bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructural Evolution and Protrusion Simulations of Cu-TSVs Under Different Loading Conditions
Authors: Liu Jinxin , Huang Zhiheng , Conway Paul P. , Liu Yang 
Published: September 2019

Abstract
Thermal stress-induced protrusions of copper through-silicon-vias (Cu-TSVs) during thermal processing pose substantial reliability concerns in three-dimensional (3D) system integration. In this study, a phase-field-crystal (PFC) model is used to investigate the protrusions and microstructural evolutions of blind Cu-TSVs under different loading conditions. Protrusions are observed only when the TSVs are under εx, εy, and γxy, whereas no protrusions are observed when the TSVs are subjected to pure shear strains γyx. The simulation results suggest that the grains in the top layer of a TSV contribute more to both the protrusion profile and the protrusion height than the grains in the lower layers. Moreover, the protrusion is larger when the misorientation among the grains is larger and the grain size along the y-direction is smaller. In addition, a phenomenological model linking protrusion and microstructural factors and a visual guide from the viewpoint of plastic flow are provided to understand the origins of Cu-TSV protrusion.
Magnification Factor Mk and its Parametric Solutions for Fatigue Crack Growth Assessment of Flaws at Weld Root Toes in Girth Welds
Authors: Zhang Yan-Hui , London Tyler , DeBono Damaso 
Published: September 2019

Abstract
To account for the effect of the stress concentration factor (SCF) at the weld toe on stress intensity factor range ΔK, a magnification factor Mk is used. The existing Mk solutions given in BS 7910 were developed for the fatigue assessment of flaws at the toes of fillet and butt welds and may not be suitable for assessing flaws at single-sided girth weld root toes, where fatigue cracking often initiates and the weld width is relatively small. Finite element (FE) modeling was performed to determine a 2D Mk solution for engineering critical assessment (ECA) of a flaw at the weld root bead toe. The weld root bead profile was uniquely characterized by five variables including weld root bead width, weld root bead height, hi-lo, weld root bead angle, and weld root bead radius. Following a parametric sensitivity study, defect size, weld root bead height, and hi-lo were identified as the governing parameters. A total of 6000 FE simulations was performed, covering different combinations of weld root bead height and hi-lo. A series of automation scripts were developed in the python programming language and the Mk solution for each type of defect model was developed and provided in a parametric equation. The accuracy of the 2D Mk solutions was confirmed by the experimental data. It was found that the methods and Mk solutions currently recommended in BS 7910 and DNVGL-RP-F108 are inappropriate for assessing a flaw at a girth weld root toe.
Elevated-Temperature Wear Characteristics and Mild-Severe Wear Transition in the Mg–10.1Gd–1.4Y–0.4Zr Alloy
Authors: An J. , Zhao W. , Feng C. Q. 
Published: September 2019

Abstract
Dry sliding wear characteristics of the as-cast Mg–10.1Gd–1.4Y–0.4Zr alloy were investigated at 3.0 m/s within a temperature range of 20–200 °C on a pin-on-disc type wear testing machine. Wear rates were acquired and plotted against load at each test temperature. There existed a turning point on the wear rate versus load curve at each test temperature; it corresponded to the mild-severe wear transition. The wear mechanisms were confirmed through morphological and compositional analysis of worn surfaces. An elevated-temperature wear mechanism transition map was drawn, in which mild and severe wear regions were indicated. The differences in microstructure as well as microhardness in subsurfaces were compared between samples worn in the two different regions. The dynamic recrystallization (DRX) softening of the surface material was found to be responsible for mild-severe wear transition. An approximately linear relationship was found between the transition load and test temperature, suggesting that mild-severe wear transition of the alloy still follows a surface temperature criterion even at elevated temperatures. The critical surface temperature is thought of to be the DRX temperature of the alloy. It is approximately 279.3 °C based on the linearly fitting analysis of the transition load versus test temperature.
Thermo-Chemo-Poromechanical Modeling of the Anode Mixture During the Baking Process: Constitutive Laws and Governing Equations
Authors: Chen Bowen , Chaouki Hicham , Picard Donald , Ziegler Donald , Alamdari Houshang , Fafard Mario 
Published: September 2019

