configuration that consistently outperforms the other configurations across the entire speed range and the optimum interference factor -0.2 appears at a Froude number of 0.45 in S/L=0.33 with the outrigger outer position： asymmetric outboard for A3 configuration.

Interlayer interference mechanism of multi-seam drainage in a CBM well:An example from Zhucang syncline

Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin of Zhina coal field, we study the generation mechanism of interlayer interference, propagation rules of reservoir pressure drop and influencing factors of gas productivity in CBM multi-seam drainage in the paper. On the basis of the actual production data of X-2 well of Zhucang syncline in Bide-Santang basin,by simulating the gas production process of a CBM well under the condition of multiple seam with COMET3 numerical simulation software, we analyze the influencing factors of gas productivity during the process of multi-seam drainage, and illuminate the interlayer interference mechanism of multiseam drainage. The results show that permeability, reservoir pressure gradient, critical desorption pressure and fluid supply capacity of stratum have great influence on gas productivity of multi-seam drainage while coal thickness has little influence on it. Permeability, reservoir pressure gradient and fluid supply capacity of stratum affect the propagation velocity of reservoir pressure drop and thereby affect the final gas productivity. Moreover, the influence of critical desorption pressure on gas productivity of multiseam drainage is reflected in the gas breakthrough time and effective desorption area.

Reentry Attitude Tracking Control for Hypersonic Vehicle with Reaction Control Systems via Improved Model Predictive Control Approach

This paper studies the reentry attitude tracking control problem for hypersonic vehicles(HSV)equipped with reaction control systems(RCS)and aerodynamic surfaces.The attitude dynamical model of the hypersonic vehicles is established,and the simplified longitudinal and lateral dynamic models are obtained,respectively.Then,the compound control allocation strategy is provided and the model predictive controller is designed for the pitch channel.Furthermore,considering the complicated jet interaction effect of HSV during RCS is working,an improved model predictive control approach is presented by introducing the online parameter estimation of the jet interaction coefficient for dealing with the uncertainty and disturbance.Moreover,considering the strong coupling effect between the yaw channel and roll channel,a coupled model predictive controller is designed by introducing the feedback of sideslip angle into the roll control channel to eliminate the coupling effect.Finally,the comparison simulations using the classical control method,MPC and IMPC approach are given to demonstrate the effectiveness and efficiency of the presented IMPC scheme.

Ship Resistance of Quadramaran With Various Hull Position Configurations

Multihull ships are widely used for sea transportation, and those with four hulls are known as quadramarans. Hull position configurations of a quadramaran include the diamond, tetra, and slice. In general, multihull vessels traveling at high speeds have better hydrodynamic efficiency than monohull ships. This study aims to identify possible effects of various quadramaran hull position configurations on ship resistance for hull dimensions of 2 m length, 0.21 m breadth, and 0.045 m thickness. We conducted a towing test in which we varied the hull spacing and speed at Fr values between 0.08 and 0.62 and measured the total resistance using a load cell transducer. The experimental results reveal that the lowest total resistance was achieved with a diamond quadramaran configuration at Fr = 0.1-0.6 and an effective interference factor of up to 0.35 with S/L = 3/10 and R/L = 1/2 at Fr = 0.62.

Resistance Characteristic of High-speed Unstaggered Pentamaran Model with Variations of Symmetric and Asymmetric Hull Configurations

Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull with the same displacement.The destructive interference between the system of waves produced by the vessel’s hulls might benefit the reduction of power consumption.This study investigated a Wigley hull form pentamaran model with five asymmetric and symmetric hull config-urations and three variations of hull separation.The ship model was towed in conditions of fixed towing and calm water with Froude numbers(Fr)ranging from 0.55 to 1.00.A resistance analysis had been carried out to ensure proper comparison between the asymmetric and symmetric hull configurations.Results showed that total resistance coefficient of the asymmetries created different properties from the symmetries,that is,symmetries produced steadier trends than asymmetries.The hull separation variation caused a slight alteration in the total resistant coefficient(in magnitude)under the same configuration.Although not a single configuration outperformed the others in the entire range of Fr,three configurations were noteworthy as optimum models based on their Fr range.Moreover,a configuration of asymmetric hull with S/L=0.22 could generate a constant destructive interference throughout the investigated Fr range.

Comparative Analysis of the Separation Variation Influence on the Hydrodynamic Performance of a High Speed Trimaran

This paper numerically investigates the influence of separation variation of the outriggers on the hydrodynamic performance of a high speed trimaran （HST） aiming at improving its applicability in diverse realistic disciplines. The present investigation was performed within the framework of the 2-D slender body method （SBM） by calculating the resistance of three symmetric trimaran series moving in a calm free surface of deep water. Each trimaran series comprises of 4681 configurations generated by considering 151 staggers （-50%≤a≤＋ 100%）, and 31 separations （100%≤β≤400%） for 81 Froude numbers （0.20≤Fn≤ 1.0）. In developing the three trimaran series, Wigley-st. AMECRC-09, and NPL-4a models were used separately for both the main and side hulls of each individu;d series models. A computer macro named Tri-PL was created using the Visual Basic for Applications~. Tri-PL~ sequentially interfaced Maxsurfe then Hullspeed to generate the models of the three trimaran series together with their detailed hydrostatic particulars, followed by their resistance components. The numerical results were partially validated against the available published numerical calculations and experimental results, to benchmark the Tri-PL macro and hence to rely on the analysis outcomes. A graph template was creaLed within the framework of SigmaPlot to visualize the significant results of the Tri-PL properlv.

