bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of excitation‐contraction coupling at the Drosophila neuromuscular junction
Authors: Ormerod Kiel G. , Scibelli Anthony E. , Littleton J. Troy
Published: November 2021

The Drosophila neuromuscular system is widely used to characterize synaptic development and function. However, little is known about how specific synaptic alterations effect neuromuscular transduction and muscle contractility, which ultimately dictate behavioural output. Here we develop and use a force transducer system to characterize excitation‐contraction coupling at Drosophila larval neuromuscular junctions (NMJs), examining how specific neuronal and muscle manipulations disrupt muscle contractility. Muscle contraction force increased with motoneuron stimulation frequency and duration, showing considerable plasticity between 5 and 40 Hz and saturating above 50 Hz. Endogenous recordings of fictive contractions revealed average motoneuron burst frequencies of 20–30 Hz, consistent with the system operating within this plastic range of contractility. Temperature was also a key factor in muscle contractility, as force was enhanced at lower temperatures and dramatically reduced with increasing temperatures. Pharmacological and genetic manipulations of critical components of Ca2+ regulation in both pre‐ and postsynaptic compartments affected the strength and time course of muscle contractions. A screen for modulators of muscle contractility led to identification and characterization of the molecular and cellular pathway by which the FMRFa peptide, TPAEDFMRFa, increases muscle performance. These findings indicate Drosophila NMJs provide a robust system to correlate synaptic dysfunction, regulation and modulation to alterations in excitation‐contraction coupling.

Key points

Larval muscle contraction force increases with stimulation frequency and duration, revealing substantial plasticity between 5 and 40 Hz.

Fictive contraction recordings demonstrate endogenous motoneuron burst frequencies consistent with the neuromuscular system operating within the range of greatest plasticity.

Genetic and pharmacological manipulations of critical components of pre‐ and postsynaptic Ca2+ regulation significantly affect the strength and time course of muscle contractions.

A screen for modulators of the excitation‐contraction machinery identified a FMRFa peptide, TPAEDFMRFa and its associated signalling pathway, that dramatically increases muscle performance.

Drosophila serves as an excellent model for dissecting components of the excitation‐contraction coupling machinery.
Análisis de eficiencia técnica de las unidades de gestión local del Instituto Nacional de Servicios Sociales para Jubilados y Pensionados (Argentina)
Authors: Geri Milva , González Gisela Paula , Villareal Fernanda , Virdis Juan Marcelo
Published: November 2021

Objetivo: determinar cuáles Unidades de Gestión Local (UGL) del Instituto Nacional de Servicios Sociales para Jubilados y Pensionados (INSSJyP) se desempeñan con ineficiencia técnica y/o de escala, así como identificar las UGL de referencia que las unidades ineficientes deberían imitar. Métodos: mediante un análisis envolvente de datos con rendimientos variables se estimó la eficiencia técnica y de escala de las UGL, incluyendo 3 insumos (número de médicos de cabecera, número de puntos de vacunación y número de geriátricos) y 4 productos (número de consultas, número de recetas, número de vacunados contra la gripe y número de internados en geriátricos). Esta información fue obtenida de datos abiertos del INSSJyP. Resultados: se identificaron 14 unidades con eficiencia plena, 6 unidades con eficiencia técnica y 18 unidades ineficientes. Para cada una de estas últimas se identificó la unidad eficiente de referencia a la cual deberían imitar reduciendo entre un 2,55 y un 54,88% la cantidad de insumos y/o aumentando hasta un 204,3% la cantidad de productos. Conclusiones: el 47% de las UGL se desempeñan con ineficiencia técnica y de escala. Modificando la cantidad de insumos y/o aumentando la cantidad de productos podrían alcanzar la frontera de eficiencia. Sería recomendable explorar si factores tales como el tipo de contrato con los proveedores de servicios de salud o la densidad poblacional podrían estar causando tal ineficiencia.ficiencia.
Capacitação de profissionais de saúde da Estratégia Saúde da Família para execução das ações de alimentação e nutrição
Authors: Figueroa Pedraza Dixis , Silva dos Santos Eduarda Emanuela , De Oliveira Maria Mônica
Published: November 2021

Objetivou-se capacitar profissionais de saúde da Estratégia Saúde da Família para o desenvolvimento das ações de alimentação e nutrição, por meio de uma proposta de intervenção que consistiu em oficinas de diagnóstico, capacitação e avaliação. Para o diagnóstico, os profissionais responderam um questionário de avaliação de conhecimentos. Os resultados obtidos foram considerados para a organização das oficinas de capacitação, as quais foram avaliadas pelos profissionais usando um formulário padrão com diferentes itens de julgamento. Os achados incluíram, além de desconhecimento em relação a alguns aspectos básicos de nutrição, falta de conhecimento técnico dos profissionais de saúde para trabalhar as ações de alimentação e nutrição na atenção básica. Apesar de reconhecerem sua importância, os profissionais não visualizam as ações de nutrição nas perspectivas de vigilância, interdisciplinar e intersetorial. Na perspectiva da capacitação, as avaliações realizadas pelos profissionais foram positivas na maioria dos temas abordados e nos itens de julgamento.
Dimensiones para abordar la salud mental en el contexto de la migración. Revisión de literatura científica entre 2016 y 2019
Authors: Rubio León Diana Carolina
Published: November 2021

