bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Forced Convective Heat Transfer of FC-72 in Vertical Small Tubes
Authors: Li Yantao , Ji Yulong , Fukuda Katsuya , Liu Qiusheng
Published: May 2020

This paper presents an experimental investigation of the forced convective heat transfer of FC-72 in vertical tubes at various velocities, inlet temperatures, and tube sizes. Exponentially escalating heat inputs were supplied to the small tubes with inner diameters of 1, 1.8, and 2.8 mm and effective heated lengths between 30.1 and 50.2 mm. The exponential periods of heat input range from 6.4 to 15.5 s. The experimental data suggest that the convective heat transfer coefficients increase with an increase in flow velocity and µ/µw (refers to the viscosity evaluated at the bulk liquid temperature over the liquid viscosity estimated at the tube inner surface temperature). When tube diameter and the ratio of effective heated length to inner diameter decrease, the convective heat transfer coefficients increase as well. The experimental data were nondimensionalized to explore the effect of Reynolds number (Re) on forced convection heat transfer coefficient. It was found that the Nusselt numbers (Nu) are influenced by the Re for d = 2.8 mm in the same pattern as the conventional correlations. However, the dependences of Nu on Re for d = 1 and 1.8 mm show different trends. It means that the conventional heat transfer correlations are inadequate to predict the forced convective heat transfer in minichannels. The experimental data for tubes with diameters of 1, 1.8, and 2.8 mm were well correlated separately. And, the data agree with the proposed correlations within ±15%.
Microstructural Stress Shape Optimization Using the Level Set Method
Authors: Picelli Renato , Townsend Scott , Alicia Kim H.
Published: May 2020

This paper applies stress-based shape optimization to microstructures, a scarcely explored topic in the literature. As the actual stresses arising at the macroscopic structure are scale separated, the microstrucural stress is considered herein as the state of a representative volume element (RVE) after applying test unit strain load cases, not related to the macroscale loads. The three stress states in 2D are aggregated via p-norm functions, which are used for stress minimization. A stress-based level set method is applied. The method linearizes the objective and constraint functions and solves an optimization problem at every iteration to obtain the boundary velocities. The Ersatz material approach is used to compute the stiffness of the elements sliced by the boundary. A single hole inclusion microstructure is optimized for minimum stress in order to verify the methodology.
Agent-Based Modeling of Decisions and Developer Actions in Wind Farm Landowner Contract Acceptance
Authors: Syal Sita M. , Ding Yiqing , MacDonald Erin F.
Published: May 2020

This paper presents an agent-based model to investigate interactions between wind farm developers and landowners. Wind farms require hundreds of square miles of land for development and developers typically interact with landowners to lease land for construction and operations. Landowners sign land lease contracts without knowing the turbine layout, which affects aesthetics of property as well as value of the lease contract. Having a turbine placed on one's land is much more lucrative than alternative land uses, but landowners must sign over the use of their land without knowing whether they will receive this financial benefit or not. This process, typically referred to as “Landowner Acquisition,” is highly uncertain for both stakeholders—a source stated up to 50% of wind projects fail due to landowner acquisition issues. We present an agent-based model to study the landowner acquisition period with unique decision-making characteristics for nine landowners and a developer. Citizen participation is crucial to the acceptance of wind farms; thus, we use past studies to quantify three actions a developer can take to influence landowners: (1) community engagement meetings, (2) preliminary environmental studies, and (3) sharing the wind turbine layout with the landowner. Results show how landowner acceptance rates can change over time based on what actions the developer takes. While still in the “proof of concept” stage, this model provides a framework for quantifying wind stakeholder interactions and potential developer actions. Suggestions for how to validate the framework in the future are included in the discussion.
A Novel Ortho-Triplex Tensegrity Derived by the Linkage-Truss Transformation With Prestress-Stability Analysis Using Screw Theory
Authors: Wu Liheng , Dai Jian S.
Published: May 2020

This paper presents a novel tensegrity structure derived from the tensegrity triplex (also called the simplex or regular triangular prism) by using the linkage-truss transformation. In this paper, the tensegrity triplex is first transformed into a 6R linkage with vertical members as revolute joints and is coined the triplex linkage. With this, a novel 6R linkage was derived, whose joint axes are perpendicular to the joint axes of the triplex linkage and is coined the ortho-triplex linkage. Rigidity analysis based on screw theory demonstrates that both obtained linkages with infinitesimal mobility are prestress stable. Finally, transforming the ortho-triplex linkage to a truss, by using cables for tensional members and struts for compressional members, leads to a novel tensegrity that is coined ortho-triplex tensegrity. A non-dimensional quadratic form is further provided to analyze the sensitivity of prestress-stability in terms of the structural parameters. The process of derivation of this novel tensegrity presents a new way of designing tensegrity structures with prestress-stability analysis based on screw theory.
An Efficient Batch K-Fold Cross-Validation Voronoi Adaptive Sampling Technique for Global Surrogate Modeling
Authors: Kaminsky Andrew L. , Wang Yi , Pant Kapil
Published: May 2020

