bluuebunny/crossref_metadata_2025 huggingface dataset:
Digital twin for educational purpose, the case study of the U-building at the KTH in Stockholm
Authors: Fonsati Arianna , Gudmundsson Kjartan , Jia Fanglai
Published: May 2024

Nowadays, the Digital Twin (DT) concept is one of the most talked-about topics in the building sector. Previous research has addressed both the definition of DT concept and the development of applications for specific purposes, such as facility and asset management, built environment performance monitoring etc. However, the specificity of such applications reduces both its replicability and understanding. This results in the spread of confusion when approaching such concepts. For this reason, this study explores how DTs can be effectively used for educational purposes. The methods used include the integration of several systems and tools, highlighting different approaches for data integration and capture. The proposed methodology was tested on a real case study, the U-building on the KTH Campus in Stockholm, which is equipped with a Building Management System (BMS). The building is used as a pilot in master courses to allow students to produce a first attempt of using a DT, by connecting real-time monitored data and digital objects. The results show how efficient data communication helps towards the organization and assimilation of complex concepts. Furthermore, the testing of several approaches proves the replicability and flexibility of the method within different environments and for several uses.
Benefits and risks of application of non-metallic composites as an alternative to steel reinforcement in concrete elements
Authors: Dutkiewicz Maciej , Majkowski Paweł
Published: May 2024

The paper presents an overview of possible alternative reinforcement solutions to the most popular steel reinforcement currently used for concrete elements. Particular emphasis was placed on the use of composite reinforcement, taking into account the types of components concerned, possible applications and presenting an analysis of the risks and opportunities facing the construction industry related to the use of this type of reinforcement. In addition, an analysis of the material parameters taking into account the division of composite reinforcement due to the different types of fibers used in their production is presented. The paper also presents a comparative analysis of the parameters of steel and composite reinforcement, among others: tensile strength, susceptibility to corrosion, compressive and bending strength, fire resistance. It also analysed the needs of the construction market in the search for alternative concrete reinforcement in reinforced concrete structures, particularly in the context of recent events such as the Covid-19 pandemic and armed conflicts, which disrupt the supply chain and force the search for alternative materials that can replace reinforced steel. The availability of standards and instructions for the design of concrete elements and the related responsibilities of structural designers were analysed, identifying the research directions necessary to popularize and ensure the safety of the design of concrete elements with the use of alternative material solutions – in particular composite reinforcement in concrete slabs.
Effect of soil-foundation interaction on the modulus of subgrade reaction
Authors: Koltuk Serdar
Published: May 2024

For design of raft foundations, the soil is commonly modelled by using elastic springs, which is based on the Winkler’s theory. In the static analyses, these springs are considered as a constant value k called the modulus of subgrade reaction. However, no foundation is infinitely flexible due to the interaction between the soil and foundation, which is investigated in the present work. For this purpose, the effect of foundation dimensions and foundation material on the subgrade reaction modulus is examined for square-shaped foundations with uniformly distributed load, and the results obtained from these analyses are compared with those in infinitely flexible foundations. It is shown that the effect of Young’s modulus of foundation material on the k-value can be ignored while the foundation dimensions have a great effect on the k-value. The ratio of the subgrade reaction modulus obtained from the analyses taking into account the soil-foundation interaction to the subgrade reaction modulus in infinitely flexible cases varies between 0.36 and 0.45 in the middle area of foundations as well as 0.45 and 0.76 on the edges of foundations with a width between 5 m and 20 m as well as a thickness between 0.25 m and 1.0 m.
Impact on storm water runoff
Authors: Blezniuc Roxana Iuliana , Codruta-Badaluta Minda , Florescu Constantin , Eles Gabriel
Published: May 2024

Hydrological changes, which take place in a hydrographic basin, are due to the rapid growth of urbanization of areas both nationally and globally. Modification of waterproof surfaces, such as streets, sidewalks, parking lots, etc. causes negative changes in the hydrological cycle, as well as groundwater resources, deterioration of water quality, but also ecosystems. In recent years, climate change and poor rainwater management in urban areas have led to a major risk of flooding. This paper analyzes changes in the types of land use coverage and their impact on rainwater discharge, using ArcGIS software.
Definition of indicators for the assessment of the structural condition and riding comfort of cycle paths
Authors: Merkens Torsten , Stöckert Ulrike , Hebel Christoph
Published: May 2024

