bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Control of Surface Quality in Chemical Mechanical Planarization (CMP)
Authors: Poosarla Pavan , Emadi Hamid , Chandra Abhijit , Bhattacharya Sourabh
Published: November 2017

Obtaining uniform surface finish across large length scales is extremely important in Chemical Mechanical Planarization (CMP). Existing control strategies use results from model simulations to propose open-loop control strategies to reduce the step height on surfaces being polished. In the present work, we propose a strategy to control the surface profile of substrate during CMP process. The evolution of the surface profile is predicted using the state space model of the polishing process. The resulting state space equation is solved and a closed form solution of the surface profile is obtained as a function of time. Based on the solution, we provide a fundamental limitation for the machining process in terms of the extent of planarization that can be achieved for a given material budget.
Investigation of Nanoscale Poroelasticity of Eukaryotic Cells Using Atomic Force Microscopy
Authors: Mollaeian Keyvan , Liu Yi , Ren Juan
Published: November 2017

Intracellular network deformation of the cell plays an important role in cellular shape formation. Recent studies suggest that cell reshaping and deformation due to external forces involves cellular volume, pore size, elasticity, and intracellular filaments polymerization rate changes. This behavior of live cells can be described by poroelastic models because of the porous structure of the cytoplasm. In this study, the poroelasticity of human mammary basel/claudin low carcinoma cell (MDA-MB-231) was investigated using indentation-based atomic force microscopy. The effects of cell deformation (i.e., indentation) rate on the poroelasticity of MDA-MB-231 cells were studied. Specifically, the cell poroelastic behavior (i.e., the diffusion coefficient) was quantified at different indenting velocities (0.2, 2, 10, 20, 100, 200 μm/s) by fitting the force-relaxation curves using a poroelastic model. It was found that the in general the MDA-MB-231 cells behaved poroelastic, and they were less poroelastic (i.e., with lower diffusion coefficient) at higher indenting velocities due to the local stiffening up caused by faster force loads. Poor poroelastic relaxation was observed when the indenting velocity was lower than 10 μm/s due to the intracelluar fluid redistribution during the slow indenting process to equilibrate the intracellular pressure. Moreover, the measurement results showed that the pore size reduction caused by local stiffening at faster indenting velocities is more dominant than the Young’s modulus in affecting the cell poroelasticity.
Induction Motor Fault Diagnosis and Classification Through Sparse Representation
Authors: Zhang Jianjing , Wang Peng , Sun Chuang , Yan Ruqiang , Gao Robert X.
Published: November 2017

Condition monitoring and fault diagnosis of induction motor play a critical role in operation safety and production efficiency. In recent study, sparse representation has demonstrated its simplicity in training, robustness to noise and high accuracy in classification. This paper evaluates the effectiveness of sparse representation as an alternative approach to induction motor fault diagnosis with fault classification rate and robustness to noise as performance measure. Aiming at eliminating the human intervention in fault characteristic frequency detection and extensive feature extraction steps in traditional method, the spatial pattern of the vibration signal is studied as the classifier input. The residual sparsity index (RSI) is proposed to quantify the degree of multi-class data separation and evaluate the reliability of classification results. Experimental results show that the sparse representation method using vibration signal achieves high motor multi-fault classification accuracy and good robustness to noise, with no human intervention required for fault characteristic pattern detection and the need for long feature extraction eliminated. Finally, RSI confirms the high overall reliability of classification results.
State Estimation for Lithium Ion Batteries With Phase Transition Materials
Authors: Koga Shumon , Camacho-Solorio Leobardo , Krstic Miroslav
Published: November 2017

Lithium Iron Phosphate (LiFePO4 or LFP) is a common active material in lithium-ion batteries. It has been observed that this material undergoes phase transitions during the normal charge and discharge operation of the battery. Electrochemical models of lithium-ion batteries can be modified to account for this phenomena at the expense of some added complexity. We explore this problem for the single particle model (SPM) where the underlying dynamic model for diffusion of lithium ions in phase transition materials is a partial differential equation (PDE) with a moving boundary. An observer is derived for the concentration of lithium ions from the SPM via the backstepping method for PDEs in a rigorous way and simulations are provided to illustrate the performance of the observer. Our comments are stated on the gap between the proposed observer and a complete state-of-charge (SoC) estimation algorithm for lithium-ion batteries with phase transition materials.
Five State Analytical Model of Proton Exchange Membrane Fuel Cell
Authors: Milanovic Milos , Rose Patrick , Radisavljevic-Gajic Verica , Clayton Garrett
Published: November 2017

