The aerodynamic lift forces, lateral forces and rolling moment on high-speed power cars were investigated experimentally to study the effects of crosswinds on the aerodynamics of EMU (electric multiple unit). The dynamics of curve negotiation of high-speed power car under crosswinds was analyzed using software SIMPACK. The results indicate that wheel load reduction induced by crosswind is an important safety factor. Under discussed conditions, the safe speed of power car is less than 220 km/h under a mild wind ((15 m/s)); and there is no safe speed under a gust crosswind ((25 m/s)) when power cars run at speed of 100 ~ 180 km/h.
Abstract In this paper, a new guidance strategy is proposed for achieving precise control of time-varying velocity aircraft with impact time and angle constraints. Traditional guidance laws assume a constant velocity of the aircraft, but the velocity varies with time in practical scenarios, which affects the guidance accuracy under impact time and angle constraints. To overcome these difficulties, a guidance strategy consisting of trajectory generation and trajectory tracking is proposed. Firstly, the reference trajectory is constructed based on the Bezier spiral, which naturally satisfies the impact angle constraint. Then, the control problem of the impact time is transformed into an adjustment problem of the trajectory length. The expression of Bezier spiral that is only related to the curvature is derived, and a new lemma describing the relationship between trajectory length and curvature is found. Furthermore, the differential flatness property of the control system is explored to design a trajectory tracking method for Bezier spiral trajectory, which applies feedback linearization of the system through higher-order information. Finally, Numerical simulations confirm the superiority of the proposed method and validate the analytic findings.
Abstract This article studied a novel method for extrusion‐printing additive manufacturing (AM) of composite solid propellant by fast curing isocyanated‐HTPB and HTPB, which were blended and extruded via a static mixer. The gel time and tack‐free time of isocyanated‐HTPB with HTPB or diamines were extensively studied to screen for the potential formulation of extrusion‐printing. Upon the results of computational fluid dynamics simulation on the mixing effect of the static mixer, the formulation with 7 min gel time and 2.5 h tack‐free time was selected for extrusion‐printing experiment. The shape retaining characteristic of the formulations with 72 wt %, 75 wt %, 80 wt %, and 85 wt % solid content was qualitatively studied by printing the points, fibers, fiber arrays, and multilayer samples under fixed printing parameters, such as the slurry flux, the nozzle moving speed, and air pressure etc. The results showed that the curing rate and solid content play an important role in the free standing property of the slurry printed. A 3D sample with a complex geometric shape, which has 15 layers,18.5 mm in height, and 20.1 mm in outer diameter, was successfully extrusion‐printed by fast curing the slurry with the formulation of 85 wt % solid content. Its tensile strength and elongation at break are 0.33 MPa and 39.9 %, respectively. SEM observation showed that the internal morphology of the sample printed is dense and uniform. The results demonstrated that extrusion‐printing AM by fast curing two components is a potential candidate AM method for composite solid propellants with high solid content.
Abstract We present a real‐time approach for acquiring 3D objects with high fidelity using hand‐held consumer‐level RGB‐D scanning devices. Existing real‐time reconstruction methods typically do not take the point of interest into account, and thus might fail to produce clean reconstruction results of desired objects due to distracting objects or backgrounds. In addition, any changes in background during scanning, which can often occur in real scenarios, can easily break up the whole reconstruction process. To address these issues, we incorporate visual saliency into a traditional real‐time volumetric fusion pipeline. Salient regions detected from RGB‐D frames suggest user‐intended objects, and by understanding user intentions our approach can put more emphasis on important targets, and meanwhile, eliminate disturbance of non‐important objects. Experimental results on real‐world scans demonstrate that our system is capable of effectively acquiring geometric information of salient objects in cluttered real‐world scenes, even if the backgrounds are changing.
In the era of multimedia and Internet, people are eager to obtain information from offline to online. Quick Response (QR) codes and digital watermarks help us access information quickly. However, QR codes look ugly and invisible watermarks can be easily broken in physical photographs. Therefore, this paper proposes a novel method to embed hyperlinks into natural images, making the hyperlinks invisible for human eyes but detectable for mobile devices. Our method is an end-to-end neural network with an encoder to hide information and a decoder to recover information. From original images to physical photographs, camera imaging process will introduce a series of distortion such as noise, blur, and light. To train a robust decoder against the physical distortion from the real world, a distortion network based on 3D rendering is inserted between the encoder and the decoder to simulate the camera imaging process. Besides, in order to maintain the visual attraction of the image with hyperlinks, we propose a loss function based on just noticeable difference (JND) to supervise the training of encoder. Experimental results show that our approach outperforms the previous method in both simulated and real situations.
