bluuebunny/crossref_metadata_2025 huggingface dataset:
Intention inference‐based interacting multiple model estimator in photoelectric tracking
Authors: Sun Minxing , Liu Huabo , Duan Qianwen , Wang Junzhe , Mao Yao , Bao Qiliang
Published: April 2024

Aiming to improve the estimation and prediction accuracy of a target's position, this paper proposes a state estimation method for photoelectric tracking systems, based on the evaluation of the tracked target's motion intention. Traditional photoelectric tracking systems utilize external physical quantities such as the position, velocity, and acceleration of the target as the estimated states. While this method can output good results for pre‐modelled target positions, it struggles to maintain the accuracy when facing manoeuvering targets or complex motion patterns targets. Here, the relevant parameters of the tracked target's motion intention are directly estimated innovatively, like estimating the circling point position rather than the circular flying target's position and velocity. This approach enables recognizing the target's motion intention and leads to precise estimation, which specifically consists of an interacting multiple model approach, multiple unscented Kalman estimators, and a robust estimator. The effectiveness and stability of this estimator are validated through software simulations and experiments on a dual‐reflection mirror platform.
Towards Sustainable Energy Conversion: Green Synthesis of Nanostructured Catalysts
Authors: Vatin Nikolai Ivanovich , Pandey Alok Kumar , Singh Takveer , Samrat Bhavuk , Kumar P. Prashanth
Published: April 2024

This research investigates the creation, analysis, and assessment of nanostructured catalysts designed specifically for sustainable energy conversion purposes. Nanostructured catalysts were produced by a modified sol-gel technique, employing different ratios of precursor materials and reaction conditions. The morphological analysis showed clear disparities among the catalysts that were manufactured. Catalyst 3 had the most favorable attributes, such as a substantial surface area and pore volume. Catalyst 3 exhibited exceptional electrochemical performance, showcasing remarkable activity and selectivity. It achieved high current density and faradaic efficiency while maintaining low overpotential. The stability tests demonstrated the durability of Catalyst 3, as it showed very little decline in electrochemical performance after several cycles. These results emphasize the need of methodical tuning of synthesis parameters to customize nanostructured catalysts for particular energy conversion applications. In the future, it is important to concentrate on improving the methods used to create something and discovering new combinations of substances that can speed up the process of converting energy in a way that is efficient and does not harm the environment. Nanostructured catalysts have the potential to significantly contribute to the advancement of clean energy technology and the reduction of global environmental consequences by tackling these difficulties.
Nanotechnology-enabled Solutions for Water Purification and Environmental Sustainability
Authors: Gudainiyan Jitendra , Kumar Rahul , Singh Dhiraj , Sing Durgeshwar Pratap , Shrivastava Anurag , Srivastava Arun Pratap , Khan Akhilesh Kumar
Published: April 2024

This research investigates the transformative potential of nanotechnology in tending to water refinement challenges and advancing natural supportability. Carbon nanotubes and graphene were synthesized and joined into nanostructured channels, showing a well-defined arrangement with predominant basic keenness affirmed through SEM and XRD investigations. In comprehensive water decontamination tests, these channels showcased momentous efficiencies: overwhelming metals, such as lead (Pb) and cadmium (Cd), were expelled at rates outperforming 98% and 97%, individually; natural poison methylene blue displayed an amazing evacuation productivity surpassing 99.5%; microbial contaminant Escherichia coli was successfully killed, accomplishing a momentous expulsion effectiveness of 99.9%. Comparative investigations with related studies underscored the competitive or prevalent execution of the nanostructured channels. Additionally, a life cycle appraisal (LCA) highlighted the commitment to natural maintainability, uncovering generally moo nursery gas outflows (450 kg CO2e), vitality utilization (550 MJ), and asset consumption (10 kg) related to the filters’ whole life cycle. The inventive integration of nanotechnology into water treatment techniques exhibits the potential for effective, feasible, and intriguing approaches, laying the establishment for the advancement of progressed innovations fundamental for worldwide water resource conservation.
IoT-Enabled Predictive Maintenance for Sustainable Transportation Fleets
Authors: Mittal Vaibhav , Devi P. Srividya , Pandey Alok Kumar , Singh Takveer , Dhingra Lovish , Beliakov Sergei I.
Published: April 2024

