Integrating Shared Mobility Services with Transit Could Produce Economic and Environmental Benefits

This research brief summarizes the findings from the associated study, which examined the potential to improve transportation system efficiency by reevaluating and redefining the role of public transit and its design principles in the new context of technology and shared mobility. Specifically, it evaluated the financial feasibility of an integrative, multimodal transportation system where public and private mobility services coexist to maximize economic and environmental benefits and free up public transit resources to be reallocated more efficiently

Optimization of traffic safety facilities in highway tunnels based on driver’s visual perception

This paper delves into the optimization of traffic safety facilities within highway tunnels by leveraging the inherent visual perception characteristics of drivers. Grounded in the context of Zhejiang Province’s highway construction, the study draws from practical insights provided by highway tunnel projects within the region. Through a meticulous blend of on-site investigations and empirical experimentation, the research assesses the effectiveness of existing safety installations in highway tunnels. The analysis extends to the exploration of optimizing the design and placement of traffic safety facilities, informed by the distinct visual perception tendencies exhibited by drivers. By amalgamating the insights derived from driver perception and real-world highway tunnel dynamics, the paper proposes a refined and contextually attuned approach to enhancing traffic safety measures. This study not only contributes to the field of transportation engineering but also holds the potential to significantly enhance the overall safety of highway tunnel environments

Electron impact ionization and multiphoton ionization of doped superfluid helium droplets: A comparison

We compare characteristics of electron impact ionization (EI) and multiphoton ionization (MPI) of doped super fluid helium droplets using the same droplet source. Selected dopant ion fragments from the two ionization schemes demonstrate different dependence on the doping pressure, which could be attributed to the different ionization mechanisms. While EI directly ionizes helium atoms in a droplet therefore has higher yields for bigger droplets (within a limited size range), MPI is insensitive to the helium in a droplet and is only dependent on the number of dopant molecules. The optimal timing of the ionization pulse also varies with the doping pressure, implying a velocity slip among different sized droplets. Calculations of the doping statistics and ionization probabilities qualitatively agree with the experimental data. Our results offer a word of caution in interpreting the pressure and timing dependence of super fluid helium droplets, and we also devise a scheme in achieving a high degree of doping while limiting the contribution of dopant clusters

Communication: Electron diffraction of ferrocene in superfluid helium droplets

We report electron diffraction of ferrocene doped in superfluid helium droplets. By taking advantage of the velocity slip in our pulsed droplet beam using a pulsed electron gun, and by doping with a high concentration of ferrocene delivered via a pulsed valve, we can obtain high quality diffraction images from singly doped droplets. Under the optimal doping conditions, 80% of the droplets sampled in the electron beam are doped with just one ferrocene molecule. Extension of this size selection method to dopant clusters has also been demonstrated. However, incomplete separation of dopant clusters might require deconvolution and modeling of the doping process. This method can be used for studies of nucleation processes in superfluid helium droplets

Electron Diffraction of Superfluid Helium Droplets

We present experimental results of electron diffraction of super fluid helium droplets and droplets doped with phthalocyanine gallium chloride, and discuss the possibility of performing the same experiment with a laser aligned sample. The diffraction profile of pure droplets demonstrates dependence on the nozzle temperature, i. e., on the average size of the droplets. Larger clusters demonstrate faster decay with increasing momentum transfer, while smaller clusters converge to isolated gas phase molecules at source temperatures of 18 K and higher. Electron diffraction of doped droplets shows similar modified molecular scattering intensity as that of the corresponding gas phase molecules. Based on fittings of the scattering profile, the number of remaining helium atoms of the doped droplets is estimated to be on the order of hundreds. This result offers guidance in assessing the possibility of electron diffraction from laser aligned molecules doped in superfluid helium droplets.Keywords: Coherent single molecule diffraction, Doped superfluid helium droplets, Electron diffraction, Superfluid helium droplets, Phthalocyanine gallium chloride, Gas phase electron diffractio

Facile time-of-flight methods for characterizing pulsed superfluid helium droplet beams