In recent years, the importance of the bicycle for everyday mobility has increased significantly in Germany. In order to increase the attractiveness of cycle traffic, the provision of safe cycle paths in a good structural condition is necessary in addition to the expansion and new construction of cycling infrastructure. Against this background, the Federal Ministry of Digital and Transport has been funding the research project “Recording and Assessment of the Structural Condition of Urban Cycle Paths” since September 2021. In cooperation with Schniering GmbH and the engineering office Feiler und Hänsel GbR, the University of Applied Sciences Aachen is working on the development of a suitable measurement and assessment procedure. The methods used so far in Germany to record and assess the condition of cycle paths are very much based on the established methods for road condition monitoring and assessment. However, the damage characteristics on cycle paths as well as their effects on road safety aspects, riding comfort and structural value preservation can only be compared with roads to a somewhat limited extent. For this reason, extensive structural assessments of cycle paths were carried out in the research project and a damage catalogue was developed for the recording and assessment of the condition of urban cycle paths. The relevant types of damage are assigned to the following characteristics groups: unevenness, rolling resistance, substance characteristics and vegetation. Based on the results, requirements for the measurement technology and its accuracy could be defined. The conceptual design of a measuring vehicle by the project partner Schniering GmbH will be completed this year and its use tested on various urban cycle paths.
Analysis of the dynamic behaviour of lightweight floor slabs
Authors: Jendzelovsky Norbert , Beutelhauser Daniel
Published: May 2024

Floor slabs are one of the integral load-bearing elements in buildings. When it comes to their serviceability limit state (SLS), one of the key aspects is their dynamic behaviour. In case of residential or administrative buildings, the knowledge of dynamic behaviour of slabs is important in terms of hygiene (psyche) of the user. When speaking of buildings such as medical facilities or laboratories that are using delicate machinery, the knowledge of the dynamic behaviour is important in order to prevent vibration induced damage to given machinery. Therefore, the aim of this paper is to provide a brief overview of standards applicable for assessment of dynamic behaviour, present various methods for calculation of first natural frequency, as well as to present outlines for in-situ measurements, all with special regard to voided slabs.
Bayesian optimization algorithm based support vector regression analysis for estimation of resilient modulus of crushed rock materials for pavement design
Authors: Sandjak Khaled , Ouanani Mouloud
Published: May 2024

The precise determination of the resilient modulus (MR) of the base and sub-base materials is a major preoccupation and a key criterion in the flexible pavement design process. The experimental determination of MR implies a challenging process which requires usually very difficult test procedures and extreme precautions and manpower. This is why soft computing techniques are increasingly popular and of growing importance. Many prediction techniques based primarily on linear and non-linear regression could not provide flexible use and consistent prediction of MR for practical engineering. This article introduces a hybrid of the Bayesian optimization algorithm (BOA) and support vector regression (SVR) as a new modelling tool for the MR prediction of crushed stone materials used as base and sub-base layers for pavement design. For this purpose, an experimental database was utilized to generate the hybrid BOA-SVR model of indirect estimation of the resilient modulus based on material type, basic engineering characteristics and loading conditions. The database consists of 260 experimental datasets obtained from repeated loading triaxial tests performed by the laboratory of the Central Transportation Agency located in Algiers, Algeria. To develop the model, all hyperparameters were optimised using the BOA technique. It was found that the average, median, standard deviation, minimum, maximum and interquartile range of the expected values of the developed hybrid model are very close to the experimental results. Results revealed that the hybrid BOA-SVR model predict the MR of the crushed stone materials with a coefficient of determination of 99.91% and root mean squared error of 3.55. Comparisons with traditional and other Artificial intelligence models showed that BOASVR hybrid model predictions are more accurate and robust than those of other models.
Healing architecture - A different approach of hospital design
Authors: Zubcov Danina
Published: May 2024

Every day, in hospitals around the world, thousands of people spend hours, days, months for investigations, diagnosis or treatment, in search of healing. For patients and their families, the experience of the time spent in the hospital is often a crucial episode of their lives, whether their child was born there, whether it was the place where the life of a family member or loved one has been saved or a bout of illness was cured or treated there. The hospital often represents a milestone in people’s lives, a landmark underlying society’ life. The increase in the number of patients with chronic diseases, of the percentage of aging population and the number of patients requiring treatments influence the hospital’s contemporary approach, and issues such as the above will become even more significant in the future. Future hospitals will have to meet the citizens’ requirements, expectations, but especially their increasingly higher and more diverse needs. In this context, in order to gain the citizens’ confidence, hospitals need to become a safety landmark for the community, where quality care and effective care spaces should be designed and developed so that they provide a positive contribution to the healing process. There is growing awareness that the patients’ evolution and healing are influenced directly by the environment in which the healing process is carried out, so this concept has become the key to architectural layouts when hospitals and health care establishments are being designed or constructed. The aim of this paper is to define and present those innovative features of hospital design – both spatial and aesthetic - that would positively impact on the patients’ healing process. By creating an environment with positive psychological stimuli, reflected in an efficient structure and friendly interior finishings, the architecture of hospitals would support a contemporary approach to the treatment, recovery and healing of the patients.
Urban mobility sustainable plans: Tools and transport policies
Authors: Venezia Elisabetta , Gattullo Mariateresa
Published: May 2024

