bluuebunny/crossref_metadata_2025 huggingface dataset:
Quick-connect scanning tunneling microscope head with nested piezoelectric coarse walkers
Authors: Coe Angela M. , Li Guohong , Andrei Eva Y.
Published: July 2024

To meet changing research demands, new scanning tunneling microscope (STM) features must constantly evolve. We describe the design, development, and performance of a modular plug-in STM, which is compact and stable. The STM head is equipped with a quick-connect socket that is matched to a universal connector plug, enabling it to be transferred between systems. This head can be introduced into a vacuum system via a load-lock and transferred to various sites equipped with the connector plug, permitting multi-site STM operation. Its design allows for reliable operation in a variety of experimental conditions, including a broad temperature range, ultra-high vacuum, high magnetic fields, and closed-cycle pulse-tube cooling. The STM’s compact size is achieved by a novel nested piezoelectric coarse walker design, which allows for large orthogonal travel in the X, Y, and Z directions, ideal for studying both bulk and thin film samples ranging in size from mm to μm. Its stability and noise tolerance are demonstrated by achieving atomic resolution under ambient conditions on a laboratory desktop with no vibrational or acoustic isolation. The operation of the nested coarse walkers is demonstrated by successful navigation to a μm-sized 2D sample.
Optimization of excitation field depending on magnetic nanoparticle parameters for magnetic hyperthermia under safety constraint
Authors: Yoshida Takashi , Enpuku Keiji
Published: July 2024

Hysteresis loss (P) of magnetic nanoparticles (MNPs) under alternating current excitation has been used to induce hyperthermia in cancer cells. We theoretically optimized the excitation field amplitude Hac and frequency f required to maximize P, while the product C = Hacf did not exceed a threshold value to avoid side effects in biomedical applications. We obtained analytical expressions for the optimum values of Hac and f as functions of C and MNP parameters. Almost the same P could be obtained for MNPs with magnetic core diameters dc ranging over 20–40 nm if Hac and f were optimized according to the dc value. A numerical example was a P of ∼0.4 kW/g Fe for immobilized MNPs under C = 2 × 109 A/(ms). We also examined the dependences of P on MNP parameters under the optimum excitation field. A large saturation magnetization was essential for a large P. The degradation of P caused by the dc distribution in a practical (realistic) sample was examined, and the conditions that reduce degradation were determined. There was a strong agreement among these properties between the analyses and numerical simulations. Finally, we showed how much P increased for suspended MNPs relative to that for immobilized MNPs. Overall, these results will be useful for the development of high-performance hyperthermia systems.
Differentiating contribution of electron–phonon coupling to the thermal boundary conductance of metal–metal–dielectric systems
Authors: Meng Biwei , Yuan Chao
Published: July 2024

Electron–phonon coupling thermal resistance in metals is a key factor affecting the thermal boundary conductance (TBC) of metal–metal–dielectric systems. However, quantitatively differentiating the contribution of electron–phonon coupling to TBC is still a challenge, as various thermal resistances are coupled in a complicated manner at the metal–metal–dielectric interface. Herein, we propose a two-step strategy to study electron–phonon coupling. We first decouple the phonon–phonon thermal conductance (TBCp-p) between metallic interlayer and dielectric from the metal–metal–dielectric interface by experimentally characterizing the TBCp-p of a single metallic interlayer deposited dielectric with the transient thermoreflectance technique; Combining metal–metal–dielectric TBC measurement and a thermal circuit model with measured TBCp-p as input, the contribution of electron–phonon coupling to TBC of the metal–metal–dielectric system is differentiated quantitatively. For the Au–Ni–GaN system, the contribution of electron–phonon coupling thermal resistance in the Ni interlayer (Re−ph,Ni) is substantially higher at lower Ni interlayer thickness, reaching 35% at ∼1 nm Ni. The electron–phonon coupling constant of Ni (gNi) was fitted in the range of 6.4 × 1016–36 × 1016 W/m3K. The above results were also verified in the Au–Ni–SiC system. This study will promote a deeper understanding of the thermal transport in the metal–metal–dielectric system and provide an insightful indication for the manipulation of TBC in this system.
Ventilation performance study of a high-speed train cabin based on displacement ventilation and mixed ventilation
Authors: Wu Songbo , Li Tian , Zhang Jiye
Published: July 2024

Indoor ventilation systems play an important role in controlling energy consumption, thermal comfort, and airborne pollutants. This work is concerned with whether the combination of displacement and mixed ventilation can overcome these systems' respective shortcomings to improve the ventilation performance of high-speed train cabins. This work is based on computational fluid dynamics. The results show that when more fresh airflow enters the compartment from the top vents, the flow field is mainly driven by mechanical forces, and two vortices are formed. When more fresh airflow enters the compartment from the bottom vents, the flow field is mainly driven by thermal buoyancy. Meanwhile, the airflow mainly spreads upward, with lower cooling energy consumption, lower wind speed, higher ventilation efficiency, and smaller longitudinal diffusion of pollutants, but increased temperature difference. When the ratio of top and bottom supply air flow is 75%/25%, thermal comfort can be improved, while balancing energy consumption and air quality. If there was a disease outbreak, the flow rate of the bottom air supply could be increased appropriately. To further improve the ventilation performance, on the one hand, it is necessary to appropriately increase the temperature of the bottom air supply, and on the other hand, it is necessary to avoid short-circuiting of the airflow, due to the lack of synergy between thermal buoyancy and mechanical force. The results of the study can provide a reference for safeguarding passengers and improving the ventilation design of high-speed trains.
Hot electron effect in high-order harmonic generation from graphene driven by elliptically polarized light
Authors: Nakagawa Kotaro , Mao Wenwen , Sato Shunsuke A. , Ago Hiroki , Rubio Angel , Kanemitsu Yoshihiko , Hirori Hideki
Published: July 2024

