bluuebunny/crossref_metadata_2025 huggingface dataset:
A two level approach for simulating Bose–Einstein condensates by Localized Orthogonal Decomposition
Authors: Döding Christian , Henning Patrick , Wärnegård Johan
Published: May 2024

In this work, we consider the numerical computation of ground states and dynamics of single-component Bose–Einstein condensates (BECs). The corresponding models are spatially discretized with a multiscale finite element approach known as Localized Orthogonal Decomposition (LOD). Despite the outstanding approximation properties of such a discretization in the context of BECs, taking full advantage of it without creating severe computational bottlenecks can be tricky. In this paper, we therefore present two fully-discrete numerical approaches that are formulated in such a way that they take special account of the structure of the LOD spaces. One approach is devoted to the computation of ground states and another one for the computation of dynamics. A central focus of this paper is also the discussion of implementation aspects that are very important for the practical realization of the methods. In particular, we discuss the use of suitable data structures that keep the memory costs economical. The paper concludes with various numerical experiments in 1d, 2d and 3d that investigate convergence rates and approximation properties of the methods and which demonstrate their performance and computational efficiency, also in comparison to spectral and standard finite element approaches.
Effect of La2O3 and FexO on the viscosity and structure of CaO–MgO–Al2O3–SiO2 melts
Authors: An Zhuoqing , Chen Jiajing , Yuan Fang
Published: May 2024

The effect of La2O3 and FexO on the viscosity and structure of CaO–MgO–Al2O3–SiO2 (CMAS) melt was investigated. The viscosity of CaO–MgO–Al2O3–SiO2 melts with La2O3 and FexO was measured by a rotating cylindrical method from 1375 °C to 1550 °C, and the structures of the melts were analyzed via Raman spectroscopy. The results indicated that the viscosity decreased with increasing temperature and the activation energy decreased from 111.53 to 99.25 kJ/mol with the mole ratio of La2O3/FexO decreased from 2/0 to 0/2. The structural analysis revealed that the weaker chemical bonds or non-chemical bonds between the network structures of the glass were broken with the temperature increases, and both La2O3 and FexO acted as network modifiers to simplify the Si–O–Si tetrahedral structural unit. When the mole ratio of La2O3/FexO decreased from 2:0 to 0:2, the relative fraction of QSi3 and QSi4 decreased and the relative fraction of QSi0, QSi1 and QSi2 increased. Therefore, the degree of polymerization (DOP) of CMAS melt decreased, as well as the viscosity decreased with the addition of FexO and La2O3. FexO has more effective on the decrement in CMAS melt viscosity than that of La2O3 due to the structure modification ability of La3+ being smaller than that of Fe2+. Moreover, the number of non-bridging oxygen atoms per tetrahedrally coordinated atom (NBO/T) was used to characterize the melt structure, the quantitative relationship among the viscosity, temperature and microstructure of the melt was given.
Prediction of desulfurization efficiency and costs during Kanbara reactor hot metal treatment using machine learning
Authors: Zhao Xia , Yang Wu
Published: May 2024

A machine learning model was developed to predict the desulfurization process during the Kanbara reactor hot metal treatment. Compared with other algorithms, the LR algorithm model exhibited the smallest error in current calculations, which was used to predict the final S content with various operation parameters. The final S content in the hot metal obviously rose from 0.001% to higher than 0.003% with the increase of the initial S content from 0.03% to 0.06%, while it decreased from 0.003% to below 0.001% with the increase from desulfurizer addition from 4 kg/ton to 7 kg/ton. The final S content changed little with the increase of C content, Mn content, and rotation speed. The feature selection using RReliefF algorithm was conducted to evaluate the correlation between inputted parameters and outputted final S content. The addition of desulfurizers was beneficial to improve the desulfurization efficiency, while it obviously increased desulfurization costs. The longer desulfurization time lowered the S content, while it resulted in higher desulfurization costs due to the refractory erosion and electric power consumption.
Finanzielle Anreize in der Therapieentscheidung
Authors: Maugg Doris
Published: May 2024

Aktuell laufen in Deutschland 2 Studien, die den Einfluss ökonomischer Anreize auf onkologische Therapieentscheidungen und die Patientengesundheit untersuchen. Erste Ergebnisse des Projekts ELABORATE weisen darauf hin, dass die Entscheidung, ob eine Therapie intravenös oder subkutan verabreicht wird, ökonomisch beeinflusst ist.
Geschlechtsspezifische Unterschiede je nach klinischem Setting
Authors: Kretzschmar Alexander
Published: May 2024

Das Geschlecht beeinflusst die Effektivität von Immuncheckpoint-Inhibitoren (ICI) beim Nierenzellkarzinom (RCC) und Urothelkarzinom (UC) in unterschiedlicher Weise. Zu diesen Ergebnissen kamen Metaanalysen und Netzwerk-Metaanalysen klinischer Studien.
Additives Bevacizumab erhöhte nicht die Lebensqualität
Authors: Krome Susanne
Published: May 2024

