bluuebunny/crossref_metadata_2025 huggingface dataset:
Civility and Humiliation under the French Flag: The Tensions of Colonial Liberalism in Pondicherry, 1871–86
Authors: Raffin Anne
Published: March 2014

This article explores the extension of political “liberty” and franchise – as well as the eventual extension of citizenship rights – to Indians during the decades of France's Third Republic (1870s–80s) in French colonial India. Not only does this example stand in stark contrast to the civil position of Indians in British India at the time, but it was also something of a unique situation in the French colonial world. How did the French attempt to apply a colonial policy of liberalism to Indian communities in Pondicherry, India, whose social world was constructed upon caste‐based rituals and rules?

I argue that liberal policies that could violate caste rules concerning purity and lead to the loss of communal rights cannot be assessed without understanding how they were received and instrumentalized by the Indian population. Overall, the difficulty of transplanting liberalism in Pondicherry was not due just to the opposition of colonial society, but also due to the resistance of local Indians. Rejections of a more emancipatory agenda meant that the republican “civility” of liberty, equality and fraternity was compromised, and this illustrates one of the fundamental tensions in imperial/liberal discourse at the time.
The neurochemical changes in the innervation of human colonic mesenteric and submucosal blood vessels in Ulcerative colitis and Crohn's disease
Authors: de Fontgalland D. , Brookes S. J. , Gibbins I. , Sia T. C. , Wattchow D. A.
Published: March 2014

Background

Neurogenic inflammation involves vasodilation, oedema and sensory nerve hypersensitivity. Extrinsic sensory nerves to the intestinal wall mediate these effects and functional subsets of these extrinsic nerves can be characterized by immunohistochemical profiles. In this study such profiles were examined in samples from patients with inflammatory bowel disease (IBD), in particular ulcerative colitis (UC) and Crohn's disease (CD).

Methods

Healthy margins from cancer patients were compared to specimens from IBD patients. All nerve fibres were labelled by PGP 9.5. Double and triple labelling with TH, NPY, SP, SOM, NOS, VIP, VAChT, CGRP, TRPv1 were performed. Perivascular nerve fibres in the mesentery, and submucosa, were examined. The percentage of all labelled nerve fibres was calculated with a transect method.

Key Results

Total number of varicosities on mesenteric vessels increased in IBD but decreased around submucosal vessels. The percentage of nerve fibres around submucosal arteries labelled by SP increased from 11% in controls to 20% (UC) and 24% (CD) and mesenteric artery nerve fibres were unchanged. Nerve fibres labelled by SOM were markedly reduced surrounding submucosal arteries, from 22% to 1% (UC) and 2% (CD), but not perivascular mesenteric nerve fibres. 87 to 93% of SP immunoreactive nerve fibres were also reactive for TRvP1. TRPv1 labelling without SP was 12%in controls and increased to 40% in CD submucosal specimens.

Conclusions & Inferences

There is an increase in SP and TRPv1, and a reduction in SOM immunoreactive nerve fibres in IBD. Changes in the perivascular functional nerve subclasses may underlie the hyperaemia, and ulceration, characteristic of IBD. Furthermore, pain may relate to underlying neural changes.
Episodic outbreaks of small mammals influence predator community dynamics in an east African savanna ecosystem
Authors: Byrom Andrea E. , Craft Meggan E. , Durant Sarah M. , Nkwabi Ally J. K. , Metzger Kristine , Hampson Katie , Mduma Simon A. R. , Forrester Guy J. , Ruscoe Wendy A. , Reed Denne N. , Bukombe John , Mchetto John , Sinclair A. R. E.
Published: March 2014

Little is known about the dynamics of small mammals in tropical savanna: a critical gap in our understanding of Africa's best known ecosystems. Historical evidence suggested small mammals peak in abundance (outbreak) in Serengeti National Park (SNP), as in agricultural systems. We asked 1) what are bottom–up drivers of small mammals and 2) do predators have top–down effects? We documented dynamics of small mammals, birds of prey, and mammalian carnivores in SNP and agricultural areas. We used climatic fluctuations and differences between unmodified and agricultural systems as perturbations to examine trophic processes, key to understanding responses to climate change and increasing human pressures. Data were derived from intermittent measures of abundance collected 1968–1999, combined with systematic sampling 2000–2010 to construct a 42‐year time series. Data on abundance of black‐shouldered kites (1968–2010), eight other species of rodent‐eating birds (1997–2010), and 10 carnivore species (1993–2010) were also collated. Outbreaks occurred every 3–5 years in SNP, with low or zero abundance between peaks. There was a positive relationship between rainfall in the wet season and 1) small mammal abundance and 2) the probability of an outbreak, both of which increased with negative Southern Oscillation Index values. Rodent‐eating birds and carnivores peaked 6–12 months after small mammals. In agricultural areas, abundance remained higher than in natural habitats. Abundances of birds of prey and mammalian carnivores were extremely low in these areas and not related to small mammal abundance. Small mammals are an important food resource for higher trophic levels in the Serengeti ecosystem. Changes in climate and land use may alter their future dynamics, with cascading consequences for higher trophic levels, including threatened carnivores. Although outbreaks cause substantial damage to crops in agricultural areas, small mammals also play a vital role in maintaining some of the diversity and complexity found in African savanna ecosystems.
Making the right choice: testing the drivers of asymmetric infections within hosts and their consequences for pathology
Authors: Johnson Pieter T. J. , Koprivnikar Janet , Orlofske Sarah A. , Melbourne Brett A. , Lafonte Bryan E.
Published: March 2014