We studied high-order harmonic generation (HHG) in graphene driven by either linearly or elliptically polarized mid-infrared (MIR) light, and we additionally applied terahertz (THz) pulses to modulate the electron distribution in graphene. The high-harmonic spectrum obtained using linearly polarized MIR light contains only odd-order harmonics. We found that the intensities of the fifth- and seventh-order harmonics are reduced by the modulation with the THz pulses. In addition, we found that the THz-induced reduction of the seventh-order harmonic driven by elliptically polarized MIR light (at ellipticity ε = 0.3) is larger than that of seventh-order harmonic driven by linearly polarized MIR light (ε = 0). The observed behavior can be reproduced by theoretical calculations that consider different electron temperatures (caused by the THz pulses). Furthermore, the observed stronger suppression of HHG driven by elliptically polarized light reveals the following: in the case of elliptically polarized light, the generation of harmonics via interband transitions to conduction-band states that are closer to the Dirac point is more important than in the case of linearly polarized light. In other words, the quantum pathways via interband transitions to low-energy states are the origin of the enhancement of HHG that can be achieved in graphene by using elliptically polarized light.
InAlGaN-based HEMT with very low Ohmic contact resistance regrown at 850 °C by MOVPE
Authors: Pitaval Charles , Aroulanda Sébastien , Fouzi Yassine , Defrance Nicolas , Lacam Cédric , Michel Nicolas , El Bondry Nadia , Oualli Mourad , Teisseire Laurent , Jacquet Jean-Claude , Piotrowicz Stéphane , Gaquiere Christophe , Delage Sylvain L.
Published: July 2024

Regrown Ohmic contacts have been widely studied for high millimeter-wave applications. However, few were applied to InAl(Ga)N-based HEMT despite the lattice match benefits with GaN channel because of the poor thermal stability of the quaternary barrier. In this article, we use relatively low temperature (850 °C) MOVPE technique for the regrowth of heavily Si doped GaN (1 × 1020 cm−3) to avoid deterioration of the channel's electrical characteristics. Moreover, high selectivity of the regrowth is obtained, thanks to large opening ratio of the hard mask. The state-of-the-art total Ohmic contact resistance Rc = 0.06 Ω mm is reached with high homogeneity on a 4-in. wafer. This result reflects the combined contribution of the doped GaN interfaces with both the metal contact and the channel. 2 × 50 μm transistors featuring 100 nm gate length with regrown Ohmic contacts present remarkable improvements of DC and RF performances. At 40 GHz, the highest Power Added Efficiency (PAE) of 54% is attained at an output power of 3.8 W mm−1, while the maximum output power of 9.4 W mm−1 is achieved at a PAE of 48%, corresponding to bias voltages of 15 and 30 V, respectively.
Enhanced thermoelectric performance of MoSe2 under high pressure and high temperature by suppressing bipolar effect
Authors: Wang Dianzhen , You Cun , Ge Yufei , Wang Fei , Wang Xinglin , Liang Xiao , Zhou Qiang , Tao Qiang , Chen Yanli , Zhu Pinwen
Published: July 2024

The electrical transport property of layered MoSe2 has a strong response to high pressure by enhancing the inter-layer interaction. However, the narrowed bandgap under high pressure will cause the bipolar effect (i.e., the thermally excited minority carriers contribute to a Seebeck coefficient with the opposite sign to the majority carriers) at high temperatures to degrade the thermoelectric (TE) performance. Hence, suppressing the bipolar effect is important to optimize the TE performance of MoSe2 under high pressure and high temperature (HPHT). In this study, the degradation of TE performance caused by the bipolar effect under HPHT in MoSe2 is investigated. It is found that in MoSe2, the electrical conductivity was improved significantly by pressure; however, the bipolar effect led to a significantly degraded Seebeck coefficient at high temperatures. By injecting massive carriers beforehand, the bipolar effect was suppressed to make a dominant type of p-type charge carries, achieving an increased Seebeck coefficient with increasing temperature, resulting in an improved power factor from 29.3 μW m−1 K−2 in MoSe2 to 285.7 μW m−1 K−2 in Mo0.98Nb0.02Se2 at 5.5 GPa, 1110 K. Combined with the reduced thermal conductivity by point defect scattering on phonons, a maximum ZT value of 0.11 at 5.5 GPa, 1110 K. This work highlights the significance of suppressing the bipolar effect under HPHT for optimizing TE performance in such layered semiconductors.
Tribological modifications of water flow at liquid–solid interface by nanobubbles
Authors: Kishimoto Takao , Kioka Arata , Nakagawa Masami , Mehrizi Abbasali Abouei
Published: July 2024

