BACKGROUND Fracture is one of the most pervasive injuries in the musculoskeletal system,and there is a complex interaction between macrophages and adipose tissue-derived stem cells(ADSCs)in fracture healing.However,tw...BACKGROUND Fracture is one of the most pervasive injuries in the musculoskeletal system,and there is a complex interaction between macrophages and adipose tissue-derived stem cells(ADSCs)in fracture healing.However,two-dimensional(2D)coculture of macrophages and ADSCs can not accurately mimic the in vivo cell microenvironment.AIM To establish both 2D and 3D osteogenic coculture models to investigate the interaction between macrophages and ADSCs.METHODS After obtaining ADSCs from surgery and inducing differentiation of the THP1 cell line,we established 2D and 3D osteogenic coculture models.To assess the level of osteogenic differentiation,we used alizarin red staining and measured the relative expression levels of osteogenic differentiation markers osteocalcin,Runt-related transcription factor 2,and alkaline phosphatase through polymerase chain reaction.Verification was conducted by analyzing the expression changes of N-cadherin and the activation of the Wnt/β-catenin signaling pathway using western blotting.RESULTS In this study,it was discovered that macrophages in 3D culture inhibited osteogenic differentiation of ADSCs,contrary to the effect in 2D culture.This observation confirmed the significance of intricate intercellular connections in the 3D culture environment.Additionally,the 3D culture group exhibited significantly higher N-cadherin expression and showed reducedβ-catenin and Wnt1 protein levels compared to the 2D culture group.CONCLUSION Macrophages promoted ADSC osteogenic differentiation in 2D culture conditions but inhibited it in 3D culture.The 3D culture environment might inhibit the Wnt/β-catenin signaling pathway by upregulating N-cadherin expression,ultimately hindering the osteogenic differentiation of ADSCs.By investigating the process of osteogenesis in ADSCs,this study provides novel ideas for exploring 3D osteogenesis in ADSCs,fracture repair,and other bone trauma repair.展开更多
As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and el...As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and electrochemical characteristics,MXenes have shown great potential in brain-inspired neuromorphic computing electronics,including neuromorphic gas sensors,pressure sensors and photodetectors.This paper provides a forward-looking review of the research progress regarding MXenes in the neuromorphic sensing domain and discussed the critical challenges that need to be resolved.Key bottlenecks such as insufficient long-term stability under environmental exposure,high costs,scalability limitations in large-scale production,and mechanical mismatch in wearable integration hinder their practical deployment.Furthermore,unresolved issues like interfacial compatibility in heterostructures and energy inefficiency in neu-romorphic signal conversion demand urgent attention.The review offers insights into future research directions enhance the fundamental understanding of MXene properties and promote further integration into neuromorphic computing applications through the convergence with various emerging technologies.展开更多
Superconductivity in two-dimensional(2D)materials has attracted considerable attention due to their unique physical properties and potential for high-temperature operation.Boron-based 2D compounds are particularly pro...Superconductivity in two-dimensional(2D)materials has attracted considerable attention due to their unique physical properties and potential for high-temperature operation.Boron-based 2D compounds are particularly promising,thanks to their structural flexibility and the emergence of strong electron-phonon coupling(EPC)associated with light elements.While most previous studies have focused on stabilizing boron sheets through metal incorporation,we propose an alternative approach based on multicenter bonding enabled by group-IV non-metallic elements(Si,Ge,Sn).The resulting XB_(2)(X=Si,Ge,Sn)monolayers,which adopt a MgB_(2)-like monolayer configuration,are stabilized by a seven-center two-electron(7c-2e)bonding network between the X atoms and the boron honeycomb lattice.This bonding lowers the energy of the B-p_(z)orbitals and enhances lattice stability.The superconducting transition temperature(T_(c))increases significantly with the atomic number of X—from 4.7 K in SiB_(2)to 13.3 K in GeB_(2)and 24.9 K in SnB_(2)—driven by an increased carrier density near the Fermi level(E_(F))and softening of the high-frequency E_(2)phonon mode.Furthermore,we design a SnB_4 monolayer,in which a Sn layer is sandwiched between the two boron layers.This structure enriches in-plane phonon modes and strengthens EPC,yielding a T_(c)of 38 K,close to the McMillan limit.These findings highlight the critical role of multicenter bonding and targeted phonon engineering in enabling high-T_(c)2D boron-based superconductors.展开更多
Two-dimensional(2D)multilayer kagome materials hold significant research value for regulating kagome-related physical properties and exploring quantum effects.However,their development is hindered by the scarcity of a...Two-dimensional(2D)multilayer kagome materials hold significant research value for regulating kagome-related physical properties and exploring quantum effects.However,their development is hindered by the scarcity of available material systems,making the identification of novel 2D multilayer kagome candidates particularly important.In this work,three types of 2D materials with trilayer kagome lattices,namely Sc_(6)S_(5)X_(6)(X=Cl,Br,I),are predicted based on first-principles calculations.These 2D materials feature two kagome lattices composed of Sc atoms and one kagome lattice composed of S atoms.Stability analysis indicates that these materials can exist as free-standing 2D materials.Electronic structure calculations reveal that Sc_(6)S_(5)X_(6)are narrow-bandgap semiconductors(0.76–0.95 e V),with their band structures exhibiting flat bands contributed by Sc-based kagome lattices and Dirac band gaps resulting from symmetry breaking.The sulfur-based kagome lattice in the central layer contributes an independent flat band below the Fermi level.Additionally,Sc_(6)S_(5)X_(6)exhibit high carrier mobility,with hole and electron mobilities reaching up to 10^(3)cm^(2)·V^(-1)·s^(-1),indicating potential applications in low-dimensional electronic devices.This work provides an excellent example for the development of novel multilayer 2D kagome materials.展开更多
According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing ...According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.展开更多
