Three-dimensional Mode Research Articles

InGaN surface morphology evolution investigated by atomic force microscope with power spectral density analysis

The morphology of thin InGaN layers grown at varying temperature by metalorganic chemical vapor deposition (MOCVD) has been studied by atomic force microscope (AFM). The surface morphology undergoes a transition process from three-dimensional (3D) island growth mode to two-dimensional (2D) nucleated mound and hillock growth mode and finally to layer-by-layer step-meandering and step flow growth mode. The changes in morphology were analyzed from a thermodynamic (mostly based on the BCF theory of crystal growth by Burton, Cabrera and Frank) and kinetic (mostly the ESB theory based on the Ehrlich-Schwöbel barrier) perspective. Power spectral density (PSD) analysis of AFM surface images is used to determine the dominant smoothing mechanisms that contribute to the feature of surface morphology of InGaN, and validate our analysis based on BCF and ESB theories.

Experimental Study on Uniaxial Compression Mechanics and Failure Characteristics of Non-Through Fractured Rock

The stability of damaged rock mass is a critical problem in the control of surrounding rock in underground engineering. As the main macroscopic defect of rock surrounding engineering, it is of great significance to study its propagation mechanism and the experimental characteristics of rock mechanics. Surface-fractured rock mass is a typical representative of three-dimensional fracture. To reveal the failure mechanism of surface-fractured rock mass, a three-dimensional mechanical failure model of a surface-fractured rock specimen was established, including the initiation, crack propagation, and cooperative deformation of the rock micro-element. Taking the depth of the surface horizontal fissure as a variable, standard rock specimens with surface horizontal fissures of different depths were prepared, and an experimental study of surface-fractured rock specimens was carried out. The RMT rock mechanics test system was used to perform uniaxial compression tests on standard specimens containing fractured rock specimens of different depths. The complete stress–strain curves of samples with different fracture depths were obtained, and the influence of different fracture depths on rock strength and deformation characteristics was analyzed. The crack initiation, propagation, and failure modes of the specimens under uniaxial compression were analyzed based on high-speed camera technology. Through the combination of 3D image processing and acoustic emission monitoring, differences between failure before and after the peak in both asymmetrically damaged rock specimens and symmetrically damaged rock specimens were found. The mechanism of weak strength and weak stability of asymmetrically damaged rock specimens after the peak was explained theoretically. The research results showed that the existence of the horizontal joint plane directly led to a significant reduction in the strength of the jointed rock sample, and the fracture depth played an important role in controlling the failure mode of the jointed rock specimens. The uniaxial compression of rock specimens with horizontal non-penetrating surface fissures produced three-dimensional failure modes, and the depth of surface fissures changed the failure mode of the specimens under uniaxial compression. As the crack depth increased, the failure mode of the specimen changed from tensile failure to shear failure. The surface crack sample showed regional asymmetric failure and poor structural stability.

Improving the accuracy of the PET/MRI tridimensional multimodal rigid image registration based on the FATEMD

The subject matter of the article is the improvement in the accuracy of multimodal image registration between PET and MRI images in the medical field. The focus of the article pertains to the importance of these images in diagnosis, interpretation, and surgical intervention. This study increased the accuracy of PET/MRI multimodal image registration achieved through a new approach based on the multi-resolution image decomposition. The tasks to be solved are: The study proposes a new method, the fast and adaptive three-dimensional mode decomposition (FATEMD), to generate multi-resolution components for accurate registration. The method used: The study uses the FATEMD approach, which estimates the transformation parameters of the registration from the PET image and the residue of the second level of the MRI image that is obtained after the extraction of the first two tridimensional intrinsic mode functions (TIMFs). The following results were obtained: The proposed method of multimodal registration between PET and MRI images involves the use of the fast and adaptive three-dimensional mode decomposition (FATEMD) approach. This approach was tested on 25 pairs of images from the Vanderbilt database and was found to have improved accuracy compared to the usual method, as shown through comparative studies using measures of mutual information, normalized mutual information, and entropy correlation coefficient. Conclusion. The main objective achieved in the study was to enhance the accuracy of PET/MRI multimodal image registration through the application of the FATEMD decomposition method. This approach is novel compared to traditional methods as it involves estimating the transformation parameters from the PET image and the second level residue of the MRI image, resulting in more precise outcomes as opposed to using just the PET and MRI images alone. The integration of multiple imaging techniques, such as PET and MRI, provides healthcare professionals with a more comprehensive view of a patient's anatomy and physiology, leading to enhanced diagnosis and treatment planning.

