bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reliability Analysis of Solder Joints on Rigid-Flexible Printed Circuit Board for MEMS Pressure Sensors Under Combined Temperature Cycle and Vibration Loads With Continuously Monitored Electrical Signals
Authors: Wang Xiaoping , Yang Jun , Liu Xiaogang , Zheng Panpan , Song Qinglin , Song Bin , Liu Sheng 
Published: January 2021

Abstract
The reliability of lead-free solder joints on flexible printed circuit board (PCB) has created significant new challenges in the industry, especially in automotive electronics, and possibly for future wearable electronics. In the automotive industry, thermal cycling test and random vibration test need to be conducted to certify every electronic product to be used in harsh automotive environments. In order to accelerate the testing time, we may need to subject the electronic components, in particular, sensors to both loadings such as thermal cycling and vibration. During all the experiments, the electrical signals of each specimen were continuously monitored by using an event detector. One advantage of this method is that any individual soldering interconnect failure will result in the diagnostic signal of the circuit, which could be detected in real-time. A simulation was used to confirm the possibility of the stress concentration location caused by the vibration and thermal cycling loads. The influence of vibration frequency and acceleration on the vibration fatigue life of solid joints was investigated. In this paper, the submodeling technique was used to construct the finite element model of the rigid-flexible printed circuit board (rigid-flexible PCB) coupled with a MEMS pressure sensor subjected to temperature cycle and random vibration loadings. The research results are helpful to effectively characterize the performance of the MEMS sensors under both thermal cycling test and vibration test. Two kinds of land shapes and two kinds of PCB assemblies were selected. In order to investigate the crack growth in the solder joint, the solder joint is sliced and the crack on the cross section of the solder joint was observed. Results of finite element modeling analysis were consistent with the experimental results. Two design parameters have been identified in our research as being important to soldering usage in automotive environments: pad type (teardrop versus nonteardrop) and pad size (big versus small, matching size for Cu-wire and pad). Experimental results also showed that the solder joint with a big land shape presented a relatively good thermal fatigue resistance.
Investigation of Flow Separation Characteristics in a Pump as Turbines Impeller Under the Best Efficiency Point Condition
Authors: Lin Tong , Li Xiaojun , Zhu Zuchao , Xie Renhua , Lin Yanpi 
Published: January 2021

Abstract
The impeller, which is the main energy conversion component of a pump as turbine (PAT), is designed for pumping mode, and its internal flow characteristics are quite complicated even at the best efficiency point (BEP) of the turbine mode. This study aims to investigate the flow separation characteristics in a PAT impeller under the BEP condition by numerical method. The hydraulic performance and transient pressure characteristics of PAT predicted numerically were verified through experimentation. The surface friction lines and flow topological structure were applied to diagnose the flow separation at the surface of the blade. The relationship between flow topological structure and vortex in the impeller and static pressure at the blade were analyzed. Analysis results show that the backflow and open flow separation are observed significantly in the leading region and near the shroud of the trailing region of suction side. The passage vortex always appears near the spiral node. The saddle point and spiral node correspond to the peak position of adverse pressure and the lowest position between two peak values of the static pressure of the blade, respectively. The inflow conditions of blade and shape of the trailing edge significantly influence the flow separations in the impeller.
Tensile Response of a Flexible Pipe With an Incomplete Tensile Armor Layer
Authors: Zhu Xiaohua , Lei Qinglong , Meng Yu , Cui Xiaoxuan 
Published: January 2021

Abstract
Unbonded flexible pipes are widely utilized in the exploitation of offshore oil and gas resources. They are connected to two of the most critical types of system: floating production platforms and underwater production systems. However, if some tensile armor wires are substituted by cables or broken, the tensile armor layer will be incomplete, which seriously reduces the safety and reliability of the flexible pipe. In the present study, models of a flexible pipe with a complete tensile layer and with the tensile layer partially missing were established. The error for the tensile stiffness obtained by the finite element model of an intact flexible pipe was only 1% compared with experimental results. Because the load borne by the inner tensile armor layer is larger under tension than that borne by the outer tensile armor layer, the loss of inner tensile armor wires has a greater impact on the tensile properties. The maximum axial elongation of the flexible pipe increases with the number of missing inner tensile armor wires as a cubic polynomial. If the distribution of the missing armor wires is too dense, a stress concentration and local bending may occur, which will reduce the tensile strength of the flexible pipe.
Multi-Objective Optimal Design of an Active Aeroelastic Cascade Control System for an Aircraft Wing With a Leading and Trailing Control Surface
Authors: Chen Yuekun , Sardahi Yousef 
Published: January 2021