AIM： To investigate the value of two-dimensional （2D） and three-dimensional （3D） double contrast-enhanced ultrasonography （DCUS） imaging for evaluation of gas- tric lesions. METHODS： 2D and 3D DCUS imaging wit...AIM： To investigate the value of two-dimensional （2D） and three-dimensional （3D） double contrast-enhanced ultrasonography （DCUS） imaging for evaluation of gas- tric lesions. METHODS： 2D and 3D DCUS imaging with both oral and intravenous administrations of contrast agents was used to assess gastroscopiclly-confirmed gastric lesions in 46 patients with benign and malignant diseases. Initially, liquid-based ultrasound contrast agent （Xinzhang） was given orally at dose of 500-600 mL for conventional ultrasound examination of the gastric lesions, and then a microbubble-based contrast agent （SonoVue） was injected intravenously at dose of 1.2-2.4 mL in bolus fashion to assess the perfusion pattern of the lesions using contrast imaging modes. The parameters derived from time-intensity curves including the arrival time （AT）, time to peak （lq-P）, peak intensity （PI） and en- hanced intensity （EI） were measured on the 2D DCUS imaging. 3D DCUS of the lesions was acquired to dem- onstrate the value of this imaging mode. RESULTS： There were 22 cases with benign lesions including chronic gastritis （n= 5）, gastric ulcer （n = 9）, gastric polyps （n = 3）, gastric stromal tumors （n = 5）, and 24 cases with malignant lesions including gastric cancer （n = 20）, gastric cardia carcinoma （n = 3） and post-operative recurrent gastric cancer （n = 1） in the study, The oral contrast-enhanced ultrasonography （CEUS） imaging of the stomach clearly demonstrated the anatomy of the stomach and morphologic features of gastric lesions, With optimal scanning window and imaging display under oral CEUS, intravenous CEUS clearly showed the perfusion of gastric lesions with various characteristic manifestations. Both 2D and 3D DCUS images clearly demonstrated normal gastric wall as a three-layer structure, from the inside out, hypere- choic mucosa, hypoechoic muscularis and hyperechoic serosa, respectively. There were statistical significant differences of AT （8.68±2.06 vs 10.43 ±2.75, P = 0.017）, PI （34.64 ± 6.63 vs 29.58 ± 8.22, P = 0.023） and EI （29.72 ± 6.69 vs 22.66 ± 7.01, P = 0.001） between malignant lesions and normal gastric wall. However, no differences of AT, PI and EI between benign lesions and normal gastric wall tissue were found. 3D DCUS could intuitively display morphological features and vascularities of the lesions with multiplanar and volume views. 3D DCUS imaging provided comprehen- sive information complementary to 2D imaging. The crater or wellhead appearances and feeding vessels as well as distorted nourishing vasculature of gastric carcinoma were better seen with 3D imaging than 2D imaging. CONCLUSION： DCUS imaging can simultaneouslydisplay the anatomic and perfusion features of gastric lesions. 3D DCUS can provide additional information to 2D DCUS for evaluation of gastric lesions.展开更多
AIM: To define the benefits of three-dimensional video-assisted thoracoscopic esophagectomy(3D-VATE)over 2D-VATE for esophageal cancer.METHODS: A total of 93 patients with esophageal cancer including 45 patients recei...AIM: To define the benefits of three-dimensional video-assisted thoracoscopic esophagectomy(3D-VATE)over 2D-VATE for esophageal cancer.METHODS: A total of 93 patients with esophageal cancer including 45 patients receiving 3D-VATE and48 receiving 2D-VATE were evaluated. Data related to patient and cancer characteristics, operating time,intraoperative bleeding, morbidity and mortality,postoperative inflammatory markers, Numerical Rating Scale for postoperative pain, Constant-Murley rating system for shoulder recovery and oxygenation index(OI) were collected. All medical records were retrieved from a prospectively maintained oncological database at our institution. A retrospective study was performed to compare the short-term surgical outcomes between the two groups.RESULTS: No significant differences were found between the two groups in either morbidity or mortality(P = 0.328). An enhanced surgical recovery was noted in the 3D group as indicated by shortened thoracoscopic operation time(3D vs 2D: 68 ± 13.79 min vs 83 ± 13min, P < 0.01), minor intraoperative blood loss(3D vs 2D: 68.2 ± 10.7 ml vs 89.8 ± 10.4 ml, P < 0.01),earlier chest tube removal(3D vs 2D: 2.67 ± 1.01 vs3.75 ± 1.15 d, P < 0.01), shorter length of hospital stay(3D vs 2D: 9.07 ± 2.00 vs 10.85 ± 3.40 d, P <0.01), lower in-hospital expenses(3D vs 2D: 74968.4± 9637.8 vs 86211.1 ± 8519.7 RMB, P < 0.01), lower pain intensity(P < 0.01) and faster recovery of the left shoulder function(P < 0.01). Better preservation of the pulmonary function was also found in the 3D group as the decline of the OI post operation was significantly lower than that of the 2D group(P < 0.01). Changes of postoperative inflammatory markers, including procalcitonin [postoperative days(PODs) 4 and 7: P <0.01], peripheral granulocytes(PODs 1, 4 and 7: P <0.01) and hypersensitive C-reactive protein(POD 4: P< 0.01) in 3D-VATE patients were less than those in the 2D group. Moreover, utilization of the 3D technique extended the dissection of the thoracic lymph nodes(P < 0.01), with better exposure of nodes in the left recurrent laryngeal nerve(P = 0.031).CONCLUSION: 3D-VATE could be a more viable technique over 2D-VATE in terms of short-term outcomes for patients with esophageal cancer.展开更多
Summary： This study sought to evaluate the contribution of two-dimensional ultrasound （2D-US） and three-dimensional skeletal imaging ultrasound （3D-SUIS） in the prenatal diagnosis of sirenomelia. Be- tween Septem...Summary： This study sought to evaluate the contribution of two-dimensional ultrasound （2D-US） and three-dimensional skeletal imaging ultrasound （3D-SUIS） in the prenatal diagnosis of sirenomelia. Be- tween September 2010 and April 2014, a prospective study was conducted in a single referral center using 3D-SU1S performed after 2D-US in 10 cases of sirenomelia. Diagnostic accuracy and detailed findings were compared with postnatal three-dimensional helical computed tomography （3D-HCT）, radiological findings and autopsy. Pregnancy was terminated in all 10 sirenomelia cases, including 9 singletons and I conjoined twin pregnancy, for a total of 5 males and 5 females. These cases of sirenomelia were deter- mined by autopsy and/or chromosomal examination. Initial 2D-US showed that there were 10 cases of oligohydranmios, bilateral renal agenesis, bladder agenesis, single umbilical artery, fusion of the lower limbs and spinal abnormalities; 8 cases of dipus or monopus; 2 cases of apus; and 8 cases of cardiac abnormalities. Subsequent 3D-SUIS showed that there were 9 cases of scoliosis, l0 cases of sacrococ- cygeal vertebra dysplasia, 3 cases of hemivertebra, 1 case of vertebral fusion, 3 cases of spina bifida, and 5 cases of rib abnormalities. 3D-SUIS identified significantly more skeletal abnormalities than did 2D-US, and its accuracy was 79.5% （70/88） compared with 3D-HCT and radiography. 3D-SUIS seems to be a useful complementary method to 2D-US and may improve the accuracy of identifying prenatal skeletal abnormalities related to sirenomelia.展开更多
