Performance validation of High Mountain Asia 8-meter Digital Elevation Model using ICESat-2 geolocated photons

High Mountain Asia(HMA),recognized as a third pole,needs regular and intense studies as it is susceptible to climate change.An accurate and high-resolution Digital Elevation Model(DEM)for this region enables us to analyze it in a 3D environment and understand its intricate role as the Water Tower of Asia.The science teams of NASA realized an 8-m DEM using satellite stereo imagery for HMA,termed HMA 8-m DEM.In this research,we assessed the vertical accuracy of HMA 8-m DEM using reference elevations from ICESat-2 geolocated photons at three test sites of varied topography and land covers.Inferences were made from statistical quantifiers and elevation profiles.For the world’s highest mountain,Mount Everest,and its surroundings,Root Mean Squared Error(RMSE)and Mean Absolute Error(MAE)resulted in 1.94 m and 1.66 m,respectively;however,a uniform positive bias observed in the elevation profiles indicates the seasonal snow cover change will dent the accurate estimation of the elevation in this sort of test sites.The second test site containing gentle slopes with forest patches has exhibited the Digital Surface Model(DSM)features with RMSE and MAE of 0.58 m and 0.52 m,respectively.The third test site,situated in the Zanda County of the Qinghai-Tibet,is a relatively flat terrain bed,mostly bare earth with sudden river cuts,and has minimal errors with RMSE and MAE of 0.32 m and 0.29 m,respectively,and with a negligible bias.Additionally,in one more test site,the feasibility of detecting the glacial lakes was tested,which resulted in exhibiting a flat surface over the surface of the lakes,indicating the potential of HMA 8-m DEM for deriving the hydrological parameters.The results accrued in this investigation confirm that the HMA 8-m DEM has the best vertical accuracy and should be of high use for analyzing natural hazards and monitoring glacier surfaces.

Comparative Skin Histology of Frogs Reveals High-elevation Adaptation of the Tibetan Nanorana parkeri

Adaptations to extreme environmental conditions are intriguing. Animal skin, which directly interacts with external environment, plays diverse and important roles in adaptive evolution. The thin and bare skin of amphibians is sensitive to external environmental conditions and, thus, it facilitates investigations into adaptations for living in extreme environments. Herein, we compare the structures of skin in four anuran species living at elevations ranging from 100 m to 4500 m to assess phenotypic innovations in the skin of Nanorana parkeri, which lives at extremely high elevations. Analyses reveal similar basic skin structures, but N. parkeri differs from the other species by having more epidermal capillaries and granular glands, which correlate highly with responses to hypoxia and/or ultraviolet(UV) radiation. Further intraspecific comparisons from frogs taken at ~4500 m and ~2900 m reveal that all of the changes are fixed. Changes occurring only in the higher elevation population, such as possessing more skin pigments, may represent local adaptations to coldness and/or UV radiation. These results provide a morphological basis for understanding further the molecular adaptations of these frogs.

Characterization of local chemical ordering and deformation behavior in high entropy alloys by transmission electron microscopy

Short-range ordering(SRO)is one of the most important structural features of high entropy alloys(HEAs).However,the chemical and structural analyses of SROs are very difficult due to their small size,complexed compositions,and varied locations.Transmission electron microscopy(TEM)as well as its aberration correction techniques are powerful for characterizing SROs in these compositionally complex alloys.In this short communication,we summarized recent progresses regarding characterization of SROs using TEM in the field of HEAs.By using advanced TEM techniques,not only the existence of SROs was confirmed,but also the effect of SROs on the deformation mechanism was clarified.Moreover,the perspective related to application of TEM techniques in HEAs are also discussed.

