Tracking control for directional drilling systems using robust feedback model predictive control

A rotary steerable system (RSS) is a drilling technology which has been extensively studied and used for over the last 20 years in hydrocarbon exploration and it is expected to drill complex curved borehole trajectories. RSSs are commonly treated as dynamic robotic actuator systems, driven by a reference signal and typically controlled by using a feedback loop control law. However, due to spatial delays, parametric uncertainties and the presence of disturbances in such an unpredictable working environment, designing such control laws is not a straightforward process. Furthermore, due to their inherent delayed feedback, described by delay differential equations (DDE), directional drilling systems have the potential to become unstable given the requisite conditions. This paper proposes a Robust Model Predictive Control (RMPC) scheme for industrial directional drilling, which incorporates a simplified model described by ordinary differential equations (ODE), taking into account disturbances and system uncertainties which arise from design approximations within the formulation of RMPC. The stability and computational efficiency of the scheme are improved by a state feedback strategy computed offline using Robust Positive Invariant (RPI) sets control approach and model reduction techniques. A crucial advantage of the proposed control scheme is that it computes an optimal control input considering physical and designer constraints. The control strategy is applied in an industrial directional drilling configuration represented by a DDE model and its performance is illustrated by simulations

Composing Pieces for Peace: Using Impromptu to Build Cross-Cultural Awareness

Music has long played a role as an ambassador for peace and understanding between cultures. Yet, there is little research that gauges how creating music aids in the development of cross-cultural awareness. Given today’s tense political climate post-9/11, further investigation of the role that music can play in fostering cross-cultural awareness is needed. Using a sociocultural constructionist framework, this study investigated how 22 youth (12 girls and 10 boys) from the United States, in communication with youth in Tel-Aviv, Israel, analyzed and composed music steeped in traditional Hebrew, Arabic, and Western traditions using the computer program, Impromptu. Participants took part in pre-tests and post-tests to measure their awareness and respect for Israelis at the start and end of the study using the Cross-Cultural Awareness Drawing Task (Bar-Tal & Teichman, 2005). Using qualitative techniques, the researchers analyzed the written reflections of participants on their music composition process over the course of the intervention. Findings suggest that the music composition and analysis exercises had a positive impact on the development of crosscultural awareness over time among American students, helping to counter the common misconceptions about the Middle East fostered in today’s media

Generalist Primary School Teachers’ Preferences for Becoming Subject Matter Specialists

Traditionally Australian primary school teachers have been viewed as generalists responsible for instruction across all content areas. Adopting self-determination theory as a lens, the aim of the study was to explore the extent to which generalist primary school teachers are interested in becoming subject matter specialists. Questionnaire data were collected from 104 early years primary school teachers. Findings suggest that two-thirds of these generalist teachers expressed an interest in specialising in either English, mathematics, and to a far lesser extent, science, such that they would be responsible for exclusively teaching this subject. Preferences for specialisation were based on teachers’ self-perceived content and pedagogical expertise and/ or their enjoyment of teaching in this content area. By contrast, the one-third of teachers who would choose to remain generalists referred to the value in a variety of teaching experiences, teaching from a whole child perspective and content integration. Implications for educational policy are discussed

Text Line Segmentation of Historical Documents: a Survey

There is a huge amount of historical documents in libraries and in various National Archives that have not been exploited electronically. Although automatic reading of complete pages remains, in most cases, a long-term objective, tasks such as word spotting, text/image alignment, authentication and extraction of specific fields are in use today. For all these tasks, a major step is document segmentation into text lines. Because of the low quality and the complexity of these documents (background noise, artifacts due to aging, interfering lines),automatic text line segmentation remains an open research field. The objective of this paper is to present a survey of existing methods, developed during the last decade, and dedicated to documents of historical interest.Comment: 25 pages, submitted version, To appear in International Journal on Document Analysis and Recognition, On line version available at http://www.springerlink.com/content/k2813176280456k3