Both the design process and form of the three-dimensional （3D） suboptimal guidance law （3DSGL） are very complex. Therefore, we propose the use of two-dimensional （2D） guidance laws to meet the guidance requireme...Both the design process and form of the three-dimensional （3D） suboptimal guidance law （3DSGL） are very complex. Therefore, we propose the use of two-dimensional （2D） guidance laws to meet the guidance requirements of 3D space. By analyzing the relationship between the flight-path angle and its projections on OXY and OXZ planes, we obtain the ideal design requirements of the guidance laws. Based on the requirements, we design a 2D suboptimal guidance law used in the horizontal plane; combining the 2D vertical suboptimal guidance law, we create a whole ballistic simulation of six degree-of-freedom. The results are compared with those using other three guidance modes in the case of large windage of the initial azimuth angle. When the proportional navigation guidance （PNG） law is used in the horizontal planes, the landing angle will obviously decrease. With the proposed guidance mode, the large landing angle can be realized and meet the guidance precision requirements. Moreover, the required overload can decrease to meet the control requirement. The effects of the proposed guidance mode are close to that of 3DSGL despite its very simple form.展开更多
Multiple-point statistics(MPS)is a useful approach to reconstruct three-dimensional models in the macroscopic or microscopic field.Extracting spatial features for three-dimensional reconstruction from two-dimensional ...Multiple-point statistics(MPS)is a useful approach to reconstruct three-dimensional models in the macroscopic or microscopic field.Extracting spatial features for three-dimensional reconstruction from two-dimensional training images(TIs),and characterizing non-stationary features with directional ductility are two key issues in MPS simulation.This study presents a step-wise MPS-based three-dimensional structures reconstruction algorithm with the sequential process and hierarchical strategy based on two-dimensional images.An extension method is proposed to construct three-dimensional TIs.With a sequential simulation process,an initial guess at the coarsest scale is simulated,in which hierarchical strategy is used according to the characteristics of TIs.To obtain a more refined realization,an expectation-maximization like iterative process with global optimization is implemented.A concrete example of chondrite micro-structure simulation,in which one scanning electron microscopy(SEM)image of the Heyetang meteorite is used as TI,shows that the presented algorithm can simulate complex non-stationary structures.展开更多
Three-dimensional(3D)reconstruction of human organs has gained attention in recent years due to advances in the Internet and graphics processing units.In the coming years,most patient care will shift toward this new p...Three-dimensional(3D)reconstruction of human organs has gained attention in recent years due to advances in the Internet and graphics processing units.In the coming years,most patient care will shift toward this new paradigm.However,development of fast and accurate 3D models from medical images or a set of medical scans remains a daunting task due to the number of pre-processing steps involved,most of which are dependent on human expertise.In this review,a survey of pre-processing steps was conducted,and reconstruction techniques for several organs in medical diagnosis were studied.Various methods and principles related to 3D reconstruction were highlighted.The usefulness of 3D reconstruction of organs in medical diagnosis was also highlighted.展开更多
To solve the problem of the lack of comprehensive evaluation of three-dimensional(3D)asphalt pavement roughness,a method for evaluating the asphalt pavement roughness is proposed based on two-dimensional(2D)power spec...To solve the problem of the lack of comprehensive evaluation of three-dimensional(3D)asphalt pavement roughness,a method for evaluating the asphalt pavement roughness is proposed based on two-dimensional(2D)power spectral density(PSD).By calculating the 2D PSD of a 3D asphalt pavement and converting it into the longitudinal average asphalt pavement PSD,the relationship between the evaluation method of the 3D asphalt pavement roughness and the current evaluation standard of roughness is established.Combined with the road-fitting formula used in international standards,the elevation data of the A,B,C,and D grades of the 3D asphalt pavement are simulated by the harmonic superposition method.According to the proposed method,the longitudinal PSD of each level of simulated asphalt pavement is calculated and compared with the standard spectral line of each pavement level.This approach verifies the effectiveness of the proposed method in evaluating the roughness of the 3D asphalt pavement.Compared with the PSD of a certain horizontal profile elevation,it is verified that the fluctuation amplitude of the spectral line calculated by the proposed method is greatly improved.The results show that the proposed method can evaluate the roughness of asphalt pavements more comprehensively and accurately and has strong practicability.展开更多
2D nanosheets such as graphene, silicene, phosphorene, metal dichalcogenides and MXenes are emerging and promising for lithium storage due to their ultrathin nature and corresponding chemical/physical properties. Howe...2D nanosheets such as graphene, silicene, phosphorene, metal dichalcogenides and MXenes are emerging and promising for lithium storage due to their ultrathin nature and corresponding chemical/physical properties. However, the serious restacking and aggregation of the 2D nanosheets are still hampering their applications. To circumvent the issues of 2D nanosheets, one efficient strategy is to construct 3D structures with hierarchical porous structures, good chemical/mechanical stabilities and tunable electrical conductivities. In this review, we firstly focus on the available synthetic approaches of 3D structures from 2D nanosheets, and then summarize the relationships between the microstructures of 3D structures built from 2D nanosheets and their electrochemical behaviors for lithium storage. On the basis of above results, some challenges are briefly discussed in the perspective of the development of various functional 3D structures.展开更多
Background Two-dimensional speckle tracking imaging （2D-STI） and real-time three-dimensional echocardiography （RT-3DE） have more advantages in evaluating left ventricular （LV） systolic dyssynchrony than traditio...Background Two-dimensional speckle tracking imaging （2D-STI） and real-time three-dimensional echocardiography （RT-3DE） have more advantages in evaluating left ventricular （LV） systolic dyssynchrony than traditional echocardiographic techniques. The study aimed to evaluate LV dyssynchrony parameters by both 2D-STI and RT-3DE, and the correlation between these two techniques. Methods A total of 43 chronic heart failure （CHF） patients and 27 healthy volunteers were enrolled. There were 23 dyssynchrony parameters selected to evaluate left ventricular systolic synchronization, involving 15 from 2D-STI and 8 from RT-3DE. Results Few of the dyssynchrony parametersshowednegative correlations with LV ejection fraction （LVEF） in the CHF group. The difference between time to peak-systolic radial strain of the anteroseptal and posterior segments at the level of papillary muscles [AS-P（RS）] from 2D-STI showed positive correlations with parts of the parameters from RT-3DE （P 〈 0.05）. Conclusions LV systolic dysfunction does not correlate with dyssynchrony. Moreover, there is a weak association between 2D-STI and RT-3DE in assessment of left ventricular dyssynchrony.展开更多
