Some electrical and optical properties of copper-sodium-phosphate glasses

Abstract

In this paper it is proved that the dual of a code of order r + (r + 1 )_m,s which is a linear code over GF(2) obtained by annexing some vectors to the basis vectors of an rth order Reed-Muller code R(r, m), is a code of order (m ?r ?2) + (m ?r?1)_m,swhere Further, the weight distribution of such codes is obtained in some particular cases.     

On the Fundamental Tradeoff of Spatial Diversity and Spatial Multiplexing of MISO/SIMO Links with Imperfect CSIT

In this paper, we analyze the role of CSIT on the fundamental performance tradeoff for a MISO/SIMO link. Defining CSIT quality order as alpha = - log sigma² _Deltah / log SNR, we showed that using rate adaptation, one can achieve an average diversity order of d ^macr(alpha, r macr) = (1 + alpha - r macr)n where n is the number of transmit or receive antennas, r macr is the average multiplexing gain and alpha is the CSIT quality. We also showed that this diversity order is optimal for r macr isin [0.1 - alpha] and alpha < 1. The relationship suggests that imperfect CSIT can also provide additional diversity order and interpret the CSIT quality order as the maximum achievable spatial multiplexing gain with n diversity order.     

On extremal self-dual ternary codes of lengths 28 to 40

The extremal self-dual ternary codes of lengths 28, 32, and 36 with monomial automorphisms of prime order r⩾5 and of length 40 with monomial automorphisms of prime order r>5 are enumerated. For each length and prime considered, all inequivalent extremal codes with an automorphism of that order are found     

Device performances of third order micro-cavity green top-emitting organic light emitting diodes

Results on the device performances of 3rd order micro-cavity effects in green top emitting organic light emitting diodes (TEOLEDs) with optical spacer layer are reported. The performances of fabricated 3rd order micro-cavity green devices using fac-tris(2-phenylpyridine)iridium [Ir(ppy)₃] green phosphorescent emitter and magnesium silver alloy semi-transparent cathode are systematically compared with the 2nd order cavity device. The optical and electrical simulation results of the 3rd order cavity device with emissive layer (EML) located near the semi-transparent cathode shows a current efficiency (CE) of 71.0 cd/A (70% value of the 2nd order device) and more serious color coordinates shift as compared to the 2nd order cavity device. With the center EML positioned 3rd order cavity device similar color variation behavior is observed but the CE value is 73.8 cd/A (73% value of the 2nd order device). The fabricated 3rd order TEOLEDs exhibit about 65–75% CE values of the 2nd order device as the simulation. Additionally, the viewing angle characteristics are significantly improved in the 3rd order center EML TEOLEDs as the simulation. The performances of fabricated TEOLEDs with 3rd order micro-cavity conditions are in quite good agreement with the optical and electrical simulation results.     

Trap density of silicon chlorine oxides

By measuring the ramp voltage I–V characteristics, we obtained the oxide trap density and capture cross-section for (O₂ + HCl) dry oxidized samples in the temperature range 900–1100°C. It was found that the oxide trap density increases with an increase in the oxidation temperature. The activation energy of oxide trap incorporation is of the order of 4 eV. The capture cross-section determined for the oxide traps is of the order of 10⁻¹⁴ cm².     

Inkjet deposition of a hole-transporting small molecule to realize a hybrid solution-evaporation green top-emitting OLED

The QUPD molecule has been deposited by inkjet printing as a hole-transport layer in top-emitting green OLEDs. A systematic study of the QUPD-based ink formulation has been done and different solvent mixtures have been investigated, in order to find the best composition (QUPD in toluene/IPA/anisole, 8/1/1 v/v/v) leading to the best film forming properties. Spin-coated PEDOT-PSS has been used as hole injecting layer. Subsequent layers have been deposited by vacuum sublimation. The resulting hybrid, solution-sublimation, OLEDs have been encapsulated by atomic layer deposition using Al₂O₃ material. In order to overcome the issue related to the thickness control of the organic layers deposited from solution, second order cavity length OLEDs have been fabricated by modifying the n-doped electron transport layer thickness. In that case, the relative OLED efficiency variation (10.5%) due to the thickness variation is far less compared to first order cavity length (34%) allowing a better reproducibility of the OLED fabrication. In the end, high efficiency (18 lm/W) green OLEDs of two different sizes, 0.44 cm² and 4 cm², have been fabricated, using an inkjet printed QUPD layer as hole transporting layer.     