Bevacizumab inhibiert den vaskulären endothelialen Wachstumsfaktor (VEGF). Der rekombinante monoklonale Antikörper schließt die Blut-Hirn-Schranke und reduziert damit peritumorale Gehirnödeme. Dies und die kortisonsparenden Effekte legten nahe, dass sich die Lebensqualität von Erkrankten mit Gliomen erhöht, wenn Bevacizumab der Chemotherapie mit Temozolomid hinzugefügt wird. Die Studie TAVAREC bestätigte dies nicht.
Pembrolizumab steigert Rate pathologisch kompletter Remissionen
Authors: Arnheim Katharina
Published: May 2024

Die Immuncheckpoint-Blockade mit Pembrolizumab in der (Neo-) Adjuvanz hat sich beim frühen triple-negativen Brustkrebs bereits bewährt und ist heute Standard. Jetzt liegen positive Daten aus der Studie KEYNOTE-756 zu diesem Vorgehen auch beim frühen Östrogenrezeptor-positiven (ER-positiven), HER2-negativen Brustkrebs vor.
Ribociclib überzeugt auch in der Adjuvanz
Authors: Arnheim Katharina
Published: May 2024

Die finale Analyse der Studie NATALEE mit Ribociclib zum Überleben ohne invasive Erkrankung (iDFS) bestätigt die Effektivität des CDK4/6-Inhibitors beim frühen hormonrezeptorpositiven (HR-positiven) Brustkrebs. Von Ribociclib zusätzlich zur endokrinen Therapie profitieren auch Niedrigrisiko-Patientinnen.
Tucatinib-Regime aktiv bei ZNS-Befall
Authors: Arnheim Katharina
Published: May 2024

Mit der Studie HER2CLIMB-02 liegt jetzt eine 2. Phase-III-Studie vor, die für den Nutzen von Tucatinib-Regimen bei Frauen mit HER2-positivem Brustkrebs und ZNS-Metastasen spricht.
Wichtige Biomarker-Analyse von CheckMate 7FL
Authors: Arnheim Katharina
Published: May 2024

In der Studie CheckMate 7FL bei Hochrisiko-Patientinnen mit einem frühen hormonrezeptorpositiven (HR-positiven) Mammakarzinom hat sich der Checkpoint-Inhibitor (CPI) Nivolumab zusätzlich zur neoadjuvanten Chemotherapie in einer signifikanten Verbesserung der Rate pathologisch kompletter Remissionen (pCR) ausgezahlt. Der Benefit von Nivolumab nahm mit steigender PD-L1-Expression und bei niedriger HR-Expression zu.
SABCS: Erhöhtes Sterberisiko bei kontralateralem Zweittumor
Authors: Arnheim Katharina
Published: May 2024

Brustkrebs-Patientinnen mit BRCA1-Mutation, bei denen ein kontralateraler Tumor auftritt, haben laut Daten einer internationalen Analyse ein doppelt so hohes Sterberisiko wie Patientinnen ohne kontralateralen Zweittumor. Durch eine beidseitige Mastektomie im Rahmen der Erstbehandlung kann dieses Risiko leicht verringert werden.
Nicht kleinzelliges Lungenkarzinom – Vorreiter der personalisierten Onkologie
Authors: Saalfeld Felix Carl , Aust Daniela E , Wermke Martin
Published: May 2024

Bei keiner anderen Krebserkrankung ist die klinische Praxis so nah an den Idealen der personalisierten Onkologie wie in der Behandlung des nicht kleinzelligen Lungenkarzinoms (NSCLC). Wir stellen hier kurz die Grundprinzipien der molekularen Analyse dar. Der Fokus des Artikels liegt auf dem klinischen Nutzen der Therapie. Schließlich zeigen wir die Herausforderungen für das ärztliche Personal und strukturelle Lösungsansätze auf.
Parenterale Ernährung von Risikoneugeborenen
Authors: Haiden Nadja
Published: May 2024

Um nach der Geburt die intrauterine Nähstoffzufuhr ohne Unterbrechung
fortzuführen, ist bei Risikoneugeborenen bzw. Frühgeborenen, bei denen eine
enterale Ernährung nicht oder nur teilweise möglich ist, eine parenterale
Ernährung zur Überbrückung nötig. Dieser Beitrag geht auf die Bereitstellung der
essenziellen Makro- und Mikronährstoffe und weitere wichtige Aspekte der
parenteralen Ernährung von Risikoneugeborenen ein.
Ein Gewichtsreduktionskurs mit dem Schwerpunkt der Stärkung von
„Coping“ Strategien für die low carb Ernährung ist einfach und
erfolgreich
Authors: Lilienfeld-Toal Anna. v. , Tews Dietrich , Lilienfeld-Toal Hermann v.
Published: May 2024