Small interference RNA targeting vascular endothelial growth factor gene effectively attenuates retinal neovascularization in mice model

Background The mechanism of retinal neovascularization is not understood completely. Many growth factors are involved in the process of retinal neovascularization, such as vascular endothelial growth factor （VEGF） and pigment epithelium-deprived factor （PEDF）, which are the representatives of angiogenic and antiangiogenic molecules respectively. Oxygen induced retinopathy （OIR） is a useful model to investigate retinal neovascularization. The present study was conducted to investigate the feasibility of small interference RNA （siRNA） targeting VEGF gene in attenuating oxygen induced retinopathy （OIR） by regulating VEGF to PEDF ratio （VEGF/PEDF）. Methods In vitro, cultured EOMA cells were transfected with VEGF-siRNA （psi-HITM/EGFPNEGF siRNA） and LipofectamineTM 2000 for 24, 48, and 72 hours, respectively. Expression of VEGF mRNA was evaluated by real time polymerase chain reaction （PCR） and the level of VEGF protein was analyzed by Western blotting. In vivo, OIR model mice were established, the mice （C57BL/6J） received an intra-vitreal injection of μ1 of mixture of psi-HITM/EGFPNEGF siRNA and Lipofectamine 2000. Expressions of retinal VEGF and PEDF protein were measured by Western blotting, retinal neovascularization was observed by fluorescein angiography, and quantified. Results In vitro psi-HITM/EGFPNEGF siRNA treatment significantly reduced VEGF mRNA and protein expression. In vivo, with decreased VEGF and VEGF-PEDF ratio, significant attenuation of neovascular tufts, avascular regions, tortuous, and dilated blood vessels were observed in the interfered animals. Conclusions VEGF plays an important role in OIR, and the transfection of VEGF-siRNA can effectively downregulate VEGF expression in vivo, accompanied by the downregulation of VEGF-PEDF ratio, and simultaneous attenuation of retinal neovascularization was also observed. These findings suggest that VEGF/PEDF may serve as a potential target in the treatment of retinal neovascularization and RNA interference targeting VEGF expression, which represents a possible therapeutic strategy.

Cells grouping scheme against pilot contamination in large scale antennas system

The influence of cells groupings factor to the performance of the cells groupings time-shift pilot scheme is researched for the multiple cells large scale antennas systems（LSAS）. The former researches have confirmed that the cells groupings time-shift pilots scheme is effective to reduce inter-cell interference, especially pilot contamination, which results from the pilot reuse in adjacent cells. However, they have not specified reasonable cells groupings factor, which plays a critical role in the general performance of the LSAS. Therefore, this problem is researched in details. The time for reverse-link data transmission will be compressed, when the groupings factor surpasses a certain range. Thus it is not always beneficial to increase the cells groupings factor without limitation. Furthermore,a reasonable cells groupings factor is deduced from the perspective of optimization to enhance the system performance. Simulations verify the proposed cell grouping factor.

Inhibition of vascular endothelial growth factor gene expression by T7-siRNAs in cultured human retinal pigment epithelial cells

Background Retinal pigment epithelial (RPE) cells play an important role in the occurrence of choroidal neovascularization (CNV). Vascular endothelial growth factor (VEGF) as a positive regulatory growth factor is produced by the RPE in an autocrine or paracrine manner, promoting CNV development. Duplexes of 21 nt RNAs, known as short interfering RNAs (siRNAs), efficiently inhibit gene expression by RNA interference when introduced into mammalian cells. We searched for an efficient siRNA to interfere with VEGF expression in RPE cells and shed light on the treatment of CNV.Methods Human primary RPE (hRPE) cells were cultured and identified. Three pairs of siRNAs were designed according to the sequence of VEGF 1-5 extrons and synthesized by T7 RNA polymerase transcription in vitro. To evaluate the inhibitory activity of T7-siRNAs, hRPE cells were transfected via siPORT Amine. The interfering effect of T7-siRNAs in hRPE cells was examined by semiquantitative reverse transcription-polymerase chain reaction and immunofluorescence. Results Three pairs of T7-siRNAs synthesized by in vitro transcription with T7 RNA polymerase suppressed VEGF gene expression with efficiency from 65% to 90%. T7-siRNA (B), targeted region at 207 nt to 228 nt and double stranded for 21 nt with 2 nt UU 3’ overhangs, was the most effective sequence tested for inhibition of VEGF expression in hRPE cells. Compared with nontransfected cells, the mean fluorescence in hRPE cells transfected with T7-sRNAs was significantly less (P<0.01). siRNA with a single-base mismatch and ssRNA(+) did not show suppressing effect. Furthermore, it was found that siRNAs had a dose dependent inhibitory effect (5 to 10 pmol).Conclusion T7-siRNA can effectively and specifically suppress VEGF expression in hRPE cells and may be a new way to treat CNV.