Abstract
Aluminum is reduced from alumina by the Hall–Héroult electrolysis process in which the anode is utilized as the positive electrode. The quality of the prebaked anode plays a crucial rule in the efficiency of the aluminum electrolysis process. To produce high-quality anodes in the aluminum industry, the anode baking process calls for a deep understanding of mechanisms that govern the evolution of the anode mixture properties under the high-temperature condition. Therefore, the aim of this paper is to establish a thermo-chemo-poromechanical model for the baking anode by using the theory of reactive porous media based on the theory of mixtures within the thermodynamic framework. For this purpose, an internal state variable called “shrinking index” is defined to characterize the chemical progress of the pitch pyrolysis in the anode skeleton, and the Clausius–Duhem inequality is developed according to the Lagrangian formalism. By introducing a reduced Green–Lagrange strain tensor, a Lagrangian free energy is formulated to found a set of state equations. Then, the thermodynamic dissipation for this pyrolyzing solid–gas mixture is derived, and a constitutive model linking the chemical pyrolysis with the mechanical behavior is achieved. A dissipation potential is consistently defined to ensure the non-negativeness of the thermodynamic dissipation and to obtain the constitutive laws for viscous behaviors. Field equations governing the volatile diffusion and the heat transfer through the draining mixture body are derived from the entropy balance.
Dynamical Modeling and Control of Modular Snake Robots With Series Elastic Actuators for Pedal Wave Locomotion on Uneven Terrain
Authors: Koopaee Mohammadali Javaheri , Pretty Christopher , Classens Koen , Chen XiaoQi 
Published: September 2019

Abstract
This paper introduces the equations of motion of modular 2D snake robots moving in vertical plane employing Series Elastic Actuators (SEAs). The kinematics of such 2D modular snake robot is presented in an efficient matrix form and Euler–Lagrange equations are constructed to model the robot. Moreover, using a spring-damper contact model, external contact forces, necessary for modeling pedal wave motion (undulation in the vertical plane) are taken into account, which unlike existing methods can be used to model the effect of multiple contact points. Using such a contact model, pedal wave motion of the robot is simulated and the torque signal measured by the elastic element from the simulation and experimentation are used to show the validity of the model. Moreover, pedal wave locomotion of such robot on uneven terrain is also modeled and an adaptive controller based on torque feedback in gait parameter's space with optimized control gain is proposed. The simulation and experimentation results showed the efficacy of the proposed controller as the robot successfully climbed over a stair-type obstacle without any prior knowledge about its location with at least 24.8% higher speed compared with non-adaptive motion.
Evaluation of Compressor Blading With Blade End Slots and Full-Span Slots in a Highly Loaded Compressor Cascade
Authors: Tang Yumeng , Liu Yangwei , Lu Lipeng 
Published: September 2019

Abstract
Blade end slots were proposed to control corner separation in a highly loaded compressor cascade in our previous studies. This study focuses on the evaluation of compressor blading with blade end slots and full-span slots. First, the two-dimensional configuration performance is evaluated both for the datum and slotted profiles. The slotted configuration could effectively suppress separation, especially under positive incidence conditions when the separation is large. Thus, two three-dimensional blading with full-span slots and blade end slots (20% span height from the endwall) are compared. Results show that blading with full-span slots could effectively reduce the loss and enlarge pressure rise under relative high incidence angles, while blading with blade end slots could effectively reduce the loss and enlarge pressure rise above an incidence angle of −4 deg. Blading with slots alters the flow structures and reorganizes the flow in the blade end regions. The self-adaptive jets from the slots reenergize the low-momentum flow downstream and restrain its migration toward the mid-span, so that the corner separation is reduced and the performance is enhanced. The loss for the end slotted blade is lower than that of the full-span slotted blade under incidence angles within 4 deg. This is because the additional mixing loss of the jet and the main flow are caused by the full-span slots at the mid-span regions where the flow remains attached for the blade end slots.
Increasing the Measuring Accuracy of a Sensory Swing Clamp by Multi-Sensor Evaluation
Authors: Denkena Berend , Bergmann Benjamin , Kiesner Johann 
Published: September 2019

