bluuebunny/crossref_metadata_2025 huggingface dataset:
Postsynaptic P2X3‐containing receptors in gustatory nerve fibres mediate responses to all taste qualities in mice
Authors: Vandenbeuch Aurelie , Larson Eric D. , Anderson Catherine B. , Smith Steven A. , Ford Anthony P. , Finger Thomas E. , Kinnamon Sue C.
Published: December 2014

Key points

Acute inhibition of purinergic receptors with a selective P2X3 antagonist prevents transmission of information from taste buds to sensory nerves.

The P2X3 antagonist has no effect on taste‐evoked release of ATP, confirming the effect is postsynaptic.

The results confirm previous results with P2X2/3 double knockout mice that ATP is required for transmission of all taste qualities, including sour and salty. Previously, ATP was confirmed to be required for bitter, sweet and umami tastes, but was questioned for salty and sour tastes due to pleomorphic deficits in the double knockout mice.

The geniculate ganglion in mouse contains two populations of ganglion cells with different subunit composition of P2X2 and P2X3 receptors making them differently susceptible to pharmacological block and, presumably, desensitization.

Taste buds release ATP to activate ionotropic purinoceptors composed of P2X2 and P2X3 subunits, present on the taste nerves. Mice with genetic deletion of P2X2 and P2X3 receptors (double knockout mice) lack responses to all taste stimuli presumably due to the absence of ATP‐gated receptors on the afferent nerves. Recent experiments on the double knockout mice showed, however, that their taste buds fail to release ATP, suggesting the possibility of pleiotropic deficits in these global knockouts. To test further the role of postsynaptic P2X receptors in afferent signalling, we used AF‐353, a selective antagonist of P2X3‐containing receptors to inhibit the receptors acutely during taste nerve recording and behaviour. The specificity of AF‐353 for P2X3‐containing receptors was tested by recording Ca2+ transients to exogenously applied ATP in fura‐2 loaded isolated geniculate ganglion neurons from wild‐type and P2X3 knockout mice. ATP responses were completely inhibited by 10 μm or 100 μm AF‐353, but neither concentration blocked responses in P2X3 single knockout mice wherein the ganglion cells express only P2X2‐containing receptors. Furthermore, AF‐353 had no effect on taste‐evoked ATP release from taste buds. In wild‐type mice, i.p. injection of AF‐353 or simple application of the drug directly to the tongue, inhibited taste nerve responses to all taste qualities in a dose‐dependent fashion. A brief access behavioural assay confirmed the electrophysiological results and showed that preference for a synthetic sweetener, SC‐45647, was abolished following i.p. injection of AF‐353. These data indicate that activation of P2X3‐containing receptors is required for transmission of all taste qualities.
Development of Realizable and Adaptive Wheel Torque Allocation for the Control of Planar Vehicle Dynamics
Authors: Varnhagen Scott , Anubi Olugbenga Moses , Margolis Donald
Published: December 2014

A control allocation architecture is developed for the control of the planar dynamics of a wheel motored vehicle. First, a benchmark controller is presented which takes advantage of indeterminate tire information to make informed control allocation decisions. This optimal controller is then simplified by an assumption of small slip-ratio, resulting in a controller which relies on only estimable parameters and is thus practical. Unfortunately, this suboptimal control allocation receives no information relating to tire saturation and its performance is significantly degraded compared with the optimal controller. In response, a holistic measure of tire saturation based only on estimable quantities is proposed and incorporated into the suboptimal control allocation routine. The result is a real-time implementable control system whose performance approaches that of the optimal benchmark control system.
Combined Voltage-Current Control of DC/DC Converters for Power Management of a Multi-Power Source Hybrid With HIL Tests
Authors: Moulik Bedatri , Söffker Dirk
Published: December 2014

Rising fuel prices and fast depletion of energy resources have led to an increasing interest in green technology. Hybrid vehicles due to their ability to draw power from multiple energy sources are a preferred option. Although the components such as supercapacitors, batteries, internal combustion engine, or a fuel cell, generally needed to realize a hybrid topology are known, the topology of their arrangement and realization by interchanging the components and combining different power sources, needs to be studied. In this paper, various hybrid powertrain configurations in combination with different storage elements are compared and a suitable control and power management strategy for a multi-power source powertrain system is implemented using a scalable test rig. In order to validate the component design and topology, Hardware-in-the-Loop (HiL) tests are carried out with the help of an emulator set-up.
Analysis of Sports Related mTBI Injuries Caused by Elastic Wave Propagation Through Brain Tissue
Authors: Case David , Richer Edmond
Published: December 2014

Repetitive concussions and sub-concussions suffered by athletes have been linked to a series of sequelae ranging from traumatic encephalopathy to dementia pugilistica. We developed a detailed finite element model of the human head based on standard libraries of medical imaging. The model includes realistic material properties of the brain tissue, bone, soft tissue, and cerebral spinal fluid, as well as a helmet. The strains/stresses and pressure gradients and concentrations created in the brain tissue due to propagation of waves produced by the impact through the complex internal structure of the human head for various impact scenarios were studied. This approach has the potential to expand our understanding of the mechanism of brain injury, and to better assessment of risk of delayed neurological disorders for tens of thousands of young athletes throughout the world.
A Low-Cost Rotary Optical Potentiometer Mechanism Based on Optoelectronics Technique
Authors: Kwon Young-shin , Kim Won-jong
Published: December 2014

