Power allocation and mode selection methods for cooperative communication in the rectangular tunnel

For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the channel capacity formula derivation was obtained.On the optimal criterion of the channel capacity,the power allocation methods of both amplifying and forwarding(AF) and decoding and forwarding(DF) cooperative communication systems were proposed in the limitation of the total power to maximize the channel capacity.The mode selection methods of single input single output(SISO) and single input multiple output(SIMO) models in the rectangular tunnel,through which the higher channel capacity can be obtained,were put forward as well.The theoretical analysis and simulation comparison show that,channel capacity of the wireless communication system in the rectangular tunnel can be effectively enhanced through the cooperative technology;channel capacity of the rectangular tunnel under complicated conditions is maximized through the proposed power allocation methods,and the optimal cooperative mode of the channel capacity can be chosen according to the cooperative mode selection methods given in the paper.

Excavation of Inlet Tunnels at Geheyan Power Station

The Geheyan Power Station on the Qingjiang river has four inlet tunnels, on the right bank, with its excavation diameter of 11.3 m to 12.5 m, after lining diameter of 9.5 m, axis to axis spacing of 24 m. The thickness of the pillar between tunnels should usually be more than two times of tunnel diameter to ensure the stability of surrounding rock during excavation. In this paper, the excavation methods of tunnels with the pillar thickness as small as the tunnel diameter, such as smooth surface blasting, shotcrete support protection, are emphatically discussed.

Upper Lillooet River Hydroelectric Project： The Challenges of Constructing a Power Tunnel for Run-of-River Hydro Projects in Mountainous British Columbia

The Upper Lillooet River Hydroelectric Project （ULHP） is a run-of-river power generation scheme located near Pemberton, British Columbia, Canada, consisting of two separate hydroelectric facilities （HEFs） with a combined capacity of 106.7 MW. These HEFs are owned by the Upper Lillooet River Power Limited Partnership and the Boulder Creek Power Limited Partnership, and civil and tunnel construction was completed by CRT-ebc. The Upper Lillooet River HEF includes the excavation ofa 6 m wide by 5.5 m high and approximately 2500 m long tunnel along the Upper Lillooet River Valley. The project is in a moun- tainous area; severe restrictions imposed by weather conditions and the presence of sensitive wildlife species constrained the site operations in order to limit environmental impacts. The site is adjacent to the Mount Meager Volcanic Complex, the most recently active volcano in Western Canada. Tunneling conditions were very challenging, including a section through deposits associated with the most recent eruption from Mount Meager Volcanic Complex （-2360 years before the present）. This tunnel section included welded breccia and unconsolidated deposits composed of loose pumice, organics （that represent an old forest floor）, and till, before entering the underlying tonalite bedrock. The construction of this section of the tunnel required cover grouting, umbrella support, and excavation with a combination of road header, hydraulic hammer, and drilling-and-blasting method. This paper provides an overview of the project, a summary of the key design and construction schedule challenges, and a description of the successful excavation of the tunnel through deposits associated with the recent volcanic activity.

Application of Distributed Intelligent Power Supply Technology in Expressway Tunnels

With the coordinated development of today's social economy with science and technology,various advanced technologies are being used in highway engineering,especially the distributed intelligent power supply technology in expressway tunnels,which has a very significant advantage.In order to realize the effective application of this technology and promote the power supply effect in expressway tunnel,this study analyzes the advantages of this technology and its application in expressway tunnel,hoping to provide scientific reference for the application of distributed intelligent power supply technology and the engineering development of expressway tunnels.

Experimental Validation of Improving Aircraft Rolling Power Using Piezoelectric Actuators

Piezoelectric actuators are mounted on both sides of a rectangular wing model. Possibility of the improvement of aircraft rolling power is investigated. All experiment proiects, including designing the wind tunnel model, checking the material constants, measuring the natural frequencies and checking the effects of actuators, guarantee the correctness and precision of the finite element model. The wind tunnel experiment results show that the calculations coincide with the experiments. The feasibility of fictitious control surface is validated.