Previous studies investigated on friction reduction at the solid–liquid interface due to the presence of metal nanoparticles and fine bubbles such as microbubbles. This paper experimentally investigated how nanobubbles (ultrafine bubbles) change the tribological nature of water flow at the solid–liquid interface. We flowed air nanobubbles-containing water into a cylindrical cell filled with soda-lime glass, alumina, and high-carbon chromium-bearing steel beads. We then estimated the changes in the ratio of Darcy's friction factor of nanobubbles-containing water flow (fnb) to that of water flow before injecting nanobubbles (fref) with the time of injecting nanobubbles. We found that nanobubbles are capable of reducing the friction in water flow running through the soda glass beads, accounting for up to 6.1% reduction in terms of Darcy's friction factor ratio (fnb/fref) in our experiment. The magnitude of friction reduction by nanobubbles can be greater with a larger total surface area where surface nanobubbles are present. In contrast, nanobubbles encouraged enhancement of the friction of water flow within the high-carbon chromium-bearing steel beads, showing 3.8% enhancement in the friction factor ratio (fnb/fref). The results indicate that nanobubbles play a role in the friction reduction of water flow when the surface of the bead material is rougher than the size of nanobubbles, while nanobubbles enhance the friction of water flow when the bead surface is smooth enough. Therefore, nanobubbles can be a green nanoscopic additive for modifying the friction and lubrication performance of water flow depending on the surface roughness of the flow material.
Application of triboelectric nanogenerator in self-powered motion detection devices: A review
Authors: Jiang Hongyuan , Lv Xin , Wang Kai
Published: July 2024

Among today’s bustling lifestyles, the demand for autonomous, durable, and low-maintenance healthcare systems has surged, surpassing that of earlier periods. Nanostructured and environmentally friendly materials employed in nanogenerator technology offer a novel avenue for biomedical applications by harnessing biomechanical energy. Triboelectric Nanogenerators (TENGs) have emerged as comprehensive solutions, furnishing self-sustaining, eco-conscious, and compact devices. Recognizing the immense potential of TENGs, this paper presents a comprehensive overview of its motion detection. Our analysis delves into the versatility of TENG-based motion detection systems, providing wearable, user-friendly solutions powered by human motion. Recent advancements in triboelectric devices are cataloged, elucidating their structural intricacies, capabilities, performance metrics, and future prospects. In addition, the article also outlines the applications of different TENGs in motion monitoring, including contact, non-contact, and single-electrode mode. The evolution of intelligent wearable technologies has extended our capacities in communication, healthcare, and various other domains beyond our biological limits. Apart from the Internet of Things, the concept of Internet of bodies or beings is poised for rapid advancement, promising further transformation of our lifestyles. Conclusively, we present insights into forthcoming opportunities and plausible strategies to address anticipated hurdles.
Prescribed fire increases forage mineral content in grazed rangeland
Authors: Wanchuk Megan R. , McGranahan Devan Allen , Sedivec Kevin K. , Swanson Kendall C. , Hovick Torre J.
Published: July 2024

Background Sustainable rangeland management balances production and conservation. While a broad literature describesthe conservation benefits of prescribed fire, benefits for livestock production have emerged more slowly. Mineral nutrition is important for livestock health and performance, but the impact of prescribed fire on mineral concentration of forages, especially in the northern US Great Plains, remains unknown. Aims We investigated how burning affects the mineral concentration of forage early and late in the growing season. Methods Data were collected on mixed-grass prairie in south-central North Dakota, USA. Vegetation was clipped from recently burned, 1 year post-fire, 2 years post-fire, and not-yet-burned patches at the same sampling points in spring and late summer. Samples were analysed for calcium, phosphorus, magnesium, potassium, copper, iron, manganese, and zinc concentration. Key results Burning increased forage mineral concentration across most minerals. Phosphorous, potassium, copper and zinc were higher in burned areas in late spring and summer; calcium, magnesium and manganese were only higher during the late summer; Late-season iron levels increased with time since fire. Conclusions Prescribed fire has a positive effect on forage mineral content. Implications Prescribed fire has the potential to reduce mineral supplementation costs and improve cow performance.
An alternative to the Euler equation of rigid body rotational dynamics
Authors: Fariborz Amir H
Published: July 2024

The Euler equation provides a convenient framework for studying the rotational dynamics of rigid bodies in solid mechanics. While this equation is written from the point of view of an inertial observer, it is implemented in a non-inertial ancillary coordinate system attached to the rigid body and the equations of the rotation are consequently expressed in this ancillary system. We examine how the rotational dynamics of rigid bodies can be described by the inertial observer directly in the inertial coordinate system (instead of employing an ancillary non-inertial frame), and derive the differential equations of the rotation in this inertial system. This approach can have advantages in situations where the rigid body has both translational motion in addition to rotational motion.
Consideration of the effect of nanoscale porosity on mass transport phenomena in PECVD coatings
Authors: Franke J , Zysk F , Wilski S , Liedke M O , Butterling M , Attallah A G , Wagner A , Kühne T D , Dahlmann R
Published: July 2024

