bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal fishery with coastal catch
Authors: Grass Dieter , Uecker Hannes , Upmann Thorsten
Published: September 2019

In many spatial resource models, it is assumed that an agent is able to harvest the resource over the complete spatial domain. However, agents frequently only have access to a resource at particular locations at which a moving biomass, such as fish or game, may be caught or hunted. Here, we analyze an infinite time‐horizon optimal control problem with boundary harvesting and (systems of) parabolic partial differential equations as state dynamics. We formally derive the associated canonical system, consisting of a forward–backward diffusion system with boundary controls, and numerically compute the canonical steady states and the optimal time‐dependent paths, and their dependence on parameters. We start with some one‐species fishing models, and then extend the analysis to a predator–prey model of the Lotka–Volterra type. The models are rather generic, and our methods are quite general, and thus should be applicable to large classes of structurally similar bioeconomic problems with boundary controls.

Recommedations for Resource Managers

Just like ordinary differential equation‐constrained (optimal) control problems and distributed partial differential equation (PDE) constrained control problems, boundary control problems with PDE state dynamics may be formally treated by the Pontryagin's maximum principle or canonical system formalism (state and adjoint PDEs).

These problems may have multiple (locally) optimal solutions; a first overview of suitable choices can be obtained by identifying canonical steady states.

The computation of canonical paths toward some optimal steady state yields temporal information about the optimal harvesting, possibly including waiting time behavior for the stock to recover from a low‐stock initial state, and nonmonotonic (in time) harvesting efforts.

Multispecies fishery models may lead to asymmetric effects; for instance, it may be optimal to capture a predator species to protect the prey, even for high costs and low market values of the predators.
Novel KIT mutation presenting as marked lentiginosis
Authors: Tran Alain K. , Pearce Annette , López‐Sánchez Marcos , Pérez‐Jurado Luis A. , Barnett Christopher
Published: September 2019

Although lentigines are usually benign, they can be associated with a number of genetic syndromes in which neoplasms and other multi‐system pathological processes occur. Here, we report the case of a 6‐year‐old girl who presented with atypical lentiginosis and hyperpigmentation caused by a de novo genetic variant in the KIT gene.
Lymphocyte subset at time of Epstein‐Barr viremia post‐allogeneic hematopoietic stem cell transplantation in children may predict development of post‐transplant lymphoproliferative disease: CD8:CD20 ratio as a sensitive predictor
Authors: Althubaiti Sami , Ali Salah , Renzi Samuele , Krueger Joerg , Chiang Kuang-Yueh , Schechter Tal , Punnett Angela , Ali Muhammad
Published: September 2019

EBV–associated PTLD following allogeneic HSCT is a serious complication associated with significant mortality. In this retrospective study, we evaluated whether lymphocyte subset numbers and CD8:CD20 ratio at time of EBV viremia in children undergoing allogeneic HSCT could predict development of PTLD. Absolute lymphocyte count, lymphocyte subsets, and CD8:CD20 ratio at the time of EBV viremia were analyzed. Patients who were treated preemptively with rituximab for high blood EBV viral load were excluded. Out of 266 patients transplanted during the study period, 26 patients were included in the analysis. Patients were divided into two cohorts; cohort 1 included patients with EBV‐associated PTLD (n = 5; four with proven, one with probable PTLD). Cohort 2 included patients with EBV viremia without PTLD (n = 21). Lymphocyte recovery was slower in the PTLD group. CD8:CD20 ratio was significantly lower in the PTLD group (median 0.15) compared to the non‐PTLD group (median 2.4, P = .012). Using the ROC curve and 1 as the cutoff value, CD8:CD20 ratios were analyzed. In the PTLD group, 4/5 patients (80%) had a ratio <1 whereas in the non‐PTLD group, all 21 patients had a ratio >1. Sensitivity and specificity were 80% and 100%, respectively. Negative and PPVs were 95% and 100%, respectively. Profoundly low T‐cell count and CD8:CD20 ratio may be used to predict development of PTLD in the context of EBV viremia in children post‐allogeneic HSCT. Further studies are needed to validate this finding.
Arabidopsis OTU1, a linkage‐specific deubiquitinase, is required for endoplasmic reticulum‐associated protein degradation
Authors: Zang Yuepeng , Gong Yingya , Wang Qian , Guo Huiping , Xiao Wei
Published: September 2019

