Hydrodynamic characteristics and particle tracking of 90° lateral intakes at an inclined river slope

Lateral intakes are common in rivers.The pump effciency and sediment deposition are determined by the local hydrodynamic characteristics and mainstream division width.The hydraulic characteristics of lateral withdrawal from inclined river slopes at different intake elevations should be investigated.Meanwhile,the division width exhibits significant vertical non-uniformity at an inclined river slope,which should be clarified.Hence,a three-dimensional(3-D)hydrodynamic and particle-tracking model was developed with the Open Source Field Operation and Manipulation(Open FOAM),and the model was validated with physical model tests for 90°lateral withdrawal from an inclined side bank.The flow fields,withdrawal sources,and division widths were investigated with different intake bottom elevations,withdrawal discharges,and main channel velocities.This study showed that under inclined side bank conditions,water entered the intake at an oblique angle,causing significant 3-D spiral flows in the intake rather than two-dimensional closed recirculation.A lower withdrawal discharge,a lower bottom elevation of the intake,or a higher main channel velocity could further strengthen this phenomenon.The average division width and turbulent kinetic energy were smaller under inclined side bank conditions than under vertical bank conditions.With a low intake bottom elevation,a low withdrawal discharge,or a high main channel velocity,the sources of lateral withdrawal were in similar ranges near the local inclined bank in the vertical direction.Under inclined slope conditions,sediment deposition near the intake entrance could be reduced,compared to that under vertical slope conditions.The results provide hydrodynamic and sediment references for engineering designs for natural rivers with inclined terrains.

Deformation Characteristics of Hydrate-Bearing Sediments

The safe and efficient development of natural gas hydrate requires a deep understanding of the deformation behaviors of reservoirs.In this study,a series of triaxial shearing tests are carried out to investigate the deformation properties of hydrate-bearing sediments.Variations of volumetric and lateral strains versus hydrate saturation are analyzed comprehensively.Results indicate that the sediments with high hydrate saturation show dilative behaviors,which lead to strain-softening characteristics during shearing.The volumetric strain curves have a tendency to transform gradually from dilatation to compression with the increase in effective confining pressure.An easy prediction model is proposed to describe the relationship between volumetric and axial strains.The model coefficientβis the key dominating factor for the shape of volumetric strain curves and can be determined by the hydrate saturation and stress state.Moreover,a modified model is established for the calculation of lateral strain.The corresponding determination method is provided for the easy estimation of model coefficients for medium sand sediments containing hydrate.This study provides a theoretical and experimental reference for deformation estimation in natural gas hydrate development.

The change characteristics of the calculated wind wave fields near lateral boundaries with SWAN model

Since the wind wave model Simulating Waves Nearshore （SWAN） cannot effectively simulate the wave fields near the lateral boundaries, the change characteristics and the distortion ranges of calculated wave factors including wave heights, periods, directions, and lengths near the lateral boundaries of calculation domain are carefully studied in the case of different water depths and wind speeds respectively. The calculation results show that the effects of the variety of water depth and wind speed on the modeled different wave factors near the lateral boundaries are different. In the case of a certain wind speed, the greater the water depth is, the greater the distortion range is. In the case of a certain water depth, the distortion ranges defined by the relative errors of wave heights, periods, and lengths are different from those defined by the absolute errors of the corresponding wave factors. Moreover, the distortion ranges defined by the relative errors decrease with the increase of wind speed; whereas the distortion ranges defined by the absolute errors change a little with the variety of wind speed. The distortion range of wave direction decreases with the increase of wind speed. The calculated wave factors near the lateral boundaries with the SWAN model in the actual physical areas, such as Lake Taihu and Lake Dianshan considered in this study, are indeed distorted if the calculation domains are not enlarged on the basis of actual physical areas. Therefore, when SWAN is employed to calculate the wind wave fields near the shorelines of sea or inland lakes, the appropriate approaches must be adopted to reduce the calculation errors.

