Finite Element Analysis of Magnetohydrodynamic Mixed Convection in a Lid-Driven Trapezoidal Enclosure Having Heated Triangular Block

A numerical research on magnetohydrodynamic mixed convection flow in a lid-driven trapezoidal enclosure at non-uniform heating of bottom wall has been studied numerically. The enclosure consists of insulated top wall and cold side walls, too. It also contains a heated triangular block (Rot = 0° - 90°) located somewhere inside the enclosure. The boundary top wall of the enclosure is moving through uniform speed U0. The geometry of the model has been represented mathematically by coupled governing equations in accordance with proper boundary conditions and then a two-dimensional Galerkin finite element based numerical approach has been adopted to solve this paper. The numerical computations have been carried out for the wide range of parameters Prandtl number (0.5 ≤ Pr ≤ 2), Reynolds number (60 ≤ Re ≤ 120), Rayleigh number (Ra = 103) and Hartmann number (Ha = 20) taking with different rotations of heated triangular block. The results have been shown in the form of streamlines, temperature patterns or isotherms, average Nusselt number and average bulk temperature of the fluid in the enclosure at non-uniform heating of bottom wall. It is also indicated that both the streamlines, isotherm patterns strongly depend on the aforesaid governing parameters and location of the triangular block but the thermal conductivity of the triangular block has a noteworthy role on the isotherm pattern lines. Moreover, the variation of Nuav of hot bottom wall and θav in the enclosure is demonstrated here to show the characteristics of heat transfer in the enclosure.

Dominance-caused differences in transpiration of trees in a Karst broadleaved mixed forest

Estimating stand transpiration of natural forests using traditional methods through up-scaling of sap fl ux density from sample trees based on stand sapwood area only is diffi cult because of the complexity of species,ages,and hierarchical structure of natural forests.To improve stand transpiration estimation,we developed an up-scaling method by considering the tree dominance eff ect based on the assumption that individual tree transpiration is aff ected by crown dominance and species,in addition to factors previously considered such as meteorological conditions,sapwood area,and soil moisture.In this study,the meteorological factors,soil moisture,and sap fl ux density of 15 sample trees of diff erent species and dominance in a natural evergreen and deciduous broadleaved mixed forest were simultaneously monitored from March 2012 to February 2014 in the Karst mountain region in southwestern China.After establishing a single tree transpiration model which considers the eff ects of dominance and species,an up-scaling method was explored to estimate stand transpiration.The results show that the transpiration intensity increased exponentially with increasing tree dominance.The contribution to annual stand transpiration from a few dominant trees(5.4%of trees, 28.2% of basal area) was up to 65.0%. The correspondingcontribution was 16.2% from sub-dominant trees(7.6% of trees, 16.2% of basal area) and 22.8% from middleandlower-layer trees (87.0% of trees, 55.6% of basal area).The variation of individual tree transpiration was mainly(97.9%) explained by tree dominance, but very weakly bytree species. The estimated annual stand transpiration was300.2 mm when using the newly developed method whichconsiders tree dominance, 52.5 mm (14.9%) lower than theestimation (352.7 mm) of traditional method which considersonly the sapwood area eff ect, and 8.5 mm (2.7%) lowerthan the estimation (308.6 mm) which considers the eff ectsof both species composition and sapwood area. The maintree characteristics aff ecting stand transpiration are tree size(sapwood area) and dominance. Consideration of tree dominancewill signifi cantly improve stand transpiration estimationand provide a more solid basis for guiding integratedforest-water management at stand scale.

Modeling of Mixed Convection in a Lid Driven Wavy Enclosure with Two Square Blocks Placed at Different Positions

The purpose of this paper is to investigate the simulation of mixed convection in a lid-driven wavy enclosure with blocks positioned at various positions. This study also examined the impact of the longitudinal position of the heated block on heat transfer enhancement. The Galerkin weighted residual finite element method is employed to computationally solve the governing equations of Navier-Stokes, thermal energy, and mass conservation. The enclosure consists of two square heated blocks strategically placed at different heights—firstly, one set is closer to the bottom surface;secondly, one set is nearer to the middle area and finally, one set is closer to the upper undulating surface of the enclosure. The wavy top wall’s thermal insulation, along with active heating of the bottom wall and blocks, generates a dynamic convective atmosphere. In addition, the left wall ascends as the right wall falls, causing the flow formed by the lid. The study investigates the impact of the Richardson number on many factors, such as streamlines, isotherms, dimensionless temperature, velocity profiles, and average Nusselt numbers. These impacts are depicted through graphical illustrations. In all instances, two counter-rotating eddies were generated within the cage. Higher rotating speed consistently leads to improved performance, irrespective of other characteristics. Furthermore, an ideal amalgamation of the regulating factors would lead to increased heat transmission.