Magnitude and Trends of High-elevation Cloud Water Pollutant Concentrations and Modeled Deposition Fluxes

Cloud water samples, LWC （Liquid Water Content） and meteorological data were collected at the Clingmans Dome, Tennessee, high-elevation site in Great Smoky Mountains National Park during the warm season from 1994 through 2011. This paper presents results from 2000 through the conclusion of the study in 2011. Samples were analyzed for SO42＂, NO3, NH4＋ and H＋. These measurements were supplemented by measurements of ambient air and precipitation concentrations to estimate dry and wet deposition. Cloud water concentrations, LWC, cloud frequency, various meteorological measurements and information on nearby forest canopy were used to model cloud water deposition to gauge trends in deposition. Total deposition was calculated as the sum of cloud, dry and wet deposition estimates. Concentrations and deposition fluxes declined over the study period. The decreases in cloud water SO42＂ and NO3 concentrations were 40 percent and 26 percent, respectively. Three-year mean 5042 and NO3 deposition rates decreased by 71 percent and 70 percent, respectively. Trends in concentrations and depositions were comparable with trends in SO2 and NOx emissions from Tennessee Valley Authority power plants and aggregated emission reductions from electric generating units in adjacent states. Back trajectories were simulated with the HYSPLIT model and aggregated over cloud sampling periods from 2000 through 2007 and 2009 through 2011. Trajectories during periods with high H＋ concentrations traveled over local EGU （Electric Generating Unit） emission sources in Tennessee and Kentucky to the Ohio River Valley, Alabama and Georgia with the conclusion that these source regions contributed to acidic cloud water deposition at Clingmans Dome. This work was supported by U.S. Environmental Protection Agency and the Tennessee Valley Authority with infrastructure support provided by the National Park Service.

Massive Molecular Parallel Evolution of the HSP90AA1 Gene between High-elevation Anurans

HSP90 AA1 is part of the heat shock protein 90 gene family and has important functions against heat stress. We report a case of molecular level parallel evolution of the HSP90 AA1 gene in high elevation amphibians. HSP90 AA1 gene sequences of four high-elevation anurans, Bufo gargarizans, Nanorana parkeri, Rana kukunoris, and Scutiger boulengeri, were compared along with five of their low-elevation relatives. A total of 16 amino-acid sites were identified as parallel evolution between N. parkeri and R. kukunoris. We generated both model based（Zhang and Kumar＇s test） and empirical data based（parallel/divergence plotting） null distributions for non-parallel evolution, and both methods clearly determined that the observed number of parallel substitutions were significantly more than the null expectation. Furthermore, on the HSP90 AA1 gene tree, N. parkeri and R. kukunoris formed a strongly supported clade that was away from their respective relatives. This study provides a clear case of molecular parallel evolution, which may have significant implications in understanding the genetic mechanisms of high-elevation adaptation.

A new die-cast magnesium alloy for applications at higher elevated temperatures of 200-300℃

The development of lightweight magnesium(Mg)alloys capable of operating at elevated temperatures of 200-300℃and the ability of using high pressure die casting for high-volume manufacturing are the most advanced developments in manufacturing critical parts for internal combustion engines used in power tools.Here we report the microstructure and mechanical properties of a newly developed die-cast Mg-RE(La,Ce,Nd,Gd)-Al alloy capable of working at higher elevated temperatures of 200-300℃.The new alloy delivers the yield strength of 94 MPa at 300℃,which demonstrates a 42%increase over the benchmark AE44 high temperature die-cast Mg alloy.The new alloy also has good stiffness at elevated temperatures with its modulus only decreasing linearly by 13%from room temperature up to 300℃.Thermal analysis shows a minor peak at 364.7℃in the specific heat curve of the new alloy,indicating a good phase stability of the alloy up to 300℃.Nd and Gd have more affinity to Al for the formation of the minority of divorced Al-RE(Nd,Gd)based compounds,and the stable Al-poor Mg_(12)RE(La_(0.22)Ce_(0.13)Nd_(0.31)Gd_(0.31))Zn_(0.39)Al_(0.13)compound acts as the continuous inter-dendritic network,which contribute to the high mechanical performance and stability of the new die-cast Mg alloy at 200-300℃.