Endoplasmic reticulum (ER)‐associated degradation (ERAD) is part of the ER protein quality‐control system (ERQC), which is critical for the conformation fidelity of most secretory and membrane proteins in eukaryotic organisms. ERAD is thought to operate in plants with core machineries highly conserved to those in human and yeast; however, little is known about the plant ERAD system. Here we report the characterization of a close homolog of human OTUB1 in Arabidopsis thaliana, designated as AtOTU1. AtOTU1 selectively hydrolyzes several types of ubiquitin chains and these activities depend on its conserved protease domain and/or the unique N‐terminus. The otu1 null mutant is sensitive to high salinity stress, and particularly agents that cause protein misfolding. It turns out that AtOTU1 is required for the processing of known plant ERAD substrates such as barley powdery mildew O (MLO) alleles by virtue of its association with the CDC48 complex through its N‐terminal region. These observations collectively define AtOTU1 as an OTU domain‐containing deubiquitinase involved in Arabidopsis ERAD.
Analysis of Normal Elastic Contact Stiffness of Rough Surfaces Based on Ubiquitiform Theory
Authors: Shang Shaofei , Cao Xiaoshan , Liu Zhiqiang , Shi Junping
Published: September 2019

In this study, the normal stiffness of elastic contact between rough surfaces with asperities following Gaussian distribution is investigated using ubiquitiform theory, developed from fractal theory. In the generalized ubiquitiformal Sierpinski carpet model, the rough surface including contact asperity is controlled for, given the lower bound to scale invariance of rough surfaces. Considering the stiffness of a single asperity deduced from the Hertz contact model, we deduce the theoretical relation between the normal stiffness and the elastic contact of rough surfaces based on ubiquitiform theory. The results show that the normal contact stiffness of a rough surface increases as the normal load rises. If the ubiquitiformal complexity of a rough surface increases or the lower bound to scale invariance of a rough surface decreases, the normal contact stiffness of the rough surface should increase. The larger the ubiquitiformal complexity of a rough surface is, the more obvious the impact of the lower bound to scale invariance on the normal contact stiffness of the rough surface becomes. The results based on the ubiquitiformal model and the experimental results are in closer agreement. Therefore, the introduction of scale invariance is crucial to the surface contact problem.
Tribological Performance of Polymer Composite Coatings Modified With La2O3 and MoS2 Nanoparticles
Authors: Zhang Dongya , Li Zhongwei , Gao Feng , Wei Xian , Ni Yuquan
Published: September 2019

In this study, composite coatings of polyvinylidene fluoride (PVDF) and epoxy resin deposited with La2O3 and MoS2 nanoparticles on the surface of a Babbitt alloy have been studied in order to improve its tribological performance. A pin-on-disc tribometer was used to evaluate the tribological properties of the Babbitt alloys with and without the composite coatings. The results showed that compared with the polymer-La2O3 composite coating, the polymer-MoS2 composite coating was more effective in reducing the friction coefficient and the wear rate of the Babbitt substrate under both dry and boundary lubrication conditions compared with the polymer-La2O3 composite coating. However, the wear rate of the Babbitt alloy with the polymer-La2O3 composite coating was lower than that of the alloy with the polymer-MoS2 composite coating. The wear scratches were analyzed using a scanning electron microscope (SEM). The worn surface of the polymer-La2O3 coating was much smoother and more continuous than that of the polymer-MoS2 coating, meanwhile transfer films were respectively detected on the pin surfaces. The addition of nanoparticles can reduce the wear rate and friction coefficient of polymer composite coating by forming a transfer film. Hence, the polymer composite coating can protect the Babbitt substrate.
Parametric Study and Improvement of Phase Separation in Intermediate Headers of Microchannel Condensers
Authors: Li Jun , Hrnjak Pega
Published: September 2019

