Papers by Keyword: FAST

Abstract: In this work, a commercially pure titanium powder has been consolidated using the Electrical Resistance Sintering (ERS) process. This technique consists in the consolidation of a powder mass by the simultaneous application of pressure (80 MPa, in this work) and heating caused by the passage of a high intensity (3.5-6.0 kA, in this case) and low voltage current (lower than 10 V), during short dwelling times (0.8-1.6 s, in this work). The resulting compacts have been mechanically characterised by measuring their microhardness distribution. The results obtained are compared with the corresponding values of compacts prepared with the same powders following the conventional P/M route of cold pressing and furnace sintering. The results of some simulations are provided to give information about the temperatures reached inside the compacts during the electrical consolidation process.

Abstract: FAST (Fast light Alloys Stamping Technology) has recently been developed to efficiently and economically manufacture lightweight, high strength structural components from aluminium alloys sheet. Post-form strength prediction of 6xxx series aluminium alloy (AA6xxx) after FAST and multiple stage heat treatments has been a challenge. This is due to the effect of pre-existing dislocations induced via high temperature plastic deformation in the forming process. In the present research, a new PFS (post-form strength) model has been proposed to predict the age-hardening response of AA6xxx alloys undergoing FAST and subsequent thermal cycles. The model incorporates two sub-models, for simulating viscoplastic flow and predicting strength evolution respectively. The first sub-model incorporates a set of constitutive equations, developed to model the stress-strain curve of AA6xxx during FAST. The second sub-model employs precipitation-hardening and dislocation-hardening theories to simulate the evolution of microstructure and, as a consequence, strength of alloys undergoing artificial ageing cycles. This is calculated by considering the intrinsic resistance of the alloy to dislocation movement due to solute atoms and precipitates. The strength was computed accurately via the internal state variables method, in which dislocation density, volume fraction of precipitates, solute concentration and radii of precipitates were correlated. Furthermore, the model was validated by comparing results with transmission electron microscope (TEM) images as well as hardness measurements. Hence, the model performs as a powerful and comprehensive tool to simulate post-form strength of 6xxx series aluminium alloys that undergo complicated thermomechanical processes including high temperature deformation and post-form heat treatment, with less than 5% deviation between measured and predicted values.

Abstract: Since FAST/SPS technology ensures an adequate and fast consolidation of different materials the demand for suitable pressing tool materials is growing. Graphite based materials are widely used and well known as FAST/SPS tool materials but they also have some unwanted or weak properties, for example, a possible reaction or reduction of sample material as well as low mechanical values compared to other tool materials. In this paper, an approach for the FAST/SPS consolidation of ZTA-Ti (C,N) and TiN-TiB₂ based cutting tool inserts in newly developed FAST/SPS tool materials which can be used for fully automated FAST2 devices is presented. Furthermore, a general strategy for the further development of FAST/SPS tool materials is focused.

Abstract: Development of on-site fast detector using for waterproof membrane joint peeling strength has improved the waterproof membrane on-site construction quality evaluation level and construction quality decision capability. Detectors capabilities in two-dimensional movement and multi-angle detection fill the domestic gap. Verification test result of the detector shows that, the peeling force will fluctuate within certain scope with peeling of joints; the longer the membrane is stretched, the greater the error is; the error caused by angle deviation is about 7% and error caused by joint deviation is about 4%, and the test result satisfies the evaluation requirement on waterproof membrane joint peeling strength at construction site. The development of detector improves the construction quality, construction management and acceptance of waterproof membrane.

Abstract: Due to the promotion of modern design feature, the placement solution is becoming more and more difficult to route. Previous routability-driven based technology is usually coupled with the original placer, which is difficult to be widely used in various placement tools. In this paper, we proposed a tool called CRT (Congestion Refinement Technique), which is independent of any placer and any router, and can be applied to various placemen to improve the routability. CRT is a congestion-driven based module shifting technique. Basically, CRT is one kind of technology that better allocating routing resources by shifting the modules. The boundary of tile is shifted in the horizontal and vertical directions without affecting the original placement. Here a longest path solution is presented to solve the problem fast and effectively. The experimental results show that the CRT can effectively alleviate the congestion of unroutable placement solutions. We apply it to placement solutions generated by placers on ISPD2011 [ placement benchmarks. From the result we can see that CRT greatly improves the routbility and saves execution time for the routing stage after refinement.

Abstract: According to the characteristics of Chinese characters image, we propose an improved corner detection method based on FAST algorithm and Harris algorithm to improve detection rate and shorten the running time for next feature extraction in this paper. The image of Chinese characters is detected for corners using FAST algorithm Firstly. Second, computing corner response function (CRF) of Harris algorithm, false corners are removed. The corners founded lastly are the endpoints of line segments, providing the length of line segments for shape feature extraction. The proposed method is compared with several corner detection methods over a number of images. Experimental results show that the proposed method shows better performance in terms of detection rate and running time.

Abstract: This paper proposes a fast query tree-based (FQT) algorithm for anti-collision in RFID system. Tags to be identified would be grouped by a reader randomly at beginning, and the reader identifies a group of tags and records the quantity of tags. Then reckons the number of all tags and carries out optimized group again. In identification process, the prefix of queries would add two bits in odd rounds, and one bit in even rounds. The results of analysis and simulation show that FQT algorithm can obtain the better performance than QT algorithm.

Abstract: Sensitivity analysis of bioretention cell design elements can provide a theoretical basis for the design and construction of a bioretention cell. This study uses the storm management model (SWMM) and the bioretention infiltration RECARGA to generate runoff and outflow time series for calculation of hydrologic performance metrics. The hydrologic performance metrics include: the overflow ratio, groundwater recharge ratio, ponding time and underdrain flow ratio. The FAST method is chose to analyze sensitivity of design elements for two types of bioretention cell, one without underdrain and the other with underdrain. The results show that the surface area is the most sensitivity to most the hydrologic metrics for both types of bioretention, while the planting soil depth and the gravel depth are the two least sensitive elements. The saturated infiltration rates of planting soil and native soil are another two sensitive elements for bioretention cells without underdrain, but the saturated infiltration rate of planting soil and underdrain size are another two sensitive design elements for bioretention cells with underdrain.Keywords: Global sensitivity analysis; bioretention cell; design elements; FAST

Abstract: FAST (Five-hundred-meter Aperture Spherical Telescope) will become the largest single dish ever built in the world. The feasibility of FAST concept, including observatory location, active reflector and feed support has been proven by theoretical analysis and experiments. Results of study indicate that this project is ready to move on to preliminary design. In order to verify the design idea and the key technologies of FAST, the 5-meter experiment model, the 50-m experiment mode and the active reflector model have been designed and constructed. The experiment shows that the feasibility of FAST is been proven by theoretical analysis and experiments.

Abstract: Human detection is a challenging problem, owing to variations in pose, body shape, appearance, clothing, illumination, and background clutter, in addition, the cameras or backgrounds make it even harder. But even so, it has many potential applications including net-meeting, security, human-computer interaction, gaming, and even health-care. Various new approaches have been proposed to solve this problem. We have studied and implemented a method by using dynamic contour [ and Histograms of Oriented Gradients [ to detecting human body fast and accurately in static images.