Shrinkage Behavior of High Performance Concrete at Different Elevated Temperatures under Different Sealing Conditions

The shrinkage behavior of high performance cement concrete made from Portland cement, ultra fine granulated blast furnace slag and pulverized fly ash with addition of superplasticizer at different temperatures from ambient temperature to 120 ℃ under different seuliug conditions was investigated by means of length change measurement on cylindrical concrete specimens along with curing age. Results show that drying shrinkage deformations of titled concrete specimens increased rapidly as the curing temperature rose. The development of dryiing shrinkage deformatian can be efficiently controlled with the aid of aluminum tape sealing as compared with the unsealed specimens, especially when the curing temperature is below 60℃ , although it will increase dramatically when the curing temperature is elevated to above 90%＂ . Polymer coating on concrete specimens showed a similar effect on the control of drying shrinkage as the sealing operation with aluminum tape.

Influence of dynamic tissue properties on temperature elevation and lesions during HIFU scanning therapy:Numerical simulation

When large tumors are treated,ablation of the entire volume of tumors requires multiple treatment spots formed by high intensity-focused ultrasound(HIFU)scanning therapy.The heating effect of HIFU on biological tissue is mainly reflected in temperature elevation and tissue lesions.Tissue property parameters vary with temperature and,in turn,the distribution of temperature as well as the heating effects change accordingly.In this study,an HIFU scanning therapy model considering dynamic tissue properties is provided.The acoustic fields and temperature fields are solved combining the Helmholtz wave equation with Pennes bio-heat transfer equation based on the finite element method(FEM)to investigate the effects of various tissue properties(i.e.,the attenuation coefficient,acoustic velocity,thermal conductivity,specific heat capacity,density,and blood perfusion rate)on heating performance.Comparisons of the temperature distribution and thermal lesions under static and dynamic properties are made based on the data of tissue property parameters varying with temperature.The results show that the dynamic changes of thermal conductivity,specific heat capacity,and acoustic velocity may account for the decrease of temperature elevation in HIFU treatment,while the dynamic changes of attenuation coefficient,density,and blood perfusion rate aggravate the increase of temperature on treatment spots.Compared with other properties,the dynamic change of attenuation coefficient has a greater impact on tissue temperature elevation.During HIFU scanning therapy,the temperature elevation and tissue lesions of the first treatment spot are smaller than those of the subsequent treatment spots,but the temperature on the last treatment spot drops faster during the cooling period.The ellipsoidal tissue lesion is not symmetrical;specifically,the part facing toward the previous treatment spot tends to be larger.Under the condition of the same doses,the temperature elevation and the size of tissue lesions under dynamic properties present significant growth in comparison to static properties.Besides,the tissue lesion begins to form earlier with a more unsymmetrical shape and is connected to the tissue lesion around the previous treatment spot.As a result,lesions around all the treatment spots are connected with each other to form a closed lesion region.The findings in this study reveal the influence of dynamic tissue properties on temperature elevation and lesions during HIFU scanning therapy,providing useful support for the optimization of treatment programs to guarantee higher efficacy and safety.

Reproduction and genetic diversity of Juniperus squamata along an elevational gradient in the Hengduan Mountains

Elevation plays a crucial factor in the distribution of plants,as environmental conditions become increasingly harsh at higher elevations.Previous studies have mainly focused on the effects of large-scale elevational gradients on plants,with little attention on the impact of smaller-scale gradients.In this study we used 14 microsatellite loci to survey the genetic structure of 332 Juniperus squamata plants along elevation gradient from two sites in the Hengduan Mountains.We found that the genetic structure(single,clonal,mosaic)of J.squamata shrubs is affected by differences in elevational gradients of only 150 m.Shrubs in the mid-elevation plots rarely have a clonal or mosaic structure compared to shrubs in lower-or higher-elevation plots.Human activity can significantly affect genetic structure,as well as reproductive strategy and genetic diversity.Sub-populations at mid-elevations had the highest yield of seed cones,lower levels of asexual reproduction and higher levels of genetic diversity.This may be due to the trade-off between elevational stress and anthropogenic disturbance at mid-elevation since there is greater elevational stress at higher-elevations and greater intensity of anthropogenic disturbance at lower-elevations.Our findings provide new insights into the finer scale genetic structure of alpine shrubs,which may improve the conservation and management of shrublands,a major vegetation type on the Hengduan Mountains and the Qinghai-Tibet Plateau.