This research examines the profound effects of integrating IoT-enabled predictive maintenance in sustainable transportation fleets. By using real-time sensor data, this implementation aims to enhance fleet dependability and operational efficiency. The fleet, including a variety of vehicles such as electric buses, hybrid cars, electric trucks, CNG-powered vans, and hybrid buses, is constantly monitored using IoT sensors that capture important characteristics like engine temperature, battery voltage, and brake wear percentages. The predictive maintenance algorithms adapt maintenance schedules in response to live sensor data, enabling a proactive strategy that tackles prospective problems before they result in major failures. The examination of the maintenance records reveals prompt actions, showcasing the system’s efficacy in reducing operational interruptions and improving the overall dependability of the fleet. Moreover, the examination of percentage change confirms the system’s flexibility, demonstrating its capacity to anticipate fluctuations in engine temperature, battery voltage, and brake wear. The findings highlight the system’s ability to adapt to various operating situations and its contribution to lowering maintenance expenses while enhancing operational effectiveness. The established approach incorporates ethical issues, such as data security and privacy, to ensure responsible adoption of IoT technology. This study has broader ramifications beyond the particular dataset, providing a detailed plan for incorporating IoTenabled predictive maintenance into contemporary transportation infrastructures. The study’s findings offer valuable insights into the potential of proactive maintenance strategies to transform the transportation industry towards sustainability. This contributes to a future where fleets operate with increased efficiency, reduced environmental impact, and improved reliability.
Green Catalysts for Sustainable Biodiesel Production from Waste Cooking Oil
Authors: Mittal Aman , Negi Gaurav Singh , Singh Preetjot , Kaur Savinder , Dayawati  , Kumar A. Vinay
Published: April 2024

Biodiesel manufacturing from waste cooking oil has emerged as a potential alternative in the search of sustainable energy. This process helps mitigate environmental pollution and reduces reliance on fossil fuels. This research examines the catalytic efficiency of environmentally friendly catalysts in this process, with a specific emphasis on catalysts based on enzymes. It assesses their effectiveness in terms of the production of biodiesel, the rate of the chemical reactions, cost efficiency, and their influence on the environment. Experimental evidence demonstrates that enzyme-based catalysts have enhanced catalytic activity, leading to an average biodiesel production of 90%, outperforming traditional catalysts such as solid acids, bases, and heterogeneous metal catalysts. Moreover, enzyme catalysts exhibit enhanced reaction rates due to their unique enzymatic activity and gentle reaction conditions. The cost study shows that the manufacturing costs for enzyme catalysts are competitive, with an average total cost of $800, which is equivalent to traditional catalysts. Environmental impact evaluation emphasizes the sustainability of enzyme catalysts by demonstrating their lower energy consumption, waste production, and greenhouse gas emissions compared to traditional alternatives. The results highlight the capacity of green catalysts, namely enzyme-based catalysts, to enhance sustainable biodiesel production methods, hence promoting a more eco-friendly and robust energy framework.
Renewable Energy Integration for Urban Sustainability A Nanomaterial Perspective
Authors: Bhong Mahesh , Singh Rahul , Singh Pradeep Kumar , Nirsanametla Yadaiah , Verma Rajesh Prasad , Saraswat Manish , Srivastava Amit
Published: April 2024

This research explores the transformative part of nanomaterials in progressing urban maintainability through the integration of renewable vitality frameworks. Synthesized quantum dabs, carbon nanotubes, and graphene were characterized and connected over assorted applications, counting solar vitality saddling, wind vitality improvement, vitality capacity, and urban foundation improvement. In solar cells, the integration of quantum specks resulted in an eminent increment in control transformation proficiency (PCE), with an 85% change in short-circuit current thickness (J sc) and a 20% increment in open-circuit voltage (Voc). Wind turbine edges upgraded with carbon nanotubes displayed a momentous 21% rise in control yield and a 40% advancement in soundness, emphasizing the potential of nanomaterials in optimizing wind vitality frameworks. Graphene-based supercapacitors illustrated a multiplied particular capacitance and a 10% increment in cyclic solidness, underscoring the adequacy of nanomaterials in vitality capacity applications. The consolidation of nanocomposite building materials showcased a 44% diminishment in warm conductivity, contributing to made strides cover for maintainable urban foundations. Nanosensors, coordinated into smart frameworks, showed a prevalent 80% increment in affectability and a 50% lessening in reaction time compared to customary sensors.
Research on TOD Development and Location Selection among All Urbanized Areas – A case study in China
Authors: Song Jia , Zhang Junyao , Liu Ding , Lin Xue , Zhu Xina
Published: April 2024

Currently, China is in the period of rapid urbanization and gradual improvement of the rail transportation network. With the increasing population in towns, the construction of many cities has become blind and disorderly to meet people’s housing needs, resulting in traffic congestion, uneven distribution of resources, and other “big city diseases” more serious. From the urban construction experience of developed countries, the mode that urban rail transportation and urban development complement each other and develop together, that is, the regional-wide TOD construction, is an effective way to promote sustainable urban development. This paper focuses on how to select the stations of the rail transit for priority development of TOD projects (TOD development advance sites) within the whole area of the town. When selecting stations, the investment potential and regional driving ability of each station are taken into consideration to make a comprehensive evaluation of each rail transit station, so that the TOD development advance sites can drive the gradual development of its surrounding areas and finally form an urban renewal pattern of interoperability and integrated development of the whole area. With this method, we can effectively solve the current situation of blind and disorderly construction of TOD and various problems in urban development in China, and help to build efficient, green, and livable cities in various places.
Conservation Study of Hakka Architecture Nanyuan Shidi Wailong House
Authors: Chiu Chen-Yuan , Cai Fupeng , Dong Zuorong , Shen Fei , Lan Keran , Zeng Xinyue , Deng Shiyun
Published: April 2024