Objective:To investigate the value of two-dimensional ultrasound speckle tracking(2D-STI)and three-dimensional ultrasound speckle tracking(3D-STI)in evaluating myocardial function in children with Kawasaki disease.Met...Objective:To investigate the value of two-dimensional ultrasound speckle tracking(2D-STI)and three-dimensional ultrasound speckle tracking(3D-STI)in evaluating myocardial function in children with Kawasaki disease.Methods 92 children with Kawasaki disease admitted to our hospital from February 2017 to February 2019 were retrospectively analyzed.50 children who underwent 3D-STI examination were taken as observation group and 42 children who underwent 2D-STI examination were taken as control group.The left ventricular systolic function index,storage time and analysis time of the image,the diameter of coronary artery,the strain difference of left ventricular basal segment,middle segment,apical segment and whole segment were observed.Results The levels of left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),left ventricular myocardial mass(LVMI)in the observation group were higher than those in the control group(P<0.05),but there was no statistical difference in left ventricular ejection fraction(LVEF)between the two groups(P>0.05).The storage time and analysis time of the image in the observation group were significantly lower than those in the control group(P<0.05).The left coronary artery(LCA)and right coronary artery(RCA)in the observation group were higher than those in the control group(P<0.05).There was no statistical difference between left anterior descending(LAD)in the two groups(P>0.05).The longitudinal peak systolic strain(LS),circumferential peak systolic strain(CS)and radial peak systolic strain(RS)in the observation group were higher than those in the control group(P<0.05).The global longitudinal peak strain(GLS),global circumferential peak strain(GCS)and global radial peak strain(GRS)in the observation group were higher than those in the control group(P<0.05).LS and CS in the middle segment of the observation group were higher than those in the control group(P<0.05).Conclusions Compared with 2D-STI,3D-STI can objectively and accurately reflect the myocardial function of children with Kawasaki disease.展开更多
Freak waves are commonly characterized by strong-nonlinearity, and the wave steepness, which is calculated from the wavelength, is a measure of the degree of the wave nonlinearity. Moreover, the wavelength can describ...Freak waves are commonly characterized by strong-nonlinearity, and the wave steepness, which is calculated from the wavelength, is a measure of the degree of the wave nonlinearity. Moreover, the wavelength can describe the locally spatial characteristics of freak waves. Generally, the wavelengths of freak waves are estimated from the dispersion relations of Stokes waves. This paper concerns whether this approach enables a consistent estimate of the wavelength of freak waves. The two-(unidirectional, long-crested) and three-dimensional(multidirectional, shortcrested) freak waves are simulated experimentally through the dispersive and directional focusing of component waves, and the wavelengths obtained from the surface elevations measured by the wave gauge array are compared with the results from the linear, 3rd-order and 5th-order Stokes wave theories. The comparison results suggest that the 3rd-order theory estimates the wavelengths of freak waves with higher accuracy than the linear and 5th-order theories. Furthermore, the results allow insights into the dominant factors. It is particularly noteworthy that the accuracy is likely to depend on the wave period, and that the wavelengths of longer period freak waves are overestimated but the wavelengths are underestimated for shorter period ones. In order to decrease the deviation, a modified formulation is presented to predict the wavelengths of two-and three-dimensional freak waves more accurately than the 3rd-order dispersion relation, by regression analysis. The normalized differences between the predicted and experimental results are over 50% smaller for the modified model suggested in this study compared with the 3rd-order dispersion relation.展开更多
Stably stratified flows over a two-dimensional hill are investigated in a channel of finite depth using a three-dimensional direct numerical simulation (DNS). The present study follows onto our previous two-dimensiona...Stably stratified flows over a two-dimensional hill are investigated in a channel of finite depth using a three-dimensional direct numerical simulation (DNS). The present study follows onto our previous two-dimensional DNS studies of stably stratified flows over a hill in a channel of finite depth and provides a more realistic simulation of atmospheric flows than our previous studies. A hill with a constant cross-section in the spanwise (y) direction is placed in a 3-D computational domain. As in the previous 2-D simulations, to avoid the effect of the ground boundary layer that develops upstream of the hill, no-slip conditions are imposed only on the hill surface and the surface downstream of the hill;slip conditions are imposed on the surface upstream of the hill. The simulated 3-D flows are discussed by comparing them to the simulated 2-D flows with a focus on the effect of the stable stratification on the non-periodic separation and reattachment of the flow behind the hill. In neutral (K = 0, where K is a non-dimensional stability parameter) and weakly stable (K = 0.8) conditions, 3-D flows over a hill differ clearly from 2-D flows over a hill mainly because of the three-dimensionality of the flow, that is the development of a spanwise flow component in the 3-D flows. In highly stable conditions (K = 1, 1.3), long-wavelength lee waves develop downstream of the hill in both 2-D and 3-D flows, and the behaviors of the 2-D and 3-D flows are similar in the vicinity of the hill. In other words, the spanwise component of the 3-D flows is strongly suppressed in highly stable conditions, and the flow in the vicinity of the hill becomes approximately two-dimensional in the x and z directions.展开更多
