Web Usage Mining to Extract Knowledge for Modelling Users of Taiwan Travel Recommendation Mobile APP

This work presents the design of a web mining system to understand the navigational behavior of passengers in developed Taiwan travel recommendation mobile app that provides four main functions including recommend by location , hot topic , nearby scenic spots information , my favorite and 2650 scenic spots. To understand passenger navigational patterns, log data from actual cases of app were collected and analysed by web mining system. This system analysed 58981 sessions of 1326 users for the month of June, 2014. Sequential profiles for passenger navigational patterns were captured by applying sequence-based representation schemes in association with Markov models and enhanced K-mean clustering algorithms for sequence behavior mining cluster patterns. The navigational cycle, time, function numbers, and the depth and extent (range) of app were statistically analysed. The analysis results can be used improved the passengers\u27 acceptance of app and help generate potential personalization recommendations for achieving an intelligent travel recommendation service

POE Lubricant Candidates For Low GWP Refrigerants

Several series of polyol ester (POE) refrigeration lubricants have been investigated for low GWP refrigerant R32 (R-410A replacement) and HFO-1234ze (R-134a replacement). The main problem of R32/HFO refrigeration lubricant development can be summarized as balancing between miscibility, solubility and lubricity. Generally speaking, refrigerant-lubricant mixture with highly miscible property in low temperature evaporator will lead to more soluble phenomenon in high temperature compressor. Therefore, when refrigerant is well miscible with refrigeration lubricant, dissolved refrigerant will reduce working viscosity of refrigerant-oil mixture in compressor, and thus results in lower lubricity, wear of sliding parts, and compressor durability shortage. In our studies, the key factor which result in aforementioned phenomenon was found, and can be controlled independently by using optimized chemical structure. For R32 compressor system, we have successfully developed a series of POE refrigeration lubricant, with viscosities ranging from 32cSt to 90cSt at 40°C, and with a wide range of miscibility (20% oil) from -40℃ to 2℃. From results of PVT experiments and lubricity tests (Falex P/V and four ball), it demonstrated to be possible to develop a POE oil with high miscibility, low solubility and high working viscosity. All results in R32 system were better than traditional refrigeration lubricant in R410A system. Meanwhile, we also were able to identify the relationship between surface tension of chemical structure and lubricity. For HFO-1234ze compressor system, incumbent refrigeration lubricants suitable for R134a are almost fully miscible in HFO-1234ze, which could lead to severe refrigerant dilution of lubricant viscosity and poor lubricity due to high solubility. Through studies of chemical structure of refrigeration lubricants, reliable experimental tests and rigorous thermodynamic calculation, we created a range of POE lubricants (ISO68 to ISO220) with miscibility (20% oil) from -33℃ to -13℃, all the while, maintaining solubility and working viscosity on par with the common POE refrigeration lubricants currently used in R-134a system

The Influence of Lubricant in HFC & HFO Blend Refrigeration system

Although HFO refrigerants are considered the low GWP solutions to the global warming problem, some properties of HFO refrigerants prohibited the direct drop in replacement application in the refrigeration system. As a result, to replace the high GWP HFC refrigerants, HFC & HFO refrigerants are blended to combine their properties to become a workable solution. Both HFC and HFO refrigerants have similar basic properties; however, one of the HFO refrigerants properties is good miscibility to incumbent refrigeration lubricants, especially HFO-1234ze. Generally speaking, refrigerant-oil mixture with highly miscible property in low temperature evaporator will lead to more soluble phenomenon in high temperature compressor. Therefore, when refrigerant is well miscible with refrigeration oil, the dissolved refrigerant will reduce working viscosity of refrigerant-oil mixture in compressor, which could results in lower lubricity, increase wear of sliding parts, and shorter compressor durability. In our studies, we discuss the influence of lubricant in HFC & HFO blend refrigeration system, such as R513A or R450A. Compared to the lubricant performance in HFO refrigerants, the same lubricant in the HFC & HFO blend refrigerants do not lead to severe refrigerants dilution of lubricant viscosity, which causes poor lubricity due to high solubility. According to our previous study, we know the better miscibility brings the better solubility in R1234ze system. We also developed lubricants with different miscibility properties in HFC & HFO blend refrigerants in order to investigate the miscibility, solubility and lubricity performance in the HFC & HFO refrigeration systems

An efficient surrogate model for emulation and physics extraction of large eddy simulations

In the quest for advanced propulsion and power-generation systems, high-fidelity simulations are too computationally expensive to survey the desired design space, and a new design methodology is needed that combines engineering physics, computer simulations and statistical modeling. In this paper, we propose a new surrogate model that provides efficient prediction and uncertainty quantification of turbulent flows in swirl injectors with varying geometries, devices commonly used in many engineering applications. The novelty of the proposed method lies in the incorporation of known physical properties of the fluid flow as {simplifying assumptions} for the statistical model. In view of the massive simulation data at hand, which is on the order of hundreds of gigabytes, these assumptions allow for accurate flow predictions in around an hour of computation time. To contrast, existing flow emulators which forgo such simplications may require more computation time for training and prediction than is needed for conducting the simulation itself. Moreover, by accounting for coupling mechanisms between flow variables, the proposed model can jointly reduce prediction uncertainty and extract useful flow physics, which can then be used to guide further investigations.Comment: Submitted to JASA A&C

Customer Behavior Survery for Cultural and Creative Park in Taiwan

Cultural and Creative Park is a recreational campus which usually consists of exhibition, gallery, show room, movie theater, and multi-function facilities to provide the cultural activities. Besides, in the Cultural and Creative Park, restaurants, coffee shops, bookstores, gift shops, and other business units are nearby. How to improve the customer experience in the Cultural and Creative Park is an important research question for the managerial division to promote culture industries. In this research, the questionnaires were developed and performed in one of creative park in Taipei, Taiwan to study customer behavior. This paper addresses the survey result and the insights revealed from the survey