In Chinese traditional culture, the Hakka spirit embedded in traditional Hakka buildings occupies an extremely important position, and if the protection method is not appropriate, it will damage the typical buildings inherited by the Hakka for centuries, which is not conducive to the cultural inheritance of the Hakka. Traditional restoration methods are difficult to accurately and completely restore the original buildings due to reasons such as low efficiency, aging equipment and thus inability to achieve the expected restoration results. Based on the point cloud data obtained from CAD processing by 3D scanning technology, a comprehensive 3D building model information is established to form a building structure database, which is helpful for the formation of the Hakka traditional building database.
Dynamic Adjustment of Long-Term Maintenance Plan Based on Gray Wolf Optimizer
Authors: Qi Jihui , Wang Yanchao , Bai Zhengfeng , Fu Xuyun
Published: April 2024

Aeroengine is an expensive large-scale precision and complex equipment, in the operation process needs to be repaired and maintained many times. The current management of civil aeroengine is generally aeroengine fleet as a unit, the development of maintenance plans, but once the maintenance plan is determined, if encountered unplanned disturbances, such as aeroengine repair ahead of schedule and other emergencies, the maintenance plan cannot make self-adjustment, it is difficult to be applied to the engineering practice. In view of the above problems, this paper proposes and establishes a dynamic adjustment model for long-term fleet maintenance plan by considering the actual needs of engineering and combining with the research on dynamic scheduling. In this model, the optimization goal is to minimize the cost generated by engine shortage and engine waste, minimize the balanced index of repair delivery, and minimize the difference between the plans before and after dynamic adjustment. Using the gray wolf optimization algorithm (GWO) for solving, the dynamic adjustment model is compared with the nondynamic adjustment model in a comparative test, and the accuracy and practicality of the dynamic adjustment model are verified.
Energy efficiency and energy-saving evaluation methods for public building energy systems under the dual carbon background
Authors: Wang Pin , Bai Yunlong , Zhang Shikang , Li Zhi , Han Hao
Published: April 2024

The energy consumption characteristics and energy system structure of each type of building are different, so the evaluation methods and indicators need to be customized for different types of buildings, which increases the complexity of the evaluation. Therefore, a method for evaluating the energy efficiency and energy conservation of public building energy systems under the dual carbon background is proposed. Analyze the coupling coefficient data of energy quality, energy and flow, obtain the base of energy efficiency optimization coefficients, and use twin technology to establish a comprehensive energy efficiency model. Introduce matter element analysis and use matter element extension models to evaluate the energy efficiency and energy-saving effects of public building energy systems. The experimental test results show that the research method can accurately evaluate the energy consumption of public buildings and has an effective evaluation effect on different types of buildings.
A Parametric Analysis of the Planes of the Existing Neoclassical Architecture of the Oldest Churches in Macau
Authors: Tang Wei , Tang Jian , Huang Gecun , Ye Tingting
Published: April 2024

The three oldest churches in Macao are all listed in the UNESCO World Heritage List. The existing buildings of St. Lawrence’s Church and St. Anthony’s Church are both the neoclassical style. There is few parametric analysis of these two churches. This study takes the planes of St. Lawrence’s Church and St. Anthony’s Church as the research objects, and parameterizes the geometric composition characteristics of the designs.
Research on Key Technologies for Green Transformation of Existing Residential Buildings in Dense Urban Areas
Authors: Liang Xiaodan , Wang Dan
Published: April 2024

To achieve green and environmentally friendly urban construction, it is proposed to study a key technology for the green transformation of existing residential buildings in densely populated urban areas. Firstly, using a time series autoregressive model, achieve energy consumption prediction for HVAC heating. Secondly, based on multi-objective particle swarm optimization algorithm, energy-saving control of HVAC systems was achieved. Finally, the effectiveness of the proposed key technology was verified through experiments. The results of this article indicate that the green transformation of existing residential buildings in densely populated urban areas is necessary and feasible, and the application of key technologies can effectively reduce energy consumption and improve the quality of the living environment.
The Impact of the Two Pandemics on Sustainable Urban Housing Development
Authors: Zhou Shuiying , Peng Miao
Published: April 2024

People had to stay in their homes for long time during the pandemic like SARS or COVID-19. Under this experience, people put forward many opinions and suggestions on the current situation of urban residential architecture design and community planning. The existing deficiencies can be learned form people’s perceptions and the findings is helpful to the sustainable development of cities. Based on the literature survey, the main issues of public dissatisfaction after SARS are summarized and analyzed. An online survey-based households was conducted to explore the updated housing, environmental, and psychological focal points caused by the prolonged COVID-19 pandemic. The main concerns of urban residents on house and community design and planning after the two pandemics are described and reviewed. It is found that there are additional focus on residential buildings and the community environment after the two pandemics. People are still very concerned about elements such as sunlight, natural ventilation, and sewage treatment to prevent the virus transmission. Some deficiency in housing and communities still leave urban residents dissatisfied, and existing urban housing and community designs may still not be ready for the next pandemic. The pandemic has not only renewed awareness of some important basic elements of urban living that cannot be ignored, but has also brought about changes in people’s lives.
Research on the Construction of Public Cultural Space of Changxindian Historical and Cultural Town under the Background of Urban Renewal
Authors: Kang Qi , Huang Mingjin
Published: April 2024