Here we show a novel approach to characterize the gas transfer behavior of silicon-oxide (SiO
x
) coatings and explain the underlying dynamics. For this, we investigate the coating on a nm-scale both by measurement and simulation. Positron annihilation spectroscopy (PAS) and quantum mechanical electronic structure-based molecular dynamics simulations are combined to characterize the porous landscape of SiO
x
coatings. This approach analyses the influence of micropores smaller than 2 nm in diameter on gas permeation which are difficult to study with conventional methods. We lay out the main pore diameter ranges and their associated porosity estimates. An influence of layer growth on pore size and porosity was found, with an increased energy input during layer deposition leading to smaller pore sizes and a reduced porosity. The molecular dynamics simulations quantify the self-diffusion of oxygen and water vapor through those PAS deducted micropore ranges for hydrophilic and hydrophobic systems. The theoretical pore size ranges are fitting to our PAS results and complete them by giving diffusion coefficients. This approach enables detailed analysis of pore morphology on mass transport through thin film coatings and characterization of their barrier or membrane performance. This is a crucial prerequisite for the development of an exhaustive model of pore dominated mass transports in PECVD coatings.
Study on the noise reduction mechanism and application of the noise simulation analysis of care robots
Authors: Tang Yaochi , Chen Yi Ting
Published: July 2024

Currently, robots on the market have varying operational requirements due to their different functions. The care robots are primarily used to serve people under care. Therefore, reducing the amount of noise they make while moving is important. This study measured their noise in an anechoic room. This study found that the most noise is produced when they move forward and backward at full speed. The robot’s vibration signal was measured and compared with the noise source to propose the most effective way to reduce the noise. Due to the robot’s small internal space, methods for noise reduction are limited. The care robot’s development must adopt quick customizable 3D printing technologies, produce sound absorption/insulation materials independently, determine the best sound absorption/insulation material and structural configuration, use impedance tubes to measure the sound absorption coefficient and sound insulation performance, and select the appropriate materials and implement them into the robot for actual tests. These results indicate that the noise value of the main contributing frequency can be reduced by 15 dB at most. Furthermore, this study also used an acoustic simulation analysis to calculate and simulate the vibration and noise of the care robot. The vibration and noise signals during the robot’s operation were measured and compared to provide a reference for manufacturers in design. Finally, experimental materials were added to the simulation and compared with the noise reduction results. The results show similar trends. Therefore, the model developed in this study may provide a fast, low-cost, and feasible method for the noise reduction of care robots.
In-situ monitoring of the small changes in process parameters with multi-sensor fusion during LPBF
Authors: Cao Longchao , Guo Wentao , He Binyan , Li Weihong , Huang Xufeng , Zhang Yahui , Cai Wang , Zhou Qi
Published: July 2024

The small changes in process parameters have significant influences on the stability of laser powder bed fusion (LPBF). Therefore, monitoring the small changes in process parameters is particularly important. This paper proposed a machine learning (ML)-based multi-sensor fusion approach to monitor the LPBF processing state by combining photodiode, acoustic, and visual signals. In order to extract the motion features of the melt pool more accurately and describe its transient changes, an ellipse adjustment algorithm is proposed to segment the melt pool images, eliminating the interference of spatters. The motion features combined with preprocessed acoustic signals and photodiode signals to identify melting states during small changes in process parameters. The proposed ML-based multi-sensor fusion approach achieves impressive prediction accuracies of 99.9% for identifying the fluctuations in the process parameters. The results demonstrate that the proposed method can accurately identify small changes in process parameters, which is of great significance for improving the process stability and providing reliable guidance in subsequent work.
Rolling bearing fault diagnosis method based on PE-DCM and ViT
Authors: Hui Yongyong , Xu Ke , Chen Peng , Zhao Xiaoqiang
Published: July 2024

Considering the issue of capturing the local and global contextual information and enhancing the parallel capability of bearing fault diagnosis in variable load and noise environments, a fault diagnosis method of rolling bearing based on PE-DCM and Vision Transformer (ViT) is proposed. Firstly, the one-dimensional vibration signal is converted into a two-dimensional time-frequency diagram by continuous wavelet transform in the data processing module, and the model can understand the characteristics of the vibration signal more comprehensively. Secondly, a pyramid exponential expansion convolution module is established to extract the local features of fault information. Then, the global features of the fault information are learned through the ViT network, and the adaptive multi-attention is used to dynamically adjust the attention weights according to the features of the input data so as to inhibit noise or unimportant information. Finally, the experimental verification is carried out by using Case Western Reserve University and self-made MFS-bearing data set. The experimental results show that the method can better reflect the powerful image classification ability of the ViT network and has better noise resistance and generalization compared with other fault diagnosis methods.
Efficient photoanode with a MoS2/TiO2/Au nanoparticle heterostructure for ultraviolet-visible photoelectrocatalysis
Authors: Mai The-Hung , Do Huy-Binh , Pham Long Duy , Phan Thien Xuan , Chen Wei-Zhi , Lan Liang-Wei , Lin Hung-Ju , Nguyen Van-Hung , Dong Chung-Li , Kumar Alagarsamy S K , El-Mahdy Ahmed F M , Lee Hyeonseok , Dang Dinh Khoi , Vo Dai-Viet N , Tu Li-Wei , Kuo Chien-Cheng , Yang Hung-Duen , Pham Phuong V
Published: July 2024