Despite the ubiquity of bilateral symmetry among animals, a long‐standing mystery centers on why parasites that infect paired organs often do so non‐randomly. Examples from diverse host and parasite taxa continue to accumulate, yet little is known about their causes or implications for host–parasite fitness. We combined field surveys, experimental infections, and parasite choice assays to evaluate both competing explanations for – and consequences of – asymmetric infections of amphibian kidneys by echinostome trematodes, which are widespread and potentially pathogenic infections of larval amphibians. Samples from 6001 hosts representing 26 species indicated that echinostome infections exhibit a consistent, right‐kidney bias, with ˜ 62% of parasites in the right kidney. This pattern could not be explained by variation in kidney size or total infection. Experimental infections of three anuran species reproduced this pattern, with 64% of infections in the right kidney, and indicated it was not the result of differential host or parasite mortality. Based on sequential infection experiments and parasite choice assays, we further showed that earlier infections did not affect the distribution of subsequently colonizing parasites and that echinostome cercariae followed host‐derived cues rather than exhibiting congenital ‘sidedness’. We advance the hypothesis that variation in the position of the right kidney along the anterior–posterior axis controls cue strength in the right nephric duct and thus determines parasite encystment. Correspondingly, anatomical measurements from a subset of larval amphibian hosts revealed that the relative position of the right kidney explained 83% of the variation in infection bias, with no additional contributions associated with kidney volume or host size. We also show that the degree of right‐kidney bias associated positively with host growth in experiments. Morphological asymmetries could therefore function as a unique form of tolerance to mitigate the consequences of infection, despite the oft‐cited costs of asymmetry for mate selection and enemy vulnerability.
Assessment of oral surgery referrals from primary care to a regional dental hospital
Authors: Halai T. , Yates J.M.
Published: March 2014

Aim

The aim of this study is to evaluate the oral surgery referrals from primary to secondary care, treatment outcomes and appropriateness of referrals. Analysis of the patients referred also enabled assessment of the suitability of teaching provided to dental undergraduates at the University of Manchester.

Materials and methods

Retrospective analysis of a randomised sample of 300 new patient oral surgery referrals to a university dental hospital.

Results

The age range of patients referred was 17–85 years (median 51 years) and 58% were women. The vast majority (97%) of referrals was from general dental practitioners (GDPs). Twenty different reasons were recorded for referral, with the most common being anticipation of surgical extraction. A significant proportion of treatment was undertaken without complications using local anaesthesia (50%), with 27% and 9% requiring sedation and general anaesthesia, respectively. Eight per cent of patients did not require treatment, whereas 5% were placed under review or referred elsewhere. Fifty‐three per cent of patients reported a medical problem or condition, of which asthma was the most common (14% of all patients). Furthermore, 51% of patients reported taking medication, most frequently salbutamol (12.7% of all patients). Thirty‐four per cent of referrals were considered inappropriate.

Conclusion

There was a relatively high rate of inappropriate referrals to secondary care. Increased understanding by GDPs of case complexity, and surgical and medical prognostic indicators could enable more patients to undergo treatment in primary care. The surgical difficulty and medical conditions of the patients evaluated appeared to be addressed in undergraduate teaching, but supplementary targeted training to GDPs may help further reduce numbers of referrals.
Growth Hormone Replacement in Patients with PHACE Association and Hypopituitarism
Authors: Uihlein Lily C. , Garzon Maria C. , Goodwin Gregory , Liang Marilyn G.
Published: March 2014

Partially empty sella with growth hormone (GH) deficiency is rarely reported in association with PHACE (posterior fossa anomalies, cervicofacial infantile hemangiomas [IHs], arterial anomalies, cardiac defects, eye anomalies, and midline/ventral defects). Consequently, little is known about the effect of GH replacement on the proliferation and involution of IHs in children with PHACE. We describe two children with PHACE and partially empty sella, both of whom received GH replacement for treatment of hypopituitarism. In our first patient we observed erythema and prominence of the vasculature in the hemangioma shortly after initiation of therapy at age 20 months, although after 4 weeks of treatment the appearance of the hemangioma stabilized and little change was seen during eight additional years of therapy. In our second patient we noted enlargement of the hemangioma after starting low‐dose GH at age 5 years, prompting discontinuation of GH replacement after 3 months of therapy. The hemangiomas continued to grow after discontinuation of GH treatment. GH administration in our patients was associated with erythema and prominence of IHs. Our findings suggest that GH replacement therapy may promote transient or more prolonged proliferation of IHs and should be administered with close clinical monitoring.
Sinus Pericranii with a Hair Collar Sign
Authors: Cheraghi Nikoo , Delano Sophia , Csikesz Courtney , Dundamadappa Sathish , Wiss Karen
Published: March 2014

