1,721,986 research outputs found
Results of a gibbon survey in the Kim Hy Nature Reserve (Bac Kan province) in northeastern Vietnam
Full text linkThe cao-vit crested gibbon (Nomascus nasutus) is one of the world’s most endangered primate species, with one single protected forest patch in the border area between Cao Bang province (Vietnam) and Guangxi province (China) supporting the last known population. No other locality is known to support a population of this species, however, some gibbons are rumoured to have survived in Kim Hy Nature Reserve of Bac Kan province (northeastern Vietnam). Although several previous surveys in Kim Hy failed to find direct evidence for the continued occurrence of gibbons there, each provided interview information indicating that Kim Hy still supported a few gibbons. In order to resolve the contradiction, we conducted a two-week survey in Kim Hy in June 2009. We recorded intrusion of agriculture in the periphery of the nature reserve, massive logging going on mostly, but not exclusively, in the periphery of the reserve, and hunting and gold mining in all areas including the corezone of the reserve
ANALYSIS OF BEAM LANDING SHIFTS DUE TO THERMAL DEFORMATIONS OF A SHADOW MASK
No full textFinite element analysis is performed for the purpose of calculating the landing shift of electron beams due to thermal deformations of a shadow mask. For realistic finite element analysis, firstly the apparent thermal conductivity and the apparent elastic modulus are calculated, and the shadow mask is modeled as shell without slits. Next the finite element formulation is developed for transient thermo-elastic deformation of the shadow mask, wherein thermal radiation is a major heat transfer mechanism. The simulation results are in good agreement with the test results, and this suggests that the present finite element scheme may be efficiently used for thermal deformation design of a shadow mask
Hierarchical random graph representation of handwritten characters and its application to Hangul recognition
No full textA hierarchical random graph (HRG) representation for handwritten character modeling is presented. Based on the HRG, a Hangul, Korean scripts, recognition system also has been developed. In the HRG, the bottom layer is constructed with extended random graphs to describe various strokes, while the next upper layers are constructed with random graphs (Wong and Ghahraman, IEEE Trans. Pattern Anal. Mach. Intell. 2(4) (1980) 341) to model spatial and structural relationships between strokes and between sub-characters. As the proposed HRG is a stochastic model, the recognition is formulated into the problem that chooses a model producing maximum probability given an input data. In this context, a matching score is acquired not by any heuristic similarity function, but by a probabilistic measure. The recognition process starts from converting an input character image into an attributed graph through the preprocessing and the graph representation. Matching between an attributed graph and the hierarchical graph model is performed bottom-up. Since the hierarchical structure in an attributed graph is decided after the recognition ends depending on the best interpretation of the graph matching, we can avoid incorrect sub-character segmentation. Model parameters of the hierarchical graph have been estimated automatically from the training data by EM algorithm (Dempster et al., J. Roy. Stat. Soc. 39 (1977) 1) and embedded training. The recognition experiments conducted with unconstrained handwritten Hangul characters show the usefulness and the effectiveness of the proposed HRG. (C) 2000 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved
Effect of microstructure on the high-temperature deformation behavior of Ti-48Al-2W intermetallic compounds
No full textThe effect of microstructure on high-temperature deformation behavior of Ti-48Al-2W intermetallic compounds has been investigated in compressive tests performed at 1100 and 1200 degrees C. The microstructures were controlled as near gamma, duplex and near lamellar structure by heat treatments of cast ingots at 1250, 1300 and 1350 degrees C, respectively. The stress-strain curve exhibits a peak stress, which is followed by a gradual decrease into a steady state with increasing the strain. The peak flow stress was the highest in the near lamellar structure. The flow softening rate is higher in the near lamellar structure than that in the near gamma structure. The flow softening behavior of near gamma Ti-48Al-2W was due to a dynamic recrystallization of gamma grains. The flow softening behavior in near lamellar Ti-48Al-2W was occurred by kinking, rotating and globularization of lamellars. The flow localization and shear bands were observed in near lamellar structure during the high-temperature deformation. The flow localization parameters were calculated from the analysis based on the instability condition. The flow localization in the near lamellar structure was due to a higher flow softening rate. (C) 1999 Published by Elsevier Science S.A. All rights reserved
HIGH-TEMPERATURE DEFORMATION-BEHAVIOR OF 20 VOL-PERCENT SICW/2024AL METAL-MATRIX COMPOSITE
No full textTrace-driven performance simulation modeling for fast evaluation of multimedia processor by simulation reuse
No full textA method for fast but yet accurate performance evaluation of processor architecture is mostly desirable in modern processors design. This paper proposes one such method which can measure cycle counts. and power consumption of pipelined processors. The method first develops a trace-driven performance simulation model and then employs simulation reuse in simulation of the model. The trace-driven performance modeling is for accuracy in which performance simulation uses the same execution traces as constructed in simulation for functional verification. Fast performance simulation can be achieved in a way that performance for each instruction in the traces is evaluated without evaluation of the instruction itself. Simulation reuse supports simulation speedup by elimination of an evaluation at the current state, which is identical to that at a previous state. The reuse approach is based on the property that application programs, especially multimedia applications, have many iterative loops in general. A performance simulator for pipeline architecture based on the proposed method has been developed through which greater speedup has been made compared with other approaches in performance evaluation
High temperature deformation behavior and microstructural evolution of Ti-47Al-2Cr-4Nb intermetallic alloys
No full textDesign and control of active magnetic bearing system with Lorentz force-type axial actuator
No full textAs the size of five-axes active magnetic bearing (AMB) system gets smaller, the space limitation for installation of axial magnetic bearing unit and the eddy current induced braking of radial magnetic bearing unit become a stringent design concern. In this paper, a new type of compact, high-performance five-axes AMB with solid cores and rotor is proposed, which consists of four permanent magnets, four U-shaped cores and 16 control coils. It features that the radial and axial magnetic bearing units are integrated for compact design and that the homo-polar type configuration of poles with optimized pitch length is adopted to minimize the eddy current induced braking force. The proposed homo-polar AMB system is levitated by the Lorentz-type axial as well as Maxwell-type radial forces. Based on the magnetic flux distribution analysis, the control algorithm is designed to account for the coupled effect between the radial and axial control fluxes. Experiments are also carried out with a prototype AMB system to validate the new design concept. (C) 2005 Elsevier Ltd. All rights reserved
The effect of microstructures on creep behavior of Ti-48Al-2W intermetallic compounds
No full textThe creep behaviors of Ti-48Al-2W intermetallic compounds have been investigated by constant stress tests at the temperature range of 750-850degreesC under the stress range of 170-440 MPa. The effects of lamellar grain size and lamellar volume fraction on the creep behavior of Ti-48Al-2W compounds were analyzed. The minimum creep rate was almost independent on the lamellar grain size in the range of 135-400 mum, while the minimum creep rate was sensitively dependent on the lamellar volume fraction. The minimum creep rate decreased with increasing the lamellar volume fraction in the range of 70-100%. The activation energies were measured as 298 kJ mol(-1) for the near gamma structure, 340 kJ mol(-1) for the near lamellar structure and 345 kJ mol(-1) for the fully lamellar structure. The stress exponents were measured as 6.4 in the near gamma structure, 4.9 in the fully lamellar structure and 5.0-5.5 in the near lamellar structure having the lamellar volume fraction of 70-95%. The dislocation structures in the crept specimen were analyzed. The creep rates of near lamellar structure were analyzed by the rule-of-mixtures from the creep rates of fully lamellar structure and near gamma structure. (C) 2002 Elsevier Science B.V. All rights reserved
- …
