bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-Robot Path Planning for Cooperative 3D Printing
Authors: Elagandula Saivipulteja , Poudel Laxmi , Sha Zhenghui , Zhou Wenchao
Published: January 2021

Cooperative 3D printing (C3DP) is an emerging technology that employs multiple mobile 3D printers to work together on printing the desired part cooperatively for better scalability and more flexibility. In our previous work, we developed a chunker, a geometric partition tool, to divide a part into smaller chunks and a computational framework to automatically generate schedules for collision-free printing. However, the framework can only generate print schedules for one print job. To schedule multiple robots to print multiple jobs, job assignment and path planning for robots to move between jobs also needs to be considered. In this paper, we apply the previously developed framework to generate print schedules for multiple jobs concurrently, and then developed a new approach to combine the independent print schedules with two heuristic methods: 1) Job by Job heuristics and 2) Row by Row heuristics. Once a single schedule is generated using one of the two heuristics, the conflict-based search algorithm is used to find the optimal path for robots to move from one print location to next. A case study is conducted where three different jobs are concurrently scheduled on a floor with four available printing robots. The results validate the utility of the proposed approach in generating viable print schedules with collision-free path planning.
Production of Medium-Scale Metal Additive Geometry With Hybrid Manufacturing Technology
Authors: Saleeby Kyle S. , Kurfess Tom , Feldhausen Tom , Love Lonnie
Published: January 2021

Oak Ridge National Lab’s (ORNL) Metal Big Area Additive Manufacturing (mBAAM) and Hybrid Manufacturing teams in the Manufacturing Demonstration Facility (MDF) was tasked with developing a part that exceeded 24 inches in length and 100lbs in weight on a laser hotwire welding system. The Mazak VC-500A/5X AM HWD hybrid 5-axis CNC laser hotwire system was leveraged to complete the task. The proposed geometry was manufactured with 410 stainless steel on AISI1018 steel substrate in just over 36 hours of build time. The proposed geometry was sliced and additively manufactured in three segments; the base, and two extrusions measuring 10 inches in length and 14 inches in length. Production of this component demonstrated hybrid capabilities requiring fixed 5-axis rotations to complete geometry that exceeded the defined build volume of the machine. Multiple repairs of the part were conducted in-situ leveraging the additive and subtractive capabilities of the Mazak hybrid system. Significant overbuilding challenges were encountered and manually addressed by leveraging subtractive capabilities of the hybrid system. Future processes are presented for development to reduce overheating of top layers. Final part measurements exceeded 107 lbs. in weight and 24.5 inches in length along the principal axis; the largest and heaviest part created by a hybrid system at the MDF.
Computational Study of Solvent Based Extrusion 3D Printing
Authors: Rath Usharani , Pandey Pulak Mohan
Published: January 2021

In the present work, authors have performed a finite element modelling and simulation of the solvent based extrusion 3D printing process. The present work can be considered as a pioneering work as there is no available literature on the modelling aspects of the solvent based extrusion 3D printing process. Two physics interfaces of a commercially available multiphysics modelling tool, such as computational fluid dynamics, and heat transfer along with a mathematical approach such as the Arbitrary Lagrangian-Eulerian method were integrated to simulate the aforementioned 3D printing process. The physical model consisted of a homogenous solution of polycaprolactone polymer and a volatile solvent namely methylene chloride. A two dimensional axisymmetric model was formulated to simulate the flow behaviour and evaporation behaviour of the polymer solution from the nozzle inlet to the platform on which the solution gets deposited. The velocity and temperature field of the polymer solution during the printing of one layer is analyzed. Furthermore, the evaporation mechanism followed by evaporative cooling of the deposited layer is also illustrated. It was observed that the flow velocity obtained was 16 mm/s at the nozzle exit for a feed rate of 40 mm/min at the nozzle inlet. The evaporative cooling of the Methylene chloride solvent resulted in the reduction in temperature with an evaporation rate of 1.74 g/m3s.
Digital Thread Enabled Manufacturing Automation Towards Mass Personalization
Authors: Ramesh Akhilnandh , Qin Zhaojun , Lu Yuqian
Published: January 2021

Manufacturing industries are moving towards mass personalization, which refers to the rapid production of individualized products, with large scale efficiencies. This shift from push-type mass customization to pull-type mass personalization will pose critical operational challenges to manufacturing businesses, with complexities ranging from effective requirements elicitation to design, manufacturing, commissioning and after-sales support. Aiming at addressing these challenges, a feasible operational framework for enabling efficient manufacturing automation for mass personalization is proposed in this paper. A key element of this operational framework is the Digital Thread, which streamlines information flow associated with design, manufacturing, maintenance and servicing of a personalized product, each of which are represented as Digital Twins. An As-Designed Digital Twin is created from the beginning of the product co-design process, which then evolves into the subsequent design and manufacturing process and systems resulting in As-Designed Digital Twin evolving to As-Planned Digital Twin and then to As-Built Digital Twin. The personalized product, after it’s commissioning and installation constitutes the As-Maintained Digital Twin of the product, which stores product data related to field performance. The data exchange and communications between these Digital Twins that reside in the various departments of the organization and the management systems create a seamless Digital Thread, capturing the lifecycle information of each personalized product. Personalized product is proposed to be developed through a self-organizing shopfloor, working on a multi-agent mechanism and controlled by a central agent control algorithm, which can coordinate and provide individualized process plans. The Digital Twins, interlinked by a Digital Thread and realized by a self-organizing shopfloor, thus result in increased level of automated control in engineering and manufacturing. To validate the feasibility of this proposed framework, we tested the information flow in the Digital Thread with a case study in the construction industry. Finally the challenges faced by such an automation framework and the area of future work are also discussed.
DEM As a Tool for Optimizing Powder Metallurgy Processes
Authors: Bobba Dhanooj , Tabei Seyed A. , Pando Miguel , Cherukuri Harish P.
Published: January 2021

