A distributed drift-flux model and a low-order lumped model describing a multiphase (gas-liquid) flow in the well during Under-Balanced Drilling (UBD) has been presented. This paper presents a novel nonlinear adaptive observer to estimate the total mass of gas and liquid in the annulus and production constant of gas and liquid from the reservoir into the well during UBD operations. Furthermore,...

Active noise and vibration control (ANC) has become an important application area for adaptive filters. The most popular adaptive algorithm used for ANC is the Filtered-X LMS (FXLMS) algorithm [1,2]. This algorithm is a modification of the well known LMS algorithm. The reference signal is filtered so as to compensate for filters inherent in the electro-acoustic adaptation loop. These additional...

In most petroleum and geoscience studies, the flow is controlled by the connectivity of extreme permeabilities (both high and low) associated with multiple-scale geological patterns. Hence, it is critical to model such patterns in order to predict successfully the flow performance. The new multiple-point geostatistical algorithm (FILTERSIM), which can handle both categorical and continuous vari...

Mohamad El Gharamti†, Ibrahim Hoteit, Johan Valstar †PhD, King Abdullah University of Science and Technology, Earth Sciences and Engineering, Thuwal 23955-6900 Saudi Arabia ?Assistant Professor, King Abdullah University of Science and Technology, Applied Mathematics and Computational Science, Thuwal 23955-6900 Saudi Arabia Geohydrologist, Deltares, Subsurface and groundwater systems, Utrecht, N...

By splitting the real line into intervals of unit length a doubly infinite integral of the form ∫∞ −∞ F (qx) dx, 0 < q < 1, can clearly be expressed as ∫ 1 0 ∑∞ n=−∞ F (q x+n) dx, provided F satisfies the appropriate conditions. This simple idea is used to prove Ramanujan’s integral analogues of his 1ψ1 sum and give a new proof of Askey and Roy’s extention of it. Integral analogues of the well-...

This paper investigates empirically how similarity of demand structures – approximated by similarity of income distributions – affects trade patterns along both the extensive and intensive margin. The idea that similarity of demand structures intensifies trade goes back to the well-known Linder hypothesis. Based on a sample of 102 countries, I find that bilateral trade volumes are increasing in...

When using Bai’s method for estimating the coefficients of both the linear and nonlinear parts of a Hammerstein model, there is no guarantee that the resulting linear filter will be stable. To obtain a stable linear filter the well-known minimum phase correction can be used. However, if it used without some compensation in the nonlinear part, one obtains a Hammerstein model with no theoretical ...

This paper presents the developement of a novel, fullyautomatic tracking and segmentation system to extract the boundary of the carotid artery from ultrasound images in real-time. The center of the carotid artery is tracked by using the Star algorithm [3]. The stability of the Star algorithm has been improved by using a temporal Kalman filter. A spatial Kalman filter is used to estimate the car...

Block-based physical modeling is a methodology for modeling physical systems with different subsystems. Each subsystem may be modeled according to a different paradigm. Connecting systems of diverse nature in the discrete-time domain requires a unified interconnection strategy. Such a strategy is provided by the well-known wave digital principle, which had been introduced initially for the desi...

SAR images are severely degraded by speckle, and filtering is therefore a common practice. Filtering is especially useful before compression, to avoid spending valuable resources to represent noise; unfortunately, it also degrades important image features, like region boundaries. To overcome this problem, one can resort to a segmentation-based compression scheme, which allows one to preserve re...