bluuebunny/crossref_metadata_2025 huggingface dataset:
Navigating the challenges of Bombay phenotype (Oh) and twin pregnancy; a case report and literature review
Authors: Krigstein Michael , Cromer Natalie
Published: November 2021

Background

Bombay phenotype (Oh) is a rare blood group and poses unique challenges during pregnancy, including an adequate supply of blood products in case of postpartum hemorrhage (PPH) and the risk of hemolytic disease of the fetus and newborn (HDFN). Case reports of antenatal care in this cohort are scarce. Herein, we present a case of twin pregnancy in an Oh woman and outline her multidisciplinary management. We summarize the literature to better inform decision‐making and patient blood management in the antenatal care of Oh women.

Case description

A 22‐year‐old G1P0 presented at 15 weeks gestation with dichorionic diamniotic twins and known Oh phenotype. Hematinics were optimized to minimize anemia. Anti‐H titers were tracked and were 1:256 at both 28 and 36 weeks gestation. Regular middle cerebral artery dopplers were performed to assess for fetal anemia. There was constant communication with obstetrics and anesthetics teams. Both autologous frozen and directly donated fresh red cells were available as part of a clear, detailed transfusion plan. Transfusion was not required and neither child was affected by HDFN. The neonates were group O, DAT negative, and group A, DAT positive. Maternal anti‐A was detected in the neonatal eluate.

Conclusion

To our knowledge, this is only the second report of twin pregnancy in an Oh female and the first time a detailed transfusion plan has been published. Through employing patient blood management strategies, engaging a collaborative multidisciplinary approach, and establishing a clear delivery plan, the antenatal challenges of Bombay phenotype are surmountable.
Mortalidade infantil e orçamento público. Desafios na gestão do sistema de saúde no Território Litoral Sul da Bahia, Brasil
Authors: Pereira da Silva Alciene , Pinto Roque , Menezes Skalinski Lacita , Pereira da Silva Alisson Jadavi , Barbosa Pinto Beatriz , Oliveira Gonçalves Ângelo
Published: November 2021

Este trabalho pretende discutir como o orçamento público e o modelo da atenção básica em saúde pública podem afetar as taxas de mortalidade infantil em um dado território. A investigação foi realizada no Território Litoral Sul da Bahia, no Estado da Bahia, região Nordeste do Brasil. Trata-se de uma pesquisa quantitativa e descritiva, baseada em dados secundários referentes ao período 2006-2015, coletados entre 2017 e 2018, em bancos de dados públicos oficiais brasileiros. Verificou-se que embora a taxa média de mortalidade infantil tenha caído gradativamente a partir de 2006 no território investigado, ela continua maior do que a média nacional em todo o período pesquisado. Em 2006, a taxa média do território foi de 35,53%, e decresceu até 18,56% em 2015. Contudo, em todo o período a taxa média permaneceu maior do que a média brasileira, que é de 18%. Os índices de mortalidade infantil têm forte relação com fatores sociais, econômicos e ambientais. No caso investigado, estão associados à fragmentação e a fragilidade das redes públicas de serviços de saúde nos municípios da região.
Climatology and Trends of Heat Index, Human Discomfort Index, and Energy Per Capita for CONUS and Meso-America
Authors: Faiz Qurat , González Jorge E.
Published: November 2021

Air temperature and humidity affect human comfort and health in warm and humid climates, and consequently energy demands from buildings to maintain indoor comfort levels. An effective way to measure the overall effect of temperature and humidity on human comfort (or discomfort) is using the heat index (HI), a measure of how people “feel” when exposed to warm and humid environments. This research aims to investigate the spatial and temporal changes and trends of HI and associated energy per capita (EPC) to maintain human comfort in the Continental US (CONUS) and the Meso-America (the Caribbean, and Northern Regions of South America). Hourly air temperature and relative humidity datasets were collected from three sources: the National Center for Environmental Prediction, the North American Regional Reanalysis (NARR), and surface weather stations for a period of 30 years: 1990–2019. The algorithm used for the HI is similar to the one used by the US National Weather Service whereas the EPC is based on the ventilation requirements per person. Results for HI and EPC climatology for the summer season indicate the largest increasing values in Southeast US, followed by the Greater Antilles, and then the Lesser Antilles. Results of the analysis depict positive EPC rate of 2 kW h per year for the summer season for the Southern Greater Antilles. These trends using NARR data were found to be statistically significant and correlate very well with selected weather stations. The actual trends of electricity consumption per person per year for the CONUS suggest, in general, a correlation with increasing maximum HI.
Indentation Tests for Sintered Silver in Die-Attach Interconnection After Thermal Cycling
Authors: Qin Fei , Zhao Shuai , Dai Yanwei , Liu Lingyun , An Tong , Chen Pei , Gong Yanpeng
Published: November 2021