Some Issues on Cement Grouting of Hydraulic Tunnel

Based on the practices of construction supervision to cement grouting at the reservoir emptying and power tunnels of the TSQ stage Ⅰ Hydropower station, some issues on quality control of cement grouting of hydraulic tunnel are discussed, and corresponding suggestions are put forward for revision of current standard (SL62-94). It is regarded that the refilling grouting could not be used for remedying the thickness of concrete lining; the end sealing of refilling grouting section should not be neglected; higher grouting pressure would be used. For the consolidation grouting, grout return pipe should be placed at the grout hole top for pure pressure type grouting; five-grade water cement ratio of grout mix is suggested; a certain standard should be specified for changing the grout to thicker mix by skipping the intermediate grade; the standard for ending the grouting should be relaxed. In current grouting standard, some terms should be complemented for contact grouting of steel penstock and spiral case and for plug grouting of circular-anchor hole.

Development and Construction of 345 kV Power-Optical Fiber Composite XLPE 2,500 mm2 with Prefabricated Joint

Due to the increasing demand of replacing large capacity overhead lines with underground cables in Korea, KEPCO （Korea Electric Power Corporation） and LS Cable （LS Cable ＆ System） have developed 345 kV optical fiber composite XLPE （cross-linked polyethylene） 2,500 mm2 cable system. This system has been installed in Cheongna district of Incheon city. KEPCO and LS Cable are also planning to build the cooling system in a tunnel in order to reduce the ambient temperature caused by currents. In this paper, the process of development, field installation, and final inspection test of the complete system will be described.

基于锥角控制的下风向风力机功率调节策略

针对中小型下风向风力机开展了功率调节策略研究.首先,对100 W下风向风力机进行了仿真计算和风洞实验,探究了下风向风力机的气动性能;然后,分析了风轮锥角对风力机输出功率和叶根载荷的影响机制,归纳出输出功率与锥角余弦值的三次方正相关,叶根载荷与锥角余弦值的平方正相关;最后,形成了一套基于锥角控制的下风向风力机功率主/被动调节策略.研究结果表明:采用主动调节策略可在超额定风速运行时有效控制风轮输出功率,并可使叶根载荷极值降低14.2%;较控制前,采用被动调节策略可使得在超额定风速运行时,输出功率与额定功率的平均偏差减小20.84 W.两种调节策略皆可实现超额定风速运行时下风向风力机输出功率的有效控制.

电力管廊通风规律及结构布局优化研究

为改善电力管廊的通风效果,依托北京新机场高速公路综合管廊工程,采用数值分析与现场试验的方法,对电力舱通风规律进行系统研究。在得到初步规律的基础上,通过改变通风方式、通风口位置和电缆布局,对比研究机械进风自然排风和自然进风机械排风、通风口设在管廊顶部和两侧、10 k V和110 k V电缆交换位置3类6种工况下的通风效果。结果表明:1)现有正常通风条件下,从进风口到排风口,进风口处气流组织混乱;同时,由于在进风口处气流2次改变运动方向导致能量损失很大,致使可用于驱动管廊内空气的能量减小,通风效果下降,造成能源浪费。2)将通风口(风机)布置在电力舱两侧时,因初始风速与通风方向一致,避免了能量损失,有效提高了通风效果。研究显示,管廊中间断面的平均风速提高了0.31 m/s,变幅达39.6%;温度降低了1.6℃,变幅达6.1%;压力损失降低了13.7 Pa,变幅达30.4%,极大地改善了电力舱通风效果。3)在通风口(风机)位于顶部的条件下,对电缆布局优化后,10 k V电缆表面温度降低3.21℃,110 k V电缆表面温度升高1.68℃,纵断面平均温度下降0.365℃,电缆布局调整有利于降低舱内温度,减少压力损失。

爆破振动下城市管架型热力管道响应与安全研究

以下穿热力隧道的北京冬奥支线区间隧道爆破为背景,建立热力管道三维动力有限元模型,利用锤击测试试验验证了数值模型的可靠性.在数值模型中输入实测的爆破振动波,研究爆破地震波作用下管架型热力管道动态响应.结果表明:爆破地震波作用下,管道结构的有效应力为45.89 MPa,有效应变仅为0.02%,与重力初始作用时结构应力应变分布保持一致,爆破振动对管道结构的作用效应较小;放大输入地震波5~100倍,管道结构的PPV随之等倍数增大,而最大等效应力和最大等效应变的增幅仅为4.5%左右;提取实测地震波低频成分并施加在管道结构上,并不会引起热力管道的应力和应变大幅度增加,管道材料的等效应力均在50 MPa以下.由此可见,地震波峰值和主频对管道应力应变分布影响均较小。具有波纹管膨胀节的架空管道结构受力均匀,变形协调性和抗震性能较好,因工程爆破振动造成破坏的可能性不大.

