Concrete is a staple material in the construction of buildings, pavements, bridges, and other structures. It is valued for its high compressive strength, although it is weak in tension and flexure. ...The experiment performed herein partially replaces the coarse aggregates found in concrete mixture with waste steel slag aggregate collected from the steelmaking process, in an effort to investigate possible beneficial changes to the concrete strength. By replacing 50% of the volume of coarse aggregate with steel slag aggregate, the final compressive strength was increased by roughly 30% (from approximately 1900 to 2500 psi). However, the unit weight of concrete increased from 145 pcf to 155 pcf. The tensile strength increased substantially, but should not be considered conclusive (and is elaborated within this dissertation). The modulus of elasticity also improved from 2.5 x 106 psi to 3.2 x 106 psi. The use of steel slag aggregate appears to be a viable partial substitute for coarse aggregate in situations where an increase in structural strength is preferred and the self-weight of the concrete itself is not an issue. In addition, its abundance and inexpensiveness provides a competitive, value-added bonus to its already-feasible status.
Structural grade lightweight aggregates have been successfully utilized in the construction of a wide range of superstructures as a component of structural lightweight concrete. More recently, ...structural grade lightweight aggregates have been employed in a wide variety of geotechnical applications including backfill behind retaining walls, load compensation conditions and slope stability situations. The following research investigates the viability of pumice aggregate as a viable structural grade lightweight aggregate for geotechnical fills. A series of tests including minimum and maximum dry unit weight tests, Standard Proctor Compaction tests, grain size analyses and direct shear tests were performed on varying samples of lightweight pumice aggregate. The results indicate that pumice aggregate has an average minimum and maximum dry unit weight of 30.73pcf and 38.44pcf, respectively; both lower than the specification for lightweight aggregates commonly used in geotechnical applications. The stability of lightweight pumice aggregate is relatively high with internal angle of friction values ranging from 34.5° to 44° corresponding to varying gradations and relative densities. The abrasions resistance of lightweight pumice aggregate was not directly tested during this research; however, the vertical displacement results obtained from the direct shear tests indicate that pumice aggregate may experience breakdown at stresses greater than 2tsf depending on grading and relative density. Although continued research is required, pumice aggregate is suitable as a structural grade lightweight aggregate under the correct conditions and geotechnical applications.
Experimental and control interception setups were designed, assembled and tested under a sweet gum tree anticipated for installation at Greenstreets in Queens, New York. The two setups were ...positioned adjacent to each other, without contact, on the roof of Drexel University's Main Building, Curtis Hall. The experiment measured catchment interception with and without the sweet gum tree from November 15th to November 17 th (2010) to calculate canopy interception from the sweet gum tree. No rainfall events occurred on November 15th. The experimental setup included a stemflow-measuring setup, attached to the trunk beneath the canopy and connected to a rain gauge, and a catchment: a concave hexagonal platform (ranging from 6' to 6.93' in length) underneath the canopy, which drains rainwater to collection buckets through 3/8"-diameter pipes. The control setup included the same platform, which drained rainwater to collection buckets through a funnel. Water level sensors were used to measure volume in the buckets for both setups. Total rainfall was measured using a rain gauge. Temperature, humidity and wind speed data were obtained from the National Weather Service Climate Report. Canopy architecture characteristics and branch dimensions were not measured. The total quantity of canopy interception (including interception loss, and temporarily-intercepted stemflow and throughfall), leaks under the setup, and rainwater adherences to the platform surface were measured at approximately 20% of rainfall. Based on literature (Viessman and Lewis, 2002 and Xiao et al., 2000), interception loss can be approximated at 15% of total rainfall. Subtracting interception loss from the measured 20% of rainfall, the remaining 5% of rainfall can be attributed to leaks, platform adherences, and temporarily-intercepted stemflow and throughfall. No direct measurements of interception loss, leaks, and platform adherences were made. Canopy interception area was calculated to be 8 ft², covering 25.5% of the concave hexagonal platform.
A system to extract quantitative measurements of the axial forces and resulting in-plane displacements of Mylar and latex drumheads undergoing a tuning procedure was developed and implemented as a ...step towards understanding the effect of detailed drumhead tension on drum acoustics. This system encompasses a combination of specialized hardware, software, experimental methods, and post-processing techniques. A customized test apparatus was implemented to quantify axial forces while simultaneously performing Digital Image Correlation studies on a drumhead to quantify the in-plane drumhead displacement. Axial forces in the ranges of 5–100 lbf and 5–35 lbf were developed in the tensioning members of said apparatus, in various radial configurations, such to produce in-plane radial displacement distributions with maximum values of 0.01 inches and 0.60 inches during the tensioning of Mylar and latex drumheads, respectively. The viability of the Digital Image Correlation method for this application was assessed extensively, and has proven to be a valid method for quantifying the displacement of latex drumheads. This system was less effective in quantifying the displacements of Mylar drumheads; it is believed that certain optical parameters require further optimization in order to improve the validity of the displacement data that can be extracted from these drumheads.