Introducción: Este artículo propone una revisión crítica de la categoría salud mental en relación con los retos que implican los procesos migratorios. Objetivo: revisar la literatura científica reciente sobre la articulación de las categorías de salud mental y migración. Método: fueron revisados 36 artículos científicos publicados entre 2016 y 2019. Las publicaciones fueron seleccionadas mediante un proceso sistemático de búsqueda de literatura científica en las bases de datos Pubmed, Ebsco, Science Direct y Scielo. Se realizó un análisis cualitativo para caracterizar e identificar tendencias y particularidades en la investigación. Resultados: la salud mental es abordada a partir de problemas, síntomas y enfermedades mentales. Los artículos son eminentemente cuantitativos y propios del área de la salud. Estos fueron realizados en países de altos ingresos que son receptores de personas migrantes en situación de vulnerabilidad. Se observan efectos diferenciales entre las situaciones previas a la migración y las posteriores, así como entre hombres y mujeres migrantes. Otros artículos hacen énfasis en las afectaciones particulares en la niñez y la adolescencia, o en el rol de los determinantes sociales en la migración. Discusión y conclusiones: el fenómeno migratorio amerita una revisión crítica de la categoría de salud mental centrada exclusivamente en los problemas y trastornos mentales. Es importante promover también una comprensión positiva de la salud mental en las intervenciones con la población migrante.
Experiencias de la misión médica en Colombia. Voces en medio del conflicto armado
Authors: Garcés Palacio Isabel Cristina , Ramos Sara milena , Quiceno Toro Natalia , García Jímenez Marlly Andrea , Ochoa Sierra María , Bedoya Bedoya Edison , Ruiz Sánchez Laura Estefany
Published: November 2021

Objetivo: describir la experiencia de la misión médica en el marco del conflicto armado en dos municipios colombianos. Métodos: investigación cualitativa con enfoque de estudio de caso comparativo a través de 22 entrevistas y 3 grupos focales. Para el tratamiento de la información se utilizaron técnicas del análisis de contenido. Resultados: en el marco del conflicto, en especial por las restricciones de movilidad, se presentaron dificultades para la prestación y el acceso a los servicios de salud, y el acceso a medicamentos. Se reportaron transgresiones a la Misión Médica como infracciones contra la vida y la infraestructura, y violaciones al secreto profesional. Se recomienda durante el post-acuerdo mejorar las condiciones laborales y la formación del personal de salud, incluyendo la capacitación en derecho internacional humanitario. Conclusión: el conflicto armado afectó en forma sustancial al personal de salud y la prestación del servicio.
Factores asociados a la dependencia funcional del adulto mayor de acuerdo con el modelo biopsicosocial. Estudio transversal realizado en 2017 en la capital de Veracruz, México
Authors: Popoca Betancourt Maribel , Cinta Loaiza Dulce María
Published: November 2021

Objetivo: explorar la asociación entre los factores biopsicosociales y la Dependencia Funcional (DF) en los Adultos Mayores (AM), que acuden al Instituto Nacional de las Personas Adultas Mayores (INAPAM). Metodología: se recolectó información respecto a las características sociodemográficas, clínicas, ambientales y personales de los pacientes. Además, se aplicó el Cuestionario para la Evaluación de la Discapacidad (WHODAS 2.0) en una muestra de 250 AM, del 20 de septiembre al 30 de noviembre del 2017. Resultados: la prevalencia general de la DF fue del 66.4%. El análisis bivariado mostró asociación para el sexo femenino RM:1.8 (IC95%:1.08-3), la categoría “sin pareja” del estado civil RM:1.9 (IC95%:1.1-3.3), la autopercepción negativa del estado de salud RM:2.8 (IC95%:1.6-4.8), la ausencia de facilitadores RM:2.6 (IC95%:1.4-5.1), la presencia de barreras RM:3.4 (IC95%:1.8-6.7) y el no asistir a consultas médicas RM:0.5 (IC95%:0.3-0.8). Conclusiones: este estudio profundiza en el conocimiento de los factores biopsicosociales de la DF, mostrando de manera sintética las interacciones biológicas, sociales y personales asociadas a esta. Además, el estudio contribuye a la generación de datos a partir de un lenguaje común en aspectos del funcionamiento.
Rehabilitación desde la economía política crítica: un debate necesario
Authors: Méndez Castillo Jaime Alberto
Published: November 2021

