bluuebunny/crossref_metadata_2025 huggingface dataset:
Accelerated Evaluation of Automated Vehicles in Lane Change Scenarios
Authors: Zhao Ding , Peng Huei , Lam Henry , Bao Shan , Nobukawa Kazutoshi , LeBlanc David J. , Pan Christopher S.
Published: January 2016

It is important to rigorously and comprehensively evaluate the safety of Automated Vehicles (AVs) before their production and deployment. A popular AV evaluation approach is Naturalistic-Field Operational Test (N-FOT) which tests prototype vehicles directly on public roads. Due to the low exposure to safety-critical scenarios, N-FOTs is time-consuming and expensive to conduct. Computer simulations can be used as an alternative to N-FOTs, especially in terms of generating motions of the surrounding traffic. In this paper, we propose an accelerated evaluation approach for AVs. Human-controlled vehicles (HVs) were modeled as disturbance to AVs based on data extracted from the Safety Pilot Model Deployment Program. The cut-in scenarios are generated based on skewed statistics of collected human driver behavior, which amplifies riskier testing scenarios while reserves its statistical information so that the safety benefits of AV in non-accelerated cases can be accurately estimated. An AV model based on a production vehicle was tested. Results show that the proposed method can accelerate the evaluation process by at least 100 times.
Battery Thermal Management of Electric Vehicles: An Optimal Control Approach
Authors: Masoudi Yasaman , Mozaffari Ahmad , Azad Nasser L.
Published: January 2016

The main goal of the current investigation is to evaluate the potential of the optimal control techniques to improve the quality of battery thermal management (BTM) in electric vehicles (EVs). The BTM is of profound importance in EVs, where battery is the sole power source and any unexpected change in the battery temperature could dramatically affect the vehicle performance and its driving range. As a result, the battery temperature should be maintained within a specific range to lead to the best vehicle performance. Despite the obvious importance of this issue, there exist rare reports in the literature addressing the design of optimal controllers for BTM of EVs. Here, the authors intend to apply and compare two controllers to solve this problem for an EV: an optimal controller designed upon dynamic programming (DP) and a proportional integral-derivative (PID) controller. The results indicate that by using DP, a less amount of the battery power will be demanded, and therefore, the vehicle’s driving range can be increased.
Analysis of Stability and Bifurcation of an Asymmetrical Rotor
Authors: Shahgholi Majid , Khadem S. E. , Asgarisabet Mahsa
Published: January 2016

The effect of shaft and disk asymmetry on the harmonic resonances of a rotor system with the in-extensional nonlinearity and large amplitude are investigated. Two rotor systems, one of which has been comprised of a symmetrical shaft and an asymmetrical disk (SA), and the other one has been comprised of an asymmetrical shaft and an asymmetrical disk (AA) are investigated. The shaft in the AA rotor has unequal mass moments of inertia and flexural rigidities in the direction of principal axes. Also, in the AA system the rigid disk is asymmetric with unequal mass moments of inertia. The equations of motion are derived by the Hamiltonian principle. The stability and bifurcations are obtained using the multiple scales method. The influences of asymmetry of shaft, asymmetry of disk, inequality between two eccentricities corresponding to the principal axes, disk position and external damping on the stability and bifurcations of SA and AA rotors are investigated. The results achieved from multiple scales method show a good agreement with those of numerical simulations.
Experimental Verification of Dynamic Contour Error Estimation for High-Precision Contouring of Two-Axis Servo-Systems
Authors: Ghaffari Azad , Ulsoy A. Galip
Published: January 2016

High-precision contouring is important in machining. A practically proven method to improve contouring precision is adding a cross-coupling algorithm, which acts on contour error, to the existing position control loops. The contour error estimate (CEE) significantly affects performance of the cross-coupling algorithm. Conventional CEE methods rely on static single-point algorithms. A Newton-based CEE algorithm which effectively improves CEE and dramatically reduces contouring error has recently been proposed [22]. In this paper, instead of a separate cross-coupling control it is proposed to modify the position control loops, in this case integral sliding mode control, to incorporate the contour error in the control loop. Various experiments to identify the effect of 1) number of required iterations of the Newton-based CEE, 2) reference feedrate and curvature, and 3) sharp corners on overall performance of the proposed cross-coupling algorithm are reported. The experimental setup includes a two-axis servo-system. Control and estimation algorithms are implemented on two sbRIO 9632 from National Instruments.
An MPC Algorithm With Combined Speed and Steering Control for Obstacle Avoidance in Autonomous Ground Vehicles
Authors: Liu Jiechao , Jayakumar Paramsothy , Stein Jeffrey L. , Ersal Tulga
Published: January 2016