In this paper a full nonlinear dynamic control oriented mathematical model of Proton Exchange Membrane (PEM) fuel cell system is developed. The model is structured as a nonlinear five state space model. The derivation of each state equation is based on physics fundamental principles using thermodynamic theory of ideal gas mixtures, conservation of mass law, flow dynamics in serpentine flow channels and diffusion. The output of proposed model, stack voltage, is developed from Nernst equation that includes three main types of losses occurring in the fuel cell. The unknown parameters of the model are estimated and fitted using sets of steady state experimental data. Stack polarization curve of the proposed model is validated by using sets of data for three different values of inlet pressures. Experimental setup used to attain data is the Greenlight Innovation G60 fuel cell test station system and TP50 Fuel Cell stack.
Admittance Based Force Control for Collaborative Transportation of a Common Payload Using Two UAVs
Authors: Barawkar Shraddha , Radmanesh Mohammadreza , Kumar Manish , Cohen Kelly
Published: November 2017

This paper presents a novel control approach to perform collaborative transportation by using multiple quadcopter Unmanned Aerial Vehicles (UAVs). In this paper, a leader-follower approach is implemented. The leader UAV uses a Proportional, Integral and Derivative (PID) controller to reach the desired goal point or follow a predefined trajectory. Traditionally, a Position Feedback Controller (PFC) has been used in literature to control the follower UAV. PFC takes the feedback of leader UAVs position to control the follower UAV. Such control schemes work effectively in indoor environments using accurate motion tracking cameras. However, the paper focuses on outdoor applications that requires usage of Global Positioning System (GPS) to receive the positional information of the leader UAV. GPS has inherent errors of order of magnitude that can destabilize the system. The control scheme proposed in this research addresses this major limitation. In this paper, a Force Feedback Controller (FFC) is used to control the follower UAV. An admittance controller is employed to implement this FFC. This controller simulates a virtual spring mass damper system, to generate a desired trajectory for the follower UAV, which complies with the contact forces acting on it. This desired trajectory is then tracked by a traditional PID controller. With the proposed control scheme, the follower UAV can be controlled without using leaders positional feedback and the system can be implemented for real-world applications. The paper presents results of numerical simulations showing the effectiveness of the proposed controller for way-point navigation and complex trajectory tracking.
Robust Weight-on-Bit Tracking in Drilling Operations: A Stochastic, Nonlinear Approach
Authors: Pournazari Parham , Fernández Benito R. , van Oort Eric
Published: November 2017

Accurate control of weight-on-bit (WOB) in oil and gas drilling plays an important role in achieving high rates of penetration (ROP) and minimizing drillstring vibrations. In this paper, we propose a nonlinear, stochastic model of downhole WOB, and provide a framework for estimation, and control of the proposed model. We focus on real-time estimation of modeling and measurement uncertainties, and use these estimates to adapt the controller characteristics accordingly. The presented methodology is simulated for various scenarios, and benchmarked against existing control techniques in the industry.
Mutual Information Control for Target Acquisition: A Method to Localize a Gas/Chemical Plume Source Using a Mobile Sensor
Authors: Bourne Joseph R. , Leang Kam K.
Published: November 2017

This paper presents a motion control algorithm that exploits mutual information and a Bayesian filter to optimally guide a mobile robotic sensor, e.g., an unmanned aerial or ground vehicle (UAV or UGV) with a sensor, to localize an unknown target such as the source of a gas/chemical leak. Specifically, optimal feedforward inputs are found such that with respect to the posterior distribution, the robot moves to minimize uncertainty. The formulation depends on the robot’s dynamics model and the sensor’s stochastic measurement model. Additionally, a utility function is defined such that the estimator’s uncertainty is minimized, i.e., the acquisition of information is maximized. The approach is applied to a single robot with three different sensor models for validation. In particular, for the chemical concentration sensor case a Gaussian plume likelihood model is assumed and simulation results show that a single robot can effectively localize the unknown source, demonstrating the effectiveness of the approach.
Modeling and Energy Cost Optimization of Air Conditioning Loads in Smart Grid Environments
Authors: Chan Korey , Bashash Saeid
Published: November 2017

Electricity for heating, ventilation, and air condition (HVAC) machines takes up a large percentage of energy consumption in the buildings and thus in turn, a large portion of the energy monetary cost. Optimization of air conditioners use throughout the day will reduce energy consumption and expenditure. This study introduces a second-order differential equation model to capture the indoor temperature dynamics of a building. An experimental test bed is developed to collect a set of indoor/outdoor temperature and sunlight data. Using a least-squares-based system identification process, the model parameters are identified and checked through simulation. Optimization of the room temperature is then determined by solving a mixed-integer quadratic programming problem in relation to the hourly-updated energy prices. Mixed-integer quadratic programming solution is compared to a two-point thermostatic control system. A hybrid solution compromising the quadratic programming algorithm and the conventional thermostatic control scheme is proposed as a tractable approach for the near-optimal energy management of the system.
How to Beat Flappy Bird: A Mixed-Integer Model Predictive Control Approach
Authors: Piper Matthew , Bhounsule Pranav , Castillo-Villar Krystel K.
Published: November 2017

