Targhi M.Z.,100 Institute Road |
Van Dessel S.,100 Institute Road
Procedia Engineering | Year: 2015
Urban development projects have an immense impact on local microclimates which in turn affect the thermal comfort and space quality within a city. Thermally comfort outdoor spaces will encourage walkability in cities and improve public health and air quality. To design better urban environments it is necessary to measure and analyze outdoor thermal comfort in various climatic conditions, not only in warm but also in temperate and cold climates. Quantitative information helps us to adopt effective urban design solutions for existing and future urban environments. The overall objective of this research is to explore the variation of outdoor thermal comfort conditions affected by urban features. Therefore, the main aim of this paper is to discuss and assess the impact of urban geometry and form on microclimates of open spaces. Urban geometry and form will be investigated using field measurements and simulations in a developing urban environment. The measurements and simulations of climatic conditions will be executed in summer during the months of June and July, representing the hottest time of the year in downtown area of Worcester, Massachusetts, USA (humid continental, Dfb in Köppen climate classification). © 2015 The Authors. Published by Elsevier Ltd.
Monfaredzadeh T.,100 Institute Road |
Krueger R.,100 Institute Road
Procedia Engineering | Year: 2015
Sustainability is an established goal of future urban developments. More recently, the smart city concept has been employed to address issues associated with negative environmental externalities. Topics associated to people and communities, in the content of smart cities, have been neglected on the expense of a deeper understanding of the technological aspect of smart. This paper focuses on filling this gap by exploring its significance of sustainability and describing the interactions of these two concepts. This paper thus provides a particular conceptual focus on the potential of smart city strategies for improving the social sustainability of cities. © 2015 The Authors. Published by Elsevier Ltd.
Humi M.,Worcester Polytechnic Institute |
Humi M.,100 Institute Road
Journal of Guidance, Control, and Dynamics | Year: 2010
This paper studies low-eccentricity elliptic orbits of satellites in the gravitational field of a spherical body or in the equatorial plane of an oblate body subject to the influence of quadratic drag. Approximate analytic expressions for these orbits are presented for different models of the atmospheric density. The orbits computed from these analytic expressions are compared with those obtained from the numerical integration of the exact equations of motion with the same atmospheric model. For low-eccentricity orbits the deviation between the analytic and numerical orbits after ten revolutions is less than 5 m. These results generalize similar analytical expressions that were derived recently for nearly-circular orbits. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
McCurdy A.K.,100 Institute Road
Proceedings of the 30th International Thermal Conductivity Conference and the 18th International Thermal Expansion Symposium, Thermal Conductivity 30/Thermal Expansion 18 | Year: 2010
The thermal conductivity of anisotropic dielectric hexagonal crystals has been derived in the boundary-scattering regime where a fraction of the phonons are reflected from the sample boundaries. Results have been derived both for very long and finite length samples of square cross section in which the heat-flow axis is parallel to the hexagonal C axis. The reflection process has been analyzed using Snell's Law and the condition that there be zero stress normal to the reflecting surface. Reflection producing phonons of other polarizations has been considered using an expanded cross-section representation of the multiple reflection process.
Lui R.,100 Institute Road |
Wang Z.A.,University of Minnesota
Journal of Mathematical Biology | Year: 2010
In this paper, we study the existence and nonexistence of traveling wave solutions for the one-dimensional microscopic and macroscopic chemotaxis models. The microscopic model is based on the velocity jump process of Othmer et al. (SIAM J Appl Math 57:1044-1081, 1997). The macroscopic model, which can be shown to be the parabolic limit of the microscopic model, is the classical Keller-Segel model, (Keller and Segel in J Theor Biol 30:225-234; 377-380, 1971). In both models, the chemosensitivity function is given by the derivative of a potential function, Φ(v), which must be unbounded below at some point for the existence of traveling wave solutions. Thus, we consider two examples: Φ(v) = In v and Φ(v) = In[v/(1-v)]. The mathematical problem reduces to proving the existence or nonexistence of solutions to a nonlinear boundary value problem with variable coefficient on ℝ. The main purpose of this paper is to identify the relationships between the two models through their traveling waves, from which we can observe how information are lost, retained, or created during the transition from the microscopic model to the macroscopic model. Moreover, the underlying biological implications of our results are discussed. © 2009 Springer-Verlag.
