Geographic,Geometrical and Semantic Reconstruction of Urban Scene from High Resolution Oblique Aerial Images

An effective approach is proposed for 3D urban scene reconstruction in the form of point cloud with semantic labeling. Starting from high resolution oblique aerial images,our approach proceeds through three main stages: geographic reconstruction, geometrical reconstruction and semantic reconstruction. The absolute position and orientation of all the cameras relative to the real world are recovered in the geographic reconstruction stage. Then, in the geometrical reconstruction stage,an improved multi-view stereo matching method is employed to produce 3D dense points with color and normal information by taking into account the prior knowledge of aerial imagery.Finally the point cloud is classified into three classes(building,vegetation, and ground) by a rule-based hierarchical approach in the semantic reconstruction step. Experiments on complex urban scene show that our proposed 3-stage approach could generate reasonable reconstruction result robustly and efficiently.By comparing our final semantic reconstruction result with the manually labeled ground truth, classification accuracies from86.75% to 93.02% are obtained.

Oxidation of a Co-base Superalloy

The oxidation behavior of a cast polycrystalline Co-base superalloy was studied at temperatures from 900 to 1050℃ and analyzed by thermogravimetric analysis （TGA）, X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results indicate that a cast Co-base superalloy follows the subparabolic oxidation kinetics at 900 and 1000℃, which are controlled by the growth of the inner Cr-rich layer, and that after oxidation at 1050℃ for 200 h, it almost exhibits the linear oxidation kinetics possible due to the volatility of Cr-rich oxide. A mixed scale forms on the alloy after prolonged oxidation. The oxide scale formed at 900 and 1000℃ is composed of an outer layer of spinel and an inner continuous Cr-rich layer and at I050℃ is composed of a very discontinuous Cr-rich layer.

A Banding Structure in a Ni-Cu-Si Cast Alloy

The solidified microstructure of a Ni-Cu-Si cast alloy has been investigated, and a kind of banding structure was observed. The results showed that, the banding structure was composed of coarser particles which were Ni3Si type of precipitates and similar to the fine particles precipitate uniformly distributed within matrix of Ni solid solution, in both crystal structure and composition. The formation of bandings was resulted from cast thermal stress and dislocation walls. It was found that the cracks propagated along these bandings in tensile test. The banding structure can be depressed by reducing the cast thermal stress, which can improve the tensile ductility.

Considerations on Research of Environmental Risk Prevention and Control in “12th Five-Year Plan” Period

Along with the environmental pollution causes complexity and diversity increases ceaselessly, “national environmental protection” Twelfth Five “planning” (hereinafter referred to as “planning”) will be the environmental risk prevention as the “12th Five-Year Plan” one of the important tasks, including advancing environmental risk management in the whole process, key areas the environmental risk prevention measures. The whole process environmental risk management covers a risk source recognition, receptor vulnerability assessment, environmental risk characterization, risk decision and risk assessment of accident loss. This article from the environmental risk source classification, environmental risk classification management, environmental emergency response and environmental risk and insurance environment four aspects put forward the “12th Five-Year Plan” whole process environmental risk management content, to further reduce our country environmental pollution accident risk and policy makers to provide some decision support.

Safety and feasibility of ultra-early lumbar puncture in patients with aneurysmal subarachnoid hemorrhage

Objective:to evaluate the clinical efficacy and safety of ultra-early lumbar puncture drainage of cerebrospinal fluid(CSF)in patients with aneurysmal subarachnoid hemorrhage(SAH).Methods:patients(n=140)with aneurysmal SAH were randomly divided into observation group(n=70)and control group(n=70).After admission,CSF was drained by ultra-early lumbar puncture in the observation group and intermittent lumbar puncture after aneurysm operation in the control group.The incidences of early aneurysm rupture,acute hydrocephalus and delayed hydrocephalus were compared between the two groups.Results:there was no significant diflerence in the incidence of early-ruptured aneurysm and acute hydrocephalus between the two groups,but the incidence of delayed hydrocephalus in the observation group was significantly lower than that in the control group.Conclusion:ultra-early lumbar puncture drainage of CSF in anexirysmal SAH can effectively reduce the incidence of long-term delayed hydrocephalus and it is a safe and effective treatment.