Surrogate models can be used to approximate complex systems at a reduced cost and are widely used when data generation is expensive or time consuming. The accuracy of these models is dependent on the samples used to create them. Therefore, proper sample selection within the parameter space is paramount. Numerous design of experiments (DOE) methodologies have been developed with the aim of identifying the optimal sample set to capture the system of interest. Adaptive sampling techniques are a subclass of DOE methods that identify optimal locations for new samples by leveraging response information from existing samples. By exploiting knowledge of the system, adaptive sampling methods have been demonstrated to significantly reduce the number of samples required to build a surrogate model of a given accuracy. However, utilizing the response information of the previous samples adds a computational cost associated with determining the ideal sample locations. Additionally, this cost typically grows with the sample count. This article presents techniques to reduce the cost associated with the adaptive sampling procedure so that the cost savings provided by adaptive sampling are maximized. A new K-fold cross-validation (KFCV)-Voronoi adaptive sampling technique is proposed to reduce the sample selection costs by adding a global KFCV filter to the cross-validation (CV)-Voronoi technique. The costs are further reduced through an innovative Voronoi batch sampling technique that is demonstrated to outperform naïve batch sampling. The proposed adaptive sampling acceleration techniques are evaluated using benchmark functions of increasing dimension and aerodynamic loading data.
A Novel Variable Stiffness Compliant Robotic Gripper Based on Layer Jamming
Authors: Gao Yuan , Huang Xiguang , Mann Ishan Singh , Su Hai-Jun
Published: May 2020

In this paper, we present a novel compliant robotic gripper with three variable stiffness fingers. While the shape morphing of the fingers is cable-driven, the stiffness variation is enabled by layer jamming. The inherent flexibility makes compliant gripper suitable for tasks such as grasping soft and irregular objects. However, their relatively low load capacity due to intrinsic compliance limits their applications. Variable stiffness robotic grippers have the potential to address this challenge as their stiffness can be tuned on demand of tasks. In our design, the compliant backbone of finger is made of 3D-printed PLA materials sandwiched between thin film materials. The workflow of the robotic gripper follows two basic steps. First, the compliant skeleton is driven by a servo motor via a tension cable and bend to a desired shape. Second, upon application of a negative pressure, the finger is stiffened up because friction between contact surfaces of layers that prevents their relative movement increases. As a result, their load capacity will be increased proportionally. Tests for stiffness of individual finger and load capacity of the robotic gripper are conducted to validate capability of the design. The results showed a 180-fold increase in stiffness of individual finger and a 30-fold increase in gripper’s load capacity.
Workspace Augmentation for the Large-Scale Spherical Honeycombs Perfusion Using a Novel 5DOF Reconfigurable Manipulator
Authors: Yang Hui , Fang Hairong , Li Xiangyun , Fang Yuefa
Published: May 2020

The volume of workspace is a significant kinematic index of parallel manipulator in some applications of engineering. However, the workspace degradation of the manipulator in extreme position is a demanding issue, which results in a fact that such manipulators cannot satisfy the machining requirement of the maximum limit position for the large-scale complex structural components. In this paper, a novel five degrees-of-freedom (DOF) 5PRR+5PUS-PRPU parallel manipulator (PM) is presented. First, the mobility analysis for the proposed manipulator is carried out, and the inverse kinematics as well as the Jacobian matrix is developed. Then, the workspace of the 5PRR+5PUS-PRPU PM and the 5PUS-PRPU PM is analyzed to study the workspace augmentation of the proposed PM. The workspace comparisons of these two PMs prove that the proposed PM not only can realize the large movement of the moving platform along the z-axis, but also possess larger workspace than the 5PUS-PRPU PM when the moving platform has a large movement along the z-axis. Furthermore, the singularity analysis is also conducted to show the singularity-free workspace of the proposed PM. By the introduction of the reconfigurable 5PRR PM, the proposed manipulator effectively augments the reachable workspace of the moving platform along the z-axis and to some extent also solves the issue of workspace degradation of the PM along z-axis.
One-Dimensional Zonal Model for the Unsteady Heat Transfer Analysis in an Open Volumetric Air Receiver
Authors: Singh Gurveer , Kumar Vishwa Deepak , Chandra Laltu , Shekhar R. , Ghoshdastidar P. S.
Published: May 2020

The open volumetric air receiver (OVAR)-based central solar thermal systems provide air at a temperature > 1000 K. Such a receiver is comprised of porous absorbers, which are exposed to a high heat-flux > 800 Suns (1 Sun = 1 kW/m2). A reliable assessment of heat transfer in an OVAR is necessary to operate such a receiver under transient conditions. Based on a literature review, the need for developing a comprehensive, unsteady, heat transfer model is realized. In this paper, a seven-equations based, one-dimensional, zonal model is deduced. This includes heat transfer in porous absorber, primary-air, return-air, receiver casing, and their detailed interaction. The zonal model is validated with an inhouse experiment showing its predictive capability, for unsteady and steady conditions, within the reported uncertainty of ±7%. The validated model is used for investigating the effect of operating conditions and absorber geometry on the thermal performance of an absorber. Some of the salient observations are (a) the maximum absorber porosity of 70–90% may be preferred for non-volumetric and volumetric-heating conditions, (b) the minimum air-return ratio should be 0.7, and (c) the smallest gap to absorber-length ratio of 0.2 should suffice. Finally, suggestions are provided for extending the model.
Solution of Unsteady Fluid Dynamic and Energy Equations for High-Speed Oscillating Compressible Flows and Blast Wave Propagations
Authors: Sinha Ramlala P.
Published: May 2020