In recent years, with the level of science and technology progress, largely to promote the development of animation techniques. Animated film is divided into two-dimensional animation and three-dimensional animation, ...In recent years, with the level of science and technology progress, largely to promote the development of animation techniques. Animated film is divided into two-dimensional animation and three-dimensional animation, both in the retention feature animated films, based on the performance of each with different strengths, thus forming a different artistic style. Wherein the two-dimensional animation is the most common one is the most basic form of expression in animation technology is relatively mature and complete, but because of the development of animation techniques, two-dimensional animation can not meet the needs of the audience. Thus, the effective combination of two-dimensional animation and three-dimensional animation technology, the advantages of integration between the two is particularly important, so that innovation in the form of screen performance, enhance audio-visual experience. In this paper, two-dimensional animation and three-dimensional animation skills fusion analysis and research, and put forward a number of specific observations, in order to learn.展开更多
To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D lea...To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.展开更多
文摘BACKGROUND Fracture is one of the most pervasive injuries in the musculoskeletal system,and there is a complex interaction between macrophages and adipose tissue-derived stem cells(ADSCs)in fracture healing.However,two-dimensional(2D)coculture of macrophages and ADSCs can not accurately mimic the in vivo cell microenvironment.AIM To establish both 2D and 3D osteogenic coculture models to investigate the interaction between macrophages and ADSCs.METHODS After obtaining ADSCs from surgery and inducing differentiation of the THP1 cell line,we established 2D and 3D osteogenic coculture models.To assess the level of osteogenic differentiation,we used alizarin red staining and measured the relative expression levels of osteogenic differentiation markers osteocalcin,Runt-related transcription factor 2,and alkaline phosphatase through polymerase chain reaction.Verification was conducted by analyzing the expression changes of N-cadherin and the activation of the Wnt/β-catenin signaling pathway using western blotting.RESULTS In this study,it was discovered that macrophages in 3D culture inhibited osteogenic differentiation of ADSCs,contrary to the effect in 2D culture.This observation confirmed the significance of intricate intercellular connections in the 3D culture environment.Additionally,the 3D culture group exhibited significantly higher N-cadherin expression and showed reducedβ-catenin and Wnt1 protein levels compared to the 2D culture group.CONCLUSION Macrophages promoted ADSC osteogenic differentiation in 2D culture conditions but inhibited it in 3D culture.The 3D culture environment might inhibit the Wnt/β-catenin signaling pathway by upregulating N-cadherin expression,ultimately hindering the osteogenic differentiation of ADSCs.By investigating the process of osteogenesis in ADSCs,this study provides novel ideas for exploring 3D osteogenesis in ADSCs,fracture repair,and other bone trauma repair.
基金supported by the NSFC(12474071)Natural Science Foundation of Shandong Province(ZR2024YQ051,ZR2025QB50)+6 种基金Guangdong Basic and Applied Basic Research Foundation(2025A1515011191)the Shanghai Sailing Program(23YF1402200,23YF1402400)funded by Basic Research Program of Jiangsu(BK20240424)Open Research Fund of State Key Laboratory of Crystal Materials(KF2406)Taishan Scholar Foundation of Shandong Province(tsqn202408006,tsqn202507058)Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2024QTB002)the Qilu Young Scholar Program of Shandong University。
文摘As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and electrochemical characteristics,MXenes have shown great potential in brain-inspired neuromorphic computing electronics,including neuromorphic gas sensors,pressure sensors and photodetectors.This paper provides a forward-looking review of the research progress regarding MXenes in the neuromorphic sensing domain and discussed the critical challenges that need to be resolved.Key bottlenecks such as insufficient long-term stability under environmental exposure,high costs,scalability limitations in large-scale production,and mechanical mismatch in wearable integration hinder their practical deployment.Furthermore,unresolved issues like interfacial compatibility in heterostructures and energy inefficiency in neu-romorphic signal conversion demand urgent attention.The review offers insights into future research directions enhance the fundamental understanding of MXene properties and promote further integration into neuromorphic computing applications through the convergence with various emerging technologies.
基金supported by the National Natural Science Foundation of China(Grant Nos.22372142,12304028,12404027)the Foreign Expert Introduction Program(Grant No.G2023003004L)+6 种基金the Central Guiding Local Science and Technology Development Fund Projects(Grant No.236Z7605G)the Natural Science Foundation of Hebei Province(Grant Nos.B2024203051,A2024203023,A2024203002)the Science and Technology Project of Hebei Education Department(Grant No.JZX2023020)the Innovation Capability Improvement Project of Hebei Province(Grant No.22567605H)the Hebei Province Yan Zhao Huang Jin Tai Talent Program(Postdoctoral Platform,Grant No.B2024003003)the financial support from the Spanish Ministry of Science and Innovation(Grant No.PID2022139230NB-I00)the Department of Education,Universities and Research of the Basque Government and the University of the Basque Country(Grant No.IT1707-22)。
文摘Superconductivity in two-dimensional(2D)materials has attracted considerable attention due to their unique physical properties and potential for high-temperature operation.Boron-based 2D compounds are particularly promising,thanks to their structural flexibility and the emergence of strong electron-phonon coupling(EPC)associated with light elements.While most previous studies have focused on stabilizing boron sheets through metal incorporation,we propose an alternative approach based on multicenter bonding enabled by group-IV non-metallic elements(Si,Ge,Sn).The resulting XB_(2)(X=Si,Ge,Sn)monolayers,which adopt a MgB_(2)-like monolayer configuration,are stabilized by a seven-center two-electron(7c-2e)bonding network between the X atoms and the boron honeycomb lattice.This bonding lowers the energy of the B-p_(z)orbitals and enhances lattice stability.The superconducting transition temperature(T_(c))increases significantly with the atomic number of X—from 4.7 K in SiB_(2)to 13.3 K in GeB_(2)and 24.9 K in SnB_(2)—driven by an increased carrier density near the Fermi level(E_(F))and softening of the high-frequency E_(2)phonon mode.Furthermore,we design a SnB_4 monolayer,in which a Sn layer is sandwiched between the two boron layers.This structure enriches in-plane phonon modes and strengthens EPC,yielding a T_(c)of 38 K,close to the McMillan limit.These findings highlight the critical role of multicenter bonding and targeted phonon engineering in enabling high-T_(c)2D boron-based superconductors.