This article presents a model predictive control based obstacle avoidance algorithm for autonomous ground vehicles in unstructured environments. The novelty of the algorithm is the simultaneous optimization of speed and steering without a priori knowledge about the obstacles. Obstacles are detected using a planar light detection and ranging sensor and a multi-phase optimal control problem is formulated to optimize the speed and steering commands within the detection range. Acceleration capability of the vehicle as a function of speed, and stability and handling concerns such as tire lift-off are taken into account as constraints in the optimization problem, whereas the cost function is formulated to navigate the vehicle as quickly as possible with smooth control commands. Thus, a safe and quick navigation is enabled without the need for a preloaded map of the environment. Simulation results show that the proposed algorithm is capable of navigating the vehicle through obstacle fields that cannot be cleared with steering control alone.
A Robotic Vehicle for Aquatic Environmental Monitoring
Authors: Laut Jeffrey , High Ben , Nov Oded , Porfiri Maurizio
Published: January 2016

Environmental monitoring is critical for assessing and protecting our natural resources. Robotics can greatly benefit this field be enabling rapid assessment of large areas with minimal human supervision. Here, we describe an aquatic mobile robot for data collection in a polluted waterway. The robot is part of an environmental monitoring project known as “Brooklyn Atlantis,” and collects water quality data and images within the Gowanus Canal in Brooklyn, NY. Water quality is analyzed offline, while images are classified using citizen science through a web-based interface. To provide an added degree of interactivity to the participants of the project, an automated pan-tilt camera rig is developed, capable of providing 360° panorama photos that can be manipulated by a user. Beyond data collection, the robot serves as a useful tool for outreach and directly engaging the local community in science-based activities.
Vibration Suppression Based on Adaptive Feedforward Control With Infinite Impulse Response Filter
Authors: Zhou Shiying , Tomizuka Masayoshi
Published: January 2016

This paper presents adaptive feedforward control for vibration suppression based on an infinite impulse response (IIR) filter structure. The vibration signal and the output signal are available for the algorithm to adaptively update the parameters of the vibration transmission path (VTP) dynamics. Two designs for parameter adaptation are proposed. They provide different methods to get the necessary signals for parameter adaptation of the IIR filter which is different from the conventional finite impulse response (FIR) filter adaptation design. Performance of the proposed designs is compared with the conventional Filtered-x Least Mean Square (FxLMS) method on a hard disk drive (HDD) benchmark problem. The simulation results show that the proposed designs have smaller 3σ value and peak to peak value at steady state.
Elevated Temperatures Can Extend the Life of Lithium Iron Phosphate Cells in Hybrid Electric Vehicles
Authors: Tanim Tanvir R. , Rahn Christopher D. , Legnedahl Niklas
Published: January 2016

This study investigates the effects of elevated temperature on commercially available high power graphite/LiFePO4 cells using a temperature dependent, electrolyte enhanced, single particle model (ESPM-T) coupled with a Solid Electrolyte Interphase (SEI) layer growth aging model. The ESPM-T is capable of simulating up to 25C and 10 sec charge-discharge pulses within a 35–65% SOC window and 25°C to 40°C temperature range with less than 1% voltage error, so it is suitable for hybrid electric vehicle (HEV) applications. The aging model is experimentally validated with an aggressive HEV cycle running for 4 months with less than 1% error. Instead of defining battery End of Life (EOL) as an arbitrary percent of capacity loss, we use the cycle number when the battery voltage hits 3.6V/2V (maximum/minimum) voltage limits. This is the practical limit of operation without reduced performance. Simulations show that operating cells at 35°C increases their life by 45% compared to room temperature operation. If the cell temperature is increased stepwise, then battery life is increased 85% more with a 50°C cell temperature at EOL. Battery initial size can be reduced by 24% using this temperature set-point strategy.
Automatic Identification of Closed-Loop Wind Turbine Dynamics via Genetic Programming
Authors: La Cava William , Danai Kourosh , Lackner Matthew , Spector Lee , Fleming Paul , Wright Alan
Published: January 2016

Wind turbines are nonlinear systems that operate in turbulent environments. As such, their behavior is difficult to characterize accurately across a wide range of operating conditions by physically meaningful models. Customarily, data-based models of wind turbines are defined in ‘black box’ format, lacking in both conciseness and physical intelligibility. To address this deficiency, we identify models of a modern horizontal-axis wind turbine in symbolic form using a recently developed symbolic regression method. The method used relies on evolutionary multi-objective optimization to produce succinct dynamic models from operational data without ‘a priori’ knowledge of the system. We compare the produced models with models derived by other methods for their estimation capacity and evaluate the tradeoff between model intelligibility and accuracy. Several succinct models are found that predict wind turbine behavior as well as or better than more complex alternatives derived by other methods.
Inertia-Driven Controlled Passive Actuation
Authors: Dresscher Douwe , de Vries Theo J. A. , Stramigioli Stefano
Published: January 2016

A serious problem with using electrical actuators in legged locomotion is the significant energy loss. For this reason, we propose and analyse an alternative means of actuation: Controlled Passive Actuation. Controlled Passive Actuation aims at reducing the energy flow through electric actuators by actuating with a combination of an energy storage element and a Continuously Variable Transmission.

