动态贝叶斯网络在管廊电缆舱火灾风险评估中的应用研究

电缆舱是城市综合管廊必不可少的舱体,担负着至关重要的电力传输功能。电缆舱火灾不仅会导致能源供应中断,还可能对周边生态环境和公共安全构成严重威胁。为了对这一特殊空间内的火灾风险进行系统的分析,构建蝴蝶结(Bow Tie,BT)模型并映射到动态贝叶斯网络(Dynamic Bayesian Network,DBN),通过实例分析确定某地下管廊电缆舱起火的先验概率与后验概率,识别主要风险源及对电缆起火的敏感度,探究在具备不同灭火屏障条件下的电缆舱火灾发展态势。结果表明,单相接地故障、制造缺陷、绝缘损坏、连接缺陷等是导致电缆舱起火的关键因素,并且随时间推进,各种不利后果发生概率呈上升趋势。这一发现凸显了及时有效的预防与早期干预措施对于遏制电缆舱火灾扩散的重要性。

高速列车设备舱风-雪流试验可复现性探究及防积雪优化

为探究风-雪两相流风洞试验对高寒高速列车设备舱内雪粒进入与堆积现象的可复现性和增加滤网密度对设备舱防积雪性能的影响,基于某冰雪风洞试验台对某典型高寒高速列车全尺寸设备舱模型内进雪、积雪进行复现与对比试验研究。复现试验监控裙板进气格栅处的雪粒子流入及底板表面积雪情况,并与实车情况进行对比。对比试验采集了设备舱进气格栅、转向架牵引电机通风机处的气流流速及设备舱内的积雪分布与质量。试验结果表明:风-雪两相流风洞试验可以良好再现设备舱裙板处雪粒的进入,雪粒在舱内的自然下沉与堆积,积雪层随试验时长增加不断增厚,有效复现全尺寸设备舱内积雪情况;滤网密度增加对设备舱进气格栅及舱内通风机进、出风口处的气流流速影响较小,夏季高温条件下的设备正常进风无影响;在风-雪环境下,滤网密度增加有效缩短进入设备舱的雪粒子纵深迁移运动距离,对雪粒子入舱阻滞作用显著。高密度滤网可降低舱内迎风侧平均积雪厚度55.1%,舱内总积雪量减少66.3%。对裙板格栅滤网进行加密可有效提升设备舱防进雪性能,减少相关设备在冬季低温条件下的故障率。

多种舰艇的医疗卫生舱室爆炸损伤模拟研究

目的:研究在爆炸打击作用下多种舰艇的医疗卫生舱室的损伤结果和结构响应规律。方法:首先,基于爆炸载荷理论将舱室结构等效为T型材板架,建立尺寸(长×宽×高)分别为2.8 m×2.6 m×2.3 m、3.2 m×3.2 m×2.4 m、4.2 m×3.2 m×2.5m、5.4 m×4.0 m×2.6 m的4种医疗卫生舱室有限元模型。其次,采用ABAQUS仿真软件建立爆炸损伤模型,并设置爆炸位置为舱内中心和舱壁外侧、三硝基甲苯(trinitrotoluene,TNT)当量为10、100 kg进行爆炸损伤模拟;最后,分析10与100 kg TNT当量下舱内中心与舱壁外侧爆炸位置的爆炸损伤结果。结果:在舱内中心位置爆炸后,10 kg TNT会造成局部变形,且对大规模舱室影响区域有限,而100 kg TNT对舱室功能区域的破坏范围较大,且小规模舱室出现严重变形与破坏;在舱壁外侧位置爆炸后,10 kg TNT下小规模舱室的局部区域出现破口,大规模舱室舱壁的局部区域出现变形,而100 kg TNT下所有舱室舱壁出现大面积破口。结论:对于规模较小且结构强度较弱的舱室,爆炸载荷使其变形与损伤的结果更加严重,爆炸冲击产生的破口形状更复杂。而规模较大且舱壁与扶强材较厚的舱室具有一定的抗爆性能,大当量爆炸载荷会对此类舱室的局部结构产生严重破坏。

从《翻译适应选择论》看林纾与魏易对Uncle Tom's Cabin的翻译

本文运用《翻译适应选择论》,以译者的适应/选择为视角,就林纾与魏易对Uncle Tom's Cabin翻译的全过程展开描述与分析,旨在说明二位译者对原语文本及翻译策略、方法的选择是其对"需要"、"能力"及"翻译生态环境"适应与选择的结果。

