bluuebunny/crossref_metadata_2025 huggingface dataset:
Microembolic signals predict cerebral ischaemic events in patients with moyamoya disease
Authors: Chen J. , Duan L. , Xu W.‐H. , Han Y.‐Q. , Cui L.‐Y. , Gao S.
Published: March 2014

Background and purpose

Recent studies found that microembolic signals (MESs) could be detected by transcranial Doppler in patients with moyamoya disease. However, the clinical significance of MESs in moyamoya disease remains unclear. Our aim was to investigate whether the MESs could predict cerebral ischaemic events in patients with moyamoya disease.

Methods

Fifty‐four consecutive patients with moyamoya disease were recruited. MESs were monitored by transcranial Doppler for 30 min in the bilateral middle cerebral arteries of each patient on admission. Patients were followed up for 1 year. The primary end‐point was cerebral ischaemic events including stroke and transient ischaemic attack (TIA).

Results

MESs were detected in 11 (20.4%) patients, with a frequency of 11 (10.2%) in 108 hemispheres. Logistic regression analysis revealed that previous ischaemic events within 3 months were associated with the presence of MESs (odds ratio 4.41, 95% CI 1.11–17.59). During a median follow‐up of 384 days, 14 (13.0%) hemispheres had ischaemic events (seven strokes and seven TIAs). Cox regression showed that the hazard ratio for the risk of new ischaemic stroke and TIA in the hemispheres with MESs was 6.84 (95% CI 1.82–25.66) compared with those without, and 10.61 (95% CI 1.66–67.70) for ischaemic stroke alone, after controlling for age, sex, presence of ischaemic events at baseline, Suzuki stages and revascularization surgery.

Conclusions

In patients with moyamoya disease, the presence of MESs is associated with recent ischaemic symptoms and independently predicts cerebral ischaemic events. MES detection may be of potential clinical value in the management of patients with moyamoya disease.
The emerging geographies of climate justice
Authors: Fisher Susannah
Published: March 2014

Climate justice is a well used concept within the international climate debate yet it has often remained little more than a static ideal. Through an analysis of the work of a loose civil society coalition in India mobilising around climate change justice, this paper argues that we need to be more attentive to the emerging geographies of climate justice, particularly in the global South where climate change provokes questions of uneven development processes as well as environmental concerns. The paper shows how climate justice has been scaled as an international justice issue through public discourses, national policies and civil society engagement in India. I argue that this focus on international climate justice narrows the political space for alternative articulations and claims for climate justice. Whereas climate justice has tended to focus on the nation‐state as the key actor in addressing climate injustice I argue there are multiple entry points to address climate injustices at different scales. To understand what is meant by climate justice beyond the international sphere requires an exploration of the multiple manifestations and scales of climate justice and geographers could offer a critical contribution to an understanding of what national and local climate justice would mean in practice. These ideas are already starting to be operationalised in development programmes and climate finance, and a spatially grounded geographical understanding is crucial to future policy in this area.
Effectiveness and Safety of Antiplatelet in Stroke Patients with End-Stage Renal Disease Undergoing Dialysis
Authors: Chen Chung-Yu , Lee Kun-Tai , Lee Charles Tzu-Chi , Lai Wen-Ter , Huang Yaw-Bin
Published: March 2014

Background

Antiplatelet therapy is known to decrease the risk of secondary ischemic stroke. However, the effectiveness and safety of antiplatelet therapy in patients with end-stage renal disease are uncertain, especially in dialysis.

Aims and/or hypothesis

We estimated the effectiveness and safety of antiplatelet drugs (aspirin and clopidogrel) for the prevention of recurrent ischemic stroke in end-stage renal disease patients undergoing dialysis during long-term follow-up after first-time ischemic stroke.

Methods

The cases were identified from the National Health Insurance Research Database. Antiplatelet therapy was administered for 11 years to patients experiencing a first ischemic stroke between 1998 and 2006. Primary outcomes, including death and readmission to hospital for stroke, and secondary outcomes, including death, stroke, and acute myocardial infarction or bleeding, were examined.

Results

In total, 1936 patients experienced a first ischemic stroke during the follow-up. In a time-dependent analysis, the hazard ratio for primary outcomes in patients treated with aspirin was 0·671 ( P < 0·001) and that for clopidogrel was 0·933 ( P = 0·497). At secondary outcomes, patients treated with aspirin, hazard ratio for readmission for stroke was 0·715 ( P = 0·002) and that for bleeding was 0·885 ( P = 0·291). Independent risk factors for mortality and readmission due to ischemic stroke included age, diabetes mellitus, and administration of proton pump inhibitors.