Flappy Bird is a mobile game that involves tapping the screen to navigate a bird through a gap between pairs of vertical pipes. When the bird passes through the gap, the score increments by one and the game ends when the bird hits the floor or a pipe. Surprisingly, Flappy Bird is a very difficult game and scores in single digits are not uncommon even after extensive practice. In this paper, we create three controllers to play the game autonomously. The controllers are: (1) a manually tuned controller that flaps the bird based on a vertical set point condition; (2) an optimization-based controller that plans and executes an optimal path between consecutive tubes; (3) a model-based predictive controller (MPC). Our results showed that on average, the optimization-based controller scored highest, followed closely by the MPC, while the manually tuned controller scored the least. A key insight was that choosing a planning horizon slightly beyond consecutive tubes was critical for achieving high scores. The average computation time per iteration for the MPC was half that of optimization-based controller but the worst case time (maximum time) per iteration for the MPC was thrice that of optimization-based controller. The success of the optimization-based controller was due to the intuitive tuning of the terminal position and velocity constraints while for the MPC the important parameters were the prediction and control horizon. The MPC was straightforward to tune compared to the other two controllers. Our conclusion is that MPC provides the best compromise between performance and computation speed without requiring elaborate tuning.
Towards Understanding Human Decisions in Human-Robot Interactions
Authors: Zhang Wenlong , Yang Yezhou , Ren Yi
Published: November 2017

In this paper, we conducted an experiment with four human participants whom were asked to follow a robot gripper with unknown motion as close as possible. The results show that human beings resort to a fairly complicated and continuously changing control strategy. We hypothesize that this strategy can be explained by (1) a feedforward (preview) model of the machine’s motion, and further by (2) human being’s uncertainty in this preview. To test (1), we demonstrate that feedforward control can indeed improve the fitting of the model to the experimental data, and that the feedback gain and the preview length vary across subjects. This model, however, does not explain temporally changing human behavior observed during the experiment. To this end, we propose an extension of the human control model where human behavior is influenced by the preview uncertainty. The extended model incorporates a higher-level planner that determines a target state for a short time interval, and a lower-level controller that meets the target through real-time control. The developed model helps predict detailed human behavior during their interactions with robots.
Comparing the Effects of Intrinsic and Extrinsic Noise on the Vicsek Model in Three Dimensions
Authors: Shirazi Masoud Jahromi , Abaid Nicole
Published: November 2017

A group of simple individuals may show ordered, complex behavior through local interactions. This phenomenon is called collective behavior, which has been observed in a vast variety of natural systems such as fish schools or bird flocks. The Vicsek model is a well-established mathematical model to study collective behavior through interaction of individuals with their neighbors in the presence of noise. How noise is modeled can impact the collective behavior of the group. Extrinsic noise captures uncertainty imposed on individuals, such as noise in measurements, while intrinsic noise models uncertainty inherent to individuals, akin to free will. In this paper, the effects of intrinsic and extrinsic noise on characteristics of the transition between order and disorder in the Vicsek model in three dimensions are studied through numerical simulation.
Under-Actuated Humanoid Model With Elastomeric Springs
Authors: Fry Christian , Coram Stanley , Piovesan Davide
Published: November 2017

This paper presents the mechanical modifications and simulation of a bipedal humanoid system actuated with linear springs to produce a standing equilibrium position.

The original humanoid system is comprised of two leg assemblies connected by a hip bracket. Eleven pairs of springs were attached to the system in locations designed to simulate the muscles and tendons in a human body.

The next evolution of the LUIGEE project is the inclusion of three servo motors per leg and a series of elastomeric springs. Although servo motors have been introduced, it is desired to maintain the passive, static aspect of the previous prototype. This paper reports on part modifications to accommodate servo motors and the introduction of polymeric springs that guarantee static stability. ABS plastic and photopolymer resin was used to produce the new model. Due to the size of the motors, some parts of the original robot were redesigned. The new design iteration was stimulated using SimWise 4D®, where the hysteretic effect of rubber was modelled with an equivalent viscous damping.
Filtering Characteristics of String Hydraulic Pulsation Attenuator
Authors: Shang Xia , Zhou Hua , Xie Anhuan , Zhu Jiabin
Published: November 2017

In order to attenuate the pulsation of the hydraulic systems, the string hydraulic pulsation attenuator is proposed using the principle of mechanical vibration absorption. We present a new type of mechanical structure that can attenuate the pulsation as well as reduce the noise. Elastic strings and fluid can be seen as a forced vibratory system. Resonant cavities isolated by inner pipes of the string hydraulic pulsation attenuator and the damping orifices on inner pipes constitute the Helmholtz resonant structure. It’s a way to realize the effect of structural resonant and fluid resonant filtering. Based on the dynamic characteristics of the pipeline, the transfer matrix model of the string hydraulic pulsation attenuator is established. The attenuation performance of the string hydraulic pulsation attenuator is evaluated by insertion loss. In MATLAB software, we simulate the pulsating characteristics to analyze the relationship between the main structural parameters and the characteristics of pulsating pressure. The simulated theoretical results are compared and analyzed, which indicates that the string hydraulic pulsation attenuator is very effective for filtering in a very wide frequency range. Pulsation attenuating is good for improving the life of components and the working reliability. Noise reducing is good for people’s health at the working-site. Especially under some secret circumstances, controlling noise is a must.
A Stochastic Approach to the Convex Optimization of Non-Convex Discrete Energy Systems
Authors: Burger Eric M. , Moura Scott J.
Published: November 2017