On the origin of spanwise vortex deformations during the secondary instability stage in compressible mixing layers

The three-dimensionality of turbulence initiates with spanwise vortex deformations associated with the amplification of three-dimensional disturbance modes. However, the origin of spanwise vortex deformations is still not well understood. In this paper, compressible mixing layers are performed via direct numerical simulation (DNS). Two typical types of secondary instabilities producing spanwise vortex deformations are of consideration: fundamental instability and subharmonic instability. Based on the fast Fourier transform and DNS data, a low-rank velocity model v0 is obtained to demonstrate that spanwise vortex deformations are originated from a linear superposition of fundamental norm mode, a pair of fundamental or subharmonic oblique modes, and the mean mode. Through observing flow structures of the above norm and oblique modes, a striking feature is found that the velocity model v0 containing deformed spanwise vortices can be decomposed into three new velocity models v1, v2, and v3 containing relatively simplified counterparts (spanwise or oblique vortices). Then, the instability mechanism of the latter vortices is explored by analyzing the position relationship between the function of the generalized inflection points and cores of relatively simplified vortices. We find that an inviscid inflectional instability mechanism is responsible for the formation of spanwise and oblique vortices. Based on the above findings, a view is first proposed that spanwise vortex deformations with aligned and staggered patterns are a joint result of the parametric resonant mechanism and the inviscid inflectional instability mechanism.

Development of multiphysics coupling system for nuclear fuel rod with COMSOL and RMC

Coupling fuel performance and neutronics can help improve the prediction accuracy of fuel rod behavior, which is important for fuel design and performance evaluation. A fuel rod multiphysics coupled system was developed with multiphysics software COMSOL and 3D Monte Carlo neutron transport code RMC. The fuel performance analysis module was built on top of COMSOL with the ability to simulate the fuel behavior in two-dimensional axisymmetric (2D-RZ) or three-dimensional (3D) mode. RMC was innovatively wrapped as a component of COMSOL to communicate with the fuel performance analysis module. The data transferring and the coupling process was maintained using COMSOL’s functionality. Two-way coupling was achieved by mapping power distribution and fast neutron flux fields from RMC to COMSOL and the temperature and coolant density fields from COMSOL to RMC. A fuel rod pin lattice was modeled to demonstrate the coupling. Results show that the calculated power and temperature distributions are reasonable. Considering the flexibility of the coupled system, it can be applied to the performance evaluation of new fuel design.

Three-dimensional on-chip mode converter.

The implementation of transverse mode, polarization, frequency, and other degrees of freedom (d.o.f.s) of photons is an important way to improve the capability of photonic circuits. Here, a three-dimensional (3D) linear polarized (LP) LP11 mode converter was designed and fabricated using a femtosecond laser direct writing (FsLDW) technique. The converter included multi-mode waveguides, symmetric Y splitters, and phase delaying waveguides, which were constructed as different numbers and arrangements of circular cross section waveguides. Finally, the modes (LP11a and LP11b) were generated on-chip with a relatively low insertion loss (IL). The mode converter lays a foundation for on-chip high-order mode generation and conversion between different modes, and will play a significant role in mode coding and decoding of 3D photonic circuits.