某混凝土筒仓结构设计研究

圆形筒仓设计充分利用了薄壁筒壳结构的优越性,薄壁的配筋与受力、边缘效应、地震等因素有关,在设计过程中需要重点考虑。基于某实际工程案例,采用Midas Gen进行了整体建模计算,通过深仓贮料和浅仓贮料计算了筒仓侧壁的受力,并对各荷载工况进行了分析。由于地震力对筒仓会产生较大影响,分析了不同地震工况下地震力的大小。在此基础上,贮料荷载对于仓壁的水平作用较为明显,通过荷载组合对筒仓侧壁进行设计研究。总结了侧壁配筋的控制因素,为筒仓设计提供帮助。

Analysis and Interpretation of the Social Reality Reflected in Harriet Beecher Stowe's Uncle Tom's Cabin

The basic assumption of Marxist criticism is that those who control a society's economy also control or largely influence its material, cultural, and intellectual products. The Marxist criticism theory in Uncle Tom's Cabin is about the reality of liberation theology, and twentieth-century political resistance movement in order to expose the evilness of slavery.

气容水舱消减流量脉动数值仿真研究

管路系统是水下航行器与外界水环境重要的交互通道,工作过程中将产生流量和压力脉动,并激发振动和噪声,严重影响水下航行器的隐蔽性能。结合水下航行器管路系统中气容水舱特性和蓄能器吸收脉动原理,提出利用气容水舱消减脉动方法,研究不同工况下气容水舱消减流量脉动性能,结果表明:当气体压力由0.8 MPa增大至1.6 MPa,脉动率由14.96%降低至6.40%;脉动频率由2.0 Hz增大到6.0 Hz,脉动率由14.07%降低至10.69%;脉动幅值由1.0 m/s增大到4.0 m/s,脉动率由13.19%降低至10.64%。气容水舱可以有效消减进口管道的低频率小幅值流量脉动,实现系统平稳通流,满足管路系统消减流量脉动需求。

通风策略对飞机客舱空气质量及舒适度影响的研究

机舱内空气质量在多个方面对乘客有深远的影响,其中挥发性有机物(VOC)和二氧化碳(CO_(2))等的影响尤为突出。因飞机客舱的独特结构,导致客舱内湿度低、压力低。本文旨在探讨机舱空气质量及乘客健康的影响,通过采用了2(占用率)×4(空气通风制度)的因子设计,对参与者进行随机分配,最终确定在标准客舱通风制度下环境条件对参与者幸福感及健康方面的影响。

磷酸铁锂储能预制舱火灾烟气扩散及温度变化规律

随着电化学储能的大规模应用,储能预制舱安全问题日益突出。对储能预制舱内不同热失控位置下的储能预制舱火灾差异进行研究,可以帮助设计更有效的监测和灭火系统,提升储能预制舱安全性能。因此,模拟研究不同热失控位置下储能预制舱火灾烟气扩散及温度变化规律具有重要意义。文中基于直接数值模拟和大涡模拟方法,依据实际储能预制舱尺寸构建磷酸铁锂储能预制舱的数值模型,引入更符合火情发展的t2模型,通过模拟不同热失控位置的火灾情境,研究储能预制舱内烟气扩散和温度变化规律。仿真结果表明,热失控的位置不同,烟气具有不同的动态行为,热失控位置越靠近底层,烟气运动越快,充满储能预制舱时间越短。当热失控位置靠近舱顶,在高度1.85 m以上的区域温度较高,并伴随显著的温度波动时,储能预制舱水平方向上的温度差显著增大。文中进一步分析额定容量为1.2 MW·h的标准储能预制舱的灭火系统设计方案,发现全氟己酮灭火系统在喷淋强度为20 L/(min·m2)、喷淋角度为120°、全氟己酮灭火剂粒径大小为50μm时,能有效控制火灾,减少火灾造成的损害。文中的研究成果可为储能预制舱内监测预警装置分布式布署策略及消防安全设计提供理论指导。

一种汽车智能空气自动化循环系统的设计

针对夏季汽车在户外暴晒后,驾乘舱环境恶化这一问题,设计出一种汽车智能空气自动化循环系统。该系统基于装备手动空调的乘用车,根据驾乘舱内外的温度变化和空气质量,综合控制太阳能遮阳储能系统、半导体降温系统和换气系统等,自动调整自动化循环降温设备工况,初步实现了行车和驻车2种状态下智能降温、净化空气、延缓老化、节能省油、提升动力、杀菌除臭六位一体的效果,改善了驾乘人员工作环境。

Experimental Study on Occupant's Thermal Responses under the Non-uniform Conditions in Vehicle Cabin during the Heating Period