Comparison of two surgical approaches for petroclinic lesions

Objective:to compare the methods of petrous apical bone removal and to explore the applicable scope of Kawase approach and retrosigmoid sinus-internal auditory canal approach.Methods:one group of cadaveric head specimens simulated Kawase approach to measure the data of“Kawase triangle”,the other group simulated retrosigmoid sinus-internal auditory canal approach to measure the safety range of the grinding bone window.Then we explored the clinical indications of the two surgical approaches.Result:the grinding depth of Kawase triangle was 11.6±0.14 mm,and the range of clival exposed after grinding Kawase triangle was 22.4±1.22 mm,which could effectively expose the ventrolateral brainstem,the midline of clivus and the area above the facial acoustic nerve.The diameter of the anterior and posterior of the grinding bone window in the retrosigmoid sinus-internal auditory canal approach was 21.95±2.23 mm.In front of the exposure area were the internal carotid artery,the cavernous sinus,and the upper trigeminal nerve;the lower part was the connection between the facial acoustic nerve and the abducent nerve.Conclusion:Kawase approach is suitable for lesions of ventrolateral brainstem,middle superior clivus,with or without invasion of middle cranial fossa;the retrosigmoid sinus-superior internal auditory canal approach is suitable for lesions mainly in cerebellopontine angle area and only slightly invading Meckel’s cavity.

Effect of improving prehospital hypotension and hypoxemia on the prognosis of patients with traumatic brain injury

Objective:to investigate the effect of improving prehospital hypotension and hypoxemia on the prognosis of different subgroups of patients with traumatic brain injury(TBI).Methods:medical staff were trained about the prehospital first aid for 2 months to fully master the methods of improving prehospital hypotension and hypoxemia,then the prognosis of TBI patients pre-and post-training for 12 months was collected and recorded.The prognostic differences of different TBI subgroups were discussed through data analysis.Results:after the training,the proportion of prehospital hypotension and hypoxemia in TBI patients decreased by 77%(8.5%vs.1.9%)and 63%(9.9%vs.3.6%,P<0.05),respectively.However,only the prognosis of moderate and severe TBI patients was improved,the proportion of patients with"good prognosis^increased by 14%(61.4%vs.70.5%,respectively)and 62%(35.6%vs.58%),and no significant effect showed in mild and critical TBI patients.Conclusion:reducing the incidence of prehospital hypoxemia and hypotension can improve the prognosis of moderate and severe TBI patients,while no significant effect on mild and critical TBI patients.

A 6n-Order Low-Frequency Mathematical Model of Multiple Inverters Based Microgrid

Microgrid stability analysis is a critical issue especially due to the inverters’low-inertia nature.The voltage and current control loops influences on stability are researched frequently most of which focus on medium and high-frequency characteristic.Although the complete state-space model aims at low-frequency characteristic,it is too complicated and the calculation amount is huge with the scale of the microgrid increasing.One available reduced-order model of an inverter is simple,but it is suitable for only single inverter without network dynamic in microgrid.To fill in these gaps,a novel modeling method is proposed in this paper to investigate the low-frequency instability phenomenon and describe the whole DG connected system including network.In consideration of the high penetration level of induction motor(IM)loads and constant power(CP)loads in practical applications,the low-frequency mathematical model of IM and CP loads on the basis of static load is also built in this paper.Simulation and experimental results verify the effectiveness of the proposed model.

Thermal shock resistant 3D printed ceramics reinforced with MgAl_(2)O_(4) shell structure