Green energy technology is generally becoming one of hot issues that need to be solved due to the adverse effects on the environment of fossil fuels. One of the strategies being studied and developed by theorists and experimentalists is the use of photoelectrochemical (PEC) cells, which are emerging as a candidate to produce hydrogen from water splitting. However, creating photoelectrodes that meet the requirements for PEC water splitting has emerged as the primary obstacle in bringing this technology to commercial fruition. Here, we construct a heterostructure, which consists of MoS2/TiO2/Au nanoparticles (NPs) to overcome the drawbacks of the photoanode. Owing to the dependence on charge transfer, the bandgap of MoS2/TiO2 and the utilization the Au NPs as a stimulant for charges separation of TiO2 by localized surface plasmon resonances effect as well as the increase of hot electron injection to cathode, leading to photocatalytic activities are improved. The results have recorded a significant increase in the photocurrent density from 2.3

μ

A

c

m

−
2

of TiO2 to approximately 16.3

μ

A

c

m

−
2

of MoS2/TiO2/Au NPs. This work unveils a promising route to enhance the visible light adsorption and charge transfer in photo-electrode of the PEC cells by combining two-dimensional materials with metal NPs.
Clinical applicability of Linac-integrated CBCT based NIPAM 3D dosimetry: a dual-institutional investigation
Authors: Kunkyab Tenzin , Lakrad Kawtar , Jirasek Andrew , Oldham Mark , Quinn Benjamin , Hyde Derek , Adamson Justus
Published: July 2024

Objective. To develop and benchmark a novel 3D dose verification technique consisting of polymer gel dosimetry (PGD) with cone-beam-CT (CBCT) readout through a two-institution study. The technique has potential for wide and robust applicability through reliance on CBCT readout. Approach. Three treatment plans (3-field, TG119-C-shape spine, 4-target SRS) were created by two independent institutions (Institutions A and B). A Varian Truebeam linear accelerator was used to deliver the plans to NIPAM polymer gel dosimeters produced at both institutions using an identical approach. For readout, a slow CBCT scan mode was used to acquire pre- and post-irradiation images of the gel (1 mm slice thickness). Independent gel analysis tools were used to process the PGD images (A: VistaAce software, B: in-house MATLAB code). Comparing planned and measured doses, the analysis involved a combination of 1D line profiles, 2D contour plots, and 3D global gamma maps (criteria ranging between 2%1 mm and 5%2 mm, with a 10% dose threshold). Main results. For all gamma criteria tested, the 3D gamma pass rates were all above 90% for 3-field and 88% for the SRS plan. For the C-shape spine plan, we benchmarked our 2% 2 mm result against previously published work using film analysis (93.4%). For 2%2 mm, 99.4% (Institution A data), and 89.7% (Institution B data) were obtained based on VistaAce software analysis, 83.7% (Institution A data), and 82.9% (Institution B data) based on MATLAB. Significance. The benchmark data demonstrate that when two institutions follow the same rigorous procedures gamma passing rates up to 99%, for 2%2 mm criteria can be achieved for substantively different treatment plans. The use of different software and calibration techniques may have contributed to the variation in the 3D gamma results. By sharing the data across institutions, we observe the gamma passing rate is more consistent within each pipeline, indicating the need for standardized analysis methods.
Functional nanotransducer-mediated wireless neural modulation techniques
Authors: Li Galong , Li Dongyan , Lan Bin , Chen Yihuan , Zhang Wenli , Li Baojuan , Liu Yang , Fan Haiming , Lu Hongbin
Published: July 2024

Functional nanomaterials have emerged as versatile nanotransducers for wireless neural modulation because of their minimal invasion and high spatiotemporal resolution. The nanotransducers can convert external excitation sources (e.g. NIR light, x-rays, and magnetic fields) to visible light (or local heat) to activate optogenetic opsins and thermosensitive ion channels for neuromodulation. The present review provides insights into the fundamentals of the mostly used functional nanomaterials in wireless neuromodulation including upconversion nanoparticles, nanoscintillators, and magnetic nanoparticles. We further discussed the recent developments in design strategies of functional nanomaterials with enhanced energy conversion performance that have greatly expanded the field of neuromodulation. We summarized the applications of functional nanomaterials-mediated wireless neuromodulation techniques, including exciting/silencing neurons, modulating brain activity, controlling motor behaviors, and regulating peripheral organ function in mice. Finally, we discussed some key considerations in functional nanotransducer-mediated wireless neuromodulation along with the current challenges and future directions.
Head and neck tumor segmentation from [18F]F-FDG PET/CT images based on 3D diffusion model
Authors: Dong Yafei , Gong Kuang
Published: July 2024