The existing investigations on thermal comfort mostly focus on the thermal environment conditions, especially of the air-flow field and the temperature distributions in vehicle cabin. Less attention appears to direct to the thermal comfort or thermal sensation of occupants, even to the relationship between thermal conditions and thermal sensation. In this paper, a series of experiments were designed and conducted for understanding the non-uniform conditions and the occupant＇s thermal responses in vehicle cabin during the heating period. To accurately assess the transient temperature distribution in cabin in common daily condition, the air temperature at a number of positions is measured in a full size vehicle cabin under natural winter environment in South China by using a discrete thermocouples network. The occupant body is divided into nine segments, the skin temperature at each segment and the occupant＇s local thermal sensation at the head, body, upper limb and lower limb are monitored continuously. The skin temperature is observed by using a discrete thermocouples network, and the local thermal sensation is evaluated by using a seven-point thermal comfort survey questionnaire proposed by American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc（ASHRAE） Standard. The relationship between the skin temperature and the thermal sensation is discussed and regressed by statistics method. The results show that the interior air temperature is highly non-uniform over the vehicle cabin. The locations where the occupants sit have a significant effect on the occupant＇s thermal responses, including the skin temperature and the thermal sensation. The skin temperaWa-e and thermal sensation are quite different between body segments due to the effect of non-uniform conditions, clothing resistance, and the human thermal regulating system. A quantitative relationship between the thermal sensation and the skin temperature at each body segment of occupant in real life traffic is presented. The investigation result indicates that the skin temperature is a robust index to evaluate the thermal sensation. Applying the skin temperature to designing and controlling parameters of the heating, ventilation and air conditioning（HVAC） system may benefit the thermal comfort and reducing energy consumption.

从翻译规范理论看Uncle Tom's Cabin的两个汉译本

拟以图里的翻译规范理论为视角,通过对不同历史背景下出版的UncleTom’s Cabin两个不同汉译本进行对比分析,考察译者在翻译过程中所遵循的翻译规范,并解释两个汉译本中存在的诸多不同的翻译现象。

Design and Experimental Evaluation of PID Controller for Digital Electro-Pneumatic Cabin Pressure Control System

The performance of the designed digital electro-pneumatic cabin pressure control system for the cabin pressure schedule of transport aircraft is investigated.For the purpose of this study,an experimental setup consisting of a simulated hermetic cabin and altitude simulation chamber is configured for cabin pressure control system operation.A series of experimental tests are executed to evaluate the performance of the cabin pressure control system.The parameters of the PID controller are optimized.In the optimization process,the variation regularity of the rate of cabin pressure change under various conditions is considered.An approach to prioritize the control of the rate of change of cabin pressure based on the flight status model is proposed and verified experimentally.The experimental results indicate that the proposed approach can be adopted for the designed digital electro-pneumatic cabin pressure control system to obtain a better cabin pressure schedule and rate of cabin pressure change.

Experimental Verification and Research for the Distortion in the Integrated Frequency Responses of the High-Pressure Sealed Cabin and Magnetic Field Sensor

Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to complete measurements. To protect the magnetic field sensors from intense erosion and high pressure, suitable high-pressure sealed cabins must be designed to load them. For the consideration of magnetic measurement and marine operation, the sealed pressure cabin should be nonmagnetic and transportable. Among all optional materials, LC4 super.hard aluminum alloy has the highest performance of price/quality ratio to make the sealed pressure cabin. However, it does not mean that the high-pressure sealed cabin made using LC4 will be perfect in performance. In fact, because of its weak magnetism, the pressure cabin made using LC4 has distorting effect on frequency responses of the magnetic field sensors sealed in it. This distorting effect does not affect the use of the magnetic field sensor, but if we want to eliminate its effect, we should study it by experimental measurements. In our experiment tests, frequency sweep magnetic field as excitation signal was used, and then responses of the magnetic field sensor before and after being loaded into the high-pressure sealed cabin were measured. Finally, normalized abnormal curves for the frequency responses were obtained, through which we could show how the high-pressure sealed cabin produces effects on the responses of the magnetic field sensor. Experimental results suggest that the response distortion induced by the sealed pressure cabin appears on mid- and high-frequency areas. Using experimental results as standardization data, the frequency responses collected from seafloor magnetotelluric measurements can be corrected to restore real information about the seafloor field source.

