1,721,094 research outputs found
The influence of bus service satisfaction on university students' mode choice
No full textThe purpose of this study was to determine the relationship between bus service satisfaction and the transport mode of choice among university students in Qatar. The degree of bus service satisfaction was collected directly from questionnaire surveys, in which university students were asked questions in relation to their satisfaction with the bus service they used and their transport mode of choice. These questions were categorized into three factors according to confirmatory factor analysis: service at bus stops, service of busses, and service of drivers. Furthermore, the students were asked which mode of transport they used given the choice between public and private transport. This study presents a structural equation model to determine how much bus service satisfaction affects people's decisions about their transport mode. The results from the analysis showed that three key factors-namely, service at bus stops, service of busses, and service of bus drivers-were strongly correlated to the mode of choice. In particular, the bus stop was strongly associated with ease of use, shade, cleanliness, safety, and crowdedness level, while the bus itself influenced reliability, travel time, and frequency. Complying with traffic laws and the driver's attitude were also important contributors to the level of bus service satisfaction. Ultimately, this study will be beneficial for policy/decision-makers. It will allow them to determine what needs to be accomplished to encourage people to use public transportation.Scopu
Assessment of the taxi service in Doha
No full textThis research focuses on passengers' satisfaction of the taxi service in Doha, Qatar. Qatar is a rich developing country where taxis are widely considered as a public transportation service due to the limited use of the existing bus service and the profoundly dominant use of private car by expats and Qatari locals. The main objective of this research is to identify the quality attributes of the current taxi service. A descriptive analysis relating the demographic, accessibility, and trip purposes to taxi users in general in Doha with overall service satisfaction was conducted. A Structural Equation Model was used to assess the taxi service attributes that influence the users' perceived satisfaction. Two models were developed: one was a relationship between the demographic and satisfaction of the users while the other was between the trip time and the satisfaction of the users. The first model supports the premise that income is the greatest attribute in the demographic followed by marital status, age, and occupation. On the other hand, the latter model demonstrated that waiting time is the most contributing variable among the times spent by taxi users followed by walking from work to a station, journey time, and walking from home to a station. 2016 Elsevier Ltd.Scopu
Comparison of SimTraffic and VISSIM Microscopic Traffic Simulation Tools in Modeling Roundabouts
Full text linkAbstract SimTraffic and VISSIM are two microscopic traffic simulation tools that are capable of modeling arterial roads with signalized intersections and roundabouts. This study compares the performance of the two simulation tools in modeling dual lane and triple lane roundabouts under different scenarios such as traffic volume, proportion of left turning movement, and proportion of trucks in the traffic flow. The two simulation tools did not show statistically significant difference in general. However; in the case of high traffic volumes, VISSIM showed higher average delays than those from SimTraffic compared to nearly identical results in the case of low traffic volumes
Traffic safety at road-rail level crossings using a driving simulator and traffic simulation
No full textSeveral intelligent transportation systems (ITS) were used with an advanced driving simulator to assess its influence on driving behavior. Three types of ITS interventions were tested: video in vehicle, audio in vehicle, and on-road flashing marker. The results from the driving simulator were inputs for a developed model that used traffic microsimulation (VISSIM 5.4) to assess the safety interventions. Using a driving simulator, 58 participants were required to drive through active and passive crossings with and without an ITS device and in the presence or absence of an approaching train. The effect of changes in driver speed and compliance rate was greater at passive crossings than at active crossings. The slight difference in speed of drivers approaching ITS devices indicated that ITS helped drivers encounter crossings in a safer way. Since the traffic simulation was not able to replicate a dynamic speed change or a probability of stopping that varied depending on ITS safety devices, some modifications were made to the traffic simulation. The results showed that exposure to ITS devices at active crossings did not influence drivers’ behavior significantly according to the traffic performance indicator, such as delay time, number of stops, speed, and stopped delay. However, the results of traffic simulation for passive crossings, where low traffic volumes and low train headway normally occur, showed that ITS devices improved overall traffic performance
IDENTIFICATION, ISOLATION AND OPTIMIZATION OF ANTIFUNGAL METABOLITES FROM THE STREPTOMYCES MALACHITOFUSCUS CTF9
No full textAn indigenous Streptomyces isolate CTF9, exhibiting promising antifungal activity against Mucor miehei and Candida albicans in pre-screening studies, was investigated by cultivation in a 50-L fermenter and by subsequent isolation, purification, and structure elucidation of the active metabolites. Based on the morphological, biochemical, and physiological characterization, as well as the 16S rRNA gene sequence, the isolate CTF9 was identified as Streptomyces malachitofuscus. Using a series of chromatographic techniques, two pure compounds were isolated from the obtained extracts after the fermentation of the isolate CTF9. The isolated compounds were identified as phenylacetic acid and indolyl-3-lactic acid by mass spectrometry (MS) and NMR analysis. The culture optimization studies revealed that the isolate CTF9 can use a variety of low-cost carbon and nitrogen sources to generate the maximum quantity of industrially important metabolites at an elevated temperature of 35 degrees C and at a pH 7.8.Higher Education Commission (HEC) of Pakista
Revealing the hidden features in traffic prediction via entity embedding
No full textModels based on neural networks (NN) have been used widely and successfully in traffic prediction resulting in improved accuracy and efficiency in traffic flow, speed, passenger flow, and delay. Input data include continuous and discrete variables and these impact traffic changes both internally and externally. However, few studies have focused on discrete traffic-related variables in NN-based forecasting models. Inappropriate utilization of discrete variables may cause useful factors to become insignificant and lead to an inefficient forecasting model. In this paper, a NN-based model is used to predict traffic flow of a bike-sharing system in Suzhou, China. The model only uses external and discrete variables like weather, places of interest (POIs), and holiday periods. We applied both entity embedding and one-hot encoding for the data preprocessing of these variables. The results show that (1) Entity embedding can effectively increase the continuity of categorical variables and slightly improve the prediction efficiency for the NN model; and (2) The hidden relationship in variables can be identified through visual analysis, and the trained embedding vectors can also be used in traffic-related tasks.