Sinus pericranii is a rare vascular malformation in which the extracranial veins are connected to the intracranial venous circulation. It typically appears as a soft mass with a blue hue on the scalp. We describe a patient with sinus pericranii and associated hair collar sign.
The unstable core of global finance: Contingent valuation and governance of international accounting standards
Authors: Mügge Daniel , Stellinga Bart
Published: March 2014

Accounting standards are the foundations of the financial regulatory edifice, and global financial governance is no more stable than the asset valuations that feed it. Yet for two decades and up to this day, no international accounting rule for financial instruments – the bulk of banks' balance sheets – has emerged that was more than a temporary fix, to be succeeded by further reforms. We show how banking regulators have been central to this dynamic and how their support for applying fair value accounting to financial instruments, the cornerstone of regulatory debate, has oscillated throughout the whole period. The two common international political economy approaches to global financial governance, which analyze it either as interest‐based bargaining or as ideas‐driven expert governance, fail to account for this pattern. In contrast, we show how the contingency of financial valuations itself has made it impossible for regulators to embrace or reject a stable set of accounting rules.
Sustainability in nursing: a concept analysis
Authors: Anåker Anna , Elf Marie
Published: March 2014

Aim

The aim of this study was to describe, explore and explain the concept of sustainability in nursing.

Background

Although researchers in nursing and medicine have emphasised the issue of sustainability and health, the concept of sustainability in nursing is undefined and poorly researched. A need exists for theoretical and empirical studies of sustainability in nursing.

Design

Concept analysis as developed by Walker and Avant.

Method

Data were derived from dictionaries, international healthcare organisations and literature searches in the CINAHL and MEDLINE databases. Inclusive years for the search ranged from 1990 to 2012. A total of fourteen articles were found that referred to sustainability in nursing.

Results

Sustainability in nursing involves six defining attributes: ecology, environment, future, globalism, holism and maintenance. Antecedents of sustainability require climate change, environmental impact and awareness, confidence in the future, responsibility and a willingness to change. Consequences of sustainability in nursing include education in the areas of ecology, environment and sustainable development as well as sustainability as a part of nursing academic programs and in the description of the academic subject of nursing. Sustainability should also be part of national and international healthcare organisations. The concept was clarified herein by giving it a definition.

Conclusion

Sustainability in nursing was explored and found to contribute to sustainable development, with the ultimate goal of maintaining an environment that does not harm current and future generations' opportunities for good health. This concept analysis provides recommendations for the healthcare sector to incorporate sustainability and provides recommendations for future research.
American Opinion Toward Jews During the Nazi Era: Results from Quota Sample Polling During the 1930s and 1940s
Authors: Welch Susan
Published: March 2014

Objective

We investigate Americans’ opinions about European and American Jews between 1938 and 1945, the period from the height of Nazi domestic power to the end of the war in Europe.

Methods

Several surveys of U.S. public opinion between 1938 and 1945, reweighted to reflect national population parameters, were examined to uncover both aggregate patterns of responses and predictors of pro‐ and anti‐Jewish sentiment.

Results

We find that individuals’ social status, gender, partisan learning, and, to some extent, region affected their views on Jewish Americans and on European Jews.

Conclusion

Roosevelt's policies of speaking out against Hitler's atrocities, but yet doing nothing to facilitate more Jews to enter the United States as refugees, reflected the complexities of Americans’ opinions about Jews here and abroad but led to failure to provide a safe haven for those thousands of Jewish refugees who might have fled before the war.
Recognition of floral homeotic MADS domain transcription factors by a phytoplasmal effector, phyllogen, induces phyllody
Authors: Maejima Kensaku , Iwai Ryo , Himeno Misako , Komatsu Ken , Kitazawa Yugo , Fujita Naoko , Ishikawa Kazuya , Fukuoka Misato , Minato Nami , Yamaji Yasuyuki , Oshima Kenro , Namba Shigetou
Published: March 2014

Plant pathogens alter the course of plant developmental processes, resulting in abnormal morphology in infected host plants. Phytoplasmas are unique plant‐pathogenic bacteria that transform plant floral organs into leaf‐like structures and cause the emergence of secondary flowers. These distinctive symptoms have attracted considerable interest for many years. Here, we revealed the molecular mechanisms of the floral symptoms by focusing on a phytoplasma‐secreted protein, PHYL1, which induces morphological changes in flowers that are similar to those seen in phytoplasma‐infected plants. PHYL1 is a homolog of the phytoplasmal effector SAP54 that also alters floral development. Using yeast two‐hybrid and in planta transient co‐expression assays, we found that PHYL1 interacts with and degrades the floral homeotic MADS domain proteins SEPALLATA3 (SEP3), APETALA1 (AP1) and CAULIFLOWER (CAL). This degradation of MADS domain proteins was dependent on the ubiquitin–proteasome pathway. The expression of floral development genes downstream of SEP3 and AP1 was disrupted in 35S::PHYL1 transgenic plants. PHYL1 was genetically and functionally conserved among other phytoplasma strains and species. We designate PHYL1, SAP54 and their homologs as members of the phyllody‐inducing gene family of ‘phyllogens’.
Pheromone signaling during sexual reproduction in algae
Authors: Frenkel Johannes , Vyverman Wim , Pohnert Georg
Published: March 2014