Abstract
This paper presents a multi-objective optimal design of cascade controllers applied to an aircraft wing with a leading and trailing control surface driven by electromagnetic actuators (EMAs). The design of the control system is decoupled into an inner (slave or secondary) and outer (master or primary) control algorithm. The master control algorithm is applied to the dynamics of the wing and its ailerons while two salve control loops are designed for the two EMAs. Then, a multi-objective and optimal design of the control algorithms is carried out. Three objectives are considered : 1) the speed of response of the slave controlled system must be faster than that of the master one, 2) the controlled system must be robust against external upsets, and 3) optimal energy consumption. The multi-objective optimization problem (MOP) is solved by the non-dominated sorting genetic algorithm (NSGA-II), which is one of the widely algorithms in solving MOPs. The setup parameters of the primary and secondary control algorithms are tuned during the optimization and the design objectives are evaluated. The solution of the MOP is a set of optimal cascade controllers that represent the trade-offs among the design objectives. Computer simulations show that the design objectives are achieved. However, some of the optimal solutions are practically in-feasible because they respond poorly to external disturbances. Presented study may become the basis for multi-objective optimal design of active aeroelastic control systems.
Speed Trajectory Generation for Energy-Efficient Connected and Automated Vehicles
Authors: Jan Lung En , Zhao Junfeng , Aoki Shunsuke , Bhat Anand , Chang Chen-Fang , Rajkumar Ragunathan (Raj) 
Published: January 2021

Abstract
Connected and automated vehicles (CAVs) have real-time knowledge of the immediate driving environment, actions to be taken in the near future and information from the cloud. This knowledge, referred to as preview information, enables CAVs to drive safely, but can also be used to minimize fuel consumption. Such fuel-efficient transportation has the potential to reduce aggregate fuel consumption by billions of gallons of gas every year in the U.S. alone. In this paper, we propose a planning framework for use in CAVs with the goal of generating fuel-efficient vehicle trajectories. By utilizing on-board sensor data and vehicle-to-infrastructure (V2I) communications, we leverage the computational power of CAVs to generate eco-friendly vehicle trajectories. The planner uses an eco-driver model and a predictive cost-based search to determine the optimal speed profile for use by a CAV. To evaluate the performance of the planner, we introduce a co-simulation environment consisting of a CAV simulator, Matlab/Simulink and a CAV software platform called the InfoRich Eco-Autonomous Driving (iREAD) system. The planner is evaluated in various urban traffic scenarios based on real-world road network models provided by the National Renewable Energy Laboratory (NREL). Simulations show an average savings of 14.5% in fuel consumption with a corresponding increase of 2% in travel time using our method.
Advanced Dynamics Analysis of a Drilling Roller Reamer As a Rigid Multibody System
Authors: Adewuya Opeyemi 
Published: January 2021

Abstract
The roller-reamer tool is typically installed in an oil and gas well bottom hole drilling assembly (BHA) to ream or smoothen out rough, gouging and scored wellbore surfaces left from the drill bit cutting action. The rotational dynamics of the roller-reamer functionally combines reaming and stabilizing action as it is constrained to rotate in circular wellbores. The relative velocity method developed for dynamics analysis of planetary gears is first used to obtain the Newtonian velocity and acceleration equations, then with use of the Extended Hamilton’s principle, derive Lagrange equations of motion. Published works of dynamics simulations from numerical models typically idealize drillstrings as series of connected non-linear Euler-Bernoulli beam elements representing various components of a drillstring, for instance, stabilizers and roller reamers are modeled as point contacts. This idealization and lumped parameter model approximations of potential sources of dynamics dysfunction such as roller-reamers mask understanding of their behavior and opportunities for design improvements and further application optimization. Of particular interest in this work is comparison between the torque magnitudes generated by the drilling stabilizer and the roller-reamer. Phase portraits of angular velocity versus displacement — proxy for torque generated — from numerical simulations for torque-free, precession modes in oversized wellbores and applied external load states, offer insights into downhole operating dynamics of an essential component of oil and gas well bottom hole assembly (BHA) drilling assemblies.
Frequency-Amplitude Response of Subharmonic Resonance of One-Third Order of Electrostatically Actuated MEMS Circular Plates
Authors: Caruntu Dumitru I. , Beatriz Julio , Martinez Miguel 
Published: January 2021