隧道牵引分区所雷击暂态特性及其二次设备电磁兼容研究

牵引供电系统遭受雷击会在分区所内产生过电压与过电流,对分区所开关柜中二次设备产生瞬态电磁干扰,影响其正常运行。文中针对电气化铁路隧道分区所,建立雷击暂态仿真模型,计算了接触网不同位置遭受雷击时分区所的过电压与过电流,建立了27.5 kV开关柜的电磁场有限元仿真模型,分析开关柜中不同区域的瞬态电场、磁场分布。结果表明:雷击接触网会在分区所内产生幅值较大、频率较高的过电压与过电流,在其作用下开关柜低压室瞬态电场可达147.2 V/m、瞬态磁场可达1.3 kA/m,断路器室前壁处瞬态电场可达822.9 kV/m、瞬态磁场可达15.85 kA/m,超过标准规定的幅值,二次设备需要考虑相应的电磁屏蔽措施。论文结果对牵引供电系统雷击过电压/电流防护以及二次设备电磁兼容设计具有参考价值。

接立面转弯隧洞的侧式出水口水力特性

对于接立面转弯隧洞的侧式出水口,立面转弯隧洞的转弯段将直接影响侧式出水口的水力特性。若立面转弯隧洞参数设计不合理,极易导致侧式出水口内部发生流动分离。选取RSM紊流模型,针对接立面转弯隧洞的侧式出水口进行数值模拟,探究立面转弯隧洞曲率半径R、弯道后直隧洞长度L及转弯角度α等参数对出水口水力特性的影响规律,并对隧洞内流动过程进行了讨论。增加立面转弯隧洞曲率半径R和弯道后直隧洞长度L能显著改善出水口的水力指标。当曲率半径R≥12 D(D为隧洞直径)、弯道后直隧洞长度L≥16 D时,侧式出水口内部无明显流动分离,拦污栅断面流速分布均匀且无反向流速区。研究成果将对抽水蓄能电站侧式进/出水口的设计提供指导。

公路隧道风光水储互补发电系统容量配置研究

为降低公路隧道的电力运营成本,探究可再生能源互补发电系统在公路隧道的应用前景,研究合适的容量配置求解方法。建立利用风、光、水和储能设备的互补发电系统为公路隧道提供电力资源。以特长公路隧道(总长7.1 km)为估算模型,采用改进后的粒子群优化算法,即离散型自适应粒子群优化算法,以全生命周期的建设成本和设备维护成本最小为目标函数,以缺电负荷率(LPSP)和储能电池的状态为约束,对风力发电设备、光伏发电设备、水力发电设备和储能设备的最优容量配置进行求解。结果表明:1)对比标准粒子群算法,离散型自适应粒子群优化算法的总投入成本更少,寻优能力更强;2)对比该隧道1年的用电成本,前期投入将在5年内回本;3)在风光水储互补发电系统的设备全生命使用周期的20年内,该隧道可节省1 920.39万元电费。

两条轴线平行布置的泄洪洞出口联合消能工布置形式研究

针对芝瑞抽水蓄能电站下水库两条轴线平行布置的泄洪排沙洞,原设计方案出口联合消能工存在消能效果差的问题,通过选用单体正态水工模型,基于水力相似准则进行水工模型试验,对出口联合消能工的布置形式进行研究。试验实测数据表明,最终推荐方案可有效提高消能效率、改善水流流态、优化设计方案,并达到了减少工程投资的目的,有效地解决了轴线平行布置的泄洪洞出口联合消能问题。

抽蓄电站无压隧洞交叉区体型优化试验研究

交叉无压隧洞交汇区域水流的水力特性复杂,无压隧洞交叉区体型及交汇口水流水力特性的研究对确保水利枢纽的安全运行具有重要的工程意义。基于物理模型试验,对某抽水蓄能电站下水库高落差泄洪排沙洞和放空洞交叉区体型进行优化,最终确定圆弧连接+交叉角21°的交叉区体型。对比分析圆弧连接+交叉角21°的交叉区优化体型下特征试验工况的水力特性。结果表明,6种特征试验工况下,泄洪排沙洞和放空洞交叉口及下游均为急流,明流泄洪且流态较稳定,均在交汇口下游右边直墙处形成最大水深,水深低于直墙高度,满足水面线不宜超过直墙范围的要求。