As a famous town located in the west of Beijing with a long history of thousands of years, Changxindian is currently facing a host of difficulties such as backward industrial economic development, a chaotic living environment, and a sharp decline in urban vitality. In addition, public cultural space, serving as an important place for residents to conduct leisure activities, is indispensable in improving residents’ quality of life, stimulating urban vitality, and other aspects. In this regard, by combining the protection and renewal of the old town with the redevelopment of the public cultural space, this research deeply investigates the problems exposed by the constructed public cultural space within the old town, the characteristics of spatial evolution as well as relevant influencing factors through field research and statistical analysis. Meanwhile, combined with residents’ vision and master plan, this research puts forward corresponding promotion strategies and recommendations for diverse types of public cultural spaces, with a view to providing a valuable decision-making basis for further exploring how to effectively utilize the existing urban cultural resources in old towns and to mend and promote urban public cultural spaces with regional characteristics..
Multiple Scenario Simulations of Land Use in Guangzhou City Based on the PLUS Model: Strategies for Sustainable Urban Planning
Authors: Ma Xiuying , Zeng Huixian , Guo Juan , Wu Wenkun
Published: April 2024

Against the backdrop of rapid urbanization, this study employs the Patch-based Land Use Simulation (PLUS) model to investigate land use dynamics in Guangzhou City over the last twenty years. The analysis reveals significant conversion of agricultural and forest lands into urban construction sites, driven by a complex interplay of natural and socio-economic factors. The PLUS model’s scenario simulations highlight the challenges of urban expansion on ecological spaces and sustainability. Findings suggest that Guangzhou City should adopt comprehensive land planning strategies that balance urban growth with ecological conservation. This involves implementing strict land use planning, optimizing urban layouts, and promoting ecologically friendly urban development methods. These recommendations aim to facilitate sustainable urban planning in Guangzhou, ensuring a harmonious coexistence between urban development and environmental preservation.
Discussion on low-carbon energy supply and scour protection technology for cross-sea bridges combined with tidal current energy
Authors: Xie Yu , Yu Tao , Zhu Wei
Published: April 2024

In the context of achieving carbon peak and carbon neutrality, the construction and maintenance of transportation infrastructure should also comply with the requirements of green and low-carbon development. There are many long-span cross-sea bridges in Zhejiang Province, which consume large amounts of electricity for lighting, dehumidification, and anticorrosion, etc., and the energy required usually relies on external energy transfer, which is costly and intermediate losses are high. Tidal current energy, which is the kinetic energy generated during ebb and flood tides, is abundant along the coast of Zhejiang Province, mainly concentrated in Hangzhou Bay and Zhoushan Islands, which is also a dense area of sea-spanning bridges, and the foundation of sea-spanning bridges often suffers from severe scouring to the strong tidal current action. This paper discusses two forms of joint development of tidal current power generators and cross-sea bridges, analyses the advantages and disadvantages as well as the feasibility of each scheme, and gives suggestions for subsequent development.
Analysis of drainage capacity of tunnel during construction period
Authors: Yang Shaojia , Liu Xiaoyu , Li Gaohui , Wang Jinfeng , Zhu Hongbo
Published: April 2024

In the process of excavation of underground tunnels, water gushing is often accompanied. In order to avoid affecting the construction schedule and safety, it is necessary to accurately evaluate the drainage capacity. In this paper, the drainage capacity of the tunnel is reviewed and calculated, and the effects of longitudinal slope, steel arch and roughness are considered. The drainage capacity under different conditions is analyzed by the formula of uniform flow in open channel.
Understanding bikeshare mode as feeder to bus:A case study of Chicago’s Divvy system
Authors: Xiang Yunhu , Xiang Zhili
Published: April 2024

The bike-share system gives a decent solution to the first- and last-mile problem. And it connects trip origins/destinations and transit stations. However, current research in this area focuses more on metrobikeshare pattern, and there are still substantial gaps in research in the area of bus-bikeshare pattern. Focusing on Chicago, this study uses Divvy’s location information data to explore the spatial and temporal characteristics of bus-bikeshare transfer trips. Besides, we examine the built environment factors affecting bus-bikeshare transfers. This study uses buffers and time limits to isolate bus-bikeshare transfer trips. Two recognition rules proposed are a maximum transfer time of 20 min and a maximum buffer distance of 100 m. The findings are listed as follows: (1) the average distance and duration of bus-bikeshare trips is 1740.95m and 548.11s; (2) the bus-bikeshare trips show characteristics in different areas, seasons and periods; (3) there is a positive and significant spatial autocorrelation for the bus-bikeshare trips; (4) The bus-bikeshare pattern is influenced by built environment factors in a manner distinct from the bikeshare-only pattern, exhibiting its own unique characteristics.
Research on classification of highway service areas based on multifactor clustering
Authors: Zhen Cao , Hui Sunyu , Juan Geng , Zhun Tian
Published: April 2024