Analysis and control of vibration of ropes in a high-rise elevator under earthquake excitation

In this research, the vibration of elevator ropes, including the main rope and compensation rope are investigated simultaneously in a high-rise elevator system under earthquake excitation. Moreover, the paper presents a new control method to restrain the sway of both ropes. This study considers varying rope lengths during elevator operation which cause other system parameters such as natural frequency, and damping ratio to be time-variant variables. The dynamics of the ropes are analyzed by solving the governing non-stationary, nonlinear equation numerically. In order to mitigate the vibration of ropes in several motion conditions, particularly upwards movement, downward movement, stopped at the lowest position, and stopped at the highest position, an active equipment is installed at the compensation sheave. The stability of the system using the controller is analyzed at four states: without disturbance and static car, without disturbance and mobile car, including disturbance and static car, and including disturbance and mobile car. The efficiency of the controller used for dampening the vibration of elevator ropes is validated by numerical simulation results.

Mechanism of Mg2+ dissolution from olivine and serpentine: Implication for bioleaching of high-magnesium nickel sulfide ore at elevated pH

To inhibit the dissolution of Mg^2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bioleaching factors on the dissolution of Mg^2+ from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg^2+ from olivine and serpentine was temperature, followed by p H and particle size. A novel method of bioleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg^2+ and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.

Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

In this study, the suitability of current design methods for the 0.2% proof yield strength of the comer regions for high strength cold-formed steel at normal room temperature was investigated. The current standard predictions are generally accurate for outer comer specimen but conservative for inner comer specimen. Based on the experimental results, an analytical model to predict the comer strength of high strength cold-formed steel at normal room temperature was also proposed. The comparison indicated that the proposed model predicted well the comer strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures. It is shown that the predictions obtained from the proposed model agree well with the test results. Generally the comer strength enhancement of high strength cold-formed steel decreases when the temperature increases.

Optical-Elevation Data Co-Registration and Classification-Based Height Normalization for Building Detection in Stereo VHR Images

Building detection in very high resolution (VHR) images is crucial for mapping and analysing urban environments. Since buildings are elevated objects, elevation data need to be integrated with images for reliable detection. This process requires two critical steps: optical-elevation data co-registration and aboveground elevation calculation. These two steps are still challenging to some extent. Therefore, this paper introduces optical-elevation data co-registration and normalization techniques for generating a dataset that facilitates elevation-based building detection. For achieving accurate co-registration, a dense set of stereo-based elevations is generated and co-registered to their relevant image based on their corresponding image locations. To normalize these co-registered elevations, the bare-earth elevations are detected based on classification information of some terrain-level features after achieving the image co-registration. The developed method was executed and validated. After implementation, 80% overall-quality of detection result was achieved with 94% correct detection. Together, the developed techniques successfully facilitate the incorporation of stereo-based elevations for detecting buildings in VHR remote sensing images.

HYDRAULIC ACTIVE GUIDE ROLLER SYSTEM FOR HIGH-SPEED ELEVATOR BASED ON FUZZY CONTROLLER

Increase of elevator speed brings about amplified vibrations of high-speed elevator. In order to reduce the horizontal vibrations of high-speed elevator, a new type of hydraulic active guide roller system based on fuzzy logic controller is developed. First the working principle of the hydraulic guide system is introduced, then the dynamic model of the horizontal vibrations for elevator cage with active guide roller system and the mathematical model of the hydraulic system are given. A fuzzy logic controller for the hydraulic system is designed to control the hydraulic actuator. To improve the control performance, preview compensation for the controller is provided. Finally, simulation and experiments are executed to verify the hydraulic active guide roller system and the control strategy. Both the simulation and experimental results indicate that the hydraulic active guide roller system can reduce the horizontal vibrations of the elevator effectively and has better effects than the passive one, and the fuzzy logic controller with preview compensation can give superior control performance.

Simulation on spread of fire smoke in the elevator shaft for a high-rise building

Spread of fire smoke in the elevator shaft of a high-rise building is influ- enced by many driving facts. We simulate smoke spreading in the elevator shaft, stair room, and pre-chamber with and without different supplied pressurized air. The simulation shows that smoke moves very fast in the elevator shaft. When a 12 floor high-rise building is in fire, smoke can fill up the elevator shaft in less than 1.5 min after a fire started, temperature in the elevator shaft can be higher than 187℃ in 5 rain, and the concentration of CO can also reach a high level. The elevator shaft has a very low visibility in less than about 100 s.