Phase separation has been proven to be beneficial to air-cooled parallel flow microchannel condensers for air conditioning systems. The inlet to the condenser with phase separation is at the middle of the condenser height. After the first pass, in the vertical second header of the condenser, refrigerant vapor separates from liquid mainly due to gravitational effects. In ideal case, vapor should go to the top exit and liquid to the bottom exit, resulting in increased heat transfer. Due to interaction between vapor and liquid, separation is not perfect, expressed through the separation efficiency. This paper presents a parametric study of phase separation efficiency in the intermediate headers, with the target to improve separation efficiency. Header prototypes which have two exits are made with transparent polyvinyl chloride (PVC) to simulate the real header and provide visual access. Using R-134a as a baseline, the measurement of separation efficiency and its general trend will be shown first. The experimental results are compared to the simulation of a mechanistic model based on flow regime and force balance analysis. Inlet mass flux in simulation is controlled at 87–311 kg · m−2 · s−1 and inlet quality at 0.05–0.25. The observed flow patterns in header are compared with the modeling results. Then, the header diameter is increased, which effectively improves the separation efficiency due to reduction of vapor velocity in header. Finally, R245fa and R32 are modeled in comparison with R-134a to discuss the effect of fluid properties on separation efficiency.
A Dynamic Escape Problem of Molecular Motors
Authors: Culver Dean , Glaz Bryan , Stanton Samuel
Published: September 2019

Animal skeletal muscle exhibits very interesting behavior at near-stall forces (when the muscle is loaded so strongly that it can barely contract). Near this physical limit, the myosin II proteins may be unable to reach advantageous actin binding sites through simple attractive forces. It has been shown that the advantageous utilization of thermal agitation is a likely source for an increased force-production capacity and reach in myosin-V (a processing motor protein), and here we explore the dynamics of a molecular motor without hand-over-hand motion including Brownian motion to show how local elastic energy well boundaries may be overcome. We revisit a spatially two-dimensional mechanical model to illustrate how thermal agitation can be harvested for useful mechanical work in molecular machinery inspired by this biomechanical phenomenon without rate functions or empirically inspired spatial potential functions. Additionally, the model accommodates variable lattice spacing, and it paves the way for a full three-dimensional model of cross-bridge interactions where myosin II may be azimuthally misaligned with actin binding sites. With potential energy sources based entirely on realizable components, this model lends itself to the design of artificial, molecular-scale motors.
Vibration Control of Automotive Drive System With Nonlinear Gear Backlash
Authors: Yonezawa Heisei , Kajiwara Itsuro , Sato Shota , Nishidome Chiaki , Sakata Masato , Hatano Takashi , Hiramatsu Shigeki
Published: September 2019

In automotive drive systems, differential gear backlash degrades the control performance. Specifically, a shock torque, which is generated when the gear runs freely and collides with the backlash, increases the vibration amplitude. Consequently, it is important to develop a vibration control method to suppress the adverse effect of nonlinearity due to backlash. Furthermore, considering implementations on actual vehicles, design at the development site, and mass production, a simple and practical control method is necessary. This paper describes the configuration of a basic experimental device, which abstracts an actual vehicle to focus on the influence due to backlash while reflecting the basic structure of an automotive drive system. Next, a basic controller is designed using a mixed H2/H∞ control theory, and a servo system is constructed to track the target value. A simple control mode switching algorithm is proposed for backlash compensation. This algorithm is suited to practical applications because it uses only an output without a state estimation and it compensates for performance deteriorations due to the nonlinearity by operating a single linear controller. Finally, simulations and experiments verify the effectiveness of the proposed control system.
Motion Equations for the Ball and Beam and the Ball and Arc Systems
Authors: Lare Constance , White Warren N. , Hossain Sanzida
Published: September 2019

Presently, most derivations of the equations of motion for the ball and beam and ball and arc systems model the ball as a point mass. Other derivations apply assumptions related to the ball that lack physical justification. To understand fully the impact the ball has on the equations of motion and controller design, equations of motion are needed that stem from a derivation invoking few assumptions. At that point, simplifying assumptions applied in a consistent manner are possible. This paper derives the equations of motion for each mechanical system using fewer assumptions than what appears in the literature. The development then applies the assumptions needed to convert the derived dynamics to the well-used equations of motion seen in the literature. The presentation shows that some ball and beam models appearing in the literature do not stem from consistent assumptions or correct kinematics. Incorrect kinematics are also present in some of the ball and arc dynamic models. This paper also introduces dimensionless quantities to the dynamic equations of both systems rendering them in dimensionless form. Such formulations allow for comparisons between different systems through the size of the dimensionless quantities. The dimensionless systems are the means used to demonstrate that the equations of motion of each system are the same as the radius of the arc grows without bound. Finally, the paper shows that comparisons between different ball and beam models using these dimensionless numbers are now possible.
Hierarchical Control for Trajectory Generation and Tracking Via Active Front Steering
Authors: Hellewell Joseph S. , Popov Atanas A. , Burnett Gary E.
Published: September 2019