Conclusions

Antiplatelet therapy, especially aspirin, still offers safe and effective treatment for ischemic stroke prevention in patients with end-stage renal disease undergoing dialysis.
A preliminary analysis of incidence of dementia in Shanghai, China
Authors: ZHANG MINGYUAN , KATZMAN ROBERT , YU ELENA , LIU WILLIAM , XIAO SHI FU , YAN HEQIN
Published: March 2014

The incidence of dementia based on DSM‐III criteria and the impact of age and education on the development of dementia using the data of a longitudinal community population survey is discussed. Study subjects were randomly sampled from the community and were assessed by a two‐stage procedure twice during a 5‐year period. The screening instrument was the Mini‐Mental State Examination and the second stage measures include a medical history and physical examination, a neurological examination and an intensive neuropsychiatric interview and testings (i.e. Blessed Dementia Scale, Activity of Daily Living, Fuld Object Memory Test and Block Design Test. All identified cases from the second stage interview were further verified by computed tomographic scan and laboratory tests. A total of 1970 subjects of non‐dementia aged 65 or older in 1987 were re‐surveyed after 5 years, of whom 114 new cases of dementia were identified. The incidence of dementia in total was 1.15% annually, 0.98% for males and 1.27% for females. The incidence for Alzheimer's disease, vascular dementia and dementia by other causes was 0.74, 0.33 and 0.08%, respectively. The highest rate (2.02%) was found in illiterate individuals. The incidence of dementia in the Shanghai cohort is similar to that from other countries. Age and education are closely related to the occurrence of dementia. While age increases by each 5 years for those aged 65 and over the likelihood of developing dementia increases nearly one‐fold (74%). Education shows great protective effect on the development of dementia. The non‐educated has a higher risk of suffering from dementia than does the educated.
New challenges of psychiatry: The development of mental health service in Shanghai
Authors: YAN HE QIN
Published: March 2014

Shanghai has a population of 13 million. In past two decades, three levels of the mental health service have been developed. It was to meet the needs of the city. Acute cases were hospitalized in time. Chronic cases were rehabilitated in community bases. All these are under the system of planning economics. In recent years, China conducted an economic reform. Shanghai was facing rapid development, psychological problems increased, the mental health service system was challenged by the market economics, insurance policy will practised. The reform of the health service system was performed in some areas. The economic constraints became the main problem for mental health facilities. In order to meet the needs of a variety of social strata, it will be necessary to develop different services: ‘The hot line', ‘crises intervention', ‘family member association', ‘psychological consulting', ‘self‐help groups', liaison–consultation psychiatry in general health care etc. Augment services will adapt to the development. The drive will be for healthy living styles to raise public awareness of mental health.
Acute Safety of an Open‐Irrigated Ablation Catheter with 56‐Hole Porous Tip for Radiofrequency Ablation of Paroxysmal Atrial Fibrillation: Analysis from 2 Observational Registry Studies
Authors: OZA SAUMIL R. , HUNTER TINA D. , BIVIANO ANGELO B. , DANDAMUDI GOPI , HERWEG BENGT , PATEL ANSHUL M. , POLLAK SCOTT J. , WANG HUIJIAN , FISHEL ROBERT S.
Published: March 2014

Acute Safety from 2 AF Ablation Registries

Introduction

This report presents safety data on the use of a new open‐irrigation radiofrequency ablation (RFA) catheter with a 56‐hole porous tip in 742 patients enrolled in 2 US prospective, multicenter observational registry studies representing real‐world use of the catheter.

Methods

This analysis is comprised of patients who underwent RFA of drug‐refractory recurrent symptomatic paroxysmal atrial fibrillation (AF). Acute adverse events (AEs) were collected and categorized by seriousness, timing, and relatedness, with 7 days of follow‐up data in one study and at least 120 days of data from a 1‐year follow‐up in the other. Acute serious adverse events (SAEs) that were identified as potentially related to the device and/or procedure were adjudicated by an independent safety committee.

Results

A total of 30 patients (4.0%) in the combined studies experienced an acute SAE related to the device and/or procedure, which was similar in the subset of patients age 65 and over (4.2%). These SAEs included 1.2% cardiac tamponade/perforation, 0.7% pericarditis, 0.5% pulmonary events, and 0.8% vascular access complications. No myocardial infarction, stroke, transient ischemic attack, or atrioesophageal fistulas within 7 days postprocedure were reported. In the study with extended follow‐up, 1 pulmonary vein stenosis and 1 esophageal injury were seen beyond 7 days postprocedure (0.2% each). There were no device or procedure related deaths.

Conclusion

Results from 2 large observational studies demonstrated that a new porous tip RFA catheter was safe for the treatment of drug refractory, recurrent, symptomatic paroxysmal AF, including treatment of older patients (≥65 years).
Improving Safety in Catheter Ablation for Atrial Fibrillation: A Prospective Study of the Use of Ultrasound to Guide Vascular Access
Authors: WYNN GARETH J. , HAQ IRAM , HUNG JOHN , BONNETT LAURA J. , LEWIS GAVIN , WEBBER MATTHEW , WAKTARE JOHAN E.P. , MODI SIMON , SNOWDON RICHARD L. , HALL MARK C.S. , TODD DERICK M. , GUPTA DHIRAJ
Published: March 2014

Vascular Ultrasound for AFA

Introduction

The most frequent complications of AF ablation (AFA) are related to vascular access, but there is little evidence as to how these can be minimized.