This article proposes a classification method for highway service areas. POI (Point of Interest) data and surveys provide information on the area of highway service areas, distance from city centers, regional economic conditions, and population data. The clustering tendencies are analyzed using the Hopkins statistic, the number of clusters is determined using the elbow method, and the advantages and disadvantages of K-Means, FCM (fuzzy c-means), and HC (Hierarchical Clustering) are assessed using the CH (Calinski Harabasz), SC (Silhouette Coefficient), and DB (Davies-Bouldin) index. Using data from 95 highway service areas in Shaanxi Province as an example, The research findings indicate that the K-Means outperforms the FCM and HC according to all three evaluation indicators. Therefore, the article employs the K-Means to classify the 95 highway service areas in Shaanxi Province into three categories. The classification results obtained from this study provide a basis for the comprehensive development of highway service areas and the surrounding land.
Optimization of intermodal routes for reefer containers under double uncertainty
Authors: Peng Xue , Heng Zhang , Xi Chen
Published: April 2024

Aiming at the influence of demand uncertainty and stochastic carbon trading price on the choice of intermodal transportation route for reefer containers, a hybrid robust stochastic optimization model with minimum economic cost is established, and a Monte Carlo sampling-based catastrophic adaptive genetic algorithm is designed to test the reasonableness and validity of the model. The results show that: influenced by the regret value constraint, the robust optimization of demand uncertainty will increase the total cost of reefer container multimodal transportation, while the increase of carbon trading price stochasticity doesn’t necessarily mean the increase of cost, and the reasonable setting of carbon trading price stochasticity and the trade-off between the maximum regret value and the economic cost, so that the cold-chain logistics and transportation enterprises can easily deal with the fluctuation of the demand of the freight transportation market, and also respond to the low-carbon requirements.
Evaluation index system of competitiveness of county commerce and trade circulation market
Authors: Zheng Fengli , Dai Jiamin , Liu Huaqiong
Published: April 2024

In order to further study the development level of county-level commercial circulation industry, this article takes Dezhou City as the research object. It selects core indicators from three aspects: scale, business format, and socio-economic development, constructs an evaluation system for county-level commercial circulation, uses principal component analysis and cluster analysis to evaluate commercial competitiveness, and sorts and categorizes them. The results show: there are significant differences in the differentiation of commercial and trade circulation capabilities within Yucheng City. There is significant room for improvement in the overall level of collaboration. In the future, we should continue to optimize the level of county level commercial and trade competitiveness by enhancing internal collaboration and accelerating rural infrastructure construction.
Study on cruise speed optimization and refueling strategy considering emission control areas
Authors: Xi Chen , Heng Zhang , Peng Xue
Published: April 2024

In order to alleviate the cost pressure caused by navigation restrictions and rising fuel prices faced by cruise companies, on the basis of considering the constraints of emission control areas and the arrival time constraints of each port, according to the relationship between the speed and fuel consumption of ships during navigation, a mixed integer nonlinear programming model with the minimum sum of the sum of ship fuel replenishment cost, arrival delay penalty cost and carbon tax cost is established to optimize the speed and refueling strategy of cruise ships. The results show that with the change of fuel price and time constraints, the fuel replenishment strategy will also change.
Research on Evaluation Indicators for Maritime Firefighting Capabilities
Authors: Chen Yihao
Published: April 2024

As a prominent maritime and shipping power, our nation is actively engaged in the development of a formidable maritime and transportation infrastructure. The enactment of the “Maritime Silk Road” strategy, coupled with the growing expansion of maritime transport, necessitates the urgent formation of a commensurate maritime firefighting force to elevate readiness against significant emergent incidents at sea. The construction of evaluative indicators for maritime firefighting capabilities is crucial in advancing these capabilities further. This advancement is pivotal for enhancing service to national strategies, preserving national sovereignty and maritime security, and for engaging deeply in the governance of global maritime affairs.
Merging tissue engineering models with systems biology analysis for more collaborative understanding
Authors: Thompson Avery
Published: April 2024

The two fields have much to gain by working together and taking advantage of each other’s recent developments.
Dispersion of two-photon absorption and nonlinear refraction in
β
-Ga2O3 from 350 to 515 nm
Authors: Tian Xiao , Lu Hai-shuang , Qian Tianxiang , Zhou Wenfa , Yang Junyi , Yang Xifeng , Ju Sheng , Li Zhong-guo , Song Yinglin
Published: April 2024