Hydrodynamic Mixed Convection in a Lid-Driven Hexagonal Cavity with Corner Heater

Hydrodynamic mixed convection in a lid-driven hexagonal cavity with corner heater is numerically simulated in this paper by employing finite element method. The working fluid is assigned as air with a Prandtl num-ber of 0.71 throughout the simulation. The left and right walls of the hex-agonal cavity are kept thermally insulated and the lid moves top to bottom at a constant speed U0. The top left and right walls of the enclosure are maintained at cold temperature Tc. The bottom right wall is considered with a corner heater whereas the bottom remaining part is adiabatic and inside the cavity a square shape heated block Th. The focus of the work is to investigate the effect of Hartmann number, Richardson number, Grashof number and Reynolds number on the fluid flow and heat transfer characteristics inside the enclosure. A set of graphical results is presented in terms of streamlines, isotherms, local Nusselt number, velocity profiles, temperature profiles and average Nusselt numbers. The results reveal that heat transfer rate increases with increasing Richardson number and Hartmann number. It is also observed that, Hartmann number is a good control parameter for heat transfer in fluid flow in hexagonal cavity.

Effect of Straw Mixing Amount on Mechanical Properties of Admixture-adding Hollow Block

The bonding mechanism between straw and concrete was analyzed through testing the compressive strength and flexural strength of hollow block, with different straw amount and different dosage and types of admixtures. The test results show that the mechanical properties of hollow blocks reduced after adding straws, and the more straws was added, the more hollow block density decreased. But adding A12（SO4）3 and CaC12 could improve the dense degree between rice straw and concrete. And when the proportion of straw mixing amount was 10%, the flexural strength of the early strength agent （2% A12（SO4）3, CaC12） added hollow block reached as maximal as 3.1 MPa, while the compressive strength was 9.1 MPa, consisting with the strength grade of common concrete hollow block MU7.5.

MIXED-GRAINED CMOS FIELD PROGRAMMABLE ANALOG ARRAY FOR SMART SENSORY APPLICATIONS

The drive towards shorter design cycles for analog integrated circuits has given impetus to the development of Field Programmable Analog Arrays(FPAAs),which are the analogue counterparts of Field Programmable Gate Arrays(FPGAs).In this paper,we present a new design methodology which using FPAA as a powerful analog front-end processing platform in the smart sensory microsystem.The proposed FPAA contains 16 homogeneous mixed-grained Configurable Analog Blocks(CABs) which house a variety of processing elements especially the proposed fine-grained Core Configurable Amplifiers(CCAs).The high flexible CABs allow the FPAA operating in both continuous-time and discrete-time approaches suitable to support variety of sensors.To reduce the nonideal parasitic effects and save area,the fat-tree interconnection network is adopted in this FPAA.The functionality of this FPAA is demonstrated through embedding of voltage and capacitive sensor signal readout circuits and a configurable band pass filter.The minimal detectable voltage and capacitor achieves 38 uV and 8.3 aF respectively within 100 Hz sensor bandwidth.The power consumption comparison of CCA in three applications shows that the FPAA has high power efficiency.And the simulation results also show that the FPAA has good tolerance with wide PVT variations.

反式Twin-block治疗替牙期安氏Ⅲ类错牙合疗效研究

目的评价应用反式Twin-block治疗替牙期安氏Ⅲ类错牙合的临床疗效。方法应用反式Twin-block矫治器治疗替牙期安氏Ⅲ类错牙合11例,并对治疗前后的头影测量结果进行分析。结果 11例替牙期安氏Ⅲ类错牙合患者侧貌改善,前牙覆牙合覆盖正常。结论反式Twin-block矫治器能有效治疗替牙期安氏Ⅲ类错牙合。

改良Twin-Block矫治器治疗安氏Ⅱ~2类错的临床观察

目的研究改良Twin-Block矫治器对生长发育期安氏Ⅱ类2分类错的矫治作用。方法选择27例替牙期或恒牙早期安氏Ⅱ类2分类错患者,应用改良Twin-Block矫治器进行矫治,通过测量治疗前后X线头颅定位侧位片,进行统计学分析。结果矫治后磨牙调整为中性关系或轻度近中关系;前牙覆覆盖正常;上下颌关系及软组织侧貌协调。结论改良Twin-Block矫治器治疗早期安氏Ⅱ类2分类错畸形疗效显著,能促进下颌生长,改善下颌后缩。