A Preliminary Numerical Investigation of Airborne Droplet Dispersion in Aircraft Cabins

The emergence of the novel coronavirus has led to a global pandemic which has led to the airline industry facing severe losses. For air travel to recover, airlines need to ensure safe air travel. In this paper, the authors have modeled droplet dispersion after a single breath from an index patient. Computational Fluid Dynamics (CFD) simulations are conducted using the k-ωSST turbulence model in ANSYS Fluent. The authors have taken into consideration several parameters such as the size of the mouth opening, the velocity of the cabin air as well as the number of droplets being exhaled by the index patient to ensure a realistic simulation. Preliminary results indicate that after a duration of 20 s, droplets from the index patient disperse within a 10 m2 cabin area. About 75% of the droplets are found disperse for up to 2 m axially behind the index patient. This could possess an enhanced risk to passengers sitting behind the index patient. Ultimately, this paper provides an insight into the potential of CFD to visualise droplet dispersal and give impetus to ensure that necessary mitigating measures can be taken to reduce the risk of infection through droplet dispersal.

Current studies on air distributions in commercial airliner cabins

Abstract Air distribution in commercial airliner cabins is very important for the comfort and health of passengers and crew. Experimental measurements, computational fluid dynamics （CFD） simulations, and inverse modeling are state-of-the-art methods available for studying the air distri- bution. This paper gave an overview of the different experimental models, such as scale models, simplified models, full-scale mockups, and actual air cabins. Although experimental measurements were expensive and time consuming, the data were essential for validating CFD simulations. Different modeling strategies for CFD simulations were also discussed in this paper, including large eddy simulations and Reynolds averaged Navier-Stokes equation modeling. CFD simulations were main stream approaches for studying the air distribution but they could not easily lead to optimal design. Inverse modeling of air distribution has recently emerged into a very powerful and attractive tool for designing the air distribution in airliner cabins, although most of the studies were preliminary.

The scaling laws of cabin structures subjected to internal blast loading:Experimental and numerical studies

This paper presents a combination of experimental and numerical investigations on the dynamic response of scaling cabin structures under internal blast loading.The purpose of this study is to modify the similar relationship between the scaled-down model and the prototype of the cabin structures under internal blast loading.According to the Hopkinson’s scaling law,three sets of cabin structure models with different scaling factors combined with different explosive masses were designed for the experimental study.The dynamic deformation process of the models was recorded by a three-dimensional digital imaging correlation(DIC)method and a 3D scanning technology was used to reconstruct the deformation modes of the specimen.In addition,a finite element model was developed for the modification of the scaling law.The experimental results showed that the final deflection-to-thickness ratio was increased with the increase of the model size despite of the similar trend of their deformation processes.The reason for this inconsistency was discussed based on the traditional scaling law and a modified formula considering of the effects of size and strain-rate was provided.

Protective Design of a Warship Broadside Liquid Cabin

Based on the traditional Smoothed Particle Hydrodynamics (SPH) algorithm, the linked-list search algorithm combined with the variable smoothing length and square support domain was put forward to improve the calculation efficiency and guarantee the calculation accuracy. The physical process of high velocity fragment impact on a broadside liquid cabin was programmed for simulation. The numerical results agreed well with those of the general software ANSYS AUTODYN, which verifies the effectiveness and feasibility of the numerical method. From the perspective of the outer plate thickness of the liquid cabin, the width of the liquid cabin, and incident angle of the fragment, the influence of these parameters on protective mechanisms was analyzed to provide a basis for protective design of a broadside liquid cabin. Results show that the influence of outer plate thickness is not obvious; therefore, the conventional design can be adopted in the design of the outer plate. The width of the liquid cabin has a great influence on the residual velocity of the fragment and the width of the liquid cabin should be designed to be as wide as possible under the premise of meeting other requirements. There is a certain incident angle in which the velocity attenuation of the fragment is most obvious, and the high-pressure zone near the inner plate is asymmetric. The inner plate of liquid cabin should be strengthened according to the hull form, principal dimensions, and vulnerable points.

The Influence of Blocking Mass Parameters on the Vibration Isolation Performance of a Power Cabin

Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-band vibration and sound radiation reduction effect of vibration isolation masses located in a base structure was researched.The influence of the blocking mass’ cross-section size and shape parameters and the layout location of the base isolation performance was discussed.Furthermore,the effectiveness of rigid vibration isolation design of the base structure was validated.The results show that the medium and high frequency vibration and sound radiation of a power cabin are effectively reduced by a blocking mass.Concerning weight increment and section requirement,suitably increasing the blocking mass size and section height and reducing section width can result in an efficiency-cost ratio.

模因论在专门用途英语Cabin English教学中的具体应用研究

模因论是由Dawkins提出的建立在达尔文进化论观点基础上,以阐释文化进化的一种理论。模因促成了语言的起源,而语言的功能就在于传播模因。模因复制和传播的两种方式(基因型模因和表现型模因)以及模因生命周期所包含的四个阶段(同化、记忆、表达和传输)显示在专门用途英语Cabin English教学中,教师可以鼓励并指导学生通过背诵、模仿、创设情境进行角色扮演来提高自己的语言应用能力。