Analysis of Passive Limited Supporting Force of Curved Shield Tunnel Excavation FaceEI北大核心

Research purposes: In the construction process of curved shield tunnels, the force of excavation face is extremely complex and the stability is difficult to control, so it is very likely that the thrust of the jack will cause uplift of the soil in front because of passive failure. Taking the sand strata as an example, this paper established a combination model of "inverted ladder-wedge prism" to reveal that the soil in front of the excavation face of curved shield tunnels uplifts up because of passive failure based on the silo theory and limit equilibrium method, and deduced the calculation method of passive limited supporting force for curved tunnels. Then, we confirmed the accuracy and reliability of this model and calculation method through programing and simulating. Research conclusions:(1) The passive limited supporting force increases with the increase of buried depth and internal friction angle, and the growth rate gradually increases. (2) When the radius of the line is less than 200 m and the internal friction angle is more than 25 degrees, the passive limited supporting force is very sensitive to the curvature radius, and when the radius is more than 800 m, the passive limited supporting force is almost no difference with straight tunnels. (3) The numerical results indicate that the numerical solution is consistent with the theoretical solution and the difference is quite small. (4) The research results can provide theoretical basis for determining the passive limited supporting force in the constructions of similar curved shield tunnels especially small turn radius shield tunnels. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

PHOSPHORYLATION OF THE MYELOID ZINC FINGER PRO TEIN MZF－1 IS DIFFERENTIALLY REGULATED DURING MYELOPOIESIS

ＰＨＯＳＰＨＯＲＹＬＡＴＩＯＮＯＦＴＨＥＭＹＥＬＯＩＤＺＩＮＣＦＩＮＧＥＲＰＲＯＴＥＩＮＭＺＦ－１ＩＳＤＩＦＦＥＲＥＮＴＩＡＬＬＹＲＥＧＵＬＡＴＥＤＤＵＲＩＮＧＭＹＥＬＯＰＯＩＥＳＩＳＨｕｉＰｅｉ；ＭａｒｉａＲ．Ｂａｅｒ，ＰｅｔｅｒＧ．Ｂｒａｄｆｏｒ...     

轨道车辆直流牵引电机噪声的分析与研究

本文在城市轨道车辆牵引电机噪声测试的基础上,分析了牵引电机噪声的产生机理和频率分布以及对室内外环境的影响和传播途径。最后提出了牵引电机的降噪措施。     

LOSS OF NUCLEUS BASALIS MAGNOCELLULARIS，BUT NOT SEPTAL，CHOLINERGIC NEURONS CORRELATES WITH PASSIVE AVOIDANCE IMPAIRMENT IN RA

ＬＯＳＳＯＦＮＵＣＬＥＵＳＢＡＳＡＬＩＳＭＡＧＮＯＣＥＬＬＵＬＡＲＩＳ，ＢＵＴＮＯＴＳＥＰＴＡＬ，ＣＨＯＬＩＮＥＲＧＩＣＮＥＵＲＯＮＳ　ＣＯＲＲＥＬＡＴＥＳＷＩＴＨＰＡＳＳＩＶＥＡＶＯＩＤＡＮＣＥＩＭＰＡＩＲＭＥＮＴＩＮＲＡＴＳＴＲＥＡＴＥＤ　ＷＩＴ...     

THE EFFECT OF VITAMIN C INTAKE ON GLYCOHEMOGLOBIN MEASUREMENTS

ＴＨＥＥＦＦＥＣＴＯＦＶＩＴＡＭＩＮＣＩＮＴＡＫＥＯＮＧＬＹＣＯＨＥＭＯＧＬＯＢＩＮＭＥＡＳＵＲＥＭＥＮＴＳＦａｎｇＺｈｉｙｕ；ＳｕＭｉｎｇ，Ｒ．Ｒ．Ｌｉｔｔｌｅ，Ｈ．Ｍ．Ｗｉｅｄｍｅｙｅｒ，Ｄ．Ｅ．Ｇｏｌｄｓｔｅｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｉ...     

Variation in predicting pantograph–catenary interaction contact forces,numerical simulations and field measurements

The contact force between the pantograph and the contact wire ensures energy transfer between the two. Too small of a force leads to arching and unstable energy transfer, while too large of a force leads to unnecessary wear on both parts. Thus, obtaining the correct contact force is important for both field measurements and estimates using numerical analysis. The field contact force time series is derived from measurements performed by a self-propelled diagnostic vehicle containing overhead line recording equipment. The measurements are not sampled at the actual contact surface of the interaction but by force transducers beneath the collector strips. Methods exist for obtaining more realistic measurements by adding inertia and aerodynamic effects to the measurements. The variation in predicting the pantograph–catenary interaction contact force is studied in this paper by evaluating the effect of the force sampling location and the effects of signal processing such as filtering. A numerical model validated by field measurements is used to study these effects. First, this paper shows that the numerical model can reproduce a train passage with high accuracy. Second, this study introduces three different options for contact force predictions from numerical simulations. Third, this paper demonstrates that the standard deviation and the maximum and minimum values of the contact force are sensitive to a low-pass filter. For a specific case, an 80?Hz cut-off frequency is compared to a 20?Hz cut-off frequency, as required by EN 50317:2012; the results show an 11% increase in standard deviation, a 36% increase in the maximum value and a 19% decrease in the minimum value.     

