Predictive maintenance decision-making for variable faults with non-equivalent costs of fault severities

Predictive Maintenance is crucial for production systems as it helps maintaining the reliability and availability of components/equipment as well as preventing unexpected shutdowns during production. Traditional maintenance strategies mostly focus on the predictive diagnosis of fault types and identical maintenance decisions would be delivered for the equipment with the same fault type. It often results in “over-maintenance” as the variable fault severities may require non-equivalent costs of maintenance resources. To tackle this problem, this paper aims at developing a fault prediction model firstly predicting fault severity and fault type simultaneously and subsequently providing distinguished maintenance strategy for variable faults accordingly, through which the abnormal faults of equipment can be effectively prevented, and machines can be efficiently and economically maintained based on the model suggested decisions. The main works in this study are 1) The fault features based on monitored vibration signals are extracted from multi-domains, and most significant features are selected by L1-Support Vector Machine (L1-SVM) together with variance filtering method; 2) A parallel fault prediction model based on Back propagation Neural Network and Long Short Term Memory Neural Network (BP-LSTM) is proposed, which is used to predict the fault type and fault degree simultaneously; 3) A Deep Q-Network (DQN)-based maintenance decision-making model is established for different fault types with various fault severities.     

Iterative design of MOVE: A situationally appropriate vehicle navigation system

Drivers need assistance when navigating an unfamiliar route. In-vehicle navigation systems have improved in recent years due to the technology advances, but are sometimes problematic because of information overload while driving. To address the attentional demands of reading a map while driving, we have developed the maps optimized for vehicular environments (MOVE) in-car navigation display, which provides situationally appropriate navigation information to the driver through optimization of map information.In this paper, we describe the iterative design and evaluation process that shaped the MOVE system. We describe early map reading and navigation studies that led to early designs for our system. We present a study on visual search tasks that refined the renditions used for the system. Finally, we present a study on the effectiveness of several variations of a contextually optimized route map visualization with a desktop steering system.The result of this study shows that MOVE's contextually optimized navigation information can reduce the driver's perceptual load significantly. Our laboratory experiment shows that the total map display fixation time was decreased six-fold, and the number of glances to interpret the map display were decreased about threefold, when comparing the contextually optimized display to a static display.     

Traffic network equilibrium problems with demands uncertainty and capacity constraints of arcs by scalarization approaches

This paper focuses on the vector traffic network equilibrium problem with demands uncertainty and capacity constraints of arcs, in which, the demands are not exactly known and assumed as a discrete set that contains finite scenarios. For different scenario, the demand may be changed, which seems much more reasonable in practical programming. By using the linear scalarization method, we introduce several definitions of parametric equilibrium flows and reveal their mutual relations. Meanwhile, the relationships between the scalar variational inequality as well as the (weak) vector equilibrium flows are explored, meanwhile, some necessary and sufficient conditions that ensure the (weak) vector equilibrium flows are also considered. Additionally, by means of nonlinear scalarization functionals, two kinds of equilibrium principles are derived. All of the derived conclusions contain the demands uncertainty and capacity constraints of arcs, thus the results proposed in this paper improved some existing works. Finally, some numerical examples are employed to show the merits of the improved conclusions.     

疲劳驾驶时的车速变化特征

通过驾驶模拟实验研究疲劳驾驶时的车速变化特征.模拟实验场景设计为单调的高速公路环境,有15名被试者参加实验,得到14组有效数据.实验实时采集了车速、加速度、车辆位置坐标及时间信息,采集频率为8Hz,并截取了3个不同线形路段上的数据进行分析.实验结果表明,疲劳驾驶时车速偏高,容易超速,但车速高低没有明显变化规律;车速标准差随疲劳程度上升有显著差异(α=0.05),疲劳时的车速标准差较小;疲劳驾驶时加速度频谱由低频成分为主逐渐转变为高频成分为主,或者加速度幅度和能量值显著减小.     

