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101.
Minh-Tuan Pham Laurent Briançon Daniel Dias Abdelkader Abdelouhab 《Geotextiles and Geomembranes》2018,46(5):611-624
Geosynthetic-reinforced soils constitute an interesting solution for bridging cavities. Many methods have been developed to analyze the stability of soil-geosynthetic-cavity systems, but none of them is able to take into account all the complexities of these mechanisms. Many researchers have assumed mechanisms developed in the reinforced granular platform when cavities appear, such as load transfer and expansion of materials. However, they are not fully understood because many factors can influence the design, such as the cavity opening processes, the type, and the density of the soil.In this study, a new laboratory apparatus is developed to simulate two different cavity opening procedures (trapdoor and progressive opening) for different geometric configurations. A series of tests is conducted for three granular soils with two different geosynthetic sheets. By measuring the shape of the surface soil settlement and the geosynthetic deflection, the expansion coefficient is calculated. A novel tactile pressure sensor is used to observe the load transfer during the cavity opening. The experimental data are analyzed and the influence of the experimental conditions (geometric and soil properties and the opening procedure) are also discussed. Correspondingly, elicited findings can be used to propose recommendations to improve the existing design methods. 相似文献
102.
Wireless Personal Communications - Cognitive radio networks (CRNs) have a shortcoming in that attackers can increase their ability to disturb secondary users (SUs). This paper focuses on jamming... 相似文献
103.
This paper proposes the hybrid model of autoregressive moving average (ARMA) and generalized autoregressive conditional heteroscedasticity (GARCH) to estimate and forecast the machine state based on vibration signal. The main idea in this study is to employ the linear ARMA model and the nonlinear GARCH model to explain the wear and fault condition of machine, respectively. The successful outcomes of the ARMA/GARCH prediction model can give obvious explanation for future states of machine, which enhance the worth of machine condition monitoring as well as condition-based maintenance in practical applications. The advance of the proposed model is verified in empirical results as applying for a real system of a methane compressor in a petrochemical plant. 相似文献
104.
Greenhouse gas emission mitigation potential of rice husks for An Giang province, Vietnam 总被引:1,自引:0,他引:1
To evaluate the greenhouse gas (GHG) emission mitigation potential of rice husk utilization, a life cycle inventory analysis was conducted for 18 scenarios. The allocation of fuels, other than rice husks, was decided based on the current demand for and supply of rice husks. To prevent the bulky nature of rice husks, briquette production is also discussed. In the power generation scenarios, the differences between two capacities (5 MW and 30 MW) were analyzed. The results of analysis reveal that CH4 and N2O emissions from open burning contribute largely to the current GHG emissions. Therefore, ceasing open burning alone has a large GHG mitigation potential. The use of briquettes, even though GHG is emitted during the production stage, can still contribute to GHG emission mitigation as the production is more efficient than rice husk burning or dumping. In the power generation scenarios, most GHG emissions were derived from the combustion process. Therefore, gasification which has a little combustion process is the most efficient GHG mitigator. Both the replacement of grid electricity by generated electricity, and the replacement of diesel oil by pyrolyzed oil show larger GHG mitigation potentials than what could be derived from open burning cessation alone. 相似文献
105.
We are given a trajectory
T\mathcal{T}
and an area
A\mathcal{A}
.
T\mathcal{T}
might intersect
A\mathcal{A}
several times, and our aim is to detect whether
T\mathcal{T}
visits
A\mathcal{A}
with some regularity, e.g. what is the longest time span that a GPS-GSM equipped elephant visited a specific lake on a daily
(weekly or yearly) basis, where the elephant has to visit the lake most of the days (weeks or years), but not necessarily on every day (week or year). 相似文献
106.
Duy Nguyen David Halupka Parham Aarabi Ali Sheikholeslami 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(4):902-912
This paper proposes a new technique for face detection and lip feature extraction. A real-time field-programmable gate array (FPGA) implementation of the two proposed techniques is also presented. Face detection is based on a naive Bayes classifier that classifies an edge-extracted representation of an image. Using edge representation significantly reduces the model's size to only 5184 B, which is 2417 times smaller than a comparable statistical modeling technique, while achieving an 86.6% correct detection rate under various lighting conditions. Lip feature extraction uses the contrast around the lip contour to extract the height and width of the mouth, metrics that are useful for speech filtering. The proposed FPGA system occupies only 15050 logic cells, or about six times less than a current comparable FPGA face detection system. 相似文献
107.
This article analyzes the dynamics of motion of various setups of two multiple degree‐of‐freedom (DOF) fingers that have soft tips, in fine manipulation of an object, and shows performances of their motions via computer simulation. A mathematical model of these dynamics is described as a system of nonlinear differential equations expressing motion of the overall fingers‐object system together with algebraic constraints due to tight area contacts between the finger‐tips and surfaces of the object. First, problems of (1) dynamic, stable grasping and (2) regulation of the object rotational angle by means of a setup of dual two‐DOF fingers, are treated. Second, the problem of regulating the position of the object mass center by means of a pair of two‐DOF and three‐DOF fingers is considered. Third, a set of dual three‐DOF fingers is treated, in order to let it perform a sophisticated task, which is specified by a periodic pattern of the object posture and a constant internal force. In any case, there exist sensory‐motor coordinations, which are described by analytic feedback connections from sensing to actions at finger joints. In the cases of setpoint control problems, convergences of motion to secure grasping together with the specified object rotational angle and/or the specified object mass center position, are proved theoretically. A constraint stabilization method (CSM) is used for solving numerically the differential algebraic equations to show performances of the proposed sensory‐feedback schemes. © 2002 Wiley Periodicals, Inc. 相似文献
108.
109.
Dinh Tuan Pham 《Signal Processing, IEEE Transactions on》1996,44(11):2768-2779
In this paper, we introduce a procedure for separating a multivariate distribution into nearly independent components based on minimizing a criterion defined in terms of the Kullback-Leibner distance. By replacing the unknown density with a kernel estimate, we derive useful forms of this criterion when only a sample from that distribution is available. We also compute the gradient and Hessian of our criteria for use in an iterative minimization. Setting this gradient to zero yields a set of separating functions similar to the ones considered in the source separation problem, except that here, these functions are adapted to the observed data. Finally, some simulations are given, illustrating the good performance of the method 相似文献
110.
Nanometre-sized silver halides entrapped in SiO2 matrices 总被引:2,自引:0,他引:2
The formation of nanocrystals after implantation of silver alone as well as together with the halogen ions Cl, Br and I into a SiO2 layer of about 100 nm was studied by X-ray diffraction and transmission electron microscopy. The co-implantation of Ag and Cl or Br results in the formation of cubic AgX crystals which are stable in size under annealing. The co-implantation of Ag and I as well as single Ag implantation result in Ag crystallites, which grow under annealing. The annealing procedure causes a redistribution of the particles within the layer. 相似文献