Methods

Consecutive patients undergoing AFA at a high‐volume center received either standard care (Group S) or routine ultrasound‐guided vascular access (Group U). Vascular complications were assessed before hospital discharge and by means of postal questionnaire 1 month later. Outcome measures were BARC 2+ bleeding complications, postprocedural pain, and prolonged bruising.

Results

Patients in Group S (n = 146) and U (n = 163) were well matched at baseline. Follow‐up questionnaires were received from 92.6%. Patients in Group U were significantly less likely to have a BARC 2+ bleed, 10.4% versus 19.9% P = 0.02, were less likely to suffer groin pain after discharge (27.1% vs. 42.8%; P = 0.006) and were less likely to experience prolonged local bruising (21.5% vs. 40.4%; P = 0.001). Multivariable logistic regression analysis revealed a significant association of vascular complications with nonultrasound guided access (OR 3.12 95%CI 1.54–5.34; P = 0.003) and increasing age (OR 1.05 95%CI 1.01–1.09; P = 0.02).

Conclusion

Routine use of ultrasound‐guided vascular access for AFA is associated with a significant reduction in bleeding complications, postprocedural pain, and prolonged bruising when compared to standard care.
Urinary serum‐ and glucocorticoid‐inducible kinase SGK1 reflects renal injury in patients with immunoglobulin A nephropathy
Authors: Lu Xiaoqian , Li Meng , Zhou Lijia , Jiang Hong , Wang Huiping , Chen Jianghua
Published: March 2014

Aim

Serum‐ and glucocorticoid‐inducible kinase SGK1 functions as an important regulator of transepithelial sodium transport by activating epithelial sodium channel in renal tubules. Considerable evidence demonstrated that SGK1 was associated with hypertension and fibrosing diseases, such as diabetic nephropathy and glomerulonephritis. The present study was performed to evaluate the role of SGK1 played in immunoglobulin A (IgA) nephropathy.

Methods

Seventy‐six patients of biopsy‐proven IgA nephropathy and 33 healthy volunteers were enrolled in this study. All patients and healthy volunteers' urinary and serum samples were tested for SGK1 expression by indirect enzyme‐linked immunosorbent assay. Meanwhile all patients' renal tissues were semi‐quantified for SGK1 expression by immunohistochemistry assay. The relationships between SGK1 expressions and clinical or pathological parameters were also assessed.

Results

SGK1 expression was upregulated in urine and renal tubules in patients of Oxford classification T1 and T2, whereas its expression in serum did not increase significantly. Relationship analysis indicated that urinary and tissue SGK1 expressions were associated with heavy proteinuria and renal insufficiency in patients with IgA nephropathy. On the other hand, RAS blockades would reduce the SGK1 levels both in urine and renal tissues.

Conclusion

These results suggested that urinary SGK1 should be a good indicator of tubulointerstitial damage in patients of IgA nephropathy. SGK1 expressions in urine and renal tissues were associated with the activity of renin‐angiotensin‐aldosterone system.
Model for estimating nutrient addition contents to staple foods fortified simultaneously: Mexico and Kampala data
Authors: Guamuch Monica , Dary Omar , Rambelson Zo , de la Cruz Vanessa , Villalpando Salvador , Tom Carol , Afidra Ronald , Makhumula Phillip
Published: March 2014

The objective of this work was to present a generic model for estimating fortification contents when several food vehicles are being considered simultaneously. It is based on approximating the magnitude of the nutritional inadequacy of the population (nutrient gap), the optimal use of the combination of food vehicles (fortifiable food energy, FFE), and the upper intake level to decrease the possibility that individuals with the highest combined intake of all food vehicles will exceed it. The model is intended to be used when only per capita food and micronutrient intake information, not detailed food intake data, are available. Food consumption survey data from Mexico and Kampala (Uganda) were analyzed for adult women, assuming that their intake may be similar to general per capita values. General adjustment factors for estimating the lowest and highest FFE and micronutrient intake for satisfying the requirements of other family members were calculated. These factors were used to estimate the additional effective content and the maximum allowable content, and then the recommended nutrient contents at the consumers’ level were chosen on the basis of technological compatibility and cost. The method should be used in other contexts to test its validity as well as its application to nonstaple foods.
Motion Planning of Uncertain Ordinary Differential Equation Systems
Authors: Hays Joe , Sandu Adrian , Sandu Corina , Hong Dennis
Published: March 2014