Objective. Head and neck (H&N) cancers are among the most prevalent types of cancer worldwide, and [18F]F-FDG PET/CT is widely used for H&N cancer management. Recently, the diffusion model has demonstrated remarkable performance in various image-generation tasks. In this work, we proposed a 3D diffusion model to accurately perform H&N tumor segmentation from 3D PET and CT volumes. Approach. The 3D diffusion model was developed considering the 3D nature of PET and CT images acquired. During the reverse process, the model utilized a 3D UNet structure and took the concatenation of 3D PET, CT, and Gaussian noise volumes as the network input to generate the tumor mask. Experiments based on the HECKTOR challenge dataset were conducted to evaluate the effectiveness of the proposed diffusion model. Several state-of-the-art techniques based on U-Net and Transformer structures were adopted as the reference methods. Benefits of employing both PET and CT as the network input, as well as further extending the diffusion model from 2D to 3D, were investigated based on various quantitative metrics and qualitative results. Main results. Results showed that the proposed 3D diffusion model could generate more accurate segmentation results compared with other methods (mean Dice of 0.739 compared to less than 0.726 for other methods). Compared to the diffusion model in 2D form, the proposed 3D model yielded superior results (mean Dice of 0.739 compared to 0.669). Our experiments also highlighted the advantage of utilizing dual-modality PET and CT data over only single-modality data for H&N tumor segmentation (with mean Dice less than 0.570). Significance. This work demonstrated the effectiveness of the proposed 3D diffusion model in generating more accurate H&N tumor segmentation masks compared to the other reference methods.
Hysteresis in radio frequency capacitively coupled CF4 plasmas
Authors: Wang Xiao-Kun , Korolov Ihor , Wilczek Sebastian , Masheyeva Ranna , Liu Yong-Xin , Song Yuan-Hong , Hartmann Peter , Donkó Zoltán , Schulze Julian
Published: July 2024

Based on experiments and simulations, various plasma parameters are found to undergo a hysteresis as a function of the driving voltage amplitude in capacitively coupled CF4 discharges. Phase Resolved Optical Emission Spectroscopy reveals that the discharge operates in a hybrid combination of the drift-ambipolar and α-mode at low voltage. In this mode, the electric field and mean electron energy are high in the electronegative plasma bulk region. As the cross section for electron attachment is appreciable only at high electron energies, this mode results in strong negative ion production and keeps the electron density low as well as the mode of plasma operation stable, when the voltage is increased moderately. Increasing the driving voltage amplitude further ultimately induces a mode transition into a pure α-mode, once the electron density increases strongly. Decreasing the voltage again results in a reverse mode transition at a lower voltage compared to the previous mode transition, because the electron density is now initially high in the bulk and, thus, the bulk electric field and mean electron energy are low resulting in inefficient generation of negative ions via electron attachment. This keeps the electron density high even at lower driving voltages. This effect leads to the emergence of two steady states of plasma operation within a certain voltage range. The different electron energy distribution functions in these two states result in markedly different generation and density profiles of F atoms, with higher values occurring in the increasing voltage branch of the hysteresis. The ion flux and mean energy at the electrodes also differ. The voltage range, where the hysteresis occurs, is affected by the ion induced secondary electron coefficient (γ). A larger value of γ results in a shift of the hysteresis voltage range towards lower values.
Homotopy, symmetry, and non-Hermitian band topology
Authors: Yang Kang , Li Zhi , König J Lukas K , Rødland Lukas , Stålhammar Marcus , Bergholtz Emil J
Published: July 2024

Non-Hermitian matrices are ubiquitous in the description of nature ranging from classical dissipative systems, including optical, electrical, and mechanical metamaterials, to scattering of waves and open quantum many-body systems. Seminal line-gap and point-gap classifications of non-Hermitian systems using K-theory have deepened the understanding of many physical phenomena. However, ample systems remain beyond this description; reference points and lines do not in general distinguish whether multiple non-Hermitian bands exhibit intriguing exceptional points, spectral braids and crossings. To address this we consider two different notions: non-Hermitian band gaps and separation gaps that crucially encompass a broad class of multi-band scenarios, enabling the description of generic band structures with symmetries. With these concepts, we provide a unified and comprehensive classification of both gapped and nodal systems in the presence of physically relevant parity-time (

PT

) and pseudo-Hermitian symmetries using homotopy theory. This uncovers new stable topology stemming from both eigenvalues and wave functions, and remarkably also implies distinct fragile topological phases. In particular, we reveal different Abelian and non-Abelian phases in

PT

-symmetric systems, described by frame and braid topology. The corresponding invariants are robust to symmetry-preserving perturbations that do not induce (exceptional) degeneracy, and they also predict the deformation rules of nodal phases. We further demonstrate that spontaneous

PT

symmetry breaking is captured by Chern–Euler and Chern–Stiefel–Whitney descriptions, a fingerprint of unprecedented non-Hermitian topology previously overlooked. These results open the door for theoretical and experimental exploration of a rich variety of novel topological phenomena in a wide range of physical platforms.
Optimal multiple-phase estimation with multi-mode NOON states against photon loss
Authors: Namkung Min , Kim Dong-Hyun , Hong Seongjin , Kim Yong-Su , Lee Changhyoup , Lim Hyang-Tag
Published: July 2024

Multi-mode NOON states can quantum-enhance multiple-phase estimation in the absence of photon loss. However, a multi-mode NOON state is known to be vulnerable to photon loss, and its quantum-enhancement can be dissipated by lossy environment. In this work, we demonstrate that a quantum advantage in estimate precision can still be achieved in the presence of photon loss. This is accomplished by optimizing the weights of the multi-mode NOON states according to photon loss rates in the multiple modes, including the reference mode which defines the other phases. For practical relevance, we also show that photon-number counting via a multi-mode beam-splitter achieves the useful, albeit sub-optimal, quantum advantage. We expect this work to provide valuable guidance for developing quantum-enhanced multiple-phase estimation techniques in lossy environments.
Quantum-enhanced joint estimation of phase and phase diffusion
Authors: Jayakumar Jayanth , Mycroft Monika E , Barbieri Marco , Stobińska Magdalena
Published: July 2024

