bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the existence of critical compatible metrics on contact 3‐manifolds
Authors: Mitsumatsu Y. , Peralta‐Salas D. , Slobodeanu R. 
Published: November 2024

AbstractWe disprove the generalized Chern–Hamilton conjecture on the existence of critical compatible metrics on contact 3‐manifolds. More precisely, we show that a contact 3‐manifold admits a critical compatible metric for the Chern–Hamilton energy functional if and only if it is Sasakian or its associated Reeb flow is ‐conjugate to an algebraic Anosov flow modeled on . In particular, this yields a complete topological classification of compact 3‐manifolds that admit critical compatible metrics. As a corollary, we prove that no contact structure on admits a critical compatible metric and that critical compatible metrics can only occur when the contact structure is tight.
Equivariant algebraic concordance of strongly invertible knots
Authors: Di Prisa Alessio 
Published: November 2024

AbstractBy considering a particular type of invariant Seifert surfaces we define a homomorphism from the (topological) equivariant concordance group of directed strongly invertible knots to a new equivariant algebraic concordance group . We prove that lifts both Miller and Powell's equivariant algebraic concordance homomorphism (J. Lond. Math. Soc. (2023), no. 107, 2025‐2053) and Alfieri and Boyle's equivariant signature (Michigan Math. J. 1 (2023), no. 1, 1–17). Moreover, we provide a partial result on the isomorphism type of and obtain a new obstruction to equivariant sliceness, which can be viewed as an equivariant Fox–Milnor condition. We define new equivariant signatures and using these we obtain novel lower bounds on the equivariant slice genus. Finally, we show that can obstruct equivariant sliceness for knots with Alexander polynomial one.
The Use of Slack Variables in the Adjoint Method Handling Inequality Constraints in Optimal Control and the Application to Tumor Drug Dosage
Authors: Eichmeir Philipp , Nachbagauer Karin , Steiner Wolfgang 
Published: November 2024

Abstract
In this article, a modified gradient approach, based on the adjoint method, is introduced, to deal with optimal control problems involving inequality constraints. A common way to incorporate inequality constraints in the adjoint approach is to introduce additional penalty terms in the cost functional. However, this may distort the optimal control due to weighting factors required for these terms and raise serious concerns about the magnitude of the weighting factors. The method in this article avoids penalty functions and can be used for the iterative computation of optimal controls. In order to demonstrate the key idea, first, a static optimization problem in the Euclidean space is considered. Second, the presented approach is applied to the tumor anti-angiogenesis optimal control problem in medicine, which addresses an innovative cancer treatment approach that aims to inhibit the formation of the tumor blood supply. The tumor anti-angiogenesis optimal control problem with free final time involves inequality and final constraints for control and state variables and is solved by a modified adjoint gradient method introducing slack variables. It has to be emphasized that the novel formulation and the special use of slack variables in this article delivers high accurate solutions without distorting the optimal control.
Anand Model Constants of Sn–Ag–Cu Solders: What Do They Actually Mean?
Authors: Gharaibeh Mohammad A. , Pitarresi James M. 
Published: November 2024

Abstract
Finite element simulations are broadly utilized to calculate the thermally induced mechanical deformations of interconnecting solder materials in electronics. The Anand unified viscoplasticity model is a prevalent choice for simulating the mechanical responses of solder joints, comprising nine parameters whose individual effects are not fully addressed in the literature. For this reason, this study examines the influence of each Anand parameter on the mechanical response of leadless tin–silver–copper (SAC) solder alloys with varying silver content through comprehensive nonlinear finite element simulations. Anand model coefficients for different SAC alloys, including SAC105, SAC205, SAC305, and SAC405, were sourced from existing literature and used to establish a systematic study matrix for each parameter. These coefficients were then integrated into thermomechanical simulations to induce inelastic deformations in the solder interconnections. The response of the solder interconnects is analyzed in terms of equivalent inelastic strains and inelastic strain energy density. Results indicated that specific Anand parameters could skew the solder joint stress–strain response toward brittle behavior, while other parameters could lead to a more ductile response. Through statistical factorial analysis, the significance of each parameter is found to vary considerably, ranging from negligible to highly significant. The findings of this study are crucial for understanding the behavior of different SAC solder configurations and their expected thermal fatigue performance based on Anand creep constants. Furthermore, this paper provides foundational insights into the interpretation of Anand coefficients and their influence on the mechanical response of solder materials, a topic not yet explored in the existing literature.
On the Consistent Classification and Treatment of Uncertainties in Structural Health Monitoring Applications
Authors: Kamariotis Antonios , Vlachas Konstantinos , Ntertimanis Vasileios , Koune Ioannis , Cicirello Alice , Chatzi Eleni 
Published: November 2024

