993 resultados para Transportation Engineering
Resumo:
Past research has suggested that social engineering poses the most significant security risk. Recent studies have suggested that social networking sites (SNSs) are the most common source of social engineering attacks. The risk of social engineering attacks in SNSs is associated with the difficulty of making accurate judgments regarding source credibility in the virtual environment of SNSs. In this paper, we quantitatively investigate source credibility dimensions in terms of social engineering on Facebook, as well as the source characteristics that influence Facebook users to judge an attacker as credible, therefore making them susceptible to victimization. Moreover, in order to predict users’ susceptibility to social engineering victimization based on their demographics, we investigate the effectiveness of source characteristics on different demographic groups by measuring the consent intentions and behavior responses of users to social engineering requests using a role-play experiment.
Resumo:
Past research has suggested that social networking sites are the most common source for social engineering-based attacks. Persuasion research shows that people are more likely to obey and accept a message when the source’s presentation appears to be credible. However, many factors can impact the perceived credibility of a source, depending on its type and the characteristics of the environment. Our previous research showed that there are four dimensions of source credibility in terms of social engineering on Facebook: perceived sincerity, perceived competence, perceived attraction, and perceived worthiness. Because the dimensionalities of source credibility as well as their measurement scales can fluctuate from one type of source to another and from one type of context to another, our aim in this study includes validating the existence of those four dimensions toward the credibility of social engineering attackers on Facebook and developing a valid measurement scale for every dimension of them.
Resumo:
We describe a surprising cooperative adsorption process observed by scanning tunneling microscopy (STM) at the liquid−solid interface. The process involves the association of a threefold hydrogen-bonding unit, trimesic acid (TMA), with straight-chain aliphatic alcohols of varying length (from C7 to C30), which coadsorb on highly oriented pyrolytic graphite (HOPG) to form linear patterns. In certain cases, the known TMA “flower pattern” can coexist temporarily with the linear TMA−alcohol patterns, but it eventually disappears. Time-lapsed STM imaging shows that the evolution of the flower pattern is a classical ripening phenomenon. The periodicity of the linear TMA−alcohol patterns can be modulated by choosing alcohols with appropriate chain lengths, and the precise structure of the patterns depends on the parity of the carbon count in the alkyl chain. Interactions that lead to this odd−even effect are analyzed in detail. The molecular components of the patterns are achiral, yet their association by hydrogen bonding leads to the formation of enantiomeric domains on the surface. The interrelation of these domains and the observation of superperiodic structures (moiré patterns) are rationalized by considering interactions with the underlying graphite surface and within the two-dimensional crystal of the adsorbed molecules. Comparison of the observed two-dimensional structures with the three-dimensional crystal structures of TMA−alcohol complexes determined by X-ray crystallography helps reveal the mechanism of molecular association in these two-component systems.
Resumo:
This research establishes that the study of mobility and transportation is multi-disciplinary and highly complex, involving the diverse interplay between infrastructural and psychological factors. Coincidently, a new paradigm in personal mobility is developing. A new generation of mobility solutions is becoming widely available in the form of car and ride sharing services. These services build on the assumption that customers no longer need ownership of a product in order to benefit from it. With the emergence of this new paradigm, this paper presents a methodological review of current practises used by the wider research community. Therefore, this research piece aims to explore methodological approaches involved in the study the effect of community on an individual’s attitudes, perceptions and behaviours of future mobility solutions. The results of this review indicate that the majority of published literature uses quantitative methods as opposed to qualitative and even fewer studies have sought to understand the human factors in these new mobility solutions. This gap in knowledge is a valuable opportunity for design. Inherently qualitative and human focused, design research can fill this gap in knowledge by applying distinctly user-centred methods such as persona design, narrative storytelling, and in-depth observations to discover deeper human insights.
Resumo:
Online communities have fundamentally changed how humans connected and are now so common they are fundamental to the human experience. As the Internet developed for Web 1.0 to Web 2.0, the functionality of these communities has far exceeded initial expectations. These communities have shifted from simply places to share information to ways to access products and services that bridge the online and offline worlds. This shift has led to the disruption of many industries with the transportation industry being one such sector. Both private transport providers and public transport systems face competition from online communities who are able to link services providers and customers more effectively and innovatively. These types of communities fall under what has been popularised as collaborative consumption or the sharing economy. The aim of this study is to explore the role of Design-led Innovation in the creation of digital futures, specifically online connected communities for successful new mobility solutions. To explore this proposition multiple data collection methods are proposed;Content Analysis, ii) A Comparative Qualitative Study consisting of Qualitative Interviews and Focus Groups / Design Workshops and iii) An Action Research Cycle of Embedded Practice. The multidisciplinary nature of this study grounds this research in a novel position contributing to new knowledge in both the field of design, and also a deeper understanding of the larger fast-growing online community phenomena.