深度学习的大高差高海拔地区高程拟合方法

大高差高海拔地区的地形复杂多变,传统的高程拟合方法,如多项式拟合、曲面拟合、BP神经网络和遗传算法改进的神经网络等方法,拟合精度都有待提高。本文构建了一种基于深度学习的高程拟合方法,利用西部某铁路控制网的2020年一期二等水准测量数据,采用多层感知器(MLP)作为核心模型,通过结合RAdam优化器和GELU激活函数进行优化,该方法能够有效捕捉该地区的地形特征和高程变化规律,实现高精度的高程拟合。研究分析了不同优化器和激活函数组合对模型性能的影响,结果表明,深度学习模型在大高差高海拔地区高程拟合中表现出较佳性能,其均方误差(MSE)最低,平均绝对误差(MAE)最小,决定系数R 2最接近1,显著优于BP神经网络和遗传算法改进的神经网络方法。特别是RAdam优化器和GELU激活函数的组合,在模型性能上表现最佳。本文所构建出的深度学习大高差高程拟合方法,不仅精度较高且具有良好的泛化能力,能够适应大高差高海拔地区复杂多变的地形特征。

4 m/s超高速电梯系统的主参数配置与计算

随着城市建筑高层化进程的加速,带动了超高速电梯的迅速发展。针对国内超高速电梯研发滞后的现状,以4 m/s超高速电梯为设计对象,合理选择电梯驱动主机,配置电梯主要参数,对电梯系统的主机功率、速度、主轴负荷、曳引条件、钢丝绳安全系数、导轨强度等关键参数进行计算分析。结果表明,4 m/s超高速电梯主要参数配置合理,满足设计要求,为国内超高速电梯研究提供了理论计算参考依据。

巴中市80例急性ST段抬高型心肌梗死患者发生心力衰竭的危险因素分析

目的 分析巴中市急性ST段抬高型心肌梗死(STEMI)患者发生心力衰竭(HF)的现状及其影响因素。方法 选取2021年1月1日—2023年4月30日巴中市中心医院80例STEMI患者,根据有无发生HF分组,探寻可能导致STEMI患者HF的危险因素。结果 入组患者中28例发生HF,发生率35.00%。有HF组血清降钙素原(PCT)、总胆红素(TBiL)、超敏C反应蛋白(hs-CRP)、血小板平均体积(MPV)、同型半胱氨酸(Hcy)表达均较无HF组高(t=13.176、10.485、32.544、10.113、4.254,P<0.05);组间其他资料比较无统计学差异(P>0.05);Logistic回归分析显示血清PCT、TBiL、hs-CRP、MPV、Hcy高表达是导致STEMI患者发生HF的危险因素(OR>1,P<0.05)。结论 STEMI患者发生HF与血清PCT、TBiL、hs-CRP、MPV、Hcy指标高表达相关。

