Small-scale fire tests in the underwater tunnel section model with new sidewall smoke extraction

The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust holes.In order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were conducted.By changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were studied.On this basis,the optimal smoke control strategy was proposed for different fire scenarios.The research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels.

31.38 Gb/s GaN-based LED array visible light communication system enhanced with V-pit and sidewall quantum well structure

Although the 5G wireless network has made significant advances,it is not enough to accommodate the rapidly rising requirement for broader bandwidth in post-5G and 6G eras.As a result,emerging technologies in higher frequencies including visible light communication(VLC),are becoming a hot topic.In particular,LED-based VLC is foreseen as a key enabler for achieving data rates at the Tb/s level in indoor scenarios using multi-color LED arrays with wavelength division multiplexing(WDM)technology.This paper proposes an optimized multi-color LED array chip for high-speed VLC systems.Its long-wavelength GaN-based LED units are remarkably enhanced by V-pit structure in their efficiency,especially in the“yellow gap”region,and it achieves significant improvement in data rate compared with earlier research.This work investigates the V-pit structure and tries to provide insight by introducing a new equivalent circuit model,which provides an explanation of the simulation and experiment results.In the final test using a laboratory communication system,the data rates of eight channels from short to long wavelength are 3.91 Gb/s,3.77 Gb/s,3.67 Gb/s,4.40 Gb/s,3.78 Gb/s,3.18 Gb/s,4.31 Gb/s,and 4.35 Gb/s(31.38 Gb/s in total),with advanced digital signal processing(DSP)techniques including digital equalization technique and bit-power loading discrete multitone(DMT)modulation format.

Thermal stratification level of low sidewall air supply with air-conditioning system in large space

The thermal stratification level of low sidewall air supply system in large space was defined. Depending on the experiment of low sidewall air supply in summer 2008,the thermal stratification level was studied by simulation. Based on the simulation of experiment condition,the air velocity and vertical temperature distribution in a large space were simulated at different air-outlet velocities,and then the thermal stratification level line was obtained. The simulation results well match with the experimental ones and the average relative error is 3.4%. The thermal stratification level is heightened by increasing the air-outlet velocity with low sidewall air supply mode. It is concluded that when air-outlet velocity is 0.29 m/s,which is the experimental case,a uniform thermal environment in the higher occupied zone and a stable stratification level are formed. When the air-outlet velocity is low,such as 0.05 m/s,the thermal stratification level is too low and the air velocity is too small to meet the human thermal comfort in the occupied zone. So,it would be reasonable that the air-outlet velocity may be designed as 0.31 m/s if the height of the occupied zone is 2 m.

Effect of Organophilic Montmorillonite on Thermal-oxidative Aging Behavior of SBS Modified Bitumen Crack Filling Material

Styrene-butadiene-styrene （SBS） modified bitumen crack filling material with organophilic montmorillonite （OCFM） was prepared by melt blending. X-ray diffraction analysis shows that the interlayer spacing of organophilic montmorillonite （OMMT） in OCFM is widened and an exfoliated structure may be formed. Thermal-oxidative aging behavior of OCFM and SBS modified bitumen crack filling material （SCFM） was investigated. The experimental results indicate that the rate of thermal-oxidative aging of OCFM is much slower than that of SCFM, which can be attributed to barrier of exfoliated structure of OCFM to oxygen.

Research and application of sidewall stability predic-tion method based on analytic hierarchy process and fuzzy integrative evaluation method

As a difficult problem, sidewall instability has been beset drilling workers all the time. Not only does it cause huge economic losses, but also it determines the success or failure of drilling engineering. Due to complex relationship between various factors which influence sidewall stability, it hasn’t been found a widely applied method to predicate sidewall stability so far. Therefore, in order to formulate corresponding measures to ensure successful drilling, searching for a kind of better method to forecast sidewall stability before drilling becomes an imperative and significant topic for drilling engineering. On the basis of traditional sidewall stability analytical method, we have put forward the Fuzzy Comprehensive Evaluation Method to forecast sidewall stability regulation using physico-chemical performance parameters of the clay mineral. This method has been improved by introducing the Analytic Hierarchy Process (AHP) and the Maximum Subjection Principle in the application process. After introducing Analytic Hierarchy Process to identify weight, and Maximum Subjection Principle to obtain evaluation results, it has reduced the influence of human factors and enhanced the accuracy of the fuzzy evaluation results. The application in Hailaer Area indicates that this method can predict sidewall stability of gas-oil well with high credibility and strong practicability.