基金supported by the Fundamental Research Funds for the Central Universities(WUT:2024IVA052 and Grant No.104972025KFYjc0089)。
文摘Two-dimensional(2D)multilayer kagome materials hold significant research value for regulating kagome-related physical properties and exploring quantum effects.However,their development is hindered by the scarcity of available material systems,making the identification of novel 2D multilayer kagome candidates particularly important.In this work,three types of 2D materials with trilayer kagome lattices,namely Sc_(6)S_(5)X_(6)(X=Cl,Br,I),are predicted based on first-principles calculations.These 2D materials feature two kagome lattices composed of Sc atoms and one kagome lattice composed of S atoms.Stability analysis indicates that these materials can exist as free-standing 2D materials.Electronic structure calculations reveal that Sc_(6)S_(5)X_(6)are narrow-bandgap semiconductors(0.76–0.95 e V),with their band structures exhibiting flat bands contributed by Sc-based kagome lattices and Dirac band gaps resulting from symmetry breaking.The sulfur-based kagome lattice in the central layer contributes an independent flat band below the Fermi level.Additionally,Sc_(6)S_(5)X_(6)exhibit high carrier mobility,with hole and electron mobilities reaching up to 10^(3)cm^(2)·V^(-1)·s^(-1),indicating potential applications in low-dimensional electronic devices.This work provides an excellent example for the development of novel multilayer 2D kagome materials.
基金support of the National Natural Science Foundation of China(No.12172023)。
文摘According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.
基金Supported by A key medical project in Nanjing Military District of the Chinese People’s Liberation Army,No. 09Z039
文摘AIM： To investigate the value of two-dimensional （2D） and three-dimensional （3D） double contrast-enhanced ultrasonography （DCUS） imaging for evaluation of gas- tric lesions. METHODS： 2D and 3D DCUS imaging with both oral and intravenous administrations of contrast agents was used to assess gastroscopiclly-confirmed gastric lesions in 46 patients with benign and malignant diseases. Initially, liquid-based ultrasound contrast agent （Xinzhang） was given orally at dose of 500-600 mL for conventional ultrasound examination of the gastric lesions, and then a microbubble-based contrast agent （SonoVue） was injected intravenously at dose of 1.2-2.4 mL in bolus fashion to assess the perfusion pattern of the lesions using contrast imaging modes. The parameters derived from time-intensity curves including the arrival time （AT）, time to peak （lq-P）, peak intensity （PI） and en- hanced intensity （EI） were measured on the 2D DCUS imaging. 3D DCUS of the lesions was acquired to dem- onstrate the value of this imaging mode. RESULTS： There were 22 cases with benign lesions including chronic gastritis （n= 5）, gastric ulcer （n = 9）, gastric polyps （n = 3）, gastric stromal tumors （n = 5）, and 24 cases with malignant lesions including gastric cancer （n = 20）, gastric cardia carcinoma （n = 3） and post-operative recurrent gastric cancer （n = 1） in the study, The oral contrast-enhanced ultrasonography （CEUS） imaging of the stomach clearly demonstrated the anatomy of the stomach and morphologic features of gastric lesions, With optimal scanning window and imaging display under oral CEUS, intravenous CEUS clearly showed the perfusion of gastric lesions with various characteristic manifestations. Both 2D and 3D DCUS images clearly demonstrated normal gastric wall as a three-layer structure, from the inside out, hypere- choic mucosa, hypoechoic muscularis and hyperechoic serosa, respectively. There were statistical significant differences of AT （8.68±2.06 vs 10.43 ±2.75, P = 0.017）, PI （34.64 ± 6.63 vs 29.58 ± 8.22, P = 0.023） and EI （29.72 ± 6.69 vs 22.66 ± 7.01, P = 0.001） between malignant lesions and normal gastric wall. However, no differences of AT, PI and EI between benign lesions and normal gastric wall tissue were found. 3D DCUS could intuitively display morphological features and vascularities of the lesions with multiplanar and volume views. 3D DCUS imaging provided comprehen- sive information complementary to 2D imaging. The crater or wellhead appearances and feeding vessels as well as distorted nourishing vasculature of gastric carcinoma were better seen with 3D imaging than 2D imaging. CONCLUSION： DCUS imaging can simultaneouslydisplay the anatomic and perfusion features of gastric lesions. 3D DCUS can provide additional information to 2D DCUS for evaluation of gastric lesions.
文摘AIM: To define the benefits of three-dimensional video-assisted thoracoscopic esophagectomy(3D-VATE)over 2D-VATE for esophageal cancer.METHODS: A total of 93 patients with esophageal cancer including 45 patients receiving 3D-VATE and48 receiving 2D-VATE were evaluated. Data related to patient and cancer characteristics, operating time,intraoperative bleeding, morbidity and mortality,postoperative inflammatory markers, Numerical Rating Scale for postoperative pain, Constant-Murley rating system for shoulder recovery and oxygenation index(OI) were collected. All medical records were retrieved from a prospectively maintained oncological database at our institution. A retrospective study was performed to compare the short-term surgical outcomes between the two groups.RESULTS: No significant differences were found between the two groups in either morbidity or mortality(P = 0.328). An enhanced surgical recovery was noted in the 3D group as indicated by shortened thoracoscopic operation time(3D vs 2D: 68 ± 13.79 min vs 83 ± 13min, P < 0.01), minor intraoperative blood loss(3D vs 2D: 68.2 ± 10.7 ml vs 89.8 ± 10.4 ml, P < 0.01),earlier chest tube removal(3D vs 2D: 2.67 ± 1.01 vs3.75 ± 1.15 d, P < 0.01), shorter length of hospital stay(3D vs 2D: 9.07 ± 2.00 vs 10.85 ± 3.40 d, P <0.01), lower in-hospital expenses(3D vs 2D: 74968.4± 9637.8 vs 86211.1 ± 8519.7 RMB, P < 0.01), lower pain intensity(P < 0.01) and faster recovery of the left shoulder function(P < 0.01). Better preservation of the pulmonary function was also found in the 3D group as the decline of the OI post operation was significantly lower than that of the 2D group(P < 0.01). Changes of postoperative inflammatory markers, including procalcitonin [postoperative days(PODs) 4 and 7: P <0.01], peripheral granulocytes(PODs 1, 4 and 7: P <0.01) and hypersensitive C-reactive protein(POD 4: P< 0.01) in 3D-VATE patients were less than those in the 2D group. Moreover, utilization of the 3D technique extended the dissection of the thoracic lymph nodes(P < 0.01), with better exposure of nodes in the left recurrent laryngeal nerve(P = 0.031).CONCLUSION: 3D-VATE could be a more viable technique over 2D-VATE in terms of short-term outcomes for patients with esophageal cancer.