En este artículo se muestran las relaciones entre la configuración del pensamiento moderno, la idea de “hombre máquina”, y la rehabilitación como campo profesional reciente. La economía política crítica describe cómo esta perspectiva surge de las relaciones entre modernidad y capitalismo desde el siglo XIX. Más recientemente, esta tradición se articula con la del “complejo médico industrial” en el marco del “capitalismo cognitivo” que se ha venido consolidando en los últimos 40 años. Comprender estas relaciones permite pensar en alternativas para reorientar la rehabilitación hacia la realización de la vida desde las diferencias, los derechos humanos, los territorios y el buen vivir de los sujetos en sus colectividades.
Control Co-Design of Lithium-Ion Batteries for Enhanced Fast-Charging and Cycle Life Performances
Authors: Cui Tonghui , Zheng Zhuoyuan , Wang Pingfeng
Published: November 2021

As enablers of electric vehicles, lithium-ion batteries are drawing much attention for their high energy density and low self-discharge. However, “range anxiety” has remained a significant hindrance to its further development. As an alternative to increasing capacity, fast charging seems a reasonable solution. However, challenges remain due to the conflict between high charging rate and excessive capacity loss. In the past, enormous efforts have been carried out to resolve the dispute between high charging rates and large capacity losses by either improving the battery design or optimizing the charging/discharging protocols. In contrast, this study proposes a novel control co-design framework with adaptive surrogate modeling to address the challenges and to generate the systematic optimal battery design and the corresponding charging protocol simultaneously. The proposed method is ideal for lithium-ion battery systems to offer the improved performances as compared with traditional sequential optimization approaches due to the integration of strong coupling effects between electrode design and control optimization. The integrated adaptive surrogate modeling technique allows model reduction for efficient optimal control and simulation solutions. Meanwhile, it preserves an accurate mapping from the first-principle model to the reduced-order model. A hybrid model like this captures the multiscale nature of the cell, that is, micro-scale parameters affect the macro-scale behavior. It reduces the computational cost significantly. The battery co-design problem is formulated as a nested problem, where the inner-loop solves an open-loop optimal control problem and the outer-loop optimizes the plant design variables. The results show that system-level optimal design can be obtained for minimized charging time at various levels of health requirement.
Automated and Adaptive Geometry Preparation for AR/VR-Applications
Authors: Dammann Maximilian Peter , Steger Wolfgang , Stelzer Ralph
Published: November 2021

Product visualization in AR/VR applications requires a largely manual process of data preparation. Previous publications focus on error-free triangulation or transformation of product structure data and display attributes for AR/VR applications. This paper focuses on the preparation of the required geometry data. In this context, a significant reduction in effort can be achieved through automation.

The steps of geometry preparation are identified and examined with respect to their automation potential. In addition, possible couplings of sub-steps are discussed. Based on these explanations, a structure for the geometry preparation process is proposed.

With this structured preparation process it becomes possible to consider the available computing power of the target platform during the geometry preparation. The number of objects to be rendered, the tessellation quality and the level of detail can be controlled by the automated choice of transformation parameters.

We present a software tool in which partial steps of the automatic preparation are already implemented. After an analysis of the product structure of a CAD file, the transformation is executed for each component. Functions implemented so far allow, for example, the selection of assemblies and parts based on filter options, the transformation of geometries in batch mode, the removal of certain details and the creation of UV maps. Flexibility, transformation quality and time savings are described and discussed.
High Precision Contact Model for Ball Bearings With Waviness
Authors: Jeannot Camille , Sadoulet-Reboul E. , Dufrenoy S.
Published: November 2021

Studying high precision ball bearings requires the development of predictive models. In presence of waviness on the rings, geometrical and also mechanical parameters will vary according to the angular position. To consider these modifications, a nonlinear contact model is proposed with normal and tangential forces calculation using Hertz and Dahl’s models. To solve the static equilibrium of the bearing, a highly modular energy method is developed. It allows the determination of both local and global parameters using the same equation.

The 2D developed approach can be used to study different waviness orders and magnitudes to get a better understanding on how this affects the bearing behavior (contact load, balls gaping, pointing defects...). The presented results show that even small contact direction reorientation can create tangential forces. This modifies the bearing deflections and induces a residual moment. These phenomena can only be observed when the contact is accurately modeled.
Auxetic Structures Based on Rhombic Tiling
Authors: Warisaya Kanata , Hamanaka Hiroaki , Tokolo Asao , Tachi Tomohiro
Published: November 2021