Abstract
This work deals with the subharmonic resonance of one-third order of electrostatically actuated clamped MEMS circular plate resonators. The system consists of flexible MEMS circular plate parallel to a ground plate actuated only by AC voltage. Hard excitations due to large enough AC voltage of frequency near three-halves of the natural frequency of the MEMS plate resonator lead it into a subharmonic resonance. The partial differential equation describing the motion of the resonator is nondimensionalized and two reduced order models are developed. The first one consists of a one mode of vibration model which is solved using the Method of Multiple Scales (MMS). The frequency-amplitude response (bifurcation diagram) is predicted. Hard excitations were modeled by keeping the first term of the Taylor polynomial of the electrostatic force as a large term and the rest of them as small terms. The second model uses two modes of vibration, and it is solved through numerical integration. This produces time responses of the resonator. Both methods show a zero-amplitude steady-state stable branch for the entire range of resonant frequencies. Also, two branches, one unstable and one stable, with a saddle node bifurcation point are predicted for non-zero steady state amplitudes. One can notice that non-zero steady state amplitudes can be reached only from large enough initial amplitudes. Both methods are in agreement for amplitudes up to 0.7 of the gap. The effect of damping and voltage on the frequency response are reported. As the damping increases, the saddle-node bifurcation point and consequently the non-zero steady-state branches are shifted to larger amplitudes. As the voltage increases, the saddle-node bifurcation point and the non-zero branches are shifted to lower amplitudes and lower frequency.
Modeling Thermal Effects in DC-Motors Using Pseudo-Bond Graphs
Authors: Clemen Layne , Beckerman Alex 
Published: January 2021

Abstract
Motor selection is important in all mechatronic systems. This requires understanding how motor performance degrades as a function of system temperature. In this paper, bond graphs are used to develop two simple motor models that captures this performance degradation, specifically by modeling the changes in system resistance and the motor constant as a function of system temperature. In the first system, the entire motor is assumed to be one thermal mass while in the second, the rotor and stator are modeled as two thermal masses separated by an air gap. The calculation of system temperatures allow for relevant system parameters to be represented more accurately over long periods of operation. Either model is readily integrated into models of larger mechatronic systems, a task made more simple through the use of bond graphs. The results presented in this paper will help future engineers to appropriately size motors for mechatronic systems based on such considerations as steady state temperature response, low versus high load conditions, and ambient operating conditions.
Dynamic Prediction-Based Optical Localization of a Robot During Continuous Movement
Authors: Greenberg Jason N. , Tan Xiaobo 
Published: January 2021

Abstract
Localization of mobile robots is essential for navigation and data collection. This work presents an optical localization scheme for mobile robots during the robot’s continuous movement, despite that only one bearing angle can be captured at a time. In particular, this paper significantly improves upon our previous works where the robot has to pause its movement in order to acquire the two bearing angle measurements needed for position determination. The latter restriction forces the robot to work in a stop-and-go mode, which constrains the robot’s mobilitty. The proposed scheme exploits the velocity prediction from Kalman filtering, to properly correlate two consecutive measurements of bearing angles with respect to the base nodes (beacons) to produce location measurement. The proposed solution is evaluated in simulation and its advantage is demonstrated through the comparison with the traditional approach where the two consecutive angle measurements are directly used to compute the location.
Design, Modeling, and Identification of an Experimental Liquid-Level Control System: Enabling Research in Fault Diagnosis
Authors: Workneh Hilina T. , Raptis Ioannis A. 
Published: January 2021

Abstract
In this work we address the design and analysis challenge of a laboratory benchmark system, suited for testing and comparing model-based fault diagnosis algorithms. The motivation is the democratization of research in fault diagnosis, which is hindered by the lack of accessible data from real-world systems. A liquid-level control system with three interconnected storage tanks was selected for the physical process. The fault modes under consideration — liquid leak at the tanks — were planted in a manner that their impact can be measured and quantified. Commercially available sensing, actuating, and data acquisition electronic components were used for interfacing the monitoring unit (cyber part) with the process (physical part). A detailed description of the first-principles mathematical modeling is provided for deriving the state-space equations of the physical process. System identification, using elementary least-squares estimation, was performed to estimate the parameters of the parametric model using input/output data. The validation of the identified dynamic model and its agreement with the collected data showcase the capabilities of the proposed system for testing and comparing model-based fault diagnosis algorithms.
Six-year incidence and systemic associations of retinopathy in a multi-ethnic Asian population without diabetes
Authors: Gupta Preeti , Lamoureux Ecosse Luc , Sabanayagam Charumathi , Tham Yih-Chung , Tan Gavin , Cheng Ching-Yu , Wong Tien Yin , Cheung Ning 
Published: January 2021

