Stevens Institute of Technology

About: Stevens Institute of Technology is a education organization based out in Hoboken, New Jersey, United States. It is known for research contribution in the topics: Computer science & Cognitive radio. The organization has 5440 authors who have published 12684 publications receiving 296875 citations. The organization is also known as: Stevens & Stevens Tech.

Moving Target Detection Using Distributed MIMO Radar in Clutter With Nonhomogeneous Power

Abstract: In this paper, we consider moving target detection using a distributed multiple-input multiple-output (MIMO) radar on stationary platforms in nonhomogeneous clutter environments. Our study is motivated by the fact that the multistatic transmit-receive configuration in a distributed MIMO radar causes nonstationary clutter. Specifically, the clutter power for the same test cell may vary significantly from one transmit-receive pair to another, due to azimuth-selective backscattering of the clutter. To account for these issues, a new nonhomogeneous clutter model, where the clutter resides in a low-rank subspace with different subspace coefficients (and hence different clutter power) for different transmit-receive pair, is introduced and the relation to a general clutter model is discussed. Following the proposed clutter model, we develop a generalized-likelihood ratio test (GLRT) for moving target detection in distributed MIMO radar. The GLRT is shown to be a constant false alarm rate (CFAR) detector, and the test statistic is a central and noncentral Beta variable under the null and alternative hypotheses, respectively. Simulations are provided to demonstrate the performance of the proposed GLRT in comparison with several existing techniques.

Energetics and Stability of Translating Media with an Arbitrarily Varying Length

Abstract: The linear dynamics of a class of translating media with an arbitrarily varying length is investigated. The tension in the media arising from their longitudinal accelerations is incorporated. The dynamic stability of the continuous media relative to the inertial and moving coordinate systems is studied from the energy standpoint. The exact expressions for the rates of change of energies of media are derived and interpreted from both control volume and system viewpoints. The stability analyses relative to the inertial and moving coordinate systems result in the same predictions. Examples including a robotic arm through a prismatic joint and an elevator cable in a high-rise building illustrate the analysis. In particular, the results explain an inherent unstable shortening cable behavior encountered in elevator industry.

The effects of oxygen and humidity on friction and wear of diamond-like carbon films

Abstract: Diamond-like carbon (DLC) films were prepared on Si(100) wafers by plasma-assisted chemical vapor deposition at a pressure of 900 mTorr. Their wear rates and friction coefficients against a silicon nitride ball were measured in a pin-on-disk tribometer in argon and air with varying relative humidities. In 50% relative humidity, the measured wear rates of the ball and DLC were of the order of 10−8 mm3 N−1 m−1 and 10−7 mm3 N−1 m−1 respectively. In dry argon, dry air and 100% humid air, the wear rates of DLC were 10−9, 10−9 and 10−8 mm3 N−1 m−1, but that of the ball was below the detection limit. The measured friction coefficients were 0.06 in dry argon, 0.08 in 50% humid air and 0.09 in 100% humid argon, and around 0.2 in 50% humid argon, dry and 100% in humid air. In dry argon, the contact area of the ball was covered with material transferred from the DLC film during sliding; the low friction coefficient and wear rate measured in dry argon are attributed to this material. In dry and humid air, surface layers of DLC were oxidized by a tribochemical reaction forming a CO bond. They covered the contact area of both the DLC film and the ball. This film increased friction coefficients, but it acted as a protective coating when its thickness was sufficient to prevent direct contact of the DLC film against the ball in 100% humid air.

Remote versus hands-on labs: a comparative study

Abstract: Advocates of hands-on laboratories and advocates of simulation have debated for years. Proponents of hands-on laboratories argue that student engineers need to be exposed to the physical experiences-and the uncertainties-of real environments. Advocates of simulation argue that physical labs are wasteful-they tie up badly needed space, and consume student's time in menial set-up and tear-down procedures. Now remote laboratories have appeared as a third option. These laboratories are similar to simulation techniques in that they require minimal space and time, because the experiments can be rapidly configured and run over the Internet. But unlike simulations, they provide real data. It is unknown what the relative effectiveness of hands-on, simulated, and remote laboratories is. This paper presents a model for testing this relative effectiveness, and discusses the results of a preliminary assessment study comparing versions of remote labs versus hands-on labs in a junior-level mechanical engineering course on machine dynamics and mechanisms.

Detection and Localization of Multiple Spoofing Attackers in Wireless Networks

Abstract: Wireless spoofing attacks are easy to launch and can significantly impact the performance of networks. Although the identity of a node can be verified through cryptographic authentication, conventional security approaches are not always desirable because of their overhead requirements. In this paper, we propose to use spatial information, a physical property associated with each node, hard to falsify, and not reliant on cryptography, as the basis for 1) detecting spoofing attacks; 2) determining the number of attackers when multiple adversaries masquerading as the same node identity; and 3) localizing multiple adversaries. We propose to use the spatial correlation of received signal strength (RSS) inherited from wireless nodes to detect the spoofing attacks. We then formulate the problem of determining the number of attackers as a multiclass detection problem. Cluster-based mechanisms are developed to determine the number of attackers. When the training data are available, we explore using the Support Vector Machines (SVM) method to further improve the accuracy of determining the number of attackers. In addition, we developed an integrated detection and localization system that can localize the positions of multiple attackers. We evaluated our techniques through two testbeds using both an 802.11 (WiFi) network and an 802.15.4 (ZigBee) network in two real office buildings. Our experimental results show that our proposed methods can achieve over 90 percent Hit Rate and Precision when determining the number of attackers. Our localization results using a representative set of algorithms provide strong evidence of high accuracy of localizing multiple adversaries.