A solution of the highly complex unsteady high-speed oscillating compressible flow field inside a cylindrical tube has been obtained numerically, assuming one-dimensional, viscous, and heat conducting flow, by solving the appropriate fluid dynamic and energy equations. The tube is approximated by a right circular cylinder closed at one end with a piston oscillating at very high resonant frequency at the other end. An iterative implicit finite difference scheme is employed to obtain the solution. The scheme permits arbitrary boundary conditions at the piston and the end wall and allows assumptions for transport properties. The solution would also be valid for tapered tubes if the variations in the cross-sectional area are small. In successfully predicting the time-dependent results, an innovative simple but stable solution of unsteady fluid dynamic and energy equations is provided here for wide-ranging research, design, development, analysis, and industrial applications in solving a variety of complex fluid flow heat transfer problems. The method is directly applicable to pulsed or pulsating flow and wave motion thermal energy transport, fluid–structure interaction heat transfer enhancement, and fluidic pyrotechnic initiation devices. It can further be easily extended to cover muzzle blasts and nuclear explosion blast wave propagations in one-dimensional and/or radial spherical coordinates with or without including energy generation/addition terms.
Co-Axial Laminar Multiphase Jet: A Novel Methodology for the Attainment Enhancement in Transition Boiling Regime
Authors: Barik Kashinath , Swain B. , Pati A.R. , Chitransh Susmit , Mohapatra S.S.
Published: May 2020

In the current investigation, by using a very low mass flux co-axial laminar multiphase fluid jet, enhancement in heat transfer rate, uniformity in heat flux distribution, and reduction in coolant consumption rate characteristics are simultaneously tried to achieve in case of cooling from a very high initial temperature (900 °C). The information on quenching technology depicting all the above-mentioned advantages has not been reported in the literature. In the present work, kerosene–water, nanofluid (Al2O3 = 0.15%)–kerosene, and nanofluid (Al2O3 = 0.15%)–polyethylene glycol combinations were used for co-axial cooling experimentation. From the heat transfer analysis, it is observed that nanofluid (Al2O3 = 0.15%) and kerosene combination produces maximum critical heat flux due to the alteration of thermophysical and interfacial properties, which enhance the driving force and flow behavior defining momentum and thermal diffusivities in the favorable direction of heat transfer, respectively. In addition to the above, the comparative study ensures a significant reduction in coolant consumption and augmentation in uniformity in heat flux distribution.
Development and Validation of a Model for Efficient Simulation of Freezing of Water in Large Tanks
Authors: Ramesh Vishal , Terala Shashank , Mazumder Sandip , Matharu Gurpreet , Vaishnav Dhaval , Ali Syed
Published: May 2020

Liquid water–urea mixtures are used in diesel vehicles for exhaust after treatment. In cold weather, the entire liquid may freeze and the process may span over a day. Traditional computational fluid dynamics and heat transfer (CFD/CHT) methodologies are impractical for modeling such freezing processes because of restrictions in the time-step size—typically milliseconds—posed by numerical stability and physical timescale considerations. Preliminary investigations revealed that the primary constraint for using small time-steps is the fine-scale motion generated by natural convection in both the liquid and the gas. A new model is proposed and demonstrated for efficient prediction of the propagation of the solidification front. In this model, heat transfer due to natural convection is modeled as a diffusive process analogous to how turbulent transport is modeled using an eddy diffusivity. The model enables the use of large time-steps since the fine-scale motions due to natural convection are not resolved. It was validated against experimental data for pure water, which were also collected as part of the study. Each experiment collected data at intervals of 6 s for a total duration of about 24 h. Several different tank fill levels were considered, and a good agreement with experimental data was noted, especially for shallow fill levels. Large-scale parallel three-dimensional calculations were conducted for the freezing of pure water in a few days of computational time as opposed to a year (projected) of computational time using traditional CFD/CHT models and the same computational resources.
Thermodynamic Analysis of Hydrogen Production From Coal Char Gasification in Triple-Bed Circulating Fluidized Bed
Authors: Xiang Xianan , Gong Guangcai , Wang Chenhua , Cai Ninghua , Tang Kun , Li Yongsuo
Published: May 2020

The triple-bed circulating fluidized bed gasifier is a new type of the gasification process in which the combustion process, pyrolysis process, and gasification process of the fuel are carried out in different reactors. The inert heat carrier is used to transfer heat between the reactors. In this way, the gasification efficiency of char is improved since the tar and pyrolysis gas generated in the pyrolysis process will no longer hinder the gasification of the char. The thermodynamic equilibrium model is used to simulate the gasification process of the triple-bed circulating fluidized bed, and the sub-models are established to simulate combustion, pyrolysis, and gasification processes. The simulation results agree well with the experimental values. Besides, the model studies the effects of key parameters such as the gasification reaction temperature and the ratio of steam to C (S/C) on gasification performance. Results showed that higher gasification reaction temperature has a positive effect on gasification performance, S/C may not be too high, and excessive water vapor will directly affect the gasification reaction.
Transient Temperature Distribution and Thermo-Mechanical Coupling Response of Paper in the Fusing Process of Laser Printers
Authors: Liu Pingping , Zhang Huijie , Wen Guang , Zuo Fangjun , Jia Meiwei
Published: May 2020