Energy systems (e.g. ventilation fans, refrigerators, and electrical vehicle chargers) often have binary or discrete states due to hardware limitations and efficiency characteristics. Typically, such systems have additional programmatic constraints, such as minimum dwell times to prevent short cycling. As a result, non-convex techniques, like dynamic programming, are generally required for optimization. Recognizing developments in the field of distributed convex optimization and the potential for energy systems to participate in ancillary power system services, it is advantageous to develop convex techniques for the approximate optimization of energy systems. In this manuscript, we develop the alternative control trajectory representation — a novel approach for representing the control of a non-convex discrete system as a convex program. The resulting convex program provides a solution that can be interpreted stochastically for implementation.
Applications and Optimization of a Constant Flux Magnetostrictive Impact Sensor
Authors: Weld Kevin , Uras Mehmet , Ulsoy A. Galip
Published: November 2017

Applications of a constant flux magnetostrictive impact sensor as an engine mount energy harvester and side impact sensor are presented and their operation is discussed. An optimization method is developed and appropriate objective functions are created for each application. Optimization results are presented including a power output increase of the engine mount energy harvester of 65% and a decrease in response time of the side impact sensor to impact events while also decreasing sensor output to non-impact events.
Maximum Correntropy Criterion Constrained Kalman Filter
Authors: Fakoorian Seyed , Moosavi Mahmoud , Izanloo Reza , Azimi Vahid , Simon Dan
Published: November 2017

Non-Gaussian noise may degrade the performance of the Kalman filter because the Kalman filter uses only second-order statistical information, so it is not optimal in non-Gaussian noise environments. Also, many systems include equality or inequality state constraints that are not directly included in the system model, and thus are not incorporated in the Kalman filter. To address these combined issues, we propose a robust Kalman-type filter in the presence of non-Gaussian noise that uses information from state constraints. The proposed filter, called the maximum correntropy criterion constrained Kalman filter (MCC-CKF), uses a correntropy metric to quantify not only second-order information but also higher-order moments of the non-Gaussian process and measurement noise, and also enforces constraints on the state estimates. We analytically prove that our newly derived MCC-CKF is an unbiased estimator and has a smaller error covariance than the standard Kalman filter under certain conditions. Simulation results show the superiority of the MCC-CKF compared with other estimators when the system measurement is disturbed by non-Gaussian noise and when the states are constrained.
An Adaptive PID Controller Based on Bayesian Theory
Authors: Gadsden S. Andrew
Published: November 2017

One of the most popular trajectory-tracking controllers used in industry is the PID controller. The PID controller utilizes three types of gains and the tracking error in order to provide a control gain to a system. The PID gains may be tuned manually or using a number of different techniques. Under most operating conditions, only one set of PID gains are used. However, techniques exist to compensate for dynamic systems such as gain scheduling or basic time-varying functions. In this paper, an adaptive PID controller is presented based on Bayesian theory. The interacting multiple model (IMM) method, which utilizes Bayes’ theorem and likelihood functions, is implemented on the PID controller to present an adaptive control strategy. The strategy is applied to a simulated electromechanical system, and the results of the proposed controller are compared with the standard PID method. Future work is also considered.
Model Predictive Control of a Lean-Burn Gasoline Engine Coupled With a Passive Selective Catalytic Reduction System
Authors: Lin Qinghua , Chen Pingen , Prikhodko Vitaly Y.
Published: November 2017

Lean-burn gasoline engines have demonstrated 10–20% engine efficiency gain over stoichiometric engines and are widely considered as a promising technology for meeting the 54.5 miles-per-gallon (mpg) Corporate Average Fuel Economy standard by 2025. Nevertheless, NOx emissions control for lean-burn gasoline for meeting the stringent EPA Tier 3 emission standards has been one of the main challenges towards the commercialization of highly-efficient lean-burn gasoline engines in the United States. Passive selective catalytic reduction (SCR) systems, which consist of a three-way catalyst and SCR, have demonstrated great potentials of effectively reducing NOx emissions for lean gasoline engines but may cause significant fuel penalty due to ammonia generation via rich engine combustion. The purpose of this study is to develop a model-predictive control (MPC) scheme for a lean-burn gasoline engine coupled with a passive SCR system to minimize the fuel penalty associated with passive SCR operation while satisfying stringent NOx and NH3 emissions requirements. Simulation results demonstrate that the MPC-based control can reduce the fuel penalty by 47.7% in a simulated US06 cycle and 32.0% in a simulated UDDS cycle, compared to the baseline control, while achieving over 96% deNOx efficiency and less than 15 ppm tailpipe ammonia slip. The proposed MPC control can potentially enable high engine efficiency gain for highly-efficient lean-burn gasoline engine while meeting the stringent EPA Tier 3 emission standards.
Locomotion of a Multi-Link Nonholonomic Snake Robot
Authors: Dear Tony , Kelly Scott David , Travers Matthew , Choset Howie
Published: November 2017