This paper provides indications on how to develop a Sustainable Urban Mobility Plan (SUMP) in small and medium-sized cities, bringing the case study of an Italian town located in southern Italy, Brindisi. The guidelines are part of the output of the SuMo (Sustainable Mobility in the Port Cities of the Southern Adriatic) project with the aim of specifically improving the sustainability of transport in Brindisi and, in particular, in the port area. The drafting of this paper is based on the dimensional element of the city which allows adopting a path adhering to the needs of the generators and users of a medium-sized city such as Brindisi in order to make the implementation action effective the adoption of the plan follows. The time frame is short-medium term, however, once the sustainability objectives have been pursued, the repercussions are also long-term. The paper anticipates possible solutions and interventions for the Brindisi port area to provide useful ideas in the subsequent phase of drafting and implementing the SUMP itself. In general terms it will be necessary: to improve accessibility for all, regardless of income and social status; to improve the quality of life and the attractiveness of the urban environment; to improve road safety and public health; to reduce air and noise pollution, greenhouse gases, emissions, and energy consumption by limiting individual motorized mobility; to ensure social equity.
Temporary housing environments in urban areas – challenges and key findings for implementation
Authors: Österreicher Doris , Fischer Tatjana , Huber-Humer Marion
Published: May 2024

Cities are increasingly confronted with the need to provide shortterm and cost-efficient housing as several factors, such as natural disasters, migration due to political or climatic circumstances or other unpredictable events can result in a sudden and at times temporary need for additional housing. Providing affordable, and flexible but at the same time sustainable and re-useable housing concepts that are easy to construct and quickly to implement are thus requirements that cities must face. Currently there is limited research available in this field, as disaster architecture and temporary housing have not yet been widely researched in an interdisciplinary manner. The project “Urban pop-up housing environments and their potential as local innovation systems” has aimed at addressing this research gap by investigating in a highly interdisciplinary approach how and under which circumstances temporary housing solutions could be implemented under challenging framework conditions. The aim of the project was to systematically investigate and evaluate existing temporary housing options, and to develop and assess innovative and sustainable models for pop-up living systems in urban environments regarding resource uptake as well as social aspects, which may serve as incubators for urban innovation. From a technical perspective the models are focused on integrating aspects related to architecture, energy technologies, resources and materials, water as well as landscape design. Starting with a data pool of international examples, a classification and systematization of relevant typologies has been carried out in combination with user profiles for the different housing situations. On this basis, potential urban areas have been identified for selected scenarios and finally six theoretical temporary housing models have been created and subsequently assessed and analyzed in detail. The purpose of this paper is to present the key findings related to the scenarios and models, that have been developed within this basic research project and the methodologies that have been applied to assess them. The challenges of the scenarios and overall project results are summarized to provide an outline for potential implementation and future pilot projects.
Impact of artificial intelligence (AI) on industrial design for architect design purposes
Authors: Vasiliu Roland Edgar
Published: May 2024

The paper analyzes the impact of artificial intelligence (AI) on industrial design. It discusses how AI has revolutionized the creation and production processes by automating many steps such as virtual simulation, shape and material optimization and product personalization. It also explores how AI can improve efficiency and reduce costs, as well as contribute to the creation of innovative products and the exploration of new technologies and materials. The research also presents personal examples of the integration of AI in the development of design concepts in teaching activities. At the same time, it discusses the challenges and risks associated with using AI in industrial design, such as the issue of transparency and control over decisions made by algorithms and the loss of jobs in the human sector. The paper concludes with a plea for a responsible and ethical approach to using AI in industrial design, which should leverage its advantages without negatively affecting people or the environment.
Geovisor implementation for visualization of geodynamic and geomorphological properties of the subsoil: Case study Cuenca, Azuay, Ecuador
Authors: Guamán José , Calle Oscar , Maldonado Juan
Published: May 2024

Globally, the development of cities and the increase in their population accelerate construction processes, significantly contrasting with soil studies of the soils on which buildings are built, whose. research results advance at a slower pace than required, often resulting in the occupation of spaces without these previous studies. Mainly due to the null or limited available information is scattered across different sources, files, and formats, and searching for it is a long and difficult process that generates unproductive spaces. This leads to high vulnerability of structures to different events that modify soil behaviour. To address these limitations, the present study aims to generate a standardized database that compiles existing information and processes it so that it can be easily and quickly accessed. A geovisor (based on geographic information systems GIS) is proposed as an ideal way to geographically display on the web the collected data from the studied region (for this work: Cuenca – Azuay – Republic of Ecuador). The information for this study has a seismic focus, being the variables of interest: primary wave speed Vp, secondary Vs, soil type according to the classification of local regulations (NEC-SE-DS) and international SUCS, and soil period. It also incorporates geological and geotechnical information, and stratigraphic subsurface profiles. This constitutes the first national-level database that combines all this information in a single format, forming a great tool for professionals and the community in general in making decisions when infrastructures are emplaced. This information is presented in a geovisor designed for quick access and easy understanding, avoiding the omission of important processes in civil works.
Properties and durability of compressed and stabilized earth blocks using excavated soil rich in limestone
Authors: Messara Kahina , Djadouf Samia , Chelouah Nasser
Published: May 2024