Numerical Simulation of PMM Tests for A Ship in Close Proximity to Sidewall and Maneuvering Stability Analysis

As the maneuverability of a ship navigating close to a bank is influenced by the sidewall, the assessment of ship maneuvering stability is important. The hydrodynamic derivatives measured by the planar motion mechanism （PMM） test provide a way to predict the change of ship maneuverability. This paper presents a numerical simulation of PMM model tests with variant distances to a vertical bank by using unsteady RANS equations. A hybrid dynamic mesh technique is developed to realize the mesh configuration and remeshing of dynamic PMM tests when the ship is close to the bank. The proposed method is validated by comparing numerical results with results of PMM tests in a circulating water channel. The first-order hydrodynamic derivatives of the ship are analyzed from the time history of lateral force and yaw moment according to the multiple-run simulating procedure and the variations of hydrodynamic derivatives with the ship-sidewall distance are given. The straight line stability and directional stability are also discussed and stable or unstable zone of proportional-derivative （PD） controller parameters for directional stability is shown, which can be a reference for course keeping operation when sailing near a bank.

A New Arrangement with Nonlinear Sidewalls for Tanker Ship Storage Panels

Sloshing phenomenon in a moving container is a complicated free surface flow problem. It has a wide range of engineering applications, especially in tanker ships and Liquefied Natural Gas (LNG) carriers. When the tank in these vehicles is partially filled, it is essential to be able to evaluate the fluid dynamic loads on tank perimeter. Different geometric shapes such as rectangular, cylindrical, elliptical, spherical and circular conical have been suggested for ship storage tanks by previous researchers. In this paper a numerical model is developed based on incompressible and inviscid fluid motion for the liquid sloshing phenomenon. The coupled BEM-FEM is used to solve the governing equations and nonlinear free surface boundary conditions. The results are validated for rectangular container using data obtained for a horizontal periodic sway motion. Using the results of this model a new arrangement of trapezoidal shapes with quadratic sidewalls is suggested for tanker ship storage panels. The suggested geometric shape not only has a maximum surrounded tank volume to the constant available volume, but also reduces the sloshing effects more efficiently than the existing geometric shapes.

Study on mechanical principle of reinforcing sidewalls and corners of roadway to control floor heave by anchors

The movement principle of sidewalls and floor of extraction opening is analyzed, it is found that floor heave not only has something to do with the floor strata, but sidewalls. The effect of sidewall anchor and corner anchor is studied, the mechanical principle of reinforcing sidewalls and corners is put forward and applied in engineering practice.

SIDEWALL FLOW STABILITY IN THE MHD CHANNEL FLOWS

The velocity distribution between two sidewalls is; M-shaped for the MHD channel flows with rectangular cross section and thin conducting walls in a strong transverse magnetic field. Assume that the dimensionless numbers R(m) much less than 1, M, N much greater than 1, and sigma* much less than 1 and that the distance between two perpendicular walls is very long in comparison with the distance between two sidewalls. First, the equation for steady flow is established, and the solution of M-shaped velocity distribution is given. Then, an equation for stability of small disturbances is derived based on the velocity distribution obtained. Finally, it is proved that the stability equation for sidewall how can be transformed into the famous Orr-Sommerfeld equation, in addition, the following theorems are also proved, namely, the analogy theorem, the generalized Rayleigh's theorem, the generalized Fjortoft's theorem and the generalized Joseph's theorems.

Experimental Investigation of Flame Structure and Combustion Limit During Premixed Methane/Air Jet Flame and Sidewall Interaction

The effects of inlet gas parameters and sloping sidewall angle on the flame structure and combustion limit with and without sidewall were experimentally investigated.Flame height and impact angle were obtained by chemiluminescence intensity analysis of CH*distribution.First,the combustion characteristics of flame with and without sidewall at different equivalence ratios were explored;then,the influence of Reynolds number and inlet gas temperature on flame structure and combustion limit of v-shaped flame with sidewall were analyzed,and the results with sidewall were compared with those without sidewall.Finally,the variation trend of flame parameters with different sloping sidewall angles was analyzed.The experimental results show that the existence of sidewall makes flame shape change from“M-shaped”to“inverted N-shaped”,and conical shape to trapezoidal shape.The inhibition effect of sidewall on flame stretching downstream is strengthened with the increase in Reynolds number;but as the temperature of the inlet gas increases,the inhibitory effect is obviously weakened.When sloping sidewall angle decreases from 90°to 55°at 5°intervals,flame height and impact angle of v-shaped flame reach the extreme value whenβ=80°.Compared with the case without sidewall,the range of v-shaped flame with sidewall has no obvious trend of broadening or shrinking when inlet gas temperature is increased;however,as sloping sidewall angle decreases,the range of the v-shaped flame shrinks obviously and flammability limit increases significantly.