This work presents a novel motion planning framework, rooted in nonlinear programming theory, that treats uncertain fully and underactuated dynamical systems described by ordinary differential equations. Uncertainty in multibody dynamical systems comes from various sources, such as system parameters, initial conditions, sensor and actuator noise, and external forcing. Treatment of uncertainty in design is of paramount practical importance because all real-life systems are affected by it, and poor robustness and suboptimal performance result if it is not accounted for in a given design. In this work uncertainties are modeled using generalized polynomial chaos and are solved quantitatively using a least-square collocation method. The computational efficiency of this approach enables the inclusion of uncertainty statistics in the nonlinear programming optimization process. As such, the proposed framework allows the user to pose, and answer, new design questions related to uncertain dynamical systems. Specifically, the new framework is explained in the context of forward, inverse, and hybrid dynamics formulations. The forward dynamics formulation, applicable to both fully and underactuated systems, prescribes deterministic actuator inputs that yield uncertain state trajectories. The inverse dynamics formulation is the dual to that of forward dynamics, and is only applicable to fully actuated systems; deterministic state trajectories are prescribed and yield uncertain actuator inputs. The inverse dynamics formulation is more computationally efficient as it requires only algebraic evaluations and completely avoids numerical integration. Finally, the hybrid dynamics formulation is applicable to underactuated systems where it leverages the benefits of inverse dynamics for actuated joints and forward dynamics for unactuated joints; it prescribes actuated state and unactuated input trajectories that yield uncertain unactuated states and uncertain actuated inputs. The benefits of the ability to quantify uncertainty when planning the motion of multibody dynamic systems are illustrated through several case studies. The resulting designs determine optimal motion plans—subject to deterministic and statistical constraints—for all possible systems within the probability space.
Equivalency of Stability Transitions Between the SDS (Spectral Delay Space) and DS (Delay Space)
Authors: Gao Qingbin , Zalluhoglu Umut , Olgac Nejat
Published: March 2014

It has been shown that the stability of LTI time-delayed systems with respect to the delays can be analyzed in two equivalent domains: (i) delay space (DS) and (ii) spectral delay space (SDS). Considering a broad class of linear time-invariant time delay systems with multiple delays, the equivalency of the stability transitions along the transition boundaries is studied in both spaces. For this we follow two corresponding radial lines in DS and SDS, and prove for the first time in literature that they are equivalent. This property enables us to extract local stability transition features within the SDS without going back to the DS. The main advantage of remaining in SDS is that, one can avoid a non-linear transition from kernel hypercurves to offspring hypercurves in DS. Instead the potential stability switching curves in SDS are generated simply by stacking a finite dimensional cube called the building block (BB) along the axes. A case study is presented within the report to visualize this property.
Modeling and System Identification of Hemodynamic Responses to Vasopressor-Inotropes
Authors: Bighamian Ramin , Soleymani Sadaf , Reisner Andrew T. , Seri Istvan , Hahn Jin-Oh
Published: March 2014

In an effort to establish an initial step towards the ultimate goal of developing an analytic tool to optimize the vasopressor-inotrope therapy through individualized dose-response relationships, we propose a phenomenological model intended to reproduce the hemodynamic response to vasopressor-inotropes. The proposed model consists of a cardiovascular model relating blood pressure to cardinal cardiovascular parameters (stroke volume and total peripheral resistance) and the phenomenological relationships between the cardinal cardiovascular parameters and the vasopressor-inotrope dose, in such a way that the model can be adapted to individual patient solely based upon blood pressure and heart rate responses to medication dosing. In this paper, the preliminary validity of the proposed model is shown using the experimental epinephrine dose versus blood pressure and heart rate response data collected from five newborn piglets. Its performance and potential usefulness are discussed. It is anticipated that, potentially, the proposed phenomenological model may offer a meaningful first step towards the automated control of vasopressor-inotrope therapy.
Cost-Effective Energy Management for Hybrid Electric Heavy-Duty Truck Including Battery Aging
Authors: Pham T. H. , van den Bosch P. P. J. , Kessels J. T. B. A. , Huisman R. G. M.
Published: March 2014

Battery temperature has large impact on battery power capability and battery life time. In Hybrid Electric Heavy-duty trucks (HEVs), the high-voltage battery is normally equipped with an active Battery Thermal Management System (BTMS) guaranteeing a desired battery life time. Since the BTMS can consume a substantial amount of energy, this paper aims at integrating the Energy Management Strategy (EMS) and BTMS to minimize the overall operational cost of the truck (considering diesel fuel cost and battery life time cost). The proposed on-line strategy makes use of the Equivalent Consumption Minimization Strategy (ECMS) along with a physics-based approach to optimize both the power split (between the Internal Combustion Engine (ICE) and the Motor Generator (MG)) and the BTMS’s operation. The strategy also utilizes a quasi-static battery cycle-life model taking into account the effects of battery power and battery temperature on the battery capacity loss. Simulation results present an appropriate strategy for EMS and BTMS integration, and demonstrate the trade-off between the total vehicle fuel consumption and the battery life time.
Research on Resonant Frequency and Output Power of Piezoelectric Energy-Harvesting Micro-Device
Authors: Gao Yu-ji , Leng Yong-gang , Shen Lin-chen , Guo Yan
Published: March 2014

A vibration energy harvester is typically composed of a spring–mass system, with the advantage of high energy density, simple structure and easily being miniaturized. Recently, effects of cantilever beam’s structural parameters and cross-section shape on energy-harvesting micro-device is concerned and investigated in this paper, so as to study its performance of energy harvesting to meet the needs of low resonant frequency and maximum output power. The effect of a cantilever beam’s structure dimensions as well as quality of the mass on the device’s resonance frequency and maximum output power can be detected through formula computing. Further study on effect of a cantilever beam’s cross-section shape has also been worked out. According to the simulation experimental results gained from ANSYS with appropriate parameters defined by theoretical derivation, we manage to receive concordant conclusions. To receive a better performance of the energy harvester, we should choose a shorter, wider and thicker cantilever beam with rectangular cross-section and heavier mass at its end. However, to meet the requirement of low resonant frequency for piezoelectric vibration energy harvesting, we still need to define either an upper or a lower limit while choosing parameters of the device.
Ankle Angles During Step Turn and Straight Walk: Implications for the Design of a Steerable Ankle-Foot Prosthetic Robot
Authors: Ficanha Evandro M. , Rastgaar Mohammad , Moridian Barzin , Mahmoudian Nina
Published: March 2014