Construction of a 5G-based, three-dimensional, and efficiently connected emergency medical management system

BackgroundShenzhen is unique in its need for ad hoc responses to emergencies. The need for emergency medicine also demonstrates a trend of sustained growth. ObjectiveA three-dimensional and efficiently connected emergency medical management model using fifth generation mobile communication technology (5G) was established to improve the efficiency and level of management in emergency medicine. MethodA mixed-frequency band private network collaborative emergency treatment mode was built under daily emergency scenarios using 5G. The efficiency of a three-dimensional telemedicine treatment mode was tested using prehospital emergency medicine. Also, the feasibility of quickly establishing a temporary network information system using unmanned aerial vehicle (UAV) and/or high-throughput communication satellites under disaster-caused power outages and network interruptions was examined. A monitoring system was constructed for suspected cases using 5G amid public health emergencies, which raised the Emergency Department’s efficiency and security in responding to the pandemic. ResultsThe three-dimensional rescue system supported by 5G showed that the radius of the emergency medical rescue services expanded from 5 to 60 km, and the cross-district emergency reaction time reduced from 1 h to <20 min. Thus, it was feasible to construct a communication network expeditiously with devices carried by UAV under disastrous scenarios. The system developed based on 5G could be used in managing suspected cases of public emergencies. Among the 134 suspected cases in the early stage of the pandemic, no nosocomial infection was detected. ConclusionA three-dimensional, efficiently connected emergency medical management system based on 5G was constructed, following which the emergency rescue radius quickly expanded and the emergency response time reduced. Thus, with the aid of new technology, an emergency information network system was built expeditiously under specific scenarios, such as a natural disaster, and the level of management under public health emergencies advances. The confidentiality of patient information is a critical issue regarding the application of new technology.

Scaling analysis parameters in 3D-focusing velocity map imaging

Velocity map imaging spectrometer is a powerful tool for measuring the two-dimensional momenta of charged particles in dissociative photoionization processes. By combining a time-position sensitive detector with a three-dimensional (3D) source focusing mode, 3D momentum can be measured at a much higher resolution. However, due to the side effects of the non-uniform electric field in this mode, the retrieval of the 3D momentum becomes complicated. Here, we describe a method to retrieve the 3D momentum from the time of flight and the position at a numerical accuracy better than 0.1%, much below the best achievable relative energy resolution of 1% in the reported experiments. The method is consistently tested on simulated data, including ions with different masses and charges. Moreover, a scaling relationship is established among them.

Three-dimensional mode multiplexer based on adiabatic-tapered waveguides forming vertical directional couplers over C + L band and beyond.

We present a mode multiplexer based on vertical directional couplers that are formed by adiabatic-tapered waveguides. We design and fabricate the device via the micro-fabrication processing to (de)multiplex the E11, E21, and E12 modes from the few-mode bus waveguide. Our experimental device shows a coupling ratio higher than 98.6% and 97.0% for the E21 and E12 modes, respectively, over the C + L band and beyond. The modal cross talk of this device can be lower than -17.1 dB, -18.4 dB, and -15.1 dB caused by the unintended E11, E21, and E12 modes, respectively. This mode multiplexer can work over a broader wavelength range with weak polarization sensitivity, which could be used in the mode-division-multiplexing systems where mode (de)multiplexing is required in the expanded communication wavelength window other than the C-band.

Global stability, sensitivity and passive control of low-Reynolds-number flows around NACA 4412 swept wings

The stability and sensitivity of two- and three-dimensional global modes developing on steady spanwise-homogeneous laminar separated flows around NACA 4412 swept wings are numerically investigated for different Reynolds numbers ${\textit {Re}}$ and angles of attack $\alpha$ . The wake dynamics is driven by the two-dimensional von Kármán mode whose emergence threshold in the $\alpha \unicode{x2013}{\textit {Re}}$ plane is computed with that of the three-dimensional centrifugal mode. At the critical Reynolds number, the Strouhal number, the streamwise wavenumber of the von Kármán mode and the spanwise wavenumber of the leading three-dimensional centrifugal mode scale as a power law of $\alpha$ . The introduction of a sweep angle attenuates the growth of all unstable modes and entails a Doppler effect in the leading modes’ dynamics and a shift towards non-zero frequencies of the three-dimensional centrifugal modes. These are found to be non-dispersive as opposed to the von Kármán modes. The sensitivity of the leading global modes is investigated in the vicinity of the critical conditions through adjoint-based methods. The growth-rate sensitivity map displays a region on the suction side of the wing, wherein a streamwise-oriented force has a net stabilising effect, comparable to what could have been obtained inside the recirculation bubble. In agreement with the predictions of the sensitivity analysis, a spanwise-homogeneous force suppresses the Hopf bifurcation and stabilises the entire branch of von Kármán modes. In the limit of small amplitudes, passive control via spanwise-wavy forcing produces a stabilising effect similar to that of a spanwise-homogeneous control and is more effective than localised spherical forces.

