A method for visualizing sound propagation in solids and liquids

A new method for visualizing sound propagation in solids and liquids is described in this paper. The method can show the sound propagation process dynamically in two dimensions. Compared with Schlieren method and dynamic photo-elastic method, this method cannot only show the sound field distribution in liquid and solid at different time moments, but also can be applied to non-transparent solid. In addition, it does not strictly require small residual stress of the sample. The sample can, therefore, be easily made. Because the acoustic field is obtained by indirect measurements, the recording can be affected by the after-shock of the receiving sensor and is prone to the influence of the direct wave of the liquid. Putting an aluminum plate into a liquid, we recorded the compression wave, shear wave and surface wave in the aluminum and, in the liquid we also recorded the direct wave and three head waves, which are directly coupled with the compression wave, shear wave and surface wave respectively. The recording clearly depicts the coupling relationship of the sound waves through the interface between the aluminum and the liquid. Putting a plexiglass into a liquid, we also recorded the sound waves in the plexiglass and the coupling relationship between the sound waves in the two mediums.

Visual Passive Ranging Method Based on Re-entrant Coaxial Optical Path and Experimental Verification

To overcome the shortcomings of the traditional passive ranging technology based on image, such as poor ranging accuracy, low reliability and complex system, a new visual passive ranging method based on re-entrant coaxial optical path is presented. The target image is obtained using double cameras with coaxial optical path. Since there is imaging optical path difference between the cameras, the images are different. In comparison of the image differences, the target range could be reversed. The principle of the ranging method and the ranging model are described. The relationship among parameters in the ranging process is analyzed quantitatively. Meanwhile,the system composition and technical realization scheme are also presented. Also, the principle of the method is verified by the equivalent experiment. The experimental results show that the design scheme is correct and feasible with good robustness. Generally, the ranging error is less than 10% with good convergence. The optical path is designed in a re-entrant mode to reduce the volume and weight of the system. Through the coaxial design,the visual passive range of the targets with any posture can be obtained in real time. The system can be widely used in electro-optical countermeasure and concealed photoelectric detection.

Seismic hazard analysis for central-western Argentina

In this study, we present a PSHA（Probabilistic Seismic Hazard Analysis） for the city of San Juan, which is located in the central-western region of Argentina（30°S-35.5°S; 66.5°W-71°W）. In addition to crustal earthquakes provided by catalogues, recent paleoseismological and neotectonic investigations have permitted to consider events which occurred during the last 400 years.Four seismogenic sources that could cause damages to the studied site corresponding to Precordillera,Western Sierras Pampeanas, Basement of the Cuyana Basin and Cordillera Principal were identified.Based on the evaluation of the contribution of these sources,maximum moment magnitudes above 7.5（Mw） are expected.High values of SA（spectral acceleration）（0.2 and 1 s periods） and PGA（peak ground acceleration） were found in the city of San Juan, which suggests that it is located in a zone of high seismic hazard.Finally, the obtained SA spectra were compared with the seismic-resistant construction standards of Argentina INPRES-CIRSOC 103 [1]. Results suggest that for the city of San Juan and for a return period of475 years, it covers the seismic requirements of the structures.

Element-Partition-Based Methods for Visualization of 3D Unstructured Grid Data

E lement- partition- based methods for visualization of 3D unstructured grid data are presented. First, partition schemes for common elements, including curvilinear tetrahedra, pentahedra, hexahedra, etc., are given, so that complex elements can be divided into several rectilinear tetrahedra, and the visualization processes can be simplified.Then, a slice method for cloud map and an iso-surface method based on the partition schemes are described.

Phase Diagram of the System KCl-CsBr-CaBr_2

A computer prediction for the regularities of formation of binary bromide system was made. The results indicate that CsBr-CaBf2 molten salt system is binary complex compound-forming system. The phase diagram of CSBr-CaBt2 system has been determined by visual polythermal method in order to prove the prediction. The phase diagrams of the quasibinary system KCl-CsBr, KCl-CaBr2 and the quasiternary system CsBr-CaBr2-KCl were determined by using visual polythermal method. The phase diagrams of CsBr-CaBr2 and KCl-CaBr2 show that the intermediate compound is formed. The results are in agreement with the computer prediction. Here, the various parts of the phase diagram of the quasiternary system CsBr-CaBr2-KCl were discussed.