In this work, we present a method where we apply a Continuously Variable Transmission with a storage element in the form of a mass to change the state of another mass (“the load”). An abstraction layer is created to abstract the inertia-driven Controlled Passive Actuation to a source of effort, a force actuator. On this abstracted system, feedback control can be applied to achieve control goals such as path tracking.

With simulations and experiments, we show that inertia-driven Controlled Passive Actuation can be used to control the state of an (inertial) load. The experimental results show that the performance of the system is affected by the internal dynamics and limited rate of change of the transmission ratio of the Continuously Variable Transmission.
A Simplified Gas-Liquid Flow Model for Kick Mitigation and Control During Drilling Operations
Authors: Aarsnes Ulf Jakob F. , Ambrus Adrian , Karimi Vajargah Ali , Aamo Ole Morten , van Oort Eric
Published: January 2016

Real-time estimation of annular pressure profile and formation pressure is crucial for the execution and planning of a well control operation, especially when drilling formations with narrow pore and fracture pressure margins. A simple transient multi-phase simulator, capable of accurately representing gas and liquid dynamics while minimizing complexity and computational requirements, is highly desirable for real-time kick mitigation and control applications. Such a simulator is presented here in the form of a coupled ODE-PDE model composed of a first order ODE and a first order hyperbolic PDE. This model is shown to retain the dominating two-phase dynamics encountered during gas kick incidents. As a particular application, we demonstrate the use of the model in design of switched control algorithms for kick handling in a Managed Pressure Drilling setting. A Recursive Least Squares algorithm is employed for estimation of unknown model parameters.
Three-Dimensional Modeling and Experimental Verification of Off-Centered Crane Lifts
Authors: Garcia Anthony , Singhose William , Ferri Aldo
Published: January 2016

When cranes lift heavy payloads off the ground, the payload may slide or swing sideways unexpectedly. This dangerous motion occurs when the payload is not directly beneath the overhead suspension point of the hoist cable. Given that cable suspension points are usually tens of feet, and perhaps hundreds of feet above the payload, it is very difficult for crane operators to know if the hoist cable is perfectly vertical before they start to lift the payload off the ground. Inevitably, some horizontal motion of the payload will occur at lift off. If an off-center lift creates substantial horizontal motion, then it can create significant hazards for the human operators, the crane, the payload, and the surrounding environment. This paper develops a three-dimensional dynamic model of off-centered lifts. The accuracy of the model is experimentally investigated using a 10-ton bridge crane.
Design of an Adaptive Singularity-Free Control Moment Gyroscope (ASCMG) Cluster for Spacecraft Attitude Control
Authors: Viswanathan Sasi Prabhakaran , Sanyal Amit K.
Published: January 2016

Spacecraft attitude control using an Adaptive Singularity-free Control Moment Gyroscope (ASCMG) cluster design for internal actuation is presented. A complete dynamics model is derived using the principles of variational mechanics, relaxing some common assumptions made in prior literature on control moment gyroscopes. These assumptions include perfect axisymmetry of the rotor and gimbal structures, and perfect alignment of the centers of mass of the gimbal and the rotor. The resulting dynamics display complex nonlinear coupling between the internal degrees of freedom associated with the CMG and the spacecraft base body’s rotational degrees of freedom in the absence of these assumptions. This dynamics model is further generalized to include the effects of multiple CMGs placed in the spacecraft bus, and sufficient conditions for non-singular CMG cluster configurations are obtained. General ideas on control of the angular momentum of the spacecraft using changes in the momentum variables of a finite number of CMGs, are provided. A control scheme using a finite number of CMGs in the absence of external torques and when the total angular momentum of the spacecraft is zero, is presented. The dynamics model of the spacecraft with a finite number of CMGs is then simplified under the assumption that the rotor is axisymmetric, in which case it is shown that singularities are avoided. As an example, the case of three CMGs with axisymmetric rotors, placed in a tetrahedron configuration inside the spacecraft, is considered. The control scheme is then numerically implemented using a geometric variational integrator and the results confirm the singularity-free property and high control authority of the ASCMG cluster. Moreover, as rotor misalignments are addressed in the dynamics model, the ASCMG cluster can adapt to them without requiring hardware changes.
Adaptive RGB-D Visual Odometry for Mobile Robots: An Experimental Study
Authors: Anderson J. Wesley , Fabian Joshua R. , Clayton Garrett M.
Published: January 2016

In this paper, experiments are presented in support of an adaptive color-depth (RGB-D) camera-based visual odometry algorithm. The goal of visual odometry is to estimate the egomotion of a robot using images from a camera attached to the robot. This type of measurement can be extremely useful when position sensor information, such as GPS, in unavailable and when error from other motion sensors (e.g., wheel encoders) is inaccurate (e.g., due to wheel slip). In the presented method, visual odometry algorithm parameters are adapted to ensure that odometry measurements are accurate while also considering computational cost. In this paper, live experiments are performed that show the feasibility of implementing the proposed algorithm on small wheeled mobile robots.
Performance Evaluation of an Extended Kalman Filter for State Estimation of a Pseudo-2D Thermal-Electrochemical Lithium-Ion Battery Model
Authors: Zhao Shi , Bizeray Adrien M. , Duncan Stephen R. , Howey David A.
Published: January 2016