Abstract
The growing flexibility of modern production systems complicates the quality assurance and process safety of mechanical processing. As an import component of milling machines, the workpiece clamping systems plays a quality-determining role within every milling process. Thus, a sensory workpiece clamping system that utilizes sensory swing clamps was developed in former research work in order to provide monitoring capabilities. This contribution deals with the experimental analysis of the multiple integrated sensors of the sensory swing clamp and the characterization of their measuring capability toward different measurands. By means of the stepwise linear regression method, different models were developed that enable the determination of the clamping force, the hydraulic pressure, and the piston position. The results verify that the multi-sensor evaluation significantly increases the measuring accuracy of a sensory swing clamp. Thus, the measuring accuracy is measurable with a standard deviation of 0.05 MPa for the hydraulic pressure, 101 N for the clamping force, and 0.62 mm for the piston position. Furthermore, the practicability and flexible use at varying boundary conditions is proved.
Effects of Damaged Fiber Ropes on the Performance of a Hybrid Taut-Wire Mooring System
Authors: Lian Yushun , Yim Solomon C. , Zheng Jinhai , Liu Haixiao , Zhang Nan 
Published: September 2019

Abstract
In this study, effects of damage levels of fiber ropes on the performance of a hybrid taut-wire mooring system are investigated. The analysis is performed using a numerical floating production storage and offloading (FPSO) model with a hybrid mooring system installed in 3000 m of water depth. An in-depth study was conducted using the numerical model, the dynamic stiffness equation of damaged fiber ropes, the time-domain dynamic theory, the rainflow cycle counting method, and the linear damage accumulation rule of Palmgren-Miner. Results indicate that, in a mooring line with an increasing damage level, the maximum tension decreases, while the offset of the FPSO increases. Particularly, when a windward mooring line failure occurs, in addition to the significant increase in the offset of the FPSO, the maximum tension, tension range, and annual fatigue damage levels of the remaining lines adjacent to the failed also increase significantly. The present work can be of great benefit to the evaluation of the offset of the floating platform, the tension response, and the service life of the hybrid mooring systems.
A Fully Compliant Tristable Mechanism Employing Both Tensural and Compresural Segments
Authors: Chen Guimin , Han Qi , Jin Kaifang 
Published: September 2019

Abstract
A multistable compliant mechanism is a device that can hold several distinct positions through the storage and release of the strain energy associated with deflections of the flexible members. This self-locking capability can benefit many applications such as threshold acceleration sensing, overload protection, and shape reconfiguration. This work presents a novel class of fully compliant tristable mechanisms called tensural–compresural tristable mechanisms (TCTMs), which forms three stable equilibrium positions through unique utilization of both tensural segments and compresural segments. To identify feasible designs, a kinetostatic model is developed using the chained beam-constraint-model (CBCM) for both tensural segments and compresural segments. Two TCTM designs accompanied with a prototype are presented to demonstrate the feasibility of this new tristable configuration and the effectiveness of the kinetostatic model.
Optimal Sensor Placement Methods in Active High Power Density Electronic Systems With Experimental Validation
Authors: Peddada Satya R. T. , Tannous Pamela J. , Alleyne Andrew G. , Allison James T. 
Published: September 2019