基于电弧声信号的窄间隙脉冲熔化极气体保护焊侧壁熔合状态在线识别

为在焊接过程中实时了解焊缝内部的焊接状况,构建了电弧声信号实时采集系统。在焊枪摆动中心处于不同位置的情况下,进行了电弧声信号特征与侧壁熔合状态的相关性分析。分别从时域与频域中提取了与侧壁熔合状态相关性较强的电弧声特征。为进一步提高熔合状态预测的有效性,采用电弧声特征参量构建了支持向量回归的侧壁熔合状态识别模型。为减小不良特征对识别模型的影响,显著提高模型的识别精度,采用遗传算法进行了参数寻优。参数寻优后模型的总体识别率达93.33%,实现了窄间隙侧壁熔合状态的有效识别。

高应力扇形中深孔采场边帮控制爆破参数优化

针对扇形孔采场爆破边帮控制问题,提出了一种将靠近边帮的扇形炮孔施工成垂直平行孔用以控制边帮的构想。首先,通过理论计算得到4组平行炮孔不耦合系数与炮孔间距匹配下的模型参数,使用LS-DYNA对4组参数进行数值模拟;然后,通过对比分析4组模型在无地应力作用和不同方向地应力作用时的爆破裂纹扩展情况,获得最优参数;最后基于优化参数开展工业试验。结果表明:高地应力会促进最大应力方向爆破裂纹扩展;4种模型中,不耦合系数为1.65,炮孔间距为1.1 m时开挖区域破岩效果最为合理;在试验采场开展工业试验,使用优化后的爆破参数进行爆破,采场回采后边帮平整,稳定性较好,验证了研究结论的正确性。

渤海海域井壁取心裂解烃S_(2)烃类损失恢复回归分析

地化录井受工程、地质条件及人为因素的影响,往往造成岩石样品从井底到地表的烃类损失,不能很好地反映地下储层的真实含油气信息,因此需要一种合理准确的方法进行烃类损失恢复。针对渤海海域不同地区不同层位的岩屑值(自变量)与壁心值(因变量)之间的关系,基于最小二乘法、梯度下降法及其衍生算法,以多元线性回归和非线性回归两种方式来拟合研究区井壁取心数据。多元线性回归模型可使用标准方程法、岭回归、LASSO(Least Absolute Shrinkage and Selection Operator)及弹性网进行回归拟合,非线性回归模型可使用梯度下降法和分段函数的拟合方法。对不同回归分析方法进行分析对比可知,岭回归在计算线性关系的烃类损失方面具有较好的效果,决定系数r^(2)均超过0.7;基于岭回归分段函数拟合和非线性回归模型y=x/(b+kx)适合非线性烃类损失恢复。与传统的烃类损失恢复方法相比,使用量化的方式对研究区烃类进行恢复,更加科学全面,具有广泛的应用前景。

高侧壁垂直度超浅铌酸锂光栅耦合器的加工工艺及耦合效率

利用聚焦离子束(FIB)在铌酸锂(LN)表面形成100 nm及以下深度的超浅光栅耦合器结构。为了提高刻蚀侧壁垂直度、避免开口展宽效应对光栅形貌的影响,在LN表面覆盖非晶硅(α-Si)作为掩膜层,实际刻蚀深度为α-Si层厚度和LN表面目标刻蚀深度之和,且刻蚀过程中产生的开口效应仅存在于α-Si层。通过氢氧化钾(KOH)溶液选择性地去除α-Si层,留下的LN表面结构侧壁陡直且无开口展宽效应。制备了刻蚀深度108 nm的超浅光栅耦合器,在924 nm波长处,其耦合效率为23.3%。制备了刻蚀深度70 nm的超浅光栅耦合器,在935 nm波长处,其耦合效率为14.4%。该研究为LN光栅耦合器的发展与应用提供了有益指导。

高温小井眼大直径岩心旋转井壁取心仪研制及应用

随着油气勘探开发难度增大,特别是海洋油气勘探开发的不断加大,以及深水井、高温井越来越多,地质方面对电缆测井技术所获取的参数要求也越来越高。为了更好地获取小井眼尺寸井壁岩心样本,助力油气田高效探勘开发,通过对取心仪井下仪器关键零部件电子控制短节和机械液压短节的创新设计与模拟分析,研制了适用于高温、高压、小尺寸井眼的大直径旋转井壁取心仪(MRCT-dumpy)。通过功能测试和5口井作业应用表明,大直径旋转井壁取心仪钻头性能及取心电机性能均得到充分验证,其热管理系统满足作业需要,符合设计要求;该取心仪取心功能正常,最高单趟收获岩心43颗,满足小井眼大直径取心作业要求。该仪器的设计与应用可为后期同类技术的发展提供指导。