A novel low-cost high-precision absolute rotary angle-sensing mechanism using optoelectronic components is proposed. Its working principle is based on the change of the optical power reflected off the monotone-colored pattern track from a red light emitting diode (LED) to a red-green-blue (RGB) sensor. The main advantages of this low-cost sensor are its simplicity, high resolution, and non-contacting structure. The propagation mechanism for the output voltage of the RGB sensor from a red LED source is formulated analytically. The stationary rectangular-window mask between the cylindrical black-colored V-shape track and the RGB sensor is also employed to linearize the received optical power with circular beam pattern. The effect from the black-and-white laser-printer resolution is studied with various reference angles using a high-precision potentiometer. The performance of the proposed optical rotary potentiometer mechanism is demonstrated using a rotary position-control test bed. The bandwidth (BW) of 4.42 kHz, resolution of 0.167°, and nonlinearity of 2.8% are achieved.
Simultaneous Control of an Ankle-Foot Prosthesis Model Using a Virtual Constraint
Authors: Nanjangud Akshay , Gregg Robert D.
Published: December 2014

Amputee locomotion can benefit from recent advances in robotic prostheses, but their control systems design poses challenges. Prosthesis control typically discretizes the nonlinear gait cycle into phases, with each phase controlled by different linear controllers. Unfortunately, real-time identification of gait phases and tuning of controller parameters limit implementation. Recently, biped robots have used phase variables and virtual constraints to characterize the gait cycle as a whole. Although phase variables and virtual constraints could solve issues with discretizing the gait cycle, the virtual constraints method from robotics does not readily translate to prosthetics because of hard-to-measure quantities, like the interaction forces between the user and prosthesis socket, and prosthesis parameters which are often altered by a clinician even for a known patient. We use the simultaneous stabilization approach to design a low-order, linear time-invariant controller for ankle prostheses independent of such quantities to enforce a virtual constraint. We show in simulation that this controller produces suitable walking gaits for a simplified amputee model.
The Use of Vehicle Dynamic Response to Estimate Road Profile Input in Time Domain
Authors: Qin Yechen , Langari Reza , Gu Liang
Published: December 2014

A new method for road profile estimation in time domain with the application of vehicle system response was presented in this paper, and the problem was transformed as a system identification issue for an inverse nonlinear quarter vehicle model. Firstly, the inverse vehicle dynamic model was trained with specifically chosen white noise signal, and then eight different types of membership functions (MF) for Adaptive Neuro Fuzzy Inference System (ANFIS) were compared. Finally, the comparison of three different methods: ANFIS, Recursive Least Square (RLS) and Group Method of Data Handling (GMDH) were researched with different vehicle speeds and different road levels in the simulation part. The results showed that ANFIS is better in comparison with RLS and GMDH and this method can be further applied for vehicle system analysis.
Recursive Assembly of Multi-Layer Perceptron Neural Networks
Authors: Motato Eliot , Radcliffe Clark
Published: December 2014

The objective of this paper is to present a methodology to modularly connect Multi-Layer Perceptron (MLP) neural network models describing static port-based physical behavior. The MLP considered in this work are characterized for an standard format with a single hidden layer with sigmoidal activation functions. Since every port is defined by an input-output pair, the number of outputs of the proposed neural network format is equal to the number of its inputs. This work extends the Model Assembly Method (MAM) used to connect transfer function models and Volterra models to multi-layer perceptron neural networks.
Adaptive Suppression of High-Frequency Wide-Spectrum Vibrations With Application to Disk Drive Systems
Authors: Sun Liting , Chen Xu , Tomizuka Masayoshi
Published: December 2014

In the big-data era, requirements for storage capacity and access speed in modern Hard Disk Drive (HDD) systems are becoming more and more stringent. As the track density of HDDs increases, vibration suppression of the recording arm in HDDs is becoming more challenging. Vibrations in modern HDDs are environment/product-dependent with different frequency characteristics. Furthermore, they can occur at very high frequencies with wide spectral peaks. This paper presents an adaptive algorithm to identify and suppress these high-frequency wide-spectrum vibrations. We design a vibration-compensation controller based on an adaptive disturbance observer (DOB), and devise parameter adaptation algorithms not only for the vibration frequencies but also for the spectral peak widths of the vibration. The peak-width parameters are adaptively tuned online to maximally attenuate the vibration with minimal error amplifications at other frequencies. The proposed algorithm is verified by simulations of HDDs for the problem of suppressing high-frequency wide-spectrum vibrations.
Spider Bots: A Low Cost Platform for Testing and Validating Cooperative Control Algorithms
Authors: Price Jack , Laird Damien , Raptis Ioannis
Published: December 2014