This article compares the three-dimensional angles of the ankle during step turn and straight walking. We used an infrared camera system ( Qualisys Oqus ®) to track the trajectories and angles of the foot and leg at different stages of the gait. The range of motion (ROM) of the ankle during stance periods was estimated for both straight step and step turn. The duration of combined phases of heel strike and loading response, mid stance, and terminal stance and pre-swing were determined and used to measure the average angles at each combined phase. The ROM in Inversion/Eversion (IE) increased during turning while Medial/Lateral (ML) rotation decreased and Dorsiflexion/Plantarflexion (DP) changed the least. During the turning step, ankle displacement in DP started with similar angles to straight walk (−9.68° of dorsiflexion) and progressively showed less plantarflexion (1.37° at toe off). In IE, the ankle showed increased inversion leaning the body toward the inside of the turn (angles from 5.90° to 13.61°). ML rotation initiated with an increased medial rotation of 5.68° relative to the straight walk transitioning to 12.06° of increased lateral rotation at the toe off. A novel tendon driven transtibial ankle-foot prosthetic robot with active controls in DP and IE directions was fabricated. It is shown that the robot was capable of mimicking the recorded angles of the human ankle in both straight walk and step turn.
Robust Disturbance Rejection for a Class of Nonlinear Systems Using Disturbance Observers
Authors: El-Shaer Ahmed H. , Bajodah Abdulrahman H.
Published: March 2014

This paper is concerned with disturbance rejection performance in single-input single-output (SISO) nonlinear systems that are described by uncertain linear dynamics and bounded nonlinearities. First, the nonlinear terms are transformed into an equivalent bounded disturbance at the output of a linear system. Then, a disturbance observer (DOB) is added to the closed loop to achieve robust disturbance rejection. The DOB design is formulated as an extended Luenberger observer having internal dynamics with at least an eigenvalue at the origin. The synthesis of a (sub)optimal DOB is carried out by solving multi-objective H∞ sensitivity optimization. The design approach is applied to an inverted pendulum with actuator backlash. Closed loop response shows that tracking performance is indeed greatly enhanced with the DOB.
Statistics Based Detection and Isolation of UEGO Sensor Faults
Authors: Jammoussi Hassene , Makki Imad , Filev Dimitar , Franchek Matthew
Published: March 2014

Stringent emission regulations mandated by California air regulation board (CARB) require monitoring the upstream exhaust gas oxygen (UEGO) sensor for any possible malfunction causing the vehicle emissions to exceed certain thresholds. Six faults have been identified to potentially cause the UEGO sensor performance to deteriorate and potentially lead to instability of the air-fuel ratio (AFR) control loop. These malfunctions are either due to an additional delay or an additional lag in the transition of the sensor response from lean to rich or rich to lean. Current technology detects the faults the same way (approximated by a delay type fault) and does not distinguish between the different faults. In the current paper, a statistics based approach is developed to diagnose these faults. Specifically, the characteristics of a non-normal distribution function are estimated based on the UEGO sensor output and used to detect and isolate the faults. When symmetric operation is detected, a system identification process is employed to estimate the parameters of the dynamic system and determine the type of operation. The proposed algorithm has been demonstrated on real data obtained from both Ford F150 and Mustang V6 vehicles.
Integrated Mechanistic-Empirical Modeling of Cellular Response Based on Intracellular Signaling Dynamics
Authors: Mayalu Michaëlle N. , Asada H. Harry
Published: March 2014

A hybrid modeling framework integrating a highly specific mechanistic model with highly abstract empirical model is presented. With the growing interest in the scientific and medical community for identification of therapeutic targets in treatment of disease, it is necessary to develop predictive models that can describe cellular behavior in response to environmental cues. Intracellular signaling pathways form complex networks that regulate cellular response in both health and disease. Mechanistic (or white-box) models of biochemical networks are often unable to explain comprehensive cellular response due to lack of knowledge and/or intractable complexity (especially in events distal from the cell membrane). Empirical (or black-box) models may provide a less than accurate representation of cellular response due to data deficiency and/or loss of mechanistic detail. In the proposed framework, we use a mechanistic model to capture early signaling events and apply the resulting generated internal signals (along with external inputs) to a downstream empirical sub-model. The key construct in the approach is the treatment of a cell’s biochemical network as an encoder that creates a functional internal representation of external environmental cues. The signals derived from this representation are then used to inform downstream behaviors. Using this idea, we are able to create a comprehensive framework that describes important mechanisms with sufficient detail, while representing complex or unknown mechanisms in a more abstract form. The model is verified using published biological data describing T-Cells in immune response.
Bats Versus Bugs: Collective Behavior of Prey Decreases Predation in a Biologically-Inspired Multi-Agent System
Authors: Lin Yuan , Abaid Nicole
Published: March 2014