Abstract
In this paper, we provide a comprehensive definition and classification of various sources of uncertainty within the fields of structural dynamics, system identification, and structural health monitoring (SHM), with a primary focus on the latter. Utilizing the classical input–output system representation as a main contextual framework, we present a taxonomy of uncertainties, intended for consistent classification of uncertainties in SHM applications: (i) input uncertainty; (ii) model form uncertainty; (iii) model parameter/variable uncertainty; (iv) measurement uncertainty; and (v) inherent variability. We then critically review methods and algorithms that address these uncertainties in the context of key SHM tasks: system identification and model inference, model updating, accounting for environmental and operational variability (EOV), virtual sensing, damage identification, and prognostic health management. A benchmark shear frame model with hysteretic links is employed as a running example to illustrate the application of selected methods and algorithmic tools. Finally, we discuss open challenges and future research directions in uncertainty quantification for SHM.
A Graph Database Schema for Metal Additive Informatics
Authors: Allen Marshall D. , Arróyave Raymundo , Malak Richard 
Published: November 2024

Abstract
Metal additive manufacturing (AM) enables the creation of metal structures with complex materials and geometry for advanced performance capabilities. Metal AM continues to grow in popularity for use cases from alloy design to advanced manufacturing. In this work, we identify the requirements for a novel metal AM informatics schema based on the benefits and shortcomings of existing methods. After investigating different types of databases as the basis of our schema, including relational database management systems (RDBMS) and graph databases (GDBs), we identify the labeled property graph (LPG) configuration of GDBs as a solution due to its capabilities for dimensional scalability, data reusability & adaptability, topological representation, graph traversal queries, and property/label metadata storage. Then, we propose an LPG database schema that addresses the identified requirements for metal AM informatics for materials design. This approach closes the loop from materials development to manufacturing & characterization, enabling accelerated high-fidelity alloy design for metal AM applications. We discuss our implementation of the LPG database schema in Python and demonstrate the schema’s capabilities for visualization and exploration of the alloy design space. We then apply our LPG database schema by designing a compositionally graded alloy (CGA) part with real materials. Lastly, we discuss the possibilities for future work to expand upon the proposed schema.
Water Savings and User-Centered Validation of an Automatic Scheduling-Manual Operation (AS-MO) Irrigation Tool: A Case Study on a Jordanian Farm
Authors: Van de Zande Georgia D. , Sheline Carolyn , Pratt Shane , Winter Amos G. 
Published: November 2024

Abstract
This work aims to demonstrate that long-term use of an automatic scheduling-manual operation (AS-MO) irrigation tool increases water savings, compared to fully manual irrigation, a common practice on resource-constrained farms in the Middle East and North Africa (MENA). Prior work has shown that an AS-MO tool has the potential to bridge the gap between fully manual irrigation and existing precision agriculture solutions, but such a tool has not been demonstrated on a farm. Through an 11-week case study conducted on a Jordanian farm, we show that farmers use this tool as intended. To understand how the tool performs in context, a functional tool prototype was designed to deliver a long-term AS-MO user experience to study participants. The prototype monitored local weather conditions, generated water-efficient schedules using an existing scheduling theory, and notified users’ phones when they should manually open or close valves. The irrigation practices of participants using the AS-MO prototype were compared to conventional practices. Significant water savings were not realized, but participants demonstrated successful use of the tool. Irrigation events were measured to show that users correctly confirmed 93% of the scheduled events using the tool’s interface. Of the irrigation events that did occur, a majority of their durations fell within 15% of the scheduled durations. Results from this work and feedback from study participants can continue to improve the design of the proposed AS-MO tool. If adopted at scale, this tool could increase the adoption of water-efficient irrigation practices on resource-constrained farms that are not served by existing precision irrigation technology, improving food security and sustainable agriculture in MENA.
A Multi-Sized Unit Cell Design Method to Design Lattice Support Structures for Complex Geometries in LPBF
Authors: White Lisha , Zhang Guanglu , Seo Junwon , Lamprinakos Nicholas , Rollett Anthony , Cagan Jonathan , Zhang Yongjie Jessica 
Published: November 2024

Abstract
Composed of individual unit cells strategically arranged to achieve a desired function, lattices are a promising solution for laser powder bed fusion (LPBF) support structure design. Despite their many advantages (e.g., multifunctionality and reduced material cost), prior work in lattice support structure (LSS) design primarily focused on parts with horizontal support domains (e.g., cantilever beams) that are not translatable to complex domains, thereby limiting their application. This work introduces a multi-sized unit cell design optimization (MSO) method to create LSS for parts with complex surfaces. The proposed method utilizes voxelization to identify and sort the locations of box-like unit cells of different sizes. It also allows for efficient design optimization through a modified simulated annealing-based optimization algorithm. The effectiveness and efficiency of the MSO method are demonstrated through the case study of an adapter pipe for a high-temperature heat exchanger. For this demonstration, LSS using multi-sized unit cells are designed to increase heat transfer rate while considering structural integrity and material cost constraints. When the optimally-directed results derived from the MSO method are compared to benchmark designs of equal-sized unit cells, it achieves an average heat transfer rate that is 16% higher while satisfying volume, stress, and deformation constraints.
Exploring Ultrasonic Welding As a Means of Improving Structural Design Properties of FFF-Printed Thermoplastics
Authors: Goehring Luke , Fink Rainer , Tai Bruce , Patterson Albert E. 
Published: November 2024