Resumo:
This study examines and quantifies the effect of adding polyelectrolytes to cellulose nanofibre suspensions on the gel point of cellulose nanofibre suspensions, which is the lowest solids concentration at which the suspension forms a continuous network. The lower the gel point, the faster the drainage time to produce a sheet and the higher the porosity of the final sheet formed. Two new techniques were designed to measure the dynamic compressibility and the drainability of nanocellulose–polyelectrolyte suspensions. We developed a master curve which showed that the independent variable controlling the behaviour of nanocellulose suspensions and its composite is the structure of the flocculated suspension which is best quantified as the gel point. This was independent of the type of polyelectrolyte used. At an addition level of 2 mg/g of nanofibre, a reduction in gel point over 50 % was achieved using either a high molecular weight (13 MDa) linear cationic polyacrylamide (CPAM, 40 % charge), a dendrimer polyethylenimine of high molecular weight of 750,000 Da (HPEI) or even a low molecular weight of 2000 Da (LPEI). There was no significant difference in the minimum gel point achieved, despite the difference in polyelectrolyte morphology and molecular weight. In this paper, we show that the gel point controls the flow through the fibre suspension, even when comparing fibre suspensions with solids content above the gel point. A lower gel point makes it easier for water to drain through the fibre network,reducing the pressure required to achieve a given dewatering rate and reducing the filtering time required to form a wet laid sheet. We further show that the lower gel point partially controls the structure of the wet laid sheet after it is dried. Halving the gel point increased the air permeability of the dry sheet by 37, 46 and 25 %, when using CPAM, HPEI and LPEI, respectively. The resistance to liquid flow was reduced by 74 and 90 %, when using CPAM and LPEI. Analysing the paper formed shows that sheet forming process and final sheet properties can be engineered and controlled by adding polyelectrolytes to the nanofibre suspension.
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This doctoral studies focused on the development of new materials for efficient use of solar energy for environmental applications. The research investigated the engineering of the band gap of semiconductor materials to design and optimise visible-light-sensitive photocatalysts. Experimental studies have been combined with computational simulation in order to develop predictive tools for a systematic understanding and design on the crystal and energy band structures of multi-component metal oxides.
Resumo:
Three aspects of crystal engineering in molecular crystals are presented to emphasize the role of intermolecular interactions and factors influencing crystal packing. Hydrogen bonded tartrate-amine complexes have been analyzed with the propensity for formation of multidirectional hydrogen bonding as a key design element in the generation of materials for second harmonic generation (SHG). The invariance of the framework in DBT and its possible implications on SHG is outlined. The role of Fluorine in orienting molecules of coumarins, styrylcoumarins and butadienes for photodimerization is described with particular emphasis on its steering capability. Usage of coumarin as an design element for the generation of polymorphs of substituted styrylcoumarins is examined with specific examples.
Resumo:
The Government of Bangladesh is planning to develop and implement Bus Rapid Transit (BRT) in Dhaka city. This paper presents a stated choice survey conducted to understand workers’ attitudes toward BRT in Dhaka. The survey data are analysed using a multinomial logit (MNL) model to scrutinize social and economic factors’ impact on participant’s mode choices. Analysis results reveal that males, workers of higher age, education qualification, and income have a greater tendency towards choosing BRT.
Resumo:
Cooperative Intelligent Transportation Systems (C-ITS) allow in-vehicle systems, and ultimately the driver, to enhance their awareness of their surroundings by enabling communication between vehicles and road infrastructure. C-ITS are widely considered as the next major step in driving assistance systems, aiming at increasing safety, comfort and mobility for drivers. However, any communicating systems are subjected to security threats. A key component for providing secure communications at a large scale is a Public Key Infrastructure (PKI). Due to the safety-critical nature of Vehicle-to-Vehicle (V2V) communications, a C-ITS PKI has functional, performance and scalability requirements that differ from traditional non-automotive environments. This paper identifies and defines the key functional and security requirements for C-ITS PKI systems and analyses proposed C-ITS PKI standards against these requirements. In particular, the proposed US and European C-ITS PKI systems are identified as being too complex and not scalable. The paper also highlights various privacy, security and scalability concerns that should be considered for a secure C-ITS PKI solution in the Australian transport landscape.
Resumo:
This article focusses upon multi-modal transportation systems (MMTS) and the issues surrounding the determination of system capacity. For that purpose a multi-objective framework is advocated that integrates all the different modes and many different competing capacity objectives. This framework is analytical in nature and facilitates a variety of capacity querying and capacity expansion planning.
