QoS enhancement in OFDM based systems under transceiver impairments

Broadband wireless systems generally use orthogonal frequency division multiplexing (OFDM) with link adaptation (LA) to achieve high throughput while meeting bit error rate (BER) constraint. OFDM systems are known to be affected by non-linearity of high power amplifier (HPA) at transmitter, carrier frequency offset (CFO), symbol timing offset (STO) and channel estimation error at the receiver. The delay in feedback of channel state information (CSI) further affects the performance of LA procedures. The focus of this work is on performance analysis in presence of simultaneous affect of all these impairments on LA based OFDM systems. The results are found to be useful for threshold readjustment which is essential for successful implementation of LA scheme to counter the effects of change in operating conditions from ideal to as listed above.     

Exact Gaussian expansions of Slater-type atomic orbitals

Three exact Slater-type function (STO) integral transforms are presented. The STO-NG basis set can then be developed using either only 1s Gaussian functions, the same Gaussian exponents for each shell, or using the first Gaussian of each symmetry. The use of any of these three alternatives depends only on appropriate numerical integration techniques.     

Calculation of electron wave functions and refractive index of Ne

The radial wave functions of inner electron shell and outer electron shell of a Ne atom were obtained by the approximate analytical method and tested by calculating the ground state energy of the Ne atom. The equivalent volume of electron cloud and the refractive index of Ne were calculated. The calculated refractive index agrees well with the experimental result. Relationship between the refractive index and the wave function of Ne was discovered. Supported by the New Star Program of Beijing Science and Technology, China (Grant No. 952870400), the Beijing Municipal Commission of Education, and the Excellent Young Teachers Program of Ministry of Education, China     

Even-tempered Slater-type orbitals revisited: from hydrogen to krypton

Even-tempered Slater-type orbital basis sets were developed in 1973, based on total atomic energy optimization. Here, we revisit ET STOs and propose new sets based on past experience and recent computational studies. From preliminary atomic and molecular tests, these sets are shown to be very well balanced and to perform, at lower cost, almost as well as a very large (close to complete) basis set.     

The preparation of c-axis epitaxial Bi-2212 films on STO(1 0 0) by sol-gel method

Bi₂Sr₂Ca₁Cu₂O_8+δ (Bi-2212) films were grown on (1 0 0) oriented SrTiO₃ (STO) substrate using sol-gel spin-coating method. The effects of heat treatment conditions and coating times on the phase formation and surface morphology were investigated using thermal analysis, optical microscope, X-ray diffraction, and scanning electronic microscopy. Mixed phases were formed from 820 to 840 °C, and Bi-2212 single phase was obtained at 830 °C for 3 h. c-axis epitaxial films with smooth surfaces were obtained by drying at 600 °C and coating for 5 times.     

SrTiO3金属-绝缘体-半导体结构的介电与界面特性

采用金属有机分解法在p型Si衬底上制备了SrTiO3（STO）薄膜.研究了STO薄膜金属 绝缘体 半导体(MIS)结构的介电和界面特性.结果表明，STO薄膜显示出优异的介电性能，在10kHz处的介电常数约为105，损耗低于001，这来源于多晶结构和良好的结晶性；MIS结构中的固定电荷密度Nf和界面态密度Dit分别约为15×1012cm-2和(14—35)×1012cm-2eV-1，这主要与Si/STO界面处形成的低介电常数界面层有关. 关键词： SrTiO3薄膜 MIS结构 介电性能 Si/STO界面     

Riemannian three dimensional molecular spaces

A simple manipulation of the first order density function permits to define a curved 3D Riemannian coordinate set, which can substitute the usual flat 3D Cartesian space, where atoms and molecules are supposed to exist. Several simple models are discussed. Gaussian type orbitals generate a space division with positive and negative curvatures, the later one being near the centre of the functions; contrarily Slater type orbitals provide a positive curvature everywhere.     

Performance of revised STO(1M)-3G basis set for prediction of 5-fluorocytosine chemical shifts

Nuclear shieldings and chemical shifts of 5-fluorocytosine (5FC) were predicted in the gas phase and DMSO solution modeled by polarizable continuum model using B3LYP density functional and revised STO(1M)-3G basis set. For comparison, eight arbitrary selected basis sets including STO-3G and medium-size Pople-type and larger dedicated Jensen-type ones were applied. The former basis sets were significantly smaller, but the calculated structural parameters, harmonic vibrational frequencies, were very accurate and close to those obtained with larger, polarization-consistent ones. The predicted ¹³C and ¹H chemical shieldings of 5FC and cytosine, selected as parent molecule, were acceptable (root mean square for ¹³C chemical shifts in DMSO of about 5 ppm and less) though less accurate than those calculated with large basis sets, dedicated for prediction of nuclear magnetic resonance parameters.     

Wide band-response laser-induced thermoelectric voltage in tilted orientation SrTiO3 single-crystal coated by La0.7Sr0.3CoO3 layer

With different wavelengths from the infrared (IR) to ultraviolet (UV) band, laser-induced thermoelectric voltage (LITV) has been observed in the vicinal cut SrTiO₃ (STO) single crystals, coated with La_0.7Sr_0.3CoO₃ (LSCO) layer. It is demonstrated that the polarity of voltage signal in the STO substrate is reversed when the STO substrate is illuminated by UV laser rather than by IR or visible laser. The polarity of voltage signal in LSCO film is always consistent with that from the STO substrate no matter 1064 or 355 nm laser irradiate the LSCO film or the STO substrate. A possible interpretation of the phenomenon is proposed.