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This study revealed the mechanism of long-term passenger vibration discomfort in high-speed trains and proposed a novel evaluation model to assess it, while the most popular international standard ISO 2631-1 is unsuitable. Here, a field test was conducted to investigate the long-term passenger vibration comfort in high-speed trains under different operation environments by the measurement of the whole-body vibration (WBV) and the subjective ratings of passenger comfort. During the whole sitting period of high-speed train passengers, the phenomena 'compensatory degradation' and 'discomfort accumulation' were found, which meant that the brief termination of vibration cannot fundamentally alleviate passenger vibration comfort. And the vibration comfort can be evaluated by the product of exposure time and the novel vibration acceleration index we proposed. Meanwhile, high-speed trains with higher velocities or running in tunnel environments have higher frequency-weighted WBV amplitude than open-air and lower velocities, which caused more vibration discomfort of passengers. Practitioner Summary: This field study provided data support for ensuring the occupational health of train drivers whose work routes involve a large number of tunnels and improving passenger vibration comfort. Meanwhile, a novel idea was provided for evaluating the vibration comfort of passengers who prolonged exposure to low-amplitude environments.

Discomfort caused by long-term sitting decreases the passenger experience and may lead to musculoskeletal diseases, and this has become one of the main problems for passengers of high-speed railways. However, the comfort degradation mechanism during long-term sitting in high-speed railways is still unknown. This study aimed to reveal passengers’ sitting comfort degradation mechanism in high-speed railways. By carrying out long-term sitting tests on high-speed trains running on the Shanghai-Kunming line, the dynamic interface pressure and subjective comfort including overall and regional comfort of seven participants were obtained. Machine learning models and statistical analysis methods were combined for data analysis to reveal the effect of regional comfort and the contribution of sitting duration during the process of sitting comfort degradation. The results show that overall comfort is most significantly influenced by the comfort of the shoulders, waist and buttocks. The seats play different roles before and after 20 minutes during long-term sitting and there is a lag between the fatigue occurring and being offset. Therefore, the structure of seats affects overall comfort by affecting important regional comfort, and a long-term sitting test is necessary for accurate seat assessment. The comfort degradation mechanism can be used to define standards for long-term sitting comfort or provide guidance for seat evaluation, and the design and evaluation plan mentioned in this article for second-class seats can be applied to other cases with limited accommodating space.

Passenger ride comfort has become a focus of attention in rail transportation equipment design, manufacture and later operation to meet people's demand for travel quality. However, comfort is a very subjective concept, which is difficult to quantify and evaluate directly, and can be affected by various factors, leading to the corresponding technologies for ride comfort improvement becoming diverse. In this paper, recent research on the assessment method and improvement measures of railway passenger ride comfort is reviewed. The main types of ride comfort are summarized first according to the sources of discomfort, including static comfort, vibration comfort, noise comfort, aural pressure comfort, thermal comfort and visual comfort. The current assessment methods of ride comfort are introduced from the aspects of environmental parameters and human parameters based on the nature of evaluation indicators. Finally, the improvement technologies for each type of ride comfort are presented.

Aural comfort is negatively affected during a train’s passage through various tunnel environments. The objective of this study was to propose a prediction model for determining optimal operation parameter combinations to improve train occupants’ aural comfort. High-speed train model tests, combined with a mathematical transfer model, were used to obtain the interior pressure transients under varying speeds, tunnel lengths and seal indexes. Then, a middle ear finite element model was used to simulate the dynamic responses under the pressure transients, and three indicators were employed to assess the severity of aural sensations. Meanwhile, the aural discomfort were classified into four groups according to the duration. Based on the simulation results, the ordinal regression analysis method was used to reveal the effects of the considered factors on aural comfort. The results indicate that aural discomfort sensations begin when a train runs in the middle of a tunnel but are mitigated when it approaches the tunnel exit. Furthermore, aural discomfort is positively correlated with the train speed and the distance from the driver cabin of the head car but negatively correlated with the seal index and tunnel length. As a conclusion, a mathematical prediction model was established that incorporates factors including the train speed, seal index, tunnel length and car position. It can not only forecast aural sensations under certain operation parameters and tunnel environments but also be used for determining the optimal operation parameters to ensure the best aural sensations for high-speed-train occupants.