血清SCUBE1、Lp-PLA2水平与急性STEMI患者冠状动脉高血栓负荷的关系

目的探讨血清可溶性信号肽-CUB-表皮生长因子样结构域蛋白1(SCUBE1)、脂蛋白磷脂酶A2(Lp-PLA2)与急性ST段抬高型心肌梗死(STEMI)患者冠状动脉高血栓负荷(HTB)的关系。方法选取126例急性STEMI患者(急性STEMI组),根据血栓分级分为HTB患者57例和非HTB患者69例;另选取87名健康体检者为对照组。用酶联免疫吸附法检测血清SCUBE1、Lp-PLA2;用多因素Logistic回归分析急性STEMI患者冠状动脉HTB的影响因素;用受试者工作特征(ROC)曲线评估血清SCUBE1、Lp-PLA2水平对急性STEMI患者冠状动脉HTB的预测价值。结果急性STEMI组血清SCUBE1、Lp-PLA2水平高于对照组(P均<0.05)。HTB患者年龄、吸烟比例、低密度脂蛋白胆固醇、白细胞计数、SCUBE1、Lp-PLA2水平高于非HTB患者(P均<0.05),两者性别、基础疾病、罪犯血管、Gensini评分、左室射血分数比较差异无统计学意义(P均>0.05)。多因素Logistic回归分析显示,年龄增加、吸烟和血清SCUBE1、Lp-PLA2水平升高为急性STEMI患者冠状动脉HTB的独立危险因素(P均<0.05)。ROC曲线分析显示,血清SCUBE1、Lp-PLA2水平联合预测急性STEMI患者冠状动脉HTB的曲线下面积为0.874,大于二者单独预测的0.794、0.791(P均<0.05)。结论急性STEMI患者血清SCUBE1、Lp-PLA2水平升高与冠状动脉HTB密切相关,二者联合检测对急性STEMI患者冠状动脉HTB的预测价值较高。

三种冠状动脉内灌注用药方案对高血栓负荷急性ST段抬高型心肌梗死患者经皮冠状动脉介入术后心肌灌注及短期预后的影响

目的探讨三种冠状动脉内灌注用药方案对高血栓负荷急性ST段抬高型心肌梗死(STEMI)患者经皮冠状动脉介入(PCI)术后心肌灌注及短期预后的影响。方法前瞻性、单中心、随机对照研究。纳入2017年3月至2021年8月焦作市人民医院心内科高血栓负荷STEMI患者150例,按照分层区组随机化原则等分为三组各50例。A组:尼可地尔+替罗非班靶血管灌注;B组:尿激酶原+替罗非班靶血管灌注;C组:尼可地尔+尿激酶原+替罗非班靶血管灌注。于PCI术前、术后即刻检测记录梗死相关动脉(IRA)的心肌梗死溶栓试验(TIMI)血流分级、TIMI心肌灌注分级(TMPG)、校正的TIMI血流帧数(CTFC);于PCI术前、术后24 h记录心电图的ST段回落幅度;记录IRA开通后24 h内Curtis-Walker评分及恶性心律失常例数;于PCI术前、术后0 h、12 h、24 h、3 d及7 d检测血清高敏肌钙蛋白I(hs-cTnI);于PCI术前、术后24 h及7 d检测丙二醛(MDA)、超氧化物歧化酶(SOD);于PCI术前、术后7 d、术后1个月、术后6个月及术后12个月检测左心室射血分数(LVEF)。随访记录患者住院期间及出院后30 d内的出血事件及术后12个月内主要不良心血管事件(MACE)。结果(1)PCI术后即刻,C组患者的TIMI血流分级、TMPG均优于A组(Z=-16.610,P=0.023;Z=-18.400,P=0.015)和B组(Z=-15.130,P=0.046;Z=16.550,P=0.035);C组患者的CTFC帧数低于A组(P<0.001)和B组(P=0.001)。(2)PCI术后,C组患者的血清hs-cTnI水平低于A组和B组(均为P<0.001)。(3)PCI术后,C组患者的MDA水平低于A组和B组(均为P<0.001),SOD水平高于A组(P=0.004)和B组(P=0.024)。(4)PCI术后24 h,C组患者的ST段回落幅度大于A组(P=0.003)和B组(P=0.012),Curtis-Walker评分及恶性心律失常发生率低于A组(P=0.008、0.015)和B组(P=0.014、0.034)。(5)PCI术后,C组患者的LVEF水平高于A组和B组(均为P<0.001)。(6)住院期间及出院后30 d内,三组患者均未发生大出血,少量出血和微量出血的发生率比较无统计学差异(χ^(2)=1.385,P=0.500);术后12个月内,C组患者的MACE发生率低于A组和B组(χ^(2)=7.400,P=0.025)。结论尼可地尔+尿激酶原+替罗非班靶血管灌注具有协同作用,可有效改善STEMI患者PCI术后的心肌灌注,减轻术后心肌损伤和氧化应激损伤,促进ST段回落,降低恶性心律失常发生率,有效促进心功能恢复,减少心血管不良事件,且不增加术后出血。