Thermomechanical reliability assessment for sintered silver is a crucial issue as sintered silver is a promising candidate of die-attachment materials adopted for power devices. In this paper, the nano-indentation tests are performed for sintered silver in typical die-attach interconnection under different thermal cycles. Based on thermal cycling test, the Young's modulus and hardness of sintered silver layer have been presented. It is found that the Young's modulus and hardness of sintered silver layer changes slightly although the microstructure of sintered silver also presents some variations. The stress and strain curves for different thermal cycling tests of sintered silver are also given based on reverse analysis of nano-indentation. The results show that the elastoplastic constitutive equations change significantly after thermal cycling tests, and the yielding stress decreases remarkably after 70 thermal cycles. The experimental investigation also shows that the cracking behaviors of sintered silver depend on its geometry characteristics, which implies that the possible optimization of sintered silver layer could enhance its thermomechanical performance.
A Comparative Analysis of Artificial Neural Networks for Photovoltaic Power Forecast Using Remotes and Local Measurements
Authors: Lopes Sofia M. A. , Cari Elmer P. T. , Hajimirza Shima
Published: November 2021

The inclusion of photovoltaic systems in distribution networks has raised the importance of the prediction of photovoltaic power for safe planning and operation. Artificial neural networks (ANNs) have been used in this task due to its capacity of representing nonlinearities. However, the profile of the data used may affect the forecast accuracy. This manuscript reports on a comparative analysis of the performance of four neural network models for photovoltaic power forecast regarding their input dataset. Four sets composed of photovoltaic power data (local measurements) and external weather data (remote measurements) were used, and the networks were validated through actual measurements from a photovoltaic micro plant. The ANN that dealt with only weather data showed a good level of accuracy, being a useful tool for the feasibility analysis of new photovoltaic projects. In addition, the approach that used only photovoltaic power data has excelled and can be used in electric sector companies.
Testing the Modified Subchannel tempa-sc Code in Comparison With Experiments and Other Computer Codes
Authors: Baisov A. M. , Churkin A. N. , Deev V. I. , Kharitonov V. S.
Published: November 2021

The paper describes a modified version of the tempa-sc computer program designed to calculate temperature fields in bundles of rods cooled by a supercritical pressure (SCP) fluid. This version of the program is based on the subchannel method that was used in the tempa-1f program, developed earlier in the OKB “GIDROPRESS” for calculating heat and mass transfer in the core of VVER-type reactors cooled by single-phase water at subcritical pressure. As the relations that close the system of equations of mass, momentum, and energy conservation, the new version of the program includes correlations for calculating heat transfer and friction resistance, taking into account the strong dependence of the properties of the coolant on temperature and pressure. In particular, the use of the universal calculation model of heat transfer, developed by the authors of this paper, allows us to perform calculations in a wide range of flow parameters of various fluids, including the modes of normal, improved and deteriorated heat transfer. The results of tests of the tempa-sc program are presented in comparison with the available experimental data for water and modeling fluids (carbon dioxide, freons R-12 and R-134a) at SCPs, as well as with the published data of calculations by using similar subchannel programs (cobra-sc, assert-pv) and CFD codes. A qualitative agreement between the calculated and experimental data is shown.
Subharmonic Resonance of Two Thirds Order of Electrostatically Actuated Bio-MEMS Circular Plates: Amplitude-Frequency Response
Authors: Caruntu Dumitru I. , Beatriz Julio , Alipi Marcos
Published: November 2021

This paper deals with subharmonic resonance of two thirds order or electrostatically activated BioMEMS circular plates. Specifically, this paper investigates the frequency amplitude response of this resonance. The system consists of a clamped flexible circular plate above a parallel electrode situated at a distance, and under an AC voltage of frequency near three fourths of the natural frequency of the plate. The method of multiple scales is used to model the hard excitations in the system, hard excitations that are necessary to produce this secondary resonance. This work predicts the response, as well as the effects of parameters such as voltage and damping on the response. This paper predicts that the subharmonic resonance of two thirds order consists of a near zero steady state amplitude, and higher values steady state amplitudes consisting of a stable branch and an unstable branch, and a saddle-node bifurcation point. The predictions regarding the effects of voltage and damping on the response of the BioMEMS plate shows that as the voltage increases, the bifurcation point is shifted to lower frequencies and lower amplitudes, while as the damping increases the bifurcation point is shifted to lower frequencies and high amplitudes. Therefore, the increase of damping leads to a case in which it is harder to reach higher amplitude steady-state solutions since it requires large initial amplitudes of the plate.
Using Physics-Informed Generative Adversarial Networks to Perform Super-Resolution for Multiphase Fluid Simulations
Authors: Li Matthew , McComb Christopher
Published: November 2021