抽水蓄能电站无压泄洪洞台阶消能型式研究

基于甘肃某抽水蓄能电站泄洪洞洞内消能设计,探讨在流量及底坡恒定的条件下,台阶尺寸与消能率的相关关系,探寻台阶尺寸的初拟原则,采用现行NB/T 10867-2021《溢洪道设计规范》中跌落流上限及滑行流下限的经验公式(坡角范围为2.86°~59.53°)进行台阶消能流态的初步判别,通过Chanson半经验公式理论计算和CFD数值模拟水工隧洞底板布置不同台阶尺寸对应的消能特性。结果表明:在流量及坡度不变的情况下,台阶尺寸(台阶步长及高度)对消能率的影响有限;台阶尺寸越大,水力要素受流动边界条件影响和扰动越明显;初拟台阶尺寸时,应分析水流掺气点位置及出现掺气均匀流位置随台阶尺寸变化向上游移动的速率,同时结合实际边界条件、便于施工及后期运维等方面综合考虑,台阶高差宜控制在0.20~0.60 m。

电力隧道渗漏水成因分析及治理措施研究

电力隧道内电缆数量较多,电缆及其他电力设施对水非常敏感,如果积水淹没电缆(尤其是电缆接头部位),可能会造成事故和损失。文章详细分析了暗挖、盾构等结构形式隧道的渗漏水成因,对管片、环梁、沉降缝、墙体及管孔等部位渗漏水治理措施进行研究,提出了针对性的治理建议并进行了试点应用,为电力隧道渗漏水治理工作提供参考。

基于随机变量概率分析的铁路隧道紧急救援站间距计算方法

考虑着火列车位置和残余运行时间两个随机变量,构建基于列车残余运行的紧急救援站间距定量计算方法并进行验证,分析隧道纵坡、列车制动性能、列车动力损失对紧急救援站间距的影响,以及不同紧急救援站间距的适用条件。研究结果表明,列车动力损失增大、制动性能减弱、隧道纵坡增大均会导致紧急救援站间距减小,其重要性排序为列车动力损失>列车制动性能>隧道纵坡;紧急救援站间距15 km的适用条件为列车动力损失≤1/4;间距20 km的适用条件为列车动力损失≤1/4,且隧道坡度为30‰时,通行列车制动性能应与CRH5相当;间距30 km的适用条件为99.97%保证率的列车残余运行时间≥21.5 min。

大型抽水蓄能电站长直型隧洞风尘迁移规律研究

抽水蓄能电站地下洞室群施工存在通风难度大、风尘迁移变化规律无显著特征等难题,采用DPM气固两相流模型,针对地下洞室群中不同坡度的长直型隧洞进行数值试验研究,重点揭示了典型隧洞在不同施工条件下的风尘迁移规律及小粒径沉降粉尘分布特征。研究表明:不同区域粉尘质量浓度随风机风速的增大呈下降趋势,当风速增至21 m/s时开始升高;掌子面附近区域粉尘质量浓度随供风距离的增大呈上升趋势,当供风距离大于25 m时,风机风速不再满足隧洞内通风要求;掌子面附近区域粉尘质量浓度随隧洞坡度的增大呈显著上升趋势,通风管附近出现明显的粉尘空白带;小粒径沉降粉尘分布特征由通风管位置决定,沉降粉尘颗粒最多处位于通风管出口与掌子面之间,粒径分布较广,呈正态分布规律,在通风管出口正后方处急剧下降,并沿隧洞出口方向数量逐渐减少,平均粒径逐渐减小;流出洞外的粉尘颗粒平均粒径偏小。本研究可为抽水蓄能电站地下洞室群整体施工设计提供参考。

某特长铁路隧道斜井转正洞施工通风方式研究

为研究铁路隧道施工通风的最佳方式,以某铁路隧道工程为依托,通过比较不同通风方式所需的风机功率及预计耗损电费选取最佳通风方式,同时利用Fluent软件对最佳通风方式进行数值计算,从而得出风流随距掌子面距离的运移规律。经过对通风方案的比选及数值计算,得出最佳通风方式为大功率串联压入式,其中3号斜井工区正洞段需要132×2kW的风机,4号斜井工区正洞段需要110×2kW的风机。3,4号斜井的斜井段和正洞段纵向风速变化规律均为先增大后减小最后趋于稳定,选取的风机型号可以满足通风需求。风带直径过大时会增加通风阻力,同时还会影响衬砌台车经过。考虑隧道实际施工情况,3号斜井工区斜井段风带直径选取1.8m,正洞段风带直径选取2m;4号斜井工区斜井段和正洞段风带直径均选取1.8m。