Photorespiration: metabolic pathways and their role in stress protection

Photorespiration results from the oxygenase reaction catalysed by ribulose-1,5-bisphosphate carboxylase/ oxygenase. In this reaction glycollate-2-phosphate is produced and subsequently metabolized in the photorespiratory pathway to form the Calvin cycle intermediate glycerate-3-phosphate. During this metabolic process, CO2 and NH3 are produced and ATP and reducing equivalents are consumed, thus making photorespiration a wasteful process. However, precisely because of this ine¤ciency, photorespiration could serve as an energy sink preventing the overreduction of the photosynthetic electron transport chain and photoinhibition, especially under stress conditions that lead to reduced rates of photosynthetic CO2 assimilation. Furthermore, photorespiration provides metabolites for other metabolic processes, e.g. glycine for the synthesis of glutathione, which is also involved in stress protection. In this review, we describe the use of photorespiratory mutants to study the control and regulation of photorespiratory pathways. In addition, we discuss the possible role of photorespiration under stress conditions, such as drought, high salt concentrations and high light intensities encountered by alpine plants

Time to Treat: A System Redesign Focusing on Decreasing the Time from Suspicion of Lung Cancer to Diagnosis

IntroductionMultiple investigations often result in a lengthy process from the onset of lung cancer–related symptoms until diagnosis. An unpublished chart audit indicated suboptimal delays in patients' courses from onset of symptoms until diagnosis of cancer.MethodsThe Time to Treat Program was designed for patients with clinical or radiographic suspicion of lung cancer. Pre- and postimplementation data on median wait times were compared.ResultsFrom April 2005 to January 2007, 430 patients were referred. After Time to Treat Program implementation, the median time from suspicion of lung cancer to referral for specialist consultation decreased from 20 days to 6 days, and the median time from such referral to the actual consultation date decreased from 17 days to 4 days. The median time from specialist consultation to computed tomography scan decreased from 52 days to 3 days, and the median time from computed tomography scan to diagnosis decreased from 39 days to 6 days. Overall, the median time from suspicion of lung cancer to diagnosis decreased from 128 days to 20 days. Of all patients in the Time to Treat Program, 33% were eventually diagnosed with lung cancer.ConclusionsTime to Treat Program was effective in shortening the time from suspicion of lung cancer to diagnosis and reduced time intervals at each step in the process. Earlier diagnosis of lung cancer may allow increased treatment options for patients and may improve outcomes

Nuclear receptor REVERBα is a state-dependent regulator of liver energy metabolism

The nuclear receptor REVERBα is a core component of the circadian clock and proposed to be a dominant regulator of hepatic lipid metabolism. Using antibody-independent ChIP-sequencing of REVERBα in mouse liver, we reveal a high-confidence cistrome and define direct target genes. REVERBα-binding sites are highly enriched for consensus RORE or RevDR2 motifs and overlap with corepressor complex binding. We find no evidence for transcription factor tethering and DNA-binding domain-independent action. Moreover, hepatocyte-specific deletion of Reverbα drives only modest physiological and transcriptional dysregulation, with derepressed target gene enrichment limited to circadian processes. Thus, contrary to previous reports, hepatic REVERBα does not repress lipogenesis under basal conditions. REVERBα control of a more extensive transcriptional program is only revealed under conditions of metabolic perturbation (including mistimed feeding, which is a feature of the global Reverbα -/- mouse). Repressive action of REVERBα in the liver therefore serves to buffer against metabolic challenge, rather than drive basal rhythmicity in metabolic activity

Temperature regulates NF-κB dynamics and function through timing of A20 transcription

NF-κB signaling plays a pivotal role in control of the inflammatory response. We investigated how the dynamics and function of NF-κB were affected by temperature within the mammalian physiological range (34 °C to 40 °C). An increase in temperature led to an increase in NF-κB nuclear/cytoplasmic oscillation frequency following Tumor Necrosis Factor alpha (TNFα) stimulation. Mathematical modeling suggested that this temperature sensitivity might be due to an A20-dependent mechanism, and A20 silencing removed the sensitivity to increased temperature. The timing of the early response of a key set of NF-κB target genes showed strong temperature dependence. The cytokine-induced expression of many (but not all) later genes was insensitive to temperature change (suggesting that they might be functionally temperature-compensated). Moreover, a set of temperature- and TNFα-regulated genes were implicated in NF-κB cross-talk with key cell-fate–controlling pathways. In conclusion, NF-κB dynamics and target gene expression are modulated by temperature and can accurately transmit multidimensional information to control inflammation