Algae are found in all aquatic and many terrestrial habitats. They are dominant in phytoplankton and biofilms thereby contributing massively to global primary production. Since algae comprise photosynthetic representatives of the various protoctist groups their physiology and appearance is highly diverse. This diversity is also mirrored in their characteristic life cycles that exhibit various facets of ploidy and duration of the asexual phase as well as gamete morphology. Nevertheless, sexual reproduction in unicellular and colonial algae usually has as common motive that two specialized, sexually compatible haploid gametes establish physical contact and fuse. To guarantee mating success, processes during sexual reproduction are highly synchronized and regulated. This review focuses on sex pheromones of algae that play a key role in these processes. Especially, the diversity of sexual strategies as well as of the compounds involved are the focus of this contribution. Discoveries connected to algal pheromone chemistry shed light on the role of key evolutionary processes, including endosymbiotic events and lateral gene transfer, speciation and adaptation at all phylogenetic levels. But progress in this field might also in the future provide valid tools for the manipulation of aquaculture and environmental processes.
Corneal dystrophy in Friesian horses may represent a variant of pellucid marginal degeneration
Authors: Lassaline‐Utter Mary , Gemensky‐Metzler Anne J. , Scherrer Nicole M. , Stoppini Riccardo , Latimer Claire A. , MacLaren Nicole E. , Myrna Kathern E.
Published: March 2014

Objective

To describe the clinical presentation, treatment, and outcome of a corneal dystrophy in Friesian horses and to analyze affected horses' pedigrees to investigate its heritability.

Animals

Nine Friesians with bilateral disease were identified.

Procedure

Retrospective medical record review was used to identify Friesian horses exhibiting bilateral symmetric corneal lesions. Variables identified from medical records included patient sex and age at diagnosis; location, depth and size of corneal lesions; medical and surgical therapy instituted; and visual outcome. A four‐generation pedigree for each included horse was used to construct a combined pedigree.

Results

The nine included horses had an average age at diagnosis of the first eye of 10.7 years, with males (8/9) significantly more frequently affected than females (1/9), P = 0.012. Lesions were inferior and averaged 5 mm in diameter. Depth ranged from superficial facets to perforations, which developed in nine of 18 eyes. Eight of nine perforations were surgically repaired, with seven of eight repaired eyes visual at last follow‐up. All nine eyes that had not perforated remained visual. All affected horses shared a common ancestor within six generations.

Conclusions

This form of corneal dystrophy in Friesian horses, characterized by bilateral symmetric stromal loss, appears to be progressive but responds well to surgical repair, occurs more frequently in males, may have a genetic component in Friesian horses, and may be a variant of pellucid marginal degeneration.
Galerkin Approximations for Stability of Delay Differential Equations With Time Periodic Coefficients
Authors: Sadath Anwar , Vyasarayani C. P.
Published: March 2014

A numerical method to determine the stability of delay differential equations (DDEs) with time periodic coefficients is proposed. The DDE is converted into an equivalent partial differential equation (PDE) with a time periodic boundary condition (BC). The PDE, along with its BC, is then converted into a system of ordinary differential equations (ODEs) with time periodic coefficients using the Galerkin least squares approach. In the Galerkin approach, shifted Legendre polynomials are used as basis functions, allowing us to obtain explicit expressions for the approximate system of ODEs. We analyze the stability of the discretized ODEs, which represent an approximate model of the DDEs, using Floquet theory. We use numerical examples to show that the stability charts obtained with our method are in excellent agreement with those existing in the literature and those obtained from direct numerical simulation.
Bioinspired Crown-Cutter—The Impact of Tooth Quantity and Bevel Type on Tissue Deformation, Penetration Forces, and Tooth Collapsibility
Authors: Jelínek Filip , Goderie Jeffrey , van Rixel Alice , Stam Daan , Zenhorst Johan , Breedveld Paul
Published: March 2014