Efficiency in Nigerian ports: handling imprecise data with a two-stage fuzzy approach

This article is focused on assessing the efficiency of six major Nigerian ports from 2007 to 2013 by applying a two-stage fuzzy-based methodology adequate to handle imprecise data. More precisely, fuzzy data envelopment analysis models for traditional assumptions with respect to scale returns are employed to assess the productivity of Nigerian ports over the course of time. In the second stage, fuzzy regressions based on different rule-based systems are used to predict the relationship of a set of contextual variables on port efficiency. These contextual variables are related to different aspects of port service level, berth utilization, accessibility, cargo type, and operator type. The results reveal the impact of operator and cargo type on efficiency levels. Policy implications for Nigerian ports are derived.     

Cohort analysis of driving cessation and limitation among older adults

Automobiles are central to participation in economic, social, and cultural activities in the United States. The ability to drive as one ages is fundamental to the quality of life among older adults. Driving rates decline significantly with age. Researchers using cross-sectional data have studied the reasons former drivers have stopped driving, but few have followed individuals over time to examine changes in relationships among driving cessation, socio-demographics, and health conditions. We used longitudinal data from a national sample of 20,000 observations from the University of Michigan Health and Retirement Study (HRS) to examine relationships among demographic variables, health conditions, and driving reduction and driving cessation. Longitudinal data allow analysis of generational differences in behavior, a major advantage over cross-sectional data which only allow comparisons of different people at one point in time. We found, like many other studies, that personal decisions to limit and eventually stop driving vary with sex, age, and health conditions. In addition, unlike most previous studies, we also found that those relationships differ by birth cohort with younger cohorts less likely to stop and limit their driving than their older counterparts. The findings indicate an evolution in the association between driving cessation and its causes.

     

通过多转子防护装置提高潮汐水轮机性能的策略（英文）

Constructive interference between tidal stream turbines in multi-rotor fence configurations arrayed normally to the flow has been shown analytically, computationally, and experimentally to enhance turbine performance. The increased resistance to bypass flow due to the presence of neighbouring turbines allows a static pressure difference to develop in the channel and entrains a greater flow rate through the rotor swept area. Exploiting the potential improvement in turbine performance requires that turbines either be operated at higher tip speed ratios or that turbines are redesigned in order to increase thrust. Recent studies have demonstrated that multi-scale flow dynamics, in which a distinction is made between device-scale and fence-scale flow events, have an important role in the physics of flow past tidal turbine fences partially spanning larger channels. Although the reduction in flow rate through the fence as the turbine thrust level increases has been previously demonstrated, the within-fence variation in turbine performance, and the consequences for overall farm performance, is less well understood. The impact of turbine design and operating conditions, on the performance of a multi-rotor tidal fence is investigated using Reynolds-Averaged Navier-Stokes embedded blade element actuator disk simulations. Fences consisting of four, six, and eight turbines are simulated, and it is demonstrated that the combination of device-and fence-scale flow effects gives rise to cross-fence thrust and power variation. These cross-fence variations are also a function of turbine thrust, and hence design conditions,although it is shown simple turbine control strategies can be adopted in order to reduce the cross-fence variations and improve overall fence performance. As the number of turbines in the fence, and hence fence length, increases, it is shown that the turbines may be designed or operated to achieve higher thrust levels than if the turbines were not deployed in a fence configuration.     

Challenges in Collaborative Governance for Coastal Restoration: Lessons from the Caernarvon River Diversion in Louisiana

In an effort to restore deteriorating coastal wetlands in Breton Sound, Louisiana, a diversion of Mississippi River water into the estuarine ecosystem has been operated at Caernarvon, Louisiana, since 1991. The diversion was implemented after a relatively long collaborative planning process beginning in the 1950s. The Caernarvon Interagency Advisory Committee, an official panel of stakeholders, considers scientific aspects of the freshwater inflow and stakeholder inputs in developing an operational plan, which internalizes stakeholder conflicts, while accomplishing goals of restoring the coastal ecosystem. Even though fishery representatives are committee members, local oyster fishers filed lawsuits in federal and state courts from 1994 through 2005, claiming damages to their oyster beds. These lawsuits were initially successful in state courts but were reversed by the Louisiana Supreme Court. The federal suits were unsuccessful. Following these lawsuits, voters in Louisiana in 2000 amended the State Constitution to protect coastal restoration projects against lawsuits reflecting increase in overall statewide support. Increasing scientific knowledge has contributed significantly to diversion operation. For better collaborative governance, efforts to increase common understanding among stakeholders will be needed, and a process to compensate interests of stakeholders suffering from impacts of restoration projects at an earlier stage should be institutionalized.