Phase coherence of optical waveguides

The effective refractive index of real waveguides is not constant, but fluctuates as a result of variations in composition and waveguide dimensions. Consequently, the accumulated phase during propagation has a component that undergoes a random walk and whose mean square increases with length 〈Δφ²〉=2L/L_coh. These phase fluctuations result in wavelength fluctuations in Mach-Zehnder interferometers, especially in interferometers of low order. By measuring these fluctuations for Mach-Zehnder interferometers of different order, we have verified the above relation and determined that L_coh≈27 m for our phosphorus-doped core silica on silicon waveguides     

A comparison of optoelectronic properties of lattice-matched andstrained quantum-well and quantum-wire structures

The k·p formalism is used to study the absorption spectra, material and differential gain in quantum wires as a function of orientation, built-in strain, and wire dimensions. The results for material and differential gain are compared with those for an optimized quantum-well structure. We find that for quantum wires at 300 K, the gain becomes positive at a carrier density of 1.27·10¹⁸ cm^-3, while in quantum wells this density is calculated to be 1.82·10¹⁸ cm^-3. Incorporating tensile strain in the wires reduces the transparency carrier concentration to 0.96·10¹⁸ cm^-3 while compressive strain allows one to obtain positive gain for densities greater than 1.08·10¹⁸ cm^-3. Orienting the wire along the [111] direction reduces the transparency carrier density to 0.60·10¹⁸ cm^-3. The differential gain in quantum-well structures for injections near the threshold is on the order of 10^-14 cm^-4, while for 50 Å·100-Å quantum wires the differential gain near the threshold is found to be on the order of 10^-13 cm^-4 . The differential gain in wires whose wire axis is parallel to the [111] direction has also been found to be on the order of 10^-13 cm^-4 for carrier injections close to the threshold     

Analysis of transmit antenna selection/orthogonal space‐time block coding with receive selection and combining in the presence of feedback errors

Examining the effect of imperfect transmit antenna selection (TAS) caused by the feedback link errors on the performance of hybrid TAS/orthogonal space‐time block coding (OSTBC) with single receive antenna selection (i.e., joint transmit and receive antenna selection (JTRAS)/OSTBC) and TAS/OSTBC (with receive maximal‐ratio combining‐like combining structure) over slow and frequency‐flat Nakagami‐m fading channels is the main objective of this paper. Under ideal channel estimation and delay‐free feedback assumptions, statistical expressions and several performance metrics related to the post‐processing signal‐to‐noise ratio are derived by defining a unified system model concerning both JTRAS/OSTBC and TAS/OSTBC schemes. Exact analytical expressions for outage probability (OP) and bit/symbol error rates of M‐ary modulations are presented in order to provide a detailed examination on the OP and error performances of the unified system that experiences feedback errors. Also, the asymptotic diversity order analysis, which shows that the diversity order of the investigated schemes is equal to the diversity order provided by OSTBC transmission itself, is included in the paper. Moreover, we have validated the theoretical results via Monte Carlo simulations. Copyright © 2014 John Wiley & Sons, Ltd.     

Delta Modulation of the Wiener Process

The analysis of the performance of a delta modulator with a Wiener process input is considered. The mean and the variance of the steady-state squared error are derived. In addition, the mean of the steady-state error of order four is calculated. It is shown that the behavior of all these moments as functions of the step size Δ and the sampling intervalTis similar: for each fixed Δ, the moments are monotonically increasing inT. More important, for each fixedT, there exists an optimal step size Δoptwhich minimizes each of these moments. It is shown that Δoptis a multiple ofT^{1/2}and that the corresponding minimum value of the moments is a multiple of eitherTor T², depending on the order of the moment.     