Robot system models often have difficulty allowing for direct command over all input degrees of freedom if the system has a large number of imposed constraints. A snake robot with more than three links and a nonholonomic wheel on each link cannot achieve arbitrary configurations in all of its joints simultaneously. For such a system, we assume partial command over a subset of the joints, and allow the rest to evolve according to kinematic chained and dynamic models. Different combinations of commanded and passive joints, as well as the presence of dynamic elements such as torsional springs, can drastically change the coupling interactions and stable oscillations of the joints. We use the oscillation modes that emerge to inform feedback controllers that achieve desired overall locomotion of the robot.
Kalman Filtering-Aided Optical Localization of Mobile Robots: System Design and Experimental Validation
Authors: Greenberg Jason N. , Tan Xiaobo
Published: November 2017

Localization of mobile robots in GPS-denied envrionments (e.g., underwater) is of great importance to achieving navigation and other missions for these robots. In our prior work a concept of Simultaneous Localization And Communication (SLAC) was proposed, where the line of sight (LOS) requirement in LED-based communication is exploited to extract the relative bearing of the two communicating parties for localization purposes. The concept further involves the use of Kalman filtering for prediction of the mobile robot’s position, to reduce the overhead in establishing LOS. In this work the design of such a SLAC system is presented and experimentally evaluated in a two-dimensional setting, where a mobile robot localizes itself through wireless LED links with two stationary base nodes. Experimental results are presented to demonstrate the feasibility of the proposed approach and the important role the Kalman filter plays in reducing the localization error. The effect of the distance between the base nodes on the localization performance is further studied, which bears implications in future SLAC systems where mobile base nodes can be reconfigured adaptively to maximize the localization performance.
Car-Like Ground Vehicle Trajectory Tracking by Using Trajectory Linearization Control
Authors: Chen Yuanyan , Zhu J. Jim
Published: November 2017

This paper focuses on trajectory tracking control for an under-actuated car-like ground vehicle. We consider the 3 degree-of-freedom nonlinear vehicle rigid-body dynamics with nonlinear tire traction force, nonlinear drag forces and actuator dynamics. The control structure employs multi-loop Trajectory Linearization Control (TLC) based on singular perturbation (time-scale separation) theory for exponential stability. The designed controller controls the longitudinal velocity and steering angle simultaneously to follow a feasible guidance trajectory. The paper presents the modeling and design approach with computer simulation results on a scaled-down model car.
Using a Redundant Planar Hip Exoskeleton to Reduce Human-Device Interface Forces
Authors: Schmitthenner David , Shoemaker Samuel H. , Martin Anne E.
Published: November 2017

Robotic exoskeletons have the potential to improve gait rehabilitation. Currently, most exoskeletons use revolute joints that must be exactly aligned with the user’s joints to prevent uncomfortable shear forces at the human-device interface. This paper presents an alternative design for a planar hip exoskeleton based on a planar Stewart platform. In theory, this mechanism does not require exact knowledge of the human hip joint center of rotation to prevent large shear forces. The total human-device system has four degrees of freedom if the human soft tissue is neglected, which does complicate the control of the system compared to a rotational exoskeleton. To find a mapping between the desired human hip angle and the four actuated joints, the task priority method is used. To determine how well the proposed device can guide the hip through a step, dynamic simulations were conducted and compared to the results for a rotational exoskeleton. The compliance in the human soft tissue was included in the simulations because it can play a significant role in both the motion of the system and the human-device forces. Both the ideal case of exact hip joint alignment and the more likely case of hip joint misalignment were considered. In addition, the effects of differing levels of human effort were compared. In all cases, both exoskeletons were well able to guide the human hip in the desired motion. In addition, the novel exoskeleton has significantly lower shear forces at the thigh human-device connection point.
Developing a Novel Robotic Fish With Antagonistic Artificial Muscle Actuators
Authors: Rajendran Sunil Kumar , Zhang Feitian
Published: November 2017