The demand for the swirl nozzle with enhanced temperature resistance and lightweight properties is in-creasing as the thrust-to-weight ratio of aero-engines rises.The Al_(2)O_(3) ceramic swirl nozzle can maintain high strength in a hostile environment of high temperature and severe corrosion,while also meeting the requirements of aircraft to enhance efficiency and decrease weight.However,Al_(2)O_(3) ceramics are limited in their application for aerospace components due to their poor thermal shock resistance(TSR)stemming from their inherent brittleness.This work reported an innovative design and fabrication strategy based on photopolymerization 3D printing technology to realize the three-dimensional shell structure through element interdiffusion and nanoscale stacking of the reinforced phase.With this strategy,a novel type of the new dual-structure Al_(2)O_(3) ceramic composed of MgAl_(2)O_(4) shell structure and matrix could be con-structed in situ.The nano-sized MgAl_(2)O_(4) caused a crack passivation effect after the thermal shock,which could improve the strength and TSR of 3D-printed Al_(2)O_(3) ceramic.In addition,the effects of MgO content and sintering temperature on sintering behavior,flexural strength,porosity,and TSR of Al_(2)O_(3) ceram-ics manufactured by digital light processing(DLP)processing were systematically studied.The optimum overall performance of Al_(2)O_(3) ceramics was obtained at the sintering temperature of 1550℃and the MgO content of 1.0 wt.%,with a maximum flexural strength of 111.929 MPa and a critical temperature difference of 374.24℃for TSR.Based on the above research,an aero-engine swirl nozzle with high ther-mal shock resistance has been successfully prepared by ceramic 3D printing technology,which enhances high-temperature resistance and promotes lightweight design in aero-engine.

Carbon dot-based artificial light-harvesting systems with sequential energy transfer and white light emission for photocatalysis

In this work, we designed and synthesized cationic carbon dots(CDs) with a size distribution of 1.6–3.7 nm, which exhibited dark blue fluorescence in the aqueous solution. Based on its excellent luminescence properties, we used it as an energy donor to construct a sequential artificial light-harvesting system(LHS) by employing the energy-matching dyes eosin Y disodium salt(EY) and sulforhodamine101(SR101), which could regulate the white light emission(Commission Internationale de l'Eclairage(CIE) coordinate:(0.30, 0.31)) with the energy transfer efficiency(ΦET) of 53.9% and 20.0%. Moreover, a single-step artificial LHS with white light emission(0.32, 0.28) can be constructed directly using CDs and dye solvent 43(SR) with ΦETand antenna effect(AE) of 48.8% and 6.5, respectively. More importantly,CDs-based artificial LHSs were firstly used in photocatalytic of α-bromoacetophenone, with a yield of90%. This work not only provides a new strategy for constructing CDs-based LHSs, but also opens up a new application for further applying the energy harvested in CDs-based LHSs to the field of the aqueous solution photocatalysis.

Reference values of carotid intima-media thickness and arterial stiffness in Chinese adults based on ultrasound radio frequency signal:A nationwide,multicenter study

Background:Carotid intima-media thickness(IMT)and diameter,stiffness,and wave reflections,are independent and important clinical biomarkers and risk predictors for cardiovascular diseases.The purpose of the present study was to establish nationwide reference values of carotid properties for healthy Chinese adults and to explore potential clinical determinants.Methods:A total of 3053 healthy Han Chinese adults(1922 women)aged 18-79 years were enrolled at 28 collaborating tertiary centers throughout China between April 2021 and July 2022.The real-time tracking of common carotid artery walls was achieved by the radio frequency(RF)ultrasound system.The IMT,diameter,compliance coefficient,βstiffness,local pulse wave velocity(PWV),local systolic blood pressure,augmented pressure(AP),and augmentation index(AIx)were then automatically measured and reported.Data were stratified by age groups and sex.The relationships between age and carotid property parameters were analyzed by Jonckheere-Terpstra test and simple linear regressions.The major clinical determinants of carotid properties were identified by Pearson’s correlation,multiple linear regression,and analyses of covariance.Results:All the parameters of carotid properties demonstrated significantly age-related trajectories.Women showed thinner IMT,smaller carotid diameter,larger AP,and AIx than men.Theβstiffness and PWV were significantly higher in men than women before forties,but the differences reversed after that.The increase rate of carotid IMT(5.5µm/year in women and 5.8µm/year in men)and diameter(0.03 mm/year in both men and women)were similar between men and women.For the stiffness and wave reflections,women showed significantly larger age-related variations than men as demonstrated by steeper regression slopes(all P for age by sex interaction<0.05).The blood pressures,body mass index(BMI),and triglyceride levels were identified as major clinical determinants of carotid properties with adjustment of age and sex.Conclusions:The age-and sex-specific reference values of carotid properties measured by RF ultrasound for healthy Chinese adults were established.The blood pressures,BMI,and triglyceride levels should be considered for clinical application of corresponding reference values.