A primary factor limiting the development, testing, and validation of decentralized algorithms for large-scale multi-robot teams is the high cost of the available systems. When a successful test necessitates that an algorithm functions on dozens or even hundreds of robots simultaneously, a low price tag on each robot is crucial. This paper presents Spider-Bots, a low cost platform for testing and validating control algorithms for multi-robot swarms. The platform is comprised of centimeter-scale mobile robots that can communicate wirelessly and interact with their environment, along with easy to use software libraries. The resulting platform was validated by testing its ability to execute and record data from three separate algorithms: Set-point navigation, object manipulation, and collision avoidance.
An Electrical Microgrid: Integration of Solar Panels, Compressed Air Storage, and a Micro-Cap Gas Turbine
Authors: Patel Shreyas M. , Freeman Paul T. , Wagner John R.
Published: December 2014

Non-renewable energy sources such as coal, oil, and natural gas are being consumed at a brisk pace while greenhouse gases contribute to atmospheric pollution. A global shift is underway toward the inclusion of renewable energy sources, such as solar and wind, for generating electrical and mechanical power. To meet this emerging demand, a solar based electrical microgrid study is underway at Clemson University. Solar energy is harvested from photovoltaic panels capable of producing 15 kW of DC power. Compressed air energy storage has been evaluated using the generated solar power to operate an electric motor driven piston compressor. The compressed air is then stored under pressure and supplied to a natural gas driven Capstone C30 MicroTurbine with attached electric power generator. The compressed air facilitates the turbine’s rotor-blade operated compression stage resulting in direct energy savings. A series of mathematical models have been developed. To evaluate the feasibility and energy efficiency improvements, the experimental and simulation results indicated that 127.8 watts of peak power was delivered at 17.5 Volts and 7.3 Amps from each solar panel. The average power generation over a 24-hour time period from 115 panels was 15 kW DC or 6 kW of AC power at 208/240 VAC and 25 Amps from the inverter. This electrical power could run a 5.2 kW reciprocating compressor for approximately 5 hours storing 1,108 kg of air at a 1.2 MPa pressure. A case study indicated that the microturbine, when operated without compressed air storage, consumed 11.2 kg of gaseous propane for 30 kW·hr of energy generation. In contrast, the microturbine operated in conjunction with solar supplied air storage could generate 50.8 kW·hr of electrical energy for a similar amount of fuel consumption. The study indicated an 8.1% efficiency improvement in energy generated by the system which utilized compressed air energy storage over the traditional approach.
Power Split Hybrid Configurations for Human-Powered Vehicles
Authors: Chen I-Ming , Li Chiao-Ting , Peng Huei
Published: December 2014

This paper presents systematic analysis and design of power split hybrid configurations using a single planetary gearset and two electric machines for human-powered vehicles. In our design methodology, the cyclist is treated as an integrated part of the powertrain, and the cyclist’s power output is augmented by the battery power, instead of being completely replaced. To obtain the optimal design, all the 12 possible power split hybrid configurations are investigated, and several performance indices, including the cyclist’s oxygen consumption, stamina reduction, and pedaling speed preference, are considered in the optimization problem to evaluate the bicycle design. The dynamic programming technique is used to solve the optimization problem. The optimal design, HyBike-i2, has the pedal connected to the carrier gear and one electric machine to the ring gear on the planetary gearset. The other electric machine and the driven wheel are connected to the sun gear. This design outperforms the normal bicycle (no power assist) and two traditional electric bicycles, and achieves substantial reduction in both the cyclist’s stamina discharge and oxygen consumption when the vehicle operates in the charge-sustaining mode.
Optimal Vehicle Motion Control to Mitigate Secondary Crashes After an Initial Impact
Authors: Kim Byung-joo , Peng Huei
Published: December 2014

Typical drivers are not ready to react to unexpected collisions from other vehicles. The initial impact can startle the driver who then fails to maintain control. Since a loss of control leads to intense skidding and undesirable lateral motions, more severe subsequent events are likely to occur. To reduce the severity of possible subsequent (secondary) crashes, this paper considers both vehicle heading angle and lateral deviation from the original driving path. The research concept here is different from today’s electronic stability control systems in that it activates the differential braking even when the magnitude of yaw rate or vehicle slip angle is very high. In addition, the lateral displacement and yaw angle with respect to the road are part of the control objective. The Linear Time Varying Model Predictive Control (LTV-MPC) method is used, with the key tire nonlinearities captured through linearization. We consider tire force constraints based on the combined-slip tire model and their dependence on vehicle motion. The computed high-level (virtual) control signals are realized through a control allocation problem which maps vehicle motion commands to tire braking forces considering constraints. Numerical simulation and analysis results are presented to demonstrate the effectiveness of the control algorithm.
Non-Invasive Fault Detection in an Axial Flow Blood Pump Used as a Ventricle Assistive Device
Authors: Rana Rohit , Schwarz Karl Q. , Kolodziej Jason R.
Published: December 2014