Powder metallurgy processes such as cold and hot isostatic pressing and powder-bed fusion additive manufacturing are being extensively used to produce metallic and ceramic parts due to several significant benefits these techniques provide, including reduction in wasted material, more precise handling of complicated shapes and requirement of fewer steps to achieve the final geometry and tolerance. Often the quality of the products obtained through these processes is greatly affected by the homogeneity of the feedstock powders used. But the presence of particles of different shapes and sizes in the powders may lead to inhomogeneous distribution which give rise to segregation of particles. In this study, discrete element method was used to investigate the degrees of segregation of a binary mixture in a cylindrical die with sharp stepped features. To study the effect of the composition of the binary mixture, three different mass ratios are considered in the study. In addition, vibrations are applied to the cylindrical die to increase the compaction of the particles in the stepped regions of the die. The effects of vibration amplitude and vibration frequency on the size segregation of the particles in the die are studied. At higher amplitude location dependent segregation patterns were observed.
Robot-to-Robot Collaboration for Fixtureless Assembly: Challenges and Opportunities in the Automotive Industry
Authors: Saez Miguel , Spicer Patrick
Published: January 2021

This paper summarizes the latest developments in robot-to-robot collaboration for fixtureless assembly. In addition, some of the technology challenges and potential applications in the automotive industry are described. Fixtureless assembly systems have been developed to increase the flexibility of body shop systems. These systems eliminate the need for using dedicated fixtures to set the geometry of body assemblies. A key technology enabler for a fixtureless assembly process is robot-to-robot collaboration based on perception and advanced control solutions. In a fixtureless assembly process, robots move and hold parts together in the geometry setting pose for assembly instead of using fixtures. In this paper the technology requirements and performance results of a production-relevant demonstration cell are presented. Moreover, the technology and performance requirements to use the fixtureless approach in other automotive assembly applications are reviewed. Results show that dimensional performance from the newly developed fixtureless process was acceptable and within the tolerance range. Initial cost estimate show that a fixtureless process offers a significant cost benefit over a conventional assembly process, especially for a multi-style production line or when new styles are frequently introduced.
Online Quality Monitoring of Plastic Parts Using Real-Time Data From an Injection Molding Machine
Authors: Loftis Jonathan , Farahani Saeed , Pilla Srikanth
Published: January 2021

Every day-increasing connectivity and access to data can provide valuable insight to the plastics industry. While the amount of accessible data has been increasing, the means to process and store it efficiently while squeezing valuable process information out of it has not been prioritized. The increase in connectivity has led to much of this data being stored and used in cloud computing systems which can be both monetarily and computationally expensive. Motivated by this fact, the feasibility of using real-time data directly captured from injection molding machine is investigated in terms of their capabilities for online quality monitoring. Using the built-in sensors that are usually existed in the standard injection molding machines (barrel pressure, screw position, and clamp force) and a dimensional reduction method, models are derived to predict quality of injection molded parts (Weight, Thickness, and Diameter). The developed models show high predictive capability with R2 values ranging from 0.89–0.97. Moreover, the combination of the proposed feature extraction method and implementation of Partial Least Squares Regression (PLS) demonstrates that most of the computing for automatic quality control can be done on local edge computing hardware with a significantly summarized data, and only control commands need to be sent through the cloud.
Powder Thermal Conductivity Measurements in L-PBF Using Powder-Included Build Specimens: Internal Geometry Effect
Authors: Zhang Shanshan , Lane Brandon , Chou Kevin
Published: January 2021

This study investigates the thermal conductivity of 17-4PH stainless steel powder that was encapsulated within specimens with different internal geometries in laser powder bed fusion (L-PBF) additive manufacturing (AM). The objective is to evaluate the effect of the internal geometry of the specimens on the measurement of the powder thermal conductivity and to compare the thermal properties amongst the 17-4PH and two additional powder materials used in L-PBF. Continued from the previous work [1], three new cone configurations in the hollow specimens were designed and fabricated in an L-PBF system. The thermal conductivity of the internal powder was indirectly measured using an experimental-numerical approach, combined with laser-flash testing, finite element (FE) heat transfer modeling and multivariate inverse method. The results reveal that the thermal conductivity of 17-4PH powder ranges from 0.67 W/(m·K) to 1.34 W/(m·K) at 100 °C to 500 °C, and varies with the internal geometry of the specimens. In addition, the measurement of the hollow specimen with a convex cone seems to be a more reliable evaluation. Further, the thermal conductivity ratio of the powder to the solid counterpart of 17-4PH approximately ranges from 3.9 % to 5.5 % at tested temperatures, which is similar to the results obtained from the nickel-based super alloy 625 (IN625) and Ti-6Al-4V (Ti64) powders measured in a previous study.
The Environmental Impacts of Metal Powder Bed Additive Manufacturing
Authors: Liao Jiankan , Cooper Daniel R.
Published: January 2021