Ein Weg zur Reduzierung des Körpergewichts besteht in der Reduktion der Aufnahme
von Kohlenhydraten mit der Nahrung, sodass geringere postprandiale Anstiege von
Blutglukose und Insulin auftreten. Allerdings führt die Senkung der Blutglukose
zu starken Impulsen in der Regulation der Nahrungsaufnahme. So werden
verschiedene Essimpulse bei Menschen mit Übergewicht ausgelöst, die
Kohlenhydrate in der Nahrung vermeiden. Wir stellten diese Impulse zusammen und
entwickelten ein systematisches Vorgehen, um ihnen zu begegnen. Hiermit bildeten
wir ein Curriculum für einen 1-Jahres-Kurs mit Übergewichtigen, die sich eine
Gewichtsreduktion vornahmen. Die Gruppensitzungen wurden von einer geschulten
Person geleitet. Im Curriculum war zusätzlich ein Austausch über die Erlebnisse
während der Kohlenhydrat-Reduktion enthalten, sowie die Vermittlung von Wissen
über die Pathomechanismen der Gewichtsentwicklung. Weitere Anforderungen an die
Teilnehmer wurden nicht gestellt. Am Ende des einjährigen Kurses reduzierten 18
Teilnehmer aus mehreren Gruppen ihr Gewicht im Mittel um 8,6% vom
Ausgangsgewicht. Parameter des Glukosestoffwechsels besserten sich ebenso wie
psychologische Indikatoren für Essimpulse. Wir nehmen an, dass ein solcher Kurs
in Gruppen, der sich auf die psychologischen Gefahren konzentriert, die mit
einem Vermeiden von Kohlenhydraten in der Nahrung verbunden sind, ein einfach
anwendbarer Weg gegen das Problem des Übergewichtes in jeder spezialisierten
Einrichtung ist.
Update of the competence-based catalog of learning objectives in nuclear medicine for the study of human medicine in Germany
Authors: Heidemanns Stefanie , Trautmann Stephanie , Weidt Daniela , Hellwig Dirk
Published: May 2024

Aim To update the subject-specific, competence-based catalog of learning objectives for medical studies in Germany published by the German Society of Nuclear Medicine (DGN) in 2018, prioritizing relevant learning objectives.

Methods Based on the previous catalog, the writing group compiled nuclear medicine topics and formulated competence-based learning objectives, including medical developments, device innovations and new radiopharmaceutical approvals. These were presented for prioritization to the 180 habilitated DGN members as an expert group in a Delphi process. The first round of voting assessed firstly the topics in terms of necessity or dispensability, and secondly the detailed learning objectives of the topics were assessed for their relevance to academic teaching in nuclear medicine. The results of the first survey were used to draft a catalog of learning objectives with final approval by the expert group in a second survey. The time available for teaching nuclear medicine was also recorded.

Results The writing group developed 240 competence-based learning objectives from 41 topics. After a first Delphi round, 73 detailed competence-based learning objectives from 15 topics were compiled. The mean teaching time was 8.4 h for lectures, 3.7 h for seminars and 3.6 h for practical courses. In a second Delphi round, the agreement of the expert group was at least 95% for the selected topics and at least 90% for the detailed learning objectives.

Summary The catalog of subject-specific learning objectives, updated by expert consensus, provides basic knowledge, skills and competences related to the most relevant diagnostic and therapeutic procedures in nuclear medicine, taking into account both long-established topics and recently introduced innovations.
Patient Demographic Factors Impact KOOS JR Response Rates for Total Knee Arthroplasty Patients
Authors: Tong Yixuan , Rajahraman Vinaya , Gupta Rajan , Schwarzkopf Ran , Rozell Joshua C.
Published: May 2024

The Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) is a validated patient-reported measure for assessing pain and function following total knee arthroplasty (TKA). This study investigates how patient demographic factors (i.e., age, sex, and race) correlate with KOOS JR response rates. This was a retrospective cohort study of adult, English-speaking patients who underwent primary TKA between 2017 and 2023 at an academic institution. KOOS JR completion status—complete or incomplete—was recorded within 90 days postoperatively. Standard statistical analyses were performed to assess KOOS JR completion against demographic factors. Among 2,883 total patients, 70.2% had complete and 29.8% had incomplete KOOS JR questionnaires. Complete status (all p < 0.01) was associated with patients aged 60 to 79 (71.8%), white race (77.6%), Medicare (81.7%), marriage (76.8%), and the highest income quartile (75.7%). Incomplete status (all p < 0.001) was associated with patients aged 18 to 59 (64.4%), Medicaid (82.4%), and lower income quartiles (41.6% first quartile, 36.8% third quartile). Multiple patient demographic factors may affect KOOS JR completion rates; patients who are older, white, and of higher socioeconomic status are more likely to participate. Addressing underrepresented groups is important to improve the utility and generalizability of the KOOS JR.
The effect of local climatic conditions on household consumption: a case study of South Africa
Authors: Mudzingiri Calvin , Mudiriza Gibson , Jana Getrude , Sunge Regret
Published: May 2024

The article explores the causal effect of local climate conditions on household consumption in South Africa. The climatic conditions are represented by monthly average temperature and precipitation. The study utilises the nationally representative 2017 National Income Dynamics Study (NIDS), wave 5 data and 2017 Climate Research Unit (CRU) climate data. The parsimonious quantile regression shows that climatic conditions (precipitation, temperature, wet days, and cloud cover) impact household per capita consumption. The quadratic quantile regression model analysis shows that household per capita consumption is convex in precipitation. Below the turning point, increased precipitation is associated with decreased household per capita consumption. Above the turning point, increased precipitation is related to increased household per capita consumption. Regions that receive very low precipitation or experience extreme temperatures (very cold or very hot) require tailor-made interventions to alleviate consumption. When we control for household characteristics, the impact of climatic conditions on household per capita consumption is weak. Providing inclusive development policies and programmes can mitigate the impact of climatic conditions on household per capita consumption.
Revealing operando surface defect–dependent electrocatalytic performance of Pt at the subparticle level
Authors: Xiao Yi , Guo Zhichao , Cao Jing , Song Ping , Yang Bo , Xu Weilin
Published: May 2024

