Control of sideslip and yaw rate in 4-wheel steering car using partial decoupling and individual channel design

This paper presents a new steering control structure for cars equipped with 4-wheel steering. This control structure is based on a simplified linear model of the lateral dynamics of such cars and aims to decouple the control of sideslip from the control of yaw rate. The control design is based on a linear multivariable plant which incorporates the model of the lateral dynamics mentioned above and whose inputs are linear combinations of the front and rear steering angles. The plant also contains a cross-feedback element. The matrix transfer function of the resulting plant is upper-triangular (partially decoupled). The MIMO design problem can then be recast as two SISO design problems using channel decomposition according to the Individual Channel Design (ICD) paradigm. The proposed control structure has been applied to design sideslip and yaw rate controllers using a more accurate model of the lateral dynamics of 4-wheel steering cars. This model incorporates the tyre force dynamics and the steering actuators. Simulations are used to illustrate the performance and robustness of the designed controllers

Gyrotorque transmission system for wind turbines

The GyroTorqueTM transmission system employs gyroscopic torque reaction to transmit power offering an alternative to the gearbox and electrical variable speed drive of a conventional wind turbine. The power transmission is fundamentally oscillatory and is rectified by mechanical elements. A precessing gyro maps speed to torque and, since the wind turbine rotor inertia strongly filters rotor speed variation, output power is insensitive to wind turbulence because it reflects wind turbine rotor speed variability rather than rotor torque variability. The GyroTorqueTM system has only bearing losses and potentially a high efficiency. Mechanical control of the input to the GyroTorqueTM system enables wide range variable speed operation of the wind turbine rotor using a conventional synchronous generator. At present, a 6 gyro system driven by an axial cam and connected to a conventional synchronous generator is the preferred system. Loads and power quality have been addressed with computer simulation models of the GyroTorqueTM system. Outline assessment of system mass and cost gives encouragement that it may be less than for conventional transmission systems

Innovative concepts for aerodynamic control of wind turbine rotors

New systems for the aerodynamic control of wind turbine rotors are being studied in various projects funded by the UK Department of Energy. Results from a current project, ongoing at the National Wind Turbine Test Centre (NWTC) in Scotland are presented. These systems show the promise of much cheaper and more affective active control of horizontal axis wind turbines than has been achieved with full span and partial span pitching systems

Supplementing wind turbine pitch control with a trailing edge flap smart rotor

Placement of additional control devices along the span of the wind turbine blades is being considered for multi-MW wind turbines to actively alter the local aerodynamic characteristics of the blades. This smart rotor approach can reduce loads on the rotor due to wind field non-uniformity, but also, as presented in this paper, can supplement the pitch control system. Rotor speed and tower vibration damping are actively controlled using pitch. By supplementing the speed control using smart rotor control, pitch actuator travel is reduced by 15 pitch rates by 23 and pitch accelerations by 42 This is achieved through filtering the pitch demand such that high frequency signals are dealt with by the smart rotor devices while the low frequency signal is dealt with by pitching the blades. It is also shown that this may be achieved while also using the smart rotor control for load reduction, though with reduced effectiveness. This shows that smart rotor control can be used to trade pitch actuator requirements as well as load reductions with the cost of installing and maintaining the distributed devices

Story and Illustration Reconstituted: Children's Literature in Canadian Reading Programs