We report the wavelength dependencies of the two-photon absorption coefficients β as well as the nonlinear refractive index n2 of undoped β-Ga2O3 single crystal in the spectral range 350–515 nm (0.51 < Ephoto/Eg < 0.75). Femtosecond Z-scan measurements show that n2 decreases monotonically toward the shortwave side, while the maximum value of n2 is 5.0 × 10−19 m2/W near half of the bandgap, Eg. Interestingly, a second upward trend in β was observed when the incident photon energy is larger than 0.6Eg, indicating the impact of additional inter-band transitions with higher energy. A higher-energy band-to-band transition around 6.0 eV was determined by both femtosecond nondegenerate two-photon absorption spectroscopy and ab initio calculations. Our results could provide guidance for designing nonlinear β-Ga2O3 photonic devices in the UV-visible spectral range.
Evolution of the pentacene exciton band width in pentacene–tetracene blends
Authors: Hubenko Kateryna , Kusber Anncharlott , Naumann Marco , Büchner Bernd , Knupfer Martin
Published: April 2024

Pentacene is one of the most investigated organic semiconductors. It is well known that the motion of excitons in pentacene and other organic semiconductors is determined by inter-molecular exciton coupling based on charge-transfer processes. In the present study, we demonstrate the impact of the admixture of tetracene, which has a larger band gap and interrupts the pentacene–pentacene interaction, on the exciton behavior in pentacene. Using a combination of optical absorption and electron energy-loss spectroscopy, we show that both the Davydov splitting and the exciton band width in pentacene strongly decrease with increasing tetracene concentration, while the decrease of the exciton band width is substantially larger.
Terahertz nanoscopy: Advances, challenges, and the road ahead
Authors: Guo Xiao , Bertling Karl , Donose Bogdan C. , Brünig Michael , Cernescu Adrian , Govyadinov Alexander A. , Rakić Aleksandar D.
Published: April 2024

Exploring nanoscale material properties through light-matter interactions is essential to unveil new phenomena and manipulate materials at the atomic level, paving the way for ground-breaking advancements in nanotechnology and materials science. Various elementary excitations and low-energy modes of materials reside in the terahertz (THz) range of the electromagnetic spectrum (0.1–10 THz) and occur over various spatial and temporal scales. However, due to the diffraction limit, a slew of THz studies are restricted to drawing conclusions from the spatially varying THz responses around half of the probing wavelengths, i.e., from tens to a couple of hundred micrometers. To address this fundamental challenge, scanning near-field optical microscopy (SNOM), notably scattering-type SNOM (s-SNOM), combined with THz sources has been employed and is fueling growing interest in this technique across multiple disciplines. This review (1) provides an overview of the system developments of SNOM, (2) evaluates current approaches to understand and quantify light-matter interactions, (3) explores advances in THz SNOM applications, especially studies with THz nano-scale spatial responses employing an s-SNOM, and (4) envisions future challenges and potential development avenues for the practical use of THz s-SNOM.
Characterization and calibration of a piezo-energetic composite film as a reactive gauge
Authors: Messer Derek K. , Örnek Metin , Nunes Cohen T. , Paral Mark W. , Son Steven F.
Published: April 2024

The field of multifunctional energetics encompasses a range of materials including propellants, explosives, and pyrotechnics that possess the ability to be manipulated through various characteristics that can be switched between go and no-go, or those that have controllable energy release levels or have additional functions beyond energetic output. The development of multifunctional energetics harnessing electromechanical or piezoelectric properties of polymeric materials or binder systems has garnered increasing interest in recent years. Among polymers, fluoropolymers such as poly(vinylidene fluoride) (PVDF) and copolymers such as poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)], which are used as the binder and oxidizer in the energetic formulations, have demonstrated the highest piezoelectric coefficients. In this study, we fabricated piezo-energetic composite films using aluminum nanopowders (10 wt. % active content) as fuel and P(VDF-TrFE) (70/30) as an oxidizer and investigated the piezoelectric response using a small-scale drop weight setup. Additionally, we employed a shaker setup to investigate the response of the films to vibrations. Our findings demonstrate that these piezo-energetic films can replicate the behavior of a commercial PVDF gauge at relatively low-pressure impacts, indicating their potential use as shock or pressure sensors in various fields, as well as an accelerometer gauge. Additionally, aging studies of up to one year indicated minimal loss in the energetic content of the created films, enabling the use of energetic gauges for an extended period. Our findings support the effectiveness of piezo-energetic composite films as pressure sensors or accelerometers and highlight their potential for energetic applications.
Dynamics of a piezoelectric vibration energy harvester with a pseudoelastic SMA spring
Authors: Adeodato Arthur , Giri Abhijeet M. , Wolszczak Piotr , Litak Grzegorz
Published: April 2024