Understanding the operando defect–tuning performance of catalysts is critical to establish an accurate structure–activity relationship of a catalyst. Here, with the tool of single-molecule super-resolution fluorescence microscopy, by imaging intermediate CO formation/oxidation during the methanol oxidation reaction process on individual defective Pt nanotubes, we reveal that the fresh Pt ends with more defects are more active and anti-CO poisoning than fresh center areas with less defects, while such difference could be reversed after catalysis-induced step-by-step creation of more defects on the Pt surface. Further experimental results reveal an operando volcano relationship between the catalytic performance (activity and anti-CO ability) and the fine-tuned defect density. Systematic DFT calculations indicate that such an operando volcano relationship could be attributed to the defect-dependent transition state free energy and the accelerated surface reconstructing of defects or Pt-atom moving driven by the adsorption of the CO intermediate. These insights deepen our understanding to the operando defect–driven catalysis at single-molecule and subparticle level, which is able to help the design of highly efficient defect-based catalysts.
On the stability of Einsteinian cubic gravity black holes in EFT
Authors: Bueno Pablo , Cano Pablo A , Hennigar Robie A
Published: May 2024

In this note we revisit the analysis performed in De Felice and Tsujikawa (2023Phys. Lett.B843138047) of odd-parity perturbations around static and spherically symmetric black holes in Einsteinian cubic gravity (ECG). We show that the additional propagating modes always have masses much above the cutoff of the theory. Therefore, contrary to what is claimed in that paper, the ECG black holes remain stable within the effective field theory regime. We consider the same analysis for a general cubic theory, showing that the ECG results are not special in this regard. We use the occasion to make some clarifications on the role, uses and limitations of ECG and its generalizations.
Expanding wave packets and the quantum to classical transition
Authors: Briggs John S
Published: May 2024

The standard description of the transition from quantum to classical mechanics presented in most text books is the proof that the quantum expectation values of position and momentum obey equations of Newtonian form. This is the Ehrenfest theorem. It is combined with the requirement that wave packets remain localised to describe a single particle moving according to classical mechanics. Hence, the natural spreading of wave packets is viewed as a quantum effect. In contradiction to this view, here it is argued that the spreading, where different momentum components separate, is the signature of the quantum to classical transition. The asymptotic spatial wave function becomes proportional to the initial momentum space wave function, which mirrors exactly the well-known far-field diffraction pattern in optics. Trajectories, defined as the locus of the normals to the expanding wave front, are used to illustrate the transition from quantum to classical motion. Again this is the analogue of the wave to beam transition in optics. It is suggested that this analysis of the quantum to classical transition should be incorporated routinely into introductory quantum mechanics courses.
An approach to interpreting metastable austenitic material sensors for fatigue analysis
Authors: Heinrich Christian , Gansel René , Schäfer Günter , Barton Sebastian , Lohrengel Armin , Jürgen Maier Hans
Published: May 2024

The transformation of metastable austenite to martensite under mechanical loading can be harnessed to create a material sensor which records a measure of the load history without the need for electrical energy and can be read out at arbitrary intervals via eddy current probing, thus leading to an ultra-low-power sensing solution. This paper presents possibilities of processing this load amplitude-dependent evolution of martensite content loading for component fatigue analysis. The general method is based on using a theoretical material model typically used in finite element analyses which includes hardening plasticity and phase transformation to precompute tables of stress amplitude or cumulative damage corresponding to different sensor readings which can be stored on a low power processing system onboard the component for energy-efficient lookup. At nominal single amplitude loading, the sensor can be used as a load cycle counter for known loads or as an overload detection device upon divergent martensite content rise. Interpretation of block program loading is less practical due to resolution issues. Under random loading, sequence effects get averaged out; interpretation is easiest with narrow load spectra, but information can be gained from very wide spectra as well. Multiple sensors at different locations can aid interpretation. Uncertainty due to necessary assumptions and untreated influences of temperature and loading rate is discussed.
Novel signatures of radiation reaction in electron–laser sidescattering
Authors: Sikorski Philipp , Thomas Alec G R , Bulanov Stepan S , Zepf Matt , Seipt Daniel
Published: May 2024

In this article we investigate novel signatures of radiation reaction via the angular deflection of an electron beam colliding at 90 degrees with an intense laser pulse. Due to the radiation reaction effect, the electrons can be deflected towards the beam axis for plane wave backgrounds, which is not possible in the absence of radiation reaction effects. The magnitude and size of the deflection angle can be controlled by tailoring the laser pulse shapes. The effect is first derived analytically using the Landau–Lifshitz equation, which allows to determine the important scaling behavior with laser intensity and particle energy. We then move on to full scale 3D Monte Carlo simulations to verify the effect is observable with present day laser technology. We investigate the opportunities for an indirect observation of laser depletion in such side scattering scenarios.
Phase diagram and quench dynamics of a periodically driven Haldane model
Authors: Ren 任 Minxuan 民烜 , Yang 杨 Han 焓 , Sun 孙 Mingyuan 明远
Published: May 2024