Super-coiled polymer (SCP), one of the newly-developed artificial muscles, has various advantages over traditional artificial muscles in terms of cost, flexibility and power-to-weight ratio. This paper investigates the performance of super-coiled polymer-based actuation in underwater robotics, and presents a novel design of robotic fish using antagonistic SCP actuators. Dynamic model of the robot is derived. An example robotic fish prototype is developed and used in experiments to study SCP actuation for underwater robots. Furthermore, experimental results show that using SCP actuators in robotic fish solves the challenging heat-dissipation problem at ease, thus improving the dynamic response of SCP actuation significantly. A PID controller is designed to regulate the tail flap angle of the designed robotic fish. Simulation results of the closed-loop system are presented to validate the proposed robot design and actuation approach.
Three-Dimensional Analysis of Shape-Morphing Cantilever Oscillations in Viscous Fluids
Authors: Ahsan Syed N. , Aureli Matteo
Published: November 2017

In this paper, we study the linear flexural oscillations of a cantilever beam undergoing chord-wise shape-morphing deformation in a quiescent, Newtonian, viscous fluid. The shape-morphing deformation is prescribed for the beam cross section to an arc of a circle by specifying a periodic maximum curvature continuously along the axis of the structure. This particular strategy is investigated as a possible way to manipulate fluid-structure interaction mechanisms by modifying the hydrodynamic interactions in the vicinity of the submerged structure. Since we focus on the linear vibration of the beam, the fluid flow is described using three-dimensional unsteady Stokes hydrodynamics. By solving the linear unsteady Stokes problem in the frequency domain with a Stokeslet method, we identify the effect of the proposed shape-morphing strategy on the propulsion performance by estimating thrust, lift, and hydrodynamic power dissipation for a range of prescribed deformations. We verify the results obtained from our boundary element method against results from the existing literature. Our findings show a possible improvement in propulsion characteristics and minimization of hydrodynamic power dissipation, for an optimum level of shape-morphing deformation which is aspect ratio-dependent. Results from this study can aid in designing and operating cantilever-based underwater actuation systems for which the multi-objective goal of power losses reduction and propulsion performance improvement is sought.
An Integrated Unmanned Aerial Vehicle System for Vision Based Control
Authors: Zhang Haijie , Zhao Jianguo
Published: November 2017

As the development of computer vision and the popularity of unmanned aerial vehicle, using visual information to control the UAV motion becomes a hotspot. Time-to-contact is one of the concepts that is used to control robot motion such as braking, landing, perching, and obstacle avoidance based on visual information. In this paper, to explore the capability and potential of a direct featureless time-to-contact estimation algorithm for unmanned aerial vehicle motion control, we design an integrated unmanned aerial vehicle system and verify the accuracy of the featureless time-to-contact estimation algorithm. In addition, compressed sensing is combined with the featureless method in time-to-contact estimation to potentially improve the computational speed. The experiment results show that the featureless time-to-contact estimation algorithm, the developed UAV platform and compressed sensing can be readily applied for UAV vision based control.
Motor Resolver Fault Propagation Analysis for Electrified Powertrain
Authors: Li Tianpei , Ahmed Qadeer , Rizzoni Giorgio , Meyer Jason , Boesch Mathew , Badreddine Bader
Published: November 2017

As an integral part of electrified powertrain, resolver is broadly used to do position and speed sensing for electric motors, subject to different types of resolver faults. This paper investigates the resolver fault propagation in electrified powertrain, with focus on the amplitude imbalance, quadrature imperfection and reference phase shift in the resolver position sensing system. The resolver fault effects in the Permanent Magnet Synchronous Machine (PMSM) drive system are first analyzed based on the mathematical model of a surface mounted PMSM with direct Field-oriented Control (FOC). Then the resolver fault propagation in the powertrain is studied in terms of two different motor operating conditions, motor torque control and motor speed control. Simulation is done in Matlab/Simulink based on the PMSM drive model and the powertrain-level simulator to verify the fault propagation analyses. The results can be used to help design the resolver fault diagnostic strategy and determine speed matching condition between engine and electric motor for mode transition control in hybrid electric vehicles.
Dicarboxylic acids analyzed by time-of-flight secondary ions mass spectrometry. Part II: Butanedioic acid
Authors: Trindade Gustavo F. , Ferreira Jose M. , Abel Marie-Laure , Baker Mark A. , Watts John F.
Published: November 2017

Time-of-flight secondary ion mass spectrometry was carried out to analyze a commercially available butanedioic acid (succinic acid) powder. Positive and negative polarity ion spectra were obtained using a 25 keV Bi3+ ion beam rastered over areas of 50 × 50 μm2. The main observed fragments were the protonated molecule [M+H]+ at 119 u and the deprotonated molecule [M-H]− at 117 u with their respective oligomers.
Isolation of isoform-specific binding proteins (Affimers) by phage display using negative selection
Authors: Tang Anna Ah-San , Tiede Christian , Hughes David J. , McPherson Michael J. , Tomlinson Darren C.
Published: November 2017

A Protocol describes how to isolate artificial binding proteins (Affimers) that differentiate between closely related targets.
Papers of note in
Science Translational Medicine
9
(415)
Authors: Ferrarelli Leslie K.
Published: November 2017