Additive manufacturing (AM) is widely recognized as a critical pillar of advanced manufacturing and is moving from the design shop to the factory floor. As AM processes become more popular, it is paramount that engineers and policymakers understand and then reduce their environmental impacts. This article structures the current work on the environmental impacts of metal powder bed processes: selective laser melting (SLM), direct metal laser sintering (DMLS), electron beam melting (EBM), and binder jetting (BJ). We review the potential benefits and pitfalls of AM in each phase of a part’s lifecycle and in different application domains (e.g., remanufacturing, hybrid manufacturing etc.). We highlight critical uncertainties and future research directions throughout.

The environmental impacts of AM are sensitive to the specific production and use-phase context; however, several broad lessons can be extracted from the literature. Unlike in conventional manufacturing, powder bed production impacts are dominated by the generation of the direct energy (electricity) required to operate the AM machines. Combined with a more energy-intensive feedstock (metal powder) this means that powder bed production impacts are higher than in conventional manufacturing unless production volumes are very small (saving tool production impacts) and/or there are significant material savings through part light weighting or improved buy-to-fly ratios.
Experimental Investigation of Effects of Needle Diameter on Algae Cell Growth in Green Bioprinting
Authors: Thakare Ketan , Jerpseth Laura , Qin Hongmin , Pei Zhijian
Published: January 2021

Bioprinting can fabricate structures based on layer-by-layer deposition of biomaterials. Bioprinting of animal cells shows great promise for tissue regeneration and tissue research. Plant cells can also be used when synthesizing bioink. Bioprinting with bioink that has been synthesized with plant cells instead of animal cells is called green bioprinting. Green bioprinting offers greater spatial control over the growth of plant matter by immobilizing cells. It is known that certain variables affect the growth and propagation (cellular reproduction) of cells in green bioprinted constructs post bioprinting. These variables include accessibility to components required for photosynthesis, such as nutrients, moisture and light. However, multiple parameters can also vary during the extrusion of bioink in the bioprinting process, including extrusion pressure, extrusion temperature, needle diameter, and printing speed. This paper reports a study to examine the effects of needle diameter during bioprinting on the growth of Chlamydomonas reinhardtii algae cells in green bioprinted constructs. Growth of Chlamydomonas reinhardtii algae cells was quantified by measuring cell count. The constructs were bioprinted with needle diameters of 22 gauge, 25 gauge, and 27 gauge. It was found that decreasing needle diameter was correlated with decreased cell count on the second and fifth days post bioprinting. Furthermore, the magnitude of cell count increase between the second and the fifth days post bioprinting decreased with decreasing needle diameter. Future research is needed to examine the effects of other printing parameters on cell growth.
Multi-Objective Optimization of Wire Electrical Discharge Machined Ultra-Thin Silicon Wafers Using Response Surface Methodology for Solar Cell Applications
Authors: Rana Pinal , Bhartiya Divyanshu , Annebushan Singh Meinam , Marla Deepak
Published: January 2021

Recent investigations on the fabrication of ultra-thin silicon (Si) wafers using wire-electrical discharge machining (wire-EDM) were observed to possess some inherent limitations. This includes severe thermal damage, kerf-loss, and low slicing rate, which could be detrimental towards realizing actual practical applications. The extent of thermal damage, kerf-loss, and slicing rate largely depends on the process parameters such as open voltage (OV), servo voltage (SV), and pulse on-time (Ton). Therefore, choosing the optimal parameters that pertain to minimum thermal damage and kerf-loss while maintaining a higher slicing rate is the key to further excel in the fabrication of Si wafers using wire-EDM. Therefore, the present study is an effort to analyze and identify the optimal parameters that relate to the most effective Si slicing in wire-EDM. A central composite design (CCD) based response surface methodology (RSM) was used for optimizing the process parameters. The capability to slice Si wafers in wire-EDM was observed to be highly influenced by the discharge energy, which had a positive impact on the overall responses. The severity of thermal damages was observed to be mainly dominated by the variation in open voltage and Ton due to the high diffusion of thermal energy into the workpiece, which led to intense melting and subsequent re-solidification. The parametric optimization resulted in OV = 84.32 V, SV = 42.98 V and Ton = 0.62 μs as the most feasible parameter that relates to comparatively high slicing rate (0.65 mm/min), low kerf-loss (280 μm) and thermal damage (18 μm) for a given machine. In general, with a decrease in spark energy slicing rate and thermal damage decreases whereas, kerf-loss increases. When spark energy decreases by 83%, there is a nearly 55% decrease in slicing rate and thermal damage and a 10% increase in kerf-loss.
Multi-Extrusion Additive Manufacturing for Error Compensation: A Demonstrative Case Study
Authors: Kan Chen , Ye Zehao , Yang Yiran , Di Lei , Shah Deep , Shah Dhairya
Published: January 2021

