Discrete Adaptive Second Order Sliding Mode Controller Design with Application to Automotive Control Systems with Model Uncertainties

Sliding mode control (SMC) is a robust and computationally efficient solution for tracking control problems of highly nonlinear systems with a great deal of uncertainty. High frequency oscillations due to chattering phenomena and sensitivity to data sampling imprecisions limit the digital implementation of conventional first order continuous-time SMC. Higher order discrete SMC is an effective solution to reduce the chattering during the controller software implementation, and also overcome imprecisions due to data sampling. In this paper, a new adaptive second order discrete sliding mode control (DSMC) formulation is presented to mitigate data sampling imprecisions and uncertainties within the modeled plant's dynamics. The adaptation mechanism is derived based on a Lyapunov stability argument which guarantees asymptotic stability of the closed-loop system. The proposed controller is designed and tested on a highly nonlinear combustion engine tracking control problem. The simulation test results show that the second order DSMC can improve the tracking performance up to 80% compared to a first order DSMC under sampling and model uncertainties.Comment: 6 pages, 6 figures, 2017 American Control Conferenc

QUANTIFYING LIFT AND DRAG FORCES IN FLATWATER KAYAKING

The purpose of this study was to develop a method of determining lift and drag forces produced by the 'wing' blade In flatwater kayaking using data digitised from cine film or videotape. The method involves six operations. 1. Recording by two cameras on film or videotape known positions of points on a three dimensional calibration frame, two reference points on the kayak, and three reference points on the shaft of the paddle. 2. Obtaining the three dimensional positions of the digitised markers using the Direct Linear Transformation (DLT) method, 3. Determining the path of the blade and its orientation with respect to the external reference frame. 4. Calculating the 'sweepback' and 'pitch' angles of the Made using the direction of the blade centre path as the reference. 5. Applying known lift and drag coefficients for each calculated sweepback and pitch angle combination to determine the magnitude of the lift and drag force vectors at each sampled instant. 6. Determining the components of the lift and drag force vectors in the desired direction of travel and using these to calculate the efficiency of the lift and drag vectors. Reliability of the method has been estimated for the operations up to operation 4 using data obtained from elite New Zealand flatwater kayak paddlers under simulated competition conditions. Research initiated by the first author at the International Center for Aquatic Research to determine the lift and drag coefficients for any given sweepback and pitch angle combination is continuing. This paper describes the operations outlined above and presents some reliability data for these operations

Measuring the speed of the conscious components of recognition memory: Remembering is faster than knowing.

Three experiments investigated response times (RTs) for remember and know responses in recognition memory. RTs to remember responses were faster than RTs to know responses, regardless of whether the remember–know decision was preceded by an old/new decision (two-step procedure) or was made without a preceding old/new decision (one-step procedure). The finding of faster RTs for R responses was also found when remember–know decisions were made retrospectively. These findings are inconsistent with dual-process models of recognition memory, which predict that recollection is slower and more effortful than familiarity. Word frequency did not influence RTs, but remember responses were faster for words than for nonwords. We argue that the difference in RTs to remember and know responses reflects the time taken to make old/new decisions on the basis of the type of information activated at test

Model Selection in Variational Mixed Effects Models

Variational inference is an alternative estimation technique for Bayesian models. Recent work shows that variational methods provide consistent estimation via efficient, deterministic algorithms. Other tools, such as model selection using variational AICs (VAIC) have been developed and studied for the linear regression case. While mixed effects models have enjoyed some study in the variational context, tools for model selection are lacking. One important feature of model selection in mixed effects models, particularly longitudinal models, is the selection of the random effects which in turn determine the covariance structure for the repeatedly sampled outcome. To address this, we derive a VAIC specifically for variational mixed effects (VME) models. We also implement a parameter-efficient VME as part of our study which reduces any general random effects structure down to a single subject-specific score. This model accommodates a wide range of random effect structures including random intercept and slope models as well as random functional effects. Our VAIC can model and perform selection on a variety of VME models including more classic longitudinal models as well as longitudinal scalar-on-function regression. As we demonstrate empirically, our VAIC performs well in discriminating between correctly and incorrectly specified random effects structures. Finally, we illustrate the use of VAICs for VMEs on two datasets: a study of lead levels in children and a study of diffusion tensor imaging

Limits on the HI content of the dwarf galaxy Hydra II

Sensitive 21cm HI observations have been made with the Green Bank Telescope toward the newly-discovered Local Group dwarf galaxy Hydra II, which may lie within the leading arm of the Magellanic Stream. No neutral hydrogen was detected. Our 5-sigma limit of MHI < 210 solar masses for a 15 km/s linewidth gives a gas-to-luminosity ratio MHI/L_V < 2.6 x 10^{-2} Mo / Lo. The limits on HI mass and MHI/L_V are typical of dwarf galaxies found within a few hundred kpc of the Milky Way. Whatever the origin of Hydra II, its neutral gas properties are not unusual.Comment: Accepted for publication in Astronomy & Astrophysic