We propose a novel and efficient multi-functional optical fiber sensor system based on a dense wavelength division multiplexer (DWDM). This system consists of an optical fiber temperature sensor, an optical fiber strain sensor, and a 48-channel DWDM. This system can monitor temperature and strain changes at the same time. The ranges of these two sensors are from −20 °C to 100 °C and from −1000 μ ε to 2000 μ ε , respectively. The sensitivities of the temperature sensor and strain sensor are 0.03572 nm/°C and 0.03808 nm/N, respectively. With the aid of a broadband source and spectrometer, different kinds and ranges of parameters in the environment can be monitored by using suitable sensors.

BiFe 0.95− x Mn 0.05 Zr x O 3 thin films were prepared on ITO/glass substrates using a sol–gel method. The P–E hysteresis loops before and after the high electric field treatment were measured to investigate the deaging effect of Zr 4+ ions on BiFe 0.95 Mn 0.05 O 3 thin films. It was found that the BiFe 0.95 Mn 0.05 O 3 thin film shows typical double P–E hysteresis loops before the cycling of high electric field, indicating that the film was aged. The double-loop feature fades away gradually with the increase of zirconium doping content from 1 to 3 mol%, demonstrating that Zr 4+ ions indeed have deaging effect on the aged BiFe 0.95 Mn 0.05 O 3 film. Such deaging effect of Zr 4+ ions can be further proved by comparing the asymmetry of the coercive field before and after the cycling of high electric field as well as the charge retaining capability.

The BiFe0.95Mn0.05O3 films were fabricated on Pt/Ti/SiO2/Si and Bi2O3/Pt/Ti/SiO2/Si substrates using a sol–gel process. Saturated square P–E hysteresis loops can be observed at frequencies ranging from 1 to 16.7 kHz for both films. The BiFe0.95Mn0.05O3 film on Bi2O3/Pt/Ti/SiO2/Si exhibits a larger 2Pr (∼156 μC/cm2), smaller 2Ec (∼510 kV/cm), more symmetric P–E loops, stronger charge retaining capability (the loss of ΔP is only 2% after 104 s) and fatigue resistance (no loss of ΔP is observed after 1010 switching cycles) compared to the film deposited directly on Pt/Ti/SiO2/Si. More importantly, the former can be uniformly polarized using a piezoelectric-mode atomic force microscopic system and exhibits a larger piezoelectric coefficient (∼64 pm/V). These results should be due to the Bi2O3 buffer layer, which can favor the grain growth and hence elimination of defect complexes formed between the negatively charged defects such as ( Mn Fe 3 + 2 + ) ′ or ( Fe Fe 3 + 2 + ) ′ and oxygen vacancies.

In this paper, all electro-optic solid immersion lens (EOSIL) is introduced, which is made of GaAs. A reflecting external electro-optic measuring system based on the EOSIL is built. With a hemispherical GaAs EOSIL used as the external probe, 0.7 µm spot size is obtained when the wavelength of the probing beam from a laser diode is 1.3 µm and a microscope objective with 0.3 numerical aperture is used. The principle of the measuring system is analyzed by Jones matrix. By using the system, the electrical signals propagating on a microstrip transmission line are successfully measured. The voltage sensitivity about 5 mV/\(\sqrt {Hz} \) is measured when 10 kHz sinusoidal electric signal is applied on the microstrip line.

In this paper an external electro-optic measuring system based on a hemispherical GaAs probe is presented. By using the system, the electrical signals propagating on a microstrip transmission line are successfully measured. The spatial resolution of the system, which is limited by the focused probing spot size, is about 0.5 micrometers , when the wavelength of the probing beam is 1.3 micrometers .© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.