Accurate phase estimation in the presence of unknown phase diffusive noise is a crucial yet challenging task in noisy quantum metrology. This problem is particularly interesting due to the detrimental impact of the associated noise. Here, we investigate the joint estimation of phase and phase diffusion using generalized Holland–Burnett states, known for their experimental accessibility. These states provide performance close to the optimal state in single-parameter phase estimation, even in the presence of photon losses. We adopt a twofold approach by analyzing the joint information extraction through the double homodyne measurement and the joint information availability across all probe states. Through our analysis, we find that the highest sensitivities are obtained by using states created by directing all input photons into one port of a balanced beam splitter. Furthermore, we infer that good levels of sensitivity persist even in the presence of moderate photon losses, illustrating the remarkable resilience of our probe states under lossy conditions.
Electromagnetically induced transparency with magnetically induced

Δ
F
=
0
,

m
F

=
0
→

m
F

=
0

probe transition
Authors: Sargsyan Armen , Sarkisyan David , Papoyan Aram
Published: July 2024

Interest in magnetically induced (MI) transitions of alkali metal atoms is caused by the fact that their intensities can exceed the intensities of ‘regular’ atomic transitions in a wide magnetic field range (200–4000 G). The goal of this work was to form and study, for the first time, electromagnetically induced transparency (EIT) resonance in a strong magnetic field using probe radiation tuned to

|

F

g

=
F
,

m
F

=
0
⟩
→

|

F

e

=
F
,

m
F

=
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MI transition, which is forbidden in zero magnetic fields. Two narrow-band linearly polarized cw diode lasers were used to form EIT resonance on a Λ-type system of a Cs atomic D2 line in a strong transverse magnetic field (up to 1000 G). The resonance was formed in a Cs atomic vapor nanocell with an atomic vapor column thickness of 850 nm.
Measurements of laser-plasma instabilities in double-cone ignition experiments relevant to the direct-drive conditions at Shenguang-II Upgrade laser facility
Authors: Zhao X. , Yuan X.H. , Dong Y.F. , Glize K. , Zhang Y.H. , Zheng J. , Xing C.Q. , Gu H.C. , Zhang C.L. , Dai Y. , Fang K. , Zhang Z. , Yan R. , Wu F.Y. , Zhang J.
Published: July 2024

Experiments have been performed to investigate laser-plasma instabilities (LPIs) relevant to the direct-drive inertial confinement fusion (ICF) conditions at the Shenguang-II Upgrade (SG-II UP) laser facility during the double-cone ignition (DCI) experimental campaigns, with the overlapped laser intensity ranging from

6
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10

14

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c

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to

1.8
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10

15

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c

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. An overall LPI scenario has been built from the collection and investigation of angularly distributed scattered light. Across broad ranges of laser and plasma parameters, relevant to the direct-drive ICF conditions, the dominance of the stimulated Raman side scattering (SRSS) was confirmed, and its coexistence with the two-plasmon decay (TPD) was also observed. Significant SRSS scattered light was observed across an extremely wide range of emission angles, concentrated at large angles, and demonstrated to be robust throughout the parameter space. Time-resolved spectral measurements show distinctly different SRSS behaviors along different angles and a slightly higher threshold compared to the TPD. The overall SRSS energy loss was measured, indicating a scattered light energy fraction of up to 6%. These results are of crucial importance for the precise assessment of the LPIs in the DCI as well as other laser directly driven ICF schemes.
Exact solutions to macroscopic fluctuation theory through classical integrable systems
Authors: Mallick Kirone , Moriya Hiroki , Sasamoto Tomohiro
Published: July 2024

We give a short overview of recent developments in exact solutions for macroscopic fluctuation theory by using connections to classical integrable systems. A calculation of the cumulant generating function for a tagged particle is also given, agreeing with a previous result obtained from a microscopic analysis.
Integrated modeling of crowd groups based on spatial distribution of members
Authors: Yu Bin , Ou Dongxiu , Ye Jianhong
Published: July 2024

An integrated framework supporting both leader-follower and leaderless groups is proposed. The concept of subgroup is supported so that chains of groups can exist. This allows to model complicated group relationships in crowd simulations. To model group related dynamics, rules are proposed. A detailed explanation of implementation of these rules is given. To validate the proposed framework, two sets of numerical experiments are conducted, using experimental data collected by previous researchers. In one set of experiments, small leader-follower groups without subgroups are considered. In the other set, groups are leaderless and can be small or large with zero or more subgroups. The impact of crowd groups on fundamental diagrams is also experimented. The conducted experiments indicate that the proposed framework can reproduce results that are quite comparable to practical values, thus the framework’s efficacy is validated within a certain range.
Design of high protection liquid cooled BMS system for high voltage energy storage system
Authors: Chen Man , Shen Lingbin , Peng Peng , Wan Minhui , Li Shanpeng , Wang Wenjie , Tan Qipeng , Li Yongqi
Published: July 2024