The development of small-scale and low power consumption devices has been motivating the design of intelligent mechanisms, exhibiting a wide power density spectrum across various external sources. Smart materials come up as an attractive alternative due to their intrinsic multi-coupling between different physical domains. In this context, piezoelectric materials allow conversion of mechanical energy of movement into electrical power through the direct piezoelectric effect. This work investigates a piezoelectric energy harvester combined with a shape memory alloy (SMA) spring to explore the combination of both the smart materials for energy harvesting. The pseudoelastic hysteretic effect of SMA is explored in order to passively change the internal system properties such as stiffness and damping during the harvesting process. Numerical analyses are performed considering the normalized power converted by the harvester, focusing on the influence of the SMA martensite phase transformation under different scenarios. The results exhibit an increment in the harvester bandwidth when compared with a traditional linear piezoelectric energy harvester.
Instability mechanisms of symmetry breaking in the wakes of two anti-phase pitching foils at zero free-stream velocity
Authors: Zhang Zhiyu , Zhang Xing
Published: April 2024

In the present study, we investigate into the symmetry-breaking phenomenon in the wakes produced by two anti-phase pitching foils at zero free-stream velocity. Numerical simulations are performed in a gap ratio range of 0.6≤g≤2.0 and a Reynolds number range of 70≤Re≤200. Six regions are identified in the plane (g, Re), based on distinct symmetry-breaking (or symmetry-preserving) behaviors of the wakes. Floquet stability analysis and dynamic mode decomposition are performed on some selected cases. By means of modal analysis, the behaviors of wakes in different regions are rationalized and the instability mechanisms of symmetry breaking in the unstable regions are unveiled. In addition, the influence of symmetry-breaking instability on propulsive performance is also discussed.
Use of heated grooves for reduction in friction resistance
Authors: Floryan J. M. , Panday S. , Aman S. A.
Published: April 2024

An analysis of the use of heated grooves for resistance reduction was carried out. The model problem consisted of two parallel plates in a relative motion. The stationary plate was equipped with grooves characterized by a sinusoidal pattern and exposed to a pattern of sinusoidal heating. The force required to maintain plate movement was used to judge changes in flow resistance. It was shown that isothermal grooves increase resistance, periodic heating of smooth plate reduces resistance, while periodic heating of grooved plate may either increase or decrease this resistance. The net effect depends on the relative position of the groove and heating patterns, which controls the strength and direction of the pattern interaction effect, and correct selection of this position may eliminate a significant portion of resistance. Increasing groove amplitude and heating intensity reduces resistance similarly to reducing the Prandtl number. The formation of separation bubbles is essential to resistance reduction; an increase in the plate velocity washes these bubbles away, thus eliminating the resistance-reducing effect.
Multi-entropy electrocaloric film induced by three-dimensional thermal conductive ceramic network for synergistic thermal management
Authors: Wang Fang , Wu Wei-Long , Wu Ming , Zhou Dong-Shan , Wang Xiao-Liang , Shen Qun-Dong
Published: April 2024

Imparting high thermal conductivity to electrocaloric refrigeration polymers is a promising solution for efficiently synergizing and accurately managing the vast heat generated by high-power density electronics. We employed a sacrificial template method to construct a three-dimensional thermally conductive SiOC ceramic network and embedded it in the electrocaloric polymer. The electrocaloric composite film with a 1 wt. % SiOC achieved a synergistic improvement in heat transfer and electrocaloric cooling, while the thermal diffusivity of the 10 wt. % composites increased sixfold. The three-dimensional ceramic network not only acted as a heat transfer pathway but also induced the transition of the electrocaloric polymer chain to a high-entropy state, increasing the number of dipole entities that could be driven by the electric field. The system reached a refrigeration temperature change of 2 K at a field strength of as low as 30 MV m−1. The high-entropy and high-crystallized electrocaloric composite film induced by the SiOC thermal conductive interface provides a tool for synergistic thermal management.
Drag coefficient for micron-sized particle in high-speed flows
Authors: Xu Luxi , Ma Likun , Yang Pengnian , Zhao Kangchun , Xia Zhixun , Feng Yunchao
Published: April 2024

The drag force on the small particle in high-speed flows is influenced by the combined effects of fluid viscosity, compressibility, and rarefaction. The existing drag coefficient models are still insufficient in accuracy and efficiency for gas-particle flow simulation. This study comprehensively considers these effects and conducts high-fidelity numerical simulations. A new drag coefficient is generated using a symbolic regression method reasonably based on the particle Mach number, Reynolds number, and Knudsen number, which are related to particle diameter, gas-particle relative velocity, and other parameters. The new drag coefficient possesses clear physical significance, high predictive accuracy, low computational cost, and consistency with theory in limiting conditions. The application of the new drag coefficient to three typical gas-solid two-phase flow cases demonstrated its excellent performance.
Non-coplanar spin structure in a metallic thin film of triangular lattice antiferromagnet CrSe
Authors: Tajima Yusuke , Shiogai Junichi , Ueda Kohei , Suzaki Hirotake , Takaki Kensuke , Seki Takeshi , Kudo Kazutaka , Matsuno Jobu
Published: April 2024