Auxetic material using corner-connected kinematic tiles has been applied to different kinematic designs. However, existing works rely on the connectivity of regular polygonal tilings because of the overconstraining nature of kinematic tiling. This study proposes a new family of auxetic structures based on non-regular and aperiodic rhombic tiling inspired by the Tokyo 2020 Emblems. We convert emblem-like patterns on rhombic tilings into kinematic structures by regarding the rectangular figure as voids and the region between rectangles as rigid bodies. Due to the geometric properties of rhombic tiling, the structure forms a one-degree-of-freedom planar mechanism with a constant Poisson’s ratio of −1. The large combinatorial family of rhombic tilings provides design variations of kinematic structures with non-regular topology. Furthermore, we show a kirigami-based method for fabricating the structure as a compliant mechanism. This connection between math and art potentially broadens the range of architected materials based on folding, kirigami, and tessellation.
Linear Stability Analysis of a Waveboard Multibody Model With a Minimal Set of Equations
Authors: Agúndez A. G. , García-Vallejo D. , Freire E. , Mikkola A. M.
Published: November 2021

In this paper, the stability of a waveboard, the skateboard consisting in two articulated platforms, coupled by a torsion bar and supported of two caster wheels, is analysed. The waveboard presents an interesting propelling mechanism, since the rider can achieve a forward motion by means of an oscillatory lateral motion of the platforms. The system is described using a multibody model with holonomic and nonholonomic constraints. To perform the stability analysis, the nonlinear equations of motion are linearized with respect to the forward upright motion with constant speed. The linearization is carried out resorting to a novel numerical linearization procedure, recently validated with a well-acknowledged bicycle benchmark, which allows the maximum possible reduction of the linearized equations of motion of multibody systems with holonomic and nonholonomic constraints. The approach allows the expression of the Jacobian matrix in terms of the main design parameters of the multibody system under study. This paper illustrates the use of this linearization approach with a complex multibody system as the waveboard. Furthermore, a sensitivity analysis of the eigenvalues considering different scenarios is performed, and the influence of the forward speed, the casters’ inclination angle and the tori aspect ratios of the toroidal wheels on the stability of the system is analysed.
Tristable Properties in Electrostatically Actuated Initially Curved Coupled Micro Beams
Authors: Medina Lior , Seshia Ashwin A.
Published: November 2021

A limit point behaviour analysis of a metastructure, composed of two double clamped, initially curved beams, coupled via a rigid truss at their respective centres, is carried out when subjected to a distributed electrostatic load. The analysis is based on a reduced order (RO) model resulting from Galerkin’s decomposition, with symmetric buckling modes taken as the base functions, for either beam. All solutions employed the implicit arc-length “Riks” method to accommodate for winding equilibrium paths, while validation of the said results were carried out against finite differences (FD) direct solutions. In addition, local stability analysis via the energy method, conducted on the primary beam was instrumental in clarifying the role of the various extremum points by characterising which branches are stable, and which are not. The combined analysis has shown that the driving beam, which directly encounters the load, is able to possess bistable as well as tristable properties, provided that the metastructure meets certain geometrical parameters. Several variations of tristability are disclosed in the study. The analysis indicates that a model with at least three degrees of freedom (DOF) is needed to predict such configurations, as well as the various critical thresholds, with reasonable errors of around one percent when compared against FD. In so doing, the model can be used to provide static characterisation of the structure.
Design of a New Piezoelectrically Actuated Compliant Microgripper With High Area Usage Efficiency
Authors: Lyu Zekui , Xu Qingsong
Published: November 2021

Microgripper acts as an end-effector in the microassembly system, which completes pick-transport-release actions during the assembly process. Usually, the working space of the microassembly robot is small, and the operating environment is complicated. In addition, the assembled micro-objects are light, thin, brittle, and prone to damage. Thus, the microgripper should be able to provide a compact construction, a suitable clamping range, and safe clamping force for microassembly use. This paper presents the design, modeling, optimization, and simulation of a new piezoelectrically actuated compliant microgripper for microassembly application. The designed clamp has the advantages of large motion displacement and high area usage efficiency. A three-stage amplification mechanism based on bridge-type mechanism and leverage mechanism arranged in series is introduced to achieve a large jaw displacement. The optimization based on response surface analysis has been applied to determine the structural parameters of the amplification mechanism. The displacement amplification ratio of the microgripper is analyzed via the pseudo-rigid-body model approach. Finite element analysis is conducted to evaluate and validate the performance of the gripper. The simulation results indicate that the gripper can achieve a maximum gripping displacement of 545.12 μm with an area usage efficiency of 370.32 nm/mm2, which is better than available designs in the literature.
An Analytic Condition for the Finite Degree-of-Freedom of Linkages and Its Computational Evaluation
Authors: Müller Andreas
Published: November 2021

The finite degree of freedom (DOF) of a mechanism is determined by the number of independent loop constraints. In this paper a method is introduced to determine the maximal number of loop closure constraints (which is independent of a specific configuration) of multi-loop linkages and is applied to calculate the finite DOF. It rests on an algebraic condition on the joint screws and the corresponding computational algorithm to determine the maximal rank of the constraint Jacobian in an arbitrary (possibly singular) reference configuration, making use of the analytic condition that minors of certain rank and their higher derivatives vanish. Unlike the Lie group methods for estimation the DOF of so-called exceptional linkages, this method does not rely on partitioning kinematic loops into partial kinematic chains, and it is applicable to multi-loop linkages. The DOF computed with this method is at least as accurate as the DOF computed with the Lie group methods. It gives the correct DOF for any (possibly overconstrained) linkage where the constraint Jacobian has maximal rank in regular configurations. The so determined maximal rank has further significance for classifying linkages as being exceptional or paradoxical, but also for detecting singularities and shaky linkages.
Enhanced Multiple Surface Properties of Biometallic Materials by Laser Microprocessing
Authors: Wang Bing , Zhang Jiaru , Guan Yingchun
Published: November 2021