Experimental study on the thermal characteristics of a 3D thermosyphon heat sink

Phase change heat transfer has received extensive attention in the thermal management of electronic devices. Most studies of heat pipe or vapor chamber were limited to one- or two-dimensional heat transfer mode. Enhancing the phase change heat transfer to three-dimensional mode in heat sinks and exploring the thermal behavior of the heat sinks deserve a dedicated study. In this paper, a three-dimensional thermosyphon (3D-TS) heat sink combining the superiorities of the vapor chamber, thermosyphon and folded fins was experimentally investigated. The experimental reliability was validated and consolidated by the heat loss analysis, and an iteration method was proposed to estimate the saturation temperature to facilitate the in-depth analysis of the results. The coupling characteristics of the air forced convection and phase change heat transfer, and the effects of the heating power and air volume flow rate on the thermal resistance of 3D-TS were involved in the discussion. The main results indicate that the overall thermal resistance exhibits a negative correlation with the heating power and the air volume flow rate. The lowest thermal resistance of 0.14 K·W−1 was achieved with Qtotal = 300 W and 100 CFM air volume flow rate. High temperature on the folded fins indicates that the phase change heat transfer extends from the flat vapor chamber to the vertical thermosyphon tubes. It is also found that for a small heating power, a relatively large air volume flow rate is not able to further reduce the overall thermal resistance due to inadequate phase change intensity. The proposed heat sink is expected to solve the heat dissipation problems for densely packed electronic devices, which can produce favorable performance according to the input heating power and appropriate air volume flow rate.

Triglobal resolvent analysis of swept-wing wakes

Through triglobal resolvent analysis, we reveal the effects of wing tip and sweep angle on laminar separated wakes over swept wings. For the present study, we consider wings with semi-aspect ratios from $1$ to $4$ , sweep angles from $0^\circ$ to $45^\circ$ and angles of attack of $20^\circ$ and $30^\circ$ at a chord-based Reynolds number of $400$ and a Mach number of $0.1$ . Using direct numerical simulations, we observe that unswept wings develop vortex shedding near the wing root with a quasi-steady tip vortex. For swept wings, vortex shedding is seen near the wing tip for low sweep angles, while the wakes are steady for wings with high sweep angles. To gain further insights into the mechanisms of flow unsteadiness, triglobal resolvent analysis is used to identify the optimal spatial input–output mode pairs and the associated gains over a range of frequencies. The three-dimensional forcing and response modes reveal that harmonic fluctuations are directed towards the root for unswept wings and towards the wing tip for swept wings. The overlapping region of the forcing–response mode pairs uncovers triglobal resolvent wavemakers associated with self-sustained unsteady wakes of swept wings. Furthermore, we show that for low-aspect-ratio wings optimal perturbations develop globally over the entire wingspan. The present study uncovers physical insights on the effects of tip and sweep on the growth of optimal harmonic perturbations and the wake dynamics of separated flows over swept wings.