Non-synchronous vibration of rotor blade in a six-stage transonic compressor

This paper presents an experimental study on the Non-Synchronous Vibration(NSV)in a six-stage transonic compressor.The first part of the paper describes the NSV phenomenon of Rotor 1,which occurs when both Stator 1(S1)and Stator 2(S2)or S1 only are closed.Detailed measurements and analysis are carried out for the former case through the unsteady wall pressure and the Blade Strain(BS).The spinning mode theory used in the rotor/stator interaction noise is employed to explain the relation between the circumferential wave number of the aerodynamic disturbance and the Nodal Diameter(ND)of the blade vibration.The variations of the vibration amplitudes of different blades and the Inter-Blade Phase Angles(IBPAs)at different moments suggest that the evolution of NSV is a highly nonuniform phenomenon along the circumferential direction.In addition,the difference between the wall-pressure spectra generated by the NSV and the classic flutter has been discussed.In the second part,the variations of aerodynamic loading due to the adjustment of the staggers of the Inlet Guide Vane(IGV),S1 and S2 have been investigated.It is found that closing S1 only can result in a great fluctuation to the performance of the front stages,which might be detrimental to the flow organization and increase the risk of NSV.In contrast,the effect of closing S2 only on the performance of the first two stages appears to be slighter relatively.

Theoretical model of azimuthal combustion instability subject to non-trivial boundary conditions

The problem of evaluating the sensitivity of non-trivial boundary conditions to the onset of azimuthal combustion instability is a longstanding challenge in the development process of modern gas turbines.The difficulty lies in how to describe three-dimensional in-and outlet boundary conditions in an artificial computational domain.To date,the existing analytical models have still failed to quantitatively explain why the features of the azimuthal combustion instability of a combustor in laboratory environment are quite different from that in a real gas turbine,making the stability control devices developed in laboratory generally lose the effectiveness in practical applications.To overcome this limitation,we provide a novel theoretical framework to directly include the effect of non-trivial boundary conditions on the azimuthal combustion instability.A key step is to take the non-trivial boundary conditions as equivalent distributed sources so as to uniformly describe the physical characteristics of the inner surface in an annular enclosure along with different in-and outlet configurations.Meanwhile,a dispersion relation equation is established by the application of three-dimensional Green's function approach and generalized impedance concept.Results show that the effects of the generalized modal reflection coefficients on azimuthal unstable modes are extremely prominent,and even prompt the transition from stable to unstable mode,thus reasonably explaining why the thermoacoustic instability phenomena in a real gas turbine are difficult to observe in an isolated combustion chamber.Overall,this work provides an effective tool for analysis of the azimuthal combustion instability including various complicated boundary conditions.

Effect of wire mesh casing treatment on axial compressor performance and stability

In this paper,a kind of Wire Mesh Casing Treatment(WMCT)is proposed to improve the stable operating range of the compressor.In contrast to the traditional circumferential groove,as for WMCT,a layer of wire mesh is laid on the surface of the circumferential groove.Parametric studies were conducted on the low-speed axial flow compressor,including the groove width,axial location,and mesh count.The optimum axial location for WMCT is related to its groove width.A higher wire mesh count results in a smaller compressor stall margin improvement.Steady simulations were carried out to study the effect of WMCT on the flow structure of the compressor.The wire mesh in the WMCT has a certain flow resistance,which restricts the flow into and out of the groove.Due to the WMCT,the flow parameter in the tip region of the rotor is less sensitive to changes in the operating conditions of the compressor.The WMCT causes the rotor tip blade loading to shift backward,inhibiting the formation of spill forward of the leakage flow,and thus improving the stability of the compressor.The flow resistance on the groove surface is a new degree-of-freedom for the casing treatment designer.