A Ventricular Assistive Device (VAD) is a mechanical pump used to assist the functioning of a weak heart. A catastrophic obstruction in the VAD system could cost the patient their life. This paper discusses a fault detection approach using the commercially available Jarvik 2000 Flowmaker® VAD in a closed loop circuit that incorporates the ability to alter common causes of VAD congestion. Principal Component Analysis, a data compression technique used to discover patterns in data of high dimension, is implemented using frequency analysis of the VAD’s acoustic signature. This is followed by a health classification based on Bayes theorem. The classification results indicate that this technique is accurate to a high degree in detecting three levels of obstruction in the VAD system.
The Effect of Forecasting Accuracy on the Sizing of Energy Storage
Authors: Jaworsky Christina , Turitsyn Konstantin , Backhaus Scott
Published: December 2014

The purpose of this research is to the problem of optimal sizing of energy storage required for compensation of wind farm generation variability. Using wind farm production data from the BPA, we assess the effect of forecast quality and economic dispatch timing on the size of storage and critical power rating required to nearly perfectly match the committed energy. We develop a Model-Predictive-Control (MPC) based operational model following NERC standard recommendations. Different forecasts are considered and compared from the storage sizing perspective. The results of our simulations can be fit by two simple relations, connecting the storage sizing with forecast error, wind variability, and the timescales of scheduling. A more accurate forecast reduces the storage sizing. However, diminishing returns are observed when the forecast error becomes comparable to natural wind variability within the commitment time interval. The proposed methodology can be extended to other systems with intermittent generation and controllable real or virtual storage.
Control-Oriented Drift-Flux Modeling of Single and Two-Phase Flow for Drilling
Authors: Aarsnes Ulf Jakob F. , Di Meglio Florent , Evje Steinar , Aamo Ole Morten
Published: December 2014

We present a simplified drift-flux model for gas-liquid flow in pipes. The model is able to handle single and two-phase flow thanks to a particular choice of empirical slip law. A presented implicit numerical scheme can be used to rapidly solve the equations with good accuracy. Besides, it remains simple enough to be amenable to mathematical and control-oriented analysis. In particular, we present an analysis of the steady-states of the model that yields important considerations for drilling practitioners. This includes the identification of 4 distinct operating regimes of the system, and a discussion on the occurrence of slugging in underbalanced drilling.
Optimal Discrete-Time Energy Harvesting From Infinite-Dimensional Stochastic Systems
Authors: Scruggs J. T. , Cassidy I. L.
Published: December 2014

This paper considers the optimization of discrete-time control systems for power generation from stochastically-excited linear dynamical systems, characterized by infinite-dimensional dynamics. Weiner-Hopf theory is used to determine the physical upper bound on stationary power generation. The resultant expressions for power generation do not require a finite-dimensional state-space model to be specified at any point in the analysis. However, the constraint that the controller be causal leads to the need to perform spectral factorizations on two associated power spectra. In many cases, analytical solutions to these factorizations are intractable, and approximate numerical techniques must be used. This paper makes use of subspace identification techniques for approximate spectral factorization. The concepts are illustrated in a wave energy conversion example.
Robust Control of a Low-Cost Mobile Robot Using a Neural Network Uncertainty Compensator
Authors: Arab Aliasghar , Yi Jingang , Fateh Mohammad Mahdi , Arabshahi Soroush
Published: December 2014

This paper presents a robust control design for a low-cost mobile robot under modeling uncertainties and external disturbances. We use a radial basis function neural network (RBFNN) to estimate and compensate for the model uncertainties and external disturbances. The proposed control design is model-free with guaranteed stability and good path-following performance. The RBFNN weight regulation and adaptive gains are designed based on the Lypanov method. Simulation and experimental results illustrate the design and demonstrate the strength of the proposed control applied to a nonholonomic wheeled mobile robot driven by low-cost permanent magnet dc motors without shaft encoders. The comparison results between proposed control and feedback linearization control confirm the effective role of the compensator in terms of precision, simplicity of design and computations.
Algorithmic Optimization of Inverse Kinematics Tables for High Degree-of-Freedom Limbs
Authors: Byl Katie , Byl Marten , Satzinger Brian
Published: December 2014

This work addresses the problem of resolving kinematic redundancy in legged robots, with the dual goals of maintaining a large reachable workspace and of achieving fast end effector motions in task space. In particular, for robots with four or more legs, gait planning allows for considerable flexibility in the orientation of a stance limb with respect to both body orientation and the ground. By appropriately commanding pitch, roll and yaw of the end effector as it moves relative to the body coordinate frame, one can increase the volume of space the feet can reach and thus allow the robot to negotiate larger terrain obstacles. At the same time, motions of the foot in task space should be done rapidly, given the joint velocities of the limbs. In this paper, we focus on RoboSimian, a robot with four identical limbs designed for dual use in manipulation and locomotion tasks, which was designed at Jet Propulsion Labs (JPL) for the DARPA Robotics Challenge (DRC). We present both heuristic guidelines and a novel, gradient-based algorithm for developing rules to set the inverse kinematics (IK) solution for the seven joint angles of a limb, allowing us to prescribe joint solutions rapidly through the use of an IK look-up table.
Adaptive Predictor-Based Output Feedback Control for a Class of Unknown MIMO Linear Systems: Experimental Results
Authors: Nguyen Chuong Hoang , Leonessa Alexander
Published: December 2014