The global additive manufacturing industry has been rapidly increasing, owing to its unique layer-by-layer production method. While additive manufacturing has superior capabilities compared to traditional subtractive manufacturing, limitations still exist, which significantly hinder the larger-scale implementations of additive manufacturing. Some challenging issues include unsatisfactory dimensional accuracy, surface quality, etc. In the literature, extensive research efforts have dedicated to detecting, predicting, and compensating process errors using various methodologies. In this work, a new approach is proposed for error compensation using multi-extrusion additive manufacturing process. Three demonstrative case studies are conducted, i.e., multicolor and/or multimaterial printing, geometric error compensation, and rough surface compensation. Experimental results have shown that the proposed approach is effective in utilizing the multi-nozzle capability in additive manufacturing quality control. Notably, the proposed approach has remarkable potentials to be extended for in-situ error compensation. Our future forays will focus on integrating the proposed approach with in-situ process monitoring approaches for layer-wise defection and compensation of process anomalies.
Laser Engineered Net Shaping of Graphene Oxide Reinforced Titanium: Effects of Reinforcement and Laser Power
Authors: Li Yunze , Zhang Dongzhe , Wang Hui , Hu Yingbin , Cong Weilong
Published: January 2021

Titanium is widely used in many industry areas (such as automotive industry, aerospace industry, and medical industry) due to its superior properties of low density, high strength to weight ratio, strong corrosion-resistance, etc. However, commercial pure titanium (CP-Ti) parts still have some disadvantages (such as relatively low hardness, and wear resistance) which limit their further applications. In order to reduce these disadvantages, some reinforcement materials (such as ceramics and nanomaterials) are involved to fabricate titanium-based parts Compared with ceramics, low content of nanomaterials could significantly improve the mechanical properties and reduce disadvantages of ceramics (such as poor wettability and low interfacial bonding between reinforcement materials and Ti). Graphene oxide (GO) is a preferable candidate of nanomaterial due to its excellent mechanical properties and low density. The GO reinforced Ti parts have been fabricated by the selective laser sintering (SLS) process. Laser additive manufacturing (LAM) process includes directed energy deposition method and powder bed fusion method. Compared with powder bed fusion method (such as the SLS and selective laser melting (SLM)), directed energy deposition method (e.g. laser engineered net shaping (LENS)) has advantages of parts repairing and gradient parts fabrication capabilities. There are no studies on the fabrication of GO-Ti parts by LENS process. In this study, GO-Ti parts are fabricated by the LENS process. The effects of GO and laser power on fabricating defects of porosity, microstructure, and mechanical properties (including microhardness, elastic modulus, wear rate) were studied, for the first time.
Design and Manufacturing of Lattice Structure Using Extrusion-Based Additive Manufacturing
Authors: Alam Adeeb , Shovon Abu , Ahsan Nazmul , Habib Ahasan , Khoda Bashir
Published: January 2021

Cellular solids have diverse potential applications such as mechanical, thermal, phononic, and biological applications. However, the fabrication of cellular structure with the 3D printing process is often infeasible due to the anisotropies, fabrication imperfections, and for that, a significant amount of resources is required. In this paper, we have analyzed the preprocessing knowledge base of extrusion-based 3d printing and contemplated it with post-processing performance measurement for lattice structure printing. We considered cuboid cell type micro and macro lattice structures for our analysis. To compare cuboid with truss, a single unit cell is printed, and its compressive strength is measured. Three different patterns (traditional micro infill, interlocked macro assembly, traditional macro strut) are designed and fabricated to investigate the effects of design strategy and mechanical performance. We have found anisotropic behavior in the fabricated structure as expected in traditional print. However, interlocked assembly based cuboid structure has demonstrated uniformity for both inplane and out of plane load. Furthermore, we have found that the applied load type has a bigger impact on the performance of the printed structure and should be considered during their preprocessing stage.
Controlling Peeling Front Geometry in a Roll-to-Roll Thin Film Transfer Process
Authors: Zhao Qishen , Hong Nan , Chen Dongmei , Li Wei
Published: January 2021

Mechanical peeling is becoming an important manufacturing process in areas such as transfer printing and two-dimensional (2D) materials fabrication. Existing research has demonstrated the potential of successful peeling in small-scale by hand or with a robotic system. However, to scale up the manufacturing process, a roll-to-roll continuous system is needed. It is generally understood that the peeling front characteristics, including peeling angles, speed, and tension, are critical to the quality of the peeling process. In a roll-to-roll setting, controlling these characteristics becomes challenging since there are fewer degrees of freedom in the control design, and the complex relationship among the process parameters. In this study, a system model of a roll-to-roll peeling process is developed and a feedback controller to maintain the desired system performance is proposed. The control method is demonstrated with both numerical simulation and experimental results. It is shown that with the proposed control scheme, desired peeling front geometry can be achieved.
Spatiotemporal Fusion Network for the Droplet Behavior Recognition in Inkjet Printing
Authors: Huang Jida , Wang Tianjiao , Segura Luis Javier , Joshi Gayatri Shirish , Sun Hongyue , Zhou Chi
Published: January 2021