Acta Geologica Sinica - English EditionVolume 88, Issue s2 p. 1319-1320 Meeting Abstracts Geological Condition of Molybdenum Mineralization, Dongwuqi, Inner Mongolia Deyan ZHANG, Corresponding Author Deyan ZHANG College of Earth Sciences, Chengdu University of Technology, Chengdu 610059 Sichuan, ChinaCorresponding author. E-mail: zhang_deyan_cool@126.comSearch for more papers by this authorFang XIANG, Fang XIANG Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059 ChinaSearch for more papers by this authorKang CHEN, Kang CHEN Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059 ChinaSearch for more papers by this authorYao LIU, Yao LIU College of Earth Sciences, Chengdu University of Technology, Chengdu 610059 Sichuan, ChinaSearch for more papers by this authorXuyuan HAN, Xuyuan HAN College of Earth Sciences, Chengdu University of Technology, Chengdu 610059 Sichuan, ChinaSearch for more papers by this author Deyan ZHANG, Corresponding Author Deyan ZHANG College of Earth Sciences, Chengdu University of Technology, Chengdu 610059 Sichuan, ChinaCorresponding author. E-mail: zhang_deyan_cool@126.comSearch for more papers by this authorFang XIANG, Fang XIANG Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059 ChinaSearch for more papers by this authorKang CHEN, Kang CHEN Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059 ChinaSearch for more papers by this authorYao LIU, Yao LIU College of Earth Sciences, Chengdu University of Technology, Chengdu 610059 Sichuan, ChinaSearch for more papers by this authorXuyuan HAN, Xuyuan HAN College of Earth Sciences, Chengdu University of Technology, Chengdu 610059 Sichuan, ChinaSearch for more papers by this author First published: 29 December 2014 https://doi.org/10.1111/1755-6724.12380_48Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume88, Issues2Special Issue: Meeting Abstracts: The 14th Quadrennial International Association on the Genesis of Ore Deposits Symposium. August 19–22, 2014, Kunming, ChinaDecember 2014Pages 1319-1320 RelatedInformation
Abstract. The paper presents an analysis by using the methods of Eddy field calculation mean and wavelet maxima to detect seismic anomalies within the outgoing longwave radiation (OLR) data based on time and space. The distinguishing feature of the method of Eddy field calculation mean is that we can calculate "the total sum of the difference value" of "the measured value" between adjacent points, which could highlight the singularity within data. The identified singularities are further validated by wavelet maxima, which using wavelet transformations as data mining tools by computing the maxima that can be used to identify obvious anomalies within OLR data. The two methods has been applied to carry out a comparative analysis of OLR data associated with the earthquake recently occurred in Haiti on 12 January 2010. Combining with the tectonic explanation of spatial and temporal continuity of the abnormal phenomena, the analyzed results have indicated a number of singularities associated with the possible seismic anomalies of the earthquake and from the comparative experiments and analyses by using the two methods, which follow the same time and space, we conclude that the singularities observed from 19 to 24 December 2009 could be the earthquake precursor of Haiti earthquake.
The thermal deformation behavior of a novel CrFeNiSi0.15 medium entropy alloy (MEA) was studied in detail by means of isothermal compression experiments deformed under 900-1200ºC and 0.001-0.1s-1. According to experimental data, the modified Arrhenius-type constitutive equation was obtained, which could precisely predict the flow stress of CrFeNiSi0.15 MEA during thermal deformation. The hot activation energy (Q) of CrFeNiSi0.15 MEA was calculated to be about 417.270 kJ/mol. At the same time, the processing map of CrFeNiSi0.15 MEA were also carried out on the basis of dynamic material model (DMM) theory. In the thermal processing map of CrFeNiSi0.15 MEA, the peak efficiency of the CrFeNiSi0.15 MEA was about 39%, which occurred at the deformation parameter of 1200ºC/1s-1. Meanwhile, full dynamic recrystallization (DRX) occurred at such parameter. The flow instability of CrFeNiSi0.15 MEA was estimated to occur at 900-985°C/ 0.12-1s-1, which was shown as grain boundaries cracking. Furthermore, microstructure analysis suggested that the nucleation mechanism of continuous DRX (CDRX) as well as discontinuous DRX (DDRX) occurred simultaneously in thermal deformation, and CDRX was the dominant nucleation mechanism of DRX in high deformation temperature.
Abstract. This paper presents a validation and confutation analysis using the methods of the robust satellite data analysis technique (RST) to detect seismic anomalies within the bi-angular Advanced Along-Track Scanning Radiometer (AATSR) data based on spatial/temporal continuity analysis. The distinguishing feature of our method is that we carried out a comparative analysis of seismic anomalies from bi-directional observation, which could help understanding seismic thermal infrared (TIR) anomalies. The proposed method has been applied to analyse bi-angular AATSR gridded brightness temperature data with longitude from 5 to 25° E and latitude from 35 to 50° N associated with the earthquake that occurred in Abruzzo, Italy, on 6 April 2009, and a full data set of 7 yr data from 2003 to 2009 during the months of March and April has been analysed for validation purposes. Unperturbed periods (March–April 2008) have been considered for confutation analysis. Combining with the tectonic explanation of spatial and temporal continuity of the abnormal phenomena, along with the analysed results, a number of anomalies could be associated with possible seismic activities, which follow the same time and space. Therefore, we conclude that the anomalies observed from 29 March 2009 to 5 April 2009, about eight days before the Abruzzo earthquake, could be earthquake anomalies.
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