Aiming at the characteristics of large capacity and high energy density energy storage equipment on the market, a liquid cooled battery management system suitable for high voltage energy storage systems was designed. The overall protection level of the system is IP65. The cooling method adopts liquid cooling heat dissipation, which is common with the overall energy storage system. Compared with traditional air cooling heat dissipation, it has the advantages of high cooling efficiency, low noise and fast cooling speed.
Transient voltage performance and protection design of variable frequency ac three-stage generator for more electric aircraft
Authors: Cheng Fangshun , Chu Wenting , Li Shangsong
Published: July 2024

Nowadays, variable frequency AC generation system is widely used on more electric aircraft because of their advantages of simple structure, high power density, and high reliability. However, a variable frequency system has a wide range of operating speeds and frequencies, and its exciter field is designed to be highly saturated at low speed. Under the condition of a saturated exciter field at high speed, the generator can produce a very high voltage, which will cause damage to aircraft utilization equipment, leading to catastrophic failures. Therefore, to protect the safety of the aircraft, transient voltage regulation performance and voltage protection design are critical in the system design of variable frequency AC generation. This paper focuses on the design of voltage regulation and protection of variable frequency electrical power systems that can meet airworthiness requirements.
Study on laser welding technology of ultra-deep drawing steel DC06 for automobile
Authors: Li Qin , Lai Chun-Ming , Huang Yan
Published: July 2024

The forming, microstructure, and mechanical properties of laser-welded joints of DC06 steel sheets with 0.7 mm thickness were studied. The results show that the microstructure of the weld is ferrite and a little pearlite under different welding conditions. The weld surface formation is better with the increase in welding speed and laser output frequency. With the increase in welding speed, the ferrite grain size of the weld decreases, and the elongation and work hardening index increase.
Structural Design and Driving Experiment of an Electromagnetic Drive System for Microrobot
Authors: Zhang Zhaopeng , Li Hao
Published: July 2024

Controlling the exact positioning and direction of microrobots is a significant challenge in the prospect of microrobot actuation. To solve this problem, the current study created a system that combines solenoid and permanent magnets as an electromagnetic drive mechanism. This system uses a stepping motor to effectively manage the placement of the permanent magnet in the terminal area of solenoid, enabling precise control of its movement. Additionally, a programmable power source is used to adjust the microrobot’s orientation. Driving tests were conducted on a simulated hepatic vein, achieving speeds of up to 1.3mm/s. These results provide valuable references for optimizing future electromagnetic actuation systems.
Research and Implementation of Robotic Arm Positioning and Grasping Based on Visual Guidance
Authors: Liu Qiang , Wang Xinwei , Liu Fengli , Mu Li
Published: July 2024

This paper proposes a robotic arm vision guidance system based on the ROS platform, which combines the Hikrobot Robotics 2D vision sensor with the Xinsong GCR5 robotic arm to successfully realise vision-guided robotic arm positioning and grasping. Camera calibration, hand-eye calibration, and deep learning techniques are used to establish an accurate transformation relationship between the base coordinate system of the robotic arm and the camera coordinate system to achieve efficient target goal recognition and localisation. Adopting the MoveIt framework and RRT-connect algorithm, the robotic arm can flexibly plan the movement path and successfully complete the target grasping, which provides the theoretical basis and practical experience for robotic arm intelligent grasping.
Effects of Ultrafine and Homogenization Process on Microstructure and Properties of H13 Die Steel
Authors: Fan Zhenyu , Wang Huizhen , Zhai Yuewen , Jiang Chao , Guo Shuo , Zhang Zibo , Zhou Leyu
Published: July 2024

The mixed grain structure was found in H13 die steel due to improper production process parameters, and mixed grain structure has adverse effects on the performance of H13 die steel. The appearance of mixed grain structure is analysed. The heredity of mixed grain structure in H13 die steel was eliminated by using ultrafine and homogenization processes. The characteristics of the microstructure of H13 die steel were investigated, and mechanical properties were tested. The results indicated that the mixed grain structure transformed into fine equiaxed grains after the ultrafine and homogenization process and the average grain size of austenite is about 20.7 μm. After quenching and tempering treatment, the hardness of the sample reached 47.1 HRC, and the impact absorption energy was 10.8 J.
A High-pressure Relief Valve Life Measuring System Based on LabVIEW
Authors: Rui Jing , Lidong Zhang
Published: July 2024

High-pressure relief valves have been widely used in machinery, chemical industries, shipbuilding, and other industries, and their service life is a very important performance index. This paper presents a service life measurement system of marine high-pressure relief valves. The system mainly uses a virtual instrument to carry out remote automatic start/stop control and valve position report for the start/stop of the relief valve, confirm the start/stop status, and count the start/stop times within the specified time to reflect the service life of the relief valve.
Reliability Analysis of Hinged Hydraulic System of Remanufactured EPB Shield Machine
Authors: Li Zhibo , Li Yunpeng , Zhao Jingyi , Li Hailong , Wang Bolan
Published: July 2024

To verify the reliability of the Earth Pressure Balance (EPB shield machine) hinged system, firstly, this paper analyses the reliability of the remanufactured EPB shield machine hinged system and then aims at the problem of the high failure rate of the hinged system in EPB shield machine. A fault tree model was established, and the qualitative and quantitative analysis of the fault tree was carried out. Finally, it is determined that the main cause of the oil cylinder malfunction in the hinged system is the insufficient pressure caused by the malfunction of the solenoid valve’s directional switching.