Control system design by using a multi-controller approach with a real-time experimentation for a robot wrist

The idea of the multi-controller approach is to design local controllers, each of them combined with a special environment. One problem of this approach is to select the best local controller or even several controllers in order to design the final control law, which will be applied to the plant. In this paper, a 'switching' algorithm based on a symbolic fuzzy system is used. The main goal is basically to blend the control signals provided by several controllers, which are modelreference output feedback controllers (RST controllers) in our method. Nonetheless, an interesting issue is the stability of the global structure with a reference signal. In this paper, we present research studies on the stability analysis of the proposed multi-controller approach by using Lyapunov theory and linear matrix inequalities (LMIs). The derivative of a candidate quadratic Lyapunov function is calculated thanks to a weighted sum of local derivatives. Finally, a real-time experimentation on a robot wrist shows the effectiveness of the approach.     

Evidence for two tumour suppressor loci on chromosomal bands 1p35-36 involved in neuroblastoma: one probably imprinted, another associated with N-myc amplification

Previous reports on possible genomic imprinting of the neuroblastoma tumour suppressor gene on chromosome 1p36 have been conflicting. Here we report on the parental origin of 1p36 alleles lost in 47 neuroblastomas and on a detailed Southern blot analysis of the extent of the 1p deletions in 38 cases. The results are remarkably different for tumours with and without N-myc amplification. In the N-myc single copy tumours we show that the lost 1p36 alleles are of preferential maternal origin (16 of 17 cases) and that the commonly deleted region maps to 1p36.2-3. In contrast, all N-myc amplified neuroblastomas have larger 1p deletions, extending from the telomere to at least 1p35-36.1. These deletions are of random parental origin (18 of 30 maternal LOH). This strongly suggests that different suppressor genes on 1p are inactivated in these two types of neuroblastoma. Deletion of a more proximal suppressor gene is associated with N-myc amplification, while a distal, probably imprinted, suppressor can be deleted in N-myc single copy cases.     

The Family Stories Workshop: stories for those who cannot remember

The Family Stories Workshop (FSW) is a process through which family members and friends of persons with dementing disorders living in nursing homes develop stories of these residents' lives. The stories are meant to help staff members to develop a better, more deeply felt understanding of the lives of the residents, persons who can no longer tell their own stories. The workshop is product-oriented and is not meant as a support group and works best in organizations emphasizing individualized care. This article describes the process of the FSW as well as outcomes from preliminary implementation. It suggests ways of using elements of the process to more broadly accomplish the FSW purposes.     

Insight into the lipophilicity of the aromatic N-oxide moiety

PURPOSE: A systematic study to assess the influence of N-oxygenation on the lipophilicity of aromatic weak bases was performed. METHODS: The methods used were experimental (CPC and shake-flask techniques) and computational (AMI semi-empirical method). RESULTS: The intrinsic increment in the log P(oct) system for an oxygen atom added to form an aromatic N-oxide, designated as diff(log PN(O) -N), was -1.91, but the presence of para-substituents markedly affected this value. The good linear relationship (r2 = 0.92) between diff(log PN(O) - N), and the electronic density on the oxygen atom suggests that H-bond acceptor basicity is the main structural factor responsible for the variations in lipophilicity of aromatic N-oxides. Partition coefficients of aromatic N-oxides in dodecane/buffer and chloroform/buffer systems also support this hypothesis. CONCLUSIONS: The solvent-dependent polarity of the N-oxide moiety is mainly due to its marked H-bond acceptor basicity.     

Ice Thrust in Reservoirs

We undertook a three-year program to measure the magnitude of static ice forces in four reservoirs located in central and northern Quebec. These static forces may be generated by a temperature change or may arise from such other mechanisms as water level variations, wind, and current drag force. Field observations have revealed two important facts: (1) ice covers have circumferential cracks caused either by water level variations or thermal contraction, and (2) the static ice forces are, in some instances, sufficient to trigger an instability of the broken ice covers by buckling. Noting that an ice cover cannot transmit a force to a structure larger than its own resistance, we derive an upper bound for static forces by determining the in-plane compression force at which a fragmented ice cover collapses. Empirical formulas are presented for three typical structure shapes: retaining walls, sluice gates, and piers. These formulas correlate well with the field data collected from the four dam sites, and suggest that the maximum ice thrust may simply be defined as a function of ice thickness and contact geometry.     