This study addresses the differences between literature in children's trade books and the literature in commercial elementary language arts reading programs used in Canada. Although the nature of the literature included in language arts programs has received considerable scrutiny in the United States, there is no parallel body of research in the Canadian context. Using a textual content analysis, all the literature selections contained in the three most extensively used reading programs in Canada were where possible compared with the corresponding trade books. Numerous differences between trade book literature and the corresponding selections in the reading programs suggest that the two are not equivalent in the reading experiences they provide for children. The changes included alterations to format such as omissions, additions, substitutions, and reordering of text and illustrations. Many of the original selections reconstituted in the reading programs were impoverished by the changes. Further research is needed on how these changes alter children's reading experiences.Cette élude se penche sur les différences entre la littérature pour enfants dans les publications commerciales et celle que l'on retrouve dans les cours de langues et littérature pour les élèves de l'élémentaire au Canada. Alors qu'aux États-Unis, la nature de la littérature étudiée dans les cours de langue et littérature a fait l'objet d'examens détaillés, au Canada, aucune recherche comparable n'a été entreprise. En s'appuyant sur une analyse de contenu approfondie, nous avons, dans la mesure du possible, comparé toute la littérature étudiée au sein des trois programmes de lecture les plus populaires au Canada, aux textes correspondants dans les publications commerciales. Les nombreuses différences repérées entre les publications commerciales et les sélections correspondantes employées dans les programmes de lecture permettent de conclure que les deux ne fournissent pas élèves des expériences de lecture équivalentes. Parmi les écarts notons des changements de format tels des omissions, des ajouts, des substitutions et une réorganisation du texte et illustrations. Plusieurs des sélections originales qui avaient été reconstituées dans les programmes de lecture avaient été appauvries par les changements. Davantage d'études devraient porter sur la façon dont ces changements modifient l'expérience de lecture des enfants

Guidelines on the management of ascites in cirrhosis.

The British Society of Gastroenterology in collaboration with British Association for the Study of the Liver has prepared this document. The aim of this guideline is to review and summarise the evidence that guides clinical diagnosis and management of ascites in patients with cirrhosis. Substantial advances have been made in this area since the publication of the last guideline in 2007. These guidelines are based on a comprehensive literature search and comprise systematic reviews in the key areas, including the diagnostic tests, diuretic use, therapeutic paracentesis, use of albumin, transjugular intrahepatic portosystemic stent shunt, spontaneous bacterial peritonitis and beta-blockers in patients with ascites. Where recent systematic reviews and meta-analysis are available, these have been updated with additional studies. In addition, the results of prospective and retrospective studies, evidence obtained from expert committee reports and, in some instances, reports from case series have been included. Where possible, judgement has been made on the quality of information used to generate the guidelines and the specific recommendations have been made according to the 'Grading of Recommendations Assessment, Development and Evaluation (GRADE)' system. These guidelines are intended to inform practising clinicians, and it is expected that these guidelines will be revised in 3 years' time

Improving air quality model predictions of organic species using measurement-derived organic gaseous and particle emissions in a petrochemical-dominated region

This study assesses the impact of revised volatile organic compound (VOC) and organic aerosol (OA) emissions estimates in the GEM-MACH (Global Environmental Multiscale–Modelling Air Quality and CHemistry) chemical transport model (CTM) on air quality model predictions of organic species for the Athabasca oil sands (OS) region in Northern Alberta, Canada. The first emissions data set that was evaluated (base-case run) makes use of regulatory-reported VOC and particulate matter emissions data for the large oil sands mining facilities. The second emissions data set (sensitivity run) uses total facility emissions and speciation profiles derived from box-flight aircraft observations around specific facilities. Large increases in some VOC and OA emissions in the revised-emissions data set for four large oil sands mining facilities and decreases for others were found to improve the modeled VOC and OA concentration maxima in facility plumes, as shown with the 99th percentile statistic and illustrated by case studies. The results show that the VOC emission speciation profile from each oil sand facility is unique and different from standard petrochemical-refinery emission speciation profiles used for other regions in North America. A significant increase in the correlation coefficient is reported for the long-chain alkane predictions against observations when using the revised emissions based on aircraft observations. For some facilities, larger long-chain alkane emissions resulted in higher secondary organic aerosol (SOA) production, which improved OA predictions in those plumes. Overall, the use of the revised-emissions data resulted in an improvement of the model mean OA bias; however, a decrease in the OA correlation coefficient and a remaining negative bias suggests the need for further improvements to model OA emissions and formation processes. The weight of evidence suggests that the top-down emission estimation technique helps to better constrain the fugitive organic emissions in the oil sands region, which are a challenge to estimate given the size and complexity of the oil sands operations and the number of steps in the process chain from bitumen extraction to refined oil product. This work shows that the top-down emissions estimation technique may help to constrain bottom-up emission inventories in other industrial regions of the world with large sources of VOCs and OA.</p

Portal hypertension in polycystic liver disease patients does not affect wait-list or immediate post-liver transplantation outcomes