Current keyhole biopsy devices are rather ungainly, inaccurate, and limited in application. A keyhole biopsy harvester was designed to facilitate peripheral cancerous tissue detection and resection at high speed and accuracy. The harvester's cutting tool, the crown-cutter, was bioinspired by the sea urchin's chewing organ—Aristotle's lantern. This paper focuses on the optimization of the crown-cutter with regard to the impact of different tooth quantity and bevel type on tissue deformation, penetration forces, and tooth collapsibility. Two sets of crown-cutter designs were manufactured and tested in push-in experiments using gelatin—the first set having no bevel and differing tooth quantity (4, 6, 8, 10 teeth) and the second set of constant tooth quantity and differing bevel type (no, inner, outer, and inner and outer bevel). The gelatin surface deformation and the penetration forces were evaluated utilizing a high speed camera and a universal testing machine, respectively. The experimental results on the crown-cutters of different tooth quantity (no bevel) showed a steady increase in the tissue deformation with the increasing amount of teeth. Unlike the bevel type, the different tooth quantity revealed significant differences with regard to the tissue deformation in between 4 versus 6-teeth and 10 versus 6-teeth cutters. As for the penetration forces, the significant difference was found only between 10 and 6-teeth cutters. In conclusion, reducing the cutter's tooth quantity resulted in lower tissue deformation, whereas differing the bevel type was found to have a negligible influence. Ultimately, a high ratio of outward to inward tooth collapsibility and a relatively low inner moment of inertia proved the 6-teeth cutter to be the most optimal.
An Adaptive Control Method With Low-Resolution Encoder
Authors: Zhang Zhenyu , Olgac Nejat
Published: March 2014

An adaptive control methodology with a low-resolution encoder feedback is presented for a biomedical application, the Ros-Drill (Rotationally Oscillating Drill). It is developed primarily for ICSI (Intra-Cytoplasmic Sperm Injection) operations, with the objective of tracking a desired oscillatory motion at the tip of a microscopic glass pipette. It is an inexpensive set-up, which creates high-frequency (higher than 500 Hz) and small-amplitude (around 0.2 deg) rotational oscillations at the tip of an injection pipette. These rotational oscillations enable the pipette to drill into cell membranes with minimum biological damage. Such a motion control procedure presents no particular difficulty when it uses sufficiently precise motion sensors. However, size, costs and accessibility of technology on the hardware components severely constrain the sensory capabilities. Consequently the control mission and the trajectory tracking are adversely affected. This paper presents a dedicated novel adaptive feedback control method to achieve a satisfactory trajectory tracking capability. We demonstrate via experiments that the tracking of the harmonic rotational motion is achieved with desirable fidelity.
State Dynamics of the Epileptic Brain
Authors: Burns Samuel P. , Santaniello Sabato , Anderson William S. , Sarma Sridevi V.
Published: March 2014

Communication between specialized regions of the brain is a dynamic process allowing for different connections to accomplish different tasks. While the content of interregional communication is complex, the pattern of connectivity (i.e., which regions communicate) may lie in a lower dimensional state-space. In epilepsy, seizures elicit changes in connectivity, whose patterns shed insight into the nature of seizures and the seizure focus. We investigated connectivity in 3 patients by applying network-based analysis on multi-day subdural electrocorticographic recordings (ECoG). We found that (i) the network connectivity defines a finite set of brain states, (ii) seizures are characterized by a consistent progression of states, and (iii) the focus is isolated from surrounding regions at the seizure onset and becomes most connected in the network towards seizure termination. Our results suggest that a finite-dimensional state-space model may characterize the dynamics of the epileptic brain, and may ultimately be used to localize seizure foci.
Output Reversibility in Linear Discrete-Time Dynamical Systems
Authors: Nersesov Sergey G. , Deshmukh Venkatesh , Ghasemi Masood
Published: March 2014

Output reversibility involves dynamical systems where for every initial condition and the corresponding output there exists another initial condition such that the output generated by this initial condition is a time-reversed image of the original output with the time running forward. Through a series of necessary and sufficient conditions, we characterize output reversibility in linear single-output discrete-time dynamical systems in terms of the geometric symmetry of its eigenvalue set with respect to the unit circle in the complex plane. Furthermore, we establish that output reversibility of a linear continuous-time system implies output reversibility of its discretization regardless of the sampling rate. Finally, we present a numerical example involving a discretization of a Hamiltonian system that exhibits output reversibility.
Adaptive Optimal Power Trade-Off in Underwater Sensor Networks
Authors: Jha Devesh K. , Wettergren Thomas A. , Ray Asok
Published: March 2014

In general, sensor networks have two competing objectives: (i) maximization of network performance with respect to the probability of successful search with a specified false alarm rate for a given coverage area, and (ii) maximization of the network’s operational life. In this context, battery-powered sensing systems are operable as long as they can communicate sensed data to the processing nodes. Since both operations of sensing and communication consume energy, judicious use of these operations could effectively improve the sensor network’s lifetime. From these perspectives, the paper presents an adaptive energy management policy that will optimally allocate the available energy between sensing and communication operations at each node to maximize the network performance under specified constraints. With the assumption of fixed total energy for a sensor network operating over a time period, the problem is reduced to identification of a network topology that maximizes the probability of successful detection of targets over a surveillance region. In a two-stage optimization, a genetic algorithm-based meta-heuristic search is first used to efficiently explore the global design space, and then a local pattern search algorithm is used for convergence to an optimal solution. The results of performance evaluation are presented to validate the proposed concept.
Polymer Flow Control in Continuous Gravimetric Blenders
Authors: Cologni Alberto L. , Formentin Simone , Previdi Fabio , Savaresi Sergio M.
Published: March 2014