We investigate a periodically driven Haldane model subjected to a two-stage driving scheme in the form of a step function. By using the Floquet theory, we obtain the topological phase diagram of the system. We also find that anomalous Floquet topological phases exist in the system. Focusing on examining the quench dynamics among topological phases, we analyze the site distribution of the 0-mode and π-mode edge states in long-period evolution after a quench. The results demonstrate that, under certain conditions, the site distribution of the 0-mode can be confined at the edge even in long-period evolution. Additionally, both the 0-mode and π-mode can recover and become confined at the edge in long-period evolution when the post-quench parameters

(

T
,

M
2

M
1

)

in the phase diagram cross away from the phase boundary

M
2

M
1

=

6

3

t
2

M
1

−
1

. Furthermore, we conclude that whether the edge state is confined at the edge in the long-period evolution after a quench depends on the similarity of the edge states before and after the quench. Our findings reveal some new characteristics of quench dynamics in a periodically driven system.
A new framework for evaluating the virgin compression curves of reconstituted clays at different initial water contents
Authors: Lu Xingbang , Qiao Yafei , Ding Wenqi , Li Aiguo
Published: May 2024

The influence of initial water content on the virgin compression of reconstituted clays is a topic of great importance. This study introduces a novel perspective based on the concept of intrinsic compression. It is demonstrated that the virgin compression curves of the reconstituted clays are similar in shape to the intrinsic compression line and can be obtained through vertical shifting and stretching. Building upon this concept, the intrinsic compression line is further extended to the compression curve cluster, enabling a direct evaluation of the influence of initial water content. The validity of the compression curve cluster is verified using independent data from the literature as well as data collected by our research team. In addition, a comparison with other relevant theories further underscores the superiority of the proposed framework.
Visco-elastic model of foamed cement paste under uniaxial compression
Authors: Ye Guanbao , Huo Junhao , Zhang Zhen , Rao Fengrui
Published: May 2024

Foamed cement pastes have been widely used in the backfilling projects, such as road widening and abutment embankment. However, due to its unique porous structures, there have been limit studies focused on developing mechanical model for predicting its engineering behavior. This study conducted a constitutive modeling for describing the mechanical behavior of foamed cement paste. Two types of mechanical element, i.e., elastic element and viscous element, were selected, and their combination was proposed to characterize the basic mechanical properties and behavior of foamed cement paste. By adjusting the combination rules (in series or in parallel) among the basic elements, a strain-based damage element and a visco-elastic-damage combination element model (VED model) were developed based on the MATLAB/Simulink platform. Through a comparison with experimental results, it is demonstrated that the proposed model effectively captures the mechanical behavior of foam concrete under uniaxial compressive loading.
A new method for rapid preparing high-strength saturated clay samples in large-scale model tests
Authors: Masujima T , Xie Y , Zhang Q , Ye G L , Leng J
Published: May 2024

The preparation of high-strength saturated clay samples for large-scale model tests presents a significant challenge in geotechnical engineering. The slurry consolidation method has been conventionally employed to prepare saturated clay, despite its time-consuming and labor-intensive nature. Therefore, this study proposes a rapid preparation technique for clayey soils utilizing the dynamic compaction method, enabling the facile preparation of saturated clay samples by compacting the soils from an unsaturated state. During compaction, the void ratio decreases, thereby increasing the degree of saturation and enhancing the soil strength. Critical to this method are two variables: the moisture water content and the soil density, which are determined through bench-scale compaction tests using the Proctor compaction test apparatus. These tests establish the relationships between moisture content and density, degree of saturation, and soil strength. The moisture content aligning with the target soil strength is selected as the target moisture content for model-scale soil preparation, whereas the moisture content-density relationship sets the target density value. The laboratory tests validate that the soil strength of the saturated model-size clay samples prepared using the proposed method fulfills the requisite criteria, indicating its effectiveness for rapid preparation of high-strength saturated clay samples in large-scale model tests.
Analytical calculation model for elastic modulus and strength of foamed concrete
Authors: Rao Fengrui
Published: May 2024

Foamed concrete has gained increasing attention for its excellent engineering performance. Endeavors have been made to experimentally and numerically elucidate the mechanism of foamed concrete, while few theoretical methods are used to analytically calculate mechanical properties. This paper proposes a theoretical framework to describe the elastic behavior of foamed concrete by combining Eshelby’s equivalent inclusion theory with the Mori–Tanaka method. In the analytical model, foamed concrete is regarded as a two-phase composite comprising a homogeneous cement matrix and randomly oriented ellipsoidal air void. During derivation, the elastic modulus, strength, bulk modulus, shear modulus, and Poisson ratio are measured. A good agreement is established between the proposed method and experimental data.
Exploring the combined effect of particle shape and friction on cell structures in granular packings via LS-DEM modeling
Authors: Jiang Haoran , Kawamoto Reid , Matsushima Takashi
Published: May 2024