反向Twin-block矫治器治疗替牙期安氏Ⅲ类错[牙合]畸形的临床疗效观察

目的 探究反向Twin-block矫治器在替牙期安氏Ⅲ类错[牙合]畸形治疗中的临床矫治效能。方法 使用反向Twin-block矫治器治疗替牙期安氏Ⅲ类错[牙合]畸形患者10例,测量对比患者治疗前后的各项头影测量数值。结果 患者治疗后∠SNA增加(3.18±2.58)°,∠ANB增加(3.57±1.26)°,Wits值增加(3.66±2.72)mm,∠U1-SN增加(8.12±7.67)°,∠L1-MP减小(-2.91±4.00)°,变化均具有统计学意义。结论 反向Twinblock矫治器针对于替牙期安氏Ⅲ类错[牙合]畸形具有一定的疗效,可协调上下颌骨的位置关系,有效解除反[牙合]。

Stable oxygen-hydrogen isotopes reveal water use strategies of Tamarix taklamakanensis in the Taklimakan Desert, China

Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities.Consequently,T.taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources(deep soil water and groundwater),reflecting its adaptations to the different habitats in the arid desert environment.These findings improve our understanding on determining the water sources and water use strategies of T.taklamakanensis in the Taklimakan Desert.

Integrating potential distribution of dominant vegetation and land use into ecological restoration in the Yellow River Basin,China

Due to the influence of human activities such as cultivation and urban construction,the ecosystem of the Yellow River Basin(YRB)is subjected to increased vulnerability and even potential risk of destruction.Ecological restoration has led to an increase in vegetation,but excessive afforestation conversely results in low survival rate of trees,water shortages,and biodiversity loss.It is of great significance for achieving sustainable development of forests to reasonable revegetation in the region.At present,the potential distribution pattern of dominant species and their mixed forms in the basin has not been effectively studied.This study simulated the potential distribution of dominant vegetation in the YRB based on Maximum Entropy(Max Ent)and Genetic Algorithm for Rule-Set Prediction(GARP)and explored the impact of human interference on it by employing land use as the environmental filter to distinguish the regions of human activities.We further predicted the potential distribution of typically mixed forests and discussed their human interference.The main results are as follows:(1)Except for Caragana korshinskii,all models had good above performance(0.7<the mean AUC<1).Except for Caragana korshinskii,the area under the curve(AUC)for 90%of the models indicated that Max Ent performed better than GARP,and Max Ent easily lead to over-fitting while GARP predicted a wider range.(2)Except for Nitraria tangutorum,the dominant types of vegetation such as Pinus tabulaeformis,Platycladus orientalis,and Hippophae rhamnoides mainly distributed in southern Gansu,Shaanxi,and south-central Shanxi.Among them,the largest suitable area of Artemisia gmelinii and Stipa bungeana(High suitable area)were approximately 56.7×104 km2(38.8%)and 54.7×104 km2(28.5%)with the area occupied by large-scale cultivation being 17.5×104 km2(39.4%)and 18.9×104 km2(48%),respectively,which indicated human activities caused great damage to the core growth regions of these vegetation.(3)Mean temperature of coldest quarter or month mainly constrained the growth of most vegetation in the YRB in terms of temperature,while precipitation of wettest/driest month is one of the dominant factors.However,some vegetation responded differently to other meteorological factors due to niche differences.(4)Most of the mixed forests were distributed in southern Gansu,Shaanxi,and Shanxi provinces;its middle and high suitable areas were mainly concentrated in Shaanxi and southern and central Shanxi,where the cultivated land had occupied most of them.Therefore,the results showed that the restoration of herbaceous vegetation such as Artemisia gmelinii and Stipa bungeana has a high potential and it is appropriate that the measures for afforestation should be concentrated in the areas like the lower reaches of the Weihe,Jinghe,and Beiluo rivers and Luliang Mountain,where the cultivated land overlaps with the high suitable areas of the corresponding vegetation and the mixed forests with less water consumption and wide distribution,such as Caragana korshinskii-Hippophae rhamnoides,Pinus tabulaeformis-Quercus liaotungensis,and Ostryopsis davidiana-Stipa bungeana-Hippophae rhamnoides.The results of this study can provide effective guidance for mixed forest plantations and vegetation conservation in the YRB.