An antiferromagnetic metal with a two-dimensional triangular network offers a unique playground of intriguing magneto-transport properties and functionalities stemming from the interplay between conducting electrons and intricate magnetic phases. A NiAs-type CrSe is one of the candidates owing to alternate stackings of Cr and Se triangular atomic networks in its crystal structure. While the fabrication of CrSe thin films is indispensable to develop functional devices, studies on its thin-film properties have been limited to date due to the lack of metallic samples. Here, we report on the realization of metallic conductivities of CrSe thin films, which allows us to investigate their intrinsic magneto-transport properties. The metallic sample exhibits a co-occurrence of weak ferromagnetism with perpendicular magnetic anisotropy and antiferromagnetic behavior, indicating the presence of non-coplanar spin structures. In addition, control of the polarity and tilting angle of the non-coplanar spin structure is accomplished by a sign of cooling magnetic fields. The observed non-coplanar spin structure, which can be a source of emergent magnetic field acting on the conducting electrons, highlights the high potential of the triangular lattice antiferromagnet and provides a unique platform for functional thin-film devices composed of NiAs-type derivative Cr chalcogenides and pnictides.
Effects of a spanwise magnetic field on the exact coherent states in a channel flow
Authors: Li Sen , Shi Xiaomeng , Wang Lebing , Dong Shuai
Published: April 2024

The primary objective of this study is to examine the effect of a uniformly constant spanwise magnetic field on exact coherent states and their structures in channel flow. Exact coherent states represent nonlinear solutions to the Navier–Stokes equations, bearing significant importance in the prediction and control of flow with and without magnetic field. Despite the recent extensive research which have reported the influences of magnetic fields with respect to fluid dynamics, the specific effect of a spanwise magnetic field on the exact coherent states remain ambiguous. To investigate the influence of magnetic field on exact coherent states in channel flow, our study encompasses Reynolds numbers ranging from 3000 to 10 000, with variations in the size of computational domains. High-precision direct numerical simulations, coupled with a Fourier–Chebyshev spatial pseudospectra discretization, are employed to solve the governing equations under the assumption of low magnetic Reynolds number. Starting from laminar flow, we utilize a bisection method on the amplitude of perturbations to track the exact coherent states in the channel. In a smaller computational domain 2π × 2.4 × 2, the spanwise magnetic field expedites the self-sustaining process of exact coherent structures, accelerating the transition from streamwise vortices to streamwise streaks. In a larger computational domain, the exact coherent states are bifurcated from relative periodic orbit solutions to traveling wave solutions. Furthermore, as the spanwise computational domain expands, localization coherent structures persist and steadily propagate downstream in the channel.
Early-onset of pressure-induced metallization in iron-doped multilayered molybdenum disulfide
Authors: Lin Chih-Ming , Lin Der-Yuh , Juang Jenh-Yih , Huang Tony , Zhang Dong-Zhou , Tsai Yi-Jia , Jian Sheng-Rui , Kim Joon-Seok , Lin Jung-Fu
Published: April 2024

Chemical doping-induced magnetism in semiconducting transition metal dichalcogenides (TMDC) can have significant implications in electrically controlled spintronics. In addition, strain engineering of the layered structures of TMDCs can further allow for tuning the interlayer van der Waals (vdW) bonds and controlling their electronic properties. Of particular interest are the effects of Fe doping coupled with strain tuning on the vdW bonds and associated electronic properties of Fe:MoS2. Here, we have investigated compressive strain tuning effects on the structural and vibrational properties of Fe:MoS2 using in situ angle-dispersive x-ray diffraction and Raman scattering spectroscopy at quasi-hydrostatic pressures up to 25.0(1) GPa. Our results indicate that Fe:MoS2 undergoes isostructural electronic transitions similar to those in pristine MoS2, but at significantly lower pressures. Sudden changes in the microscopic strain, Raman peak splitting, and phonon softening are observed at the transition pressures, suggesting that the structural instability introduced by the Fe dopants is responsible for the early onset of the transitions. The significant effects of Fe dopants on the interlayer vdW bonding, as well as the structural and phononic properties under compressive strain indicate a strategy for modulating the electronic and ferromagnetic properties of TMDCs.
First-principles definition of ionicity and covalency in molecules and solids
Authors: Anisimov Vladimir I. , Oganov Artem R. , Korotin Dmitry M. , Novoselov Dmitry Y. , Shorikov Alexey O. , Belozerov Alexander S.
Published: April 2024

The notions of ionicity and covalency of chemical bonds, effective atomic charges, and decomposition of the cohesive energy into ionic and covalent terms are fundamental yet elusive. For example, different approaches give different values of atomic charges. Pursuing the goal of formulating a universal approach based on firm physical grounds (first-principles or non-empirical), we develop a formalism based on Wannier functions with atomic orbital symmetry and capable of defining these notions and giving numerically robust results that are in excellent agreement with traditional chemical thinking. Unexpectedly, in diamond-like boron phosphide (BP), we find charges of +0.68 on phosphorus and −0.68 on boron atoms, and this anomaly is explained by the Zintl–Klemm nature of this compound. We present a simple model that includes energies of the highest occupied cationic and lowest unoccupied anionic atomic orbitals, coordination numbers, and strength of interatomic orbital overlap. This model captures the essential physics of bonding and accurately reproduces all our results, including anomalous BP.