Computational Fluid Dynamics (CFD) simulations are useful to the field of engineering design as they provide deep insights on product or system performance without the need to construct and test physical prototypes. However, they can be very computationally intensive to run. Machine learning methods have been shown to reconstruct high-resolution single-phase turbulent fluid flow simulations from low-resolution inputs. This offers a potential avenue towards alleviating computational cost in iterative engineering design applications. However, little work thus far has explored the application of machine learning image super-resolution methods to multiphase fluid flow (which is important for important for emerging fields such as marine hydrokinetic energy conversion). In this work, we apply a modified version of the Super-Resolution Generative Adversarial Network (SRGAN) model to a multiphase turbulent fluid flow problem, specifically to reconstruct fluid phase fraction at a higher resolution. Two models were created in this work, one with a simple physics-constrained loss function and one without, and the results are discussed and analyzed. We found that both models were able to significantly outperform non-machine learning upsampling methods and can preserve an impressive amount of detail and nuance, showing the versatility of the SRGAN model for upsampling fluid simulations. However, the difference in accuracy between the two models is quite minimal. This indicates that, for these contexts studied here, the additional complexity of a physics-informed approach may not be justified.
A Numerical and Experimental Study on the Energy Absorption Characteristics of Deployable Origami Tubes
Authors: Wo Zhongyuan , Raneses Julia M. , Filipov Evgueni T.
Published: November 2021

Energy absorption devices are widely used to mitigate damage from collisions and impact loads. Due to the inherent uncertainty of possible impact characteristics, passive energy absorbers with fixed mechanical properties are not capable of serving in versatile application scenarios. Here, we explore a deployable design concept where origami tubes can extend, lock, and are intended to absorb energy through crushing (buckling and plasticity). This system concept is unique because origami deployment can increase the crushing distance between two impacting bodies and can tune the energy absorption characteristics. We show that the stiffness, peak crushing force, and total energy absorption of the origami tubes all increase with the deployed state. We present numerical and experimental studies that investigate these tunable behaviors under both static and dynamic scenarios. The energy-absorbing performance of the deployed origami tubes is slightly better than conventional prismatic tubes in terms of total absorbed energy and peak force. When the origami tubes are only partially deployed, they exhibit a nearly-elastic collapse behavior, however, when they are locked in a more deployed configuration they can experience non-recoverable crushing with higher energy absorption. Parametric studies reveal that the geometric design of the tube can control the nonlinear relationship between energy absorption and deployment. This concept for deployable energy-absorbing origami tubes can enable future protective systems with on-demand properties for different impact scenarios.
A Hypergraph-Based Knowledge Representation Model for Smart Product-Service System Development
Authors: Zuoxu Wang , Xinyu Li , Chun-Hsien Chen , Pai Zheng
Published: November 2021

In the trend of digital servitization, manufacturing companies have been transforming their business paradigms to Smart product-service systems (Smart PSS) by integrating products and associated services as bundles. To support the knowledge-intensive process of Smart PSS development, massive domain knowledge should be well-organized and reused. However, due to the existence of non-binary relations caused by product-service bundles (PSB) and context-awareness concerns in the Smart PSS development activities, conventional graph-based approaches for knowledge representation may lose essential information in transforming non-binary relations into binary ones, and hence cause incorrect results in the subsequent knowledge queries. To mitigate this problem, a hypergraph-based knowledge representation model for Smart PSS was proposed, which represents the non-binary relations among multiple entities with hyperedges. Technically, the knowledge source and the typical hyperedge schema in Smart PSS development are identified in this paper. A detailed case study in the scenarios of 3D printing troubleshooting and PSB recommendation was conducted to showcase the proposed hypergraph-based knowledge representation model and demonstrate its validity. The results show that the hypergraph-based knowledge model significantly relieves the sparsity in the ordinary KG by adding multiple hyperedges. It is anticipated that the proposed hypergraph knowledge representation model can serve as a fundamental study for further knowledge reasoning activities.
Serial Chain of Rigid Origami That Extends, Bends and Turns
Authors: Kamijo Haruto , Tachi Tomohiro
Published: November 2021

This paper presents a family of serial chain mechanisms with three degrees of freedom (DOF) by concatenating rigid origami modules. This chained mechanism forms a circular arc shape and can continuously extend, bend, and turn. The mechanism keeps three-DOF regardless of the number of connected modules, and the whole motion can be controlled by determining the configuration of one module at the end. We first describe the geometric construction of the mechanism and its implementation as a rigid origami fabricated from a flat sheet. We then analyze the kinematics of the system to illustrate the configuration space and how the shapes change by manipulating the input parameters. We also synthesize the motions by numerically solving inverse kinematics of the system. We also propose novel torus mechanism with two DOF.
Enabling Artificial Intelligence Studies in Off-Road Mobility Through Physics-Based Simulation of Multi-Agent Scenarios
Authors: Young Aaron , Taves Jay , Elmquist Asher , Serban Radu , Negrut Dan , Benatti Simone , Tasora Alessandro
Published: November 2021