Resumo:
In this paper an attempt has been made to evaluate the spatial variability of the depth of weathered and engineering bedrock in Bangalore, south India using Multichannel Analysis of Surface Wave (MASW) survey. One-dimensional MASW survey has been carried out at 58 locations and shear-wave velocities are measured. Using velocity profiles, the depth of weathered rock and engineering rock surface levels has been determined. Based on the literature, shear-wave velocity of 330 ± 30 m/s for weathered rock or soft rock and 760 ± 60 m/s for engineering rock or hard rock has been considered. Depths corresponding to these velocity ranges are evaluated with respect to ground contour levels and top surface levels have been mapped with an interpolation technique using natural neighborhood. The depth of weathered rock varies from 1 m to about 21 m. In 58 testing locations, only 42 locations reached the depths which have a shear-wave velocity of more than 760 ± 60 m/s. The depth of engineering rock is evaluated from these data and it varies from 1 m to about 50 m. Further, these rock depths have been compared with a subsurface profile obtained from a two-dimensional (2-D) MASW survey at 20 locations and a few selected available bore logs from the deep geotechnical boreholes.
Resumo:
A pseudo-dynamical approach for a class of inverse problems involving static measurements is proposed and explored. Following linearization of the minimizing functional associated with the underlying optimization problem, the new strategy results in a system of linearized ordinary differential equations (ODEs) whose steady-state solutions yield the desired reconstruction. We consider some explicit and implicit schemes for integrating the ODEs and thus establish a deterministic reconstruction strategy without an explicit use of regularization. A stochastic reconstruction strategy is then developed making use of an ensemble Kalman filter wherein these ODEs serve as the measurement model. Finally, we assess the numerical efficacy of the developed tools against a few linear and nonlinear inverse problems of engineering interest.
Resumo:
Extracellular matrix (ECM) materials are widely used in cartilage tissue engineering. However, the current ECM materials are unsatisfactory for clinical practice as most of them are derived from allogenous or xenogenous tissue. This study was designed to develop a novel autologous ECM scaffold for cartilage tissue engineering. The autologous bone marrow mesenchymal stem cell-derived ECM (aBMSC-dECM) membrane was collected and fabricated into a three-dimensional porous scaffold via cross-linking and freeze-drying techniques. Articular chondrocytes were seeded into the aBMSC-dECM scaffold and atelocollagen scaffold, respectively. An in vitro culture and an in vivo implantation in nude mice model were performed to evaluate the influence on engineered cartilage. The current results showed that the aBMSC-dECM scaffold had a good microstructure and biocompatibility. After 4 weeks in vitro culture, the engineered cartilage in the aBMSC-dECM scaffold group formed thicker cartilage tissue with more homogeneous structure and higher expressions of cartilaginous gene and protein compared with the atelocollagen scaffold group. Furthermore, the engineered cartilage based on the aBMSC-dECM scaffold showed better cartilage formation in terms of volume and homogeneity, cartilage matrix content, and compressive modulus after 3 weeks in vivo implantation. These results indicated that the aBMSC-dECM scaffold could be a successful novel candidate scaffold for cartilage tissue engineering.
Resumo:
Effective processing of powdered particles can facilitate powder handling and result in better drug product performance, which is of great importance in the pharmaceutical industry where the majority of active pharmaceutical ingredients (APIs) are delivered as solid dosage forms. The purpose of this work was to develop a new ultrasound-assisted method for particle surface modification and thin-coating of pharmaceutical powders. The ultrasound was used to produce an aqueous mist with or without a coating agent. By using the proposed technique, it was possible to decrease the interparticular interactions and improve rheological properties of poorly-flowing water-soluble powders by aqueous smoothing of the rough surfaces of irregular particles. In turn, hydrophilic polymer thin-coating of a hydrophobic substance diminished the triboelectrostatic charge transfer and improved the flowability of highly cohesive powder. To determine the coating efficiency of the technique, the bioactive molecule β-galactosidase was layered onto the surface of powdered lactose particles. Enzyme-treated materials were analysed by assaying the quantity of the reaction product generated during enzymatic cleavage of the milk sugar. A near-linear increase in the thickness of the drug layer was obtained during progressive treatment. Using the enzyme coating procedure, it was confirmed that the ultrasound-assisted technique is suitable for processing labile protein materials. In addition, this pre-treatment of milk sugar could be used to improve utilization of lactose-containing formulations for populations suffering from severe lactose intolerance. Furthermore, the applicability of the thin-coating technique for improving homogeneity of low-dose solid dosage forms was shown. The carrier particles coated with API gave rise to uniform distribution of the drug within the powder. The mixture remained homogeneous during further tabletting, whereas the reference physical powder mixture was subject to segregation. In conclusion, ultrasound-assisted surface engineering of pharmaceutical powders can be effective technology for improving formulation and performance of solid dosage forms such as dry powder inhalers (DPI) and direct compression products.