Spectroscopic study of high current discharges

A high current arc was developed between carbon electrodes in H2, SF6, He, Ar, and air at an initial pressure higher than 1 atm. The current peak was above 5 kA and the duration of the current was 250 µs. The temporal and spatial changes of plasma parameters were measured by time-resolved spectrography and high-speed framing camera. The electron density of the plasma was estimated from the Stark broadening of the lines, Hβ, C II 4267 Å, He I 4471 Å, and He I 5876 Å. Our observations show the following: The arc space is divided into two regions, the bright narrow core and the broad outer flame. The electron density of the core is estimated to be of the order of 10¹⁸cm^-3and an electron temperature of the order of 10⁴°K is obtained at current peak. Even after current zero, the electron density keeps the order of 10¹⁷cm^-3regardless of the kind of gas.     

Electrical and photovoltaic characteristics of indium-tin oxide/silicon heterojunctions

Measurements on indium-tin-oxide/Si heterojunctions indicate that the conduction band discontinuity at the interface, ΔE_c, is on the order of 0.45 eV for ITO with 9 mole-% SnO₂. This value is inappropriate for use of ITO/Si heterojunction cells for photovoltaic energy conversion. It is too large for ITO/p-Si cells and too small for ITO/n-Si devices. For either type of device the resultant built-in voltage is inadequate for high efficiency solar cells. The maximum solar conversion efficiencies obtained are on the order of 0.3%. These results are in disagreement with previous work on ITO/Si heterojunctions.     

A method of determining impurity diffusion coefficients and surface concentrations of drift transistors

In order to control the electrical parameters of drift transistors, it was found necessary to control the impurity concentration gradient in the base. An extension of the space charge widening theory provides a method of calculating this gradient, the surface concentration, and the diffusion coefficient. By this method, the diffusion coefficient of arsenic into germanium at 725°C was found to be 3.1 × 10^-12cm²/second and the initial surface concentration was of the order of 10²⁰atoms/cm³. Universal graphs for design calculations and rapid reference are presented.     

Low-frequency noise in gallium nitride epitaxial layers with different degrees of order of mosaic structure

The correlation between the noise level 1/f and the degree of mosaic-structure order in gallium nitride epitaxial layers was studied for the first time. Samples with a doping level of N _d ?N _a ≈8×10¹⁶ cm^?3 and a relatively high degree of order were characterized by the Hooge parameter α≈1.5×10^?3. This value is unprecedently low for thin GaN epitaxial films. The Hooge parameter was significantly higher for samples with N _d ?N _a ≈1.1×10¹⁸ cm^?3 and a low degree of order despite the fact that α generally decreases with increasing doping level at the same degree of order. Thus, the degree of mosaic-structure order affects not only the optical and electrical characteristics but also the fluctuation parameters of GaN epitaxial layers.     

Evaporated AgBr as a potential photosensitive material for the new lithographies

Evaporated AgBr films of the order of 2000 Å thick exhibit sensitivity of the order of 50 µJ/cm²at wavelengths between 2600 and 3000 Å, of the same order of magnitude at the X-ray wavelength of 7 Å, and sensitivity of the order of 10^-9to 10^-10C/cm²to electron-beam excitation at potentials ranging from a few to 25 kV. This sensitivity derives in part from the large absorption (or stopping power) and in part from the amplification or gain in the development process (∼10⁵). The resolution is shown to be dependent upon grain size but most importantly upon the development process. The development process, now under active study, limits the present resolution to the order of 1 µm. In principle, the ultimate resolution, coupled with high gain, should approach that attainable with emulsions, namely about 5000 line pairs/mm. The proposed method of using evaporated AgBr in a photoresist system involves the deposition onto a relatively thick polymer, chosen for its resist properties. Image transfer from the photographically generated Ag image to the resist polymer is by dry etching techniques.     

Surface electric fields and impedance matrix elements of stratifiedmedia

For the various geometrical configurations of waves in stratified media, we consider the important case when both source and field points are located on the same interface separating two different dielectric media. We denote this configuration as surface electric field case. In this paper, the electric fields are calculated numerically without using potentials. For the surface electric field case the integrand of the electric field grows with k_ρ^3/2 for large κ_ρ making the Sommerfeld integral singular. To calculate the surface electric fields in the spatial domain, we previously applied a technique of higher order asymptotic extraction. In the higher order asymptotic extraction, the higher order asymptotic parts were calculated analytically. The remainder, which has an integrand decays as κ_ρ^-3/2 was calculated numerically along the Sommerfeld contour path of integration. In this paper, we use a different extraction technique, the half-space extraction. After the half-space extraction, the integrand of the Sommerfeld integral of stratified media decays exponentially and the integral is calculated along the Sommerfeld integration path. The half-space extraction part is calculated by numerical integration along the vertical branch cuts. The surface electric fields for stratified media using half-space extraction and higher order asymptotic extraction are in good agreement. To validate the accuracy of the solution, we also compute the impedance matrix elements using surface electric fields, testing, and basis functions all in the spatial domain. The results are then compared with the results of the spectral domain method. The comparisons of the complex impedance matrix elements are tabulated and show that the difference is less than 2%     