Lateral stress-induced propagation characteristics in photonic crystal fibres

Using the finite element method, this paper investigates lateral stress-induced propagation characteristics in a photonic crystal fibre of hexagonal symmetry. The results of simulation show the strong stress dependence of effective index of the fundamental guided mode, phase modal birefringence and confinement loss. It also finds that the contribution of the geometrical effect that is related only to deformation of the photonic crystal fibre and the stress-related contribution to phase modal birefringence and confinement loss are entirely different. Furthermore, polarization-dependent stress sensitivity of confinement loss is proposed in this paper.

Types and Characteristics of Chinese Gardens in the Later Mature Period

The development and evolution of Chinese gardens in the later mature period(the Qianlong-Xuantong period of the Qing Dynasty)were studied,and the types of gardens in this period were sorted out.Moreover,the characteristics of each type of representative gardens were analyzed,and the historical background,overall layout and gardening skills of various types of gardens in China in the period were summarized.Finally,the general characteristics of Chinese gardens in the later mature period were summarized.

An Improved Description of Characteristics Length in Substrate Current Model for Submicron and Deep-Submicron LDD MOSFET's

A novel substrate current model is proposed for submicron and deep-submicron li ghtly-doped-drain (LDD) n-MOSFET,with the emphasis on accurate description of the characteristics length by taking the effects of channel length and bias int o account.This is due to that the characteristics lenth significantly affects th e maximum lateral electric field and the length of velocity saturation region,bo th of which are very important in modeling the drain current and the substrate c urrent.The comparison between simulations and experiments shows a good predictio n of the model for submicron and deep-submicron LDD MOSFET.Moreover,the analyti cal model is suitable for descgn of devices as it is low in computation consumpt ion.

Experimental Study on Hydrodynamic Characteristics of Vertical-Axis Floating Tidal Current Energy Power Generation Device

To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device （VAFTCEPGD）, a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.

Plant Hormone Resistance and Agronomic Characteristics of the MT10 Mutant in Rice

The MT10 mutant plants had resistances to auxin.Under light and dark culture,the roots of MT10 seedlings had shown less lateral roots and short lateral roots.In soil,MT10 seedlings had shown not only no changed agronomic characteristics but also no significant difference with WT.

A dual-gate and dielectric-inserted lateral trench insulated gate bipolar transistor on a silicon-on-insulator substrate

In this paper, a novel dual-gate and dielectric-inserted lateral trench insulated gate bipolar transistor （DGDI LTIGBT） structure, which features a double extended trench gate and a dielectric inserted in the drift region, is proposed and discussed. The device can not only decrease the specific on-resistance Ron,sp , but also simultaneously improve the temperature performance. Simulation results show that the proposed LTIGBT achieves an ultra-low on-state voltage drop of 1.31 V at 700 A·cm-2 with a small half-cell pitch of 10.5 μm, a specific on-resistance R on,sp of 187 mΩ·mm2, and a high breakdown voltage of 250 V. The on-state voltage drop of the DGDI LTIGBT is 18% less than that of the DI LTIGBT and 30.3% less than that of the conventional LTIGBT. The proposed LTIGBT exhibits a good positive temperature coefficient for safety paralleling to handling larger currents and enhances the short-circuit capability while maintaining a low self-heating effect. Furthermore, it also shows a better tradeoff between the specific on-resistance and the turnoff loss, although it has a longer turnoff delay time.

弱起伏介质中lateral脉冲波的时间统计特性

在耗散弱起伏随机介质中,脉冲偶极子激发的脉冲波主要是以 lateral 波模传播的。本文从谱强度出发,运用 Yeh 等人的矩理论,对弱起伏随机介质中 lateral 脉冲波的时间统计特性作了细致的研究,得到了谱域中脉冲时间矩的计算公式,首次获得了lateral 脉冲波在丛林通信中的平均脉冲能量,平均到达时间及均方脉冲宽度的理论计算公式,并给出了数值计算结果。