Experimental results are presented to validate a recently developed adaptive output feedback controller for a general class of unknown MIMO linear systems. The control approach relies on three components, a predictor, a reference model, and a controller. Specifically, since the predictor is designed to predict the system’s output for any admissible control input, controlling the uncertain system is reduced to controlling the predictor, which is a virtual system with known dynamics and full state available. Subsequently, a full state feedback control law is designed to control the predictor output to approach the reference system, while the reference system tracks the desired trajectory while accounting for the actuator amplitude and rate saturation constraints. Ultimately, the control objective of driving the actual system output to track the desired trajectories is achieved by showing that the system output, the predictor output, and the reference system trajectories all converge to each other. Theorems and the step-by-step implementation of the control strategy are presented. Finally, the control’s efficacy is illustrated by a real time implementation of the proposed algorithm on an actual helicopter test bed.
Battery State of Health Monitoring by Side Reaction Current Density Estimation via Retrospective-Cost Subsystem Identification
Authors: Zhou Xin , Ersal Tulga , Stein Jeffrey L. , Bernstein Dennis S.
Published: December 2014

This paper introduces a method to estimate battery state of health (SoH) via health-relevant electrochemical features. Battery state of health estimation is a critical part of battery management because it allows for balancing the trade-off between maximizing performance and minimizing degradation. In this paper, a health-relevant electrochemical feature, the side reaction current density, is used as the indicator of battery SoH. An estimation algorithm is required due to the unavailability of the side reaction current density via noninvasive methods. In this paper, Retrospective-Cost Subsystem Identification (RCSI) is used to estimate the side reaction current density via identification of an unknown battery health subsystem that generates the side reaction current density. Simulation results are provided for constant current charge and discharge cycles with different C rates. A current profile for an electric vehicle (EV) going through Urban Dynamometer Driving Schedule (UDDS) cycles is also used as the excitation signal during estimation. The simulations show promising results in battery health dynamic identification and side reaction current density estimation with RCSI.
A Case Study in Control Methods for Active Magnetic Bearings
Authors: Pesch Alexander H. , Hanawalt Stephen P. , Sawicki Jerzy T.
Published: December 2014

Active magnetic bearings (AMBs) provide support to rotating machinery through magnetic forces which are regulated through active feedback control. As AMBs continue to establish themselves as a proven technology, many classical and modern techniques are being employed to address the design of the control law. The current work studies three of the controller design techniques which are common in the literature for AMB applications: PID, LQG, and μ-synthesis. A controller is designed for an AMB system using each of the three techniques. Details of the design processes are given and the resulting controllers are compared. Finally, the controllers are implemented on the experimental system and the closed-loop characteristics are measured and evaluated. This work provides a common case study to demonstrate the strengths and weaknesses of PID, LQG, and μ-synthesis control methodologies as applied to a specific AMB system.
A Framework for Autonomous Vehicles With Goal Inference and Task Allocation Capabilities to Support Peer Collaboration With Human Agents
Authors: Liu Chang , Liu Shih-Yuan , Carano Elena L. , Hedrick J. Karl
Published: December 2014

This paper proposes a framework for autonomous vehicles to collaborate with human agents as peers in task completion scenarios. In this framework, the autonomous vehicles utilize the Bayesian inference method to determine human intention. An optimal task allocation that minimizes the mission completion time while respecting the intention of the human agents is developed using the Mixed Integer Linear Programming (MILP) method. The proposed framework can accommodate different levels of suboptimality in human agents’ behavior by adjusting a tunable parameter in the inference model. The effectiveness of the framework in facilitating human-autonomous vehicle collaboration is demonstrated through simulations.
Differential Diagnostics for Lithium Ion Battery Cells Connected in Series
Authors: Safi Jariullah , Anstrom Joel , Brennan Sean , Fathy Hosam K.
Published: December 2014

This paper presents a new method for estimating the capacity of a lithium ion battery cell in the presence of a reference cell — the parameters of which are well characterized — in series with it. The method assumes that both cells are cycled using the same current trajectory starting from the same state of charge (e.g. fully charged). Voltage measurements for both cells as well as current measurements for the series string constitute the input to a nonlinear least squares minimization problem. The goal of this problem is to estimate the capacity of the cell given the difference between its voltage and that of the reference cell. We refer to this as the differential estimation problem, and use Monte Carlo simulation to compare it to the more traditional approach of estimating the capacity of each cell in a battery string independently using its current/voltage measurements. Two key conclusions emerge from this simulation. Compared to traditional estimation, differential estimation results in capacity estimates whose variance is (i) twice as sensitive to voltage measurement noise but (ii) significantly less sensitive to current measurement noise. This makes differential estimation more appealing for battery packs with high current measurement noise and low voltage measurement noise.
A Low-Order HCCI Model Extended to Capture SI-HCCI Mode Transition Data With Two-Stage Cam Switching
Authors: Gorzelic Patrick , Shingne Prasad , Martz Jason , Stefanopoulou Anna , Sterniak Jeff , Jiang Li
Published: December 2014