We describe a simulation environment that enables the development and testing of control policies for off-road mobility of autonomous agents. The environment is demonstrated in conjunction with the design and assessment of a reinforcement learning policy that uses sensor fusion and inter-agent communication to enable the movement of mixed convoys of human-driven and autonomous vehicles. Policies are learned on rigid terrain and are subsequently shown to transfer successfully to hard (silt-like) and soft (snow-like) deformable terrains. The enabling simulation environment is developed from the high fidelity, physics-based simulation engine Chrono. Five Chrono modules are employed herein: Chrono::Engine, Chrono::Vehicle, PyChrono, SynChrono and Chrono::Sensor. Vehicle’s are modeled using Chrono::Engine and Chrono::Vehicle and deployed on deformable terrain within the training/testing environment. Utilizing the Python interface to the C++ Chrono API called PyChrono and OpenAI Gym’s supporting infrastructure, training is conducted in a GymChrono learning environment. The GymChrono-generated policy is subsequently deployed for testing in SynChrono, a scalable, cluster-deployable multi-agent testing infrastructure built on MPI. SynChrono facilitates inter-agent communication and maintains time and space coherence between agents. A sensor modeling tool, Chrono::Sensor, supplies sensing data that is used to inform agents during the learning and inference processes. The software stack and the Chrono simulator are both open source. Relevant movies: [1].
Multi-Objective Robust Design Exploration of a Canine Ventricular Shunt for Managing Hydrocephalus
Authors: Sharma Gehendra , Nellippallil Anand Balu , Yingling Ryan , Lee Na Yeon , Shores Andy , Miralami Raheleh , Stone Tonya W. , Prabhu Raj K.
Published: November 2021

Hydrocephalus is characterized by the abnormal accumulation of cerebrospinal fluid (CSF) within the ventricles of the brain, resulting in an increase of intracranial pressure (ICP). Ventriculoperitoneal shunts (VPS) are designed to prevent buildup of pressure in the brain by allowing excess CSF flow from the intracranial ventricles to the peritoneal cavity through a shunting mechanism. The shunt design presented in this paper is an inexpensive alternative to VPS, that is, a non-valve ventricular shunt design that directly routes CSF into the subarachnoid space.

We recognize that consideration of multiple design criteria and uncertainty management are critical for designing biomedical devices to ensure robust performance. Hence, our objective in this paper is to present a multi-objective robust design exploration of canine shunts for managing hydrocephalus. Our approach in robust design focuses on managing uncertainties to deliver design solutions that are relatively insensitive to uncertainties. Hence, a multi-objective robust design problem is formulated using the compromise Decision Support Problem (cDSP) construct to explore shunt designs that best satisfy the conflicting goals dealing with the pressure difference and the stress, and a robust design goal dealing with the variations in pressure difference. We compare the results against optimal solutions to build confidence in the proposed method to identify design solutions that are relatively insensitive to uncertainties. The method presented is generic and can be applied to the multi-objective robust design of similar biomedical devices.
The Kinematic Analysis and Bistable Characteristics of the Winding Origami Structure
Authors: Liu Peng , Ma Jiayao , Chen Yan , Yuan Lin , Zhao Haifeng , Wang Ke
Published: November 2021

In the military and aerospace fields, bistable structures with adjustable or adaptive stiffness have been widely applied. Origami structures can be used to design bistable systems due to their unique geometrical characteristics. In this paper, we investigate a special design of winding origami, which consists of a square hub in the center and compactly folded panels around it. This delicate design provides the structure a bistable property. According to its motion characteristics, the folding process of the winding origami can be divided into two stages: the mechanism motion stage and the structural deformation stage. The D-H matrix method and truss transformation method were combined to analyze the kinematic relations, and the winding origami pattern was found to have one degree of freedom. At the structural deformation stage, the mechanical response and the local panel deformation were carefully studied via both experiments and finite element simulations, and a reasonable agreement was reached. It was observed that four creases exhibited a non-uniform folding pattern during the deformation process; that is, a portion of the crease was totally flattened while the rest remained folded. The origami structure’s unique kinematic and bistable features could possibly help provide some new ideas in designing a bistable system in the future.
The Development and Testing of Pour-Flush Toilet Sensors for Understanding User Interaction in Peri-Urban Households
Authors: Cotera Rivera Pablo , Bilton Amy M.
Published: November 2021