188例侧向发育型肿瘤内镜及临床病理学分析

目的总结并评价结直肠侧向发育型肿瘤(laterally spreading tumor,LST)的内镜及临床病理特征。方法回顾性分析2010年12月至2019年12月首都医科大学附属北京世纪坛医院消化内科经内镜下治疗并诊断为LST的患者,根据LST病变内镜下特点,分为颗粒型LST(granular LST,LST-G)及非颗粒型LST(non-granular LST,LST-NG)两个亚组和四个亚型,总结并分析患者的临床一般资料、内镜下特征、组织病理特征、治疗方法等相关资料。结果(1)内镜下特征:共收集176例LST患者(188处病变),LST-NG亚组病变最多,LST病变直径为(22.48±12.26)mm(10~65 mm),LST-G组病变直径大于LST-NG组(P<0.001);LST-G及LST-NG好发于升结肠,LST-G较LST-NG更好发于直肠(χ^(2)=42.360,P<0.001);NICE分类对非肿瘤性息肉及癌和癌前病变诊断的敏感性为97.9%,特异性为82.6%,Kappa值为0.820(P<0.001),NICE分型与病理金标准具有很高的一致性。(2)病理特征:LST亚组均以管状腺瘤为主,LST-NG的癌变率包括HGIN为41.9%,高于LST-G的16.7%(χ^(2)=14.63,P<0.01);LST亚组间微卫星不稳定状态、p53的表达和Ki-67增殖指数差异均无统计学意义(P>0.05)。(3)治疗方式:结肠病变多选择使用EMR及ESD治疗,直肠病变多选择ESD及手术治疗(χ^(2)=19.596,P<0.01),<20 mm的病变多选用EMR治疗,20~<30 mm的病变多选用ESD治疗,≥30 mm的病变,手术治疗的比例逐渐升高(χ^(2)=102.725,P<0.01)。结论LST的临床特性及内镜下表现存在一定的特殊性,临床应重视识别LST病变,提高LST的检出,并对于不同病变采取合适的治疗方案。

BTA深孔加工镗杆的横向随机振动

采用随机方法分析了蕴含轴向流动流体的BTA(boring and trepanning association)深孔镗杆在随机力下的横向随机动力行为。建模时考察了流固耦合镗杆承受的弯曲、拉伸和扭转变形;经Galerkin Method离散化处理,分析了BTA镗杆在有、无随机激励两种情况的特征值和特征频率对振动特性的影响;利用响应方差最大值和谱密度解析了BTA镗杆横向振动的临界转速与临界失稳频率;明确了镗杆随转速、刚度、初始轴向总力和剪切模量等参数变化对系统振动特性的影响机制:镗杆转速变化对系统稳定性不再具有单调性,随BTA镗杆转速持续增加,系统可历经两次转速的临界失稳,相继出现二次失稳和二次稳定;增加系统等效刚度和等效剪切模量会促进工作过程的稳定,改变轴向力对工作过程稳定的影响不明显;并以随机振动物理试验信号的功率谱分析,验证了理论仿真结果与试验结果的一致性。该研究在一定程度上揭示了BTA深孔工艺系统运动状态的复杂性,这种研究模式为进一步分析在复杂状态下的运动演化提供了更多的可能。研究结论为更好地理解BTA深孔镗杆工作时的随机动力行为提供了依据,也为BTA深孔工艺过程的振动控制和参数优化奠定了理论基础。

老年发病的运动神经元病临床特点及诊治:15例病例系列分析

背景运动神经元病(motor neuron disease,MND)是一种神经系统变性疾病,预后不佳,多为中年起病,目前国内缺乏对老年起病的MND的研究。目的探讨60岁以上发病的MND的临床特点及预后。方法收集2008年9—2023年9月在解放军总医院第七医学中心住院的老年起病的MND患者的临床资料,分析其临床特征、诊治及结局。结果共收集15例老年起病的MND患者,男性10例,女5例,平均年龄(66.2±5.71)岁,发病年龄为60~79岁。延髓起病4例,单侧上肢起病6例,单侧下肢起病3例,双下肢起病1例,四肢起病1例。7例患者在起病18个月内出现了延髓症状,呼吸肌受累3例。临床分型方面,肌萎缩侧索硬化9例,进行性脊肌萎缩症4例,进行性延髓麻痹2例。6例在发病初期被误诊,误诊率达40%。5例放弃治疗,其余治疗效果也不佳。结论老年起病的MND男性多于女性,多为单侧起病,延髓起病的比例高,以肢体起病的患者更易、也更早出现延髓症状,呼吸肌受累比例较高。提示老年起病的MND可能生存期更短,共患病多,误诊率高,弃疗率高。