ARoad Segmentation Model Based on Mixture of the Convolutional Neural Network and the Transformer Network

Convolutional neural networks(CNN)based on U-shaped structures and skip connections play a pivotal role in various image segmentation tasks.Recently,Transformer starts to lead new trends in the image segmentation task.Transformer layer can construct the relationship between all pixels,and the two parties can complement each other well.On the basis of these characteristics,we try to combine Transformer pipeline and convolutional neural network pipeline to gain the advantages of both.The image is put into the U-shaped encoder-decoder architecture based on empirical combination of self-attention and convolution,in which skip connections are utilized for localglobal semantic feature learning.At the same time,the image is also put into the convolutional neural network architecture.The final segmentation result will be formed by Mix block which combines both.The mixture model of the convolutional neural network and the Transformer network for road segmentation(MCTNet)can achieve effective segmentation results on KITTI dataset and Unstructured Road Scene(URS)dataset built by ourselves.Codes,self-built datasets and trainable models will be available on https://github.com/xflxfl1992/MCTNet.

Variable Selection in Randomized Block Design Experiment

In the experimental field, researchers need very often to select the best subset model as well as reach the best model estimation simultaneously. Selecting the best subset of variables will improve the prediction accuracy as noninformative variables will be removed. Having a model with high prediction accuracy allows the researchers to use the model for future forecasting. In this paper, we investigate the differences between various variable selection methods. The aim is to compare the analysis of the frequentist methodology (the backward elimination), penalised shrinkage method (the Adaptive LASSO) and the Least Angle Regression (LARS) for selecting the active variables for data produced by the blocked design experiment. The result of the comparative study supports the utilization of the LARS method for statistical analysis of data from blocked experiments.

Twin-block矫治器引导下颌向前移动在替牙列期安氏Ⅱ类下颌后缩患者中的应用研究

目的探究Twin-block矫治器引导下颌向前移动在替牙列期安氏Ⅱ类下颌后缩患者中的应用效果。方法选取2021年3月~2022年6月本院收治的替牙列期安氏Ⅱ类下颌后缩患者84例,采用随机数表法分为2组,对照组(n=42)给予MBT直丝弓矫治器治疗,试验组(n=42)给予Twin-block矫治器引导下颌向前移动治疗,连续治疗12个月,比较治疗前后2组患者软组织指标、舌骨位置测量结果以及上气道变化情况。结果治疗后试验组软组织面角高于对照组,面突角、上下唇-审美平面距均低于对照组(P<0.05);治疗后试验组舌骨点至锥前平面距离(H-CVP)、舌骨点至腭平面距离(H-PP)、舌骨点至下颌平面距离(H-MP)、舌骨点至后鼻棘点距离(H-PNS)均高于对照组(P<0.05);治疗后试验组上气道总体积(V总)、腭咽体积(V腭咽)、舌咽体积(V舌咽)均高于对照组、鼻咽体积(V鼻咽)低于对照组(P<0.05)。结论Twin-block矫治器引导下颌向前移动对改善替牙列期安氏Ⅱ类下颌后缩患者面型、舌骨位置以及呼吸功能有积极意义。

Recoverability analysis of block-sparse representation

Recoverability of block-sparse signals by convex relaxation methods is considered for the underdetermined linear model. In previous works, some explicit but pessimistic recoverability results which were associated with the dictionary were presented. This paper shows the recoverability of block-sparse signals are associated with the block structure when a random dictionary is given. Several probability inequalities are obtained to show how the recoverability changes along with the block structure parameters, such as the number of nonzero blocks, the block length, the dimension of the measurements and the dimension of the block-sparse representation signal. Also, this paper concludes that if the block-sparse structure can be considered, the recoverability of the signals wil be improved. Numerical examples are given to il ustrate the availability of the presented theoretical results.