We present two facile time-of-flight (TOF) methods of detecting superfluid helium droplets and droplets with neutral dopants. Without an electron gun and with only a heated filament and pulsed electrodes, the electron impact ionization TOF mass spectrometer can resolve ionized helium clusters such as He₂ ⁺ and He₄ ⁺, which are signatures of superfluid helium droplets. Without ionizing any helium atoms, multiphoton non-resonant laser ionization of CCl₄ doped in superfluid helium droplets at 266 nm generates complex cluster ions of dopant fragments with helium atoms, including (He)[subscript]nC⁺, (He)[subscript]nCl⁺, and (He)[subscript]nCCl⁺. Using both methods, we have characterized our cryogenic pulsed valve—the Even-Lavie valve. We have observed a primary pulse with larger helium droplets traveling at a slower speed and a rebound pulse with smaller droplets at a faster speed. In addition, the pickup efficiency of dopant is higher for the primary pulse when the nozzle temperature is higher than 13 K, and the total time duration of the doped droplet pulse is only on the order of 20 μs. These results stress the importance of fast and easy characterization of the droplet beam for sensitive measurements such as electron diffraction of doped droplets.Article Copyright 2015 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Review of Scientific Instruments and may be found at http://scitation.aip.org/content/aip/journal/rs

eCommerce Consumer Behaviour in Southeast Asia

This master’s thesis aims to investigate e-commerce consumer behavior in Southeast Asia, with a focus on identifying online purchase behavior, assessing how different factors could influence online consumer’s perception about perceived risk and trust and proposing possible causes and reasons behind it. To fulfill these goals, the research is constituted of data mining, a quantitative survey and content analysis. The dataset contains half a million transaction records from 385 e-merchants in the ASEAN-6. Secondly, perceived risk and trust towards online shopping in Malaysia, Singapore, and the Philippines were examined by a survey method, with a sample of 124 post-adoption respondents. Lastly, Content analysis on the top 50 online stores in the ASEAN-6 (300 online stores in total) was conducted to study parity and differentiation in terms of service and function offerings. The analysis reveals that conversion rate, average order value, coupon usage and order distribution differs in countries, devices and time. Besides, a positive correlation between purchase intention and attitudes towards online shopping is detected. In contrast, there is a negative correlation between purchase intention and perceived risk. Lastly, recommendations are given to e-commerce companies in the region.This master’s thesis aims to investigate e-commerce consumer behavior in Southeast Asia, with a focus on identifying online purchase behavior, assessing how different factors could influence online consumer’s perception about perceived risk and trust and proposing possible causes and reasons behind it. To fulfill these goals, the research is constituted of data mining, a quantitative survey and content analysis. The dataset contains half a million transaction records from 385 e-merchants in the ASEAN-6. Secondly, perceived risk and trust towards online shopping in Malaysia, Singapore, and the Philippines were examined by a survey method, with a sample of 124 post-adoption respondents. Lastly, Content analysis on the top 50 online stores in the ASEAN-6 (300 online stores in total) was conducted to study parity and differentiation in terms of service and function offerings. The analysis reveals that conversion rate, average order value, coupon usage and order distribution differs in countries, devices and time. Besides, a positive correlation between purchase intention and attitudes towards online shopping is detected. In contrast, there is a negative correlation between purchase intention and perceived risk. Lastly, recommendations are given to e-commerce companies in the region

Coordinated Energy Storage for Resilient and Equitable Service of Electrical Vehicle Charging Infrastructure Systems under Climate Risks

The rapid growth of Electric Vehicle (EV) populations, driven by Zero-Emission Vehicle (ZEV) regulations across the United States, poses challenges to the EV charging infrastructures, including ensuring equitable recharging access, addressing affordability imbalances, and enhancing resilience against the ever-increasing power disruptions. Existing studies on those topics reveal critical gaps: lack of an evaluation framework that incorporates affordability and resilience considerations, limited effort on affordability challenges and lack of effective resilience planning. In light of these knowledge gaps, this dissertation seeks to 1) understand the potential equity issues in existing EV charging infrastructure systems considering multiple factors including affordability and resilience, and 2) develop a multi-agent modeling framework for Energy Storage Systems (ESS) integration planning that identifies strategies/policies for enhancing both affordability and resilience. For optimal resilience enhancement, this dissertation envisions a hybrid infrastructure layout that combines individually-owned ESSs by charging stations and independent ESSs collectively utilized by multiple stations, which are coordinated by independent operators. Case studies, built on counties within the region of the Sacramento Area Council of Governments, unfold in two parts. Part A evaluated existing infrastructures, revealing an uneven development of charging resources with respect to land use, with over 95% allocated in central and established communities. However, there seem to be minimal income-related inequity concerns associated with accessibility when factoring in demand and examining correlation with income. Notably, rural residential areas exhibit the highest resilience challenges. Part B explored optimal ESS layout, highlighting the significant role of ESS in reducing public EV charging cost, and revealing the considerable resilience value of coordinated ESS systems. For areas with a low demand-to-supply ratio and high risks of power crises, resilience regulations can significantly improve the system's defense against power disruptions. However, these regulations are less effective in areas with high demand-to-supply ratios. Moreover, they can increase costs for end users. By introducing additional incentives, resilience can be enhanced while simultaneously reducing user expenses, leading to a net decrease in societal costs