利用傅氏变换全息图的非线性记录实现图象微分

提出一种图象边缘增强的新方法。仅简单地调整参考光和物光的光强比,记录一个非线性条件下的傅氏变换全息图,即可完成对图象的微分运算。从理论上分析了全息记录的非线性效应使得图象得到微分结果的原理。给出了实验结果。     

Analysis of diversity schemes employing antenna selection in the presence of channel estimation errors and feedback delay

The main objective of this paper is to provide an extensive and complete examination on the effect of practical impairments such as channel estimation errors (CEEs) and feedback delay (FD) on the performance of diversity schemes over Nakagami‐m fading channels. Under erroneous channel estimation and outdated feedback cases, statistical expressions and several performance metrics related to the post‐processing signal‐to‐noise ratio (SNR) are derived for four different diversity schemes: transmit antenna selection (TAS)/orthogonal space–time block coding, TAS/maximal‐ratio transmission (MRT), MRT/receive antenna selection (RAS), and joint transmit and RAS. Exact analytical expressions for outage probability and average error rates of M‐ary modulations are derived in order to provide insightful perspectives on the capacity and error performance of diversity schemes that experience both CEE and FD. The asymptotic diversity order of the investigated diversity schemes are derived via a high‐SNR approximation approach. In order to assess the real‐world performance of the investigated diversity schemes and to observe their robustness or sensitivities in practical imperfections, various configurations are considered together with several performance comparisons. Also, Monte Carlo simulations are performed in order to validate the theoretical results. Copyright © 2014 John Wiley & Sons, Ltd.     

Sort-and-match algorithm for soft-decision decoding

Let a q-ary linear (n, k) code C be used over a memoryless channel. We design a decoding algorithm Ψ_N that splits the received block into two halves in n different ways. First, about √N error patterns are found on either half. Then the left- and right-hand lists are sorted out and matched to form codewords. Finally, the most probable codeword is chosen among at most n√N codewords obtained in all n trials. The algorithm can be applied to any linear code C and has complexity order of n³√N. For any N⩾q^n-k, the decoding error probability P_N exceeds at most 1+q^n-k/N times the probability P_Ψ (C) of maximum-likelihood decoding. For code rates R⩾1/2, the complexity order q^n-k/2 grows as square root of general trellis complexity q^min{n-k,k}. When used on quantized additive white Gaussian noise (AWGN) channels, the algorithm Ψ_N can provide maximum-likelihood decoding for most binary linear codes even when N has an exponential order of q^n-k     

Diversity Analysis of Smart Relaying

It has been known that relaying can provide spatial diversity while satisfying the size-limited constraint of the users' devices in wireless communications systems. For a practically attractive decode-and-forward (DF) relaying system with maximal-ratio combining at the destination, spatial diversity is lost, except when the source–relay link is reliable. To deal with the problem and inspired by the work of Wang , this paper considers and analyzes an adaptive transmission scheme, which is referred to as smart relaying, when only the average relay–destination (R–D) signal-to-noise ratio (SNR) is available at the relay. In the system under consideration, the source continuously transmits the information to the destination. The relay adaptively scales its transmitted power to changes in the channel condition but never exceeds the total power that the conventional relaying used. Performance analysis proves that a diversity order of 2 is always obtained for binary phase-shift keying (BPSK) and quaternary phase-shift keying (QPSK). A diversity order of 2 is also observed for higher order rectangular quadratic-amplitude modulation (QAM) constellations through numerical results. The result on diversity order does not depend on how perfect the R–D feedback channel and how exact the quantization of the power scaling are. All the corresponding results of Wang are subsumed in our analysis.