bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of vagal stimulation and applied acetylcholine on pacemaker potentials in the guinea‐pig heart.
Authors: Campbell G D , Edwards F R , Hirst G D , O'Shea J E
Published: December 2014

1. Intracellular recordings were made from pacemaker cells lying in the sino‐atrial node of guinea‐pigs. 2. Low‐frequency vagal stimulation slowed the rate of generation of pacemaker action potentials; high‐frequency stimulation stopped the generation of action potentials. 3. During vagal stimulation the rate of diastolic depolarization was reduced with the action potential otherwise unchanged: when the heart stopped the membrane potential of pacemaker cells settled to a value positive of the maximum diastolic potential. 4. In contrast, added acetylcholine caused membrane hyperpolarization and shortened the duration of action potentials. 5. The effects of both added acetylcholine and vagally released acetylcholine were abolished by hyoscine. 6. It is suggested that neurally released acetylcholine acts to change the balance between inward and outward current flow during diastole by modifying the properties of existing voltage‐dependent channels. In contrast added acetylcholine appears to activate a different set of receptors which increase the potassium conductance of pacemaker cells.
The binocular input to cells in the feline dorsal lateral geniculate nucleus (dLGN).
Authors: Murphy P C , Sillito A M
Published: December 2014

1. Cells in the A laminae of the dorsal lateral geniculate nucleus receive their primary innervation from either the contralateral (A) or ipsilateral (A1) eye. This paper provides evidence concerning the responses they give to visual stimulation of what is commonly regarded as the ineffective or non‐dominant eye. It also examines the contribution of the corticofugal input to these responses. 2. Cells were identified and classified according to their responses to stimulation of the dominant eye receptive field. This was then occluded and the corresponding location in the non‐dominant eye field stimulated by a moving bar. Out of fifty‐seven cells examined forty‐three (75%) gave a response to stimulation of the non‐dominant eye. There was no obvious difference between the effects on X and Y cells in these experiments. 3. In most cases (thirty‐seven) the response involved an inhibition of the resting discharge level, but three cells gave a mixed excitatory and inhibitory response and three a pure excitatory response. All the responses were weak and only revealed by prolonged periods of averaging (20‐100 trials). 4. Ionophoretic application of the GABA antagonist N‐methyl‐bicuculline (NMB) blocked the visually elicited inhibitory effects and in most cases (twenty‐seven out of thirty‐two tested) revealed an excitatory response. Out of a further eight cells previously unresponsive to the non‐dominant eye, NMB application revealed excitatory responses in three. 5. Increasing background discharge levels and cell excitability by ionophoretic application of either acetylcholine or the excitatory amino acid, quisqualate, did not eliminate inhibitory responses and did not reveal excitatory responses. We suggest that the visually driven non‐dominant eye suppression of the background discharge involves a GABA‐mediated inhibitory input which masks an underlying excitatory input. 6. An excitatory non‐dominant eye response could potentially derive from the influence of the corticofugal projection. However, removal of the corticofugal input by aspiration of areas 17 and 18 did not reduce either the excitatory or the inhibitory components of the response. 7. In the absence of corticofugal input all cells tested (fourteen) exhibited a non‐dominant eye response and all studied during NMB application (eleven) gave an excitatory response. The primary effect of removing the corticofugal input appeared to involve the loss of a ‘damping’ influence on the excitatory and inhibitory responses, such that they were more easily revealed. The significance of these findings is discussed.
Synaptic potentials evoked in cat dorsal spinocerebellar tract neurones by impulses in single group I muscle afferents.
Authors: Walmsley B
Published: December 2014

1. Excitatory postsynaptic potentials (EPSPs) evoked by impulses in single group I muscle afferents were recorded intracellularly in dorsal spinocerebellar tract (DSCT) neurones in the spinal cords of anaesthetized cats. 2. In the same experiments, electrotonic membrane properties of DSCT neurones were measured using the voltage response of each cell to a brief intracellular current pulse. 3. Single group I fibre EPSPs were found to exhibit a large range of amplitudes, from 210 microV to 3.4 mV. All of these EPSPs exhibited uniformly rapid rise times, in contrast to the wide range of time courses exhibited by group I a EPSPs recorded in motoneurones. 4. Electrotonic analysis of DSCT neurones indicated that the time constants of these cells ranged from 5.9 to 18.2 ms, with an average value of 10.9 ms. 5. Current pulse responses of the majority (approximately three‐quarters) of DSCT neurones were well described by a simple cable model. Equivalent dendritic cable lengths were calculated for DSCT neurones and found to have an average value of 1.0 space constants, which is considerably less than that calculated for motoneurones. 6. Application of the simple cable model of DSCT neurones demonstrated that the rapid rise‐times of single group I EPSPs can be explained by a substantial somatic input to these cells. However, in addition to this strong somatic component, there may also be a contribution from dendritic synapses which prolong the initial decay phase of these EPSPs. The final decay of single fibre EPSPs in DSCT neurones is explained simply by the passive membrane time constant of these cells.
Intracellular calcium and tension during fatigue in isolated single muscle fibres from Xenopus laevis.
Authors: Allen D G , Lee J A , Westerblad H
Published: December 2014