嵌岩桩水平承载力地基反力Matlock法分析

嵌岩桩在海上风电、跨海大桥等结构中的应用十分广泛,但在嵌岩桩水平承载特性方面的研究仍有较多不足。弹性地基反力法中的Matlock法在中国是用于计算水平承载桩承载力时应用最多的方法,但地基反力Matlock法针对嵌岩桩缺少合理的取值方法。基于现场试验数据建立并验证有限差分数值模型,通过数值模拟与参数分析,研究了岩体力学参数和桩基参数等因素对桩岩相互作用的影响,提出了Matlock法中地基反力系数比例系数的拟合计算公式。通过现场试验数据对提出的方法进行了验证,结果表明计算结果与实际情况较为相符,与其他方法比较,所提出的修正Matlock法相对非线性的p-y曲线法具有取值计算较为简便的优势。

基坑开挖对管桩竖向承载性状影响研究

针对基坑开挖引起管桩挤土效应的弱化,以及挤土效应弱化对管桩承载性质影响问题,开展了室内模型试验,并通过对模型试验进行数值建模,验证了数值模型的可靠性。在此基础上,从桩长、桩间距、桩侧摩阻力系数对开挖卸荷影响下管桩基础承载性状的影响展开研究。结果表明:开挖卸荷对管桩承载特性造成较大影响,极限承载力对应桩顶沉降量提高54.5%;数值计算发现,卸载前后极限荷载所对应最大沉降差率为9.52%,满足工程精度要求,验证了所提数值模型的可靠性;数值计算结果表明,随桩长提高,最大桩身轴力位置不断上升,而中性点位置却不断下降;桩间距越小,开挖卸荷对桩身轴力影响越大,而对负摩阻力影响越小;摩阻力系数为0.3时,摩阻力系数对桩身轴力及桩侧摩阻力发挥敏感度最高。

海上试桩不同桩型承载力特性研究

天津南港某高桩码头拟建场地有深厚密实砂层,通过试桩测定设计桩型对砂层的穿透及贯入能力,研究不同基桩承载力特性。试验结果表明:混凝土预制桩及钢管桩均有较好的穿透及贯入能力;基桩轴向极限承载力高应变检测结果小于静载试验,误差均在5%以内;混凝土预制桩桩端承载力占总承载力不小于44.6%,钢管桩桩端承载力占总承载力不小于21.9%;相同荷载作用下,混凝土预制方桩静载与动载沉降量之比为1.40,钢管桩为0.90,两者差异明显;基桩承载力达到极值时桩侧摩阻力要明显大于规范极限侧摩阻力,规范取值偏保守。

不同铵硝比对高山杜鹃侧枝生长和生理特性影响

为探究氮素形态对高山杜鹃侧枝生长的影响,以3年生盆栽高山杜鹃粉精灵为试验材料,单一氮源处理为对照,采用盆栽方式,研究5种不同氮素形态配比供应(铵硝比例分别为T1:100∶0,T2:75∶25,T3:50∶50,T4:25∶75和T5:0∶100)对其营养生长期侧枝生长、光合特性、代谢酶活性及营养元素积累的影响。结果表明,不同氮素形态下粉精灵不同生长期侧枝干物质积累量、苗高增量和侧枝长度均有所差异,以侧芽萌发期T3处理侧枝干物质积累量最高,T2处理在嫩侧枝期、侧枝半木质化期的苗高增量和侧枝长度均显著高于其他处理。侧枝半木质化期,与T1处理相比,T2处理显著提高净光合速率、蒸腾速率、气孔导度、水分利用率及磷含量,降低胞间二氧化碳浓度;叶片Fe元素吸收量以T1处理最高,Mg元素吸收量以T5处理最高。此外,在不同生长期,硝酸还原酶活性均随硝态氮含量的增加而增加,以嫩侧枝期酶活性最高。综上,不同氮素形态对高山杜鹃粉精灵侧枝生长和生理特性的影响有所差异,且混合氮源处理较单一氮源处理更有利于促进侧枝生长,以铵硝比例75∶25促进侧枝生长及提高养分积累和光合效能效果最好。本研究为筛选适合高山杜鹃生长发育的氮素施用方法提供了理论依据。