Inkjet 3D printing has broad applications in areas such as health and energy due to its capability to precisely deposit micro-droplets of multi-functional materials. However, the droplet of the inkjet printing has different jetting behaviors including drop initiation, thinning, necking, pinching and flying, and they are vulnerable to disturbance from vibration, material inhomogeneity, etc. Such issues make it challenging to yield a consistent printing process and a defect-free final product with desired properties. Therefore, timely recognition of the droplet behavior is critical for inkjet printing quality assessment. In-situ video monitoring of the printing process paves a way for such recognition. In this paper, a novel feature identification framework is presented to recognize the spatiotemporal feature of in-situ monitoring videos for inkjet printing. Specifically, a spatiotemporal fusion network is used for droplet printing behavior classification. The categories are based on inkjet printability, which is related to both the static features (ligament, satellite, and meniscus) and dynamic features (ligament thinning, droplet pinch off, meniscus oscillation). For the recorded droplet jetting video data, two streams of networks, the frames sampled from video in spatial domain (associated with static features) and the optical flow in temporal domain (associated with dynamic features), are fused in different ways to recognize the droplet evolving behavior. Experiments results show that the proposed fusion network can recognize the droplet jetting behavior in the complex printing process and identify its printability with learned knowledge, which can ultimately enable the real-time inkjet printing quality control and further provide guidance to design optimal parameter settings for the inkjet printing process.
Accuracy Analysis of the Micro Machine Tool With Co-Planar Driving Mechanism
Authors: Wang Shih-Ming , Ye Zhe-Zhi , Gunawan Hariyanto
Published: January 2021

Due to the manufacturing requirement of miniaturized high-tech products, micro machining with micro a micro machine tool has been regarded as an important technology. The main goal of this study is to build up the key technologies, such as optimal design, synchronously-driving control, accuracy optimization analysis for a low-cost and high-accuracy micro machine tool with a multi-DOF platform with co-plane synchronously-driving mechanism. Due to the advantages of the mechanism, the machine will be able to have high resolution and high accuracy without use of expensive drive components and high-end CNC controller. Because of no pile-up structure, the machine has less kinematic inertia effect, and has the merits of light weight, high stiffness, low cutter of gravity, and more stable. Furthermore, the machine has more DOF which gives better cutting performance than a 3-DOF machine tool. The research items include static/dynamic stiffness optimization, synchronously driving controls, hybrid error analysis. Kinematics analysis and volumetric error model will be derived and analyzed. The prototype of the designed micro machine tool was built, and the accuracy of machine was tested. The accuracy calibration results showed the machine can reach a positioning accuracy of 800nm.
Supplemental Material: Apatite nanoparticles in 3.46–2.46 Ga iron formations: Evidence for phosphorus-rich hydrothermal plumes on early Earth
Authors: Rasmussen Birger , al. et
Published: January 2021

Figures S1 and S2, and Tables S1–S3.
Supplemental Material: Is the Eastern Denali fault still active?
Authors: Choi Minhee , Eaton David W. , al. et
Published: January 2021

Catalog of relocated seismicity, table of moment tensor parameters, detailed methodology of the velocity model, hierarchical clustering, moment tensors, stress inversion, Coulomb stress calculation, and Figures S1–S12.
Supplemental Material: High-precision U-Pb age constraints on the Permian floral turnovers, paleoclimate change, and tectonics of the North China block
Authors: Wu Qiong , Shen Shu-zhong , al. et
Published: January 2021

Stratigraphy of the study sections, previous geochronology, U-Pb analytical procedures, age results, and Bayesian age modeling.
Material point method (MPM) hydro-mechanical modelling of flows impacting rigid walls
Authors: Cuomo Sabatino , Perna Angela Di , Martinelli Mario
Published: January 2021

The study on impact mechanisms of flow-like landslides against structures is still an open issue in the scientific literature. Many researchers have so far employed either experiments or numerical methods, but the evaluation of the impact forces on mitigation obstacles remains difficult especially if the solid–fluid interaction within the flow is considered. This study shows how advanced numerical tools, such as material point method, may be used in simulating those complex processes. The simulations are carried out for two well-documented laboratory tests: a dry granular flow impacting a rigid wall under different geometries and testing conditions in a small-scaled flume and a saturated flow with complex propagation pattern in a centrifuge apparatus. The numerical modelling is validated against the observations and then used to explore the response of different flows impacting rigid structures in other conditions than in the experiments. The soil–fluid interaction influences the type of impact mechanism, the kinematics of the flow, and the space–time trend of the impact pressure against the structure.
Unraveling the hidden organisation of urban systems and their mobility flows
Authors: Gallotti Riccardo , Bertagnolli Giulia , De Domenico Manlio
Published: January 2021