In this paper, the design of a plastic flow control system for continuous gravimetric blenders used in polymer extrusion processes is discussed. The considered plant is a blending machine that mixes four different polymers, bulks and additives. In order to pursue the desired behavior, three control objectives are considered: plastic flow estimation based on weight and screw speed measurements, plastic flow regulation for each meter and control of the recipe with mass constraints such that the mixer can always satisfy the plastic flow variation needed by the extruder. Simulation results are used to show the effectiveness of the proposed approach.
Invariance Control of a Class of Cascade Nonlinear Systems With Input Unmodeled Dynamics
Authors: Wu Caiyun , Dimirovski Georgi M. , Zhao Jun , Ma Ruicheng
Published: March 2014

The paper addresses the invariance control for a class of cascade nonlinear systems with unmodeled dynamics appearing at the input. A sufficient condition for the robust invariance control of the system under consideration is derived. Based on the methods of passivity and switching control of states of the linear subsystem, both the stabilization of the linear subsystem and the positive invariance of the prespecified region in state space can be ensured. Under some additional assumptions, the whole system is semi-global asymptotically stable. A simulation example is given to demonstrate the effectiveness of the proposed design procedure.
Centroidal Area-Constrained Partitioning for Robotic Networks
Authors: Patel Rushabh , Frasca Paolo , Bullo Francesco
Published: March 2014

We consider the problem of optimal coverage with area-constraints in a mobile multi-agent system. For a planar environment with an associated density function, this problem is equivalent to dividing the environment into optimal subregions such that each agent is responsible for the coverage of its own region. In this paper, we design a continuous-time distributed policy which allows a team of agents to achieve a convex area-constrained partition of a convex workspace. Our work is related to the classic Lloyd algorithm, and makes use of generalized Voronoi diagrams. We also discuss practical implementation for real mobile networks. Simulation methods are presented and discussed.
Collective Response of Zebrafish to a Mobile Robotic Fish
Authors: Butail Sachit , Bartolini Tiziana , Porfiri Maurizio
Published: March 2014

We investigate the response of groups of zebrafish, a model social organism, to a free-swimming robotic fish. The robot has a body and tail section and moves forward by beating the tail. Steering control is achieved by offsetting the beating tail with respect to the body. The color pattern and shape of the robot are informed by visual cues known to be preferred by zebrafish. A real-time multi-target tracking algorithm uses position and velocity estimates to autonomously maneuver the robot in circular trajectories. Observables of collective behavior are computed from the fish trajectory data to measure cohesiveness, polarization, and speed of the zebrafish group in two different experimental conditions. We show that while fish are significantly less polarized in the presence of the robot with an accompanying change in average speed, there is no significant change in the degree of cohesion.
Ocean Wave Energy Converters and Control Methodologies
Authors: Xie Jingjin , Zuo Lei
Published: March 2014

Ocean wave energy is an indirect form of solar energy with great potential worldwide. Technologies on extracting energy from the ocean wave have been explored for centuries and are still undergoing with challenges. The nature of ocean wave and ocean wave energy are introduced with their mathematical models in this paper. The features and working principles of three forms of mainstream ocean wave energy converters (OWEC), including floating bodies (point absorber, attenuator, and terminator), oscillating water column (OWC) and wave overtopping, are presented together with their hydrodynamic performances. The corresponding control methodologies for these ocean wave energy converters, such as latching control, declutch control, reactive control, model predictive control (MPC), etc., are analyzed in a comprehensive manner thereafter. Optimal conditions for maximum power absorption are also introduced with mathematical modeling and derivations.
Fast Modeling and Identification of Robot Dynamics Using the Lasso
Authors: Wang Cong , Yu Xiaowen , Tomizuka Masayoshi
Published: March 2014

This paper presents an approach for fast modeling and identification of robot dynamics. By using a data-driven machine learning approach, the process is simplified considerably from the conventional analytical method. Regressor selection using the Lasso (l1-norm penalized least squares regression) is used. The method is explained with a simple example of a two-link direct-drive robot. Further demonstration is given by applying the method to a three-link belt-driven robot. Promising result has been demonstrated.
Vibration Measurement and Monitoring of a Rotating Disk Using Contactless Laser Excitation
Authors: Kajiwara Itsuro , Hosoya Naoki
Published: March 2014

This paper proposes a contactless vibration testing system for rotating disks based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface without contact. The contactless vibration testing system is composed of a YAG laser, laser Doppler vibrometer and spectrum analyzer. This system makes it possible to measure vibration characteristics of structures under operation, such as vibration measurement of a rotating disk. The effectiveness of this system is confirmed by experimental and theoretical analyses. In this paper, a platter of hard disk drive is employed as an experimental object. Vibration characteristics of a rotating and non-rotating platter are measured and compared with the results of theoretical analysis.
A High Performance Tracking Control Method Based on a Disturbance Observer With Parameter Adaptation
Authors: Hyun Dong Jin , Choi Jungsu , Kong Kyoungchul
Published: March 2014

