Compressed Sensing-Based Range-Doppler Processing Method for Passive Radar

Passive radar (PR) systems use the existing transmitters of opportunity in the environment to perform tasks such as detection, tracking, and imaging. The classical cross-correlation based methods to obtain the range-Doppler map have the problems of high sidelobe and limited resolution due to the influence of signal bandwidth. In this paper, we propose a novel range-Doppler processing method based on compressed sensing (CS), which performs sparse reconstruction in range and Doppler dimensions to achieve high resolution and reduces sidelobe without excessive computational burden. Results from numerical simulations and experimental measurements recorded with the Chinese standard digital television terrestrial broadcasting (DTTB) based PR show that the proposed method successfully handles the range-Doppler map formatting problem for PR and outperforms the existing CS-based PR processing methods.

Beyond the façade of generosity—Regional stereotypes within the same national culture influence prosocial behaviors

We analyzed prosocial behaviors in a field experiment (N = 307) conducted in an urban context (Timisoara, Banat region, Romania), starting from a classical Cross-Cultural Psychology research organized in UK and Iran by Collet & O’Shea in 1976. If the evoked study is focused on comparing prosocial behaviors in two very different national cultures (UK vs. Iran), we compared helping strangers strategies within the same national culture in relation to the regional identities of the help-seeking subjects. A behavioral scenario was created by asking naïve participants to offer support and give directions to a place even if they did not know its whereabouts. Drawing on social identity theory, it was tested whether regional belonging of the help-seeker (in-group vs. out-group) predicts the availability of help-givers for offering help, their availability for giving wrong directions, as well as their emotional expressiveness. Results are interpreted within the perspective of social distance between groups and show that the more distant regional identities are perceived to be, the less generous help-givers are, both in terms of their decision to help and to give wrong directions, as well as in their expressed emotions.

Der wechselseitige Einfluss von Selbstkonzept und Leistung bei Grundschulkindern im Lichte verschiedener längsschnittlicher Analysemethoden

The association between academic self-concept and achievement is assumed to be reciprocal. Although a large amount of research has been interpreted as demonstrating a bidirectional association, these results are typically based on variants of the classical cross-lagged panel model and often include only one achievement indicator in the models. Results with more recently developed methodological approaches, for example, the random-intercept cross-lagged panel model, are hardly found so far. The present study aimed to test the association between math self-concept and math achievement with different models to evaluate whether positive cross effects can be demonstrated with the alternatives models. Drawing on a sample of 1952 elementary students from Grade 1 to Grade 3, results of structural equation modeling yielded noticeable differences. While effects of achievement on self-concept can been demonstrated in all models, the evidence for the reverse effects is rather weak. The results are discussed with regard to the theoretical assumptions and appropriate methodological approaches.

Celts, Romans, Britons

This interdisciplinary volume of essays examines the real and imagined role of Classical and Celtic influence in the history of British identity formation, from late antiquity to the present day. In so doing, it makes the case for increased collaboration between the fields of Classical reception and Celtic studies, and opens up new avenues of investigation into the categories “Celtic” and “Classical”, which are presented as fundamentally interlinked and frequently interdependent. In a series of chronologically arranged chapters, beginning with the post-Roman Britons and ending with the 2016 Brexit referendum, it draws attention to the constructed and historically contingent nature of the Classical and the Celtic, and explores how notions related to both categories have been continuously combined and contrasted with one another in relation to British identities. Britishness is revealed as a site of significant Celtic-Classical cross-pollination, and a context in which received ideas about Celts, Romans, and Britons can be fruitfully reconsidered, subverted, and reformulated. Responding to important scholarly questions that are best addressed by this interdisciplinary approach, and extending the existing literature on Classical reception and national identity by treating the Celtic as an equally relevant tradition, the volume creates a new and exciting dialogue between subjects that all too often are treated in isolation, and sets the foundations for future cross-disciplinary conversations.

V-belts and Their Performance Resulting Fromtheir Inner Hybrid Structure

Paper provides a study and comparison ofnarrow and classical cross-sections of five V-belts withdifferent inner structure, material composition and shape.The performance is evaluated by non-contact monitoringof transversal vibration velocity together with belttemperature caused by friction and vibrations at variousoperational states when changing the loading, revolutionsof driver pulley and tensioning force. Moreover, thevibration regimes are observed. The study presentswhether concave sides, adhesion layer, higher compressioncore, transverse reinforcing fibers, notches, wrap ofprofile, naked belt sides cause the different performance.

An Improved Method for the Position Detection of a Quadrant Detector for Free Space Optical Communication

In free space optical communication, a beacon light loses too much energy after a long-distance transmission and faces strong interference from background light. The beacon light illuminated on a quadrant detector (QD) is so weak that the output signal-to-noise ratio (SNR) of a QD is very low, which leads to a significant decrease in the accuracy of the direct position detection method. To solve this problem, an improved light spot position detecting method is proposed. Since the background light and the dark current noise are white noise, we could consider concentrating the energy of QD output signal at a certain frequency point to enhance the output SNR. Therefore, a cosine signal is used to modulate the intensity of a beacon light at the transmitting end. Then the QD output photocurrents are also cosine signals with the same frequency as the modulating signal. Putting the photocurrent signals into a cross-correlation operation with a reference signal, which is the same as the modulating signal, can enhance the QD output SNR at a certain frequency point. Unfortunately, the result of the classical cross-correlation is attenuated with increasing delay. It is hard to detect the amplitude of the classical cross-correlation result. So, we used cyclic cross-correlation to obtain a stable correlation result to detect its amplitude accurately. The experiment results show that even when the QD output SNR is less than −17 dB, the detection root-mean-square error of the proposed method is 0.0092 mm, which is a quarter of the direct position detection method. Moreover, this method only needs a small amount of data to accomplish the calculation and is especially suitable for real-time spot position detection.