142 research outputs found

    Analysis of Clickstream Data

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    This thesis is concerned with providing further statistical development in the area of web usage analysis to explore web browsing behaviour patterns. We received two data sources: web log files and operational data files for the websites, which contained information on online purchases. There are many research question regarding web browsing behaviour. Specifically, we focused on the depth-of-visit metric and implemented an exploratory analysis of this feature using clickstream data. Due to the large volume of data available in this context, we chose to present effect size measures along with all statistical analysis of data. We introduced two new robust measures of effect size for two-sample comparison studies for Non-normal situations, specifically where the difference of two populations is due to the shape parameter. The proposed effect sizes perform adequately for non-normal data, as well as when two distributions differ from shape parameters. We will focus on conversion analysis, to investigate the causal relationship between the general clickstream information and online purchasing using a logistic regression approach. The aim is to find a classifier by assigning the probability of the event of online shopping in an e-commerce website. We also develop the application of a mixture of hidden Markov models (MixHMM) to model web browsing behaviour using sequences of web pages viewed by users of an e-commerce website. The mixture of hidden Markov model will be performed in the Bayesian context using Gibbs sampling. We address the slow mixing problem of using Gibbs sampling in high dimensional models, and use the over-relaxed Gibbs sampling, as well as forward-backward EM algorithm to obtain an adequate sample of the posterior distributions of the parameters. The MixHMM provides an advantage of clustering users based on their browsing behaviour, and also gives an automatic classification of web pages based on the probability of observing web page by visitors in the website

    Dynamic Response of a Pendulum Isolator System under Vertical and Horizontal Earthquake Excitation

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    The paper studies a pendulum isolator. This isolator has a spherical surface which is placed on the foundation and it has an arm which is connected to the column of the building as a hinge. When the height of the arm is less than the curvature radius of the spherical surface, and a small movement is applied on it, a restoring force will be applied to the isolator. In this paper the eect of horizontal and vertical component of seismic load was studied. The dynamic equation of motion was obtained for the pendulum isolator under horizontal and vertical accelerations of seismic loads. The equation was solved by step time integration method. The comparison of the results of horizontal component eect and the combined eect of horizontal and vertical components on the isolator showed that the vertical component eect increased the isolator horizontal displacement response and increased the isolator horizontal acceleration.

    Protecting infrastructure networks from disinformation

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    Massive amount of information shared on online platforms makes the verification of contents time-consuming. Concern arises when the misleading or false information, called "disinformation", is exposed to many online platform users who have potential to react on it. The spread of disinformation can cause malicious consequences such as damage to critical infrastructure networks such as electric power, gas, and water distribution networks. Imagine a fake electricity discount, shared by disinformation campaigns, is exposed to many users on Twitter encouraging them to shift their electricity usage to a specific peak hour. If the population of users who engage with the fake discount exceeds a threshold, a blackout can happen due to the overconsumption of electricity. Thus, users access and exposure to accurate information on time can reinforce the infrastructures which are backbone of well-being for societies and economic growth. In this dissertation, we propose solutions to protect infrastructure networks from disinformation campaigns. The solutions include: (i) an integrated epidemiological-optimization (EPO) model involving a mixed integer linear programming model (MIP) and SIR (Susceptible, Infected, Recovered) model to protect physical infrastructure networks by counter disinformation (accurate information) spread in information networks, (ii) a disinformation interdiction model to influence physical infrastructure commodity consumers with accurate information given the topology of social network, (ii) a robust mixed integer linear programming model to propose solutions superior to the original EPO model under uncertain spread of disinformation scenarios. We illustrate our proposed models with two different case studies: (i) a sub-network of the western US interconnection power grid located in Los Angeles County in California, and (ii) the New York City subway system

    An assessment of haematological and serum biochemical indices in Salmo trutta caspius

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    Haematological and biochemical serum analyses were carried out in 131 fish specimens in three age and size groups including smolt, juvenile and breeder. Of these groups, smolt fish were 40 specimens in the average total length range 195.45±12.426mm and had an average weight of 84±15.5g, juvenile fish were 25 individuals and their average total length and weight were 267±20.877mm and 217.20±22.013g, respectively. The 41 breeder fish had an average total length of 578.24±68.487mm and an average weight of 1994.2±775.379g. Another 25 breeder fish were also sampled in the spawning season for blood biochemical analyses had an average total length range of 617±59.9mm and weighed on average 2227.5±647.5g each. Red blood cell counts were 866600 per mm super(3) and 1259400 per mm ^(3) in smolt and breeder fish respectively. The average hematocrit was 48.39% in smolt and 44.29% in breeder fish. The average hemoglobin was 8.85g/dl in smolt and 10.91g/dl in breeder fish. White blood cell count was 8781.58 per mm ^(3) in smolt and 5217.65 per mm ^(3) in breeder fish. Other measurements were as follows: Lymphocyte 90.57% in smolt and 73.22% in breeders, Neutrophil 5.12% in smolt and 16.92% in breeders, Monocyte 1.27% in smolt and 4.24% in breeders, and clotting time was 282.34 seconds in smolt and 291.47 seconds in breeder fish. We also measured MCV, MCH and MCHC in smolt and breeder fish along with biochemical parameters. The glucose level was 2.97mmol/1 in juvenile and 1.99mmol/1 in breeder fish. The cholesterol level was 4.26mmol/l in juvenile and 7.06mmol/1 in breeders. The triglyceride amount was 2.35mmol/l in juvenile and 2.47mmol/l in breeder specimens and the calcium level was 2.44 in juvenile and 2.61 mmol/1 in breeder fish

    Comparison of produced fish protein hydrolysate from viscera and head of silver carp (Hypophthalmichthys molitrix) using alcalase enzyme and internal tissue enzymes