Abstract
Increasing the efficiency and density of power electronic systems (PESs) is an important objective for many high-impact applications, such as electric vehicle charging and aircraft electrification. Due to compactness and high heat dissipation, careful thermal monitoring of such PESs is required. Strategic placement of temperature sensors can improve the accuracy of real-time temperature distribution estimates. Enhanced temperature estimation supports increased power throughput and density because PESs can be operated in a less conservative manner while still preventing thermal failure. This article presents new methods for temperature sensor placement for 2- and 3-dimensional PESs that (1) improve computational efficiency (by orders of magnitude in at least one case), (2) support the use of more accurate evaluation metrics, and (3) are scalable to high-dimension sensor placement problems. These methods are tested via sensor placement studies based on a single-phase flying capacitor multi-level (FCML) prototype inverter. Information-based metrics are derived from a resistance-capacitance (RC) lumped parameter thermal model. Other more general metrics and system models are possible through the application of a new continuous relaxation strategy introduced here for placement representation. A new linear programming (LP) formulation is presented that is compatible with a particular type of information-based metric. This LP strategy is demonstrated to support an efficient solution of finely discretized large-scale placement problems. The optimal sensor locations obtained from these methods were tested via physical experiments. The new methods and results presented here may aid the development of thermally aware PESs with significantly enhanced capabilities.
Study on Meta-Modeling Method for Performance Analysis of Digital Power Plant
Authors: Zhou Dengji , Wei Tingting , Ma Shixi , Zhang Huisheng , Huang Di , Jiang Ping , Lu Zhenhua 
Published: September 2019

Abstract
Digital power plant is the theory and method to improve the operating quality of power plant by quantifying, analyzing, controlling, and deciding the physical and working objects of power plants in the whole life cycle. And the foundation of digital power plant is system modeling and performance analysis. However, there are some problems in the process of modeling establishment and performance analysis. For instance, each component has different dimensions and different types of mathematical description, and the data or information used for modeling are defined differently and belong to different enterprises, who do not want to share their information. Meta-modeling is a potential method to solve these problems. It defines the specification to describe different kinds of elements and the relationship between different elements. In this paper, the collaborative modeling and simulation platform for digital power plant has been established based on the meta-modeling method and the performance of the target power plant has been analyzed from different aspects via field data. The meta-modeling method consists of three parts: syntax definition, model development, and algorithm definition. In the comparative study between the meta-model and the traditional model, maximum average errors of the two methods are 8.72% and 4.74%, which reveals the high accuracy of the meta-modeling-based model. The result shows that the modeling and simulation platform for power plants can be used to reduce costs, decrease equipment failure rate, and improve plant output, so as to guarantee the safety and increase economics.
Predicting Cycle-to-Cycle Variation With Concurrent Cycles in a Gasoline Direct Injected Engine With Large Eddy Simulations
Authors: Probst Daniel M. , Wijeyakulasuriya Sameera , Pomraning Eric , Kodavasal Janardhan , Scarcelli Riccardo , Som Sibendu 
Published: September 2019