文摘Summary： This study sought to evaluate the contribution of two-dimensional ultrasound （2D-US） and three-dimensional skeletal imaging ultrasound （3D-SUIS） in the prenatal diagnosis of sirenomelia. Be- tween September 2010 and April 2014, a prospective study was conducted in a single referral center using 3D-SU1S performed after 2D-US in 10 cases of sirenomelia. Diagnostic accuracy and detailed findings were compared with postnatal three-dimensional helical computed tomography （3D-HCT）, radiological findings and autopsy. Pregnancy was terminated in all 10 sirenomelia cases, including 9 singletons and I conjoined twin pregnancy, for a total of 5 males and 5 females. These cases of sirenomelia were deter- mined by autopsy and/or chromosomal examination. Initial 2D-US showed that there were 10 cases of oligohydranmios, bilateral renal agenesis, bladder agenesis, single umbilical artery, fusion of the lower limbs and spinal abnormalities; 8 cases of dipus or monopus; 2 cases of apus; and 8 cases of cardiac abnormalities. Subsequent 3D-SUIS showed that there were 9 cases of scoliosis, l0 cases of sacrococ- cygeal vertebra dysplasia, 3 cases of hemivertebra, 1 case of vertebral fusion, 3 cases of spina bifida, and 5 cases of rib abnormalities. 3D-SUIS identified significantly more skeletal abnormalities than did 2D-US, and its accuracy was 79.5% （70/88） compared with 3D-HCT and radiography. 3D-SUIS seems to be a useful complementary method to 2D-US and may improve the accuracy of identifying prenatal skeletal abnormalities related to sirenomelia.
基金National Natural Science Foundation of China （60904085） New Teachers’ Fund for Doctor Stations of Ministry of Education of China （200802881012）+1 种基金 Excellent Talent Project “Zijin Star” Foundation of Nanjing University of Science and Technology Foundation of National Defence Key Laboratory of Ballistics
文摘Both the design process and form of the three-dimensional （3D） suboptimal guidance law （3DSGL） are very complex. Therefore, we propose the use of two-dimensional （2D） guidance laws to meet the guidance requirements of 3D space. By analyzing the relationship between the flight-path angle and its projections on OXY and OXZ planes, we obtain the ideal design requirements of the guidance laws. Based on the requirements, we design a 2D suboptimal guidance law used in the horizontal plane; combining the 2D vertical suboptimal guidance law, we create a whole ballistic simulation of six degree-of-freedom. The results are compared with those using other three guidance modes in the case of large windage of the initial azimuth angle. When the proportional navigation guidance （PNG） law is used in the horizontal planes, the landing angle will obviously decrease. With the proposed guidance mode, the large landing angle can be realized and meet the guidance precision requirements. Moreover, the required overload can decrease to meet the control requirement. The effects of the proposed guidance mode are close to that of 3DSGL despite its very simple form.
基金substantially supported by the National Natural Science Foundation of China(NSFC)Program(Nos.41972302,41772345)。
文摘Multiple-point statistics(MPS)is a useful approach to reconstruct three-dimensional models in the macroscopic or microscopic field.Extracting spatial features for three-dimensional reconstruction from two-dimensional training images(TIs),and characterizing non-stationary features with directional ductility are two key issues in MPS simulation.This study presents a step-wise MPS-based three-dimensional structures reconstruction algorithm with the sequential process and hierarchical strategy based on two-dimensional images.An extension method is proposed to construct three-dimensional TIs.With a sequential simulation process,an initial guess at the coarsest scale is simulated,in which hierarchical strategy is used according to the characteristics of TIs.To obtain a more refined realization,an expectation-maximization like iterative process with global optimization is implemented.A concrete example of chondrite micro-structure simulation,in which one scanning electron microscopy(SEM)image of the Heyetang meteorite is used as TI,shows that the presented algorithm can simulate complex non-stationary structures.
文摘Three-dimensional(3D)reconstruction of human organs has gained attention in recent years due to advances in the Internet and graphics processing units.In the coming years,most patient care will shift toward this new paradigm.However,development of fast and accurate 3D models from medical images or a set of medical scans remains a daunting task due to the number of pre-processing steps involved,most of which are dependent on human expertise.In this review,a survey of pre-processing steps was conducted,and reconstruction techniques for several organs in medical diagnosis were studied.Various methods and principles related to 3D reconstruction were highlighted.The usefulness of 3D reconstruction of organs in medical diagnosis was also highlighted.
基金The National Natural Science Foundation of China(No.51975117)。
文摘To solve the problem of the lack of comprehensive evaluation of three-dimensional(3D)asphalt pavement roughness,a method for evaluating the asphalt pavement roughness is proposed based on two-dimensional(2D)power spectral density(PSD).By calculating the 2D PSD of a 3D asphalt pavement and converting it into the longitudinal average asphalt pavement PSD,the relationship between the evaluation method of the 3D asphalt pavement roughness and the current evaluation standard of roughness is established.Combined with the road-fitting formula used in international standards,the elevation data of the A,B,C,and D grades of the 3D asphalt pavement are simulated by the harmonic superposition method.According to the proposed method,the longitudinal PSD of each level of simulated asphalt pavement is calculated and compared with the standard spectral line of each pavement level.This approach verifies the effectiveness of the proposed method in evaluating the roughness of the 3D asphalt pavement.Compared with the PSD of a certain horizontal profile elevation,it is verified that the fluctuation amplitude of the spectral line calculated by the proposed method is greatly improved.The results show that the proposed method can evaluate the roughness of asphalt pavements more comprehensively and accurately and has strong practicability.
基金financially supported by the National Science Foundation of China(Nos.51572007 and 51622203),"Recruitment Program of Global Experts"
文摘2D nanosheets such as graphene, silicene, phosphorene, metal dichalcogenides and MXenes are emerging and promising for lithium storage due to their ultrathin nature and corresponding chemical/physical properties. However, the serious restacking and aggregation of the 2D nanosheets are still hampering their applications. To circumvent the issues of 2D nanosheets, one efficient strategy is to construct 3D structures with hierarchical porous structures, good chemical/mechanical stabilities and tunable electrical conductivities. In this review, we firstly focus on the available synthetic approaches of 3D structures from 2D nanosheets, and then summarize the relationships between the microstructures of 3D structures built from 2D nanosheets and their electrochemical behaviors for lithium storage. On the basis of above results, some challenges are briefly discussed in the perspective of the development of various functional 3D structures.
