Investigation of in-train stability and safety assessment for railway vehicles during braking

Lai Wei,Jing Zeng,Qunsheng Wang 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

In-train stability of railway vehicles has becoming a major concern for railway vehicles, which refers to the jackknifing behavior of couplers under large in-train forces. For the train to train rescue scenario, braking induced impacts from couplers can adversely affect the dynamic performance of the coupled train. It is indicated from field tests that in-train forces if combined with large rotational angles of couplers can produce vertical components, which will further lead to the interference of adjacent carbodies and structural damages. In this paper, the dynamic model of the train and coupler system is developed. The model verifications are conducted by comparing the calculated responses with the tested results. The safety indices are formulated on the basis of which the running safety of the coupled train is evaluated. The propelling test in the laboratory is conducted to reproduce the coupler jackknifing behavior. The quasi-static analysis and anti-jackknifing mechanism under compressing in-train forces are analysed. Parametric studies are then conducted to propose some limitations for the application of train to train rescue. It is indicated from numerical and testing results that the decrease of the braking deceleration or a limitation of the free rotational angle of couplers is beneficial to lower the amplitude of braking induced impacts.

Ethanol and Water Atomization of Like- and Unlike-Doublet Impinging Jets

( Wei Hsiang Lai ),( Shun Jie Yang ),( Wen Non Huang ) 한국액체미립화학회 2005 한국액체미립화학회 학술강연회 논문집 Vol.2005 No.-

The objective of the present study is to further investigate the general influence of the physical properties and environment effects on the mean drop size generated by like- and unlike-doublet impinging jets with 95% ethanol and purified water. The orifice of the injector element are 0.3, 0.5, and 0.7 mm in diameter, with depth-to-diameter ratio of 10, the impinging angle is set to be 60°, 90° and 120° respectively. In order to measure the mean drop size, the jet velocity is varied from 2 m/s to 30 m/s, the environment pressure is designated as 1, 2, 5 and 9 bar. Results show that in liquid shape mode, the larger impinging angle, the lower jet velocity threshold of mode transition is observed. Regarding the liquid film size, an empirical equation can be used to calculate the ψ angle, and the equation induced by Ibrahim et al.(1991) can figure out the film length by multiply a constant, which is related to the viscosity. The SMD of unlike-doublet impinging is highly influenced by the surface tension. High ambient pressure has no effect on film size, but it causes the liquid shape change mode in lower jet velocity.

A Simple Timeout Algorithm for Point-to-Multipoint ABR Service

Wei Kuang Lai,Chien Ting Chen,Chilin Li 한국통신학회 2004 Journal of communications and networks Vol.6 No.1

A Tracking System Using Location Prediction and Dynamic Threshold for Minimizing SMS Delivery

Lai, Yuan-Cheng,Lin, Jian-Wei,Yeh, Yi-Hsuan,Lai, Ching-Neng,Weng, Hui-Chuan The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.1

In this paper, a novel method called location-based delivery (LBD), which combines the short message service (SMS) and global position system (GPS), is proposed, and further, a realistic system for tracking a target's movement is developed. LBD reduces the number of short message transmissions while maintaining the location tracking accuracy within the acceptable range. The proposed approach, LBD, consists of three primary features: Short message format, location prediction, and dynamic threshold. The defined short message format is proprietary. Location prediction is performed by using the current location, moving speed, and bearing of the target to predict its next location. When the distance between the predicted location and the actual location exceeds a certain threshold, the target transmits a short message to the tracker to update its current location. The threshold is dynamically adjusted to maintain the location tracking accuracy and the number of short messages on the basis of the moving speed of the target. The experimental results show that LBD, indeed, outperforms other methods because it satisfactorily maintains the location tracking accuracy with relatively fewer messages.

Crystallization and Luminescence Properties of Polypropylene Fiber Containing Rare Earth Aluminates and a Sorbital Derivative Nucleating Agent

Wei-Jen Lai,Kuo-Chung Cheng 한국섬유공학회 2018 Fibers and polymers Vol.19 No.1

Polypropylene (PP) fibers with a sorbital derivative nucleating agent (SDN) and rare earth aluminates (SrAl2O4:Eu2+,Dy3+) were prepared via melt compounding and melt-spinning. Non-isothermal crystallization kinetics and luminescence properties of PP and luminous PP fibers were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and decay of the afterglow test. The crystallization temperature determined by DSC increasedwith the addition of the nucleating agent during the cooling process from 200 oC. The Jeziorny model successfully described the non-isothermal crystallization behavior of the luminous PP with various SDN contents. The crystal grain size and morphology of the sample with the SDN was different from that without nucleating agent. The luminous PP fabric having high initial brightness intensity, approximately 461 mcd g-1m-2, can be prepared with addition of 10 wt% of rare earthaluminates and 0.5 % of SDN.

Using Adaptive Bandwidth Allocation Approach to Defend DDoS Attacks

Wei-Shen Lai,Chu-Hsing Lin,Jung-Chun Liu,Hsun-Chi Huang,Tsung-Che Yang 보안공학연구지원센터 2008 International Journal of Software Engineering and Vol.2 No.4

Denial of service attacks occur when the attacks are from a single host, whereas distributed denial of service attacks occur when multiple affected systems flood the bandwidth or resources of a targeted system. Although it is not possible to exempt entirely from denial of service or distributed denial of service attacks, we can limit the malicious user by controlling the traffic flow. In the paper, we propose to monitor the traffic pattern in order to alleviate distributed denial of service attacks. A bandwidth allocation policy will be adopted to assign normal users to a high priority queue and suspected attackers to a low priority queue. Simulations conducted in network simulator of our proposed priority queue-based scheme shows its effectiveness in blocking attacking traffic while maintaining constant flows for legitimate traffic.