AIM: To establish the impact of portal hypertension (PH) on wait-list/post-transplant outcomes in patients with polycystic liver disease (PCLD) listed for liver transplantation. METHODS: A retrospective single-centre case controlled study of consecutive patients listed for liver transplantation over 12 years was performed from our centre. PH in the PCLD cohort was defined by the one or more of following parameters: (1) presence of radiological or endoscopic documented varices from our own centre or the referral centre; (2) splenomegaly (> 11 cm) on radiology in absence of splenic cysts accounting for increased imaging size; (3) thrombocytopenia (platelets < 150 × 10(9)/L); or (4) ascites without radiological evidence of hepatic venous outflow obstruction from a single cyst. RESULTS: Forty-seven PCLD patients (F: M = 42: 5) were listed for liver transplantation (LT) (single organ, n = 35; combined liver-kidney transplantation, n = 12) with 19 patients (40.4%) having PH. When comparing the PH group with non-PH group, the mean listing age (PH group, 50.6 (6.4); non-PH group, 47.1 (7.4) years; P = 0.101), median listing MELD (PH group, 12; non-PH group, 11; P = 0.422) median listing UKELD score (PH group, 48; non-PH group, 46; P = 0.344) and need for renal replacement therapy (P = 0.317) were similar. In the patients who underwent LT alone, there was no difference in the duration of ICU stay (PH, 3 d; non-PH, 2 d; P = 0.188), hospital stay length (PH, 9 d; non-PH, 10 d; P = 0.973), or frequency of renal replacement therapy (PH, 2/8; non-PH, 1/14; P = 0.121) in the immediate post-transplantation period. CONCLUSION: Clinically apparent portal hypertension in patients with PCLD listed for liver transplantation does not appear to have a major impact on wait-list or peri-transplant morbidity

British Society of Gastroenterology Best Practice Guidance: outpatient management of cirrhosis - part 3: special circumstances

\ua9 2023 BMJ Publishing Group. All rights reserved.The prevalence of cirrhosis has risen significantly over recent decades and is predicted to rise further. Widespread use of non-invasive testing means cirrhosis is increasingly diagnosed at an earlier stage. Despite this, there are significant variations in outcomes in patients with cirrhosis across the UK, and patients in areas with higher levels of deprivation are more likely to die from their liver disease. This three-part best practice guidance aims to address outpatient management of cirrhosis, in order to standardise care and to reduce the risk of progression, decompensation and mortality from liver disease. Part 1 addresses outpatient management of compensated cirrhosis: screening for hepatocellular cancer, varices and osteoporosis, vaccination and lifestyle measures. Part 2 concentrates on outpatient management of decompensated disease including management of ascites, encephalopathy, varices, nutrition as well as liver transplantation and palliative care. In this, the third part of the guidance, we focus on special circumstances encountered in managing people with cirrhosis, namely surgery, pregnancy, travel, managing bleeding risk for invasive procedures and portal vein thrombosis

British Society of Gastroenterology Best Practice Guidance: outpatient management of cirrhosis - part 1: compensated cirrhosis

\ua9 2023 BMJ Publishing Group. All rights reserved.The prevalence of cirrhosis has risen significantly over recent decades and is predicted to rise further. Widespread use of non-invasive testing means cirrhosis is increasingly diagnosed at an earlier stage. Despite this, there are significant variations in outcomes in patients with cirrhosis across the UK, and patients in areas with higher levels of deprivation are more likely to die from their liver disease. This three-part best practice guidance aims to address outpatient management of cirrhosis, in order to standardise care and to reduce the risk of progression, decompensation and mortality from liver disease. Here, in part one, we focus on outpatient management of compensated cirrhosis, encompassing hepatocellular cancer surveillance, screening for varices and osteoporosis, vaccination and lifestyle measures. We also introduce a compensated cirrhosis care bundle for use in the outpatient setting. Part two concentrates on outpatient management of decompensated disease including management of ascites, encephalopathy, varices, nutrition as well as liver transplantation and palliative care. The third part of the guidance covers special circumstances encountered in managing people with cirrhosis: surgery, pregnancy, travel, managing bleeding risk for invasive procedures and portal vein thrombosis