The hot-press fusing process of a laser printer is one of the principal causes for paper folding and bending deformation. In order to predict and control the deformation of paper, first, the following analysis method is proposed for the transient temperature field analysis of the continuous moving paper: discretizing the thermal analysis process, replacing the moving paper model with the moving heat source, and simulating the movement speed of paper by setting the flow boundary conditions. Second, taking the steady-state thermal calculation results of the printer in the standby mode as initial conditions, the temperature distribution characteristics of paper during the movement are obtained with the paper model placed in a whole-machine environment to analyze the transient temperature field. Third, using the method of multi-field coupling, the transient temperature field results of paper are taken as the external load of its static analysis to analyze the deformation of paper during the fusing process; therefore, the quantitative deformation results and deformation characteristics of paper after fusing are obtained. According to the results, more precise boundary conditions can be achieved by calculating the temperature field of paper in a whole-machine environment. The method of transient temperature field analysis for continuous moving objects proposed in this study can effectively simulate the movement process of paper. The results reveal the mechanism of paper wrinkle and bending deformation in the fusing process, which can be used to predict the conveying performance of paper and guide the design work of the printer.
Study of the Comprehensive Evaluation of Energy Efficiency of an Oilfield Heating Furnace Based on Combination Weighting Method
Authors: Cheng Qinglin , Wang Ronghuan , Sun Wei , Meng Lan , Gao Wei , Li Yuchun
Published: May 2020

The heating furnace is an essential oilfield facility for surface gathering, treatment, and transportation, so the energy consumption level of an oilfield is directly affected by its operational efficiency. In this paper, the thermal efficiency, exhaust gas temperature, external surface temperature, excess air coefficient, and load rate of a heating furnace are taken as energy efficiency evaluation indexes. By improving game theory, the objective and subjective weights are combined to determine the final weights of each index. On this basis, the grey TOPSIS method is used to establish the energy efficiency evaluation model of an oilfield heating furnace, which is to comprehensively evaluate the energy consumption of the heating furnace by calculating the closeness degree between its actual and ideal operational states. Finally, the effectiveness of the energy efficiency evaluation model is verified by taking an actual oilfield as an example, the results show that the weight sequence of the indexes is thermal efficiency, exhaust gas temperature, external surface temperature, load rate, and excess air coefficient. In addition, the relative closeness of the heating furnace is mostly concentrated between 0.5 and 0.7, which shows that the efficiency is low. The weak link of energy consumption is analyzed, and the corresponding improvement measures are put forward.
Numerical Analysis of Heat Transfer Enhancement in a Micro-Channel Due to Mechanical Stirrers
Authors: Sreejith M. , Chetan S. , Khaderi S. N.
Published: May 2020

Using two-dimensional numerical simulations of the momentum, mass, and energy conservation equations, we investigate the enhancement of heat transfer in a rectangular micro-fluidic channel. The fluid inside the channel is assumed to be stationary initially and actuated by the motion imparted by mechanical stirrers, which are attached to the bottom of the channel. Based on the direction of the oscillation of the stirrers, the boundary conditions can be classified as either no-slip (when the oscillation is perpendicular to the length of the channel) or periodic (when the oscillation is along the length of the channel). The heat transfer enhancement due to the motion of the stirrers (with respect to the stationary stirrer situation) is analyzed in terms of the Reynolds number (ranging from 0.7 to 1000) and the Peclet number (ranging from 10 to 100). We find that the heat transfer first increases and then decreases with an increase in the Reynolds number for any given Peclet number. The heat transferred is maximum at a Reynolds number of 20 for the no-slip case and at a Reynolds number of 40 for the periodic case. For a given Peclet and Reynolds number, the heat flux for the periodic case is always larger than the no-slip case. We explain the reason for these trends using time-averaged flow velocity profiles induced by the oscillation of the mechanical stirrers.
Thermodynamic Analysis for Supercritical Carbon Dioxide Brayton Cycle by Considering Both Thermal Efficiency and Cooler Area
Authors: Hu Peng , Jiang Yi-Ran , Zhang Gao-Wei , Miao Zhen
Published: May 2020

The performances of the supercritical carbon dioxide (sCO2) Brayton cycle with the recuperator were investigated by the simulation method. Evaluation criteria were proposed for system performance optimization. The calculation and analysis of the system thermal efficiency and the length of the cooler were performed. The effects of the inlet and outlet pressure of the expander, the heat transfer coefficient and the logarithmic mean temperature difference (LMTD) on the system thermal efficiency and the length of the cooler were investigated. The system thermal efficiency has a peak value with the increase of the expander inlet pressure. The peak value varies from 45% to 45.4% with different expander outlet pressures. The average heat transfer coefficient and the length of the cooler decrease with the increase of the inlet pressure, but the LMTD is on the contrary. When the expander inlet pressure is in the low-pressure stage (22–26 MPa), the thermal efficiency of the lower outlet pressure (8 MPa) is higher, which ranges from 44.3% to 45.4%. However, the length of the cooler is also larger (6.7–10.9 m). As the expander inlet pressure rises to the high-pressure stage (26–30 MPa), the higher outlet pressure (9.5 MPa) has a greater advantage in the thermal efficiency, and the range of efficiency is 44.7–45%. Similarly, the length of the cooler is the largest (4.5–8 m). Therefore, both the thermal efficiency and the length of the cooler should be fully considered in the design of the system operating conditions.
Experimental Investigation of Air-Source Heat Pump Heating System With a Novel Thermal Storage Refrigerant-Heated Panel
Authors: Shao Suola , Zhang Huan , You Shijun , Wang Yaran
Published: May 2020