经跗骨窦入路内固定治疗跟骨骨折的解剖学特征及临床疗效

目的探讨经跗骨窦入路内固定治疗跟骨骨折的解剖学特征及临床疗效。方法对来源于成人尸体的20个足部标本进行解剖学测量得到安全手术范围,在此范围内采用经跗骨窦入路内固定治疗32例跟骨骨折患者。记录B9hler角、Gissane角、跟骨宽度、跟骨高度及并发症发生情况。采用踝关节MaryLand评分及AOFAS踝-后足评分评价临床疗效。结果(1)解剖学测量得到经跗骨窦入路内固定治疗跟骨骨折时避免腓肠神经损伤的安全手术范围:水平方向为11~28(16.90±4.93)mm,垂直方向为12~25(17.55±4.51)mm,对角方向为28~56(43.60±8.44)mm。(2)患者均获得随访,时间12~22个月。术后无切口感染、神经损伤、内固定失效等并发症发生。骨折均愈合,时间12~18周。B9hler角、Gissane角、跟骨宽度、跟骨高度:术后3、6个月均明显优于术前(P<0.01);术后6个月与术后3个月比较差异均无统计学意义(P>0.05)。踝关节MaryLand评分、AOFAS踝-后足评分:术后3、6、12个月均高于术后1个月(P<0.05);术后6、12个月均高于术后3个月(P<0.05);术后12个月与术后6个月比较差异均无统计学意义(P>0.05)。结论在安全手术范围内经跗骨窦入路内固定治疗跟骨骨折,可有效显露跟骨关节面,利于骨折复位及钢板固定,并能减少软组织及神经损伤等并发症的发生。

电泵浦有机发光二极管衬底侧向辐射研究

有机发光二极管衬底侧向辐射光谱与正向辐射光谱相比,存在明显的窄化现象。研究影响器件侧向辐射光谱窄化的因素,进一步减小辐射光谱的线宽,可为电泵浦有机发光二极管激光辐射研究打下基础。本文研究了随有机发光二极管空穴传输层NPB厚度的变化,器件衬底侧向辐射光谱的半高宽、峰位以及偏振特性的变化情况。比较了有机发光二极管衬底边缘两侧蒸镀银膜与未蒸镀银膜时的衬底侧向辐射光谱。研究发现蒸镀银膜时有机发光二极管的衬底侧向辐射光谱半高宽变窄,并且当空穴传输层NPB的厚度为130 nm时,器件衬底侧向辐射光谱半高宽低至14 nm。说明器件衬底两侧存在银膜作为反射镜的情况下,衬底中侧向传播的光将受到光学谐振腔的作用。本文的研究结果为有机发光二极管辐射光谱的窄化和辐射光放大提供了一种新思路。

外源激素对西瓜幼苗侧枝发育、膜脂过氧化反应及光合特性的影响

为探究植物激素对西瓜幼苗侧枝发育、膜脂过氧化反应和光合特性的影响,以黄小玉西瓜为试材,选择外源生长素[吲哚乙酸(IAA)]、细胞分裂素[6-苄氨基嘌呤(6-BA)]和脱落酸(ABA)3种激素,设置不同激素不同浓度喷施处理,定期测量西瓜幼苗株高、茎粗、侧枝长度、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、净光合速率、蒸腾速率、气孔导度和胞间CO_(2)浓度。结果表明,外源植物激素处理对西瓜侧枝发育、膜脂过氧化反应及光合特性的影响存在较大差异,低浓度的IAA处理能够抑制西瓜侧枝发育,并且可以促进植株生长,提高SOD和POD活性,降低MDA含量,提高净光合速率、气孔导度、胞间CO_(2)浓度和蒸腾速率;低浓度的6-BA能够促进西瓜幼苗侧枝发育,促进植株生长,提高SOD和POD活性,降低MDA含量,提高净光合速率和气孔导度;ABA能够抑制西瓜幼苗侧枝发育,抑制植株生长,超过一定浓度可降低SOD活性,增加MDA含量,降低胞间CO_(2)浓度。