文摘Background Two-dimensional speckle tracking imaging （2D-STI） and real-time three-dimensional echocardiography （RT-3DE） have more advantages in evaluating left ventricular （LV） systolic dyssynchrony than traditional echocardiographic techniques. The study aimed to evaluate LV dyssynchrony parameters by both 2D-STI and RT-3DE, and the correlation between these two techniques. Methods A total of 43 chronic heart failure （CHF） patients and 27 healthy volunteers were enrolled. There were 23 dyssynchrony parameters selected to evaluate left ventricular systolic synchronization, involving 15 from 2D-STI and 8 from RT-3DE. Results Few of the dyssynchrony parametersshowednegative correlations with LV ejection fraction （LVEF） in the CHF group. The difference between time to peak-systolic radial strain of the anteroseptal and posterior segments at the level of papillary muscles [AS-P（RS）] from 2D-STI showed positive correlations with parts of the parameters from RT-3DE （P 〈 0.05）. Conclusions LV systolic dysfunction does not correlate with dyssynchrony. Moreover, there is a weak association between 2D-STI and RT-3DE in assessment of left ventricular dyssynchrony.
基金Shaanxi key research and development plan(No.2019SF-211).
文摘Objective:To investigate the value of two-dimensional ultrasound speckle tracking(2D-STI)and three-dimensional ultrasound speckle tracking(3D-STI)in evaluating myocardial function in children with Kawasaki disease.Methods 92 children with Kawasaki disease admitted to our hospital from February 2017 to February 2019 were retrospectively analyzed.50 children who underwent 3D-STI examination were taken as observation group and 42 children who underwent 2D-STI examination were taken as control group.The left ventricular systolic function index,storage time and analysis time of the image,the diameter of coronary artery,the strain difference of left ventricular basal segment,middle segment,apical segment and whole segment were observed.Results The levels of left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),left ventricular myocardial mass(LVMI)in the observation group were higher than those in the control group(P<0.05),but there was no statistical difference in left ventricular ejection fraction(LVEF)between the two groups(P>0.05).The storage time and analysis time of the image in the observation group were significantly lower than those in the control group(P<0.05).The left coronary artery(LCA)and right coronary artery(RCA)in the observation group were higher than those in the control group(P<0.05).There was no statistical difference between left anterior descending(LAD)in the two groups(P>0.05).The longitudinal peak systolic strain(LS),circumferential peak systolic strain(CS)and radial peak systolic strain(RS)in the observation group were higher than those in the control group(P<0.05).The global longitudinal peak strain(GLS),global circumferential peak strain(GCS)and global radial peak strain(GRS)in the observation group were higher than those in the control group(P<0.05).LS and CS in the middle segment of the observation group were higher than those in the control group(P<0.05).Conclusions Compared with 2D-STI,3D-STI can objectively and accurately reflect the myocardial function of children with Kawasaki disease.
基金financially supported by the National Natural Science Foundation of China (Grant Nos.51509120 and 52171260)the Basic Funding of the Central Public Research Institutes (Grant No.TKS20200317)。
文摘Freak waves are commonly characterized by strong-nonlinearity, and the wave steepness, which is calculated from the wavelength, is a measure of the degree of the wave nonlinearity. Moreover, the wavelength can describe the locally spatial characteristics of freak waves. Generally, the wavelengths of freak waves are estimated from the dispersion relations of Stokes waves. This paper concerns whether this approach enables a consistent estimate of the wavelength of freak waves. The two-(unidirectional, long-crested) and three-dimensional(multidirectional, shortcrested) freak waves are simulated experimentally through the dispersive and directional focusing of component waves, and the wavelengths obtained from the surface elevations measured by the wave gauge array are compared with the results from the linear, 3rd-order and 5th-order Stokes wave theories. The comparison results suggest that the 3rd-order theory estimates the wavelengths of freak waves with higher accuracy than the linear and 5th-order theories. Furthermore, the results allow insights into the dominant factors. It is particularly noteworthy that the accuracy is likely to depend on the wave period, and that the wavelengths of longer period freak waves are overestimated but the wavelengths are underestimated for shorter period ones. In order to decrease the deviation, a modified formulation is presented to predict the wavelengths of two-and three-dimensional freak waves more accurately than the 3rd-order dispersion relation, by regression analysis. The normalized differences between the predicted and experimental results are over 50% smaller for the modified model suggested in this study compared with the 3rd-order dispersion relation.
文摘Stably stratified flows over a two-dimensional hill are investigated in a channel of finite depth using a three-dimensional direct numerical simulation (DNS). The present study follows onto our previous two-dimensional DNS studies of stably stratified flows over a hill in a channel of finite depth and provides a more realistic simulation of atmospheric flows than our previous studies. A hill with a constant cross-section in the spanwise (y) direction is placed in a 3-D computational domain. As in the previous 2-D simulations, to avoid the effect of the ground boundary layer that develops upstream of the hill, no-slip conditions are imposed only on the hill surface and the surface downstream of the hill;slip conditions are imposed on the surface upstream of the hill. The simulated 3-D flows are discussed by comparing them to the simulated 2-D flows with a focus on the effect of the stable stratification on the non-periodic separation and reattachment of the flow behind the hill. In neutral (K = 0, where K is a non-dimensional stability parameter) and weakly stable (K = 0.8) conditions, 3-D flows over a hill differ clearly from 2-D flows over a hill mainly because of the three-dimensionality of the flow, that is the development of a spanwise flow component in the 3-D flows. In highly stable conditions (K = 1, 1.3), long-wavelength lee waves develop downstream of the hill in both 2-D and 3-D flows, and the behaviors of the 2-D and 3-D flows are similar in the vicinity of the hill. In other words, the spanwise component of the 3-D flows is strongly suppressed in highly stable conditions, and the flow in the vicinity of the hill becomes approximately two-dimensional in the x and z directions.
文摘In recent years, with the level of science and technology progress, largely to promote the development of animation techniques. Animated film is divided into two-dimensional animation and three-dimensional animation, both in the retention feature animated films, based on the performance of each with different strengths, thus forming a different artistic style. Wherein the two-dimensional animation is the most common one is the most basic form of expression in animation technology is relatively mature and complete, but because of the development of animation techniques, two-dimensional animation can not meet the needs of the audience. Thus, the effective combination of two-dimensional animation and three-dimensional animation technology, the advantages of integration between the two is particularly important, so that innovation in the form of screen performance, enhance audio-visual experience. In this paper, two-dimensional animation and three-dimensional animation skills fusion analysis and research, and put forward a number of specific observations, in order to learn.
文摘To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.
