A faster numerical method based on FDTD for the four energy level atomic system is present here. The initial conditions for the electrons of each level are achieving while the fields are in steady state. Polarization ...
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A faster numerical method based on FDTD for the four energy level atomic system is present here. The initial conditions for the electrons of each level are achieving while the fields are in steady state. Polarization equation, rate equations of electronic population and Maxwell’s equations were used to describe the coupling between the atoms and electromagnetic wave. Numerical simulations, based on a finite-difference time-domain (FDTD) method, were utilized to obtain the population inversion and lasing threshold. The validity of the model and its theory is confirmed. The time, which we can observe the lasing phenomenon, is much shorter in our new model. Our model can be put into using in large scale simulations in mutiphysics to reduce the total simulated time.
A new uniplanar printed PIFA with a coupled-feed structure for LTE/WWAN operation is proposed. The PIFA consists of a coupled-feed loop structure and two separated radiators which are able to generate additional bands...
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A new uniplanar printed PIFA with a coupled-feed structure for LTE/WWAN operation is proposed. The PIFA consists of a coupled-feed loop structure and two separated radiators which are able to generate additional bands for the operation. The loop antenna path and the longer radiator can produce a dualresonance generating the required lower band exactly, while three wide bands contributed by the loop path, the loop path with the longer radiator and the loop path with the shorter radiator can form an operating band to cover the(1710–2690 MHz) band. Because of the small size of only 14×70 mm2, the antenna which can cover the required eight bands is therefore very suitable for the modern Ultra-thin laptops.
Due to the semantic gap between low-level visual feature and high-level semantic concept, image annotation plays an important role in image retrieval. In this paper, an automatic image annotation approach using semant...
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Large touch screen systems (LTSS) have been widely used in scientific, industrial, educational and artistic domains. They are easy and natural for people to use. We present a novel touch screen interaction with finger...
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FRC technology mainly uses the visual inertia of human eyes which can be regarded as persistence of vision phenomenon by sequential frames. It is especially important to make the 6 bit panel display abundant colors. T...
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Beijing has experienced a rapid urban sprawl over the past three decades, along with accelerated socio-economic development. This study investigated the change patterns and figured out the driving forces of urban expa...
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ISBN:
(纸本)9783037857427
Beijing has experienced a rapid urban sprawl over the past three decades, along with accelerated socio-economic development. This study investigated the change patterns and figured out the driving forces of urban expansion in the study area. To obtain urban class, decision tree classification techniques were used to identify the land cover types using four scenes of Landsat images from four periods of 1978-era, 1992-era, 2000-era and 2010-era. Then, the urban areas were identified by excluding water, agriculture, forest, grassland and bare land. The analysis results showed that: 1) urban construction land had been expanded very quickly and the urban area is mainly in the south-central part of the municipality;2) the urban area increased by 96284.97 ha and the ratio was 5.88%;and 3) population growth, economic development, urban construction and industrial structure adjustment could explain the expansion. These analysis results can provide significant information on the monitoring and management of sustainable urban development.
Increasing number of research activities and different types of studies in brain-computer interface systems (BCIs) show potential in this young research area. However, BCIs have not become widely applied, most of them...
Increasing number of research activities and different types of studies in brain-computer interface systems (BCIs) show potential in this young research area. However, BCIs have not become widely applied, most of them are still limited in the laboratory and off-line. One of the important reasons is that: EEG signal acquisition is completed by the professional medical equipments. They are expensive and the parameters of them cannot be flexiblely changed with the specific BCI experiment paradigm. In the paper, a single-channel low-cost circuit of EEG signal acquisition for the BCI system is designed. The circuit is composed of protection circuit, instrumentation amplifier, common mode rejection (CMR) circuit, gain adjustable amplifiers and filters. In order to test this circuit, the circuit simulation and the real-time EEG measurements are implemented. The experimental results show that the circuit is effective with good performance, it is very suitable for the online BCI system.
When using Fresnel phase hologram for holographic projection display, the visual impression of reconstructed image is disturbed by zero-order beam because of pixelated Spatial Light Modulator (SLM). In order to elimin...
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When using Fresnel phase hologram for holographic projection display, the visual impression of reconstructed image is disturbed by zero-order beam because of pixelated Spatial Light Modulator (SLM). In order to eliminate the influence of zero-order beam, an imaging lens is placed in the back of SLM based on the existing Fresnel holographic projection system. In the back focal plane of the lens, high-pass filter is set on to eliminate the zero-order beam. By adding diverging spherical phase to the hologram, the phase transformation effect of the imaging lens is seen to cancel. Thus the purpose of adjusting the imaging position of the reconstructed image is achieved. A holographic projection system based on Liquid Crystal on Silicon (LCOS) has been developed. The experimental results indicate that the zero-order beam impact on holographic reconstruction has been eliminated effectively without changing the distance holographic reconstruction by Fresnel phase hologram.
In order to solve the problem that the iterative method for Linear Projection- Based Non-negative Matrix Factorization (LPBNMF) is complex, a method, called Linear Projective Non-negative Matrix Factorization (LP-NMF)...
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Video summarization provides condensed and succinct representations of the content of a video stream. A static storyboard summarization approach based on robust low-rank subspace segmentation is proposed in this paper...
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