Daclatasvir plus Asunaprevir in Interferon (± Ribavirin)- Ineligible/Intolerant Asian Patients with Chronic HCV Genotype-1b Infection

( Lai Wei ),( Mingxiang Zhang ),( Min Xu ),( Wan-Long Chuang ),( Wei Lu ),( Wen Xie ),( Zhansheng Jia ),( Guozhong Gong ),( Yueqi Li ),( Si Hyun Bae ),( Yong-Feng Yang ),( Qing Xie ),( Shumei Lin ),( 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1

Aims: The efficacy/safety of daclatasvir (pan-genotypic NS5A inhibitor) plus asunaprevir (NS3 protease inhibitor) in interferon (± ribavirin)- ineligible/intolerant patients with chronic HCV genotype-1b infection from mainland China, Korea and Taiwan was investigated in a phase 3, open-label study. Methods: Patients received daclatasvir 60 mg (tablet) once daily plus asunaprevir 100 mg (soft capsule) twice daily for 24 weeks. The primary endpoint was sustained virologic response at post-treatment Week 24 (SVR24). Results: This study treated 159 patients from mainland China (80%), Korea (11%) and Taiwan (9%), including patients with cirrhosis (33%), IL28B non-CC genotypes (40%), and aged ≥70 years (4%). SVR24 was achieved by 91% of patients (100% concordance with SVR12) and was similarly high in all subgroups, e.g. cirrhotic patients (90%), and in patients from mainland China (91%), Korea (94%) and Taiwan (87%). SVR24 was higher in patients without baseline NS5A (L31M/Y93H) resistance-associated variants (RAVs) (n=137/139 [99%]), regardless of the presence (98%) or absence (99%) of cirrhosis, and lower in patients with baseline NS5A RAVs (n=8/19 [42%]). All serious adverse events (AEs) (n=5/159 [3.1%]), grade 4 laboratory abnormalities (n=3/159 [1.9%]) and deaths (n=1/159 [0.6%]) that occurred on-treatment were unrelated to the study drugs; two patients discontinued due to AEs. Treatment was generally well tolerated regardless of cirrhosis status. Conclusions: Daclatasvir plus asunaprevir achieved a high SVR24 rate of 91%, rising to 99% in patients without baseline NS5A RAVs, and was generally well tolerated in cirrhotic and non-cirrhotic interferon (± ribavirin)-ineligible/intolerant patients with HCV genotype-1b infection from mainland China, Korea and Taiwan.

Oxidation Effect on the Break-Up of the Liquid Metal Jet

( Wei Hsiang Lai ),( Chia Chin Chen ) 한국액체미립화학회 2001 한국액체미립화학회 학술강연회 논문집 Vol.2001 No.-

Particle Size and Loading Effects on Particle-Laden Flow with Mono-sized Droplets

( Wei Hsiang Lai ),( Wei Fu Lu ),( Keh Chin Chang ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

Turbulence modulation is an interaction between phases that occurs in multiphase flow, and turbulence intensity traditionally can be represented as an indicator of turbulence modulation. Many researchers paid attention on the subject, but no coincident conclusion can be proposed. A general cognition is that larger particles induced wake to enhance the fluid turbulence intensity and smaller particles suppressed the fluid turbulence intensity since the fluid eddy imparted energy to the smaller particle. Here, the authors orderly changed particle size of dispersed phase and mass loading ratio (LR) to study the change on fluid turbulence intensity. Mono-dispersed droplets with a narrow size distribution were used to load into a homogeneous turbulence to investigate the turbulence modulation. Particle Dynamic Analyzer (PDA) was used to measure the particle (droplets and tracers) dynamic information. The particle concentration effect can be significantly observed. After coupling particle concentration and particle wetting area (πd2), a linear relationship can be obtained and it represents the turbulence modulation dominated the dilute two-phase flow as our expectation.

Home Energy Management System for Interconnecting and Sensing of Electric Appliances

( Wei-ting Cho ),( Chin-feng Lai ),( Yueh-min Huang ),( Wei-tsong Lee ),( Sing-wei Huang ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.7

Due to the variety of household electric devices and different power consumption habits of consumers at present, general home energy management (HEM) systems suffer from the lack of dynamic identification of various household appliances and a unidirectional information display. This study presented a set of intelligent interconnection network systems for electric appliances, which can measure the power consumption of household appliances through a current sensing device based on OSGi platform. The system establishes the characteristics and categories of related electric appliances, and searches the corresponding cluster data and eliminates noise for recognition functionality and error detection mechanism of electric appliances by applying the clustering algorithm. The system also integrates household appliance control network services so as to control them according to users` power consumption plans or through mobile devices, thus realizing a bidirectional monitoring service. When the system detects an abnormal operating state, it can automatically shut off electric appliances to avoid accidents. In practical tests, the system reached a recognition rate of 95%, and could successfully control general household appliances through the ZigBee network.