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.

Team Stressors, Management Support, and Project and Process Outcomes in New Product Development Projects

Abstract: Stress is an important research area in the group and organizational behavior literature, yet it is underestimated in the new product development scholarship. In particular, the impact of team stressors on project and process outcomes was not empirically investigated in NPD project teams. In this study, we test the influence of team stressors, consisting of team crisis and anxiety, on the project/process outcomes, such as team learning, speed-to-market, new product success and proficiently executing the each stage of product development process, including the degree of management support during the project. By investigating 96 NPD projects, we found that when a high degree of management support is seen during the project, team crisis positively influences team learning, speed-to-market and new product success, and team anxiety positively impacts speed-to-market. Interestingly, when low management support was noted during the project, we were not able to find any statistical association between team crisis and anxiety, and project outcomes. Also, we found that when there was a high level of management support, team anxiety is positively related to the proficiency in executing the idea generation, market/technological assessment, product development, and product commercialization stages; and team crisis is positively related to the market/technological assessment, product development, product testing, and product commercialization stages. Further, we found that team anxiety influences the proficiency in the product development stage regardless of low or high level of management support. Next, managerial and theoretical implications were discussed.

Vibro-acoustic modulation nondestructive evaluation technique

Abstract: Nonlinear acoustic technique has been recently introduced as a new tool for nondestructive inspection and evaluation of fatigued, defective, and fractured materials. Various defects such as cracks, debonding, fatigue, etc. lead to anomalous high level of nonlinearity as compared with flawless structures. One of the acoustic manifestations of such nonlinearity is the modulation of ultrasound by low frequency vibration. Two methods employing the nonlinear interaction of ultrasound and vibration were developed, namely vibro-modulation (VM) and impact-modulation (IM) methods. VM method employs forced harmonic vibration of a structure tested, while IM method uses impact excitation of structure natural modes of vibration. The feasibility tests were carried out for different objects and demonstrated high sensitivity of the methods for detection of cracks in steel pipes and pins, bonding quality in titanium and thermoplastic plates used for airspace applications, cracks in combustion engine, adhesion flaws in bonded composite structures, and cracks and corrosion in reinforced concrete. The model of the crack allowing to describe the modulation of sound by vibration is discussed. The developed nonlinear technique demonstrated certain advantages as compared with the conventional linear acoustic technique, specifically discrimination capabilities, sensitivity, and applicability to highly inhomogeneous structures.

Channel Estimation for Millimeter-Wave Multiuser MIMO Systems via PARAFAC Decomposition

Abstract: We consider the problem of uplink channel estimation for millimeter wave (mmWave) systems, where the base station (BS) and mobile stations (MSs) are equipped with large antenna arrays to provide sufficient beamforming gain for outdoor wireless communications. Hybrid analog and digital beamforming structures are employed by both the BS and the MS due to hardware constraints. We propose a layered pilot transmission scheme and a CANDECOMP/PARAFAC (CP) decomposition-based method for joint estimation of the channels from multiple users (i.e., MSs) to the BS. The proposed method exploits the intrinsic low-rank structure of the multiway data collected from multiple modes, where the low-rank structure is a result of the sparse scattering nature of the mmWave channel. The uniqueness of the CP decomposition is studied, and the sufficient conditions for essential uniqueness are obtained. The conditions shed light on the design of the beamforming matrix, the combining matrix, and the pilot sequences, and meanwhile provide general guidelines for choosing system parameters. Our analysis reveals that our proposed method can achieve a substantial training overhead reduction by leveraging the low-rank structure of the received signal. Simulation results show that the proposed method presents a clear advantage over a compressed sensing-based method in terms of both estimation accuracy and computational complexity.

Snow grain size retrieved from near-infrared radiances at multiple wavelengths

Abstract: A comprehensive forward radiative transfer model is used to construct a snow grain size retrieval algorithm that relies on the use of NIR radiances. Data collected by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at the wavelengths 0.86, 1.05, 1.24 and 1.73 µm are used to retrieve snow grain size. Based on a single-layer (homogeneous) snow model, the retrieved snow grain size appears to depend on wavelength. The photon penetration depth defined as the e-folding flux attenuation depth has be computed for different snow grain sizes and different wavelengths. It reveals that this apparent wavelength dependence occurs because (i) the snow grain size generally increases with depth, and (ii) the photon penetration depth decreases with increasing wavelength. The results show that the wavelength dependence of the photon penetration depth can be used to retrieve the depth dependence of the snow grain size.

High-speed modulation and free-space optical audio/video transmission using quantum cascade lasers

Abstract: The high-speed direct modulation response of mid-infrared quantum cascade (QC) lasers is investigated up to a frequency of 2 GHz, showing high-frequency data transmission capabilities. The application of QC lasers to optical wireless communications is discussed and demonstrated in a free-space television link over a distance of 70 m.