A disturbance observer (DOB) is a useful control algorithm for systems with uncertain dynamics, such as nonlinearity and time-varying dynamics. The DOB, however, is designed based on a nominal model, and its stability is sensitive to the magnitude of discrepancy between a controlled system and its nominal model. Therefore, to increase the stability margin of the DOB, it requires an accurate model identification, which is often difficult for nonlinear or uncertain systems. In this paper, the parameters of the nominal model are continuously updated by a parameter adaptation algorithm (PAA) to keep the model discrepancy small, such that the DOB is able to show its desired performance without losing stability robustness even in the presence of nonlinearity and/or time-varying dynamics. In the integration of the DOB and the PAA, however, there exists a complicated signal interaction. In this paper, such interaction problem is solved from a practical point of view; signal filtering. The proposed method shows improved performance for an electric motor system, and is verified by experimental results in this paper.
User-Independent Hand Motion Classification With Electromyography
Authors: Gibson Alison E. , Ison Mark R. , Artemiadis Panagiotis
Published: March 2014

Electromyographic (EMG) processing is an important research area with direct applications to prosthetics, exoskeletons and human-machine interaction. Current state of the art decoding methods require intensive training on a single user before it can be utilized, and have been unable to achieve both user-independence and real-time performance. This paper presents a real-time EMG classification method which generalizes across users without requiring an additional training phase. An EMG-embedded sleeve quickly positions and records from EMG surface electrodes on six forearm muscles. An optimized decision tree classifies signals from these sensors into five distinct movements for any given user using EMG energy synergies between muscles. This method was tested on 10 healthy subjects using leave-one-out validation, resulting in an overall accuracy of 79±6.6%, with sensitivity and specificity averaging 66% and 97.6%, respectively, over all classified motions. The high specificity values demonstrate the ability to generalize across users, presenting opportunities for large-scale studies and broader accessibility to EMG-driven applications.
Automatic Sensor Frame Identification in Industrial Robots With Joint Elasticity
Authors: Lin Chung-Yen , Chen Wenjie , Tomizuka Masayoshi
Published: March 2014

For robots with joint elasticity, discrepancies exist between the motor side information and the load side (i.e., end-effector) information. Therefore, high tracking performance at the load side can hardly be achieved when the estimate of load side information is inaccurate. To minimize such inaccuracies, it is desired to calibrate the load side sensor (in particular, the exact sensor location). In practice, the optimal placement of the load side sensor often varies due to the task variation necessitating frequent sensor calibrations. This frequent calibration need requires significant effort and hence is not preferable for industries which have relatively short product cycles. To solve this problem, this paper presents a sensor frame identification algorithm to automate this calibration process for the load side sensor, in particular the accelerometer. We formulate the calibration problem as a nonlinear estimation problem with unknown parameters. The Expectation-Maximization algorithm is utilized to decouple the state estimation and the parameter estimation into two separated optimization problems. An overall dual-phase learning structure associated with the proposed approach is also studied. Experiments are designed to validate the effectiveness of the proposed algorithm.
Model-Mediated Teleoperation With Predictive Models and Relative Tracking
Authors: Winck Ryder C. , Okamura Allison M.
Published: March 2014

This paper presents a model-mediated approach for teleoperation with haptic feedback in the presence of time delays on the order of seconds. The target application for the control scheme is teleoperation of robotic manipulators for space systems in geosynchronous orbit. Previous work in model-mediated teleoperation allowed operators to interact with a virtual model of the remote robot and environment, where the remote robot follows the operator’s commands after a delay and the virtual model is updated when the remote data is available. Our approach adds predictive models, mediated command execution, and a dynamic slave model. A single-degree-of-freedom experiment using a simulated robot and environment demonstrate improvements in the control of remote robot position and environment contact forces, in comparison to previous approaches.
Energy-Based Limit Cycle Compensation for Dynamically Balancing Wheeled Inverted Pendulum Machines
Authors: Vasudevan Hari , Dollar Aaron M. , Morrell John B.
Published: March 2014

In this paper we present an energy-based algorithm to minimize limit cycles in dynamically balancing wheeled inverted pendulum (IP) machines. Because the algorithm is not based on the numerical value of parameters, performance is robust and accounts for mechanical reconfiguration and wear. The effects of phenomena such as drive-train friction, rolling friction, backlash and sensor bandwidth are well known, causing either limit cycles or instabilities in IP balancing machines and yet compensation or control design to mitigate these effects are not well known. The effects of these non-linearities can be observed in the energy behavior of IP balancing machines, hence, as a broader goal we seek to establish an energy-based framework for the investigation of non-linearities in this class of machines. We successfully demonstrate the effectiveness of our algorithm on a two-wheeled IP balancing machine, “Charlie”, developed in our laboratory. As an example we show a reduction in the amplitude of limit cycles by 95.9% in wheel angle and 89.8% in pitch over a 10 second period.
Model Predictive Control of Spacecraft Relative Motion Maneuvers Using the IPA-SQP Approach
Authors: Park Hyeongjun , Kolmanovsky Ilya , Sun Jing
Published: March 2014