A new hierarchical model predictive controller (HMPC) for autonomous vehicle steering control is presented. The controller generates a path of shortest distance by determining lateral coordinates on a longitudinal grid, while respecting road bounds. This path is then parameterized by arc length before being optimized to restrict the normal acceleration values along the trajectory's arc length. The optimized trajectory is then tracked using a nonlinear MPC scheme using a bicycle plant model to calculate an optimal steering angle for the tires. The proposed controller is evaluated in simulation during a double-lane-change maneuver, where it generates and tracks a reference trajectory while observing the road boundaries and acceleration limits. Its performance is compared to a controller without path optimization, along with another that uses a smooth, predetermined, reference path instead of creating its own initial reference. It is shown that the proposed controller improves the tracking compared to a controller without path optimization, with a four-times reduction in average lateral tracking error. The average lateral acceleration is also reduced by 6%. The controller also maintains the tracking performance of a controller that uses a smooth reference path, while showing a much greater flexibility due to its ability to create its own initial reference path rather than having to follow a predetermined trajectory.
Warpage Characterization of Molded Wafer for Fan-Out Wafer-Level Packaging
Authors: Cheng Hsien-Chie , Liu Yan-Cheng
Published: September 2019

This study presents a comprehensive assessment of the process-induced warpage of molded wafer for chip-first, face-down fan-out wafer-level packaging (FOWLP) during the fan-out fabrication process. A process-dependent simulation methodology is introduced, which integrates nonlinear finite element (FE) analysis and element death-birth technique. The effects of the cure-dependent volumetric shrinkage, geometric nonlinearity, and gravity loading on the process-induced warpage are examined. The study starts from experimental characterization of the temperature-dependent material properties of the applied liquid type epoxy molding compound (EMC) system through dynamic mechanical analysis (DMA) and thermal mechanical analysis. Furthermore, its cure state (heat of reaction and degree of cure (DOC)) during the compression molding process (CMP) is measured by differential scanning calorimetry (DSC) tests. Besides, the cure dependent-volumetric (chemical) shrinkages of the EMC system after the in-mold cure (IMC) and postmold cure (PMC) are experimentally determined by which the volumetric shrinkage at the gelation point is predicted through a linear extrapolation approach. To demonstrate the effectiveness of the proposed theoretical model, the prediction results are compared against the inline warpage measurement data. One possible cause of the asymmetric/nonaxisymmetric warpage is also addressed. Finally, the influences of some geometric dimensions on the warpage of the molded wafer are identified through parametric analysis.
Cavitation Performance of Constant and Variable Pitch Helical Inducers for Centrifugal Pumps: Effect of Inducer Tip Clearance
Authors: Karakas Enver S. , Watanabe Hiroyoshi , Aureli Matteo , Evrensel Cahit A.
Published: September 2019

