Entity

Time filter

Source Type

TX, United States

Mohan K.,Pioneer Natural Resources Inc. | Adil F.,Halliburton Co. | Samuel R.,Houston TX
Journal of Energy Resources Technology, Transactions of the ASME | Year: 2015

Over the last few years, different types of bits have been introduced to meet the challenges of steerable as well as rotary steerable systems; and it is imperative that bits be utilized optimally in these systems. As challenges increase with increasing depths, it becomes even more important for one to efficiently utilize the available energy (Robello, S., 2013, Modeling and Analysis of Drillstring Vibration in Riserless Environment, ASME J. Energy Res. Technol., 135(1), p. 013101). A new correlation identifying inefficient drilling conditions is presented in this paper. Mechanical specific energy (MSE) has been used to improve drilling rates, with mixed results. Hydro MSE (HMSE), which is introduced here, encompasses hydraulic as well as mechanical energy. HMSE quantifies the amount of energy required to drill a unit volume of rock and remove it from underneath the bit. HMSE includes axial, torsional, and hydraulic energy and is different from MSE because it includes a hydraulic term. The initial MSE correlation (Teale, R., 1965, The Concept of Specific Energy in Rock Drilling,Int. J. Rock Mech. Min. Sci., 2, pp. 57-73.) was modified to accommodate the new hydraulic term. This paper attempts to better model downhole drilling by introducing the hydraulic energy term in the MSE correlation by defining it as HMSE. While the majority of the drilling occurs because of the bit, it is a well-known fact that some drilling occurs due to the jet impact impingement caused by the drilling fluid as well. Experimental and field data presented in this paper show that HMSE can identify inefficient drilling conditions. The new hydraulic term included in the specific energy correlation is the key to correctly match the amount of energy required to drill and overcome the strength and stresses of formation being drilled. Also, this new term illustrates how much hydraulic energy is needed to drill faster when the mechanical energy (axial and torsional) is increased. The results also show the importance of including the bit hydraulic energy term into any specific energy analysis for drilling optimization. Field results reveal specific patterns for inefficient drilling conditions and also reveal a good correlation between calculated HMSE and the expected requirements for rock removal under existent conditions of stress at the bit face (Mohan, K., and Robello Samuel, F. A., 2009, Tracking Drilling Efficiency Using Hydro-Mechanical Specific Energy,SPE/IADC Drilling Conference and Exhibition, March 17-19, Amsterdam, The Netherlands, No. SPE 119421). © 2014 by ASME . Source


Karmonik C.,Methodist Hospital | Fung S.H.,Houston TX | Dulay M.,Methodist Hospital | Verma A.,Methodist Hospital | Grossman R.G.,Methodist Hospital
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2013

Graph-theoretical analysis algorithms have been used for identifying subnetworks in the human brain during the Default Mode State. Here, these methods are expanded to determine the interaction of the sensory and the motor subnetworks during the performance of an approach-avoidance paradigm utilizing the correlation strength between the signal intensity time courses as measure of synchrony. From functional magnetic resonance imaging (fMRI) data of 9 healthy volunteers, two signal time courses, one from the primary visual cortex (sensory input) and one from the motor cortex (motor output) were identified and a correlation difference map was calculated. Graph networks were created from this map and visualized with spring-embedded layouts and 3D layouts in the original anatomical space. Functional clusters in these networks were identified with the MCODE clustering algorithm. Interactions between the sensory sub-network and the motor sub-network were quantified through the interaction strengths of these clusters. The percentages of interactions involving the visual cortex ranged from 85 % to 18 % and the motor cortex ranged from 40 % to 9 %. Other regions with high interactions were: frontal cortex (19 ± 18 %), insula (17 ± 22 %), cuneus (16 ± 15 %), supplementary motor area (SMA, 11 ± 18 %) and subcortical regions (11 ± 10 %). Interactions between motor cortex, SMA and visual cortex accounted for 12 %, between visual cortex and cuneus for 8 % and between motor cortex, SMA and cuneus for 6 % of all interactions. These quantitative findings are supported by the visual impressions from the 2D and 3D network layouts. © 2013 IEEE. Source


Roh J.-W.,University of Houston | Roh J.-W.,Dongguk University | Huang J.,University of Houston | Hu W.,University of Houston | And 20 more authors.
Clinical Cancer Research | Year: 2014

Purpose: Platelet-derived growth factor receptor a (PDGFRa) expression is frequently observed in many kinds of cancer and is a candidate for therapeutic targeting. This preclinical study evaluated the biologic significance of PDGFRa and PDGFRa blockade (using a fully humanized monoclonal antibody, 3G3) in uterine cancer. Experimental Design: Expression of PDGFRa was examined in uterine cancer clinical samples and cell lines, and biologic effects of PDGFRa inhibition were evaluated using in vitro (cell viability, apoptosis, and invasion) and in vivo (orthotopic) models of uterine cancer. Results: PDGFRa was highly expressed and activated in uterine cancer samples and cell lines. Treatment with 3G3 resulted in substantial inhibition of PDGFRa phosphorylation and of downstream signaling molecules AKT and mitogen-Activated protein kinase (MAPK). Cell viability and invasive potential of uterine cancer cells were also inhibited by 3G3 treatment. In orthotopic mouse models of uterine cancer, 3G3 monotherapy had significant antitumor effects in the PDGFRa-positive models (Hec-1A, Ishikawa, Spec-2) but not in the PDGFRa-negative model (OVCA432). Greater therapeutic effects were observed for 3G3 in combination with chemotherapy than for either drug alone in the PDGFRa-positive models. The antitumor effects of therapy were related to increased apoptosis and decreased proliferation and angiogenesis. Conclusions: These findings identify PDGFRa as an attractive target for therapeutic development in uterine cancer. Clin Cancer Res © 2014 American Association for Cancer Research. Source

Discover hidden collaborations