Fast and accurate state estimation is one of the major challenges for designing an advanced battery management system based on high-fidelity physics-based model. This paper evaluates the performance of a modified extended Kalman filter (EKF) for on-line state estimation of a pseudo-2D thermal-electrochemical model of a lithium-ion battery under a highly dynamic load with 16C peak current. The EKF estimation on the full model is shown to be significantly more accurate (< 1% error on SOC) than that on the single-particle model (10% error on SOC). The efficiency of the EKF can be improved by reducing the order of the discretised model while maintaining a high level of accuracy. It is also shown that low noise level in the voltage measurement is critical for accurate state estimation.
Combined Input Shaping and Feedback Control of a Double-Pendulum System Subject to External Disturbances
Authors: Mar Robert , Goyal Anurag , Nguyen Vinh , Yang Tianle , Singhose William
Published: January 2016

A control system combining input shaping and feedback is applied to a double-pendulum bridge crane subjected to external disturbances. The external disturbances represent naturally occurring forces, such as gusting winds. The proposed control method achieves fast point-to-point response similar to open-loop input-shaping control. It also minimizes transient deflections and disturbance-induced residual swing using the feedback control. Effects of parameters such as the mass ratio of the double-pendulum, suspension length ratio, and the traveled distance were studied via numerical simulation and hardware experiments. The controller effectively suppresses the disturbances and is robust to modeling uncertainties and task variations.
Effect of Parallel Compliance on Stability of Robotic Hands With Series Elastic Actuators
Authors: Rao Prashant , Niehues Taylor D. , Deshpande Ashish D.
Published: January 2016

Compliance is a key requirement for safe interactions with the environment for any robot. It has been well established that the human body exploits various arrangements of compliance such as series compliance (musculo-tendon units) and parallel compliance (joint capsules and ligament complex) to achieve robust and graceful interaction with the environment. Mechanical compliance can be similarly arranged in robotic joints in series or parallel to actuators. The effects of such arrangements on the closed loop properties of robotic joints such as stability, disturbance rejection and tracking performance have been analyzed separately, but their combined effects have not been studied. We present a detailed analysis on the combined effects of series and parallel arrangements of compliance on low inertia robotic joints. Our analysis shows the stability limitations of achievable joint stiffness due to series compliance and the subsequent increase in the stable upper limit of achievable joint stiffness by addition of parallel compliance. We provide guidelines towards designing compliance to improve the stability and performance of low-inertia robotic joints, which can be applied to the improvement of robotic hands performing grasping and manipulation tasks. We validate our analysis by means of an experimental platform and discuss the various characteristics and the effects of both arrangements of compliance on robotic hands.
Flight Formation of Quad-Copters in Presence of Dynamic Obstacles Using Mixed Integer Linear Programming
Authors: Radmanesh Mohammadreza , Nemati Alireza , Sarim Mohammad , Kumar Manish
Published: January 2016

This paper proposes the implementation of Mixed Integer Linear Programming (MILP) for efficient path planning of UAVs in various flight formations. The Unmanned Aerial Vehicles (UAVs) taking part in a cooperative flight are assumed to be equipped with Automatic Dependent Surveillance Broadcast (ADS-B) which enables sharing the flight information with neighboring aircrafts. The design and implementation of the flight formation algorithm have been carried out for a general case, such that multiple UAVs with arbitrarily geographically located base stations can take part in the formation flight and collision avoided path planning. The paper formulates the problem of path of planning in the framework of MILP and proposes a cost function that minimizes time and energy consumption. The performance of the proposed algorithm has been verified via a number of simulations carried out using different scenarios.
Modeling of Coupled Axial and Torsional Motions of a Drilling System
Authors: Ma Zheren , Chen Dongmei
Published: January 2016

During drilling operations, rock-bit interactions may cause a wide range of undesirable system vibrations. The induced vibrations subsequently reduce drilling efficiency and increase fatigue loads acting on drill bit. In this paper, a coupled torsional and axial drilling model is proposed. It can be used to predict the vibrations including bit bounce and stick-slip. Instead of using finite element (FEM) approach, the drill pipe is accurately modeled based on wave propagation theory. This results in time-delay equations in time domain and significantly reduces the computational complexity associated with FEM. The axial and torsional motions are coupled by bit-rock interactions. Different rock-bit interaction conditions are considered based on bit rotation and contact with formation. Simulations are conducted using the proposed model to analyze the impact of different applied weights on bit and surface rotary speeds on the system vibrations. This information provides insights into optimization of drilling operation.
Combined Optimal Design and Control of a Near Isothermal Liquid Piston Air Compressor/Expander for a Compressed Air Energy Storage (CAES) System for Wind Turbines
Authors: Saadat Mohsen , Li Perry Y.
Published: January 2016