1. Single muscle fibres were dissected from Xenopus lumbrical muscles and microinjected with the photoprotein aequorin in order to measure the myoplasmic free calcium concentration ([Ca2+]i). Fatigue was produced by repeated intermittent tetanic stimulation continued until tension had declined to approximately 50% of the initial level. Fibres were then allowed to recover by giving tetani at less frequent intervals. Aequorin light (a measure of [Ca2+]i) and tension were measured during fatiguing stimulation and recovery. 2. During fatiguing stimulation, tetanic tension declined steadily, but peak aequorin light first increased before declining substantially. The largest light signal was about 155% of initial control while at the end of fatiguing stimulation the tetanic light fell to about 14% of control. 3. Fibres showed a characteristic slowing of relaxation in the fatigued state. This was associated with a slowing of the rate of decline of the aequorin light signal. 4. Intracellular acidosis produced by equilibrating the Ringer solution with either 5 or 15% CO2 caused an increase in the light signal associated with a tetanus. Carbon dioxide also caused a reduction of tension and a slowing of relaxation. 5. In vivo pCa‐tension curves were constructed by exposing the fibres to a series of K+ concentrations which produced contractures of different sizes. Light and tension were measured during periods when both were relatively stable and the light signal was subsequently converted to pCa. 6. Exposure of fibres to 5 or 15% CO2 caused the pCa‐tension curve to be shifted to the right of the control curve. This indicates a reduced Ca2+ sensitivity of the contractile proteins, which is in agreement with results from skinned fibre studies. 7. The pCa‐tension points obtained from tetani during the early part of fatiguing stimulation also deviated to the right of the control pCa‐tension curve, suggesting a reduced Ca2+ sensitivity of the contractile proteins. At the end of fatiguing stimulation, however, pCa‐tension points did not differ greatly from the control pCa‐tension curve, suggesting that Ca2+ sensitivity was approximately normal. Thus the reduced [Ca2+]i during tetani at the end of fatiguing stimulation (when tension was reduced to approximately 50%) could explain all of the reduction in tension. 8. After fatiguing stimulation, tension and light recovered monotonically in some fibres; however, in the majority of fibres, tension and light showed a secondary decline followed by a slower recovery (post‐contractile depression). 9. During post‐contractile depression, caffeine contractures or tetani in the presence of caffeine gave increased aequorin light signals and the tension developed was close to that produced in an unfatigued tetanus.(ABSTRACT TRUNCATED AT 400 WORDS)
Breath‐by‐breath estimate of alveolar gas transfer variability in man at rest and during exercise.
Authors: di Prampero P E , Lafortuna C L
Published: December 2014

1. Breath‐by‐breath (BB) oxygen and carbon dioxide transfer (VO2 and VCO2) at the mouth, together with respiratory pattern, were determined over sequences of 100 consecutive breaths in six subjects at rest and during cycloergometric exercise (75 W). 2. BBVO2 and VCO2 at alveolar level were calculated taking the changes of pulmonary gas stores throughout each single ith breath into account. This requires knowledge of the alveolar volume at the beginning of the breath (VA.i‐1), which cannot be directly measured on a BB basis at present. Therefore a constant nominal value, ranging from 0 to 5 l, was attributed to VA,i‐1. 3. It was found that: (i) all nominal VA.i‐1 values employed for the estimate of steady‐state alveolar gas exchange yield the same average value but greatly reduce BB variability with respect to gas exchange as determined at the mouth; (ii) no unequivocal criterion was identified to select the appropriate VA.i‐1 value; and (iii) the apparent kinetics of alveolar VO2 after work onset may be influenced by the VA.i‐1 value selected for the calculation, and by the change in lung volume at the onset of exercise. 4. It was concluded that: (i) as long as VA.i‐1 cannot be measured for each single breath, ‘true’ alveolar gas exchange remains elusive; hence, (ii) it is not possible to establish the extent to which the alveolar gas exchange variability depends on physiological phenomena using available methods.
Small diameter myelinated afferents produce vasodilatation but not plasma extravasation in rat skin.
Authors: Jänig W , Lisney S J
Published: December 2014

1. Antidromic stimulation of the rat saphenous nerve at intensities sufficient to excite small myelinated (A delta) fibres but not unmyelinated (C) fibres produced evidence of a transient increase in skin blood flow in the saphenous nerve territory. The magnitude and time course of the vasodilatation depended on the number and frequency of stimuli delivered to the nerve. 2. There was no evidence of an accompanying plasma extravasation. 3. The results suggest that A delta afferent fibres are involved in axon reflex/axon response reactions as well as unmyelinated (C) afferent fibres.
On the multiple‐conductance single channels activated by excitatory amino acids in large cerebellar neurones of the rat.
Authors: Cull‐Candy S G , Usowicz M M
Published: December 2014