To comprehensively understand and predict the macroscopic behavior of a granular system, one must consider not only the properties of individual particles but also the local structures. In this study, we prepare mechanically stable granular packings of super disks using the two-dimensional level set discrete element method (LS-DEM). We identify the cells, the irreducible loops enclosed by contacting particles, in the prepared granular packings and then analyze the statistics of these structures. We find the following. (1) The packing fraction or mean coordination number of studied systems exhibits a non-trivial dependency on particle shapes and inter-particle frictions, making it challenging to establish a direct correlation between them. (2) Using the cell-based description as a bridge, we can measure the packing behavior without considering the influence of particle shape and inter-particle friction. Specifically, the mean coordination number can be explicitly represented as a function of the mean cell order according to Euler’s topological relation. Upon the assumption that all cells are regular polygons, we can also approximately estimate the rattlers-free packing fraction via the mean cell order. (3) We have observed a nearly linear relationship between the mean cell order and rattler fraction. This enables us to determine the packing fraction as well.
Investigation of the fabric effect on the arching effect in granular materials
Authors: Deng Linjie , Dai Beibing
Published: May 2024

A series of trapdoor experiments and DEM simulations were carried out in this study to examine the arching effect in granular materials, with the focus being on the influence of the direction for particle deposition. In the tests, particles (e.g. rice grains, PVC particles and nylon particles) were dropped as if they were raining at different directions to construct granular material layers with various fabric orientations. It is shown that the mobilization of arching effect depends on the direction of particle deposition, with the arching ratio ρ increasing at first and then decreasing. The arching effect is the weakest at a deposition angle of θ = 30° in obliquely deposited granular masses. It is also found that the vertical displacement of particles in the ultimate phase increases initially; it then decreases with the variation in the orientation of particle deposition, and the largest displacement occurs at θ = 30°.
Numerical study on the rupture behavior of funicular liquid bridge between three spheres
Authors: Wang Shaohan , Wang Jipeng
Published: May 2024

Owing to the increase in saturation, unsaturated soil slopes are prone to experiencing landslides and mudflows during the rainy seasons. As liquid volume rises, the funicular regime between multiple particles gradually replaces the pendular regime within unsaturated granular soil. This study establishes a numerical model of a funicular liquid bridge between three spherical particles using the Surface Evolver software. The equilibrium state of the funicular bridge was examined using energy-minimization methods. The effects of liquid volume, contact angle, upper particle-pair gap, and separation distance on the capillary force and rupture distance were investigated. Finally, the relationship between capillary force and rupture distance is further elucidated based on meniscus profiles.
Numerical modeling bearing capacity in wetting unsaturated expansive soils
Authors: Yu Yiting , Peng Huimin , Qian Jiangu
Published: May 2024

To address the load-bearing deterioration of expansive soils uplift pile foundation after moisture absorption, a coupled seepage-soil deformation model for unsaturated expansive soils is implemented into ABAQUS. This modeling work consists primarily of two aspects: (1) The total strain of expansive soils has been decoupled into two parts, i.e., one caused by external loads and calculated by using Mohr-Coulomb plasticity model, and the other induced by wetting swelling and modeled by defining the moisture-swelling relation curve of expansive soils; (2) User-defined field subroutine (USDFLD) is developed by defining suction-dependent soil’s parameters (elastic modulus, cohesion and internal friction angle), and employed to simulate softening behaviors of expansive soils after moisture absorption. he above model is subsequently used to perform 3D finite element modeling and hydraulic-stress coupling analysis on the bearing capacity of pile in expansive soils before and after rainfall. Eventually, the proposed numerical method is validated by simulating a group of full-scale tests.
Slope stability analysis based on rate-dependent soil-water characteristic curve
Authors: Zhiqiang Liu , Gaoxiang Zhang , Yan Liu
Published: May 2024

Rainfall-induced landslides are a common geological hazard. Analyzing this problem necessitates the use of the unsaturated soil theory, with the soil-water characteristic curve (SWCC) being a crucial component. Most existing unsaturated soil seepage models are established based on the static soil-water characteristic curve model. However, the dynamic capillary pressure has been observed in experiments conducted in previous studies. In this study, experiments were performed to explore the dynamic impact of the SWCC. The influence of different infiltration rates was studied, and a rate-dependent SWCC model under dynamic conditions was established. The model was validated through experiments. The behavior of an unsaturated soil slope under different rainfall intensities was analyzed based on the equivalent model. The equation for the slope safety factor was then derived using the Bishop method. The slope safety factors based on both the rate-independent and rate-dependent SWCC models were compared. The results indicated that the safety factor continuously decreased with increasing rainfall intensity. The dynamic effect reduced the safety factor, making the slope more susceptible to instability.
Stability Analysis of Jointed Rock Slopes Based on the Universal Elliptical Disc Model
Authors: Jiang Shui-Hua , Chen Jia-Dong , Huang Jinsong
Published: May 2024

A discrete fracture network (DFN) represents the random distribution of fractures within rock masses in three dimensions and has been widely used in the stability analysis of jointed rock slopes. This study introduces a novel method for constructing three-dimensional DFN models to address the limitations of traditional circular or polygon-based models. This method employs the universal elliptical disc (UED) model, combined with the discrete element method (DEM) in 3DEC, for the probabilistic analysis of jointed rock slope stability. The paper begins with an explanation of the fundamental principles of the UED model, and continues to detail the procedures for creating a three-dimensional DFN using the UED model and for analyzing slope stability using the DEM. An open-pit mine rock slope in the USA serves as a case study to illustrate the application of the proposed method. This approach facilitates the integration of the UED model into 3DEC and offers a more realistic depiction of the three-dimensional DFN, which enhances both the accuracy and efficiency of stability analysis in jointed rock slopes.
Determining Stress Intensity Factors at Varied Inclination Angles through Innovative Discontinuous Digital Image Correlation
Authors: Tian Yuzhe , Zhao Cheng , Xing Jinquan
Published: May 2024