Displacement response characteristics of different sand tunnel excavation faces under true triaxial loading

During the construction of subway tunnels, the geotechnical body is affected by excavation to produce three-dimensional spatial deformation. The deformation of geotechnical bodies is an important safety hazard for project advancement, so it is important to understand the excavation disturbance range and deformation mechanism. The current related research is mainly about the theory of land subsidence and the two-dimensional plane displacement of the stratum, and there are few studies on the specific three-dimensional disturbance mode and its mechanism. In order to better understand the three-dimensional displacement characteristics of the tunnel excavation soil, a tunnel excavation model test was established based on a true triaxial stress loading system combined with three-dimensional scanning technology for a superimposed sandy soil. Based on the established model, the vector displacement response range and three-dimensional deformation characteristics of the excavation face were studied in the main displacement affected area around the excavation face. Meanwhile, the deformation characteristics, such as vertical settlement and horizontal displacement of the stratum in the main influence area were analyzed. The results show that the main influence area of tunnel excavation is elliptical and distributed within a range of twice the diameter of the tunnel axis. The main influence range is bell-shaped in the vertical direction and inverted wedge-shaped in the horizontal direction. The three-dimensional space presents a “W” deformation distribution. The three-dimensional deformation theoretical model of the excavation face established in this paper can provide some references for the excavation engineering of superimposed sand-soil tunnels.

Three-dimensional Teaching Mode of the Course "On Camera Journalists and Live Reports" under the Background of Media Integration

Three-dimensional Teaching Mode of the Course "On Camera Journalists and Live Reports" under the Background of Media Integration

Comparative studies on the thin films of dicyanoanthracene grown on metal and semimetal surfaces

The interactions between molecules and substrates play an important role in growing organic thin films. The metallic and semimetallic substrates, owing to the different electronic structures, can have distinct interactions with molecular films. Here we make a comparative study on the two-dimensional (2D) self-assemblies of dicyanoanthracene (DCA) molecules on the metallic Cd(0001) and semimetallic Bi(111) surfaces. It is found that the DCA thin film grown on Cd(0001) surface at low temperature exhibits a three-dimensional (3D) growth mode, with the monolayer islands, two-layer islands, and three-layer islands coexisting on the Cd(0001) surface. When deposited at room temperature, the DCA molecules exhibit a 2D growth mode, where the monolayer DCA adopts the 4×&lt;inline-formula&gt;&lt;tex-math id="Z-20230308215342"&gt;\begin{document}$\sqrt {13} $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20222197_Z-20230308215342.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20222197_Z-20230308215342.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; reconstruction with respective Cd(0001). The commensurate epitaxy indicates that there is strong interaction between DCA molecules and Cd(0001). In clear contrast, the DCA molecules deposited on the semimetallic Bi(111) surface at low temperature exhibit a 2D growth mode. Furthermore, a moiré pattern with the periodicity of 2.6 nm is observed in the DCA monolayer, indicating the incommensurate epitaxy of DCA monolayer on Bi(111). This can be explained by the weak interaction between DCA and Bi(111) substrate. These results demonstrate that both of the electronic structure of substrates and substrate temperatures can be used to adjust the structures of morphology of DCA films.

The Design and Exploration of Ideological and Political Teaching in College English under the Mixed Teaching Model

Adhering to the combination of knowledge teaching and value guidance, the teaching practice of ideological and political education in college English not only guides young students to critically study western culture, spread Chinese culture, and tell Chinese stories, but also enhances college students' love and confidence in national culture. Through the combination of online and offline teaching, the mixed teaching mode integrates the ideological and political education mode of the curriculum with the teaching of professional courses, and presents a three-dimensional teaching mode in the design of teaching activities, the interpretation of teaching content, the guidance of teaching methods, the practice of teaching links and the evaluation of teaching effects, so as to achieve the effectiveness of ideological and political education of the curriculum.

Three-dimensional multi-component analysis of Aurantii Fructus quality and research on influencing factors