Abstract
Additive manufacturing (AM) is a technology that has improved manufacturing capabilities in a huge variety of industries, as well as increasing rapid prototyping capabilities. Fused filament fabrication (FFF) is one of these technologies, that has seen use in both industry and lab-scale settings to print thermoplastics and polymer matrix composites that have a thermoplastic matrix. However, it suffers from a major flaw in that the strength of printed parts is anisotropic and uneven, creating difficulties when designing parts intended to bear a structural load or face forces from a variety of directions. This study attempts to improve this weakness by introducing an ultrasonic spot welding process to the normal FFF 3D printing method in order to improve the design space available for parts manufactured with this process. Two welding treatments are attempted following different patterns, one where there are overlapping welds to cover as much surface area as possible, and another with no overlapping welds to prevent the risk of damaging or over-welding the part. The samples, as tested by a modified version of ASTM D5528, showed drastically increased maximum fracture load, suggesting a much stronger level of interlayer adhesion. This improved structural property allows for increased design space and potential uses for FFF printed parts in a large variety of industrial and research settings.
DARTS-NETGAB: Design Automation and Real-Time Simulation Using Neural Networks Ensembles for Turbocompressors on Gas-Bearings
Authors: Massoudi Soheyl , Bejjani Joseph , Horvath Timothy , Üstun Dogukan , Schiffmann Jürg 
Published: November 2024

Abstract
In the domain of engineering design, where efficiency in simulation and precision in modeling are paramount, this study introduces DARTS-NETGAB, a pioneering platform uniquely designed for real-time simulation and automated design. Specifically tailored for gas-bearing supported turbocompressors, DARTS-NETGAB integrates neural network ensembles with a parametric CAD construction library to deliver unprecedented prediction speeds and modeling precision across various engineering systems. This integration allows for seamless, real-time performance evaluations of complex, multidisciplinary systems and automated CAD model generation. This framework streamlines the design process, reduces cycles times and enhances adaptability to manufacturing imperfection.
DARTS-NETGAB features a user-centric interface developed using the advanced Panel-Bokeh Python libraries, facilitating dynamic and interactive design modifications directly within a web browser. This capability enables immediate visualization and adjustment of a comprehensive turbocompressor model, thereby streamlining the transition from theoretical design to practical application.
The paper details how the combination of DARTS-NETGAB’s rapid, accurate predictive capabilities with its robust design tools not only advances micro-turbocompressor design but also revolutionizes engineering processes across diverse systems. By merging cutting-edge computational techniques with practical, user-friendly tools, DARTS-NETGAB offers a significant improvement over traditional methods, fostering more efficient and innovative engineering solutions.
CAD-Prompted Generative Models: A Pathway to Feasible and Novel Engineering Designs
Authors: Chong Leah , Rayan Jude , Dow Steven , Lykourentzou Ioanna , Ahmed Faez 
Published: November 2024

Abstract
Text-to-image generative models have increasingly been used to assist designers during concept generation in various creative domains, such as graphic design, user interface design, and fashion design. However, their applications in engineering design remain limited due to the models’ challenges in generating images of feasible designs concepts. To address this issue, this paper introduces a method that improves the design feasibility by prompting the generation with feasible CAD images. In this work, the usefulness of this method is investigated through a case study with a bike design task using an off-the-shelf text-to-image model, Stable Diffusion 2.1. A diverse set of bike designs are produced in seven different generation settings with varying CAD image prompting weights, and these designs are evaluated on their perceived feasibility and novelty. Results demonstrate that the CAD image prompting successfully helps text-to-image models like Stable Diffusion 2.1 create visibly more feasible design images. While a general tradeoff is observed between feasibility and novelty, when the prompting weight is kept low around 0.35, the design feasibility is significantly improved while its novelty remains on par with those generated by text prompts alone. The insights from this case study offer some guidelines for selecting the appropriate CAD image prompting weight for different stages of the engineering design process. When utilized effectively, our CAD image prompting method opens doors to a wider range of applications of text-to-image models in engineering design.
Fundamental Study on Practical Measurement Method of Anisotropic Thermal Conduction Performance Using Zig-Zag Jigs
Authors: Kimura Natsumi , Fukue Takashi , Yoshihiro Haruki , Hirasawa Koichi 
Published: November 2024