Two anthraquinone compounds from a marine actinomycete isolate M097 isolated from Jiaozhou Bay
No full textTwo anthraquinone compounds were isolated from the culture broth of a marine actinomycete isolate M097. The structures were elucidated as Aloesaponarin II and 1,6-dihydroxy-8-hydroxymethyl-anthraquinone by detailed interpretation of their spectra. It is the first time that the latter has ever been reported as a secondary metabolite from a wild-type strain. The results showed that the actinomycete isolate M097 could be a promising material for studying the biosynthetic pathway of polyketides and the production of novel recombinant polyketides
PURIFICATION AND IDENTIFICATION OF BIOACTIVE ANGUCYCLINONES FROM Streptomyces matensis BG5, ISOLATED FROM THE RHIZOSPHERE OF Rosa indica L.
No full textA newly isolated strain Streptomyces sp. BG5 was investigated for the production of bioactive compounds. The strain exhibited broad-spectrum activity against an array of nine test organisms including gram-positive bacteria, gram-negative bacteria, and fungal and microalgal pathogens, along with a moderate cytotoxic response (28.9% mortality) in a microwell cytotoxicity assay against the brine shrimp Artimia salina. The morphological, physiological, and biochemical characterization of the Streptomyces sp. BG5 strongly suggested it to be a member of the genus Streptomyces. The nucleotide sequence of 16S rRNA gene (1433 pb) of the Streptomyces sp. BG5 (Gene bank accession number EU301836) exhibited high similarity (98%) with Streptomyces matensis. The large-scale fermentation of Streptomyces sp. BG5 and subsequent extraction, isolation, and purification of the crude extract afforded three pure compounds. The structures of these compounds were identified as ochromycinone (1a), emycin D (2), and 1-acetyl-beta-carbolin (3), based on nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry, and by comparison with reference data from the literature. Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.Higher Education Commission (HEC) of Pakistan under IRSI
IDENTIFICATION, ISOLATION AND OPTIMIZATION OF ANTIFUNGAL METABOLITES FROM THE STREPTOMYCES MALACHITOFUSCUS CTF9
No full textAn indigenous Streptomyces isolate CTF9, exhibiting promising antifungal activity against Mucor miehei and Candida albicans in pre-screening studies, was investigated by cultivation in a 50-L fermenter and by subsequent isolation, purification, and structure elucidation of the active metabolites. Based on the morphological, biochemical, and physiological characterization, as well as the 16S rRNA gene sequence, the isolate CTF9 was identified as Streptomyces malachitofuscus. Using a series of chromatographic techniques, two pure compounds were isolated from the obtained extracts after the fermentation of the isolate CTF9. The isolated compounds were identified as phenylacetic acid and indolyl-3-lactic acid by mass spectrometry (MS) and NMR analysis. The culture optimization studies revealed that the isolate CTF9 can use a variety of low-cost carbon and nitrogen sources to generate the maximum quantity of industrially important metabolites at an elevated temperature of 35 degrees C and at a pH 7.8.Higher Education Commission (HEC) of Pakista
Reveal the hidden layer via entity embedding in traffic prediction
No full textThe neural network-based models have been widely used in traffic prediction. They have improved accuracy and efficiency in traffic flow, speed, passenger flow, and delay. Many variables are considered to predict traffic indicators and good techniques for choosing the most influenced variables to results have been developed. Since the neural network models treat independent variables as continuous variables, there are few studies on the use of categorical variables. In addition, the neural network has been criticized as the internal relationships of hidden layers are generally unknown. This paper investigates neural networks to predict the use of bike-sharing systems in Suzhou, China considering a large amount of categorical data. Two methods here, Entity embedding and one-hot encoding are applied. The comparison experiments verify that the entity embedding method is more efficient than one-hot encoding. Furthermore, the hidden layers are visually analyzed by t-SNE, and the relationships with time, weather, surroundings and other variables for the traffic volume at shared bike sites are discussed. The research results show that: 1. Entity embedding can effectively increase the continuity of categorical variables and therefore, improve the prediction efficiency for the neural network models. 2. The relationship between variables can be identified through visual analysis, and the trained embedding vectors can also be used to supervise clustering. - 2019 The Authors. Published by Elsevier B.V.Scopu
- …