In response to the triple crisis of energy–environment–economy (3Es), the air-source heat pump (ASHP) system is considered to be one of the most feasible candidates to upgrade the traditional high emission heating solutions. In this paper, a novel thermal storage refrigerant-heated panel (RHP) is proposed for the ASHP heating system. Experiments were conducted in a climate chamber to test the heating and defrosting performance of the system, the thermal performance of the RHP, the system energy efficiency, and the system economic feasibility. The results show that the heat flux of the RHP is as high as 625.5 W/m2 at a condensation temperature of 40 °C and an outdoor air temperature of −7 °C. Meanwhile, the system is demonstrated to be reliable and competitive with efficient thermal stability in heating conditions and comfortable indoor thermal in defrosting conditions. The coefficient of performance (COP) ranges from 2.2 to 4.0 when the outdoor air temperature changes from −12 °C to 7 °C in the tests. Meanwhile, the initial capital cost and the total annual cost of the proposed system are 430 USD and 203.1 USD, respectively, which is competitive in the distracted heating systems.
Physics-Informed Neural Networks for Missing Physics Estimation in Cumulative Damage Models: A Case Study in Corrosion Fatigue
Authors: Dourado Arinan , Viana Felipe A. C.
Published: May 2020

We present a physics-informed neural network modeling approach for missing physics estimation in cumulative damage models. This hybrid approach is designed to merge physics-informed and data-driven layers within deep neural networks. The result is a cumulative damage model in which physics-informed layers are used to model relatively well understood phenomena and data-driven layers account for hard-to-model physics. A numerical experiment is used to present the main features of the proposed framework. The test problem consists of predicting corrosion-fatigue of an Al 2024-T3 alloy used on panels of aircraft wings. Besides cyclic loading, panels are also subjected to saline corrosion. In this case, physics-informed layers implement the well-known Walker model for crack propagation, while data-driven layers are trained to compensate the bias in damage accumulation due to the corrosion effects. The physics-informed neural network is trained using full observation of inputs (far-field loads, stress ratio, and a corrosivity index defined per airport) and very limited observation of outputs (crack length at inspection for only a small portion of the fleet). Results show that the physics-informed neural network is able to learn how to compensate the missing physics of corrosion in the original fatigue model. Predictions from the hybrid model can be used in fleet management, for example, to prioritize inspection across the fleet or forecast ahead of time the number of planes with damage above a threshold.
A General Modeling Methodology for the Quasistatic Behavior of Spiral Torsion Springs
Authors: Munoz-Guijosa Juan M. , Silva Alejandro , Alén-Cordero Cristina , Guzmán Álvaro
Published: May 2020

Due to their robustness, compactness, simplicity, and the possibility of nonlinear torque curves, spiral springs are being increasingly contemplated for industrial application. Recent manufacturing technologies and materials allow for the creation of spiral springs of various shapes and geometries able to provide the required torque curves. Modeling the behavior of this kind of springs is highly complex due to the strong nonlinearities arisen from large deflections and the possibility of coiling of strip length around the spring barrel or arbor. For this reason, up to our knowledge, existing models only provide design features such as deflection and torque curve for the simplest strip geometries, and fewer models supply, only if no strip coiling occurs, reactions at the strip-barrel and strip-arbor clampings. In addition, to our knowledge, just semi-empirical models for strip-barrel, -arbor and -strip contact forces or friction torques were available. In this work, we introduce a novel general, an analytical quasistatic model for the calculation of all the above spring characteristics for any length-dependent strip material and initial geometry and strip cross-sectional shape and for any barrel and arbor radii. The strip deflection curvatures are calculated minimizing the sum of elastic and gravitational potential energies under geometrical constraints associated with eventual strip coiling. Once the curvatures are calculated, the spring internal, contact, and reaction forces can be straightforwardly calculated by solving the elastica differential equations. Friction is taken into account by evaluating the contact conditions at the strip coiled sections.
Rotatability of the Floating Link on Multi-Loop Planar Linkages
Authors: Chan Cody Leeheng , Ting Kwun-Lon
Published: May 2020