An innovative method is proposed for determining stress intensity factors at crack tips with different inclination angles, based on the Adaptive Digital Image Correlation (AD-DIC) method. This method involves fitting a set of nonlinear equations with unknown parameters using displacement field data. The initial values for crack tip coordinates and inclination angles, computed through the AD-DIC method, are employed in this process to obtain stress intensity factors at the crack tips. The results demonstrate that this approach accurately captures the crack tip positions and calculates stress intensity factors for cracks at various inclination angles. This addresses the challenge of computing stress intensity factors during the crack propagation stage, where cracks may deviate, making conventional calculations impractical.
Elastic-plastic response of tunnel in GZZ-based constitutive model
Authors: Xiao Y M , Qiao Y F , Guo Y F
Published: May 2024

Investigating the stress redistribution characteristics after tunneling is critical for designing and constructing deeply buried tunnels. Three-dimensional stresses are more prominent in deep than in shallow tunnels, resulting in nonlinear strength. The generalized Zhang–Zhu (GZZ) criterion captures the nonlinear strength well. Therefore, this study established a 2D plane-strain numerical model using a GZZ-based constitutive model. The effects of the axial stress and rock properties on the stress redistribution and plastic zone are discussed. The initial axial stresses changed the axial stress distribution after excavation and had little effect on the radial and tangential stress distributions. The size of the plastic zone decreases with decreasing geological strength index and increasing rock mass mi
. However, with increasing dilation coefficient, the stress distributions remained almost unchanged, whereas the radial deformation gradually increased.
Laboratory investigation on injection of supercritical CO2 into basalt: Implication for CO2 sequestration via mineralization
Authors: Zhang Xiufeng , Zhang Fengshou , Song Xuehang , Wei Junjie
Published: May 2024

Hydraulic fracturing can create a fracture network that enables fluid penetration of a basalt formation with otherwise low porosity, offering a site for rapid CO2 mineralization sequestration. Supercritical carbon dioxide (SC-CO2) is a promising fracturing fluid with unique properties, making it well-suited for unconventional oil and gas reservoir stimulation. In this study, experiments of fracturing with water and SC-CO2 were conducted under different injection schemes and formation temperatures. The frackability of basalts was investigated from the perspective of breakdown pressure and fracture morphology. The findings revealed that SC-CO2 fracturing with a low pressurization rate could become an optimized option for enhancing the stimulated effect. The potential of carbon sequestration was roughly estimated based on the area of induced fractures, suggesting that fostering a developed fracture network would aid in the in-situ mineralization and storage of carbon. The variation of element composition obtained from basalt slices containing fractures induced by SC-CO2 under different reaction conditions verified the role of water participation and time scale in the mineralization effect.
Investigating the influence of various three-point bending specimen configurations on rock fracture parameters testing: an experimental study
Authors: Xie Qin , Liu Xiling , Zhong Yuchen
Published: May 2024

The fracture parameters of rocks, including fracture toughness and fracture energy, represent their resistance to crack propagation under external stress. These parameters play a critical role in engineering design, construction safety, geological mechanics research, and rock material assessment. This study determined the fracture parameters of granite under Mode I loading conditions using notched semicircular bend (NSCB) and single-edge notched beam (SENB) specimens. Although there was little difference between the initial and unstable fracture toughness values of the two specimen configurations, significant differences were observed in the fracture process and other fracture parameters. For example, the NSCB specimen exhibits a higher elastic modulus, and it witnessed rapid failure after reaching the peak load, whereas the SENB specimen displayed a more gradual failure process with a distinct post-peak stage. This may be one of the reasons for the higher fracture energy in the NSCB specimen than in the SENB specimen. Based on finite element analysis and the extraction of the tangential stress at the crack tip region, the application of the maximum tangential stress fracture criterion provided a robust explanation for the coherence observed in the unstable fracture toughness test results between the two specimen configurations.
Topology Optimization based Integrated Design of Structure-Foundation System
Authors: Li Xifan , Zhang Xue , Zhang Yujia
Published: May 2024

This study introduces a novel topology optimization method with the goal of achieving an integrated design for offshore infrastructure. A key feature of this method is its capability to eliminate artificial boundaries between the design of the above-ground support structure and underlying soil foundation, thus facilitating a more efficient and effective design solution. In contrast to traditional stress-based topology optimization methods, the proposed approach combines limit analysis with density-based topology optimization techniques. Formulated as a volume minimization task, it targets the structure’s bearing capacity, ensuring that the external force applied is precisely matches the bearing capacity of the system obtained in the design. Furthermore, it is demonstrated that the proposed method exhibits favorable convergence properties within a prescribed number of iterations, indicating a steady progression towards an optimized solution.
Numerical analysis on the behavior of suction anchor under partial drained conditions
Authors: Mu Linlong , Zhou Tao , Huang Maosong
Published: May 2024

