Interference management schemes for multi‐user cooperative wireless networks

Cooperative communication is a promising technique for future wireless networks. It can be used in improving communication reliability and enhancing spectrum efficiency by using the broadcast nature of radio communication and exploiting cooperative diversity. However, its performance gain degrades in the presence of co‐channel interference, which makes it essential to propose interference mitigation schemes. In this paper, we introduce three cooperative communication schemes with interference management for multi‐user cooperative wireless networks. The first scheme (best relay selection) is used as a performance benchmark because it completely avoids the interference problem by using the Frequency‐Division Multiple Access technique. The second scheme (best available relay selection) maximizes the received signal‐to‐noise ratio while keeping the interference levels below a certain threshold, and the third scheme (General Order Relay and User Selection) is based on iterative resource allocation algorithm. We derive exact closed‐form expressions of average bit error probability, outage probability, and average consumed power for the proposed schemes. Simulations are used to validate the analytical results. The results confirm the advantage of the proposed cooperation schemes in enhancing the system performance and improving the interference management. Copyright © 2015 John Wiley & Sons, Ltd.     

The affective component of the secure base schema: Affective priming with representations of attachment security.

Using an affective priming procedure (S. T. Murphy & R. B. Zajonc, 1993), 7 studies examined the effects of the contextual activation of representations of attachment security (secure base schema) on the evaluation of neutral stimuli under either neutral or stressful contexts. In all the studies, participants also reported on their attachment style. Results indicated that the subliminal priming of secure base representations led to more positive affective reactions to neutral stimuli than did the subliminal priming of neutral or no pictures under both neutral and stressful contexts. Although the subliminal priming of positively valued, attachment-unrelated representations heightened positive evaluations under neutral contexts, it failed to elicit positive affect under stressful contexts. The results also revealed interesting effects of attachment style. The discussion focuses on the affective component of the secure base schema. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

WIP Remodeling Actin behind the Scenes: How WIP Reshapes Immune and Other Functions

Actin polymerization is a fundamental cellular process regulating immune cell functions and the immune response. The Wiskott-Aldrich syndrome protein (WASp) is an actin nucleation promoting factor, which is exclusively expressed in hematopoietic cells, where it plays a key regulatory role in cytoskeletal dynamics. WASp interacting protein (WIP) was first discovered as the binding partner of WASp, through the use of the yeast two hybrid system. WIP was later identified as a chaperone of WASp, necessary for its stability. Mutations occurring at the WASp homology 1 domain (WH1), which serves as the WIP binding site, were found to cause the Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). WAS manifests as an immune deficiency characterized by eczema, thrombocytopenia, recurrent infections, and hematopoietic malignancies, demonstrating the importance of WIP for WASp complex formation and for a proper immune response. WIP deficiency was found to lead to different abnormalities in the activity of various lymphocytes, suggesting differential cell-dependent roles for WIP. Additionally, WIP deficiency causes cellular abnormalities not found in WASp-deficient cells, indicating that WIP fulfills roles beyond stabilizing WASp. Indeed, WIP was shown to interact with various binding partners, including the signaling proteins Nck, CrkL and cortactin. Recent studies have demonstrated that WIP also takes part in non immune cellular processes such as cancer invasion and metastasis, in addition to cell subversion by intracellular pathogens. Understanding of numerous functions of WIP can enhance our current understanding of activation and function of immune and other cell types.     

Attachment, Caregiving, and Altruism: Boosting Attachment Security Increases Compassion and Helping.

Recent studies based on J. Bowlby's (1969/1982) attachment theory reveal that both dispositional and experimentally enhanced attachment security facilitate cognitive openness and empathy, strengthen self-transcendent values, and foster tolerance of out-group members. Moreover, dispositional attachment security is associated with volunteering to help others in everyday life and to unselfish motives for volunteering. The present article reports 5 experiments, replicated in 2 countries (Israel and the United States), testing the hypothesis that increases in security (accomplished through both implicit and explicit priming techniques) foster compassion and altruistic behavior. The hypothesized effects were consistently obtained, and various alternative explanations were explored and ruled out. Dispositional attachment-related anxiety and avoidance adversely influenced compassion, personal distress, and altruistic behavior in theoretically predictable ways. As expected, attachment security provides a foundation for care-oriented feelings and caregiving behaviors, whereas various forms of insecurity suppress or interfere with compassionate caregiving. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analytic extraction of the elastic coupling mechanisms in composite blades

An aeroelastic model for a hingeless helicopter blade with a composite flex-beam is presented. The model employs structural analysis for laminated flex-beams of solid cross-sections with symmetric layup, and the study encompasses configurations with Beamwise Bending-Twist coupling and Chordwise Bending-Twist coupling. The structural dynamics of blades with coupled composite flex-beams is studied by a special purpose methodology that allows the creation of a refined uncoupled reference blade for each case. This procedure enables the determination of the net effects which are induced by the elastic couplings. By examining the stability characteristics of the blades in the frequency domain and their response in the time domain, the paper supplies additional information regarding the trade-off between stability and vibration characteristics in both the transient and the steady-state, forward-flight regimes. The analysis also examines the effect of different types of composite materials and quantitatively identifies the relation between elastic properties and their potential to improve blade stability margins.     

Multifunction wide-band array design

High-performance active arrays operating over C, X, and Ku-band have been demonstrated using newly developed designs of wide-band radiating elements and wide-band monolithic microwave integrated circuits (MMICs). The advanced shared aperture program (ASAP) explored the development of wide-band multifunction arrays capable of simultaneous and time interleaved radar, electronic warfare, and communications functions. Two iterations of radiating element and transmit/receive (T/R) module design were completed during this program. The radiating aperture design approach, overall array concepts, and current design technology and performance are summarized     

Parametric equations for T-butt weld toe stress intensity factors

This paper describes the generation of parametric equations for weld toe stress intensity factors. The methodology employed used a two-dimensional finite element analysis to evaluate the ‘crack opening’ stress distribution in the uncracked plane of T-butt geometries. This was then used as input into a dedicated weight function solution for the determination of stress intensity factors. The final parametric equations describe the stress intensity factor distributions for tension and bending as a function of plate thickness, weld attachment width, weld angle, weld root radius, crack length and crack shape. The equations are compared and validated against a wide spectrum of published values and appear by comparison accurate and wide ranging. The validation exercise uncovered situations where present design guidance is unconservative.     

CONTROL VOLUME FINITE ELEMENT NUMERICAL SIMULATION OF MIXED CONVECTION IN AN AIR-COOLED CAVITY

This paper presents a numerical study of transient mixed convection of laminar flows in an air-cooled cavity in which a fluid is injected at a temperature lower than the initial temperature of the cavity. A control volume finite element method (CVFEM) using triangular elements is employed to discretize the governing equations. The performance of the numerical algorithm is first tested. In order to investigate the quality of the ventilation and cooling, the dynamic and thermal fields are numerically determined for a large range of Reynolds and Richardson numbers and for different inlet-outlet locations. Cooling efficiency is examined at transient and at steady regimes.