This paper proposes a method to deal with the orientation uncertainty problem affected by joint clearances. To solve this problem, it is necessary to establish the theory of mobility of the floating link of multi-loop linkages. Since the theory of the mobility of floating link is yet complete, this paper provides a simple treatment to determine the rotatability between any two links, adjoined or not, in planar multi-loop linkages. The rotation angle of the floating link with respect to the reference link is defined so that there is no ambiguity in analyzing the rotation range of the floating link. Based on the joint rotation space (JRS) method, one may identify not only the branch formation but also the rotatability between any two links on each of the branches. It is a visualized method that reveals the rotation characteristic of multi-loop linkages. This paper demonstrates the rotation range of the floating link with respect to the reference link on six-bar Stephenson linkages, 2-degree-of-freedom (DOF). 7-bar linkages, and 3-DOF. Eight-bar parallel manipulators. This might be the first paper to deal with the rotatability of 3-DOF planar multi-loop linkages. This paper uses the method to predict the clearance-induced angle uncertainty of the 8-bar parallel manipulators, which determines the worst orientation error of the end-effector and fills up the void of the joint clearance uncertainty model proposed by Ting et al. (2017, “Clearance-Induced Position Uncertainty of Planar Linkages and Parallel Manipulators,” J. Mech. Rob., 9, p. 061001).
Forward Kinematic Analysis of Kinematically Redundant Hybrid Parallel Robots
Authors: Wen Kefei , Gosselin Clément M.
Published: May 2020

This paper focuses on the forward kinematic analysis of (6 + 3)-degree-of-freedom kinematically redundant hybrid parallel robots. Because all of the singularities are avoidable, the robot can cover a very large orientational workspace. The control of the robot requires the solution of the direct kinematic problem using the actuator encoder data as inputs. Seven different approaches of solving the forward kinematic problem based on different numbers of extra encoders are developed. It is revealed that five of these methods can produce a unique solution analytically or numerically. An example is given to validate the feasibility of these approaches. One of the provided approaches is applied to the real-time control of a prototype of the robot. It is also revealed that the proposed approaches can be applied to other kinematically redundant hybrid parallel robots proposed by the authors.
Physical Activity and Sport in Trans Persons Before and After Gender Disclosure: Prevalence, Frequency, and Type of Activities
Authors: López-Cañada Elena , Devís-Devís José , Valencia-Peris Alexandra , Pereira-García Sofía , Fuentes-Miguel Jorge , Pérez-Samaniego Víctor
Published: May 2020

Background: This study describes the prevalence, frequency, and type of physical activity and sport (PAS) practiced by trans persons before and after their gender disclosure (GD). Methods: A face-to-face survey was administered to 212 Spanish trans persons, aged from 10 to 62 years old. McNemar and chi-square tests were used to determine significant differences. Results: About 75.5% of the trans persons in this study engaged in PAS and more than 50% did so ≥3 times/week, which is similar as in the general Spanish population. Participation was higher in trans men (78.7%) than trans women (72%). However, GD emerges as a key issue in characterizing trans persons’ PAS participation. A group of 14.5% of them stopped activity after GD. Participation in nonorganized PAS was higher than in organized PAS, and this difference is greater after GD because most participants gave up organized PAS in favor of nonorganized PAS. Trans persons preferred individual sports and activities than team sports before and after GD, and the top 3 activities were jogging, walking, and bodybuilding. Trans men participation was higher than trans women in team PAS, whereas individual PAS were equally practiced before and after GD. Participation in football, swimming, basketball, dancing, and volleyball declined after GD, whereas bodybuilding increased in trans men. Conclusions: The results show that the high involvement of trans persons coincides with strategies used to hide or conceal their gender identities when participating in PAS. A decrease in PAS participation is observed after GD probably because it is an acute potential period of anxiety, discrimination, and victimization caused by trans persons’ body exposure.
ACTup: advanced communication training simulation enhanced by actors trained in the Stanislavski system
Authors: Sweeney Rory , McNaughten Ben , Thompson Andrew , Storey Lesley , Murphy Paul , Bourke Thomas
Published: May 2020

Strong communication, empathy and interpersonal skills are crucial to good clinical practice. Actors trained in interpretations of the Stanislavski system draw on their own life experience to develop the character. We hypothesised that simulation enhanced by trained actors would be an ideal way for our senior trainees to develop advanced communication skills. We developed a communication training course based on challenging situations which occur in paediatrics like child death and safeguarding. Actors were briefed and invited to develop characters that would behave and respond as a parent/carer might do in complex and stressful clinical scenario. Paediatric trainees then participated in simulations, with a focus on communication skills. Feedback and debrief were provided by a multidisciplinary faculty. The impact of the course was evaluated by analysis of data collected in focus groups held after the simulation. Trainees noted the actor’s ability to respond in vivo to emotive situations and felt it was much more effective than their previous experience of simulation with simulated patients without formal training. Actors were able to offer feedback on aspects of body language, tone and use of language from a non-medical perspective. Actors enhanced the realism of the simulations by changing their language and emotional performance in response to the trainee’s performance, improving trainee engagement.
Prevalence and associated phenotypes of DUSP6, IL17RD and SPRY4 variants in a large Chinese cohort with isolated hypogonadotropic hypogonadism
Authors: Men Meichao , Wang Xinying , Wu Jiayu , Zeng Wang , Jiang Fang , Zheng Ruizhi , Li Jia-Da
Published: May 2020

Background

FGF8-FGFR1 signalling is involved in multiple biological processes, while impairment of this signalling is one of the main reasons for isolated hypogonadotropic hypogonadism (IHH). Recently, several negative modulators of FGF8-FGFR1 signalling were also found to be involved in IHH, including DUSP6, IL17RD, SPRY2 and SPRY4. The aim of this study was to investigate the genotypic and phenotypic spectra of these genes in a large cohort of Chinese patients with IHH.