Metallic materials have been widely used owing to their good mechanical property and high flexibility. However, there are certain limitations for practical applications such as low anti-bacterial, cell adhesion, surface wettability and corrosion resistance property. In this paper, laser microprocessing of titanium (Ti) alloy and magnesium (Mg) alloy has been conducted, respectively. The cell adhesion of Ti6Al4V alloy and Mg-Gd-Ca alloy after laser microprocessing has been investigated. The results show that MC3T3-E1 cells have been successfully adhered to the treated surface and optical density are significantly increased due to hybrid micro/nano structure. Anti-bacterial test shows that the anti-bacterial rates against E. coli of laser-treated surface was up to 72%. Meanwhile, water contact angle has been increased from 57.4° to 135.3° indicating the changing of surface wettability from hydrophilic to hydrophobic. Moreover, corrosion test of Mg-Gd-Ca alloy has been conducted, which has been significantly improved after laser microprocessing. The present work showed that laser surface microprocessing could be a promising technique for fabricating different biomedical property surfaces.
Design of a Triple Crossed Flexure Pivot With Minimized Parasitic Shift
Authors: Thalmann E. , Henein S.
Published: November 2021

Thanks to their absence of play, absence of contact friction and possible monolithic fabrication, flexure pivots offer advantages over traditional bearings in small-scale, high accuracy applications and environments where lubrication and wear debris are proscribed. However, they typically present a so-called parasitic center shift that deteriorates their rotational guidance accuracy. Existing solutions addressing this issue have the drawbacks of reducing angular stroke, prohibiting planar design, or introducing overconstraints or underconstraints. This article introduces a new triple crossed flexure pivot called TRIVOT that has a reduced parasitic shift without overconstraints nor internal mobility while allowing either optimal stress distribution in the flexures or a planar design. The new architecture also makes it possible to place the center of rotation outside of the physical structure, which is not the case with traditional bearings. Based on finite element simulations, we show that the parasitic shift is reduced by one order of magnitude in comparison to the widely used crossed flexure pivot. We also derive and validate formulas for the rotational stiffness and angular stroke limit of the TRIVOT for given dimensions and material, which are valuable for its dimensioning towards practical applications. We expect this new pivot to become a competitive alternative to the crossed flexure pivot for applications where high accuracy and compactness are required.
Reliability-Informed Economic and Energy Evaluation for Design for Remanufacturing: A Case Study on a Hydraulic Manifold
Authors: Nemani Venkat P. , Liu Jinqiang , Ahmed Navaid , Cartwright Adam , Kremer Gül E. , Hu Chao
Published: November 2021

Design for Remanufacturing (DfRem) is an attractive approach for sustainable product development. Evaluation of DfRem strategies, from both economic and environmental perspectives, at an early design stage can allow the designers to make informed decisions when choosing the best design option. Studying the long-term implications of a particular design scenario requires quantifying the benefits of remanufacturing for multiple life cycles while considering the reliability of the product. In addition to comparing designs on a one-to-one basis, we find that including reliability provides a different insight into comparing design strategies. We present a reliability-informed cost and energy analysis framework that accounts for product reliability for multiple remanufacturing cycles within a certain warranty policy. The variation of reuse rate over successive remanufacturing cycles is formulated using a branched power-law model which provides probabilistic scenarios of reusing or replacing with new units. To demonstrate the utility of this framework, we use the case study of a hydraulic manifold, which is a component of a transmission used in some agricultural equipment, and use real-world field reliability data to quantify the transmission’s reliability. Three design improvement changes are proposed for the manifold and we quantify the costs and energy consumption associated with each of the design changes for multiple remanufacturing cycles.
Predicting the Material Removal Rate in Chemical Mechanical Planarization Process: A Hypergraph Neural Network-Based Approach
Authors: Xia Liqiao , Zheng Pai , Liu Chao
Published: November 2021