The primary purpose of this study is to assess excavated soil rich in limestone for its use as a raw material in manufacturing Compressed and Stabilized Earth Blocks (CSEBS). Valorization of cut excavation is a promising solution to reduce the strain on natural resources, which aligns with sustainable development goals. The identification of raw materials was performed to study the main properties of blocks manufactured. Samples are obtained by chemical stabilization with the addition of 8% cement. They are compacted at different pressures (1.5, 2.5, 3.5, 5 and 10 MPa) using a hydraulic press. Certainly the stabilization and the compaction of the block contribute significantly to its strength properties but the use of carbonate-rich fine-grained earth has further strengthened the material. The first part of this paper spotlight the measurement of the optimal water content (ɷopt) for the different levels of applied stresses. The second part, presents an experimental study conducted to investigate the thermal-mechanical performance and durability of CSEBS. The compressing strength recorded a value of 16.32 MPa at a compressing stress of 10 MPa and the thermal conductivity observes an increase with increasing the compaction because this tends to densify the mixture. Moreover, the hydrous properties of the compressed stabilized earth blocks are stated by gradually raising the compacting pressure.
Systematic, noninvasive endometriosis diagnosis in transvaginal sonography by the Swiss Society of Ultrasound in Medicine
Authors: Metzler Julian Matthias , Finger Leana , Burkhardt Tilo , Hodel Markus Eugen , Manegold-Brauer Gwendolin , Imboden Sara , Pape Janna , Imesch Patrick , Witzel Isabell , Bajka Michael
Published: May 2024

We present a new systematic, comprehensive, checklist-based sonographic assessment of endometriosis in the female true pelvis. Emphasis is placed on practical skills teaching. The newly introduced White Sliding Line (WSL) is the core structure. The WSL separates five compartments (anterior, central, posterior, and lateral right and left) containing dedicated endometriosis signs of mobility and morphology to be checked. This approach relies on the 2016 IDEA Consensus and further developments. It directly connects to the 2021 #ENZIAN Classification Standard. In practice, evaluation follows the proposed checklist in all compartments, judging first sliding mobility between organs and structures in a highly dynamic investigation. A rigorous search for deep endometriosis (DE) is then performed. We treat adhesions due to their great clinical importance and possible, reliable diagnosis by TVS as the fifth endometriosis unit, next to endometrioma, DE, adenomyosis, and superficial endometriosis. Including superficial (peritoneal) endometriosis is a future goal.
The Eyelid Trans-orbital Trans-cavernous Approach to the Basilar Apex: A Cadaveric Proof-of-Concept Study
Authors: Zhao Xiaochun , Tan Jeremy , Labib Mohamed A. , Desai Rupen , Graffeo Christopher S. , Bauer Andrew M. , Dunn Ian F.
Published: May 2024

Objective The pretemporal transcavernous approach is an elegant technique that provides exposure to the basilar apex, which is conventionally completed with a frontotemporal incision. This can also be performed via a minimally invasive eyelid transorbital approach, which has unique attributes. This is a proof-of-concept cadaveric study to demonstrate details of the combination of these two approaches.

Design This study is a proof-of-concept study using cadaveric heads.

Setting This study is a proof-of-concept study in a cadaveric laboratory.

Participants A latex-injected cadaveric head.

Main Outcome Measures Detailed dissection was performed and demonstrated in a step-by-step fashion.

Results The eyelid transorbital approach provides the exact exposure required to complete the pretemporal osteotomy including an anterior clinoidectomy and dissection, so that a transcavernous approach can be completed. The basilar apex and its branches can also be accessed via the eyelid transorbital approach, with comparable exposure to the traditional approach; however, the access trajectory is much narrower. It takes advantages of the inferior corridor with a more medial access angle and provides a complementary perspective to the cavernous sinus contents and basilar apex complex.

Conclusion The combination of an eyelid transorbital and pretemporal transcavernous approaches can achieve a deep exposure via a minimally invasive incision, which may add an additional approach to the cavernous sinus and basilar apex regions.
The mixed classroom: a pedagogical experiment with students and policymakers
Authors: Pelzer Peter , Hoffman Jesse , Hajer Maarten A.
Published: May 2024