Rapid worldwide urbanization has created peri-urban environments that often lack services and infrastructure for water and sanitation. Globally, around 4.5 billion people do not have access to safely managed sanitation, as is often the case in such environments. Efforts to develop appropriate sanitation alternatives in these contexts recognize the value of understanding users’ preferences and interaction with their sanitation systems, however, the traditional tools for assessing technology usage and adoption are based on physical observation, which presents limitations. In this work, we developed a toilet sensor to identify usage patterns of pour-flush toilets by quantifying flushing and defecation events. The device has a methane gas sensor, IR distance sensor and a motion sensor connected to a microcontroller. Its small footprint allows for unobtrusive installation inside a toilet bowl and operates battery-powered for about 5 days depending on usage patterns. To evaluate the sensor performance, units were installed for a field trial in nine participants’ households in a Mexican peri-urban community and an algorithm for automated data analysis was developed. Surveys were also conducted to benchmark the sensor performance and determine the potential value of the approach. Results showed that on average people underreported their daily toilet usage by two events compared to the measurements and they flushed only 75% of the time after defecation. By monitoring the usage of the current pour-flush toilets lacking piped water and sewerage and complementing the data with users’ feedback, we can gain an understanding of the existing limitations so more suitable sanitation alternatives can be proposed.
Computational Design and 3D Weaving of 2D-Printable Conformal Flexible Electronics Using Harmonic Foliation Theory
Authors: Ye Qian , Guo Yang , Gu Xianfeng David , Chen Shikui
Published: November 2021

This paper proposes a new way of designing and fabricating conformal flexible electronics on free-form surfaces, which can generate woven flexible electronics designs conforming to free-form 3D shapes with 2D printed electronic circuits. Utilizing our recently proposed foliation-based 3D weaving techniques, we can reap unprecedented advantages in conventional 2D electronic printing. The method is based on the foliation theory in differential geometry, which divides a surface into parallel leaves. Given a surface with circuit design, we first calculate a graph-value harmonic map and then create two sets of harmonic foliations perpendicular to each other. As the circuits are processed as the texture on the surface, they are separated and attached to each leaf. The warp and weft threads are then created and manually woven to reconstruct the surface and reconnect the circuits. Notably, The circuits are printed in 2D, which uniquely differentiates the proposed method from others. Compared with costly conformal 3D electronic printing methods requiring 5-axis CNC machines, our method is more reliable, more efficient, and economical. Moreover, the Harmonic foliation theory assures smoothness and orthogonality between every pair of woven yarns, which guarantees the precision of the flexible electronics woven on the surface. The proposed method provides an alternative solution to the design and physical realization of surface electronic textiles for various applications, including wearable electronics, sheet metal craft, architectural designs, and smart woven-composite parts with conformal sensors in the automotive and aerospace industry. The performance of the proposed method is depicted using two examples.
Multi-Material Topology Optimization of Ferromagnetic Soft Robots Using Reconciled Level Set Method
Authors: Tian Jiawei , Gu Xianfeng David , Chen Shikui
Published: November 2021

Ferromagnetic soft materials can generate flexible mobility and changeable configurations under an external magnetic field. They are used in a wide variety of applications, such as soft robots, compliant actuators, flexible electronics, and bionic medical devices. The magnetic field enables fast and biologically safe remote control of the ferromagnetic soft material. The shape changes of ferromagnetic soft elastomers are driven by the ferromagnetic particles embedded in the matrix of a soft elastomer. The external magnetic field induces a magnetic torque on the magnetized soft material, causing it to deform. To achieve the desired motion, the soft active structure can be designed by tailoring the layouts of the ferromagnetic soft elastomers. This paper aims to optimize multi-material ferromagnetic actuators. Multi-material ferromagnetic flexible actuators are optimized for the desired kinematic performance using the reconciled level set method. This type of magnetically driven actuator can carry out more complex shape transformations by introducing ferromagnetic soft materials with more than one magnetization direction. Whereas many soft active actuators exist in the form of thin shells, the newly proposed extended level set method (X-LSM) is employed to perform conformal topology optimization of ferromagnetic soft actuators on the manifolds. The objective function comprises two sub-objective functions, one for the kinematic requirement and the other for minimal compliance. Shape sensitivity analysis is derived using the material time derivative and the adjoint variable method. Three examples are provided to demonstrate the effectiveness of the proposed framework.
Extending Usage Context-Based Design to Coupled Usage Contexts: A Vehicle Design Case Study
Authors: Arezoomand Mojtaba , Austin-Breneman Jesse
Published: November 2021

Engineers must consider the usage context of a product in order to both predict its technical performance and model customer preferences. An emerging body of work in Decision-based Design (DBD) has elaborated various approaches for modeling the usage context in order to better predict customer choice behavior and select optimal product attributes. Building on this prior work, this study proposes a new method for formulating DBD problems in which product attribute values can change contextual factors. Results from a vehicle design case study demonstrate the utility of the proposed method for understanding how phenomena such as the rebound effect and induced travel demand connect system-level outcomes to design changes. This study suggests that the Design for Coupled Usage Contexts framework is a promising tool to further explore as a way to support designers making decisions which involve these types of mechanisms. Further exploration should include additional case studies to investigate other coupling mechanisms and design tasks.
AgBug: Agricultural Robotic Platform for In-Row and Under Canopy Crop Monitoring and Assessment
Authors: Manish Raja , An Ze , Habib Ayman , Tuinstra Mitchell R. , Cappelleri David J.
Published: November 2021