Material removal rate (MRR) plays a critical role in the operation of chemical mechanical planarization (CMP) process in the semiconductor industry. To date, many physics-based and data-driven approaches have been proposed to predict the MRR. Nevertheless, most of the existing methodologies neglect the potential source of its well-organized and underlying equipment structure containing interaction mechanisms among different components. To address its limitation, this paper proposes a novel hypergraph neural network-based approach for predicting the MRR in CMP. Two main scientific contributions are presented in this work: 1) establishing a generic modeling technique to construct the complex equipment knowledge graph with a hypergraph form base on the comprehensive understanding and analysis of equipment structure and mechanism, and 2) proposing a novel prediction method by combining the Recurrent Neural Network based model and the Hypergraph Neural Network to learn the complex data correlation and high-order representation base on the Spatio-temporal equipment hypergraph. To validate the proposed approach, a case study is conducted based on an open-source dataset. The experimental results prove that the proposed model can capture the hidden data correlation effectively. It is also envisioned that the proposed approach has great potentials to be applied in other similar smart manufacturing scenarios.
A Compliant Micromechanism for Biaxially Stretching Biological Cells
Authors: Fartyal Neeraj Singh , Marwah Himanshu , Balakrishnan Sreenath
Published: November 2021

Biological cells are known to respond to mechanical forces. Diverse biological phenomena such as tissue development and cancer are regulated by mechanical forces acting on cells. One such mechanical loading found in various tissues such as alveoli, pericardium, blood vessels, and urinary bladder is biaxial stretching. To study the effect of such a loading pattern, it is necessary to develop mechanical tools that can apply controlled biaxial stretching on cells. Here we present the design for such a device, a compliant micromechanism for biaxially stretching single cells.

We first designed a compliant, double-input, biaxial stretching mechanism based on re-entrant structures. Various stretch ratios, defined as the ratio between deformations in orthogonal directions, could be obtained by changing the dimensions of this mechanism. Next, we derived an analytical expression relating the geometric parameters to the stretch ratio. This analytical expression was verified using finite element analysis. By numerically solving this expression, multiple designs for a desired stretch ratio were obtained. Furthermore, we converted our design into a single-input mechanism by coupling the double-input biaxial stretcher to a single-input gripper mechanism. Finally, we demonstrate the functioning of our design using a macroscale, 3D-printed version.
Data-Driven Design-by-Analogy: State of the Art
Authors: Jiang Shuo , Hu Jie , Luo Jianxi
Published: November 2021

Design-by-Analogy (DbA) is a design methodology that draws inspiration from a source domain to a target domain to generate new solutions to problems or designs, which can benefit designers in mitigating design fixation and improving design ideation outcomes. Recently, the increasingly available design databases and rapidly advancing data science and artificial intelligence technologies have presented new opportunities for developing data-driven methods and tools for DbA support. Herein, we survey the prior data-driven DbA studies and categorize and analyze individual study according to the data, methods and applications in four categories including analogy encoding, retrieval, mapping, and evaluation. Based on such structured literature analysis, this paper elucidates the state of the art of data-driven DbA research to date and benchmarks it with the frontier of data science and AI research to identify promising research opportunities and directions for the field.
Periodic Temperature Responses in a Thermal System Under a Periodic Heating
Authors: Yu Bo , Luo Albert C. J.
Published: November 2021

In this paper, the periodic temperature responses of a thermal system under a periodic heating input are studied. Using the implicit mapping method, periodic temperature responses varying with excitation frequency are predicted for different input amplitudes. The corresponding stability of the periodic responses are discussed through eigenvalue analysis. The experimental and numerical results of the periodic response are presented for comparison to the analytical results.
Segmentation of Additive Manufacturing Defects Using U-Net
Authors: Wong Vivian Wen Hui , Ferguson Max , Law Kincho H. , Lee Yung-Tsun Tina , Witherell Paul
Published: November 2021

Additive manufacturing (AM) provides design flexibility and allows rapid fabrications of parts with complex geometries. The presence of internal defects, however, can lead to deficit performance of the fabricated part. X-ray Computed Tomography (XCT) is a non-destructive inspection technique often used for AM parts. Although defects within AM specimens can be identified and segmented by manually thresholding the XCT images, the process can be tedious and inefficient, and the segmentation results can be ambiguous. The variation in the shapes and appearances of defects also poses difficulty in accurately segmenting defects. This paper describes an automatic defect segmentation method using U-Net based deep convolutional neural network (CNN) architectures. Several models of U-Net variants are trained and validated on an AM XCT image dataset containing pores and cracks, achieving a best mean intersection over union (IOU) value of 0.993. Performance of various U-Net models is compared and analyzed. Specific to AM porosity segmentation with XCT images, several techniques in data augmentation and model development are introduced. This work demonstrates that, using XCT images, U-Net can be effectively applied for automatic segmentation of AM porosity with high accuracy. The method can potentially help improve quality control of AM parts in an industry setting.
Global Sensitivity Analysis for Field Response Based on the Manifold of Feature Covariance Matrix
Authors: Song Zhouzhou , Liu Zhao , Xu Can , Zhu Ping
Published: November 2021