The key component of Compressed Air Energy Storage (CAES) system is an air compressor/expander. The roundtrip efficiency of this energy storage technology depends greatly on the efficiency of the air compressor/expander. There is a trade off between the thermal efficiency and power density of this component. Different ideas and approaches were introduced and studied in the previous works to improve this trade off by enhancing the heat transfer between air and its environment. In the present work, a combination of optimal compression/expansion rate, optimal chamber shape and optimal heat exchanger material distribution in the chamber is considered to maximize the power density of a compression/expansion chamber for a given desired efficiency. Results show that the power density can be improved by more than 20 folds if the optimal combination of flow rate, shape and porosity are used together.
A Continuous-Field Actuation Method for Transducing Optical Color Images to Magnetic/Eddy-Current Patterns
Authors: Lee Kok-Meng , Lin Chun-Yeon , Li Min
Published: January 2016

Motivated by two applications (retinal prosthesis and nondestructive damage detection), this research develops a new actuator utilizing magnetic/electric fields as media to enable open-loop induction control of a relatively high-resolution eddy-current pattern on an electrically conductive surface with a relatively small number of electromagnets (EMs). The actuator referred to here as a magnetic/eddy-current (M/EC) continuous field scanner transduces an image into an M/EC pattern induced by a two-dimensional EM array. Unlike traditional digital stimulation devices where the spatial resolution is defined by discrete spacing between two adjacent electrodes, the continuous-field scanner accurately controls the synthetized M/EC fields between adjacent EMs. Along with a detailed presentation of an analytical model and its inverse solutions to enable the continuous-field scanning, this paper presents a numerical study to investigate the effects of key design parameters, and some preliminary experimental results to validate the concept feasibility of the proposed method.
Distributed Navigation Strategy of Mobile Sensor Networks With Probabilistic Wireless Communication Links
Authors: Madhag Aqeel , Choi Jongeun
Published: January 2016

Mobile sensor networks have been widely used to predict spatio-temporal physical phenomena for various scientific and engineering applications. To accommodate the realistic models of mobile sensor networks, we incorporated probabilistic wireless communication links based on packet reception ratio (PRR) with distributed navigation. We then derived models of mobile sensor networks that predict Gaussian random fields from noise-corrupted observations under probabilistic wireless communication links. For the given model with probabilistic wireless communication links, we derived the prediction error variances for further sampling locations. Moreover, we designed a distributed navigation that minimizes the network cost function formulated in terms of the derived prediction error variances. Further, we have shown that the solution of distributed navigation with the probabilistic wireless communication links for mobile sensor networks are uniformly ultimately bounded with respect to that of the distributed one with the R-disk communication model. According to Monte Carlo simulation results, agent trajectories under distributed navigation with the probabilistic wireless communication links are similar to those with the R-disk communication model, which confirming the theoretical analysis.
Analysis of a Tele-Operated MRI-Compatible Vane Actuator for Neuromuscular Facilitation in Hemiparetic Limbs
Authors: Turkseven Melih , Kovalenko Ilya , Kim Euisun , Ueda Jun
Published: January 2016

This paper analyzes the suitability of pneumatically driven, MRI-compatible vane actuators for stroke rehabilitation, particularly functional recovery of hemiparetic limbs. Hemiparesis patients suffer a sudden loss of motor skills in the upper-limb due to brain injury, such as stroke. As an emerging physio-therapy technique for hemiparesis, named repetitive facilitation exercise, or RFE, a therapist manually applies brief mechanical stimuli to the peripheral target muscles (e.g., tapping, stretching of tendon/muscle) followed by wrist pronation/supination immediately before a patient intends to produce a movement with the muscle. In an earlier study, a robotic system that replicates the mechanical tendon stimulation part of RFE procedure in MRI with the required timing precision has been developed and tested by the authors to investigate the underlying principles of functional recovery via RFE. This work presents the design of a vane actuator that fits into the tight space in MR-scanners, and analyzes its dynamic performance via a detailed pneumatic system model. The analysis indicates that a pneumatically driven, tele-operated vane actuator can satisfy the dynamic requirements of the targeted rehabilitation procedure.
Effective Brake Torque Allocation in Regenerative Braking System Considering Shaft Vibration Using Model Predictive Control
Authors: Naik Bhushan , Shim Taehyun
Published: January 2016

A regenerative brake system is an effective way of recovering energy that would be lost as heat during brake operation, and such systems are widely used in hybrid and electric vehicles. This paper presents a multi-objective method for allocating brake torque between the hydraulic and regenerative brake systems using model predictive control. The proposed control method has two objectives: bandwidth-based torque allocation and reduction in driveshaft vibrations. A quarter-car model with a PMSM electric drive system is used to investigate this control method’s effectiveness. The simulation results show that the vehicle stopping distance and the drive shaft vibrations will be reduced with the proposed control strategy.
Attenuation correction in emission tomography using the emission data—A review
Authors: Berker Yannick , Li Yusheng
Published: January 2016

