Research in Nonlinearity of Surface Acoustic Wave Devices

Surface acoustic wave (SAW) devices are one of the indispensable components in the radio frequency (RF) front-end of mobile phones. With the development of mobile communication technology, the requirements for linear specification of devices are more and more strict. Nonlinear distortions of SAW devices have a serious influence on the application of mobile RF modules. To satisfy the strict requirement of linearity of communication system, it is necessary to understand the generation mechanism of nonlinearity and study the accurate modeling, appropriate measurement methods, and nonlinear response elimination technology. In this paper, we summarize the research progress on the nonlinearity of SAW devices in recent years from four aspects: the generation mechanism, simulation methods, measurement system, and suppression technology. The nonlinear harmonics with the nonlinear Mason equivalent circuit model are simulated. Furthermore, harmonics and intermodulation signals of SAW filters are tested by the authors. Thanks to these research studies, it is of great significance to the development of future RF front-end modules with high linear SAW devices.

Strategy use moderates the relation between working memory capacity and fluid intelligence: A combined approach

This study investigated whether the strength of the link between working memory capacity (WMC) and fluid intelligence (Gf) differs as people use different strategies to solve Gf problems. A sample of 214 university students completed three complex span tasks and Raven's Advanced Progressive Matrices (APM). Strategic behavior was measured by both a strategy questionnaire and eye tracking. Using latent profile analysis, three strategies described as constructive matching, response elimination, and isolate-and-eliminate were identified. Participants adopting constructive matching and response elimination exhibited substantial differences in the eye-movement measures across the APM items, confirming the validity of the strategy questionnaire in combination of latent profile analysis for determining strategy use. Furthermore, strategy use moderated the relationship between WMC and APM performance. The link between WMC and APM scores was significantly higher for participants who used isolate-and-eliminate (r = .54) and response elimination (r = .63) than that for participants who used constructive matching (r = .27). Our findings suggest that the simple dichotomy of strategy use in the APM is not tenable, and the extent to which WMC relates to performance on the APM varies as a function of strategy use.

Manipulate Me

The cube construction task represents a novel format in the assessment of spatial ability through mental cube rotation tasks. Instead of selecting the correct answer from several response options, respondents construct their own response in a computerized test environment, leading to a higher demand for spatial ability. In the present study with a sample of 146 German high-school students, we tested an approach to manipulate the item difficulties in order to create items with a greater difficulty range. Furthermore, we compared the cube task in a distractor-free and a distractor-based version while the item stems were held identical. The average item difficulty of the distractor-free format was significantly higher than in the distractor-based format ( M = 0.27 vs. M = 0.46) and the distractor-free format showed a broader range of item difficulties (.02 ≤ pi ≤ .95 vs. .37 ≤ pi ≤ .63). The analyses of the test results also showed that the distractor-free format had a significantly higher correlation with a broad intelligence test ( r = .57 vs. r = .17). Reasons for the higher convergent validity of the distractor-free format (prevention of response elimination strategies and the broader range of item difficulties) and further research possibilities are discussed.

Affine-Function Transformation-Based Object Matching for Vehicle Detection from Unmanned Aerial Vehicle Imagery

Vehicle detection from remote sensing images plays a significant role in transportation related applications. However, the scale variations, orientation variations, illumination variations, and partial occlusions of vehicles, as well as the image qualities, bring great challenges for accurate vehicle detection. In this paper, we present an affine-function transformation-based object matching framework for vehicle detection from unmanned aerial vehicle (UAV) images. First, meaningful and non-redundant patches are generated through a superpixel segmentation strategy. Then, the affine-function transformation-based object matching framework is applied to a vehicle template and each of the patches for vehicle existence estimation. Finally, vehicles are detected and located after matching cost thresholding, vehicle location estimation, and multiple response elimination. Quantitative evaluations on two UAV image datasets show that the proposed method achieves an average completeness, correctness, quality, and F1-measure of 0.909, 0.969, 0.883, and 0.938, respectively. Comparative studies also demonstrate that the proposed method achieves compatible performance with the Faster R-CNN and outperforms the other eight existing methods in accurately detecting vehicles of various conditions.

Desarrollo a orden estricto C-4 del Modelo Semirelativista LRESC para el cálculo de propiedades magnéticas moleculares

En el presente trabajo se abordó el estudio de una de las posibles limitaciones de un método propio que introduce correcciones de efectos relativistas en el cálculo y análisis de propiedades magnéticas. Se trata del modelo teórico expresado en 2-coinponentes, denominado <i>Linear response elimination of smallcornponents</i> (LRESC), que parte del formalismo perturbativo de RSPT en 4- componentes. Mediante transformaciones adecuadas se obtienen operadores de corrección relativista dentro de una serie de potencias en <i>c</i>^-1. Corno punto inicial del trabajo se retornó el desarrollo de este modelo (Melo et al., 2003). En el mismo, se calcularon los términos diamagnéticos con correcciones a orden <i>c</i>^-4 para el apantallamiento magnético nuclear; se consideró en dicho trabajo solo el primer término del desarrollo en serie de la inversa de la diferencia de energías. En este trabajo se incluyen todos los términos co1Tectivos de dicha inversa que contribuyen al desarrollo en serie al orden <i>c</i>^-4. Se demuestra aquí que, a orden <i>c</i>^-4, el primer término de dicha serie incluye todas las correcciones hasta este orden. Por otro lado se desarrolló un esquema de expansión de la serie que permite hallar los términos correctivos a todo orden en potencias de <i>c</i>^-1.