Methods

A total of 196 patients with IHH were enrolled in this study. Whole-exome sequencing was performed to identify variants, which was verified by PCR and Sanger sequencing.

Results

Four heterozygous DUSP6 variants (p.S157I, p.R83Q, p.P188L and p.N355I) were found in six patients. Cryptorchidism, dental agenesis, syndactyly and blue colour blindness were commonly observed in patients with DUSP6 mutations. Six heterozygous IL17RD variants (p.P191L, p.G35V, p.S671L, p.A221T, p.I329M and p.I329V) were found in seven patients. Segregation analysis indicated that 100% (5/5) of probands inherited the IL17RD variants from their unaffected parents, and oligogenicity was found in 4/7 patients. One rare SPRY4 variant (p.T68S) was found in a female patient with Kallmann syndrome who also carried a PLXNA1 mutation.

Conclusion

Our study greatly enriched the genotypic and phenotypic spectra of DUSP6, IL17RD and SPRY4 in IHH. Mutations in DUSP6 alone seem sufficient to cause IHH in an autosomal dominant manner, whereas IL17RD or SPRY4 mutations may cause IHH phenotypes in synergy with variants in other IHH-associated genes.
Molecular epidemiological analysis of
Mycoplasma genitalium
shows low prevalence of azithromycin resistance and a well-established epidemic in South Africa
Authors: Laumen Jolein G E , van Alphen Lieke B , Maduna Liteboho D , Hoffman Charlotte M , Klausner Jeffrey D , Medina-Marino Andrew , Kock Marleen M , Peters Remco P H
Published: May 2020

Objectives

Macrolide resistance in
Mycoplasma genitalium
is emerging globally. There is paucity of data from sub-Saharan Africa where syndromic management is used to treat sexually transmitted infections (STIs). We conducted a molecular epidemiological study to determine the prevalence of azithromycin resistance and epidemic diversity of
M. genitalium
infections in South Africa.

Methods

We analysed 90
M. genitalium
-positive specimens that had been collected consecutively from men and women (50% symptomatic) from geographically diverse communities across the northern part of South Africa between 2015 and 2019. Melting curve analysis followed by targeted sequencing of the 23S rRNA gene was performed to detect azithromycin resistance. Molecular typing was done through single nucleotide polymorphism (SNP) analysis of the MG191 gene and short tandem repeats (STR) assessment of the MG309 gene. An overview of all published
M. genitalium
sequence types was generated and novel sequence types identified in this study were allocated numbers accordingly.

Results

Azithromycin resistance was detected in 1/90
M. genitalium
-positive specimens (1.1%; 95% CI 0% to 3.3%) as conferred by A2071G mutation; this strain also harboured a C234T mutation in the
parC
gene with wild type
gyrA
gene. SNP typing and STR assessment was successful in 38/90 specimens (42%) and showed a genetically diverse epidemic, without geographic clustering, with eight novel sequence types identified.

Conclusion

This is the first study that determines resistance in
M. genitalium
infection since introduction of azithromycin in the syndromic management regimen for STIs in South Africa in 2015. Despite a well-established epidemic, azithromycin-resistant
M. genitalium
infection is still uncommon in the public healthcare sector. However, it has the potential to undermine the effectiveness of syndromic management. Introduction of molecular diagnostics and continuous surveillance are warranted for early detection emergence of resistance.
Tablet and web-based audiometry to screen for hearing loss in adults with cystic fibrosis
Authors: Vijayasingam Anitha , Frost Emily , Wilkins Julie , Gillen Lise , Premachandra Presanna , Mclaren Kate , Gilmartin Desmond , Picinali Lorenzo , Vidal-Diez Alberto , Borsci Simone , Ni Melody Zhifang , Tang Wai Y , Morris-Rosendahl Deborah , Harcourt Jonny , Elston Caroline , Simmonds N J , Shah Anand
Published: May 2020

Introduction

Individuals with chronic lung disease (eg, cystic fibrosis (CF)) often receive antimicrobial therapy including aminoglycosides resulting in ototoxicity. Extended high-frequency audiometry has increased sensitivity for ototoxicity detection, but diagnostic audiometry in a sound-booth is costly, time-consuming and requires a trained audiologist. This cross-sectional study analysed tablet-based audiometry (Shoebox MD) performed by non-audiologists in an outpatient setting, alongside home web-based audiometry (3D Tune-In) to screen for hearing loss in adults with CF.

Methods

Hearing was analysed in 126 CF adults using validated questionnaires, a web self-hearing test (0.5 to 4 kHz), tablet (0.25 to 12 kHz) and sound-booth audiometry (0.25 to 12 kHz). A threshold of ≥25 dB hearing loss at ≥1 audiometric frequency was considered abnormal. Demographics and mitochondrial DNA sequencing were used to analyse risk factors, and accuracy and usability of hearing tests determined.