The problem of attenuation correction (AC) for quantitative positron emission tomography (PET) had been considered solved to a large extent after the commercial availability of devices combining PET with computed tomography (CT) in 2001; single photon emission computed tomography (SPECT) has seen a similar development. However, stimulated in particular by technical advances toward clinical systems combining PET and magnetic resonance imaging (MRI), research interest in alternative approaches for PET AC has grown substantially in the last years. In this comprehensive literature review, the authors first present theoretical results with relevance to simultaneous reconstruction of attenuation and activity. The authors then look back at the early history of this research area especially in PET; since this history is closely interwoven with that of similar approaches in SPECT, these will also be covered. We then review algorithmic advances in PET, including analytic and iterative algorithms. The analytic approaches are either based on the Helgason–Ludwig data consistency conditions of the Radon transform, or generalizations of John's partial differential equation; with respect to iterative methods, we discuss maximum likelihood reconstruction of attenuation and activity (MLAA), the maximum likelihood attenuation correction factors (MLACF) algorithm, and their offspring. The description of methods is followed by a structured account of applications for simultaneous reconstruction techniques: this discussion covers organ‐specific applications, applications specific to PET/MRI, applications using supplemental transmission information, and motion‐aware applications. After briefly summarizing SPECT applications, we consider recent developments using emission data other than unscattered photons. In summary, developments using time‐of‐flight (TOF) PET emission data for AC have shown promising advances and open a wide range of applications. These techniques may both remedy deficiencies of purely MRI‐based AC approaches in PET/MRI and improve standalone PET imaging.
Parameterization of photon beam dosimetry for a linear accelerator
Authors: Lebron Sharon , Lu Bo , Yan Guanghua , Kahler Darren , Li Jonathan G. , Barraclough Brendan , Liu Chihray
Published: January 2016

Purpose:

In radiation therapy, accurate data acquisition of photon beam dosimetric quantities is important for (1) beam modeling data input into a treatment planning system (TPS), (2) comparing measured and TPS modeled data, (3) the quality assurance process of a linear accelerator's (Linac) beam characteristics, (4) the establishment of a standard data set for comparison with other data, etcetera. Parameterization of the photon beam dosimetry creates a data set that is portable and easy to implement for different applications such as those previously mentioned. The aim of this study is to develop methods to parameterize photon beam dosimetric quantities, including percentage depth doses (PDDs), profiles, and total scatter output factors (Scp).

Methods:

Scp, PDDs, and profiles for different field sizes, depths, and energies were measured for a Linac using a cylindrical 3D water scanning system. All data were smoothed for the analysis and profile data were also centered, symmetrized, and geometrically scaled. The Scp data were analyzed using an exponential function. The inverse square factor was removed from the PDD data before modeling and the data were subsequently analyzed using exponential functions. For profile modeling, one halfside of the profile was divided into three regions described by exponential, sigmoid, and Gaussian equations. All of the analytical functions are field size, energy, depth, and, in the case of profiles, scan direction specific. The model's parameters were determined using the minimal amount of measured data necessary. The model's accuracy was evaluated via the calculation of absolute differences between the measured (processed) and calculated data in low gradient regions and distance‐to‐agreement analysis in high gradient regions. Finally, the results of dosimetric quantities obtained by the fitted models for a different machine were also assessed.

Results:

All of the differences in the PDDs' buildup and the profiles' penumbra regions were less than 2 and 0.5 mm, respectively. The differences in the low gradient regions were 0.20% ± 0.20% (<1% for all) and 0.50% ± 0.35% (<1% for all) for PDDs and profiles, respectively. For Scp data, all of the absolute differences were less than 0.5%.

Conclusions:

This novel analytical model with minimum measurement requirements was proved to accurately calculate PDDs, profiles, and Scp for different field sizes, depths, and energies.
Technical Note: Spot characteristic stability for proton pencil beam scanning a)
Authors: Chen Chin‐Cheng , Chang Chang , Moyers Michael F. , Gao Mingcheng , Mah Dennis
Published: January 2016

Purpose:

The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil beam scanning.

Methods:

A simple treatment plan was generated to produce an asymmetric 9‐spot pattern distributed throughout a field of 16 × 18 cm for each of 18 proton energies (100.0–226.0 MeV). The delivered fluence distribution in air was measured using a phosphor screen based CCD camera at three planes perpendicular to the beam line axis (x‐ray imaging isocenter and up/down stream 15.0 cm). The measured fluence distributions for each energy were analyzed using in‐house programs which calculated the spot sizes and positional deviations of the Gaussian shaped spots.

Results:

Compared to the spot characteristic data installed into the treatment planning system, the 16‐month averaged deviations of the measured spot sizes at the isocenter plane were 2.30% and 1.38% in the IEC gantry x and y directions, respectively. The maximum deviation was 12.87% while the minimum deviation was 0.003%, both at the upstream plane. After the collinearity of the proton and x‐ray imaging system isocenters was optimized, the positional deviations of the spots were all within 1.5 mm for all three planes. During the site configuration update, spot positions were found to deviate by 6 mm until the tuning parameters file was properly restored.