A low-order homogeneous charge compression ignition (HCCI) combustion model to support model-based control development for spark ignition (SI)/HCCI mode transitions is presented. Emphasis is placed on mode transition strategies wherein SI combustion is abruptly switched to recompression HCCI combustion through a change of the cam lift and opening of the throttle, as is often employed in studies utilizing two-stage cam switching devices. The model is parameterized to a steady-state dataset which considers throttled operation and significant air-fuel ratio variation, which are pertinent conditions to two-stage cam switching mode transition strategies. Inspection and simulation of transient SI to HCCI (SI-HCCI) mode transition data shows that the extreme conditions present when switching from SI to HCCI can cause significant prediction error in the combustion performance outputs even with the model’s adequate steady-state fit. When a correction factor related to residual gas temperature is introduced to account for these extreme conditions, it is shown that the model reproduces transient performance output time histories in SI-HCCI mode transition data. The model is thus able to capture steady-state data as well as transient SI-HCCI mode transition data while maintaining a low-order cycle to cycle structure, making it tractable for model-based control of SI-HCCI mode transitions.
RIM Propeller for Micro Autonomous Underwater Vehicles
Authors: Kim David Donghyun , Wu You , Noel Antoine , Youcef-Toumi Kamal
Published: December 2014

Micro autonomous underwater vehicles (AUVs) need small-scale, powerful and safe propulsion systems especially when they are performing missions in pipes and other confined environments. However, the most conventional propulsion systems do not satisfy all three requirements: small, powerful and safe. A micro propulsion system meeting those requirements are developed based on the RIM propeller concept. It is compact and powerful; the complete motor-propeller assembly is 33mm in diameter, 12mm in depth and 16g in weight, and it is capable of producing 0.4N thrust in static water given a 7.1W power input. The paper presents the design, manufacturing and integration of the micro RIM propeller in an AUV.
Energy Management and Control of a Hybrid Electric Vehicle With an Integrated Low Temperature Combustion (LTC) Engine
Authors: Solouk Ali , Shahbakhti Mahdi , Mahjoob Mohammad J.
Published: December 2014

Low Temperature Combustion (LTC) provides a promising solution for clean energy-efficient engine technology which has not yet been utilized in Hybrid Electric Vehicle (HEV) engines. In this study, a variant of LTC engines, known as Homogeneous Charge Compression Ignition (HCCI), is utilized for operation in a series HEV configuration. An experimentally validated dynamic HCCI model is used to develop required engine torque-fuel consumption data. Given the importance of Energy Management Control (EMC) on HEV fuel economy, three different types of EMCs are designed and implemented. The EMC strategies incorporate three different control schemes including thermostatic Rule-Based Control (RBC), Dynamic Programming (DP), and Model Predictive Control (MPC). The simulation results are used to examine the fuel economy advantage of a series HEV with an integrated HCCI engine, compared to a conventional HEV with a modern Spark Ignition (SI) engine. The results show 12.6% improvement in fuel economy by using a HCCI engine in a HEV compared to a conventional HEV using a SI engine. In addition, the selection of EMC strategy is found to have a strong impact on vehicle fuel economy. EMC based on DP controller provides 15.3% fuel economy advantage over the RBC in a HEV with a HCCI engine.
Dynamics and Control of Dual-Hoist Cranes Moving Triangular Payloads
Authors: Miller Alexander S. , Sarvepalli Padma , Singhose William
Published: December 2014

Certain heavy-lifting applications require the coordinated movement of multiple cranes. Such tasks dramatically increase the complexity of crane operation, especially when the payload has a non-uniform shape. This paper studies the dynamic behavior of a dual-hoist bridge crane moving triangular payloads. Simulations and experiments are used to develop an understanding of the dynamic response of the system. Various inputs and system configurations are analyzed, and important response characteristics are highlighted.
Design and Experimental Validation of a Virtual Vehicle Control Concept for Testing Hybrid Vehicles Using a Hydrostatic Dynamometer
Authors: Du Zhekang , Li Perry Y. , Cheong Kai Loon , Chase Thomas R.
Published: December 2014

An approach to control a hydrostatic dynamometer for the Hardware-In-the-Loop (HIL) testing of hybrid vehicles has been developed and experimentally tested. The hydrostatic dynamometer used, which is capable of regeneration, was specifically designed and built in-house to evaluate the fuel economy and control strategy of a hydraulic hybrid vehicle. The control challenge comes from the inertia of the dynamometer being only 3% of that of the actual vehicle so that the dynamometer must apply, in addition to any drag torques, acceleration/deceleration torques related to the difference in inertias. To avoid estimating the acceleration which would be a non-causal operation, a virtual vehicle concept is introduced. The virtual vehicle model generates a reference speed profile which represents the behavior of the actual vehicle if driven on the road. The dynamometer control problem becomes one of enabling the actual vehicle-dyno shaft to track the speed of the virtual vehicle, instead of directly applying a desired torque. A feedback/feedforward controller was designed based upon an experimentally validated dynamic model of the dynamometer. The approach was successfully tested on a power-split hydraulic hybrid vehicle with acceptable speed and torque tracking performance.
Inversion-Based Optimal Output Transition With Input and Time Constraints for Non-Minimum Phase Linear System
Authors: Liu Jiangbo , Zou Qingze
Published: December 2014