In this paper, we establish an agent-based model to study the impact of collective behavior of a prey species on the hunting success of predators inspired by insectivorous bats and swarming insects, called “bugs”. In the model, we consider bats preying on bugs in a three-dimensional space with periodic boundaries. The bugs follow one of the two regimes: either they swarm randomly without interacting with peers, or they seek to align their velocity directions, which results in collective behavior. Simultaneously, the bats sense their environment with a sensing space inspired by big brown bats (Eptesicus fuscus) and independently prey on bugs. We define order parameters to measure the alignment and cohesion of the bugs and relate these quantities to the cohesion and the hunting success of the bats. Comparing the results when the bugs swarm randomly or collectively, we find that collectively behaving bugs tend to align, which results in relatively more cohesive groups. In addition, cohesion among bats is induced since bats may be attracted to the same localized bug group. Due to the fact that bats need to hunt more widely for groups of bugs, collectively behaving bugs suffer less predation compared to their randomly swarming counterparts. These findings are supported by the biological literature which cites protection from predation as a primary motivator for social behavior.
Robust Maneuver Based Design of Passive-Assist Devices for Augmenting Robotic Manipulator Joints
Authors: Brown W. Robert , Ulsoy A. Galip
Published: March 2014

A methodology for designing a parallel, passive-assist device to augment an active system using energy minimization based on a known maneuver is presented. Implementation of the passive-assist device can result in an improvement in system performance with respect to efficiency, reliability, and/or utility. In previous work we demonstrated this concept experimentally on a single link robot arm augmented with a torsional spring. Here we show that the concept can effectively be applied to more complicated machines performing known periodic motions by simulating a 3-link manipulator arm. The arm can be decoupled prior to optimization using inverse dynamics — greatly simplifying the optimization problem. The addition of optimized springs results in a system-wide decrease in energy consumption of 70.9%. Finally, we consider a distribution of possible maneuvers and use the concepts of robust design to find springs that increase the guaranteed energy savings at a 90% confidence level.
Vehicle Health Inferencing Using Feature-Based Neural-Symbolic Networks
Authors: Aasted Christopher M. , Lim Sunwook , Shoureshi Rahmat A.
Published: March 2014

In order to optimize the use of fault tolerant controllers for unmanned or autonomous aerial vehicles, a health diagnostics system is being developed. To autonomously determine the effect of damage on global vehicle health, a feature-based neural-symbolic network is utilized to infer vehicle health using historical data. Our current system is able to accurately characterize the extent of vehicle damage with 99.2% accuracy when tested on prior incident data. Based on the results of this work, neural-symbolic networks appear to be a useful tool for diagnosis of global vehicle health based on features of subsystem diagnostic information.
Visual Servoing for Robot Manipulators Considering Sensing and Dynamics Limitations
Authors: Wang Cong , Lin Chung-Yen , Tomizuka Masayoshi
Published: March 2014

This paper presents a control scheme of visual servoing. Real-time vision guidance is necessary in many desirable applications of industrial manipulators. Challenge comes from the limitations of visual sensing and robot dynamics. Typical industrial machine vision systems have low sampling rate and large latency. In addition, due to the large inertia of industrial manipulators, a proper consideration of robot dynamics is important. In particular, actuator saturation may cause undesirable response. In this paper, an adaptive tracking filter is used for sensing compensation. Based on the compensated vision feedback, a two-layer controller is formulated using multi-surface sliding control. System kinematics and dynamics are decoupled and handled by the two layers of the controller respectively. Further, a constrained optimal control approach is adopted to avoid actuator saturation. Validation is conducted using a SCARA robot.
Body-Segment Orientation Estimation in Rider-Bicycle Interactions With an Un-Calibrated Monocular Camera and Wearable Gyroscopes
Authors: Lu Xiang , Zhang Yizhai , Yu Kaiyan , Yi Jingang , Liu Jingtai
Published: March 2014

We present a real-time human body-segment (e.g., upper limbs) orientation estimation scheme in rider-bicycle interactions. The estimation scheme is built on the fusion of measurements of an un-calibrated monocular camera on the bicycle and a set of small wearable gyroscopes attached to rider’s upper limbs. The known optical features are conveniently collocated with the gyroscopes. The design of an extended Kalman filter (EKF) to fuse the vision/inertial measurements compensates for the drifting errors by directly integrating gyroscope measurements. The characteristic and constraints from human anatomy and the rider-bicycle interactions are used to enhance the EKF performance. We demonstrate the effectiveness of the estimation design through bicycle riding experiments. The attractive properties of the proposed pose estimation in human-machine interactions include low-cost, high-accuracy, and wearable configurations for outdoor personal activities. Although we only present the application for rider-bicycle interactions, the proposed estimation scheme is readily extended and used for other types of human-machine interactions.
Governing Parameter Changes in Nonlinear Parameter-Dependent Optimization Problems
Authors: Gupta Rohit , Kolmanovsky Ilya V.
Published: March 2014