Abstract
This study describes a practical method of measuring anisotropic thermal conductivity using a combination of 1-dimensional steady thermal conductivity measurement and thermal conduction analysis. We tried to develop a practical measurement method of the thermal conductivity difference in a test piece between thickness and in-plane directions based on the 1-dimensional steady-state method. Using a paired cylindrical zig-zag jig with the teeth were arranged in alternate rows, generating the thermal conduction change. The test piece of the material was mounted between the teeth of the zig-zag jigs. K-type thermocouples were installed in each jig at each temperature measurement position, and the temperature gradient was measured to obtain the heat flux. The thermal resistance between the top and bottom jigs with the test piece, which was sandwiched by the jigs, was evaluated by the temperature gradient and supplied heat flux. Separately, the FEM analysis of thermal conduction in the test system was also performed.
In this measurement method, by the comparison of the thermal resistance between the experiment and the FEM analysis, the in-plane thermal conductivity was estimated. By the comparison of the thermal resistance through the zigs and the test piece between the experiment and the FEM analysis, the in-plane thermal conductivity was calculated. We used the proposed measurement method to evaluate the thermal conductivity of isotropic acrylic, soda grass, and several types of anisotropic PCB in the thickness and in-plane directions, respectively. For isotropic materials, the measurement result of both thickness and in-plane direction thermal conductivity showed good agreement with the nominal value. In the case of R1705, which is one of an anisotropic PCB, the difference was nearly twice as large in the thickness direction as in the in-plane direction. Due to fiber orientation, PCBs generally have thermal conductivity anisotropy between the thickness and in-plane directions. The thermal conductivity in the in-plane direction tends to be higher than in the thickness direction, and the measurement result confirmed this difference. In the range of the report, the measurement of the anisotropic thermal conductivity was successful, and the effectiveness of the proposed method was confirmed.
Comparing Wire Bonding Strategies for High Power Applications
Authors: Vinson Whit , Torres Frida , Huitink David 
Published: November 2024

Abstract
In this study, a control group of aluminum wire bonds is compared against a group of autocatalytically (electroless) nickel plated aluminum wire bonds in terms of fuse current and electromigration performance. Fuse current testing results demonstrated a negative relationship between wire length and fuse current density for both groups of bonds. Ambient temperature was also shown to reduce fuse current density for both groups. Fuse current density was shown to be lower for plated wires due to the increased conductive cross-sectional area. Electromigration experiments showed a significant lifetime reduction for plated bonds compared to the “bare” control group. The authors suspect that the elevated ambient temperature and joule-heating driven by the elevated current density in these tests caused a high-electrical-resistivity aluminum-nickel intermetallic to be created, causing a fuse failure under the same conditions that electromigration failure was seen in the control group. An analytical examination of the effects of nickel plating on sample electrical performance has been provided to discuss this suspicion. Future work should continue to be done to examine the impacts of interconnect alloy and surface modifications to qualify/disqualify them for use in high current density and temperature environments.
Parametric Thermal Design for Heterogeneously Integrated High-Power Packages
Authors: Im Yunhyeok , Kim Junyoung , Choi Mingeun , Bouzidi Myriam , Li Xingchen , Kim Joon Woo , Muslu Ahmet Mete , Kumar Satish , Swaminathan Madhavan , Sitaraman Suresh K. , Joshi Yogendra 
Published: November 2024

Abstract
As power densities increase in heterogeneously integrated systems, with the introduction of new 3D architectures and the increasing number of transistors on chips, there exists a continued bottleneck for thermal management. High temperatures have a drastic impact on memory performances and refresh cycles. Moreover, thermal coupling between neighboring chiplets on a package is increasing as the types of chips on a heterogeneously integrated package diversify, and this, in turn, creates different heat flux densities within a heterogeneously integrated package. Thus, there arises a need for the implementation of efficient thermal design and solutions that cater to high heat fluxes within a package as well as different heights for different chip stacks within a package. In this paper, we present a parametric thermal design of heterogeneously integrated packages for high-performance computing. We focus on a 2.5D packaging structure, which includes components including artificial intelligence (AI) accelerators and high bandwidth memory (HBM) on a silicon interposer. Analytically and numerically, we investigate the thermal challenges stemming from high power density in stacked dies, variations in die heights, and cooling limitations at the package surface. To mitigate temperature gradients within the package, we propose a thermal-aware package structure, emphasizing the inside architecture. Also, the thermal coupling effect is studied for multiple cooling technologies on the outer surface using a thermal violation region graph. This research has shown that not only the internal structure of the package but also its ability to transfer heat to the outer surface has a significant impact on the thermal coupling effect. Using our approach, we can design package architecture systematically considering the external cooling environment in the early design stage.