Increasing evidence suggests that cities are complex systems, with structural and dynamical features responsible for a broad spectrum of emerging phenomena. Here we use a unique data set of human flows and couple it with information on the underlying street network to study, simultaneously, the structural and functional organisation of 10 world megacities. We quantify the efficiency of flow exchange between areas of a city in terms of integration and segregation using well defined measures. Results reveal unexpected complex patterns that shed new light on urban organisation. Large cities tend to be more segregated and less integrated, while their overall topological organisation resembles that of small world networks. At the same time, the heterogeneity of flows distribution might act as a catalyst for further integrating a city. Our analysis unravels how human behaviour influences, and is influenced by, the urban environment, suggesting quantitative indicators to control integration and segregation of human flows that can be used, among others, for restriction policies to adopt during emergencies and, as an interesting byproduct, allows us to characterise functional (dis)similarities of different metropolitan areas, countries, and cultures.
α β-Relations and the Actual Meaning of α-Renaming
Authors: Basaldella Michele
Published: January 2021

In this work we provide an alternative, and equivalent, formulation of the concept of λ-theory without introducing the notion of substitution and the sets of all, free and bound variables occurring in a term. We call α β-relations our alternative versions of λ-theories. We also clarify the actual role of α-renaming in the lambda calculus: it expresses a property of extensionality for a certain class of terms. To motivate the necessity of α-renaming, we construct an unusual denotational model of the lambda calculus that validates all structural and beta conditions but not α-renaming. The article also has a survey character.
A Study on the Creep Characteristics of Airport Viscous Subsoil Based on Unsaturated Stress Level
Authors: Feng Jun , Ma Yue , Liu Zaobao
Published: January 2021

The present study takes the ratio of the matric suction to the net vertical stress and the ratio of the matric suction to the net mean stress as new unsaturated stress levelsfandF, respectively. Based on the laboratory tests and theoretical derivation, the modified one-dimensional Mesri creep model and three-dimensional creep model were established, which takes the unsaturated stress level into account. Then, the one-dimensional and three-dimensional creep characteristics of the unsaturated viscous subsoil of an airport under different unsaturated stress levels were analyzed. The following conclusions could be drawn: (1) under different stress levels, the one-dimensional creep deformation of unsaturated soil has a power function relationship with time, and the change rate exponentially decreases with the stress level, which can be well-expressed by the proposed modified one-dimensional Mesri creep model; (2) under different stress levels, the three-dimensional creep strain of the unsaturated soil shows a hyperbolic curve with time and a near-linear relationship at the semilogarithmic coordinate, which can be well-expressed by the proposed modified three-dimensional creep model; (3) under different stress levels, both the one-dimensional creep and three-dimensional creep of the unsaturated soil can be divided into two stages, which are the accelerated creep stage and stable creep stage.
Investigation on Mechanical Properties of GH4720Li at High Strain Rates at Wider Temperature Range
Authors: Chen Jie , Zhang Haifeng , Zhang Yunlong , Zhang Hongtao , Yang Qingxiang , Ye Longhai
Published: January 2021

In this paper, the dynamic mechanical properties of GH4720Li nickel-base alloy under a large temperature range and high and low strain rates were studied by the hot compression test. The difference of mechanical properties of GH4720Li alloy under high and low strain rates was analyzed from the perspective of microstructure. The hot compression test experimental results showed that the true stress of GH4720Li alloy decreased at a low strain rate as the trial temperature elevated. Nevertheless, it was abnormal that the true stress increased at high strain rate condition as temperature elevated. By comparing the microstructure under high and low strain rates, it was found that the precipitates under low strain conditions contained a large amount of Cr (Mo). However, the content of Cr (Mo) in the precipitates at a high strain rate decreased, while the content of Fe increased. It would be concluded that Cr (Mo) would reduce the compressive strength and plasticity of GH4720Li alloy, while Fe would increase the compressive strength and plasticity of GH4720Li alloy. In addition, under the condition of a low strain rate, the shape of Cr (Mo) precipitates obtained at 20°C was lamellar, but it was spherical at 800°C. The compressive strength of GH4720Li composites with lamellar precipitates was higher than that of spherical precipitates.
Changes in Diffuse Optical Tomography Images During Early Stages of Neoadjuvant Chemotherapy Correlate with Tumor Response in Different Breast Cancer Subtypes
Authors: Altoe Mirella L. , Kalinsky Kevin , Marone Alessandro , Kim Hyun K. , Guo Hua , Hibshoosh Hanina , Tejada Mariella , Crew Katherine D. , Accordino Melissa K. , Trivedi Meghna S. , Hershman Dawn L. , Hielscher Andreas H.
Published: January 2021

Purpose:

This study's primary objective was to evaluate the changes in optically derived parameters acquired with a diffuse optical tomography breast imaging system (DOTBIS) in the tumor volume of patients with breast carcinoma receiving neoadjuvant chemotherapy (NAC).

Experimental Design:

In this analysis of 105 patients with stage II–III breast cancer, normalized mean values of total hemoglobin (ctTH{b_N}$), oxyhemoglobin (ct{O_2}H{b_N}$), deoxy-hemoglobin concentration (ctHH{b_N}$), water, and oxygen saturation (St{O_2}_N$) percentages were collected at different timepoints during NAC and compared with baseline measurements. This report compared changes in these optical biomarkers measured in patients who did not achieve a pathologic complete response (non-pCR) and those with a pCR. Differences regarding molecular subtypes were included for hormone receptor–positive and HER2-negative, HER2-positive, and triple-negative breast cancer.