The societal inability to respond accurately to the ecological crisis also requires a reflection on how universities can improve the impact of their practices. This paper reports on a prize-winning experiment aiming to strengthen the interaction of the university with the world of policymaking: a mixed classroom with students and policymakers. This classroom provides an environment in which policymakers and students co-produce insights, while giving policymakers direct access to academic knowledge and helping students to reflect on the dynamics of real-world contexts. The main goal of this study is to illuminate how learning in and through a mixed classroom experiment take places, for participants, teachers and organisational actors. To do so, we reflect on the continuous dialogue between our efforts as teachers and the experience of participants and others involved. To make sense of our teaching and institutional roles in this experiment, we suggest using the concept of ‘tinkering’. Further, to conceptualise the learning dynamics in a mixed classroom, we deploy the concept of ‘boundary crossing’, which turns out to be helpful in elucidating both individual learning (‘reflection’) and organisational learning (‘transformation’). Our study indicates that the notion of boundary crossing helps to effectively capture the learning situation we created and, as such, helps to redefine more generally how the science-policy interface can be understood and acted upon. For other educators interested in deploying mixed classroom-like approaches, we suggest that a tinkering approach can only work if there is sufficient room for experimentation, including failure and reflection, as well as ample time and funding. We also suggest critically looking at the constraints of the institutional logics and dynamics of higher education (e.g. the structure of semesters) and how their connection to the institutional logics and temporal dynamics of real-world contexts may be improved.
A Kundu–nonlinear Schrödinger equation: Rogue waves, breathers, and mixed interaction solutions
Authors: Zhang Xuejie , Zhao Qiulan
Published: May 2024

A Kundu–nonlinear Schrödinger equation that can be utilized to simulate the pulse propagation in optical fibers is researched in this paper. First, the Lax integrability of the above equation is proved and its modulational instability (i.e., the main mechanism for producing the rogue wave solutions and the breather solutions) is calculated. Subsequently, using the generalized perturbation (n,N−n)-fold Darboux transformation, the rogue waves, breathers, and mixed interaction solutions are acquired, as well as the impact of various parameters on the solutions is examined. In particular, when we assume that the coefficient of the equation is θ=mx+dt, some new wave structures are found based on parameter variations, such as the rotational separation of first-order rogue waves, scale-like structures generated by second-order breathers, etc., which offer novel ideas for producing different signals via optical fibers. Ultimately, the classification numbers of mixed solutions of rogue waves and breathers are provided, which can better observe how the two types of the local waves are combined, in accordance with the distributions of the increasing numbers of algebraic equations.
Thermal measurements of boiling granular films
Authors: Zamankhan Piroz
Published: May 2024

This study focused on two familiar items in our daily lives: grains and boiling water. Accurately measuring boiling dense granular beds requires specialized instruments and novel techniques. An annular vertical riser was used to boil granular films. The riser was filled with glass beads and then immersed in liquid water. The water is heated by inducing eddy currents at the base of the riser, which is composed of carbon steel. Beyond the critical electric current, Ic, the Lyapunov exponent of the time series of the measured temperature distributions within the granular films became positive. This indicates the chaotic behavior of the films. Slightly above Ic, patterned instabilities with affine fractal-like structures were observed in the boiling granular films. Chaotic boiling granular films manifested percolation and transition to turbulence. Computer simulations of the above system under the guidance of generative AI (GenAI) successfully reproduced many critical features of the experimental observations, which can be considered a significant breakthrough in the modeling and simulation of complex systems. With this success in utilizing GenAI, more accurate instruments can be developed, resulting in the world of tomorrow rapidly becoming today’s world.
Realization of single MoTe2 crystal in-plane TFET by laser-induced doping technique
Authors: Xie Tianshun , Ke Mengnan , Ueno Keiji , Watanabe Kenji , Taniguchi Takashi , Aoki Nobuyuki
Published: May 2024

Significant recent progress has been achieved in the fabrication of tunnel field-effect transistors (TFETs) utilizing transition metal dichalcogenides (TMDCs) materials, particularly focusing on out-of-plane heterojunction structures. Due to the inherent limitations of doping technology for TMDCs, there have been limited investigations into the development of in-plane TFETs. In this study, we present the realization of an in-plane TFET based on a single crystal of multilayer MoTe2, utilizing a regioselective doping technique through laser irradiation. By constructing a p+/i/n++ homojunction structure, a band-to-band tunneling dominated performance with a minimum subthreshold swing value of 75 mV/dec and an on/off ratio of 105 was obtained at a low temperature. Furthermore, the “OFF” and “ON” state currents of the TFET operation were smaller than the gated diode operation in this structure, which is consistent with the tunneling mechanism.
A compact-size and high-power energy harvester using stacked flexible-PCB coils for rotational shaft applications
Authors: Hoang Van Ai , Lee Young Chul
Published: May 2024

In this Letter, a compact-size and high-power energy harvester (EH) based on multilayer flexible printed circuit board (F-PCB) sheets is presented for wireless sensor system (WSS) applications on propulsion shafts. A 2 mm thin rotor is designed using two F-PCB sheets that integrate 12 coil bundles with a total number of coil turns of 368. A stator is designed in a fixture that can be installed in the bearing housing. Voltage and power of the fabricated EH were measured and analyzed at a rotational speed of 10–100 rpm. At 80–100 rpm, the average voltage and output increased linearly with increasing speed. In particular, at 100 rpm, the average voltage and power were 5.43 V and 1714 mW, respectively. This performance represents a significant improvement compared to previously published EHs. The proposed EH features the straightforward structure, facilitating easier power design and prediction, and it is adaptable to various rotational shaft applications.
On-the-fly kinetic Monte Carlo simulations with neural network potentials for surface diffusion and reaction
Authors: Yokaichiya Tomoko , Ikeda Tatsushi , Muraoka Koki , Nakayama Akira
Published: May 2024