1. Single‐channel currents evoked by excitatory amino acids have been examined in outside‐out patches from large cerebellar neurones (including Purkinje cells) in tissue culture. L‐Glutamate (3‐10 microM), L‐aspartate (3‐10 microM), NMDA (N‐methyl‐D‐aspartate, 10‐50 microM), ibotenate (50 microM), quisqualate (3‐50 microM), and kainate (3‐50 microM) all produced single‐channel currents with multiple amplitudes. 2. Single‐channel currents recorded over a range of patch potentials had a mean interpolated reversal potential of ‐3.8 +/‐ 0.5 mV. The directly resolvable multiple conductance levels could be classified into five main groups, with mean values (averaged for all agonists) of: 47.9 +/‐ 0.7, 38.5 +/‐ 0.8, 27.8 +/‐ 1.4, 18.2 +/‐ 0.5 and 8.3 +/‐ 0.6 pS. 3. From the relative areas under current amplitude histograms it was estimated that the percentage of openings with conductances greater than 30 pS was about 83% with NMDA, 79% with glutamate and 78% with aspartate. In some patches, the majority of greater than 30 pS events evoked by these agonists were to the maximum conductance of 48 pS, whereas in other patches there were more 38 pS openings than 48 pS openings. Only 27% of quisqualate openings, and about 10% of kainate openings, were greater than 30 pS. 4. Of the small amplitude (less than 20 pS) events, 93% of quisqualate openings were to the 8 pS level whereas approximately 87% of less than 20 pS currents produced by NMDA, glutamate and aspartate were to the 18 pS level (the remainder being 8 pS). Direct transitions could occur between certain levels (including events above and below 30 pS) suggesting that these are sublevels of multiple‐conductance channels. The most frequently occurring transitions were between the 48 and 38 pS levels, and the 38 and 18 pS levels. 5. Channel openings occurred in bursts, within which individual openings were separated either by brief closures (gaps), or by direct transitions between the multiple conductance levels. The briefest of these gaps (less than 200‐400 microseconds) could represent a mixture of transitions to lower conductance levels as well as partially resolved complete shuttings. The mean duration of the longer gaps within bursts, thought to represent complete but partially resolved shuttings was 1.05 +/‐ 0.25 ms (pooled for all agonists). 6. Burst‐length distributions could be fitted with the sum of three exponentials. The briefest component may have arisen from brief single openings. The two slower components probably reflect the existence of two kinetically distinct open states.(ABSTRACT TRUNCATED AT 400 WORDS)
A Topological Framework for Flow Characterization and Identification
Authors: Tauro Flavia , Grimaldi Salvatore , Porfiri Maurizio
Published: December 2014

The characterization of complex flows is often based on kinetic and kinematic measurements computed from high dimensional sets of data. Computationally intensive processing of such large scale data sets is a major challenge in climatological and microfluidic applications. Here, we offer a novel approach based on noninvasive and unsupervised analysis of fluid flows through nonlinear manifold learning. Specifically, we study varying flow regimes in the wake of a circular cylinder by acquiring experimental video data with digital cameras and analyze the video frames with the isometric feature mapping (Isomap). We show that the topology of Isomap embedding manifolds directly captures inherent flow features without performing velocity measurements. Further, we establish relationships between the amount of embedded data and the Reynolds number, which are utilized to detect the flow regime of independent experiments.
Development and Testing of an Unmanned Aerial Vehicle for Large Scale Particle Image Velocimetry
Authors: Pagano Christopher , Tauro Flavia , Grimaldi Salvatore , Porfiri Maurizio
Published: December 2014

Large scale particle image velocimetry (LSPIV) is a nonintrusive environmental monitoring methodology that allows for continuous characterization of surface flows in natural catchments. Despite its promise, the implementation of LSPIV in natural environments is limited to areas accessible to human operators. In this work, we propose a novel experimental configuration that allows for unsupervised LSPIV over large water bodies. Specifically, we design, develop, and characterize a lightweight, low cost, and stable quadricopter hosting a digital acquisition system. An active gimbal maintains the camera lens orthogonal to the water surface, thus preventing severe image distortions. Field experiments are performed to characterize the vehicle and assess the feasibility of the approach. We demonstrate that the quadricopter can hover above an area of 1×1m2 for 4–5 minutes with a payload of 500g. Further, LSPIV measurements on a natural stream confirm that the methodology can be reliably used for surface flow studies.
Closed-Loop Control of Fluid Resuscitation via Blood Volume Estimation
Authors: Bighamian Ramin , Reisner Andrew T. , Hahn Jin-Oh
Published: December 2014