This paper focuses on the development of a small scale agricultural robotic platform with advantages over the current agricultural phenotyping platforms that lack the size-scale and sensor resolution needed to study hard to reach under-canopy row crops. The AgBug utilizes a sensor suite consisting of a LiDAR and RGB camera for crop monitoring on a 12″ × 9″ footprint platform. The main challenge for this platform design is not only its compact size and portability, but its ability to navigate and obtain geo-referenced and time-tagged data in the GNSS-denied environment that exists under the crop canopy. LiDAR and RGB sensors typically rely on inputs from GNSS data. Therefore, a new approach was developed here fusing direct feedback from the RGB camera and a visual-inertial tracking camera supplying robot odometry data. Indoor and outdoor tests were conducted to demonstrate the AgBug’s ability for in-row and under canopy crop monitoring along with the efficacy of sensor fusion approach.
Mathematical and Computational Modeling of Resistance Spot Welding Solidification Process
Authors: Sun Ruiji , Higgins Matthew , Zhang Haiyan H.
Published: November 2021

The paper presents a mathematical model and simulation of resistance spot welding (RSW) of a binary alloy during the final solidification process. After analyzing the heat distribution and heat transfer process, the authors established assumptions for a planar front solidification model. Following the application of initial and boundary conditions, the model is developed numerically to describe the thermal distribution in the resistance spot welding system as a function of position and time. For each value in the time array, a heat transfer profile through the welding sheet is calculated as a piecewise function. The model is further executed with Python, which allows customized inputs of resistance spot welding parameters. Finally, the heat transfer model is simulated with COMSOL Multiphysics in the specific example of 1050 mild steel. Heat transfer module is applied to the proposed mathematical model, and simulation of temperature profile and thermal gradient of the welding zones are developed. The simulation further confirms the mathematical model and provides a demonstration that the temperature decreases through both the water-cooled welding tips and thermal diffusion to the surrounding metal sheets, leading to adjacent heat-affected zones. The model is intended for predicting the resistance spot welding nugget solidification process, as well as to help analyze the effects of welding parameters to achieve a weld nugget of optimal size.
Selection Method of Molding Condition for Self-Adhesive Products Using Only Bamboo Fibers Extracted With a Machining Center Based on Bayesian Optimization
Authors: Tauchi Daigo , Hirogaki Toshiki , Aoyama Eiichi , Ogawa Keiji , Nobe Hiromichi
Published: November 2021

Bamboo grows naturally in Japan as an underutilized forest resource, and its fibers have high specific strength and stiffness, so much so that they are called natural glass fibers. In this study, a method for manufacturing a self-adhesive compact material by pressurizing and heating 100% bamboo fiber after extraction using a machining center, without losing the composition of bamboo, is proposed. This molded body is made of a 100% natural material and has a low environmental impact even when landfilled, contributing to the growth of bamboo for use as a raw material.

In this study, the formation conditions for maximizing the tensile properties when forming platelets were investigated. First, an analysis of the variance was conducted using the orthogonal array test design to identify the factors affecting the objective variable and determine the contribution of each factor. In addition, estimates of the objective variable for the molding conditions were obtained from the Gaussian process regression model in a Bayesian optimization. Furthermore, as a result of comparing the maximum values of the properties of the molding conditions between the analysis of variance and the Gaussian process regression model, the values of the tensile properties were improved in the Gaussian process regression model.
System Design Priority Order Considering Uncertainty in Early Stages
Authors: Kuroyanagi Takumi , Yamada Shuho , Hiramatsu Shigeki , Unesaki Hiroshi , Kondo Shuichi , Aoyama Kazuhiro
Published: November 2021

Herein, we have confirmed the importance of formulating product proposals and product-development processes equipped to cope effectively with uncertainty in the early design stage. The objective of this study was to derive the target performance and design priority order taking into account uncertainties in system design.

Following the concept of set-based design, the approach adopted was to secure a set of solutions as design space that satisfy the target variables demands, dividing the design space into several clusters and evaluating each of the clusters, then gradually narrowing the cluster as the design progresses, and finally extracting the solution space that is desirable. Priority order of design was developed based on the strategy of increasing the degree of freedom of the subsequent process.

The effectiveness of the proposed method was verified using the model of a plug-in hybrid vehicle. From the results, we confirmed the existence of a trade-off between design and target variables preference and development risk, that it is possible to determine the extent to which the solution space can be narrowed, that the shape of the solution space determines the design priorities, and we were able to derive a desirable design priority order according to the target performance.
Fractional Active Disturbance Rejection Controller Based on Improved Differential Evolution Algorithm
Authors: Liang Henghui , Yu Wei , Chen Rui , Luo Ying
Published: November 2021