Conclusions:

For this beam delivery system, it is recommended to perform a spot size and position check at least monthly and any time after a database update or cyclotron intervention occurs. A spot size deviation tolerance of <15% can be easily met with this delivery system. Deviations of spot positions were <2 mm at any plane up/down stream 15 cm from the isocenter.
Adapting Koch's postulates
Authors: Byrd Allyson L. , Segre Julia A.
Published: January 2016

Criteria for disease causation must take microbial interactions into account
Draft Genome Sequence of Streptococcus orisasini SH06, Isolated from a Healthy Thoroughbred Gastrointestinal Tract
Authors: Takagi Misako , Nakano Akiyo , Toh Hidehiro , Oshima Kenshiro , Arakawa Kensuke , Nakajima Fumihiko , Tashiro Kosuke , Kikusui Tekefumi , Yanagida Fujitoshi , Morita Hidetoshi
Published: January 2016

Streptococcus orisasiniSH06 was isolated from a healthy thoroughbred gastrointestinal tract. Here, we report the draft genome sequence of this organism. This paper is the first published report of the genomic sequence ofS. orisasini.
Draft Genome Sequence of “
Cohnella kolymensis
” B-2846
Authors: Karlyshev Andrey V. , Kudryashova Ekaterina B. , Ariskina Elena V.
Published: January 2016

A draft genome sequence of “
Cohnella kolymensis
” strain B-2846 was derived using IonTorrent sequencing technology. The size of the assembly and G+C content were in agreement with those of other species of this genus. Characterization of the genome of a novel species of
Cohnella
will assist in bacterial systematics.
Nascent Genomic Evolution and Allopatric Speciation of Myroides profundi D25 in Its Transition from Land to Ocean
Authors: Zhang Yu-Zhong , Li Yi , Xie Bin-Bin , Chen Xiu-Lan , Yao Qiong-Qiong , Zhang Xi-Ying , Kempher Megan L. , Zhou Jizhong , Oren Aharon , Qin Qi-Long
Published: January 2016

A large amount of bacterial biomass is transferred from land to ocean annually. Most transferred bacteria should not survive, but undoubtedly some do. It is unclear what mechanisms these bacteria use in order to survive and even thrive in a new marine environment.
Myroides profundi
D25
T
, a member of the
Bacteroidetes
phylum, was isolated from deep-sea sediment of the southern Okinawa Trough near the China mainland and had high genomic sequence identity to and synteny with the human opportunistic pathogen
Myroides odoratimimus
. Phylogenetic and physiological analyses suggested that
M. profundi
recently transitioned from land to the ocean. This provided an opportunity to explore how a bacterial genome evolved to survive in a novel environment. Changes in the transcriptome were evaluated when both species were cultured under low-salinity conditions and then transferred to high-salinity conditions. Comparative genomic and transcriptomic analyses showed that
M. profundi
altered transcription regulation in the early stages of survival. In these stages, vertically inherited genes played a key role in the survival of
M. profundi
. The contribution of
M. profundi
unique genes, some possibly acquired by horizontal gene transfer (HGT), appeared relatively small, and expression levels of unique genes were diminished under the high-salinity conditions. We postulate that HGT genes might play an important role in longer-term adaptation. These results suggested that some human pathogens might have the ability to survive in and adapt to the marine environment, which may have important implications for public health control in coastal regions.

IMPORTANCE
Horizontal gene transfer (HGT) is considered to be important for bacteria to adapt to a different microhabitat. However, our results showed that vertically inherited genes might play more important roles than HGT genes in the nascent adaptation to the marine environment in the bacterium
Myroides profundi
, which has recently been transferred from land to ocean.
M. profundi
unique genes had low expression levels and were less regulated under high-salinity conditions, indicating that the contribution of HGT genes to survival of this bacterium under marine high-salinity conditions was limited. In the early adaptation stages,
M. profundi
apparently survived and adapted mainly by regulating the expression of inherited core genes. These results may explain in part why human pathogens can easily be detected in marine environments.
Newspaper coverage of maternal health in Bangladesh, Rwanda and South Africa: a quantitative and qualitative content analysis
Authors: Gugsa Frey , Karmarkar Ellora , Cheyne Andrew , Yamey Gavin
Published: January 2016

Objective

To examine newspaper coverage of maternal health in three countries that have made varying progress towards Millennium Development Goal 5 (MDG 5): Bangladesh (on track), Rwanda (making progress, but not on track) and South Africa (no progress).

Design

We analysed each country's leading national English-language newspaper: Bangladesh'sThe Daily Star, Rwanda'sThe New Times/The Sunday Times, and South Africa'sSunday Times/The Times. We quantified the number of maternal health articles published from 1 January 2008 to 31 March 2013. We conducted a content analysis of subset of 190 articles published from 1 October 2010 to 31 March 2013.