Effect of fore/aft-loaded rotor on compressor stability under inlet circumferential distortion

A modified small perturbation stability prediction model for axial compressors with circumferential inlet distortions is established and applied to investigate the effect of fore/aft-loaded rotor on compressor stability under circumferentially distorted inlet conditions.The inlet total pressure distribution downstream of the distortion screen is measured in experiments and employed for simulations which are implemented via time-space spectral method.The stall inception prediction results via the stability model indicate that the compressor with aft-loaded rotor not only performs better in terms of stability under uniform inlet,but also maintains a larger stability margin under circumferentially distorted inlet.The experiments for compressors with fore-loaded and aft-loaded rotor are respectively carried out.The results validate the reliability of numerical simulations and the predicted conclusion that the aft-loaded rotor is beneficial for compressor stability.Besides,the ability of the developed theoretical model for compressor stability prediction under circumferential distortions is confirmed.In addition,dynamic pressure signals at rotor tip measured in experiments illustrate that the circumferential distortion has little effect on the compressor stall pattern.

Effect of Ta on Tensile Behavior and Deformation Mechanism of a Nickel-Based Single Crystal Superalloy

The effects of Ta on the tensile behavior and deformation mechanisms of a Ni-based single crystal superalloy were investigated in this study from room temperature to elevated temperature.The findings demonstrated that the higher content of Ta could improve the tensile properties of the alloy at different temperatures.Due to the different deformation mechanisms at various temperatures,the influence of Ta on tensile deformation varied.At room temperature,the higher content of Ta enhanced the solid solution strengthening,which would enhance the tensile strength of 6.5Ta alloy.After standard heat treatment of 6.5Ta alloy,precipitation of the secondaryγʹphase would hinder the movement of dislocations.When the temperature was elevated to 760℃,the higher content of Ta not only promoted the interaction of stacking faults to form Lomer-Cottrell(L-C)locks that impeded dislocation motion,but also reduced the occurrence of dislocation pile-up groups,thus enhancing the yield strength.At 1120℃,due to the narrowerγchannels and higher APB energy inγʹphase of the alloy with higher Ta addition,the processes of bypassing and shearing of dislocations were hindered,respectively.Meanwhile,the denser and more regular dislocation networks were formed in 6.5Ta alloy;and thus,the tensile strength of 6.5Ta alloy was enhanced.This study systematically investigated the effect of Ta on the tensile behavior at three different temperatures,which provided an important theoretical basis for the design of nickel-based single crystal superalloys in the future.

Hot Deformation Behavior and Workability of a New Ni–W–Cr Superalloy for Molten Salt Reactors

The hot deformation behavior of a newly developed Ni–W–Cr superalloy for use in 800℃molten salt reactors(MSRs)was looked into by isothermal compression tests in the temperature range of 1050–1200℃with a strain rate of 0.001–1 s^(−1)under a true strain of 0.693.An Arrhenius-type model for the Ni–W–Cr superalloy was constructed by fitting the corrected flow stress data.In this model,the effect of dispersion of solid solution elements during thermal deformation on microstructure evolution was considered,as well as the effects of friction and adiabatic heating on the temperature and strain rate-dependent variation of flow stresses.The hot deformation activation energy of the Ni–W–Cr superalloy was 323 kJ/mol,which was less than that of the Hastelloy N alloy(currently used in MSRs).According to the rectified flow stress data,processing maps were created.In conjunction with the corresponding deformation microstructures,the flow instability domains of the Ni–W–Cr superalloy were determined to be 1050–1160℃/0.03–1 s^(−1)and 1170–1200℃/0.001–0.09 s^(−1).In these deformation conditions,a locally inhomogeneous microstructure was caused by flow-i.e.,incomplete dynamic recrystallization and hot working parameters should avoid sliding into these domains.The ideal processing hot deformation domain for the Ni–W–Cr superalloy was determined to be 1170–1200℃/0.6–1 s^(−1).