Although the active disturbance rejection controller can obtain good control performance without relying on specific model information, it targets integer-order systems. Fractional-order characteristics are commonly existed in practical systems. For fractional-order systems, it is more targeted to use the order information of the fractional-order model to design the active disturbance rejection controller, so as to obtain better control performance. A fractional active disturbance rejection controller composed of FOESO and FOPID (IDE-FOPID-FOESO) is proposed in this paper. The fractional-order extended state observer (FOESO) is designed based on the order information and the nonlinear state error feedback is replaced by the fractional-order PID controller (FOPID) whose parameters are obtained by the improved differential evolution algorithm (IDE). For IDE algorithm, the basis vector is randomly selected from the optimal individual population in the mutation strategy, and the scaling factor and cross-probability factor are adaptively adjusted according to the information of the successfully mutated individual in the search process to improve the exploration and mining capabilities of the algorithm. The simulation results show that the IDE algorithm can obtain the better parameters of FOPID faster compared with traditional DE algorithm and the IDE-FOPID-FOESO controller can be better applied to fractional-order systems with better control performance.
Finite Element Modeling of Geometrically Exact Shell With Large Deformation and Rotation
Authors: Wang Jielong
Published: November 2021

This paper developed a new geometrically exact shell element to model the relatively thin structures with large deformations and arbitrary rigid motions. The deformations were well decoupled from rigid motions by using the direct modeling approach. The rotation-free Green-Lagrange strain tensor described the large deformations together with geometrical nonlinearities. Meanwhile, the Wiener-Milenković parameter was applied to vectorial parameterize the arbitrary rotations of the fiber avoiding the singularities usually occurred in the classical shell formula. This paper also designed a new interpolating algorithm without losing objectivity to discretize the vectorial parameters, which improves the robustness of new shell element. The application of Mixed Interpolation of Tensorial Components with 9 nodes (MITC9) makes the shell element shear-locking free and with second-order accuracy. Each node contains five degrees of freedom, three for translations and two for rotations, achieving a minimal set representation of arbitrary motions. These innovations contribute to a new shell formula featuring high computational efficiency with good accuracy. Finally, two flexible multibody dynamic models are discretized by this new shell element. The numerical simulation results of the new shell element have been verified to demonstrate the capability of new shell element dealing with large deformations and arbitrary motions of thin structures.
Nonlinear Finite Element Based Contact Modeling for Bolted Joints in Composite Laminates
Authors: Wang Jielong
Published: November 2021

The paper developed a new numerical joint model based on nonlinear finite element method for the multiple bolted joints in composite laminates. The new joint model consists of the geometrically exact beam and shell elements, as well as the new Hertz contact elements. The geometrically exact elements, beams and shells, are used to model the bolts and laminates with nonlinear deformations, respectively. Meanwhile, the new contact elements apply the Hertz model to simulate the contact, slippage and bolt-laminate interaction. This contact element combined with the multi-point constraints to transfer the shear forces from one shell through beam to another shell element. As an essential part of the bolted joint model, a new type of geometrically exact shell element was developed with second-order accuracy and nine nodes. The strain-displacement relationship of this shell element was formulated according to the rotation-free Green-Lagrange strain tensor. This shell element approximated the higher-order components of strain tensor, ensuring it can accurately describes the real deformation of thin-walled composite laminates. Application of this joint model to a three-bolt, single-shear joint in composite laminates was presented, and its predictions are compared with those of commercial code ABAQUS. Numerical simulation results show that the new joint model is suitable for the design of bolted joints in composite laminates with good accuracy and high efficiency.
Inhomogeneous Folding Modes in Infinite Lattices of Rigid Triangulated Miura-ori
Authors: Lahiri Anandaroop , Pratapa Phanisri P.
Published: November 2021

Infinite two-dimensional tessellations of triangulated Miura-ori with rigid panels are known to exhibit only homogeneous modes of folding, thereby limiting their usefulness in engineering applications. In this work, we show that the corresponding one-dimensional lattices are less restricted and can exhibit inhomogeneous folding modes of deformation. We demonstrate this by looking at the modes in the null space of Bloch-reduced compatibility matrix in a nodal-displacement-based formulation, that is typically employed in the context of origami structural analysis. We compute the deformation modes that vary non-uniformly across the lattice depending on their wavelength, and identify the minimal number of modes that can represent such deformations. We then present a more efficient formulation based on folding-angles to study the deformation modes of infinite one-dimensional rigid triangulated origami lattices. We derive the degrees of freedom of the tessellations in terms of the minimal number of folding-angles that are required to capture the periodic inhomogeneous deformations of the infinite lattices. Within this formulation, we provide the framework to analytically derive the stiffness matrix of the lattice. Finally, we verify the new formulation by comparing the results with the bar-and-hinge model that is based on nodal-displacements. The observations from our work could have implications for the use of rigid panel origami lattices as acoustic metamaterials.
A Contactless Classification Method for Early Detection of Nematodes Using Deep Neural Networks (DNNs) and TensorFlow
Authors: Niu Haoyu , Westphal Andreas , Chen YangQuan
Published: November 2021