This week’s articles describe a way to combat the negative effects of stress on cancer therapy; a potential target in heart failure; and why nighttime wounds heal more slowly than daytime wounds.
Fat expansion through norepinephrine catabolism
Authors: Wong Wei
Published: November 2017

Certain macrophage populations limit norepinephrine-induced lipolysis in adipose tissues in response to aging or obesity.
Role of ECMO in congenital diaphragmatic hernia
Authors: McHoney Merrill , Hammond Philip
Published: November 2017

Congenital diaphragmatic hernia (CDH) is typified morphologically by failure of diaphragmatic development with accompanying lung hypoplasia and persistent pulmonary hypertension of the newborn (PPHN). Patients who have labile physiology and low preductal saturations despite optimal ventilatory and inotropic support may be considered for extracorporeal membrane oxygenation (ECMO). Systematic reviews into the benefits of ECMO in CDH concluded that any benefit is unclear. Few randomised trials exist to demonstrate clear benefit and guide management. However, ECMO may have its uses in those that have reversibility of their respiratory disease. A few centres and networks have demonstrated an increase in survival rate by post hoc analysis (based on a difference in referral patterns with the availability of ECMO) in their series. One issue may be that of careful patient selection with regard to reversibility of pathophysiology. At present, there is no single test or prognostication that predicts reversibility of PPHN and criteria for referral for ECMO is undergoing continued refinement. Overall survival is similar between cannulation modes. There is no consensus on the time limit for ECMO runs. The optimal timing of surgery for patients on ECMO is difficult to definitively establish, but it seems that repair at an early stage (with careful perioperative management) is becoming less of a taboo, and may improve outcome and help with either coming off ECMO or decisions on withdrawal later. The provision of ECMO will continue to be evaluated, and prospective randomised trial are needed to help answer question of patient selection and management.
Implementation of the free maternity services policy and its implications for health system governance in Kenya
Authors: Pyone Thidar , Smith Helen , van den Broek Nynke
Published: November 2017

Introduction

To move towards universal health coverage, the government of Kenya introduced free maternity services in all public health facilities in June 2013. User fees are, however, important sources of income for health facilities and their removal has implications for the way in which health facilities are governed.

Objective

To explore how implementation of Kenya’s financing policy has affected the way in which the rules governing health facilities are made, changed, monitored and enforced.

Methods

Qualitative research was carried out using semistructured interviews with 39 key stakeholders from six counties in Kenya: 10 national level policy makers, 10 county level policy makers and 19 implementers at health facilities. Participants were purposively selected using maximum variation sampling. Data analysis was informed by the institutional analysis framework, in which governance is defined by the rules that distribute roles among key players and shape their actions, decisions and interactions.

Results

Lack of clarity about the new policy (eg, it was unclear which services were free, leading to instances of service user exploitation), weak enforcement mechanisms (eg, delayed reimbursement to health facilities, which led to continued levying of service charges) and misaligned incentives (eg, the policy led to increased uptake of services thereby increasing the workload for health workers and health facilities losing control of their ability to generate and manage their own resources) led to weak policy implementation, further complicated by the concurrent devolution of the health system.

Conclusion

The findings show the consequences of discrepancies between formal institutions and informal arrangements. In introducing new policies, policy makers should ensure that corresponding institutional (re)arrangements, enforcement mechanisms and incentives are aligned with the objectives of the implementers.
Evaluation of guidelines regarding surgical treatment of breast cancer using the AGREE Instrument: a systematic review
Authors: Lei Xin , Liu Fengtao , Luo Shuying , Sun Ya , Zhu Liling , Su Fengxi , Chen Kai , Li Shunrong
Published: November 2017

Objectives

Many clinical practice guidelines and consensus statements (CPGs/consensus statements) have been developed for the surgical treatments for breast cancer. This study aims to evaluate the quality of these CPGs/consensus statements.

Methods

We systematically searched the PubMed and EMBASE databases, as well as four guideline repositories, to identify CPGs and consensus statements regarding surgical treatments for breast cancer between January 2009 and December 2016. We used the Appraisal of Guidelines for Research and Evaluation (AGREE) instrument to assess the quality of the CPGs and consensus statements included. The overall assessment scores from the AGREE instrument and radar maps were used to evaluate the overall quality. We also evaluated some factors that may affect the quality of CPGs and consensus statements using the Mann-Whitney U test or Kruskal-Wallis H test. All analyses were performed using SPSS V.19.0. This systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Results

A total of 19 CPGs and four consensus statements were included. In general, the included CPGs/consensus statements (n=23) performed well in the ‘Scope and Purpose’ and ‘Clarity and Presentation’ domains, but performed poorly in the ‘Applicability’ domain. The American Society of Clinical Oncology (ASCO), National Institute for Health and Care Excellence (NICE), Scottish Intercollegiate Guidelines Network (SIGN), New Zealand Guidelines Group (NZGG) and Belgium Health Care Knowledge Centre (KCE) guidelines had the highest overall quality, whereas the Saskatchewan Cancer Agency, Spanish Society of Medical Oncology (SEOM), Japanese Breast Cancer Society (JBCS) guidelines and the D.A.C.H and European School of Oncology (ESO) consensus statements had the lowest overall quality. The updating frequency of CPGs/consensus statements varied, with the quality of consensus statements generally lower than that of CPGs. A total of six, eight and five CPGs were developed in the North American, European and Asian/Pacific regions, respectively. However, geographic region was not associated with overall quality.