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    In the present study, hydrolysed protein of viscera and head of Silver carp (Hypophthalmichthys molitrix) was compared using Alcalase enzyme and internal tissue enzymes at 2 and 4 hours. The result indicated that product by Alcalase (Treatment 1) had significantly higher protein and rate of hydrolysates than that produced by internal tissue enzymes (Treatment 2). So, the highest mean (±SD) protein (68.10±1.33) was related to treatment 1-head (with Alcalase enzyme) after 4 hours and the highest rate of hydrolysates (29.36±1.35) was related to treatment 1-head (with Alcalase enzyme) after 4 hours. The result indicated that rate of hydrolysates raised as time of hydrolysates increased. However the intensity and rate of hydrolysates is reduced. The highest rate of hydrolysates occurred at 120 minutes in the first. This mode was similar for two treatments. The result can be considered as the Alcalase was preferred to internal enzyme

    Study on some hematological factors of Salmo trutta caspius

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    Regarding to measure some hematological factors of Caspian Salmon (Salmo Trutta caspius), 55 immature and 21 mature individuals were studied. The main results were: Immature Mature - Hemoglobin value (gr/dl) 7.20 9.87 - Hematocrit 34.1 39.2 - Mean No. of red blood cells (per mm3) 934300 1306200 - Mean No. of white blood (per mm3) 8380 6219 - Mean No. of platelets (per mm3) 21180 13159 As the results showed the number of white blood cells and platelets in immature individuals were more than mature specimen. The obtained results of blood indices were as follow: Immature Mature - Mean MCV (FL) 385.4 302.9 - Mean MCH (Pg) 82.0 75.5 - Mean MCHC (%) 21.6 25.6 - Lymphocyte (%) 96.1 69.9 - Neutrophil (%) 3.4 29.4 - Monocyte (%) 0.52 1.14 Notice: Eosinophil and basophil cells weren't observed

    Novel electronic adherence monitoring devices in children with asthma: a mixed-methods study

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    Introduction: Adherence monitoring to inhaled corticosteroids is an essential component of asthma management. Electronic monitoring devices (EMD) provide objective data on date, time and number of actuations. However, most give no information on inhalation. Novel EMD (NEMD) platforms have the potential to monitor both activation and inhalation. Aim: To assess the feasibility of NEMDs, in terms of usability, acceptability to patients and healthcare professionals and accuracy. Methods: This was an open-label, prospective, mixedmethods, pragmatic randomised study. Children with asthma attending specialist tertiary care were randomised to one of four NEMD: Remote Directly Observed Therapy (R-DOT), Hailie Smartinhaler, INhaler Compliance Assessment device (INCA) and the Rafi-tone App. Following monitoring, participants were invited to focus groups or one-to-one interviews. Usability and acceptability were evaluated using themes identified from the focus groups and interviews. Adherence accuracy was determined using adherence data from each NEMD. Results: Thirty-five children were recruited; 18 (51%), (11 males, median age 13.5 (7–16) years) completed monitoring, 14 (78%) provided feedback. Participants identified various features such as ease of use and minimal effort as desirable criteria for an NEMD. The Hailie and INCA fulfilled these criteria and were able to record both actuation and inhalation. Negative themes included a ‘Big Brother’ effect and costs. Conclusion: There was no ‘one size fits all’, as participants identified advantages and disadvantages for each NEMD. Devices that can easily calculate adherence to activation and inhalation have the potential to have greatest utility in clinical practice. Each NEMD has different functionality and therefore choice of platform should be determined by the needs of the patient and healthcare professional

    Collocation method based on modified ‎cubic‎ B-spline ‎for option pricing ‎models

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    Collocation‎‎ ‎method ‎based ‎on ‎modified‎ cubic B-spline functions ‎has ‎been ‎developed‎ ‎for ‎the ‎valuation ‎‎‎of European‎, ‎American and Barrier options of single ‎asset. ‎The ‎new ‎approach ‎contains ‎‎discretizing ‎of‎ t‎‎emporal ‎derivative‎ ‎using ‎finite ‎difference ‎approximations ‎and ‎approximating‎ the option price with the ‎modified‎ B-spline functions‎. ‎Stability of this method has been discussed and shown that it is unconditionally stable‎. ‎The ‎efficiency ‎of ‎the‎ ‎proposed ‎method ‎is ‎tested ‎by ‎different ‎examples‎‎‎.

    Identifying dimensions and indicators of personal knowledge management Indicators in Regional Water Company of Fars

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    Objective: This research identified dimensions and Indicators of personal knowledge management and presented an Interpretative Structural Model of Indicators affecting personal knowledge management in the Regional Water Company of Fars. Methodology: This study is practical in terms of type and purpose and descriptive-analytical in terms of data collection method, which has been done with a quantitative approach. Data collection tools are checklists and factor matrices. The statistical population of this study includes all employees of Regional Water Company of Fars in 1400 (350 people). That by Using of purposive sampling method, 25 knowledge management experts were selected as the statistical sample of the research. Findings: According to Penetration power model and the degree of dependence identified among the Indicators studied in this study, Indicators of "scientific activities to achieve solutions to specific issues or problems in the Scientific field ", "Scientific activities for inventing new laboratory methods", "Patent or scientific discovery based on scientific activities", "Storage and classification of important and required files and folders", "Book Publishing (Compilation)", and "Publication of a scientific research article" are the most effective indicators of personal knowledge management among the employees of Regional Water Company of Fars. Originality: Identifying the Penetration power model and the degree of dependence on indicators of tacit knowledge management causes organizations to identify their strengths and weaknesses to improve the flow of knowledge inside and outside of their organization. This research is conducted for the first time in Regional Water Company of Fars
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