In real-world applications, it is commonplace that the computational models have field responses, i.e., the temporal or spatial fields. It has become a critical task to develop global sensitivity analysis (GSA) methods to measure the effect of each input variable on the full-field. In this paper, a new sensitivity analysis method based on the manifold of feature covariance matrix (FCM) is developed for quantifying the impact of input variables on the field response. The method firstly performs feature extraction on the field response to obtain a low-dimensional FCM. An adaptive feature selection method is proposed to avoid the FCM from singularity. Thereby, the field response is represented by a FCM, which lies on a symmetric positive-definite matrix manifold. Then, the GSA technique based on the Cramér-von Mises distance for output valued on the Riemannian manifold is introduced for estimating the sensitivity indices for field response. An example of a temporal field and an example of a 2-D displacement field are introduced to demonstrate the applicability of the proposed method in estimating global sensitivity indices for field solution. Results show that the proposed method can distinguish the important input variables correctly and can yield robust index values. Besides, the proposed method can be implemented for GSA for field responses of different dimensionalities.
Evaluation of Inertial Measurement Units for Short Time Motion Tracking
Authors: Neurauter Rene , Hergel Peter , Gerstmayr Johannes
Published: November 2021

The goal of the present paper is to investigate inertial measurement systems for the ability to reconstruct the short time rigid body motion of objects, e.g. clumps in snow avalanches. While strapdown inertial navigation is well established, special algorithms are needed for the accurate motion reconstruction for short time motion with partially known boundary conditions. Furthermore, low cost inertial sensors are available with the ability to log translational accelerations and angular velocities as well as magnetic flux densities, which need to be extended with respect to GPS, time synchronization, and power management functionalities. In this paper, a newly developed system to measure the motion inside snow avalanches with redundant sensors, which have significantly higher measurement ranges than systems published in the past, is presented. In addition, an algorithm for motion reconstruction from measured translational accelerations, angular velocities and magnetic flux densities is derived. Furthermore, an optimization by eliminating terminal translational velocities is presented. The developed system is tested and its function is confirmed by reproducible measurement data from two experiments on skis, whereas these experiments differ in the magnitude of rotations. The presented motion reconstruction algorithm was used to evaluate the measurement data and thus the newly developed measurement system.
POD-Based Model Order Reduction for Tire-Soil Interaction Simulations
Authors: Sullivan Christopher C. , Yamashita Hiroki , Sugiyama Hiroyuki
Published: November 2021

The objective of this study is to develop model order reduction capabilities for high-fidelity off-road mobility simulations. The model reduction technique using the proper orthogonal decomposition (POD) is implemented at the level of the numerical solver in order to decrease the number of equations that need to be solved at each iteration of the solution procedure. The POD is, however, limited in that the modes are dependent on snapshot data collected during the running of a full order model (FOM), limiting the modes to being accurate only for the specific scenario from which they were collected. Due to this limitation, a method of mode adaptation through interpolation on a tangent space of the Grassmann manifold is investigated to allow modes to be predicted for cases in which a full order model has not been run. Modes produced for known values of a simulation parameter are used to predict the modes for a value of the simulation parameter for which POD modes have not been directly produced. For a single tire soil bin mobility model, the POD modes are found to be effective at retaining accuracy with minimal errors while also reducing computational time.
Design and Path Planning of Autonomous Solar Lawn Mower
Authors: Hazem Souhail , Mostafa Mohamed , Mohamed Ehab , Hesham Mohamed , Mohamed Abdelrahman , Lotfy Eyad , Mahmoud Ayman , Yacoub Mostafa
Published: November 2021

Current conventional lawn mowers have the following drawbacks; high initial costs, increasing engine noise levels, high operating costs due to high fuel consumption rates, the need to implement perimeter wires across the desired lawn mowing field, and high exhaustion of the operator in the long operating time. Hence, the need for a system that can achieve the same cutting effect of the existing lawn mowers with little or no operator’s fatigue, minimized noise pollution and running cost has risen. In present work, design of an autonomous solar lawn mower, a robotic vehicle that cut grass automatically with little human intervention, is discussed. The robotic vehicle is powered by Lithium-Ion batteries and depend on solar power delivered from a solar base station for charging the batteries. The mechanical design of the vehicle is flexible with the ability to control the height of the vehicle during grass mowing. Differential steering, with the implementation of multiple sensors is presented for obstacle avoidance. Also, a Raspberry Pi microcontroller for the image processing application through a camera is used for path planning. Furthermore, a solar based station structure is designed for charging the robotic vehicle batteries with minimized running cost, utilization of renewable energy source, no health hazards, not having any effect on the environment, and human’s effort and time are saved.
In-Situ Observation Selection for Quality Management in Metal Additive Manufacturing
Authors: Roh Byeong-Min , Kumara Soundar R. T. , Yang Hui , Simpson Timothy W. , Witherell Paul , Lu Yan
Published: November 2021

Metal additive manufacturing (MAM) provides a larger design space with accompanying manufacturability than traditional manufacturing. Recently, much research has focused on simulating the MAM process with regards to part geometry, porosity, and microstructure properties. Despite continued advances, MAM processes have many variables that are not well understood with respect to their effect on the part quality. With the common use of in-situ sensors — such as CMOS cameras and infrared cameras — numerous, real-time datasets can be captured and analyzed for monitoring both the process and the part.