The paper treats a class of parameter-dependent optimization/root finding problems where the minimizer or a real root need to be determined as a function of parameter. Applications of parameter-dependent optimization include spacecraft debris avoidance, adaptive control of Hybrid Electric Vehicles, engine mapping and model predictive control. In these and other problems, the parameter changes can be controlled either directly or indirectly. In this paper, the error analysis of a dynamic predictor-corrector Newton’s type algorithm is presented. Based on this analysis, an approach to govern the changes in the parameter to enable the algorithm to track the minimizer within an acceptable error bound is described. Two simulation examples are presented. In the first example the objective is to minimize the distance between points on a curve and a given set and simultaneously move as fast as possible along the given curve. In the second example we illustrate the use of this technique for aircraft flight envelope estimation. Specifically, we estimate maximum speed of an aircraft as a function of its altitude and flight path angle.
Study on Novel Tuned Mass Dampers Utilizing Plural Auxiliary Masses to Expand Vibration Suppression Performance Under the Conditions of Limited Mass Ratio
Authors: Watanabe Toru , Usuki Daiki , Seto Kazuto
Published: March 2014

This paper proposes two types of novel Tuned Multi-mass Dampers (TMMD), namely Unequally-divided TMMD (UTMMD) and Wired TMMD (WTMMD).

It is widely known that the TMMD made of plural identical tuned mass dampers (TMDs) achieves higher vibration suppression effect than a single big TMD. In this study, the idea of UTMMD made of plural unequal TMDs is presented and its vibration suppression effect is explored numerically. It is clarified that the vibration suppression effect of UTMMD is essentially the same as that of TMD, while the robustness might be slightly improved.

Meanwhile, the extension of the stroke of TMD is an important issue. WTMMD is another novel TMMD made of an auxiliary mass connected with two small auxiliary masses via wires for each. In this study, an experimental structure and WTMMD is built, and vibration suppression property of WTMMD is investigated experimentally. The WTMMD showed satisfactory vibration suppression performance.
Torque Phase Shift Control Based on Clutch Torque Estimation
Authors: Yanakiev Diana , Fujii Yuji , Tseng Eric , Pietron Gregory M. , Kucharski Joseph , Kapas Nimrod
Published: March 2014

An automatic transmission shift method is presented, in which the torque transfer phase is controlled in closed loop. This is made possible by real-time estimation of the torque transmitted by the off-going and on-coming clutches participating in the shift. Each clutch torque is determined based on measured or estimated input and output shaft torques and accelerations. To illustrate an application of the method, traditional friction elements are used to emulate one-way-clutch function during a power-on upshift.
Precision Control Through Vibration Suppression in Piezoelectric-Stepper Response
Authors: Wilcox Scott , Devasia Santosh
Published: March 2014

The main contribution of this article is to show that, when compared to single actuator steppers, the response of multi-actuator steppers can be significantly less oscillatory and these reduced oscillations allow for higher precision velocity control of a motion stage. Moreover, it is shown that the resulting motion of the motion stage is stable using a Poincaré-map approach.
Self-Reconfigurable Control System for Autonomous Vehicles
Authors: Shoureshi Rahmat A. , Lim Sunwook , Aasted Christopher M.
Published: March 2014

This paper presents a reconfigurable control design technique that integrates a robust feedback and an iterative learning control (ILC) scheme. This technique is applied to develop vehicle control systems that are tolerant to failures due to malfunctions or damages. The design procedure includes solving the robust performance condition for a feedback controller through the use of μ-synthesis that also satisfies the convergence condition for the iterative learning control rule. The effectiveness of the proposed approach is verified by simulation experiments using a radio-controlled (R/C) model airplane. The methods presented in this paper can be applied to design of global intelligent control systems to improve the operating characteristics of a vehicle and increase safety and reliability.
An Observer Based Framework to Improve Fidelity in Internet-Distributed Hardware-in-the-Loop Simulations
Authors: Tandon Akshar , Brudnak Mark J. , Stein Jeffrey L. , Ersal Tulga
Published: March 2014

Co-simulating distributed hardware-in-the-loop systems in real time over the Internet entails communication delays that can lead to significant loss of fidelity and even instability in the system. To address this challenge, this paper proposes an observer based framework that, unlike previously reported efforts, does not require the observer to know and model the observed system dynamics. This is achieved by deriving the closed-loop dynamics of the observer based on a sliding surface. Even though the resulting error system does not necessarily stay on a sliding surface, its asymptotic convergence to zero is still guaranteed. First, this idea is developed for a generic networked system simulation framework and its stability is established. Then, it is applied to a mass-spring-damper system to illustrate the mechanics of the approach on a simple, linear example and demonstrate that the approach can stabilize the system that is otherwise unstable due to delay. Finally, a vehicle-engine-driver system simulation is considered to evaluate the performance of the approach on a more realistic, nonlinear example. An improvement of up to 33% is observed in the fidelity of the simulation. The conclusion is that the approach holds a significant potential to alleviate the negative impact of delay and improve the stability and fidelity of networked system simulations. Its benefits become more pronounced as the delay increases.
Real-Time Energy-Efficient Path Planning for Unmanned Ground Vehicles Using Mission Prior Knowledge
Authors: Sadrpour Amir , Jin Jionghua (Judy) , Ulsoy A. Galip
Published: March 2014