We develop an adaptive scheme in the kinetic Monte Carlo simulations, where the adsorption and activation energies of all elementary steps, including the effects of other adsorbates, are evaluated “on-the-fly” by employing the neural network potentials. The configurations and energies evaluated during the simulations are stored for reuse when the same configurations are sampled in a later step. The present scheme is applied to hydrogen adsorption and diffusion on the Pd(111) and Pt(111) surfaces and the CO oxidation reaction on the Pt(111) surface. The effects of interactions between adsorbates, i.e., adsorbate–adsorbate lateral interactions, are examined in detail by comparing the simulations without considering lateral interactions. This study demonstrates the importance of lateral interactions in surface diffusion and reactions and the potential of our scheme for applications in a wide variety of heterogeneous catalytic reactions.
Theory of acoustic polarons in the two-dimensional SSH model applied to the layered superatomic semiconductor Re6Se8Cl2
Authors: Shih Petra , Berkelbach Timothy C.
Published: May 2024

Layered superatomic semiconductors, whose building blocks are atomically precise molecular clusters, exhibit interesting electronic and vibrational properties. In recent work [Tulyagankhodjaev et al., Science 382, 438 (2023)], transient reflection microscopy revealed quasi-ballistic exciton dynamics in Re6Se8Cl2, which was attributed to the formation of polarons due to coupling with acoustic phonons. Here, we characterize the electronic, excitonic, and phononic properties with periodic density functional theory. We further parameterize a polaron Hamiltonian with nonlocal (Su–Schrieffer–Heeger) coupling to an acoustic phonon to study the polaron ground state binding energy and dispersion relation with variational wavefunctions. We calculate a polaron binding energy of about 10 meV at room temperature, and the maximum group velocity of our polaron dispersion relation is 1.5 km/s, which is similar to the experimentally observed exciton transport velocity.
Pyroelectric crystals for generation of neutrons: A review
Authors: Mohtashami Soroush , Afarideh Hossein , Moshkbar-Bakhshayesh Khalil
Published: May 2024

Over 2300 years ago, the discovery of tourmaline led to the understanding of pyroelectric properties, which opened new doors to various applications of pyroelectric crystal, such as neutron and x-ray generation, energy harvesting, mass spectrometry, high-voltage sources, and more. In the last two decades, researchers have carried out extensive research and development to select components and materials and innovate the design and construction of the pyroelectric neutron generator (PNG). This manuscript investigates the process and history of the PNG’s development. It explains the physics governing pyroelectric crystals and the method of producing neutrons in a comprehensive and straightforward manner. Although PNGs have a lower yield and shorter lifetime compared to other neutron generators, they are still significant for research purposes due to their lack of need for an external high-voltage power supply, lower cost, smaller size, and safety. The main objective of this manuscript is to bring more attention to the research and development of PNGs. In recent years, new methods have been introduced that reduce the amount of neutron flux required for various applications. This has raised hope for the progress of commercial and industrial use of PNGs in the near future. The manuscript mentions some research cases that represent the future perspective of PNG development. Furthermore, the challenges faced by PNGs can be handled more efficiently with the utilization of generative learning algorithms and improvements in the components/mechanisms used for PNG design.
Study of the relationship between large-amplitude neutral sheet oscillations and oblique firehose instabilities during fast flows in the terrestrial magnetotail
Authors: Wei Jiayun , Wang Guoqiang , Zuo Pingbing
Published: May 2024

Flapping motions of the current sheet are a large-scale dynamic process in the terrestrial magnetotail. Some large-amplitude neutral sheet oscillations during fast flows are regarded as flapping motions. In recent years, simulation results suggested that oblique firehose instabilities might be one of their generation mechanisms during fast flows, but this lacks sufficient observational evidence. Here, we statistically investigate the relationship between large-amplitude neutral sheet oscillations and oblique firehose instabilities during fast flows based on observations of the magnetospheric multiscale mission. We find that they have a broad range of period T from 4 to 2000 s. In addition, their propagation velocities (wavelengths) tend to decrease (increase) with the increase in T. About ∼17.6% of the large-amplitude neutral sheet oscillation events are approximately stationary relative to the flow and are linear or quasi-linear polarization, which meets the characteristics of the magnetic field fluctuations generated by oblique firehose instabilities. The probabilities of the fast flows accompanied by large-amplitude neutral sheet oscillations and the probabilities of Cof < 0 (oblique firehose unstable condition) near the neutral sheet have a similar tendency. In addition, T tends to be smaller when Cof is more negative during fast flows. These results suggest that Cof can not only affect the occurrence of the large-amplitude neutral sheet oscillations in the fast flow, but also affect their periods. Our above findings support that oblique firehose instabilities are a generation mechanism of some large-amplitude neutral sheet oscillations during fast flows.
High-temperature superconductor quantum flux parametron for energy efficient logic
Authors: Cai Han , LeFebvre Jay C. , Li Hao , Cho Ethan Y. , Yoshikawa Nobuyuki , Cybart Shane A.
Published: May 2024