This paper presents a model-based approach to the closed-loop control of fluid resuscitation against hypovolemia. In this approach, the control system consists of a model-based blood volume estimator and a feedback controller. The model-based blood volume estimator derives relative changes in the blood volume response to the augmented fluid by analyzing an arterial blood pressure waveform and the electrocardiogram. Then, the feedback controller determines the amount of fluid to be augmented by comparing targeted versus estimated relative changes in the blood volume. In this way, unlike many previous methods for fluid resuscitation based on indirect surrogate(s) of blood volume, fluid resuscitation can be directly guided by the blood volume response. This paper reports initial design of the closed-loop control system and its simulation-based evaluation in a wide range of hypovolemic and physiologic scenarios. The results suggest that the proposed closed-loop control system is very effective in resuscitation against hypovolemia: in 97 out of 100 simulated hypovolemia, the final blood volume achieved by the control system was within 10% of its optimal value.
A Hybrid-Electric Power Transmitting Unit for 4x4 Vehicle Applications: Modeling and Simulation
Authors: Vantsevich Vladimir V. , Paldan Jesse R. , Gray Jeremy P.
Published: December 2014

In this paper, a technical concept is described for a hybrid-electric power transmitting unit (HE-PTU) to control the split of power between the drive axles of a 4×4 hybrid-electric vehicle. This new power transmitting unit is a mechatronic systems by its design and uses a planetary gear set and eddy current brake to provide a continuously variable (dynamic) gear ratio that can be integrated into the vehicle driveline between the transfer case and front axle. The paper details the electrical and mechanical characteristics of the device, including its various operation modes, its mathematical model built from the equations of the planetary gear set and eddy current brake, an optimization condition by which the device will be controlled to improve vehicle energy efficiency, as well as its torque and electrical current usage. Computer simulations are performed on a mathematical model of a 4×4 military truck using the power transmitting unit in conjunction with a series hybrid-electric configuration transmission.
Optimal Switching Synthesis for Jump Linear Systems With Gaussian Initial State Uncertainty
Authors: Lee Kooktae , Bhattacharya Raktim
Published: December 2014

This paper provides a method to design an optimal switching sequence for jump linear systems with given Gaussian initial state uncertainty. In the practical perspective, the initial state contains some uncertainties that come from measurement errors or sensor inaccuracies and we assume that the type of this uncertainty has the form of Gaussian distribution. In order to cope with Gaussian initial state uncertainty and to measure the system performance, Wasserstein metric that defines the distance between probability density functions is used. Combining with the receding horizon framework, an optimal switching sequence for jump linear systems can be obtained by minimizing the objective function that is expressed in terms of Wasserstein distance. The proposed optimal switching synthesis also guarantees the mean square stability for jump linear systems. The validations of the proposed methods are verified by examples.
Dynamic Model and Simulation of Flag Vibrations Modeled as a Membrane
Authors: Frey Gary , Carmichael Ben , Kavanaugh Joshua , Mahmoodi S. Nima
Published: December 2014

A flag is modeled as a membrane to investigate the two-dimensional characteristics of the vibration response to an uniform wind flow. Both the affecting tension and pressure functions for the wind flow with constant velocity are introduced and utilized in the modeling. In this case, the tension is caused by the weight of the flag. The pressure function is a function describing the pressure variations caused on the flag when in uniform flow. The pressure function is found by assuming that the air flow is relatively slow and that the flag is wide enough to minimize cross flow at the boundaries. An analysis of the downstream motion of the flag is necessary as well. Hamilton’s principle is employed to derive the partial differential equation of motion. The flag is oriented in the vertical direction to neglect the effect of the flag’s weight on the system’s response. Galerkin’s method is used to solve for the first four mode shapes of the system, and the system response is numerically solved. Simulations reveal a very reasonable model when the flag is modeled as a membrane.
A Model-Based Layer-to-Layer Control Algorithm for Ink-Jet 3D Printing
Authors: Lu Lu , Zheng Jian , Mishra Sandipan
Published: December 2014

Ink-jet 3D printing is a promising technology for additive manufacturing, with the potential for impacting a wide variety of industries. In traditional ink-jet 3D printing, the part is built up by depositing droplets layer upon layer in an open-loop manner. Droplet and edge dimensions are typically predicted experimentally and are assumed to remain constant through the printing process. However, there is no guarantee of consistent droplet shape and dimensions or the smoothness of the finished parts due to uncertainties in the manufacturing process. To address this issue, we propose a model-based feedback control law for ink-jet 3D printing that uses a height sensor for measuring profile height after each layer for determining the appropriate layer patterns for subsequent layers. Towards this goal, a simple model describing the relationship between profile height change and droplet deposition in the layer building process is first proposed and experimentally identified. Based on this model, a closed-loop layer-to-layer control algorithm is then developed for the ink-jet printing process. Specifically, the proposed algorithm uses a model prediction control algorithm to minimize the difference between the predicted height and the desired height and the predicted surface unevenness after a fixed number of layers. Experimental results show that the algorithm is able to achieve more consistent shapes between layers, reduced edge shrinking of the part, and smoother surface of the top layer.
Dynamic Modeling of Bottomhole Assembly
Authors: Vadali Madhu , Sun Zhijie , Xue Yuzhen , Dykstra Jason
Published: December 2014

This paper presents a comprehensive 4D dynamic model of a bottomhole assembly (BHA) used for directional drilling of oil and gas wells. Although directional drilling has been in practice for some time, it still poses several challenges, particularly related to building an autonomous drilling system. The difficulty with drilling automation derives from the complexity of the process that includes interaction with the borehole and fluid (mud) flow and complex downhole vibrations, such as bit-bounce (axial), whirl (lateral), and stick/slip (torsional). Moreover, the measurements from a limited number of downhole sensors are usually contaminated with high noise levels, and can only be transmitted at low rates with long transmission delays using mud pulsing, or at a high cost using wired pipe. Therefore, it is preferable that the directional drilling system work autonomously with limited communication to the surface. To facilitate this, a compressive physics-based model of the BHA behavior was created to be used in control system development.