Results:

At baseline, ctHH{b_N}$ was higher for pCR tumors (3.97 ± 2.29) compared with non-pCR tumors (3.00 ± 1.72; P = 0.031). At the earliest imaging point after starting therapy, the mean change of ctHH{b_N}$ compared with baseline ({\Delta _{TP1}}ctHH{b_N}$) was statistically significantly higher in non-pCR (1.23 ± 0.67) than in those with a pCR (0.87 ± 0.61; P < 0.0005), and significantly correlated to residual cancer burden classification (r = 0.448; P < 0.0005). {\Delta _{TP1}}ctHH{b_N}$ combined with HER2 status was proposed as a two-predictor logistic model, with AUC = 0.891; P < 0.0005; and 95% confidence interval, 0.812–0.969.

Conclusions:

This study demonstrates that DOTBIS measured features change over time according to tumor pCR status and may predict early in the NAC treatment course whether a patient is responding to NAC.
HAND1 and BARX1 Act as Transcriptional and Anatomic Determinants of Malignancy in Gastrointestinal Stromal Tumor
Authors: Hemming Matthew L. , Coy Shannon , Lin Jia-Ren , Andersen Jessica L. , Przybyl Joanna , Mazzola Emanuele , Abdelhamid Ahmed Amr H. , van de Rijn Matt , Sorger Peter K. , Armstrong Scott A. , Demetri George D. , Santagata Sandro
Published: January 2021

Purpose:

Gastrointestinal stromal tumor (GIST) arises from interstitial cells of Cajal (ICC) or their precursors, which are present throughout the gastrointestinal tract. Although gastric GIST is commonly indolent and small intestine GIST more aggressive, a molecular understanding of disease behavior would inform therapy decisions in GIST. Although a core transcription factor (TF) network is conserved across GIST, accessory TFs HAND1 and BARX1 are expressed in a disease state-specific pattern. Here, we characterize two divergent transcriptional programs maintained by HAND1 and BARX1, and evaluate their association with clinical outcomes.

Experimental Design:

We evaluated RNA sequencing and TF chromatin immunoprecipitation with sequencing in GIST samples and cultured cells for transcriptional programs associated with HAND1 and BARX1. Multiplexed tissue-based cyclic immunofluorescence and IHC evaluated tissue- and cell-level expression of TFs and their association with clinical factors.

Results:

We show that HAND1 is expressed in aggressive GIST, modulating KIT and core TF expression and supporting proliferative cellular programs. In contrast, BARX1 is expressed in indolent and micro-GISTs. HAND1 and BARX1 expression were superior predictors of relapse-free survival, as compared with standard risk stratification, and they predict progression-free survival on imatinib. Reflecting the developmental origins of accessory TF programs, HAND1 was expressed solely in small intestine ICCs, whereas BARX1 expression was restricted to gastric ICCs.

Conclusions:

Our results define anatomic and transcriptional determinants of GIST and molecular origins of clinical phenotypes. Assessment of HAND1 and BARX1 expression in GIST may provide prognostic information and improve clinical decisions on the administration of adjuvant therapy.
Association between Caregiver Neurotic Personality Trait and Elder Abuse: Investigating the Moderating Role of Change in the Level of Caregiver Perceived Burden
Authors: Fang Boye , Yan Elsie , Yang Xiaozhao , Pei Yaolin
Published: January 2021

Objectives: To investigate whether caregiver neuroticism affects the level of elder abuse and whether changes of caregiver perceived burden alter this relationship. Methods: Using 2-year longitudinal data, a consecutive sample of 800 Chinese family caregivers and their care recipients with dementia were recruited from the geriatric and neurological departments of 3 grade-A hospitals in the People’s Republic of China. All the participatory dyads were assessed between September 2015 and February 2016 and followed up for 2 years. Results: Significant increase in the prevalence was found for physical abuse, psychological abuse, and caregiver neglect. Caregiver neuroticism was associated with an increased level of physical and psychological abuse over the 2-year observation period; however, change in the level of caregiver perceived burden altered this association. Specifically, the absence and decrease of perceived care burden prevented an increase in the level of physical and psychological abuse among caregivers high in neuroticism. Although caregiver neuroticism was also associated with an increased level of caregiver neglect, caregiver perceived burden did not appear to have an impact on this relationship. Discussion: This study provided evidence that caregiver neuroticism was associated with an increased level of physical and psychological abuse, while changes in the level of caregiver perceived burden may alter this trajectory. These findings suggest the importance of implementing caregiver-centered intervention and prevention programs for elder abuse by specifically targeting caregivers’ behaviors related to their neurotic personality trait and cognitive appraisal of caregiving stressors associated with such personality traits.
Two Damascus Document Fragments and Mistaken Identities
Authors: Tigchelaar Eibert
Published: January 2021

Two of the unidentified Cave 4 fragments preserving text of the Damascus Document which were mistakenly associated with 4Q269 should instead be assigned to 6Q15, since they join to 6Q15 fragment 1. This is the first case of a join between fragments claimed to have come from different caves. Also PAM 41.734 does not clearly distinguish between all Cave 4 and Cave 6 fragments.
A Farewell to the Hodayot of the Community
Authors: Newsom Carol A.
Published: January 2021