In this paper, the effect of the inducer tip clearance is studied to understand its impact on the cavitating and noncavitating performance of centrifugal pumps. Helical inducers with constant pitch and with variable (progressive) pitch are considered. Computational fluid dynamics (CFD) simulations of a single stage pump are conducted on each inducer type to determine the cavitating (two-phase) and noncavitating (single-phase) performance for varying inducer tip clearance. The Rayleigh–Plesset cavitation model is used to understand the bubble dynamics under the assumptions of single fluid undergoing no thermal energy transfer between each phase. Experimental tests are conducted on a pump with the variable pitch inducer to determine the true performance in cavitating and noncavitating operating conditions. Experimental results are compared to the simulations to validate the accuracy of the proposed numerical modeling. Net positive suction head (NPSH) with 3% differential head drop is used as a criterion to identify the true cavitation performance of each inducer configuration. It is found that, as the inducer tip clearance increases, excessive back leakage and larger vortex recirculation occur at the tip location. This results in pressure loss within the inducer and, consequently, degrades the cavitation performance. In addition, the change in cavitation performance with the tip clearance is much more evident for variable pitch inducer geometries as compared to the constant pitch case. Furthermore, the impact on the noncavitating performance of inducer tip clearance is found to be minimal.
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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Acquisition of
mcr-1
and Cocarriage of Virulence Genes in Avian Pathogenic Escherichia coli Isolates from Municipal Wastewater Influents in Japan
Authors: Hayashi Wataru , Tanaka Hayato , Taniguchi Yui , Iimura Masaki , Soga Eiji , Kubo Ryoichi , Matsuo Nao , Kawamura Kumiko , Arakawa Yoshichika , Nagano Yukiko , Nagano Noriyuki
Published: September 2019

Colistin is considered a last-line therapeutic option in severe infections due to multidrug-resistant Gram-negative bacteria, in particular carbapenemase-producing
Enterobacteriaceae
and multidrug-resistant
Acinetobacter baumannii
. An increasing prevalence of
mcr
genes in diverse
Enterobacteriaceae
species, mainly
Escherichia coli
and
Klebsiella pneumoniae
from humans and food animals, has become a significant concern to public health all over the world. In Japan,
mcr
genes have so far been detected in food animals, raw meat, wastewater, and human clinical samples. This study reports the copresence of
mcr-1
and avian pathogenic
E. coli
(APEC)-associated virulence genes in five of seven
E. coli
isolates recovered from aquatic environments in Japan. Our study highlights the importance and urgency of action to reduce environmental contamination by
mcr
genes that may likely occur due to exposure to untreated wastewater through combined sewer overflow by recent unusual weather.
Coxiella burnetii Intratracheal Aerosol Infection Model in Mice, Guinea Pigs, and Nonhuman Primates
Authors: Gregory A. E. , van Schaik E. J. , Russell-Lodrigue K. E. , Fratzke A. P. , Samuel J. E.
Published: September 2019

Coxiella burnetii, the etiological agent of Q fever, is a Gram-negative bacterium transmitted to humans by inhalation of contaminated aerosols. Acute Q fever is often self-limiting, presenting as a febrile illness that can result in atypical pneumonia. In some cases, Q fever becomes chronic, leading to endocarditis that can be life threatening. The formalin-inactivated whole-cell vaccine (WCV) confers long-term protection but has significant side effects when administered to presensitized individuals.
Elucidation of the Interleukin 12 Production Mechanism during Intracellular Bacterial Infection in Amberjack,Seriola dumerili
Authors: Matsumoto Megumi , Kubota Taisei , Fujita Sinsuke , Shiozaki Kazuhiro , Kishida Shosei , Yamamoto Atsushi
Published: September 2019

Intracellular bacterial infections affect all vertebrates. Cultured fish are particularly vulnerable because no effective protection measures have been established since such infections emerged approximately 50 years ago. As in other vertebrates, the induction of cell-mediated immunity (CMI) plays an important role in protecting fish against infection. However, details of the mechanism of CMI induction in fish have not been clarified.
Development of Transposon Mutagenesis for Chlamydia muridarum
Authors: Wang Yibing , LaBrie Scott D. , Carrell Steven J. , Suchland Robert J. , Dimond Zoe E. , Kwong Forrest , Rockey Daniel D. , Hefty P. Scott , Hybiske Kevin
Published: September 2019

Historical issues with genetic manipulation of
Chlamydia
have prevented rigorous functional genetic characterization of the ∼1,000 genes in chlamydial genomes. Here, we report the development of a transposon mutagenesis system for
C. muridarum
, a mouse-adapted
Chlamydia
species that is widely used for
in vivo
investigations of chlamydial pathogenesis. This advance builds on the pioneering development of this system for
C. trachomatis
. We demonstrate the generation of an initial library of 33 mutants containing stable single or double transposon insertions. Using these mutant clones, we characterized
in vitro
phenotypes associated with genetic disruptions in glycogen biosynthesis and three polymorphic outer membrane proteins.