Modelling and Control of Shape Memory Alloy Actuators by using Preisach Model, Genetic Algorithm and Fuzzy Logic

Shapememoryalloy (SMA) actuators, which have the ability to return to a predetermined shape when heated, have many potential applications in aeronautics, surgical tools, robotics and so on. Nonlinearity hysteresis effects existing in SMA actuators present a problem in the motion control of these smart actuators. This paper investigates the control problem of SMA actuators in both simulation and experiment. In the simulation, the numerical Preisachmodel with geometrical interpretation is used for hysteresis modeling of SMA actuators. This model is then incorporated in a closed loop PID control strategy. The optimal values of PID parameters are determined by using geneticalgorithm to minimize the mean squared error between desired output displacement and simulated output. However, the control performance is not good compared with the simulation results when these parameters are applied to the real SMA control since the system is disturbed by unknown factors and changes in the surrounding environment of the system. A further automated readjustment of the PID parameters using fuzzylogic is proposed for compensating the limitation. To demonstrate the effectiveness of the proposed controller, real time control experiment results are presented.

Predictive position and force control for shape memory alloy cylinders

In this paper, a linear lightweight electric cylinder constructed using shape memory alloy (SMA) is proposed. Spring SMA is used as the actuator to control the position and force of the cylinder rod. The model predictive control algorithm is investigated to compensate SMA hysteresis phenomenon and control the cylinder. In the predictive algorithm, the future output of the cylinder is computed based on the cylinder model, and the control signal is computed to minimize the error and power criterion. The cylinder model parameters are estimated by an online identification algorithm. Experimental results show that the SMA cylinder is able to precisely control position and force by using the predictive control strategy though the hysteresis effect existing in the actuator. The performance of the proposed controller is compared with that of a conventional PID controller

A Contested Landscape: Monuments, public memory, and post-Soviet Identity in Stavropol’, Russia

Much recent literature in cultural, political and social geography has considered the relationship between identity, memory, and the urban landscape. This paper interrogates such literature through exploring the complex materialisation of memorialisation in post-Soviet Russia. Using the example of the statue of General Alexei Ermolov in Stavropol', an analysis of the cityscape reveals interethnic tensions over differing interpretations of the life and history of the person upon whom the statue is based. The existence of a rich literature on Ermolov and the Russian colonial experience in the North Caucasus helps to explain this. The symbolic cityscape of Stavropol' plays an important role in interethnic relations in the multi-ethnic city; it is both an arena through which Russian identity is communicated with people and produced and reproduced, and an arena through which Russian citizens compete with each other for authority on historical narratives that operate at and between a number of scales. People's readings of the cityscape can reveal much about power and space in contemporary Russia.

Dual task performance of working memory and postural control in major depressive disorder

Objective: Previous studies with patients diagnosed with Major Depressive Disorder (MDD) revealed deficits in working memory and executive functions. In the present study we investigated whether patients with MDD have the ability to allocate cognitive resources in dual task performance of a highly challenging cognitive task (working memory) and a task that is seemingly automatic in nature (postural control). Method: Fifteen young (18–35 years old) patients with MDD and 24 healthy age-matched controls performed a working memory task and two postural control tasks (standing on a stable or on a moving platform) both separately (single task) and concurrently (dual task). Results: Postural stability under single task conditions was similar in the two groups, and in line with earlier studies, MDD patients recalled fewer working memory items than controls. To equate working memory challenges for patients and controls, task difficulty (number of items presented) in dual task was individually adjusted such that accuracy of working memory performance was similar for the two groups under single task conditions. Patients showed greater postural instability in dual task performance on the stable platform, and more importantly when posture task difficulty increased (moving platform) they showed deficits in both working memory accuracy and postural stability compared with healthy controls. Conclusions: We interpret our results as evidence for executive control deficits in MDD patients that affect their task coordination. In multitasking, these deficits affect not only cognitive but also sensorimotor task performance.

Valved Dataflow For FPGA Memory Hierarchy Synthesis

For modern FPGA, implementation of memory intensive processing applications such as high end image and video processing systems necessitates manual design of complex multilevel memory hierarchies incorporating off-chip DDR and onchip BRAM and LUT RAM. In fact, automated synthesis of multi-level memory hierarchies is an open problem facing high level synthesis technologies for FPGA devices. In this paper we describe the first automated solution to this problem.
By exploiting a novel dataflow application modelling dialect, known as Valved Dataflow, we show for the first time how, not only can such architectures be automatically derived, but also that the resulting implementations support real-time processing for current image processing application standards such as H.264. We demonstrate the viability of this approach by reporting the performance and cost of hierarchies automatically generated for Motion Estimation, Matrix Multiplication and Sobel Edge Detection applications on Virtex-5 FPGA.

Dead But Delightful:Tourism and Memory in New Orleans Cemeteries

The book chapter examines the history of New Orleans cemeteries and their popular image, especially in regard to the tourism industry.