Since the 1960s, most scholars have distinguished between two types of compositions in the Hodayot, those that represent the persona of the Teacher of Righteousness and those that represent the spiritual experience of the Community in general. This theory, however, was developed before scholars had access to a reliable reconstruction of 1QHa or to the fragmentary manuscripts of the Hodayot from Cave 4. While that evidence largely confirms the distinctiveness of the group of compositions associated with the Teacher, which are clustered in cols. 10–17, the evidence undermines the cogency of a category of “Community” hodayot. The presence of lmśkyl headings in several compositions, claims to leadership by the speaker, the appearance of an expression that implicitly compares the speaker to Moses, and other factors make it more likely that the non-Teacher hodayot should be associated with the Maśkîl rather than with ordinary sectarians.
Some new and known species of Bomolochidae (Copepoda, Cyclopoida) parasitic on Japanese actinopterygian fishes, 2 — with the description of two new genera
Authors: Izawa Kunihiko
Published: January 2021

Five species of Bomolochidae parasitic on Japanese fishes are (re)described. They are Orbitacolax leptoscari Yamaguti, 1953, Paraorbitacolax sphyraenae gen. et sp. nov., Pseudoeucanthus rhabdosargi sp. nov., Pumiliopes scombri sp. nov., and Triceracolax pagri gen. et sp. nov.
Corporate Complicity in International Crimes through Arms Supplies despite National Authorisations?
Authors: Ambos Kai
Published: January 2021

I examine the criminal responsibility of companies for crimes committed with their exported weapons, even if that export was authorised by national authorities. Responsibility may rise directly from the national export control law and/or from (international) criminal law (icl) concerning (international) crimes committed. While (transnational) corporations have a due diligence obligation to prevent serious human rights violations, it is unclear how a national authorisation relates to this. Does it displace it, or is the authorisation overridden by the obligation? To better understand how a national authorisation procedure works, before analysing this issue from an icl perspective, I analyse German law regarding a recent case of weapons supply to Mexico. The situation under icl law is then examined regarding the Yemen complaint submitted to the International Criminal Court (icc). The article attempts some thoughts on dealing with this and similar cases, hoping to serve as a starting point for further debate.
Congregation(s) in Digital Culture
Authors: Mahan Jeffrey H.
Published: January 2021

This essay draws on a particular example of Christian community in the urban American West to ask how digital culture is shifting the way religious identity, community, and leadership are being performed in cultures shaped by digital communication. It suggests more attention is needed to the complexity of organized religion and to the ways religious communities respond to media change. Further, that scholars of media, religion, and culture can help practitioners better understand their media-context and strategize within it.
Rediscovery of Camellia langbianensis (Theaceae) in Vietnam
Authors: HOI QUACH VAN , DOUDKIN ROMAN V. , CUONG TRUONG QUANG , SON LE VAN , DUNG LUONG VAN , KIM SOO-YONG , Yang Shi-Xiong
Published: January 2021

Camellia langbianensis is a species endemic to southern Vietnam. It was described by Gagnepain based on the collection of Poilane and was rediscovered about 80 years since published. The complete descriptions and illustrations are provided for this species. A comment on the affinities with closely related species C. vidalii is also shown. It is accessed to be Critically Endangered (CR) according to IUCN categories and criteria.
Chalcogenia rejzeki sp. nov. from Kenya (Coleoptera: Buprestidae: Anthaxiini)
Authors: BÍLÝ SVATOPLUK
Published: January 2021

Chalcogenia rejzeki sp. nov. from Kenya is described, illustrated and compared with the most similar species, and attributed to the Chalcogenia sulcipennis species-group within the genus Chalcogenia Saunders 1871. Brief catalogue of the genus Chalcogenia with new country records is provided.
Long Non-Coding RNA-Colon Cancer Associated Transcript 1 Down-Regulation Inhibits Cell Proliferation and Promotes Apoptosis in Colorectal Cancer Through Enhancing miR-152 Expression
Authors: Li Jindong , Wang Xi , Huang Xin , Li Na , Ling Ya , Kong Min , Hua Huilian
Published: January 2021

Colorectal cancer is a common malignant cancer that is characterized by high mortality rate. CCAT1 is a type of newly discovered lncRNA. This research was conducted to study the role of CCAT1 in colorectal cancer. The findings showed that there was significant up-regulation of CCAT1
expression in colorectal cancer. Then, online bioinformatic database and dual-luciferase reporter assay to prove CCAT1 and miR-152 have direct binding sites. Many researches demonstrated that miR-152 played a crucial role in development of colorectal cancer. Therefore, we then explored the
relationship between CCAT1 and miR-152 in colorectal cancer. qRT-PCR analysis showed that miR-152 was lowly expressed in cancer tissue and cells. We then explored the effect of CCAT1 and miR-152 on the biological effects of colorectal cancer cells. MiR-152 up-regulation significantly reduced
colorectal cancer cell viability and enhanced apoptosis. Furthermore, CCAT1-shRNA inhibited colorectal cancer cell viability and enhanced cell apoptosis were significantly eliminated by miR-152 inhibitor. Combined with all results, CCAT1/miR-152 axis was related to colorectal cancer progression
regulation, which might be used as new therapeutic targets for colorectal cancer treatment.