In this work, the 4D dynamic model of the BHA accounts for the dynamics in rotation, axial motion, and bending along two lateral directions. The model uses a lumped mass-spring system and the system parameters (mass and stiffness) are derived from the shear beam theory of a flexible beam under certain boundary conditions.

Simulation results of the model were successful in qualitatively replicating the three types of downhole vibrations, namely bit-bounce, whirl, and stick/slip, and are discussed in this paper. The model is shown to qualitatively replicate downhole conditions and can be implemented in real-time, thereby making it suitable for autonomous directional drilling control.
Utilizing Intra-Day Prediction Modification Strategies to Improve Peak Power Shaving Using Energy Storage Systems for Smart Buildings
Authors: Wang Zheng , Clarke Adrian A. , Moyne James R. , Tilbury Dawn M.
Published: December 2014

Peak power shaving is a technique that can be used to reduce monthly electricity bills. As control of Energy Storage Systems (ESS) is based on predicted power demand, power demand forecasting is a necessary component of entire building power optimization. Various forecasting methods have been developed. However, the importance of intra-day prediction error is overlooked by present models. In this paper, a variety of dynamic intra-day model modification strategies utilizing intra-day prediction error are proposed to improve power demand prediction and peak shaving performance. These modification strategies could be applied to any models which do the prediction at the beginning of the day. A Self-Organizing Map (SOM) & Support Vector Regression (SVR) Adaptive Hybrid Model proposed in previous literature is chosen as baseline in this paper. The method of bisection is adopted to calculate the optimal threshold to control the ESS. Simulation results demonstrate effectiveness of intra-day prediction modification strategies.
Simulation-Based Design of the Geometry and Control System for an Omnidirectional Ground Vehicle
Authors: Guan Li , Niedert Andrew , Hill Richard C.
Published: December 2014

This paper describes the simulation-based design of a teleoperated, omnidirectional ground vehicle. The multi-body dynamic simulation employed is developed in the Simulink environment, specifically employing the Simscape extension of Simulink. The accuracy of the simulation is validated by comparison to data taken from one physical instantiation of the vehicle. The use of simulation allows controlled and rapid “testing” of various configurations of the vehicle without requiring any new construction and without endangering physical hardware. The simulation also provides estimates of quantities, like road force and inertial position, that are difficult to measure. The elements of the vehicle design that are specifically investigated in this paper are the vehicle’s physical geometry and its control system. The design of the vehicle’s control system is challenging because of nonlinearities and uncertainty in the model and because it is desired to control three tightly-coupled outputs (longitudinal, lateral, and angular velocity) via six different inputs (force generated at each of the vehicle’s six wheels).
A Stochastic Model Predictive Control Approach for Hybrid Electric Vehicle Energy Management With Road Grade Preview
Authors: Zeng Xiangrui , Wang Junmin
Published: December 2014

Road grade preview can benefit the hybrid electric vehicle (HEV) energy management because the energy efficiency performance degrades significantly when the battery state of charge (SOC) reaches its boundaries and the road grade has a great influence on the battery SOC balance. In reality the road grade in front may be a random variable as the future route may not always be known to the vehicle controller. This paper proposes a stochastic model predictive control (MPC) approach which does not require a determined route known in advance. The road grade is modeled as a Markov chain and all the possible future routes are considered in building the transition matrix. A large-time-scale HEV energy consumption model is built. The HEV energy management problem is formulated as a finite-horizon Markov decision process and solved using stochastic dynamic programming (SDP). Simulation results show that the proposed approach can prevent the battery SOC from reaching its boundaries and maintain good fuel efficiency by the stochastic road grade preview.
On the Use of CFD and Symbolic Dynamic Filtering for Health Monitoring of Rotating Machinery
Authors: Anusonti-Inthra Phuriwat , Chakraborty Subhadeep
Published: December 2014

This paper presents an approach to use Computational Fluid Dynamics (CFD) analysis for the development of a health monitoring system based on Symbolic Dynamic Filtering (SDF) for rotating machinery. A simplified model of a turbomachinery (single rotor) is analyzed using commercial CFD software with and without blade damages. Virtual pressure sensors are placed on the case of the turbomachinery directly above the rotating blades to measure the dynamic pressure pulse generated by the rotating blades. The pressure pulse profiles from the rotating rotor blades with and without blade damages are processed using SDF to determine the presence and magnitude of the fault. Various degrees of damage and effect of measurement noise are examined.
A Novel Algorithm for Time Optimal Trajectory Planning
Authors: Yuan Mingxing , Yao Bin , Gao Dedong , Zhu Xiaocong , Wang Qingfeng
Published: December 2014

