A virtual odometer for a Quadrotor Micro Aerial Vehicle

This paper describes the synthesis and evaluation of a "virtual odometer" for a Quadrotor Micro Aerial Vehicle. Availability of a velocity estimate has the potential to enhance the accuracy of mapping, estimation and control algorithms used with quadrotors, increasing the effectiveness of their applications. As a result of the unique dynamic characteristics of the quadrotor, a dual axis accelerometer mounted parallel to the propeller plane provides measurements that are directly proportional to vehicle velocities in that plane. Exploiting this insight, we encapsulate quadrotor dynamic equations which relate acceleration, attitude and the aerodynamic propeller drag in an extended Kalman filter framework for the purpose of state estimation. The result is a drift free estimation of lateral and longitudinal components of translational velocity and roll and pitch components of attitude of the quadrotor. Real world data sets gathered from two different quadrotor platforms, together with ground truth data from a Vicon system, are used to evaluate the effectiveness of the proposed algorithm and demonstrate that drift free estimates for the velocity and attitude can be obtained

Calibration of a Rotating Laser Range Finder using Intensity Features

© 2018 IEEE. This paper presents an algorithm for calibrating a '3D range sensor' constructed using a two-dimensional laser range finder (LRF), that is rotated about an axis using a motor to obtain a three-dimensional point cloud. The sensor assembly is modelled as a two degree of freedom open kinematic chain, with one joint corresponding to the axis of the internal mirror in the LRF and the other joint set along the axis of the motor used to rotate the body of the LRF. In the application described in this paper, the sensor unit is mounted on a robot arm used for infrastructure inspection. The objective of the calibration process is to obtain the coordinate transform required to compute the locations of the 3D points with respect to the robot coordinate frame. Proposed strategy uses observations of a set of markers arbitrarily placed in the environment. Distances between these markers are measured and a metric multidimensional scaling is used to obtain the coordinates of the markers with respect to a local coordinate frame. Intensity associated with each beam point of a laser scan is used to locate the reflective markers in the 3D point cloud and a least squares problem is formulated to compute the relationship between the robot coordinate frame, LRF coordinate frame and the marker coordinate frame. Results from experiments using the robot, LRF combination to map a cavity inside a steel bridge structure are presented to demonstrate the effectiveness of the calibration process

Customer Behavior Analysis for Social Media

It is essential for a business organization to get the customer feedback in order to grow as a company. Business organizations are collecting customer feedback using various methods. But the question is ‘are they efficient and effective?' In the current context, there is more of a customer oriented market and all the business organizations are competing to achieve customer delight through their products and services. Social Media plays a huge role in one's life. Customers tend to reveal their true opinion about certain brands on social media rather than giving routine feedback to the producers or sellers. Because of this reason, it is identified that social media can be used as a tool to analyze customer behavior. If relevant data can be gathered from the customers' social media feeds and if these data are analyzed properly, a clear idea to the companies what customers really think about their brand can be provided

Predicting annual stem diameter increment of selected tree species in Sinharaja rain forest by considering tree and stand level effects

Information on the diameter increment of tree species is important for developing a sustainable forest harvesting plan and for reforestation. Fitting a forest growth model for diameter increment can be utilized to get the information. The objective of this study was to develop a predictive model for the annual diameter increment of a multispecies stand in the Sinharaja Rain Forest in Sri Lanka. To fulfill this objective, four linear mixedeffect models were fitted to predict the annual diameter at breast height (dbh) increment of trees by using dbh, the natural logarithm of dbh, and species as a random effect. The model that contained random coefficients for the intercept term, dbh and log (dbh) were selected as the best-fitted model based on the Akaike Information Criterion (AIC) value and the likelihood ratio test. Then, the bestfitted model was expanded by adding other subsequent variables that describe the effects of competition from surrounding trees, and a size structure component, which is the maximum dbh. The final model comprised of this information dbh, log(dbh), stocking density, maximum dbh, and competition from trees smaller than the subject tree. Using the best-fitted final model, the annual dbh increment of the 10 selected abundant species was calculated. It was noted that all the selected species have growth rates that increase rapidly at the initial stage, and then reach its unique maximum growth rate. These increment patterns reflected that different species followed different annual dbh increment patterns. Therefore, this final model can be consolidated into an effective empirical model to project the future growth of a tropical rainforest

A preliminary study on occurrence and characterization of extended spectrum beta lactamase producing extra intestinal pathogenic <em>Escherichia coli</em> isolated from dogs

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Contribution of dissolved sulfates and sulfites in hydrogen sulfide emission from stagnant water bodies in Sri Lanka

Abstract Accumulation of sulfur-containing compounds and their bacterial mediated reductions have led to the emission of pungent odors from stagnant water bodies. This study is focused on the contribution of inorganic sulfur compounds in the emission of hydrogen sulfide. The measured dissolved oxygen levels have demonstrated good negative correlations with the dissolved sulfide levels implying the oxygen deficiency is the key for the reduction of sulfate ion and sulfite ion to sulfide ion. Particularly, the dissolved molar fractions of sulfide from the total dissolved sulfur compounds (sulfates, sulfites and sulfides) have a very good correlation with the dissolved oxygen for the stagnant water bodies except the artificially aerated prawn farms. For the stagnant water bodies with significant correlations, linear regressions are reported for them to be utilized in estimating one component of the regression from the measurement of the other. The measured data were further utilized to estimate the levels of hydrogen sulfide gas. The pH of the water bodies has confined much of the dissolved sulfides in the form of bisulfide ion and they can be easily escaped to the atmosphere upon acidification due to industrial discharges and/or acidic precipitations. The estimated levels of hydrogen sulfide just above the water surface were plotted for the most polluted stagnant water body in Sri Lanka for the pH range of 5-10 and temperature range of 25-35°C

Impact of Compliance with Principles on Board of Directors and Corporate Performance: Empirical Evidence from Sri Lankan Listed Companies

Board of directors in corporate governance is conceptualized as the perceived ability of a firm to constrain and direct corporate power so that it efficiently creates economic value and equitably distributes economic wealth. Accordingly, this study examines the relationship between the level of compliance with the principles on corporate governance related to the board of directors and corporate performance of listed firms in Sri Lanka using secondary data related to 133 listed companies from 2009 to 2016. This study constructed Board Index related to dimensions (principles): Chairmanship, Nomination Committee, Audit Committee, Remuneration Committee, and Re-election of directors, Company Secretary, Role of the Board, Board Meetings and Board Independence. This study employs panel regression model to examine the relationship between the Board Index (BI) and their relationship with corporate performance and performed with Hausman test for random and fixed effects. The findings indicated that the compliance with these principles are positively related to the financial performance and negatively related with market performance. Thus, this study provides empirical support for the agency perspective in the context of compliance requirements of board of directors leading to higher corporate performance. Insights of this research are offered to listed firms by the compliance of corporate governance principles have the potential to improve company performance. KEYWORDS: Agency Perspective, Audit Committee, Corporate Governance, Nomination committee, Remuneration Committee