Bhowmick S.,University of Massachusetts Dartmouth |
Medas M.,University of Massachusetts Dartmouth |
Mallick R.B.,100 Institute Road
International Journal of Sustainable Engineering | Year: 2012
Rutting is a common type of shear failure-related deformation in asphalt (hot mix asphalt, HMA) pavements. It occurs over time as a result of slow, repeated heavy loads from vehicles moving along the wheel path. This problem is most noticeable when the pavement is at a high temperature and its stiffness is the lowest. Previous investigations have concluded that flowing water in pipes embedded in the pavement leads to a reduction in surface temperature, and consequently rutting. However, the thermophysical properties of HMA limit the cooling effect to a small region immediately around the pipe. It is proposed that the area of cooling be enhanced by adding a highly conductive spreader layer below the pavement in conjunction with the pipe. A theoretical design optimisation has been carried out by exploring different aspects of the spreader layer-pipe spacing (W), depth of the pipe-spreader (D), spreader thickness (ts), thermal conductivity (ks) and variation in the boundary conditions. Finite element modelling predicts that a properly designed, highly conductive spreader layer will lead to a significant reduction in surface temperature with a minimal piping network leading to an extended functional life of the HMA pavement. © 2012 Copyright Taylor and Francis Group, LLC.
Su H.,Worcester Polytechnic Institute |
Zervas M.,100 Institute Road |
Cole G.A.,Worcester Polytechnic Institute |
Furlong C.,100 Institute Road |
Fischer G.S.,Worcester Polytechnic Institute
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2011
This paper presents the first prototype of a magnetic resonance imaging (MRI) compatible piezoelectric actuated robot integrated with a high-resolution fiber optic sensor for prostate brachytherapy with real-time in situ needle steering capability in 3T MRI. The 6-degrees-of-freedom (DOF) robot consists of a modular 3-DOF needle driver with fiducial tracking frame and a 3-DOF actuated Cartesian stage. The needle driver provides needle cannula rotation and translation (2-DOF) and stylet translation (1-DOF). The driver mimics the manual physician gesture by two point grasping. To render proprioception associated with prostate interventions, a Fabry-Perot interferometer based fiber optic strain sensor is designed to provide high-resolution axial needle insertion force measurement and is robust to large range of temperature variation. The paper explains the robot mechanism, controller design, optical modeling and opto-mechanical design of the force sensor. MRI compatibility of the robot is evaluated under 3T MRI using standard prostate imaging sequences and average signal noise ratio (SNR) loss is limited to 2% during actuator motion. A dynamic needle insertion is performed and bevel tip needle steering capability is demonstrated under continuous real-time MRI guidance, both with no visually identifiable interference during robot motion. Fiber optic sensor calibration validates the theoretical modeling with satisfactory sensing range and resolution for prostate intervention. © 2011 IEEE.
Wang J.,Worcester Polytechnic Institute |
Wang J.,100 Institute Road |
Lindeman R.W.,Worcester Polytechnic Institute
IEEE Symposium on 3D User Interfaces 2012, 3DUI 2012 - Proceedings | Year: 2012
Inspired by the Silver Surfer comics we developed a leaning-based surfboard interface which allows the user to fly in 3D virtual environments by shifting his/her center of mass on the board. The interface works in either an elastic tilt mode or an isometric balance mode offering different equilibrioceptive feedback to the user. Interested in how different levels of equilibrioceptive feedback influence the usability of this interface, a formal user study was conducted comparing the two modes in both separated and combined pitch and yaw travel tasks. Six of 30 subjects dropped out of the experiment because of cyber-sickness and were interviewed by the experimenter. Statistical analysis of data from the remaining subjects showed that although objectively there was no significant difference between the two modes regarding training effects and task performance, subjectively most subjects preferred the elastic tilt mode because of its intuitiveness, realism, fun, and sense of presence despite the greater fatigue and after effects (e.g., loss of balance) of using it. Based on the results we suggest a general preference of elastic devices and several design guidelines to future 3D VE travel interface designers. © 2012 IEEE.
Hu Y.,100 Institute Road |
Sunar B.,100 Institute Road
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010
In this paper, we proposed an improved memory integrity protection scheme to provide real-time protection service. In addition, we for the first time propose a provably secure scheme that takes advantage of the "error inheritance" property, which can minimize the costly check process that is normally required before every access. The security of the proposed scheme is rigorously analyzed and the performance is measured. The peak performance of the new scheme can be improved by up to a factor of 5 over a previously proposed scheme based on Merkle Trees. © 2010 Springer-Verlag.
Marceau G.,100 Institute Road |
Fisler K.,100 Institute Road |
Krishnamurthi S.,Brown University
SIGCSE'11 - Proceedings of the 42nd ACM Technical Symposium on Computer Science Education | Year: 2011
Good error messages are critical for novice programmers. Recognizing this, the DrRacket programming environment provides a series of pedagogically-inspired language subsets with error messages customized to each subset. We apply human-factors research methods to explore the effectiveness of these messages. Unlike existing work in this area, we study messages at a finegrained level by analyzing the edits students make in response to various classes of errors. We present a rubric (which is not language specific) to evaluate student responses, apply it to a course-worth of student lab work, and describe what we have learned about using the rubric effectively. We also discuss some concrete observations on the effectiveness of these messages.