The vertical bearing capacity of the suction anchors is closely related to the loading rate. The loading rate is a critical parameter. In this study, ABAQUS was used to perform a numerical analysis of the behavior of suction anchors under partially drained conditions, considering the passive suction generated by the soil, which is the main feature during the uplift process of suction anchors. The results indicated that the suction anchor gradually moved from the drained condition to the undrained condition with an increase in the normalized rate V. When 0.1<V<47, it is partially drained, and the uplift force and negative pressure inside the anchor are more sensitive to the loading rate at this stage.
Evaluation of reduced-scale railway ballast particle size effects for different test sample sizes using monotonic triaxial tests
Authors: Namwong A , Jitsangiam P , Tanchaisawat T
Published: May 2024

This study rigorously investigated the mechanical characteristics of railway ballast using largescale triaxial (LST) testing, focusing on shear strength, stress–strain relationships, and volumetric alterations by altering particle sizes under controlled conditions. Samples with a size ratio (D/dmax) of 4.7 are typically used in LST testing. However, the ballast used in Thailand typically features a maximum grain size of 70.00 mm, whereas LST testing requires samples with diameter exceeding 300 mm, which poses logistical and material challenges. To mitigate this issue, our test introduced a parallel grading method to decrease sample size while preserving essential ballast properties and morphological features. This test applied two grain-size distributions: normal grain-size distribution (NGD) and parallel grain-size distribution (PGD). The study aimed to ascertain whether the smaller-sized samples can still provide accurate assessments of mechanical behaviors. The outcomes demonstrated that both NGD and PGD approaches yielded similar stress–strain behaviors and cohesion values. A marginal difference in friction angle values of 4° was noted, suggesting the occurrence of minor variances in shear resistance, which did not significantly affect the overall mechanical properties. The findings validate the effectiveness of the parallel grading technique, thus offering practical implications for testing procedures in railway engineering.
Morphological analysis of ballast particles: Characterization and simplified analysis of particle morphology using imaging data
Authors: Kwunjai S , Jitsangiam P , Somsri T
Published: May 2024

This paper introduces a novel algorithm for the rigorous characterization of three-dimensional (3D) particles, particularly for railway ballast. Degraded railway ballast must be replaced with fresh material for efficient functioning. This study examined the shape and form of degraded (used) ballast to guide future maintenance efforts. Laboratory-generated used ballast, obtained via the Los Angeles abrasion test, was compared to fresh ballast. Thirteen fundamental morphological parameters of fresh and used ballasts were investigated by utilizing the shape information obtained through 3D scanning. The algorithm efficiently processed datasets comprising multiple irregular particles and monitored the morphological characteristics of ballasts based on the shape of the particles. The trimesh library was imported for 3D processing, facilitating the mathematical calculation of diverse parameters using the developed algorithm. The algorithm also incorporated mechanisms for simultaneously storing parameters provided in various 3D configuration models. With the support of the trimesh library, a morphology analyzer was used to analyze various 3D model file formats, such as .stl, .obj, and csg. This method demonstrated its efficacy with reduced runtime and computation cost. Thus, the proposed algorithm has emerged as a valuable resource for researchers investigating the influence of ballast particle shape on the mechanical behavior of granular assemblies.
Thermo-mechanical Stability Analysis of Hollow Cellular Concrete Block Air Convection Embankments for Cold Regions
Authors: Wu H , Zhang X , Liu J
Published: May 2024

Crushed-rock air convection embankment (ACE), as a highly open-graded porous medium, has been used to mitigate the thaw settlement of pavement structures in permafrost regions. Previous studies have revealed that cellular concrete has significant potential as a cost-effective material for ACE to solve the problem of crushed rock shortage in interior Alaska and improved the thermal stability of pavement structures in cold climates. The design configurations of the hollow cellular concrete block ACE were further designed to maximize the performance benefits and facilitate future implementation and field construction. However, the mechanical behaviors of the proposed structures and ice-rich subgrade were still unknown. In this study, a thermo-mechanical coupling model was developed to evaluate the thermal effect on the long-term mechanical stability of the selected pavement structures and subgrade soils. The results indicated that the thermal stability of the proposed hollow cellular concrete block ACEs was superior to that of the conventional crushed-rock ACE. The maximum thaw settlement of the proposed hollow cellular concrete block ACE was only 13.4% that of the conventional crushed-rock ACE. Thermal and mechanical analyses showed that the proposed cellular concrete ACEs have a significant advantage over conventional crushed-rock ACE.
Fractional derivative modeling for dynamic response of layered viscoelastic media under moving time-harmonic loads
Authors: Ai Z Y , Gu G L , Wang X K
Published: May 2024

The dynamic response of layered viscoelastic media under moving time-harmonic loads is an important issue in transportation geotechnics. However, the existing research often has limitations in terms of the constant creep rate or time-independent relaxation modulus. To fill this gap, this study introduces a fractional Zener model to simulate the viscoelastic properties of media. First, the governing equations of the elastic medium are converted into ordinary differential equations using an integral transform. Subsequently, by introducing the fractional viscoelastic model and extended precise integration method, a solution to the dynamic response of layered viscoelastic media under moving time-harmonic loads is obtained. After comparing the results with those in existing literature, the reliability and accuracy of the proposed solution were verified. Finally, a parametric analysis was performed to further explore the influence of load velocity and fractional order on the dynamic response of the viscoelastic media.