We report the fabrication and measurement of quantum flux parametron logic from high-transition-temperature Josephson junctions operating at 25 K, above the temperature of liquid helium. The circuits are written directly into the plane of a single-layer thin film of YBa2Cu3O7 using a focused helium ion beam. A single-cell quantum flux parametron was constructed and correct logic operation was verified by using an on-chip superconducting quantum interference device for readout. A three-cell shift register was also fabricated and tested using a three-phase clock cycle. We estimate the average bit energy to be about 1×10−20 J at 1 GHz.
Percolation transition and bimodal density distribution in hydrogen fluoride
Authors: Feigl Elija , Jedlovszky Pál , Sega Marcello
Published: May 2024

Hydrogen-bond networks in associating fluids can be extremely robust and characterize the topological properties of the liquid phase, as in the case of water, over its whole domain of stability and beyond. Here, we report on molecular dynamics simulations of hydrogen fluoride (HF), one of the strongest hydrogen-bonding molecules. HF has more limited connectivity than water but can still create long, dynamic chains, setting it apart from most other small molecular liquids. Our simulation results provide robust evidence of a second-order percolation transition of HF’s hydrogen bond network occurring below the critical point. This behavior is remarkable as it underlines the presence of two different cohesive mechanisms in liquid HF, one at low temperatures characterized by a spanning network of long, entangled hydrogen-bonded polymers, as opposed to short oligomers bound by the dispersion interaction above the percolation threshold. This second-order phase transition underlines the presence of marked structural heterogeneity in the fluid, which we found in the form of two liquid populations with distinct local densities.
Analysis of dynamic wave model for unsteady flow and sediment transport in alluvial rivers
Authors: Li Zuisen , Wei Ronghao , Zeng Jian , Ding Yun , Guo Yong
Published: May 2024

The coupling interactions between flood propagation, sediment transport, and river morphology in alluvial rivers are mathematically described by the high-order dynamic wave model. The coupling capability of currently used dynamic wave models is systematically conducted. The results indicate that the propagation of a dynamic flood wave only depends on the Froude number, but is independent of the coupling of sediment transport and river mobility. Furthermore, based on the continuum hypothesis, the dynamic equations describing the motion of the active bed layer are obtained. A renewed dynamic wave model is established. Four families of asymptotic solutions to the eigenvalues of the renewed four-order hyperbolic system are obtained by means of the singular-perturbation technology. The results demonstrate that the interactions between flood propagation, sediment transport, and riverbed mobility are coupled. Propagation of the main dynamic flood wave and the dynamic sediment wave will be slower with the increasing deposition rate, but will be faster when the erosion intensity is enhanced. These mainly occur in the lower flow regime. In the process of deposition, the second dynamic flood wave and the dynamic bed wave will propagate both upward and downstream. Besides, the dynamic bed wave will propagate downstream and the second dynamic flood wave will only propagate upstream, regardless of the flow regime.
Conformational and environmental effects on the electronic and vibrational properties of dyes for solar cell devices
Authors: Buttarazzi Edoardo , Inchingolo Antonio , Pedron Danilo , Alberto Marta Erminia , Collini Elisabetta , Petrone Alessio
Published: May 2024

The main challenge for solar cell devices is harvesting photons beyond the visible by reaching the red-edge (650–780 nm). Dye-sensitized solar cell (DSSC) devices combine the optical absorption and the charge separation processes by the association of a sensitizer as a light-absorbing material (dye molecules, whose absorption can be tuned and designed) with a wide band gap nanostructured semiconductor. Conformational and environmental effects (i.e., solvent, pH) can drastically influence the photophysical properties of molecular dyes. This study proposes a combined experimental and computational approach for the comprehensive investigation of the electronic and vibrational properties of a unique class of organic dye compounds belonging to the family of red-absorbing dyes, known as squaraines. Our focus lies on elucidating the intricate interplay between the molecular structure, vibrational dynamics, and optical properties of squaraines using state-of-the-art density functional theory calculations and spectroscopic techniques. Through systematic vibrational and optical analyses, we show that (i) the main absorption peak in the visible range is influenced by the conformational and protonation equilibria, (ii) the solvent polarity tunes the position of the UV–vis absorption, and (iii) the vibrational spectroscopy techniques (infrared and Raman) can be used as informative tools to distinguish between different conformations and protonation states. This comprehensive understanding offers valuable insights into the design and optimization of squaraine-based DSSCs for enhanced solar energy conversion efficiency.
Exploring structures of small anionic nickel–ethanol clusters with infrared spectroscopy
Authors: Dietrich F. , Becherer M. , Bellaire D. , Gerhards M.
Published: May 2024