Time optimal trajectory planning under various hard constraints plays a significant role in simultaneously meeting the requirements on high productivity and high accuracy in the fields of both machining tools and robotics. In this paper, the problem of time optimal trajectory planning is first formulated. A novel back and forward check algorithm is subsequently proposed to solve the minimum time feed-rate optimization problem. The basic idea of the algorithm is to search the feasible solution in the specified interval using the back or forward operations. Four lemmas are presented to illustrate the calculating procedure of optimal solution and the feasibility of the proposed algorithm. Both the elliptic curve and eight profile are used as case studies to verify the effectiveness of the proposed algorithm.
Adaptive Mismatch Compensation for Rate Integrating Vibratory Gyroscopes With Improved Convergence Rate
Authors: Zhang Fu , Keikha Ehsan , Shahsavari Behrooz , Horowitz Roberto
Published: December 2014

This paper presents an online adaptive algorithm to compensate damping and stiffness frequency mismatches in rate integrating Coriolis Vibratory Gyroscopes (CVGs). The proposed adaptive compensator consists of a least square estimator that estimates the damping and frequency mismatches, and an online compensator that corrects the mismatches. In order to improve the adaptive compensator’s convergence rate, we introduce a calibration phase where we identify relations between the unknown parameters (i.e. mismatches, rotation rate and rotation angle). Calibration results show that the unknown parameters lie on a hyperplane. When the gyro is in operation, we project parameters estimated from the least square estimator onto the hyperplane. The projection will reduce the degrees of freedom in parameter estimates, thus guaranteeing persistence of excitation and improving convergence rate. Simulation results show that utilization of the projection method will drastically improve convergence rate of the least square estimator and improve gyro performance.
Energy Harvesting From Building Seismic Isolation With Multi-Mode Resonant Shunt Circuits
Authors: Cao Mincan , Zuo Lei
Published: December 2014

A novel electromagnetic transducer shunt circuit is proposed in this paper for dual-functional energy harvesting and vibration control of building seismic isolation. In recent decades, base isolation systems are widely used in low and middle rise buildings. Even though base isolation can filter out high frequency excitation from earthquake, it still necessary to consider higher order modes’ vibration in host structure. The new design extends the multi-mode shunt circuit technology in piezoelectric area in order to achieve good vibration suppression into the seismic isolation of multi degree of freedoms (MDOF) of host structure of buildings, and use multi-mode circuit to achieve both energy harvesting and seismic vibration control. A numerical study of simplified two degree of freedom base isolation is presented in this paper. This passive system is also examined by giving recorded earthquake excitation. The stimulation results show that this new design could take advantage both of low-pass filtering capacity of base isolation system and resonant vibration reduction of electromagnetic shunt circuit. It is also observed that parameters selected for vibration reduction of building can effectively achieve large-scale energy harvesting at same time.
Subsea Production Two-Phase Flow Modeling and Control of Pipeline and Manifold Assemblies
Authors: Meziou Amine , Chaari Majdi , Franchek Matthew , Grigoriadis Karolos , Tafreshi Reza , Ebrahimi Behrouz
Published: December 2014

Developed in this paper is a new approach to subsea production two-phase flow modeling and control of pipeline and manifold assemblies. For that purpose, a reduced-order model is developed for transient two-phase gas-liquid flow in pipelines. First, a mechanistic model is used to calculate the steady-state pressure drop and liquid holdup. From this model, effective fluid properties are calculated and used as arguments to the dissipative distributed parameter model. A modal approximation technique is then used to render the model into a rational polynomial form appropriate for time-domain analysis and controller design. A new low-frequency magnitude correction is applied to the approximated transfer functions providing an improved matching for the steady-state gain without affecting the dynamics of the system. The resulting low-dimensional two-phase flow model is then used to coordinate the arriving pressures at the manifold for different GVF levels through electro-hydraulic valves located at the wellheads.
Automated Schematic Design of Power-Split Hybrid Vehicles With a Single Planetary Gear
Authors: Barhoumi Toumadher , Kum Dongsuk
Published: December 2014

Most of the previous research in the field of power-split hybrid electric vehicles focused on the powertrain topology optimization. However, depicting a given or found topology in the form of schematic diagram, required for the advanced steps of vehicles’ design, has not yet been studied. In this paper, we propose a systematic approach to automatically generate all feasible stick diagrams for all twelve split-hybrid powertrain topologies with a single planetary gear (PG). The stick diagram is a simplified cartoon layout that schematically illustrates the connections, arrangements, and positions of the powertrain components. The proposed process is divided into three steps. First, we introduce the placement diagram, which specifies the position of the components with respect to the planetary gear. Secondly, for each placement diagrams, all positioning diagrams are generated where the relative location of each component is determined. The use of positioning diagrams guarantees dealing with all the possible arrangements. Lastly, the feasible stick diagrams are selected by filtering out infeasible ones from the entire pool of candidate stick diagrams using a set of feasibility rules. The proposed method is used for several topologies, such as Toyota Prius and GM Volt, and it is found that the patented stick diagrams are a subset of all the feasible stick diagrams. Therefore, one can systematically generate all the feasible stick diagrams for any given single PG powertrain topology using the proposed design methodology.
Structure Analysis and Topology Optimization of a Bent-Bar-Frame Piston Based on the Variable Density Approach
Authors: Zhao Jie , Du Farong , Yao Wei
Published: December 2014