Limits of Uneven Battery Power in Modular Multilevel Converter-based Battery Energy Storage Systems

For modular multilevel converter-based battery energy storage systems (MMC-BESS), uneven power among batteries of SMs will be deduced by battery aging, battery fault, etc., which will degrade performance and even lead to system failure. For maintaining the balance of capacitor voltage, this paper analyzes the limits of the uneven power of batteries, which are presented as the current limits in this paper. According to analysis, an analytical method is proposed that only the dc and fundamental frequency components of the arm current are used to calculate current limits. With the current limits it is able to evaluate the reasonability of power distribution among batteries. Meanwhile, increase of fundamental frequency component will enhance the current limits, and the dc component determines the size relationship between the absolute values of the upper and lower current limits. Finally, simulation model and experiment prototype are built for verifying the theoretical analysis and current limits calculation method, and satisfactory results are provided.

Influence of Substituting W for Nb or Hf on Solidification Behavior of a Typical Co-Ni-Al-W Based Superalloy

Understanding the effects of various elements on solidification behavior is crucial for designing the composition ofγ’-strengthened Co-based superalloys and is fundamental for controlling the as-cast structure and formulating subsequent heat treatment processes.This research investigated the effects of replacing 1 at.%W with 1 at.%Nb or Hf elements on the solidification behavior of Co-Ni-Al-W-based superalloys.The findings revealed that substituting W with Nb and Hf resulted in a notable decrease in both the solidus temperature(TS)and liquidus temperature(TL).Specifically,the substitution of W with Nb lowered TS from 1353℃ to 1332℃ and TL from 1383℃ to 1368℃,while replacing W with Hf decreased TS from 1353℃ to 1330℃ and TL from 1383℃ to 1366℃.Moreover,both Nb and Hf element are positive segregation element,while Nb decreases and Hf increases W segregation,respectively.During the final solidification stage,the substitution of W with Nb resulted in the formation of eutectic(γ+γ’),Co_(3)Ta,and a small amount ofμ-Co7Nb6 phase,while replacing W with Hf resulted in the formation of the Laves phase andβ-CoAl phase.The solidification paths of the three alloys were confirmed based on the result of differential scanning calorimetry,isothermal solidification experiment and Thermo-calc simulation.These results offer a theoretical basis for the composition design and optimization of heat treatment processes for Co-Ni-Al-W-based superalloys.

Irinotecan hydrochloride liposome HR070803 in combination with 5-fluorouracil and leucovorin in locally advanced or metastatic pancreatic ductal adenocarcinoma following prior gemcitabine-based therapy (PAN-HEROIC-1): a phase 3 trial

Liposomal irinotecan has shown promising antitumor activity in patients with advanced or metastatic pancreatic ductal adenocarcinoma (PDAC) who have undergone prior gemcitabine-based therapies. This randomized, double-blind, parallel-controlled, multicenter phase 3 study (NCT05074589) assessed the efficacy and safety of liposomal irinotecan HR070803 combined with 5-fluorouracil (5-FU) and leucovorin (LV) in this patient population. Patients with unresectable, locally advanced, or metastatic PDAC who had previously received gemcitabine-based therapies were randomized 1:1 to receive either HR070803 (60 mg/m^(2) anhydrous irinotecan hydrochloride, equal to 56.5 mg/m^(2) free base) or placebo, both in combination with 5-FU (2000 mg/m^(2)) and LV (200 mg/m^(2)), all given intravenously every two weeks. The primary endpoint of the study was overall survival (OS). A total of 298 patients were enrolled and received HR070803 plus 5-FU/LV (HR070803 group, n = 149) or placebo plus 5-FU/LV (placebo group, n = 149). Median OS was significantly improved in the HR070803 group compared to the placebo group (7.4 months [95% CI 6.1–8.4] versus 5.0 months [95% CI 4.3–6.0];HR 0.63 [95% CI 0.48–0.84];two-sided p = 0.0019). The most common grade ≥ 3 adverse events in the HR070803 group were increased gamma-glutamyltransferase (19.0% versus 11.6% in placebo group) and decreased neutrophil count (12.9% versus 0 in placebo group). No treatment-related deaths occurred in the HR070803 group, while the placebo group reported one treatment-related death (abdominal infection). HR070803 in combination with 5-FU/LV has shown promising efficacy and manageable safety in advanced or metastatic PDAC in the second-line setting, representing a potential option in this patient population.