In this article, the problem of trajectory design and tracking of non-periodic tracking-transition switching for non-minimum phase linear systems is considered. Such a trajectory design and tracking problem exists in applications such as nanomanipulation, robotic operation, and hard-disk control, where the whole trajectory consists of tracking sessions with the application-specified desired trajectory to be tracked, and transition sessions with the output trajectory to be designed. This problem becomes challenging as multiple control objectives need to be achieved. The proposed approach extends the previous work that attained smooth output transition and smooth tracking-transition switching to further achieve amplitude-constrained input-energy minimization and transition time minimization. First, the constrained input optimization problem is converted to an unconstrained input minimization problem. Then the optimal output and input are obtained by using an improved conjugate gradient method. Finally, the total transition time is further minimized via one dimensional search. The proposed approach is illustrated through a simulation example in probe-based nanomanipulation utilizing a piezoelectric actuator.
Inverse Kinematics and Extended Kalman Filter Based Motion Tracking of Human Limb
Authors: Isaac Benson , Kumar Manish , Huang Samuel H. , Humpert Daniel
Published: December 2014

This paper addresses the problem of motion tracking of human skeleton system using non-invasive vision based sensors. The proposed approach combines synergistic paradigms of image processing, kinematics of rigid bodies and Extended Kalman Filtering scheme to estimate the motion of a human limb system. This approach solely depends on the measurement obtained from the vision sensors without involving any wearable or inertial sensors to measure the motion parameters. In this paper we propose fusion of two filtering schemes — the optical flow equations applied to raw images obtained from the Microsoft Kinect and extended Kalman filter for human skeleton considered as a system of kinematic linkages. The strategy proposed in this paper yields near optimal results as is demonstrated with the help of experiments performed using the Microsoft Kinect sensor and compared using accurate tracks obtained from 24-Camera Optitrack motion capture system.
Haptic Control in Physical Human-Robot Interaction Based on Support Vector Machine Classification of Muscle Activity: A Preliminary Study
Authors: Moualeu Antonio , Ueda Jun
Published: December 2014

This study aims to develop methods to increase information available to a haptic device about a human operator during physical human-robot interaction. Physical contact between a robot and human operator establishes a coupled system with stability and performance characteristics partly dependent on interaction port impedance behavior. Operator impedance is estimated in this research based on changes in arm muscle activity, recorded through electromyographic (EMG) signals. A switching impedance controller employing a Support Vector Machine (SVM) classifier for operator state estimation is used in an interaction system with a one degree-of-freedom haptic device. Results from performance (e.g. speed, accuracy) trials investigating a stochastic approach to position control are presented in comparison to other standard approaches. This research serves a basis for the exploration of advanced control tools and ultimately developing a novel human-robot interface. Applications for such research include interaction with robot co-workers (e.g. power-assisting devices) in industrial settings.
An Equivalent Plant Representation for Unknown Control Systems
Authors: Mohsenizadeh Daniel N. , Keel Lee H. , Bhattacharyya Shankar P.
Published: December 2014

This paper proposes a new method to the design of a controller to be embedded at a prescribed location in an otherwise unknown complex and multiple-loop Linear Time-Invariant (LTI) control system. The questions that arise naturally are: Will a controller proposed for this location stabilizes the overall system and, if so, what stability margins and response can be obtained? We address these questions by constructing an equivalent single-loop frequency domain representation of the original unknown complex system. This equivalent plant construction can be accomplished by a small set of frequency response measurements.
Atomic layer deposition of titanium sulfide and its application in extremely thin absorber solar cells
Authors: Mahuli Neha , Sarkar Shaibal K.
Published: December 2014

Atomic layer deposition (ALD) of TiS2 is investigated with titanium tetrachloride and hydrogen sulfide precursors. In-situ quartz crystal microbalance and ex-situ x-ray reflectivity measurements are carried out to study self-limiting deposition chemistry and material growth characteristics. The saturated growth rate is found to be ca. 0.5 Å/cycle within the ALD temperature window of 125–200 °C. As grown material is found poorly crystalline. ALD grown TiS2 is applied as a photon harvesting material for solid state sensitized solar cells with TiO2 as electron transport medium. Initial results with Spiro-OMeTAD as hole conducting layer show ca. 0.6% energy conversion efficiency under 1 sun illumination.
Laboratory measurements of high-frequency, acoustic broadband backscattering from sea ice and crude oil
Authors: Bassett Christopher , Lavery Andone C. , Maksym Ted , Wilkinson Jeremy P.
Published: December 2014

Recent decreases in summer sea ice cover are spurring interest in hydrocarbon extraction and shipping in Arctic waters, increasing the risk of an oil spill in ice covered waters. With advances in unmanned vehicle operation, there is an interest in identifying techniques for remote, underwater detection of oil spills from below. High-frequency (200–565 kHz), broadband acoustic scattering data demonstrate that oil can be detected and quantified under laboratory grown sea ice and may be of use in natural settings. A simple scattering model based on the reflection coefficients from the interfaces agrees well with the data.
Chapter 4 Comprehensive School Physical Activity Programs: Characteristics of Trained Teachers
Authors: Centeio Erin E. , Erwin Heather , Castelli Darla M.
Published: December 2014