The present study explored the consistency of the content proportions of active components of Aurantii Fructus and analyzed the influencing factors based on three-dimensional multi-component analysis. A total of 839 Aurantii Fructus samples in 65 research articles were analyzed using the three-dimensional multi-component analysis mode. The content data of flavonoid components(naringin, hesperidin, neohesperidin, narirutin, and nobiletin), coumarin components(meranzin and gluconolactone), and alkaloid(synephrine) in 386 samples which met the criteria of 2020 edition of the Chinese Pharmacopoeia were extracted and adjusted to percentages, and the content ratios between components were calculated. The influencing factors of Aurantii Fructus quality were analyzed. The results showed content ratios of components as follows: neohesperidin∶naringin in the range of 0.4-1.2; narirutin∶naringin in the range of 0.02-0.16; hesperidin∶naringin in the range of 0.01-0.3; nobiletin∶naringin in the range of 0.000 588 3-0.069 68; synephrine∶naringin in the range of 0.02-0.042; gluconolactone∶naringin in the range of 0.001-0.01; meranzin∶naringin in the range of 0.000 4-0.035. The quality of Aurantii Fructus was closely related to the origin, variety, harvesting time, and processing method of medicinal materials. Harvesting time had a greater impact on the quality of Aurantii Fructus, and the origin and variety had a certain impact on the quality of Aurantii Fructus. The findings of this study indicated that the ratios between flavonoid components, flavonoids and coumarin components, and flavonoids and alkaloids fluctuated. The production base should optimize the varieties, harvesting period, and processing methods of Aurantii Fructus to provide a scientific basis for the production of high-quality Aurantii Fructus.

Research and Practice of Mental Health Education for College Students in Local Colleges Research on Innovation of Teaching Model

Under the application-oriented talent training mode, theoretical and practical exploration is one of the effective parts of college students’ mental health education course. The three-dimensional practical teaching mode built by psychological evaluation, group psychological counseling and behavioral training in the course of “College Students’ Mental Health Education” is very obvious to the overall effect of the course teaching. This paper puts forward innovative strategies for practical teaching research and training of mental health education in local colleges and universities: strengthen the sense of identity of mental health teaching, combine reality with theory, extend after-class extension within class, so as to improve the teaching effect.

3-D tissue-engineered epidermis against human primary keratinocytes apoptosis via relieving mitochondrial oxidative stress in wound healing

The tissue-engineered epidermal (TEE), composed of biocompatible vectors and autogenous functional cells, is a novel strategy to solve the problem of shortage of donor skin sources. The human primary keratinocyte (HPK), the major skin components, are self-evident vital in wound healing and was considered as one of the preferred seed cells for TEEs. Since the process of separating HPKs from the skin triggers a stress state of the cells, achieving its rapid adhesion and proliferation on biomaterials remains challenging. The key to the clinical application is to ensure the normal function of cells while improving the proliferation ability in vitro, and to complete the complex mesenchymal epithelialization to achieve tissue remodeling after vivo implantation. Herein, in order to aid HPKs adhesion and proliferation in vitro and promoting wound healing, we developed a three dimensional collagen scaffold with Y-27632 sustainedly released from the nanoplatform, hollow mesoporous organosilica nanoparticles (HMON). The results showed that the porous structure within the TEE supports the implanted HPKs expanding in a three-dimensional mode to jointly construct the tissue-engineered epidermis in vitro and inhibited the mitochondria-mediated cell apoptosis. It was confirmed that the TEEs with suitable degradation rate could maintain drug release after implantation and could accelerate vascularization of wound base and further revealed the involvement of mesenchymal transformation of transplanted HPKs during skin regeneration in a nude mouse model with full-thickness skin resection. In conclusion, our study highlights the great potential of constructing TEE using a nanoparticle platform for the treatment of large-area skin defects.

Study of Copper Electrodeposition at a Very Low Temperature near the Freezing Point of Electrolyte

At or above room temperature, metal electrodeposits often feature coarse grains, uneven microstructure and high roughness with abnormal bulges. In this study, copper electrodeposits with abnormal properties were prepared in a sulfate bath at a low temperature near the freezing point of the electrolyte. The results showed that the average grain size of the copper featured an "increase-decrease" trend while decreasing the temperature form 5 °C to -5 °C, yielding a trend from 0.25 μm to 1 μm and then to 0.6 μm. In the early stage, the temperature does not change the three-dimensional continuous nucleation mode of deposited copper. When the nucleus density reaches saturation, the polarization caused by overpotential will act on the respective nucleation and crystal growth process twice, and finally exhibit a completely different trend than that at room temperature. This study may provide insights for breakthroughs in material properties from a temperature perspective.