Small anionic nickel clusters with ethanol are investigated with a combination of mass-selective infrared photodissociation spectroscopy in a molecular beam and density functional theory simulations at the BLYP/6-311g(d,p) and TPSSh/def2-TZVPP level. In this context, the O–H stretching vibration of the ethanol is analyzed to obtain information about the structural motif, the geometry of the metal core, and the spin state of the clusters. For the [Ni2(EtOH)]− and [Ni3(EtOH)]− clusters, we assign quartet states of motifs with a hydrogen bond from the ethanol to the linear nickel core. The aggregation of a further ethanol molecule, yielding the [Ni3(EtOH)2]− cluster, results in the formation of a cooperative hydrogen bond network between the nickel core and the two ethanol molecules.
Optimal strategy of the asymmetric wave energy converter survival in extreme waves
Authors: Zhou Binzhen , Xiao Yi , Ding Kanglixi , Wang Lei , Yang Yifeng , Jin Peng
Published: May 2024

Enhancing the survival performance of wave energy converters (WECs) in extreme wave conditions is crucial, and reducing wave loads is a key aspect of this. Placing the device underwater has been recognized as a beneficial strategy, yet the determination of the optimal submerged depth and the effects of varying wave conditions remain ambiguous. To address this, the study numerically analyzes the total forces in both horizontal and vertical directions, along with their harmonic components, across different wave configurations. A computational fluid dynamics method is employed to investigate a triangular-baffle bottom-shaped oscillating floater, which is known for its high energy conversion efficiency. The findings indicate that submerging the device to a depth equivalent to half the actual focused amplitude (1/2Ab) is the most effective strategy in the given sea state, offering superior wave force reduction vertically and robust performance horizontally. The analysis of harmonics reveals the significant contribution of high-order components to the total wave forces. Additionally, the study examines the impact of focused wave amplitudes and peak frequencies, showing that although force reductions are lessened in more extreme conditions, the optimal submerged depth of 1/2Ab still yields near 30% reduction in total vertical force and 22% in total horizontal force. This research provides theoretical insight that can guide the enhancement of WECs' survival capabilities in practical engineering applications.
Dense-sparse quantum Monte Carlo algebraic diagrammatic construction and importance ranking
Authors: Kulahlioglu Adem Halil , Dreuw Andreas
Published: May 2024

Quantum Monte Carlo Algebraic Diagrammatic Construction (QMCADC) has been proposed as a reformulation of the second-order ADC scheme for the polarization propagator within the projection quantum Monte Carlo formalism. Dense-sparse partitioning and importance ranking filtering strategies are now exploited to accelerate its convergence and to alleviate the sign problem inherent in such calculations. By splitting the configuration space into dense and sparse subsets, the corresponding projection operator is decomposed into four distinct blocks. Deterministic calculations handle the dense-to-dense and sparse-to-dense blocks, while the remaining blocks, dense-to-sparse and sparse-to-sparse, are stochastically evaluated. The dense set is efficiently stored in a fixed-size array, and the sparse set is represented through conventional floating random Monte Carlo walks. The stochastic projection is further refined through importance ranking criteria, enabling a reduction in the required number of walkers with a controllable bias. Our results demonstrate the integration of dense-sparse partitioning with importance ranking filtering to significantly enhance the efficiency of QMCADC, enabling large-scale molecular excited-state calculations. Furthermore, this novel approach maximizes the utilization of the sparsity of ADC(2), transforming QMCADC into a tailored framework for ADC calculations.
An efficient and universal parallel algorithm for high-dimensional quantum dynamics in poly-atomic reactions
Authors: Zhou Yong , Lu Yunpeng , Zhang Zhaojun , Zhang Dong H.
Published: May 2024

This study presents a parallel algorithm for high-dimensional quantum dynamics simulations in poly atomic reactions, integrating distributed- and shared-memory models. The distributions of the wave function and potential energy matrix across message passing interface processes are based on bundled radial and angular dimensions, with implementations featuring either two- or one-sided communication schemes. Using realistic parameters for the H + NH3 reaction, performance assessment reveals linear scalability, exceeding 90% efficiency with up to 600 processors. In addition, owing to the universal and concise structure, the algorithm demonstrates remarkable extensibility to diverse reaction systems, as demonstrated by successes with six-atom and four-atom reactions. This work establishes a robust foundation for high-dimensional dynamics studies, showcasing the algorithm’s efficiency, scalability, and adaptability. The algorithm’s potential as a valuable tool for unraveling quantum dynamics complexities is underscored, paving the way for future advancements in the field.