MPEG-4 AVC协处理器的ASIC设计

音频视频同步、内容保护和强大的系统解决方案是采用MPEG-4 AVC时需要考虑的主要因素。MPEG-4先进视频解码(AVC)已在广泛的消费与专业应用领域迅速成为主导视频编解码器,这些应用包括广播、高清DVD、安全系统和视频会议设备。采用这种强大的编码标准,即H.264的新应用正在不断推出并走向市场。因此,设计师在开发基于MPEG-4 AVC的产品时充分理解这些选择十分重要。     

Locating sensor nodes on construction projects

Localization of randomly distributed wireless sensor nodes is a significant and fundamental problem in a broad range of emerging civil engineering applications. Densely deployed in physical environments, they are envisioned to form ad hoc communication networks and provide sensed data without relying on a fixed communications infrastructure. To establish ad hoc communication networks among wireless sensor nodes, it is useful and sometimes necessary to determine sensors’ positions in static and dynamic sensor arrays. As well, the location of sensor nodes becomes of immediate use if construction resources, such as materials and components, are to be tracked. Tracking the location of construction resources enables effortless progress monitoring and supports real-time construction state sensing. This paper compares several models for localizing RFID nodes on construction job sites. They range from those based on triangulation with reference to transmission space maps, to roving RFID reader and tag systems using multiple proximity constraints, to approaches for processing uncertainty and imprecision in proximity measurements. They are compared qualitatively on the basis of cost, flexibility, scalability, computational complexity, ability to manage uncertainty and imprecision, and ability to handle dynamic sensor arrays. Results of field experiments and simulations are also presented where applicable.     

Multi-Modal Locomotion Robotic Platform Using Leg-Track-Wheel Articulations

Other than from its sensing and processing capabilities, a mobile robotic platform can be limited in its use by its ability to move in the environment. Legs, tracks and wheels are all efficient means of ground locomotion that are most suitable in different situations. Legs allow to climb over obstacles and change the height of the robot, modifying its viewpoint of the world. Tracks are efficient on uneven terrains or on soft surfaces (snow, mud, etc.), while wheels are optimal on flat surfaces. Our objective is to work on a new concept capable of combining different locomotion mechanisms to increase the locomotion capabilities of the robotic platform. The design we came up with, called AZIMUT, is symmetrical and is made of four independent leg-track-wheel articulations. It can move with its articulations up, down or straight, allowing the robot to deal with three-dimensional environments. AZIMUT is also capable of moving sideways without changing its orientation, making it omnidirectional. By putting sensors on these articulations, the robot can also actively perceive its environment by changing the orientation of its articulations. Designing a robot with such capabilities requires addressing difficult design compromises, with measurable impacts seen only after integrating all of the components together. Modularity at the structural, hardware and embedded software levels, all considered concurrently in an iterative design process, reveals to be key in the design of sophisticated mobile robotic platforms.This research is supported financially by the Canada Research Chair (CRC) program, the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Foundation for Innovation (CFI) and the Faculty of Engineering of the Université de Sherbrooke. Patent pending.François Michaud is the Canada Research Chairholder in Autonomous Mobile Robots and Intelligent Systems, and an Associate Professor at the Department of Electrical Engineering and Computer Engineering of the Université de Sherbrooke. He is the principal investigator of LABORIUS, a research laboratory working on applying AI methodologies in the design of intelligent autonomous systems that can assist humans in everyday lives. His research interests are architectural methodologies for intelligent decision making, autonomous mobile robotics, social robotics, robot learning and intelligent systems. He received his bachelors degree, Masters degree and Ph.D. degree in Electrical Engineering from the Université de Sherbrooke. He is a member of IEEE, AAAI and OIQ (Ordre des ingénieurs du Québec).Dominic Létourneau has a Bachelor degree in Computer Engineering and a Masters degree in Electrical Engineering from the Université de Sherbrooke. Since 2001, he is a research engineer at the LABORIUS Mobile Robotics and Intelligent Systems Laboratory. His research interests cover combination of systems and intelligent capabilities to increase the usability of autonomous mobile robots in the real world. His expertise lies in artificial vision, mobile robotics, robot programming and integrated design. He is a member of OIQ (Ordre des ingénieurs du Québec).Martin Arsenault has a Bachelor degree in Mechanical Engineering and from the Université de Sherbrooke. For AZIMUT, he developed the Direction subsystem.Yann Bergeron is a Mechanical Junior Engineer working in a consulting engineering firm, Groupe HBA. His field of activity is most oriented in industrial projects and construction. He received his bachelors degree in Mechanical Engineering from the University de Sherbrooke. For AZIMUT, he worked on the Track-Wheel subsystem. He is a member of OIQ (Ordre des ingénieurs du Québec) and JECQ (Jeunes entrepreneurs du Centre-du-Québec).Richard Cadrin has a Bachelor degree in Mechanical Engineering from the Université de Sherbrooke. For AZIMUT, he worked on the Propulstion subsystem.Frédéric Gagnon has a Bachelor degree in Mechanical Engineering and from the Université de Sherbrooke. For AZIMUT, he designed the chassis and worked on the integration of the articulations, the bodywork and the hardware. He is currently a research engineer at LABORIUS, working on AZIMUTs second prototype and other robotic projects. He also contributes in a mobile robotic.Marc-Antoine Legault has a Bachelor degree in Mechanical Engineering from the Université de Sherbrooke, and is currently pursuing a Masters degree at LABORIUS on serial-elastic actuators. He worked on AZIMUTs Propulsion subsystem. He also works on the design of other mobile robotic platforms. He is a member of OIQ (Ordre des ingénieurs du Québec).Mathieu Millette has a Bachelor degree in Mechanical Engineering from the Université de Sherbrooke. For AZIMUT, he developed the Tensor subsystem and he designed and integrated the battery support inside the chassis. He is now working as a junior mechanical engineer in process and technical development in a third sector mill.Jean-François Paré graduated in Mechanical Engineering from the Université de Sherbrooke. He is also trained as a professional coach from R.I.C.K. (Réseau International de Coaching Kokopelli). He launched is own business in individual coaching, team coaching, team building and coaching workshops. For businesses and individuals, he assists people in reaching their well-being and efficiency and to manifest their leadership.Marie-Christine Tremblay has obtained a Bachelor degree in Mechanical Engineering from the Université de Sherbrooke. As a part of the AZIMUTõs team, she contributed the Track-Wheel subsystem and developed a new track with high adherence and wear resistance to climb stairs. She is working in the Engineering Department at Hydra-Fab Industriel, a company conceiving electro-hydraulic systems for high speed trains.Pierre Lepage has a Computer Engineering degree from the Université de Sherbrooke. For AZIMUT, he designed the user interface to control the robot and the propulsion system. He is currently a research engineer at LABORIUS, working on AZIMUTs second prototype and other robotic projects. He is involved in research projects on coordinated behavior of a group of mobile robots. He is also actively involved in a mobile robotic startup.Yan Morin has an Electrical Engineering degree from the Université de Sherbrooke. For AZIMUT, he designed the electrical interface to control the motors of the robot. He is currently a research engineer at LABORIUS, working on AZIMUTs second prototype and other robotic projects. He is also actively involved in a mobile robotic startup.Jonathan Bisson has a Bachelor degree in Computer Engineering and a Masters degree in Electrical Engineering from the Université de Sherbrooke. His contribution to AZIMUT was on the modular distributed computing architecture. His expertise lies in electronics, motor control, embedded systems and ultrasonic transducers.Serge Caron is technician in computer systems at the Department of Electrical Engineering and Computer Engineering of the Universit de Sherbrooke. His interests are in designing mobile robotic platforms, from four-legged to wheeled robots. He is also a writer for hobbyist robotic journals.     