Orally bioavailable small molecule drug protects memory in Alzheimer's disease models

Oligomers of beta-amyloid (Aß) are implicated in the early memory impairment seen in Alzheimer's disease before to the onset of discernable neurodegeneration. Here, the capacity of a novel orally bioavailable, central nervous system-penetrating small molecule 5-aryloxypyrimidine, SEN1500, to prevent cell-derived (7PA2 [conditioned medium] CM) Aß-induced deficits in synaptic plasticity and learned behavior was assessed. Biochemically, SEN1500 bound to Aß monomer and oligomers, produced a reduction in thioflavin-T fluorescence, and protected a neuronal cell line and primary cortical neurons exposed to synthetic soluble oligomeric Aß1-42. Electrophysiologically, SEN1500 alleviated the in vitro depression of long-term potentiation induced by both synthetic Aß1-42 and 7PA2 CM, and alleviated the in vivo depression of long-term potentiation induced by 7PA2 CM, after systemic administration. Behaviorally, oral administration of SEN1500 significantly reduced memory-related deficits in operant responding induced after intracerebroventricular injection of 7PA2 CM. SEN1500 reduced cytotoxicity, acute synaptotoxicity, and behavioral deterioration after in vitro and in vivo exposure to synthetic Aß and 7PA2 CM, and shows promise for development as a clinically viable disease-modifying Alzheimer's disease treatment. © 2013 Elsevier Inc.

Prisons Memory Archive

Between 2006 and 2007, the Prisons Memory Archive (PMA) filmed participants, including former prisoners, prison staff, teachers, chaplains, visitors, solicitors and welfare workers back inside the Maze/Long Kesh Prison and Armagh Gaol. They shared the memory of the time spent in these prisons during the period of political violence from 1970 - 2000 in Northern Ireland, commonly known as the Troubles. Underpinning the overall methodology is co-ownership of the material, which gives participants the right to veto as well as to participate in the processes of editing and exhibiting their stories, so prioritising the value of co-authorship of their stories. The PMA adopted life-story interviewing techniques with the empty sites stimulating participants’ memory while they walked and talked their way around the empty sites. A third feature is inclusivity: the archive holds stories from across the full spectrum of the prison experience. A selection of the material, with accompanying context and links is available online www.prisonsmemoryarchive.com

Further Information:

The protocols of inclusivity, co-ownership and life-story telling make this collection significant as an initiative that engages with contemporary problems of how to negotiate narratives about a conflicted past in a society emerging out of violence. Inclusivity means that prison staff, prisoners, governors, chaplains, tutors and visitors have participated, relating their individual and collective experiences, which sit side by side on the PMA website. Co-ownership addresses the issues of ethics and sensitivity, allowing key constituencies to be involved. Life-story telling, based on oral history methodologies allows participants to be the authors of their own stories, crucial when dealing with sensitive issues from a violent past. The website hosts a selection of excerpts, e.g. the Armagh Stories page shows excerpts from 15 participants, while the Maze and Long Kesh Prison page offers interactive access to 24 participants from that prison. Using an interactive documentary structure, the site offers users opportunities to navigate their own way through the material and encourages them to hear and see the ‘other’, central to attempts at encouraging dialogue in a divided society. Further, public discussions have been held after screening of excerpts with community groups in the following locations - Belfast, Newtownabbey, Derry, Armagh, Enniskillen, London, Cork, Maynooth, Clones, and Monaghan. Extracts have been screened at international academic conferences in Valencia, Australia, Tartu, Estonia, Prague, and York. A dataset of the content, with description and links, is available for REF purposes.

Hierarchical Bayesian models in ecology: Reconstructing species interaction networks from non-homogeneous species abundance data

The relationships among organisms and their surroundings can be of immense complexity. To describe and understand an ecosystem as a tangled bank, multiple ways of interaction and their effects have to be considered, such as predation, competition, mutualism and facilitation. Understanding the resulting interaction networks is a challenge in changing environments, e.g. to predict knock-on effects of invasive species and to understand how climate change impacts biodiversity. The elucidation of complex ecological systems with their interactions will benefit enormously from the development of new machine learning tools that aim to infer the structure of interaction networks from field data. In the present study, we propose a novel Bayesian regression and multiple changepoint model (BRAM) for reconstructing species interaction networks from observed species distributions. The model has been devised to allow robust inference in the presence of spatial autocorrelation and distributional heterogeneity. We have evaluated the model on simulated data that combines a trophic niche model with a stochastic population model on a 2-dimensional lattice, and we have compared the performance of our model with L1-penalized sparse regression (LASSO) and non-linear Bayesian networks with the BDe scoring scheme. In addition, we have applied our method to plant ground coverage data from the western shore of the Outer Hebrides with the objective to infer the ecological interactions. (C) 2012 Elsevier B.V. All rights reserved.

Hand-related rather than goal-related source of gaze-dependent errors in memory-guided reaching

Mechanisms for visuospatial cognition are often inferred directly from errors in behavioral reports of remembered target direction. For example, gaze-centered target representations for reach were first inferred from reach overshoots of target location relative to gaze. Here, we report evidence for the hypothesis that these gaze-dependent reach errors stem predominantly from misestimates of hand rather than target position, as was assumed in all previous studies. Subjects showed typical gaze-dependent overshoots in complete darkness, but these errors were entirely suppressed by continuous visual feedback of the finger. This manipulation could not affect target representations, so the suppressed gaze-dependent errors must have come from misestimates of hand position, likely arising in a gaze-dependent transformation of hand position signals into visual coordinates. This finding has broad implications for any task involving localization of visual targets relative to unseen limbs, in both healthy individuals and patient populations, and shows that response-related transformations cannot be ignored when deducing the sources of gaze-related errors.