Surveillance missions that involve unmanned ground vehicles (UGVs) include situations where a UGV has to choose between alternative paths to complete its mission. Currently, UGV missions are often limited by the available on-board energy. Thus, we propose a dynamic most energy-efficient path planning algorithm that integrates mission prior knowledge with real-time sensory information to identify the mission’s most energy-efficient path. Our proposed approach predicts and updates the distribution of energy requirement of alternative paths using recursive Bayesian estimation through two stages: (1) exploration — road segments are explored to reduce their energy prediction uncertainty; (2) exploitation — the most energy-efficient path is selected using the collected information in the exploration stage and is traversed. Our simulation results show that the proposed approach outperforms offline methods, as well as a method that only relies on exploitation to identify the most energy-efficient path.
Development of Electromagnetic Stimulation System as Treatment for Muscle Activation
Authors: Jaramillo Paola , Shoemaker Adam , Burks William , Tran Michelle , Leonessa Alexander
Published: March 2014

The presented work addresses the implementation of electromagnetic stimulation with feedback control. Preliminary testing is conducted as a proof of principle to evaluate the feasibility of the experimental system for future in vitro experiments on mice muscle. Therefore, this study focuses on applying a Proportional-Integral controller to carry out contractions of a BioMetal Fiber based on set trajectories specified to the control algorithm. The experimental setup captures the instantaneous position of the BioMetal Fiber, which is used as feedback and modulated via high frequency electromagnetic fields. Consequently, the effectiveness of the controller and the two-coil electromagnetic system are evaluated to develop improved strategies for system tracking.
Modeling and Response Analysis of Piezoelectric Flag in Wind Flow
Authors: Wynn Logan T. , Truitt Andrew , Heim Isaac , Mahmoodi S. Nima
Published: March 2014

Within the past decade, research in the piezoelectric energy harvesting field has grown significantly concerning material selection, device configurations, and actuation methods. Oscillating cantilevered piezoelectric energy harvesters are one of the more common designs. The flag is modeled as a cantilevered Euler-Bernoulli beam with a low modulus of elasticity, and the representative equation for this is broadly accepted. The wind pressure is modeled by a method that is apparently well accepted in the aerospace field. Among other modeling assumptions, the partial differential equation is considered separable. Once separated, the spatial equation is adjusted using an auxiliary function in order to determine the mode shapes. With the mode shapes characterized, the time function is rendered, which can yield representations for either a damped or undamped system. Individually, these time functions are combined with the adjusted spatial function using the Galerkin method. Plotted results represent the periodic, two-dimensional system response over time.
Reduced Order Model of Parametric Resonance of Electrostatically Actuated CNT Cantilever Resonators
Authors: Caruntu Dumitru I. , Luo Le
Published: March 2014

This paper deals with electrostatically actuated Carbon Nano-Tubes (CNT) cantilevers using Reduced Order Model (ROM) method. Forces acting on the CNT cantilever are electrostatic, van der Waals, and damping. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forces electrostatic and van der Waals are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT undergoes nonlinear parametric dynamics. The Method of Multiple Scales (MMS), and ROM are used to investigate the system under soft excitations and/or weak nonlinearities. The frequency-amplitude and frequency-phase behaviors are found in the case of parametric resonance.
Optimal Sliding Mode Gaussian Controller for Hydropower Plant With Grid Dynamics
Authors: Rittenhouse Benjamin , Sinha Alok
Published: March 2014

This paper examines the performance of an optimal sliding mode Gaussian (OSG) controller for the regulation of a hydropower plant implemented in the modeling program SIMSEN. The controller is designed to regulate grid frequency and includes the dynamics of the wicket gate servo system, turbine, and grid. Simulation results for OSG control are compared to those of more traditional LQG and PI controllers. Simulation shows that OSG control provides superior performance for the nominal system and for the system with parametric uncertainties.
Adaptive Control of Acoustic Waves in Flexible Structure
Authors: Ji Chunhua , Gao Robert X. , Fan Zhaoyan , Liang Kenneth , Pabon Jahir
Published: March 2014

An active cascading control method for suppressing acoustic waves propagating along a flexible structure is proposed, developed, and experimentally evaluated on a hanging steel beam. To ensure satisfactory performance, multiple control points are set up along the wave propagation path. A coupled feed forward control algorithm was developed to suppress both the head wave from the transmitter and the coupling waves from the wave-cancelling actuators. An equation error adaptive system identification approach was taken to extract system dynamics and avoid mode uncertainty/truncation under high frequencies. To determine the optimal controller weights and minimize wave energy, an NLMS adaptive algorithm was realized, based on the obtained models. An experimental setup, composed of a steel beam as the wave propagation medium and five cascading control stations, was developed. Experimental results have shown that, under both wide and narrow bandwidth conditions, wave energy suppression of over 98.7% has been achieved.