Stressed salmonella are exposed to reactive oxygen species from two independent sources during recovery in conventional culture media

Previously, Stephens et al. [J. Appl. Microbiol. 83 (1997) 445–455] developed a sensitive technique for studying the resuscitation of low levels of stressed Salmonella. Using this technique the influence on recovery performance of the peptone component of buffered peptone water was investigated. Within 12 different peptone types as much as 3.5 log₁₀ cells/ml difference was observed between the best and worst performing formulations. Poor recovery performance was linked to reactive oxygen species (ROS) generation through auto-oxidation of reducing sugars and photo-sensitisation of sensitive components such as riboflavin. Supplementary recovery agents were explored with only Oxyrase^®, which has both enzymes to degrade ROS and the ability to rapidly turn a medium anaerobic, having any significant effect. It improved the speed of recovery and increased, by up to 100-fold, the number of stressed cells recovered. Stressed cells were further studied by flow cytometry with cell sorting, based on the staining pattern from a novel fluorochrome combination, into good and poor recovery media. It was identified that within a stressed population the removal of all oxygen protected actively respiring cells the most by forcing them to generate energy from anaerobic metabolism thus avoiding any risk from accidental endogenous ROS generation. The recognition of two independent sources of oxidative stress in the routine use of conventional culture media is discussed in relation to pathogen detection and other areas of food microbiology.     

Molecular mechanisms of G protein-coupled receptor desensitization and resensitization

Beta-arrestin proteins play a dual role in regulating G protein-coupled receptor (GPCR) responsiveness by contributing to both receptor desensitization and internalization. Recently, beta-arrestins were also shown to be critical determinants for beta2-adrenergic receptor (beta2AR) resensitization. This was demonstrated by overexpressing wild-type beta-arrestins to rescue the resensitization-defect of a beta2AR (Y326A) mutant (gain of function) and overexpressing a dominant-negative beta-arrestin inhibitor of beta2AR sequestration to impair beta2AR dephosphorylation and resensitization (loss of function). Moreover, the ability of the beta2AR to resensitize in different cell types was shown to be dependent upon beta-arrestin expression levels. To further study the mechanisms underlying beta-arrestin function, green fluorescent protein was coupled to beta-arrestin2 (beta arr2GFP), thus allowing the real-time visualization of the agonist-dependent trafficking of beta-arrestin in living cells. Beta arr2GFP translocation from the cytoplasm to the plasma membrane proceeded with a time course, sensitivity and specificity that was indistinguishable from the most sensitive second messenger readout systems. Beta arr2GFP translocation was GRK-dependent and was demonstrated for 16 different ligand-activated GPCRs. Because beta-arrestin binding is a common divergent step in GPCR signalling, this assay represents a universal methodology for screening orphan receptors, GRK inhibitors and novel GPCR ligands. Moreover, beta arr2GFP provides a valuable new tool to dissect the biological function and regulation of beta-arrestin proteins.