PurposeWe described the 6-year incidence and changes of retinopathy, and their associated risk factors in a multi-ethnic Asian population without diabetes.MethodsWe included 4374 participants with non-diabetes from a population-based cohort, the Singapore Epidemiology of Eye Disease Study, with gradable retinal photographs at baseline and 6-year follow-up visit. Retinopathy was assessed according to the modified Airlie House classification system.ResultsOver the 6-year period, the cumulative rates were 2.5% (106/4279) for retinopathy incidence, 1.0% (1/95) for retinopathy progression and 68.4% (65/95) for retinopathy regression. In multivariable analysis, higher diastolic blood pressure (DBP) (risk ratio (RR)=1.02; 95% CI: 1.00 to 1.04; per 10 mm Hg increase in DBP) and wider retinal arteriolar calibre (RR=1.36; 95% CI: 1.13 to 1.63; per SD increase in central retinal artery equivalent) were associated with higher risk of incident retinopathy, while higher level of high-density lipoprotein (HDL) was associated with lower risk of incident retinopathy (RR=0.56; 95% CI: 0.32 to 0.99; per mmol/L increase in HDL). Compared with Chinese, Malays were more likely to have retinopathy regression (RR=1.63; 95% CI: 1.20 to 2.22), while overweight (RR=0.47; 95% CI: 0.26 to 0.84) and higher glycosylated haemoglobin (HbA1c) level (RR=0.58; 95% CI: 0.37 to 0.93; per per cent increase in HbA1c) were associated with lower likelihood of retinopathy regression.ConclusionRisk of developing retinopathy in Asians without diabetes is generally low. However, regression of retinopathy over time is common, suggesting that these retinopathy signs may reflect subclinical reversible microvascular dysfunction. Several metabolic risk factors are associated with incidence or regression of retinopathy, suggesting that good metabolic control may still be important in the management of non-diabetic retinopathy.
Activated intestinal muscle cells promote preadipocyte migration: a novel mechanism for creeping fat formation in Crohn’s disease
Authors: Mao Ren , Doyon Genevieve , Gordon Ilyssa O , Li Jiannan , Lin Sinan , Wang Jie , Le Thi Hong Nga , Elias Michael , Kurada Satya , Southern Brian , Olman Mitchell , Chen Minhu , Zhao Shuai , Dejanovic Dina , Chandra Jyotsna , Mukherjee Pranab K , West Gail , Van Wagoner David R , Fiocchi Claudio , Rieder Florian 
Published: January 2021

ObjectiveCreeping fat, the wrapping of mesenteric fat around the bowel wall, is a typical feature of Crohn’s disease, and is associated with stricture formation and bowel obstruction. How creeping fat forms is unknown, and we interrogated potential mechanisms using novel intestinal tissue and cell interaction systems.DesignTissues from normal, UC, non-strictured and strictured Crohn’s disease intestinal specimens were obtained. The muscularis propria matrisome was determined via proteomics. Mesenteric fat explants, primary human preadipocytes and adipocytes were used in multiple ex vivo and in vitro cell migration systems on muscularis propria muscle cell derived or native extracellular matrix. Functional experiments included integrin characterisation via flow cytometry and their inhibition with specific blocking antibodies and chemicals.ResultsCrohn’s disease muscularis propria cells produced an extracellular matrix scaffold which is in direct spatial and functional contact with the immediately overlaid creeping fat. The scaffold contained multiple proteins, but only fibronectin production was singularly upregulated by transforming growth factor-β1. The muscle cell-derived matrix triggered migration of preadipocytes out of mesenteric fat, fibronectin being the dominant factor responsible for their migration. Blockade of α5β1 on the preadipocyte surface inhibited their migration out of mesenteric fat and on 3D decellularised intestinal tissue extracellular matrix.ConclusionCrohn’s disease creeping fat appears to result from the migration of preadipocytes out of mesenteric fat and differentiation into adipocytes in response to an increased production of fibronectin by activated muscularis propria cells. These new mechanistic insights may lead to novel approaches for prevention of creeping fat-associated stricture formation.
The variational method, backreactions, and the absorption probability in Wald type problems
Authors: Düztaş Koray 
Published: January 2021

AbstractWe argue that the variational method in Wald type thought experiments, involves order of magnitude problems when one imposes the fact that $$\delta M$$

δ
M

is inherently a first order quantity itself. One observes that the contribution of the second order perturbations is actually of the fourth order. Therefore backreactions have to be explicitly calculated. Here, we re-consider the overspinning problem for Kerr–Newman black holes interacting with test fields. We calculate the backreaction effects due to the induced increase in the angular velocity of the event horizon, which brings a partial solution to the overspinning problem. To bring an ultimate solution, we argue that the absorption probability should be taken into account in Wald type problems where black holes interact with test fields. This fundamentally alters the course of the analysis of the thought experiments. Due to the fact that a small fraction of the challenging modes is absorbed by the black holes, overspinning is prevented for both nearly extremal and extremal cases. Some extreme cases are easily fixed by backreaction effects. The arguments do not apply to the generic overspinning by fermionic fields for which the absorption probability is positive definite.