However, currently, real-time data predominantly focuses on the build failure and process anomalies by capturing the printing defects (cracks/peel-off). A large amount of data — such as melt pool geometries and temperature gradients — are just beginning to be explored, along with their connections to final part quality. Towards investigating these connections, in this paper we propose models that capture numerous sensor capabilities and associate them with the corresponding, real-time, physical phenomena. These sensor models lay the foundation for a comprehensive, knowledge framework that forms the basis for quality monitoring and management of MAM process outcomes.

Using our previously developed process ontology model [1–3], which describes the relationship between process variables and process outcomes, we can discover the relationship between the real-time, physical phenomena and the deviations in the targeted, build quality. For example, statistically significant sensor data that predicts deviations from targeted process qualities can be detected and used to control the process parameters. Case studies that scope the physical phenomena and sensor data are provided for verifying the effectiveness and efficiency of the proposed qualification and certification models.
A Novel Micro-Positioning Stage With Large-Stroke and Adjustable Stiffness
Authors: Yang Zhijun , Cai Bingyu , Li Ruiqi , Peng Hao , Bai Youdun
Published: November 2021

The existing micro-motion stage based on flexure hinge can hardly meet the requirements of a high-precision stage with large stroke and variable operating conditions (especially variable frequency operation). In this paper, a flexible hinge micro-motion stage with adjustable stiffness is presented. A wide range of stiffness and frequency adjustments are realized by changing the length of the flexure hinge through the movement of the support. However, the change on the stiffness of the flexure hinge is non-linear when is in large deformation. It is difficult to use the traditional PID algorithm to control such nonlinear system without the complete mathematical model, and much more complicated control strategies are required to deal with the condition of large deformation of the flexure hinge. In this paper, the active disturbance rejection control (ADRC) strategy is adopted to solve the above non-linear control problem without relying on the complete system model. A novel model-compensated ADRC based on the dynamic characteristics is proposed to further improve the performance of the micro-motion stage. Experiments show that the ADRC with model compensation (MADRC) can achieve high positioning and tracking precision faster than the conventional ADRC. The presented micro-motion stage based on stiffness-adjustable flexure hinges and MADRC design is capable to meet the industrial application requirements of large stroke or variable working conditions.
An Radio Frequency Impedance Matching Control Benchmark System for Advanced Control Strategies Evaluation
Authors: Rodríguez Carlos A. , Viola Jairo , Chen YangQuan
Published: November 2021

An impedance matching network is mandatory between the source and the load to obtain the maximum power transfer in a system. For example, in the plasma processing technology widely used in semiconductor wafer processing, guaranteeing the maximum transference of power is the main goal. This paper presents the problem definition and guidelines for a radio-frequency (RF) impedance matching benchmark. This benchmark system we developed in public domain is useful in studying and evaluating various impedance patching algorithms fairly. The goal is to match the impedance of the source with its complex conjugate of the load in a minimum time. The reflection coefficient is used as an evaluation metric to measure the reflected power, which has to be zero to guarantee the maximum power transfer. Some impedance matching controllers proposed in the literature are tested as sample applications on this benchmark in a fair manner to check and evaluate its robustness and stability performance against different initial conditions, load conditions and perturbations on the impedance matching network control system. We also suggested a novel Feedforward Control (FF) profile generation method with a primitive sample feedback control strategy (proportional-integral (PI) controller) as a baseline reference for the benchmark.
Analytical Study of Dry Whip Phenomena During Rotor-Stator Rub
Authors: Srivastava Aman K. , Kumar Anurag , Tiwari Mayank , Singh Akhilendra
Published: November 2021

Rotor-Stator Rub is a rare but catastrophic phenomenon and in most cases leads to failure of Gas Turbine Engines. Asynchronous rub namely Partial Rub and Dry whip are two of the most common observed rub related phenomena. Dry whip leads to pure backward whirl and instability. This paper studies the dry whirl analytically to determine the boundaries of instability and establish expressions for nonlinear vibrations in case of dry whip. First, Nonlinear Natural Frequency has been defined for a rotor-stator rub system and expression for natural motion of the system has been formulated. Next, Pure rolling of rotor on stator has been used as a condition to approximate the nonlinear system to find out the dependence of dry whip frequency on the parameters such as stiffness, damping ratio, coefficient of friction and spin speed of the rotor. Moreover, a validation of the obtained frequencies and amplitudes obtained analytically has been performed through the simulation of rotor stator rub system using RK-4 integration technique. Furthermore, this study offers insight into the frequencies that are present in the Radial motion of the rotor and its source of origin. The radial displacement of the rotor has harmonics which are the result of interaction between the rotor speed and the backward whirl frequency causing dry whip.