Results

Prevalence of hearing loss within any frequency band tested was 48%. Multivariate analysis showed age (OR 1.127; (95% CI: 1.07 to 1.18; p value<0.0001) per year older) and total intravenous antibiotic days over 10 years (OR 1.006; (95% CI: 1.002 to 1.010; p value=0.004) per further intravenous day) were significantly associated with increased risk of hearing loss. Tablet audiometry had good usability, was 93% sensitive, 88% specific with 94% negative predictive value to screen for hearing loss compared with web self-test audiometry and questionnaires which had poor sensitivity (17% and 13%, respectively). Intraclass correlation (ICC) of tablet versus sound-booth audiometry showed high correlation (ICC >0.9) at all frequencies ≥4 kHz.

Conclusions

Adults with CF have a high prevalence of drug-related hearing loss and tablet-based audiometry can be a practical, accurate screening tool within integrated ototoxicity monitoring programmes for early detection.
Spherical electro-vacuum black holes with resonant, scalar Q-hair
Authors: Herdeiro Carlos A. R. , Radu Eugen
Published: May 2020

The asymptotically flat, spherical, electro-vacuum black holes (BHs) are shown to support static, spherical configurations of a gauged, self-interacting, scalar field, minimally coupled to the geometry. Considering a Q-ball type potential for the scalar field, we dub these configurations Q-clouds, in the test field approximation. The clouds exist under a resonance condition, at the threshold of (charged) superradiance. This is similar to the stationary clouds supported by Kerr BHs, which exist for a synchronisation condition, at the threshold of (rotational) superradiance. In contrast with the rotating case, however, Q-clouds require the scalar field to be massive and self-interacting; no similar clouds exist for massive but free scalar fields. First, considering a decoupling limit, we construct Q-clouds around Schwarzschild and Reissner–Nordström BHs, showing there is always a mass gap. Then, we make the Q-clouds backreact, and construct fully non-linear solutions of the Einstein–Maxwell-gauged scalar system describing spherical, charged BHs with resonant, scalar Q-hair. Amongst other properties, we observe there is non-uniqueness of charged BHs in this model and the Q-hairy BHs can be entropically preferred over Reissner–Nordström, for the same charge to mass ratio; some Q-hairy BH solutions can be overcharged. We also discuss how some well known no-hair theorems in the literature, applying to electro-vacuum plus minimally coupled scalar fields, are circumvented by this new type of BHs.
Airy minima in 4He +28Si elastic and inelastic scattering
Authors: Berezhnoy Yu. A. , Molev A. S.
Published: May 2020

We present the results of the [Formula: see text]-matrix description of the [Formula: see text] elastic and inelastic scattering differential cross-sections between 40 and 240 MeV with allocation of Airy minima of various orders. The first-order Airy minima have been unambiguously identified in the differential cross-sections for elastic scattering and inelastic scattering to the first [Formula: see text] state of [Formula: see text] at energies [Formula: see text] MeV, and the second-order Airy minima — at [Formula: see text] MeV. The angular positions of these minima obey an inverse dependence on energy. The intensities of nuclear refraction and absorption also obey the same energy dependence.
Exploring disease comorbidity in a module–module interaction network
Authors: Hwang Soyoun , Lee Taekeon , Yoon Youngmi
Published: May 2020

Understanding disease comorbidity contributes to improved quality of life in patients who are suffering from multiple diseases. Therefore, to better explore comorbid diseases, the clarification of associations between diseases based on biological functions is essential. In our study, we propose a method for identifying disease comorbidity in a module-based network, named the module–module interaction (MMI) network, which represents how biological functions influence each other. To construct the MMI network, we detected gene modules — sets of genes that have a higher probability of taking part in specific functions — and established a link between these modules. Subsequently, we constructed disease-related networks in the MMI network to understand inherent disease mechanisms and calculated comorbidity scores of disease pairs using Gene Ontology (GO) terms. Our results show that we can obtain further information on disease mechanisms by considering interactions between functional modules instead of between genes. In addition, we verified that predicted comorbid relationships of disease pairs based on the MMI network are more significant than those based on the protein–protein interaction (PPI) network. This study can be useful to elucidate the mechanisms underlying comorbidities for further study, which will provide a broader insight into the pathogenesis of diseases.
Gauge Inverse Monoids
Authors: Schwab Emil Daniel
Published: May 2020

The paper introduces a class of inverse (sub)monoids which contains Jones–Lawson’s gauge inverse (sub)monoid. The aim is to give examples and the basic properties of these monoids. Jones–Lawson’s gauge inverse monoid, as an inverse submonoid of the polycyclic monoid, is the prototype in our development line. The generalization leads also to Meakin–Sapir type results involving bijections between special congruences and special wide inverse submonoids.
On a Graph Related to Subgroups Generated by a Conjugacy Class in Finite Groups
Authors: Robati S.M.
Published: May 2020

Let G be a group, and let [Formula: see text](G) be a digraph whose vertices are the non-trivial conjugacy classes of G and there is an arc from a vertex C to a vertex C′ if and only if C ≠ C′ and 〈C〉 ⊆ 〈C′〉. In this paper, we characterize finite groups G whose associated digraphs [Formula: see text](G) are oriented trees.