Voice over IP (VoIP) is a popular communication technology that is on its way to replacing the Public Switched Telephone Network (PSTN). The ubiquitous Internet along with the rise of camera-equipped ...smartphones and mobile computing devices has allowed VoIP to thrive. The Session Initiation Protocol (SIP) is one of the signaling protocols that makes VoIP possible, allowing it to be more flexible and even cheaper than other means of communication. Unfortunately, as with all IP-based technologies, VoIP systems are threatened by Denial of Service (DoS) attacks. A variety of solutions exist that attempt to safeguard SIP-based VoIP from DoS attacks, but they are either too simple to be reliable or are too sophisticated to be practical as a first line of defense. This paper presents the design and implementation of DoS Defender, a novel intrusion detection system (IDS) that is fast yet effective at detecting the onset of a DoS attack. DoS Defender employs a neural network for traffic pattern recognition and can be used as part of an automated system for the activation of countermeasures. The system has been evaluated in a simulated environment, where it achieves near perfect precision and recall for detecting DoS attacks.
Because of the growing need to reduce pollution and save money on fuel, electric and hybrid electric vehicle development is a clear and proven trend for the world's future vehicles. To further ...stimulate hybrid vehicle growth, intercollegiate competitions, like the Formula Hybrid Competition, challenge engineering students around the country to design and implement a goal-oriented vehicle. This work provides a preliminary body of research on various drivetrain types and components such as electric motors, motor controllers, batteries, generators, and gasoline engines. Using this knowledge, a design methodology is executed to provide the sizing, selection, and implementation of an electric powertrain in a controlled laboratory test stand. Along the way, drivetrain components are sized and chosen using a combination of hand calculations and computer simulations. Once a drivetrain design was fully identified and sourced, the drive system was built on a test stand. Preliminary testing and shakedown were performed to verify the compatibility of the system and to prepare it for future studies. Various computer programs, electronic hardware, and mechanical systems including an eddy current dynamometer were used to help the test stand perform its functions. The powertrain test stand must control and measure the motor performance variables necessary for complete motor characterization such as speed, torque, voltage, and current. The test stand will serve future vehicle design efforts and student educational functions in the engine testing lab at The Cooper Union. The main objective of this project was to provide a safe, flexible, and instructional test stand to serve the anticipated needs of future vehicle design efforts at Cooper Union.
Objectives. To measure the impact of an educational intervention directed at both patients and their primary care physicians about prostate-related conditions.
Methods. We used a randomized, control ...design for 50 physicians in 33 rural primary care practices from New England and Arkansas and a probability sample of 2402 of their male patients. For the physicians, we mailed two newsletters, conducted two face-to-face research staff visits, and provided printed educational manuals about the management of prostate conditions. For the patients, mailed educational pamphlets were targeted to the baseline symptom levels. After 18 months, 87% of patients and 92% of physicians completed a final survey. The patient survey measured health status, urinary symptoms and bother, treatments received, and prostate-related knowledge. The final physician survey asked them about their management of common prostate conditions.
Results. Before randomization, most men (59%) said they knew little or nothing about prostate problems that affect urination, and 63% also reported “little” or “no” knowledge about prostate-specific antigen testing. Eighteen months later, we observed no differences between the intervention and control patients in the measures of health status, urinary symptoms and bother, treatments received, and prostate-related knowledge. The intervention, physicians’ knowledge, and self-reported practices for managing common prostate conditions were no better than the control physicians’.
Conclusions. This commonly used education strategy had no measurable impact on prostate-related care.
The hypothesis that women are more discriminating in naming colors than men is tested by asking 18 M & 18 F adults to write the names of the colors of sweaters modeled alternately by a M & a F. The ...free-response color descriptions were then analyzed to see if Ms & Fs named the colors in significantly different ways. Results indicate that: Fs describe most colors more specifically than Ms; Fs generally use specific color terms in naming, while Ms use combinations of basic color terms & saturation adjs; & Fs seem to acquire more specific terms for colors (eg, pink, dark red, yellow, & medium blue), while Ms exhibit equal or greater specificity than Fs for some colors -- grey, brown, & green. It is suggested that the different upbringing of Ms & Fs is responsible for this difference in specificity, ie, the colors Fs describe specifically predominate in cosmetics, clothing, & decorations, & the colors that Ms describe specifically predominate in men's clothing & outdoor activities. 3 Tables. I. Mielonen
PDF