Abstract
High cycle-to-cycle variation (CCV) is detrimental to engine performance, as it leads to poor combustion and high noise and vibration. In this work, CCV in a gasoline engine is studied using large eddy simulation (LES). The engine chosen as the basis of this work is a single-cylinder gasoline direct injection (GDI) research engine. Two stoichiometric part-load engine operating points (6 brake mean effective pressure (BMEP) and 2000 revolutions per minute) were evaluated: a nondilute (0% exhaust gas recirculation (EGR)) case and a dilute (18% EGR) case. The experimental data for both operating conditions had 500 cycles. The measured CCV in indicated mean effective pressure (IMEP) was 1.40% for the nondilute case and 7.78% for the dilute case. To estimate CCV from simulation, perturbed concurrent cycles of engine simulations were compared with consecutively obtained engine cycles. The motivation behind this is that running consecutive cycles to estimate CCV is quite time consuming. For example, running 100 consecutive cycles requires 2–3 months (on a typical cluster); however, by running concurrently, one can potentially run all 100 cycles at the same time and reduce the overall turnaround time for 100 cycles to the time taken for a single cycle (2 days). The goal of this paper is to statistically determine if concurrent cycles, with a perturbation applied to each individual cycle at the start, can be representative of consecutively obtained cycles and accurately estimate CCV. 100 cycles were run for each case to obtain statistically valid results. The concurrent cycles began at different timings before the combustion event, with the motivation to identify the closest time before spark to minimize the run time. Only a single combustion cycle was run for each concurrent case. The calculated standard deviation of peak pressure and coefficient of variance (COV) of IMEP were compared between the consecutive and concurrent methods to quantify CCV. It was found that the concurrent method could be used to predict CCV with either a velocity or numerical perturbation. Both a large and small velocity perturbations were compared, and both produced correct predictions, implying that the type of perturbation is not important to yield a valid realization. Starting the simulation too close to the combustion event, at intake valve close (IVC) or at spark timing, underpredicted the CCV. When concurrent simulations were initiated during or before the intake even, at start of injection (SOI) or earlier, distinct and valid realizations were obtained to accurately predict CCV for both operating points. By simulating CCV with concurrent cycles, the required wall clock time can be reduced from 2–3 months to 1–2 days. In addition, the required core-hours can be reduced up to 41%, since only a portion of each cycle needs to be simulated.
A History Matching Framework to Characterize Fracture Network and Reservoir Properties in Tight Oil
Authors: Shiqian Xu , Yuyao Li , Yu Zhao , Sen Wang , Qihong Feng 
Published: September 2019

Abstract
Accurately characterizing hydraulic fracture network and tight oil reservoir properties can lay the foundation for the production forecast and development design. In this work, we proposed a history matching framework for tight oil. We first use the Hough transform method to characterize complex fracture network from microseismic data. Then, we put the fracture network into an embedded discrete fracture model (EDFM) to build a tight oil reservoir simulation model. After that, we further couple whale optimization algorithm (WOA) and EDFM to match the field production data. In this way, we can accurately estimate reservoir properties, including matrix permeability and porosity, as well as fracture permeability. We apply the framework to two-field applications in China. One is fractured vertical well in the Songliao Basin of Daqing oilfield. The other one is multi-stage fractured horizontal well in the Jimsar Sag of the Xinjiang oilfield. Results show that if we do not consider tight oil characteristics, the estimated fracture permeability, matrix permeability, and matrix porosity will underestimate 73%, 20%, and 47%, respectively. Because we apply WOA to history matching for the first time, we compare the performance of WOA with ensemble–smoother with multiple data–assimilation (ES-MDA). When we fit six parameters, ES-MDA performs better than WOA. However, when we fit three parameters, WOA performs better than ES-MDA. In addition, for engineering problem, WOA performs well on both convergence speed and stability. Therefore, WOA is recommended in the future application of history matching.
Social work and social justice: The relationship between fitness to practise and criminal convictions for non-violent activism
Authors: Williams Nathan J. 
Published: September 2019

INTRODUCTION: Social work as a profession is underpinned by ideas of social justice and human rights, and that social workers have an ethical obligation to uphold these ideas. Social workers have a history of engagement in non-violent social justice activism (NVSJA), and a proud record of achieving social change in Aotearoa New Zealand. However, having a criminal conviction for engaging in NVSJA can be a barrier to social work registration in Aotearoa New Zealand.APPROACH: An exploration of current research around NVSJA and social work registration was conducted. Along with an examination of the Social Workers Registration Board’s (SWRB’s) Fit and Proper Person Policy Statement, with a consideration on the reporting of acts of NVSJA and social workers by the media.CONCLUSION: Those who engage in NVSJA are often likely to gain criminal convictions. This creates a potential barrier for social workers who go beyond the rhetoric and fight for social justice, in a macro and practical sense, from gaining registration. This has become additionally important since the Social Workers Registration Legislation Act (2019) passed and with registration becoming mandatory two years after the Act gained royal assent. There is a need for a change to the Fit and Proper Person Policy Statement so that the SWRB is better able to support social workers who are standing for what social work is all about, or at least, what social work is stated to be all about.