规划求解在优化混匀矿BLOCK配比中的应用

摘要主要阐述了利用Excel办公软件中的规划求解工具对模型计算混匀矿BLOCK配比，省去了繁琐的人工计算过程，提高了混匀矿BLOCK配比的准确性，有利于混匀矿质量的稳定。

平曲线上大调整量弹性支承块式轨道结构动力响应规律分析

基于车辆-轨道耦合动力学及有限元方法,采用ABAQUS®-MATLAB®联合仿真技术,建立车辆-钢轨-弹性支承块式无砟轨道耦合动力学模型,研究不同的车辆类型在多种平曲线线型条件下大调整量弹性支承块式无砟轨道的动力响应特性,分析并评估弹性支承块式无砟轨道用于小半径曲线线路条件的适用性和可行性。研究结果表明:轨下垫板高度的调整对各项指标的影响比支承块帽檐高度调整对各项指标的影响小,当调高从-60 mm增加到60 mm时,轨距扩大量增幅达到了235.00%,当且仅当在调低或调高轨下垫板高度时,轨距扩大量才会发生明显变化;随曲线半径减小,轨距扩大、行车安全性、稳定性等指标随之增大;小曲线半径对支承块的轨距保持能力具有较大影响,当半径减小到2 800 m时,轨距扩大量相比于半径5 000 m的增大了67.50%;与客车相比,当货车运行至小半径曲线路段时,轨距扩大量具有明显的增大趋势,在相同运行条件下,相比于客车的轨距扩大量,货车的轨距扩大量增幅达到110.45%。总体而言,在不同曲线半径、支承块调高情况下,列车运行各项安全性、稳定性及轨距扩大量等指标均在规范规定的安全限值以内,总体来看轨道几何保持能力良好;在实际工程中,当列车尤其是货车经过小曲线半径路段时,应尽量降低行驶速度,以避免困难路段所带来的影响行车安全性、稳定性等隐患。

布比卡因+亚甲蓝混合液肛周封闭联合中药熏蒸对混合痔嵌顿术后的效果观察

目的:探究布比卡因+亚甲蓝混合液肛周封闭术联合中药熏蒸对混合痔嵌顿术后的效果。方法:2022年8月—2023年8月选取于九江市第一人民医院行手术治疗的混合痔嵌顿患者80例,用随机抽签法分为对照组(行中药熏蒸治疗)与观察组(行布比卡因+亚甲蓝混合液肛周封闭联合中药熏蒸治疗),各40例。比较两组临床疗效、疼痛程度、肛门功能、术后并发症。结果:与对照组(75.00%)比较,观察组总有效率(92.50%)显著更高(P<0.05)。术后24 h及治疗14 d后,两组视觉模拟评分法评分均较术前显著降低,且观察组[(3.39±0.87)、(1.82±0.56)分]较对照组[(4.27±1.03)、(2.37±0.70)分]均显著更低(P<0.05)。术后1个月,两组肛管最大收缩压、肛管静息压均升高,肛管高压带均缩短,且与对照组[(112.36±10.87)mmHg、(51.11±4.25)mmHg、(2.94±0.36)cm]比较,观察组肛管最大收缩压[(119.48±11.31)mmHg]、肛管静息压[(54.56±4.39)mmHg]均显著更高,肛管高压带[(2.71±0.28)cm]显著更短(P<0.05)。与对照组(27.50%)比较,观察组术后并发症发生率(10.00%)显著更低(P<0.05)。结论:布比卡因+亚甲蓝混合液肛周封闭联合中药熏蒸可减轻混合痔嵌顿患者术后疼痛,改善肛门功能,降低术后并发症发生率,促进患者术后恢复。

基于MXI测度的街区功能混合类型及分布特征解析——以南京老城区为例

功能混合是城市集约发展和活力提升的关键因素,街区是功能混合的关键尺度层级,其混合测度有助于存量空间功能布局的认知和评估。选用功能混合指数(MXI)来测度南京老城街区单元的功能构成,通过测度结果的GIS地图映射和类型分析,呈现不同功能混合街区单元的空间分布,解析街区功能混合类型的分布与老城区位及空间结构的关联性,归纳街区混合类型的空间分布模式,并提示低混合度街区可能存在的问题。

东昆仑西段岩碧山构造混杂带构造变形特征及就位机制研究

岩碧山构造混杂岩带,位于南昆仑地块北侧,东与畅流沟—向阳泉蛇绿混杂岩相连,东南汇入木孜塔格—布青山蛇绿构造混杂岩带,近北西西向发育以逆冲及走滑性质构造系为主体,叠加了晚期逆冲推覆构造的混杂岩带(邵东等,2017)(图1)。根据岩碧山构造混杂岩带的物质特征,将其划分为早古生代岛弧型、变质基底、洋壳杂岩3类岩块,长英质糜棱岩、构造碎裂岩2类基质和晚古生代洋盆演化相关的洋壳杂岩组成。