Soil-borne plant-parasitic nematodes are microscopic, eellike roundworms. The root-knot nematodes (Meloidogyne spp.) and root-lesion nematodes (Pratylenchus vulnus) are among the most damaging in California, which are difficult to control and can spread easily in soil on tools, boots, and infested plants. Root-knot nematodes can attack many different crops, including nut and fruit trees, usually cause unusual swellings, called galls, on affected plants’ roots. It is not easy to recognize the infestations of these nematodes. For instance, researchers need to dig up walnut trees with symptoms, wash or gently tap the soil from the roots, and examine the roots for galls. The nematode extraction procedures, identification, and enumeration under a microscope are tedious and time-consuming. Therefore, in this article, the authors proposed to use a low-cost contactless radio frequency tridimensional sensor “Walabot,” and Deep Neural Networks (DNNs), to perform the early detection of nematodes in a walnut site. Radiofrequency reflectance of walnut leaves from different nematode infestation levels was measured. The hypothesis was that waveforms generated from walnut leaves can estimate the damage caused by nematodes. DNNs with Tensor-Flow were used to train and test the proposed method. Results showed that the Walabot predicted nematode infestation levels with an accuracy of 82%, which showed great potentials for early detection of nematodes.
Design, Modeling and Ride Analysis of Energy-Harvesting Hydraulically Interconnected Suspension
Authors: Qin Bonan , Chen Yuzhe , Zuo Lei
Published: November 2021

This paper introduces a novel energy-harvesting hydraulically interconnected suspension (EH-HIS) to improve the riding comfort and road handling performance for off-road vehicles while harvesting the vibration energy traditionally dissipated into heat by the oil shock absorbers. To understand the system, we built a model of the off-road vehicle equipped with the EH-HIS and conducted the performance analysis. The system model is established based on the pressure drop principle and validated by commercial simulation software AMESim. The damping characteristic and energy harvesting performance have been investigated based on the mathematical suspension model. Further, a thorough analysis is implemented to compare the dynamic responses of the vehicle equipped with the traditional suspension and EH-HIS under different driving speeds and road classes. Results show that the EH-HIS system can provide tunable asymmetric damping from 3134 Ns/ to 7558 Ns/m, which covers most of the damping range of the off-road vehicles. The average regenerative power of the half EH-HIS system reaches 438 watts, and the corresponding hydraulic efficiency reaches 19%, at a vibration input of 2 Hz frequency and 30 mm amplitude. The ride analysis shows that the vehicle equipped with the EH-HIS system on the D class road has good handling stability and better ride comfort over the traditional suspension.
Quantifying the Predictive Abilities of Speculative Fiction: A Feasibility Study
Authors: Xu Wanyu , Kotecha Maulik C. , Padilla Diego , Jimenez Juliette , McAdams Daniel A.
Published: November 2021

In this article, we explore the capability of speculative fiction to predict future realized technologies. We review a large set of speculative technologies introduced in speculative fiction to determine if the technologies were subsequently realized. Additionally, we explore the time between the speculated introduction and actual realization. Our dataset for analysis is built from the ‘Technovelgy’ database of speculative technologies. A realization assessment methodology is created that includes detailed rubrics to rate and quantify the predictability or realizability of speculative technologies. Three independent raters perform realization assessments for each entry. An inter-rater agreement analysis is carried out to validate the rating method. Based on the dataset of 3095 speculated technologies, 45% are labeled as ‘realized’ by at least one rater. A moderate overall agreement with a Fleiss’ Kappa of 0.57 is reached by all raters. The average time to realization of realized technologies is approximately 45 years with a standard deviation of approximately 34 years. We observe patterns in the realization of speculative technologies and analyze the underlying reasons preventing the technologies from realization. We conclude that speculative fiction predicts future technologies to such a degree that the introduction of speculative technology can be used as an input to designer decision-making.
Mathematical Elucidation of the Traditional Japanese Fan Focusing on Its Structure
Authors: Yamazaki Keiko , Abe Fujiko , Hagiwara Ichiro
Published: November 2021

The Japanese traditional fan, which is a form of origami originating in Japan with a folding culture, has a variety of three-dimensional expression that differs from two-dimensional expression. The image painted on the fan deforms when the fan is folded. In this study, we create a digital fan model for clarifying the deformation on the fan face according to parameters such as length of the bamboo bones. We then validate the digital model with an actual fan. Furthermore, we obtain the original plan view from images of the folded fan as a reverse problem. Because folding fans are made of paper and bamboo and held in the hand, old traditional folding fans are more or less damaged; for example, many culturally valuable folding fans have lost their bones and have damaged edges, have been stretched flat, and have been framed like paintings. Reproducing the original fan without information of the original form is difficult. In the present study, we provide a digital fan model for examining the original fan shape. Old valuable folding fans are treasured by museums and collectors around the world. In future research, we would like to capture such precious folding fans in three-dimensional space applying our digital fan model and to exhibit these fans in a digital museum, providing opportunities not only to enjoy the value of the fans but also to encourage the research of Japanese traditional culture.