Perceptions of rule-breaking related to marine ecosystem health

Finding effective solutions to manage marine resources is high on political and conservation agendas worldwide. This is made more urgent by the rate of increase in the human population and concomitant resource pressures in coastal areas. This paper links empirical socio-economic data about perceptions of marine resource health to the breaking of marine management rules, using fisheries as a case study. The relationship between perceived rule-breaking (non-compliance with regulations controlling fishing) and perceived health of inshore marine environments was investigated through face-to-face interviews with 299 heads of households in three Tanzanian coastal communities in November and December 2011. Awareness of rules controlling fishing activity was high among all respondents. Fishers were able to describe more specific rules controlling fishing practices than non-fishers (t = 3.5, df = 297, p < 0.01). Perceived breaking of fishing regulations was reported by nearly half of all respondents, saying “some” (32% of responses) or “most” (15% of responses) people break fishing rules. Ordinal regression modelling revealed a significant linkage (z = −3.44, p < 0.001) in the relationship between respondents' perceptions of deteriorating marine health and their perception of increased rule-breaking. In this paper, inferences from an empirical study are used to identify and argue the potential for using perceptions of ecosystem health and level of rule-breaking as a means to guide management measures. When considering different management options (e.g. Marine Protected Areas), policy makers are advised to take account of and utilise likely egoistic or altruistic decision-making factors used by fishers to determine their marine activities

Mediating Towards Forgiveness & Family Reconciliation in Divorce; Select Issues in Dispute Resolution: Apology & Forgiveness

This paper examines the importance of forgiveness and the rebuilding of trust in the reconciliation of the family during and after a divorce, and contemplates the mediator’s role in leading the parties in this direction

A study of astrocytomas in VM mice

This work consists of a study of the naturally occurring brain tumour which arises in the VM strain of mouse. This astrocytoma has clinical and pathological similarities to the human glioma. It is not known whether the appearance of such gliomas is due to pure genetic factors, the interaction of genetic and environmental influences, or the environment alone. Clinical signs consist of ruffling of the fur, development of a hunched posture, loss of hind leg spreading reflexes, ataxia and weight loss. With progression of the disease there is exaggeration of these features, together with immobility and loss of righting reflexese. Pathologically the brain shows swelling and diffuse infiltration of anaplastic astrocytoma. The VM astrocytoma can be maintained by passive transfer with intracerebral (i.c.) injections of fresh or frozen tumour homogenates into the VM and other mouse strains. Mice injected i.c. with tumour show clinical signs of severe disease about 21 days later. Passage of the astrocytoma is related to the cell density of the inoculums. Attempts at transmission with killed cells occasionally proved successful, but the cell free filtrates were ineffective. It was found that the tumour could be passaged in mice across the histocompatibility barriers into the SJL/J, C5TBL 10/ScSn and BSC strains. The tumour was also successfully transplanted into neonatal hamsters and gerbils. The VM astrocytoma was transmissible after being maintained for variable periods in tissue culture. The incubation period before clinical signs appeared was found to be dependent upon the time the tumour was maintained in culture and the cell concentrations Primary tumour cultures were effective in transferring tumours, whereas subcultures were found to be ineffective. The effects of various drugs on the VM tumour were studied in vivo and in vitro. An antiviral agent, Ribavirin (1-B-D Ribofuranosyl-1,2-4-triazole-3 carboxamide) and testosterone had no effects on the tumour when administered in vivo. Prolonged treatment of the host with Levamisole, an immunostimulant drug, prior to and following i.c. injection did not influence tumour growth. Treatment with the steroid drug Dexamethasone did reduce clinical signs and extend the survival time. Ribavirin and P113 (angiotensin II antagonist - Saralasin acetate) were examined in vitro for any inhibitory effects on tumour transmission of the cultured VM astrocytoma. In this preliminary experiment, Ribavirin appeared to be without effect, whereas the angiotensin II antagonist, P113 showed a capacity to delay outset of clinical signs. This study extends clinical and pathological data on this unique murine brain tumour

Where am i? scene recognition for mobile robots using audio features

Automatic recognition of unstructured environments is an important problem for mobile robots. We focus on using audio features to recognize different auditory environments, where they are characterized by different types of sounds. The use of audio information provides a complementary means of scene recognition that can effectively augment visual information. In particular, audio can be used toward both the analysis and characterization of the environment at a higher level of abstraction. We begin our investigation of recognizing different auditory environments with the audio information. In this paper, we utilize low-level audio features from a mobile robot and investigate using highlevel features based on spectral analysis for scene characterization, and a recognition system was built to discriminate between different environments based on these audio features found. 1