The iterative algorithm of design variables for structural topology optimization is derived by using variable density approach and Finite Element Method. A coupled model of bent-bar-frame piston is built considering the contact between piston and cylinder, piston and piston pin, piston pin and connecting rod. Based on this model, the deformation and stress of piston are analyzed under each of mechanical or thermal loading. Taking structural weight as the objective function of optimization, three desired regions of piston are optimized by using variable density approach in commercial FEA software HYPERMESH and ANSYS. Finally, the deformation and temperature of the optimized model are compared with prototype by using the same loading and boundary conditions. The results show that the weight of piston is reduced by 12.5% while meeting the required specifications.
Nonlinear Dynamics of Breathing Cracked Jeffcott Rotor Under Axial Excitation
Authors: Zhao J. , DeSmidt H. A. , Yao W.
Published: December 2014

The rotor may operate at various working conditions in practice and the crack breathing behavior at different rotating speeds is essential for damage detection and health monitoring of rotor system. In this paper, the coupling of lateral and longitudinal vibration is investigated by building a Jeffcott rotor model with imbalance. By using D’Alambert Principle, four degree-of-freedom equation of motion is derived in fixed coordinate system and the crack model is built based on the fracture mechanics. Zero SIF method is used to determine the crack open area by computing the SIF of opening mode for every point in crack area. The stiffness matrix is updated every time step by integrating compliant coefficients over instantly calculated crack open area. In addition, the breathing behavior of the crack under axial excitation is studied in terms of several eccentricity phases and rotation speeds, which provide effective guidance for damage detection in such scenarios. The paper also explores the coupling effect of external axial loading on the vibration response and its effectiveness for damage detection.
A Data-Driven Thermal Sensation Model Based Predictive Controller for Indoor Thermal Comfort and Energy Optimization
Authors: Chen Xiao , Wang Qian
Published: December 2014

This paper proposes a model predictive controller (MPC) using a data-driven thermal sensation model for indoor thermal comfort and energy optimization. The uniqueness of this empirical thermal sensation model lies in that it uses feedback from occupants (occupant actual votes) to improve the accuracy of model prediction. We evaluated the performance of our controller by comparing it with other MPC controllers developed using the Predicted Mean Vote (PMV) model as thermal comfort index. The simulation results demonstrate that in general our controller achieves a comparable level of energy consumption and comfort while eases the computation demand posed by using the PMV model in the MPC formulation. It is also worth pointing out that since we assume that our controller receives occupant feedback (votes) on thermal comfort, we do not need to monitor the parameters such as relative humidity, air velocity, mean radiant temperature and occupant clothing level changes which are necessary in the computation of PMV index. Furthermore simulations show that in cases where occupants’ actual sensation votes might deviate from the PMV predictions (i.e., a bias associated with PMV), our controller has the potential to outperform the PMV based MPC controller by providing a better indoor thermal comfort.
Alignment as Biological Inspiration for Control of Multi Agent Systems
Authors: Rastgoftar Hossein , Jayasuriya Suhada
Published: December 2014

In this paper, we develop a framework for evolution of a multi agent systems (MAS) under local perception. The idea of this paper comes from natural biological swarms where agents adjust their behavior based on individual perception of the behavior of its neighbors. Most available engineered swarms rely on local communication where an individual agent needs exact state information of its adjacent agents to evolve. We consider agents of a MAS to be particles of a continuum (deformable Body) transforming under a homogenous mapping. Homogenous transformations have the property that two crossing straight lines in an initial configuration translate as two different crossing straight lines. We will consider this feature of homogenous mappings to show how certain desired objectives can be achieved by agents of a swarm by preserving alignment among nearby agents. We show that evolution of a MAS under this alignment strategy can be achieved where agents don’t need to know the exact positions of the adjacent agents nor do they need peer to peer communication.
Repetitive Process Control of Laser Metal Deposition
Authors: Sammons Patrick M. , Bristow Douglas A. , Landers Robert G.
Published: December 2014

The Laser Metal Deposition (LMD) process is an additive manufacturing process in which a laser and a powdered material source are used to build functional metal parts in a layer by layer fashion. While the process is usually modeled by purely temporal dynamic models, the process is more aptly described as a repetitive process with two sets of dynamic processes: one that evolves in position within the layer and one that evolves in part layer. Therefore, to properly control the LMD process, it is advantageous to use a model of the LMD process that captures the dominant two dimensional phenomena and to address the two-dimensionality in process control. Using an identified spatial-domain Hammerstein model of the LMD process, the open loop process stability is examined. Then, a stabilizing controller is designed using error feedback in the layer domain.
Embedded Sensitivity Functions for Improving the Effectiveness of Vibro-Acoustic Modulation and Damage Detection on Wind Turbine Blades
Authors: Meyer Janette J. , Adams Douglas E. , Silvers Janene
Published: December 2014