MEMS矢量水听器敏感结构的后CMOS释放工艺研究

纤毛式微机电系统(MEMS)矢量水听器可探测水下质点振速等矢量信息,与互补金属氧化物半导体(CMOS)集成能够很大程度地提升其性能。针对纤毛式MEMS矢量水听器的CMOS集成提出了一种方案,该方案在MEMS后处理工艺中,利用侧墙保护和各向异性湿法腐蚀从正面释放水听器的十字梁敏感结构。整个后处理过程不需要光刻,降低加工难度的同时,保证了加工结构的精确性。设计出了一种验证性的工艺流程,具体分析了4种不同结构的湿法腐蚀过程。最终完成了这4种结构的工艺流片,对实验结果进行了分析。实验验证了该方案的可行性,为纤毛式MEMS矢量水听器的CMOS集成奠定了基础。

基于大高宽比CD-AFM探针的设计与制备

针对传统原子力显微镜(AFM)探针和关键尺寸原子力显微镜(CD-AFM)探针受限于针尖有效扫描高度较低,无法对深沟槽和大悬垂侧壁结构进行精准扫描成像的问题,提出了一种大高宽比针尖结构的新型CDAFM探针设计与制备方案。开发的新型CD-AFM探针针尖有效高度为5.1~5.8μm,高宽比达到14,相较于传统硅基CD-AFM探针,其有效高度提升了约4倍。利用开发的探针完成了标称深度为2.3μm、深宽比为4.6的深沟槽样品测试。

双驱同步橡胶齿轮泵式滤胶机滤网孔径对胎侧胶性能的影响

采用一种双驱同步橡胶齿轮泵式滤胶机对轮胎胎侧胶进行过滤,研究滤网孔径对胎侧胶性能的影响。结果表明:经过过滤的胶料的性能优于未过滤的胶料,且采用孔径0.070 mm(200目)滤网过滤的胶料的硫化特性、物理性能和耐屈挠性能最优,Payne效应最弱,动态力学性能较好;与未经过过滤的硫化胶相比,采用0.070 mm孔径滤网过滤的硫化胶的拉伸强度提高33.0%,撕裂强度提高33.3%,平均龟裂等级降低3级。

基于线性诱导的高速公路隧道边墙效应调控方法研究

文中提出线性诱导理念,基于E-prime平台开展室内仿真模拟试验,并以30名被试者的反应时间和眼动数据作为评价指标衡量调控方法的有效性.结果表明:线性诱导方案能有效改善高速公路隧道边墙效应,降低驾驶人的反应时间,缓解驾驶人的紧张程度;采用点状设施方案或线性诱导方案的点状设施+短线条设施时,亮灯率对驾驶人反应时间有显著影响;采用点状设施+短线条设施+长线条设施或点状设施+短线条设施+长线条设施+环状设施的方案时,亮灯率对驾驶人反应时间没有显著影响,且方案为后者时,驾驶人反应时间的变异系数小,瞳孔面积变化率更稳定.

滤筒除尘器喷吹孔孔径的优化

【目的】为控制各个喷吹管气流量的均匀性,对喷吹管上的喷吹孔径进行优化,提高滤筒除尘器清灰效果。【方法】自制高压脉冲喷吹气流量测量装置对现有喷吹管气流量进行测定,采用光纤传感分析仪测试除尘器滤筒各部分的侧壁压力峰值,分析各滤筒清灰效果不均匀的原因;以滤筒各部位侧壁压力峰值作为清灰均匀性效果评估指标,优化喷吹孔径。【结果】优化前4个喷吹孔径均为19 mm,喷吹孔的气流量依次为13.69、 14.78、 16.03、 16.93 L,对应4个滤筒上、中、下部侧壁压力峰值的最小值分别为最大值的37%、 26%、 20%,气流量均匀度标准差为1.41;优化后4个喷吹孔径分别为23、 20、 18、 17 mm,喷吹气流量依次为14.05、 15.08、 15.87、 16.13 L,对应4个滤筒上、中、下部测壁压力峰值的最小值为最大值的56%、 56%、 53%,气流量均匀度标准差降为0.93。【结论】优化后的喷吹管气流量均匀化程度提高,可实现滤筒除尘器的均匀清灰。