Results

Bangladesh'sThe Daily Starpublished 579 articles related to maternal health from 1 January 2008 to 31 March 2013, compared to 342 in Rwanda'sThe New Times/The Sunday Timesand 253 in South Africa'sSunday Times/The Timesover the same time period.The Daily Starhad the highest proportion of stories advocating for or raising awareness of maternal health. Most maternal health articles inThe Daily Star(83%) andThe New Times/The Sunday Times(69%) used a ‘human-rights’ or ‘policy-based’ frame compared to 41% of articles fromSunday Times/The Times.

Conclusions

In the three countries included in this study, which are on different trajectories towards MDG 5, there were differences in the frequency, tone and content of their newspaper coverage of maternal health. However, no causal conclusions can be drawn about this association between progress on MDG 5 and the amount and type of media coverage of maternal health.
Protocol for a prospective, longitudinal, cohort study of postconcussive symptoms in children: the Take C.A.Re (Concussion Assessment and Recovery Research) study
Authors: Bressan Silvia , Takagi Michael , Anderson Vicki , Davis Gavin A , Oakley Ed , Dunne Kevin , Clarke Cathriona , Doyle Melissa , Hearps Stephen , Ignjatovic Vera , Seal Marc , Babl Franz E
Published: January 2016

Introduction

A substantial minority of children who sustain a concussion suffer prolonged postconcussive symptoms. These symptoms can persist for more than 1 month postinjury and include physical, cognitive, behavioural and emotional changes. Those affected can develop significant disability, diminishing their quality of life. The precise prevalence of postconcussive symptoms following child concussion is unclear, with heterogeneous and at times conflicting results published regarding factors that predict children at risk for developing long-lasting postconcussive symptoms. The aim of the Take C.A.Re (Concussion Assessment and Recovery Research) study is to provide an in-depth multidimensional description of the postconcussive recovery trajectories from a physical, neurocognitive and psychosocial perspective in the 3 months following concussion, with a focus on the early postconcussive period, and identification of factors associated with prolonged recovery.

Methods and analysis

Take C.A.Re is a prospective, longitudinal study at a tertiary children's hospital, recruiting and assessing patients aged 5–<18 years who present to the emergency department with a concussion and following them at 1–4 days, 2 weeks, 1 month and 3 months postinjury. Multiple domains are assessed: postconcussive symptoms, balance and coordination, neurocognition, behaviour, quality of life, fatigue, post-traumatic stress symptoms, parental distress and family burden. ‘Delayed recovery’ is operationalised as the presence of ≥3 symptoms on the Post Concussive Symptoms Inventory rated as worse compared with baseline. Main analyses comprise analysis of variance (recovery trajectories, delayed vs normal recovery groups) and regression analyses of predictors of recovery (preinjury, acute and family factors).

Ethics and dissemination

Ethical approval has been obtained through the Royal Children's Hospital Melbourne Human Research Ethics Committee (33122). We aim to disseminate the findings through international conferences, international peer-reviewed journals and social media.

Trial registration number

ACTRN12615000316505.
Towards a ‘patient-centred’ operationalisation of the new dynamic concept of health: a mixed methods study
Authors: Huber M , van Vliet M , Giezenberg M , Winkens B , Heerkens Y , Dagnelie P C , Knottnerus J A
Published: January 2016

Objective

To evaluate among stakeholders the support for the new, dynamic concept of health, as published in 2011: ‘Health as the ability to adapt and to self-manage’, and to elaborate perceived indicators of health in order to make the concept measurable.

Design

A mixed methods study: a qualitative first step with interviews and focus groups, followed by a quantitative survey.

Participants

Representatives of seven healthcare stakeholder domains, for example, healthcare providers, patients with a chronic condition and policymakers. The qualitative study involved 140 stakeholders; the survey 1938 participants.

Results

The new concept was appreciated, as it addresses people as more than their illness and focuses on strengths rather than weaknesses. Caution is needed as the concept requires substantial personal input of which not everyone is capable. The qualitative study identified 556 health indicators, categorised into six dimensions:bodily functions, mental functions and perception, spiritual/existential dimension, quality of life, social and societal participation,anddaily functioning,with 32 underlying aspects. The quantitative study showed all stakeholder groups consideringbodily functionsto represent health, whereas for other dimensions there were significant differences between groups. Patients considered all six dimensions almost equally important, thus preferring a broad concept of health, whereas physicians assessed health more narrowly and biomedically. In the qualitative study, 78% of respondents considered their health indicators to represent the concept.

Conclusions

To prevent confusion with health as ‘absence of disease’, we propose the use of the term ‘positive health’ for the broad perception of health with six dimensions, as preferred by patients. This broad perception deserves attention by healthcare providers as it may support shared decision-making in medical practice. For policymakers, the broad perception of ‘positive health’ is valuable as it bridges the gap between healthcare and the social domain, and by that it may demedicalise societal problems.