In structural health monitoring, it is desirable to select sensor locations in order to minimize the number of sensors required for and the cost associated with an on-board monitoring system. When using a frequency response-based structural health monitoring technique, data measured at sensor locations which exhibit the greatest change in frequency response function (FRF) due to damage are expected to maximize the effectiveness of the chosen technique. In this work, an embedded sensitivity function is presented which identifies the sensor locations at which the maximum differences in FRFs due to damage at a known location will be observed. The formulation of the embedded sensitivity function is based on FRFs measured on a healthy structure in the frequency range in which the damage detection technique will be applied. The effectiveness of the embedded sensitivity functions in predicting the most effective sensor locations is demonstrated by applying a vibro-acoustic modulation (VAM) damage detection method to a residential-scale wind turbine blade. First, data from the healthy blade is acquired and the embedded sensitivity functions are calculated. Then, the blade is damaged and the VAM method is applied using several sensor locations. The data acquired using sensor locations identified by the embedded sensitivity functions as being most effective are shown to most clearly identify the damage on the blade.
Modeling of Piston Trajectory-Based HCCI Combustion
Authors: Zhang Chen , Li Ke , Sun Zongxuan
Published: December 2014

Previously, the authors have designed and implemented an active motion control “virtual crankshaft” for a free piston engine, which enables precise piston tracking of desired trajectories. With this mechanism, the volume of the combustion chamber can be regulated, and therefore the pressure, temperature and species concentrations of in-cylinder gas can be adjusted in real-time which affect the combustion process directly. This new degree of freedom enables us to conduct trajectory-based combustion control. In this paper, a model of the free piston engine running homogeneous charge compression ignition combustion under variant piston trajectories is presented. The variant piston trajectories have the ability to change the compression ratio and accommodate different piston motion patterns between the top dead center and the bottom dead center. The Lawrence Livermore National Laboratory reduced n-heptane reaction mechanism is employed in the model in order to describe the chemical kinetics under various piston trajectories. Analysis of the simulation results is then presented which reveals the piston trajectory effects on the combustion phenomena in terms of in-cylinder gas temperature trace, indicated output work, heat loss and radical species accumulation process.
System Characterization of MAHI Exo-II: A Robotic Exoskeleton for Upper Extremity Rehabilitation
Authors: French James A. , Rose Chad G. , O’Malley Marcia K.
Published: December 2014

This paper presents the performance characterization of the MAHI Exo-II, an upper extremity exoskeleton for stroke and spinal cord injury (SCI) rehabilitation, as a means to validate its clinical implementation and to provide depth to the literature on the performance characteristics of upper extremity exoskeletons. Individuals with disabilities arising from stroke and SCI need rehabilitation of the elbow, forearm, and wrist to restore the ability to independently perform activities of daily living (ADL). Robotic rehabilitation has been proposed to address the need for high intensity, long duration therapy and has shown promising results for upper limb proximal joints. However, upper limb distal joints have historically not benefitted from the same focus. The MAHI Exo-II, designed to address this shortcoming, has undergone a static and dynamic performance characterization, which shows that it exhibits the requisite qualities for a rehabilitation robot and is comparable to other state-of-the-art designs.
Analysis of Embedded On-Off Semi-Active Suspension Control
Authors: Varrier Sébastien , Lozoya-Santos Jorge de Jesús , Ramírez-Mendoza Ricardo A.
Published: December 2014

The analysis of recent and classical on-off controllers for semi-active suspensions are presented. The research is supported by a realistic platform consisting of an industrial ECU based on a controller area network (CAN) interfacing a real time simulation system. Two experimental models, quarter of a vehicle and semi-active (SA) damper allow to represent the realistic behavior of the vehicle and electrical/network parts. The proposed non-linear model of the SA damper permits its inclusion in the real time simulator without computing issues and valid damper characteristics. A qualitative and quantitative analysis of each controller is proposed in this paper oriented to real time implantation. The requirement for the sampling time for the analyzed controllers is discussed.
A Systematic Multi-Vehicle Platooning and Platoon Merging: Strategy, Control, and Trajectory Generation
Authors: Goli Mohammad , Eskandarian Azim
Published: December 2014

Problem of autonomous vehicle platooning in an automated highway setting has drawn many attentions, both in academia and industry, during last two decades. This paper studies the problem of vehicle platooning with a particular focus on merging control algorithm when one or several vehicle(s) merge(s) from the adjacent lane into the main vehicle platoon under longitudinal control. Different longitudinal controllers have been compared. A practical novel multi-vehicle merge-in strategy and an adaptive lateral trajectory generation method have been proposed. The proposed approach is then tested and verified in our newly developed simulation platform SimPlatoon.