In this paper, a Model Predictive Controller (MPC) based on the Integrated Perturbation Analysis and Sequential Quadratic Programming (IPA-SQP) is designed and analyzed for spacecraft relative motion maneuvering. To evaluate the effectiveness of the IPA-SQP MPC, the results are compared with the linear quadratic MPC algorithm developed in [4, 13–15]. It is shown that the IPA-SQP algorithm can handle directly nonlinear constraints on thrust magnitude without resorting to saturation or polyhedral norm approximations. Spacecraft fuel consumption related metrics are examined for performance evaluation and comparison.
Output-Boundary Regulation: High-Speed AFM Imaging Application
Authors: Boekfah Arom , Devasia Santosh
Published: March 2014

This article addresses output-boundary regulation for high-scan-frequency Atomic Force Microscope (AFM) imaging of soft samples. The main contribution of this article is to use the causal inverse for nonminimum phase systems to rapidly transition an output away from a specified boundary whenever the output approaches the boundary due to unknown disturbances. The proposed feedforward-based control technique overcomes both: (i) lack of preview information of the disturbances; and (ii) performance limitations of feedback-based control methods for non-minimum phase systems. Simulation results for an example AFM are presented to illustrate the approach.
Design and Stability Analysis of Delayed Resonator With Acceleration Feedback
Authors: Vyhlídal Tomáš , Olgac Nejat , Kučera Vladimír
Published: March 2014

This paper deals with the problem of active vibration suppression using the concept of delayed resonator with acceleration feedback. A complete dynamics analysis of the resonator and its coupling with a single degree of freedom mechanical system are performed. It is shown that due to presence of a delay in the derivative feedback, the dynamics of the resonator itself, as well as the dynamics of its coupling with the system are of neutral character. Subsequently, the spectral approach is used to obtain the stability boundaries in the space of the resonator parameters. Both, analytical and numerical methods are employed in the analysis. As the contributions, we display a methodology to determine the resonator parameters in order to guarantee desirable functioning of the resonator and to provide safe stability margins. An example is included to demonstrate these analytical results.
Accounting for Parametric Model Uncertainty in Collision Avoidance for Unmanned Vehicles Using Sparse Grid Interpolation
Authors: Noble Sarah L. , Esposito Joel M. , Case Jason
Published: March 2014

In this paper we present an enhancement of model-based trajectory selection algorithms — a popular class of collision avoidance techniques for autonomous ground vehicles. Rather than dilate a set of individual candidate trajectories in an ad hoc way to account for uncertainty, we generate a set of trajectory clouds — sets of states that represent possible future poses over a product of intervals representing uncertainty in the model parameters, initial conditions and actuator commands. The clouds are generated using the sparse-grid interpolation method which is both error-controlled and computationally efficient. The approach is implemented on a differential drive vehicle.
Cooperative Trajectory Planning for Automated Farming
Authors: Remeikas Charles , Xu Yunjun , Jayasuriya Suhada
Published: March 2014

Many agricultural tasks, such as harvesting, are labor intensive. With the interests in autonomous farming, a method to rapidly generate trajectories for agricultural robots satisfying different realistic constraints becomes necessary. A hierarchical cooperative planning method is studied in this paper for a group of agricultural robots with a low computational cost. Two parts are involved in the method: once a reconfiguration event is confirmed, all the possible formation configurations will be evaluated and ranked according to their feasibility and performance index; a local pursuit strategy based cooperative trajectory planning algorithm is designed to generate optimal cooperative trajectories for robots to achieve and maintain their desired formation. To help reduce the computation cost associated with the cooperative planning algorithm, early termination conditions are proposed. The capabilities of the proposed cooperative planning algorithm are demonstrated in a simple citrus harvesting problem.
Proportional Navigation (PN) Based Tracking of Ground Targets by Quadrotor UAVs
Authors: Tan Ruoyu , Kumar Manish
Published: March 2014

This paper addresses the problem of controlling a rotary wing Unmanned Aerial Vehicle (UAV) tracking a target moving on ground. The target tracking problem by UAVs has received much attention recently and several techniques have been developed in literature most of which have been applied to fixed wing aircrafts. The use of quadrotor UAVs, the subject of this paper, for target tracking presents several challenges especially for highly maneuvering targets since the development of time-optimal controller (required if target is maneuvering fast) for quadrotor UAVs is extremely difficult due to highly non-linear dynamics. The primary contribution of this paper is the development of a proportional navigation (PN) based method and its implementation on quad-rotor UAVs to track moving ground target. The PN techniques are known to be time-optimal in nature and have been used in literature for developing guidance systems for missiles. There are several types of guidance laws that come within the broad umbrella of the PN method. The paper compares the performance of these guidance laws for their application on quadrotors and chooses the one that performs the best. Furthermore, to apply this method for target tracking instead of the traditional objective of target interception, a switching strategy has also been designed. The method has been compared with respect to the commonly used Proportional Derivative (PD) method for target tracking. The experiments and numerical simulations performed using maneuvering targets show that the proposed tracking method not only carries out effective tracking but also results into smaller oscillations and errors when compared to the widely used PD tracking method.