Motivation effect of animated pedagogical agent's personality and feedback strategy types on learning in virtual training environment

Background The personality and feedback of an animated pedagogical agent(APA)are vital social-emotional features that render the agent perceptually believable.Their effects on learning during virtual training need to be examined.Methods In this paper,an explanation model is proposed to clarify the underlying mechanism of how these two features affect learners.Two studies were conducted to investigate the model.In Study 1,the effect of the APA's personality type and feedback strategy on flow experience and performance was reexamined,revealing significant effects of the feedback strategy on flow and performance and a marginally significant effect of the personality type on performance.To explore the mechanism behind these effects,a theoretical model is proposed by distinguishing between intrinsic and extrinsic motivation effects.In Study 2,the model was evaluated,and the APA's personality type was found to significantly influence the factors in the path of the extrinsic motivation effect rather than those in the path of the intrinsic motivation effect.Results In contrast,the feedback strategy affected factors in the path of the intrinsic motivation effect.Conclusions These results validated the proposed model.Further distinguishing the two motivation effects is necessary to understand the respective effects of an APA's personality and feedback features on learning experiences and outcomes.

A simple visual method for DNA detection based on the formation of gold nanoparticles

A simple visual method for DNA detection during the formation of gold nanoparticles(AuNPs) was developed based on different electrostatic properties of single strand DNA(ssDNA) and double strand DNA(dsDNA).Since the ssDNA is easy to bind to AuNPs due to its exposed bases which could prevent saltinduced aggregation of AuNPs.The dsDNA always present negative charge because its negatively charged phosphate backbone is exposed.In this case,the dsDNA could disturb the adsorption between dsDNA and AuNPs and result in non-aggregation of AuNPs.After hybridization,chloroauric acid and ascorbic acid were added to the mixture solution,and the solution changed to red immediately and turned to purple in10 min in the present of target DNA.TEM results confirmed that the change of color stemed from aggregation of AuNPs.In order to obtain accurate results by naked eye,the DNA detection assay should be conducted under pH 7.0.

An objective method for color vision deficiencies measurement based on visual evoked potential

The equi-luminance of color stimulus in normal subjects is characterized by L-cone and M-cone activation in retina. For the protanopes and deuternopes, only the activations of one relevant remaining cone type should be considered. The equi-luminance turning curve was established for the recorded visual evoked potentials (VEPs) of the luminance changes of the red and green color stimulus, and the position of the equi-luminance was used to define the kind and degree of color vision deficiencies. In the test of 47 volunteers we got the VEP traces and the equi-luminance turning curves, which was in accordance with the judgment by the pseudoisochromatic plate used in clinic. The method fulfills the objective and quantitative requirements in color vision deficiencies test.

Study of Unforced Unsteadiness in Centrifugal Pump at Partial Flow Rates

In order to explore the unforced unsteadiness of centrifugal pumps,a 2-D frequency domain imaging display technology was used to study the development of these unsteady flow structures at partial flow conditions.The results showed that,the unsteady flow field was not only affected by rotor and stator interaction,but also appeared an unforced unsteadiness with fundamental frequency of St≈0.23 around the impeller throat area.Moreover,as the flow rates decreased,this unsteady flow structure gradually weakened and disappeared.When the flow rate was reduced to 0.6 times of design flow rate,another two unforced unsteady flow structures with characteristic frequencies of St≈0.0714 and St≈0.12 began to appear in the same area.Therefore,with the operating condition smaller than design flow rate,the internal flow became more and more complex.In addition to the forced unsteadiness,the unforced unsteadiness which is not connected with the blade passage frequency became more and more obvious.

SEIR-SW, Simulation Model of Influenza Spread Based on the Small World Network

This study modeled the spread of an influenza epidemic in the population of Oran, Algeria. We investigated the mathematical epidemic model, SEIR（Susceptible-Exposed-Infected-Removed）, through extensive simulations of the effects of social network on epidemic spread in a Small World（SW） network, to understand how an influenza epidemic spreads through a human population. A combined SEIR-SW model was built, to help understand the dynamics of infectious disease in a community, and to identify the main characteristics of epidemic transmission and its evolution over time. The model was also used to examine social network effects to better understand the topological structure of social contact and the impact of its properties. Experiments were conducted to evaluate the combined SEIR-SW model. Simulation results were analyzed to explore how network evolution influences the spread of desease, and statistical tests were applied to validate the model. The model accurately replicated the dynamic behavior of the real influenza epidemic data, confirming that the susceptible size and topological structure of social networks in a human population significantly influence the spread of infectious diseases. Our model can provide health policy decision makers with a better understanding of epidemic spread,allowing them to implement control measures. It also provides an early warning of the emergence of influenza epidemics.