Microprocessors in railway signalling: the Solid-State Interlocking

The paper reviews some of the techniques available to the designer of safety-critical systems and describes their application to the complex engineering requirements of main-line railway signalling, in the form of British Rail's Solid-State Interlocking (SSI). The design of central interlocking and track-side interface equipment is described in terms of the redundancy techniques used and the organization of their hardware and software.     

Composites for automotive on-engine applications

Over the past fifteen years extensive developments have demonstrated the suitability of moulded reinforced polymer composites as replacements for cast and fabricated “bolt-on” engine components in mass produced vehicles and yet little has reached production. The article discusses some of the complex and interacting relationships between material selection, processing options, component design, investment and component costs which influence progress down the route to materials substitution. In a review of the progress already made, the problems resolved and those remaining, it is suggested that the next few years should see this work reach commercial fruition.     

Development of a new real time responding hydrogen fueling protocol

Current Hydrogen Fueling Protocols (HFPs), such as SAE J2601, have been developed for non-communication and communication. They have problems due to the lack of versatility in their scope of application and the efficiency of their application method. The purpose of this study is to develop a new HFP for communication using a Real Time Responding method with outstanding efficiency and versatility. The new HFP was developed using simple model, that played the role of the engine of HFP, and a rigorous model that played the role as the testbed. This new HFP is founded to be more versatile and efficient compared to the existing HFP and to have excellent convenience, stability, safety, and economic feasibility. It is concluded that the new HFP can perform the function for communication only, while the existing HFP is used for both communication and non-communication.     

Factors determining gasoline soot abatement over CeO2–ZrO2-MnOx catalysts under low oxygen concentration condition

Soot oxidation under a low concentration O₂ (0.5% O₂/N₂) was investigated using CeO₂–ZrO₂-MnO_x mixed oxides with varied amounts of MnO_x, in order to gain low temperature catalytic activity and find out the main factors affecting the soot oxidation. The catalytic activity was remarkably improved over these catalysts compared to that of non-catalyst in such a low concentration of O₂. In particular, CeO₂–ZrO₂-MnO_x with 10% MnO_x doping (M10-CZ) showed the highest catalytic activity with its T₅₀ values of 340 °C under tight contact condition. The results of N₂ adsorption-desorption and X-ray diffraction (XRD) indicated that the textural and structural properties were not positive correlation with soot oxidation, are not the main factors affecting the catalytic activity of CeO₂–ZrO₂ and CeO₂–ZrO₂-MnO_x catalysts. The results of oxygen storage capacity (OSC), hydrogen-temperature programmed reduction (H₂-TPR), O₂ temperature program desorption (O₂-TPD), UV Raman spectroscopy (UV Raman) and X-ray photoelectron spectroscopy (XPS) testified that redox ability, oxygen storage capacity, oxygen desorption capacity at low temperature and surface active oxygen species are more important for soot oxidation. The enhancements of the catalytic behavior after MnO_x addition can be due to the improving of the adsorbed, activation and mobility of reactive oxygen species. In this work, these factors about generation and movement of reactive oxygen species are crucial for soot oxidation in a low oxygen concentration condition.     

轨道交通与常规公交计划调度协调模型

根据福利经济学理论,分析了轨道交通与常规公交运营协调系统的消费者剩余和生产者剩余;并以社会福利最大化为目标,分别建立了非协调计划调度模型和计划调度协调模型,同时给出了模型求解步骤。结合算例,对比分析了轨道交通与常规公交计划调度协调实施前后换乘网络的运营效果。结果表明,实行运营协调控制能够增加社会福利,使出行乘客和运营企业都获益。     

A round-robin test of thermal desorption spectroscopy with quadrupole mass spectrometers calibrated by standard conductance element

The results of a round-robin test of thermal desorption spectroscopy (TDS) in which the quadrupole mass spectrometer of each participant was calibrated in-situ by a standard conductance element are reported. The desorption rate from three commercially available reference materials was quantified from the calibration results, and compared among the three participants. The total reported desorption amounts of hydrogen and argon molecules from the reference materials showed agreement within about 10%. The degree of equivalence of three TDS apparatuses was discussed. It is also shown that the quantification of the gas desorption amounts yields us the appropriate relative ratio between desorbed gas species.