As public health concerns about physical inactivity and childhood obesity continue to rise, researchers are calling for interventions that comprehensively lead to more opportunities to participate in physical activity (PA). The purpose of this study was to examine the characteristics and attitudes of trained physical education teachers during the implementation of a Comprehensive School Physical Activity Program at the elementary level. Using a collective case study design, interviews, observations, field notes, open-ended survey questions, and an online forum monitoring guided the interpretation of teacher perceptions and development of emergent themes. Qualitative data analysis was conducted for each individual teacher and then across the ten teachers which produced four major themes: (a) Leading the Charge: Ready, Set, Go!, (b) Adoption versus Adaptation: Implementation Varies, (c) Social Media’s Place in the Professional Development (PD) Community, and (d) Keys to Successful Implementation. It can be concluded that, based on these findings, elementary physical education teachers are ready and willing to implement CSPAP. Key factors that may influence this implementation are discussed.
Promoter architecture dictates cell-to-cell variability in gene expression
Authors: Jones Daniel L. , Brewster Robert C. , Phillips Rob
Published: December 2014

Variability in gene expression among genetically identical cells has emerged as a central preoccupation in the study of gene regulation; however, a divide exists between the predictions of molecular models of prokaryotic transcriptional regulation and genome-wide experimental studies suggesting that this variability is indifferent to the underlying regulatory architecture. We constructed a set of promoters in
Escherichia coli
in which promoter strength, transcription factor binding strength, and transcription factor copy numbers are systematically varied, and used messenger RNA (mRNA) fluorescence in situ hybridization to observe how these changes affected variability in gene expression. Our parameter-free models predicted the observed variability; hence, the molecular details of transcription dictate variability in mRNA expression, and transcriptional noise is specifically tunable and thus represents an evolutionarily accessible phenotypic parameter.
Direct observation of closed magnetic flux trapped in the high-latitude magnetosphere
Authors: Fear R. C. , Milan S. E. , Maggiolo R. , Fazakerley A. N. , Dandouras I. , Mende S. B.
Published: December 2014

The structure of Earth’s magnetosphere is poorly understood when the interplanetary magnetic field is northward. Under this condition, uncharacteristically energetic plasma is observed in the magnetotail lobes, which is not expected in the textbook model of the magnetosphere. Using satellite observations, we show that these lobe plasma signatures occur on high-latitude magnetic field lines that have been closed by the fundamental plasma process of magnetic reconnection. Previously, it has been suggested that closed flux can become trapped in the lobe and that this plasma-trapping process could explain another poorly understood phenomenon: the presence of auroras at extremely high latitudes, called transpolar arcs. Observations of the aurora at the same time as the lobe plasma signatures reveal the presence of a transpolar arc. The excellent correspondence between the transpolar arc and the trapped closed flux at high altitudes provides very strong evidence of the trapping mechanism as the cause of transpolar arcs.
U.S. fusion effort melts down
Authors: Cho Adrian
Published: December 2014

Scientific community battles with its federal office.
Celebrated biodiversity institute faces financial crisis
Authors: Wade Lizzie
Published: December 2014

New government rethinks plan to take over INBio's money-losing theme parks.
MAVS, cGAS, and endogenous retroviruses in T-independent B cell responses
Authors: Zeng Ming , Hu Zeping , Shi Xiaolei , Li Xiaohong , Zhan Xiaoming , Li Xiao-Dong , Wang Jianhui , Choi Jin Huk , Wang Kuan-wen , Purrington Tiana , Tang Miao , Fina Maggy , DeBerardinis Ralph J. , Moresco Eva Marie Y. , Pedersen Gabriel , McInerney Gerald M. , Hedestam Gunilla B. Karlsson , Chen Zhijian J. , Beutler Bruce
Published: December 2014

Multivalent molecules with repetitive structures including bacterial capsular polysaccharides and viral capsids elicit antibody responses through B cell receptor (BCR) crosslinking in the absence of T cell help. We report that immunization with these T cell–independent type 2 (TI-2) antigens causes up-regulation of endogenous retrovirus (ERV) RNAs in antigen-specific mouse B cells. These RNAs are detected via a mitochondrial antiviral signaling protein (MAVS)–dependent RNA sensing pathway or reverse-transcribed and detected via the cGAS-cGAMP-STING pathway, triggering a second, sustained wave of signaling that promotes specific immunoglobulin M production. Deficiency of both MAVS and cGAS, or treatment of MAVS-deficient mice with reverse transcriptase inhibitors, dramatically inhibits TI-2 antibody responses. These findings suggest that ERV and two innate sensing pathways that detect them are integral components of the TI-2 B cell signaling apparatus.
What I cannot create, I do not understand
Authors: Lupas Andrei N.
Published: December 2014

A designed protein transports ions across a membrane

[Also see Report by

Joh
et al.

]