Conclusions

The ASCO, NICE, SIGN, NZGG and KCE guidelines had the best overall quality, and the quality of consensus statements was generally lower than that of CPGs. More efforts are needed to identify barriers and facilitators for CPGs/consensus statement implementation and to improve their applicability.
Stoic beliefs and health: development and preliminary validation of the Pathak-Wieten Stoicism Ideology Scale
Authors: Pathak Elizabeth B , Wieten Sarah E , Wheldon Christopher W
Published: November 2017

Introduction

We developed and validated a new parsimonious scale to measure stoic beliefs. Key domains of stoicism are imperviousness to strong emotions, indifference to death, taciturnity and self-sufficiency. In the context of illness and disease, a personal ideology of stoicism may create an internal resistance to objective needs, which can lead to negative consequences. Stoicism has been linked to help-seeking delays, inadequate pain treatment, caregiver strain and suicide after economic stress.

Methods

During 2013–2014, 390 adults aged 18+ years completed a brief anonymous paper questionnaire containing the preliminary 24-item Pathak-Wieten Stoicism Ideology Scale (PW-SIS). Confirmatory factor analysis (CFA) was used to test an a priori multidomain theoretical model. Content validity and response distributions were examined. Sociodemographic predictors of strong endorsement of stoicism were explored with logistic regression.

Results

The final PW-SIS contains four conceptual domains and 12 items. CFA showed very good model fit: root mean square error of approximation (RMSEA)=0.05 (95% CI 0.04 to 0.07), goodness-of-fit index=0.96 and Tucker-Lewis Index=0.93. Cronbach’s alpha was 0.78 and ranged from 0.64 to 0.71 for the subscales. Content validity analysis showed a statistically significant trend, with respondents who reported trying to be a stoic ‘all of the time’ having the highest PW-SIS scores. Men were over two times as likely as women to fall into the top quartile of responses (OR=2.30, 95% CI 1.44 to 3.68, P<0.001). ORs showing stronger endorsement of stoicism by Hispanics, Blacks and biracial persons were not statistically significant.

Discussion

The PW-SIS is a valid and theoretically coherent scale which is brief and practical for integration into a wide range of health behaviour and outcomes research studies.
Incidence of shoulder dislocations in the UK, 1995–2015: a population-based cohort study
Authors: Shah Anjali , Judge Andrew , Delmestri Antonella , Edwards Katherine , Arden Nigel K , Prieto-Alhambra Daniel , Holt Tim A , Pinedo-Villanueva Rafael A , Hopewell Sally , Lamb Sarah E , Rangan Amar , Carr Andrew J , Collins Gary S , Rees Jonathan L
Published: November 2017

Objective

This cohort study evaluates the unknown age-specific and gender-specific incidence of primary shoulder dislocations in the UK.

Setting

UK primary care data from the Clinical Practice Research Datalink (CPRD) were used to identify patients aged 16–70 years with a shoulder dislocation during 1995–2015. Coding of primary shoulder dislocations was validated using the CPRD general practitioner questionnaire service.

Participants

A cohort of 16 763 patients with shoulder dislocation aged 16–70 years during 1995–2015 were identified.

Primary outcome measure

Incidence rates per 100 000 person-years and 95% CIs were calculated.

Results

Correct coding of shoulder dislocation within CPRD was 89% (95% CI 83% to 95%), and confirmation that the dislocation was a ‘primary’ was 76% (95% CI 67% to 85%). Seventy-two percent of shoulder dislocations occurred in men. The overall incidence rate in men was 40.4 per 100 000 person-years (95% CI 40.4 to 40.4), and in women was 15.5 per 100 000 person-years (95% CI 15.5 to 15.5). The highest incidence was observed in men aged 16–20 years (80.5 per 100 000 person-years; 95% CI 80.5 to 80.6). Incidence in women increased with age to a peak of 28.6 per 100 000 person-years among those aged 61–70 years.

Conclusions

This is the first time the incidence of shoulder dislocations has been studied using primary care data from a national database, and the first time the results for the UK have been produced. While most primary dislocations occurred in young men, an unexpected finding was that the incidence increased in women aged over 50 years, but not in men. The reasons for this are unknown. Further work is commissioned by the National Institute for Health Research to examine treatments and predictors for recurrent shoulder dislocation.

Study registration

The design of this study was approved by the Independent Scientific Advisory Committee (15_260) for the Medicines & Healthcare products Regulatory Agency.