Error Tolerant DNA Self-Assembly Using ( $hbox{2}k-hbox{1}$)$times$( $hbox{2}k-hbox{1}$) Snake Tile Sets

DNA self-assembly has been advocated as a possible technique for bottom-up manufacturing of scaffolds for computing systems in the nanoscale region. However, self-assembly is affected by different types of errors (such as growth and facet roughening) that severely limit its applicability. Different methods for reducing the error rate of self-assembly using tiles as basic elements have been proposed. A particularly effective method relies on snake tile sets that utilize a square block of even size (i.e., 2k times 2k tiles, k = 2, 3,.. .). In this paper, an odd-sized square block [i.e., (2k -1) times (2k - 1)] is proposed as basis for the snake tile set. Compared with other tile sets, the proposed snake tile sets achieve a considerable reduction in error rate at a very modest reduction in growth rate. Growth and facet roughening errors are considered and analytical results are presented to prove the reduction in error rate compared with an even-sized snake tile set. Simulation results are provided.     

Measuring $I/Q$ Impairments in WiMAX Transmitters

This paper presents a new method for measuring the I /Q impairments affecting the worldwide interoperability for microwave access (WiMax) transmitters through the analysis of the signal acquired through a general-purpose I /Q receiver. Based on a model of the effects of the I /Q impairments on the output signal that is suitable for orthogonal frequency-division multiplexing (OFDM) systems like WiMax, the method is designed to correctly take into account the peculiarities of systems compliant with the IEEE 802.16-2004 standard, such as the potentially noxious effects of the impairments on signal normalization and threshold decisions. The results of the experiments carried out on the standard-compliant signals are given.     

Measuring Time-Varying $I/Q$ Impairments in Digital Transmitters

Impairments affecting the baseband modulator of digital transmitters, which are commonly called I/Q impairments, are responsible for the deviations of symbols from their original position on the I/Q diagram. They cause a reduction in the noise margin and ultimately worsen the probability of error. This is why their measurement is so important in all stages in the life cycle of digital transmitters. This paper presents an original method for the evaluation of the I/Q impairments based on a discrete extended Kalman filter (DEKF). In the same way as alternative solutions already presented in the literature, the method exhibits good performance in the presence of time-invariant impairments. Differently from them, it allows accurate measurements of time-varying impairments, thus making real-time tracking of their evolution feasible. After a few theoretical notes on the I/Q impairments and DEKF, the operative stages of the proposed method are described in detail. Several experiments are then conducted on radio frequency signals to assess the performance of the method; the obtained results are given and discussed.     

A $t$-Norm-Based Fuzzy Approach to the Estimation of Measurement Uncertainty

From a metrological point of view, a measurement process rarely consists of a direct measurement but, rather, of digital signal processing (DSP) performed by one or more instruments. The measurement algorithm makes the numerical results available as functions of acquired samples from input signals. Moreover, when repeated direct measurements are performed, one may speak about interactions in subsequent results (and it may be dependent on the type of instrument being used). With mathematical formalism, the complex relations involved can be described, although again, an indirect measurement result would be obtained. Regardless, no matter what kind of process is being examined, the distribution of the uncertainty associated with the measurement needs to be known. To express a measurement result with its associated uncertainty, the recommendations of the ISO Guide need to be met. Many published papers have proposed the use of fuzzy intervals to describe both the systematic and statistical effects of repeated measurements on the distribution of their results. In this paper, we use a random-fuzzy model, the single measure is represented as a fuzzy set, and the propagation of the possibility distribution through the DSP stage (which simply consists of an average operation) is performed using the extension principle of Zadeh based on a particular triangular norm: the so-called Dombi's.     

Measurement of Passive $R$, $L$, and $C$ Components Under Nonsinusoidal Conditions: The Solution of Some Case Studies

This paper deals with the measurement of the R, L, and C parameters of passive components in nonsinusoidal conditions. Since these components usually work with voltage and current waveforms that are different from sinusoidal ones, nonsinusoidal characterization has to be made. The importance of nonsinusoidal characterization of passive components is highlighted through the analysis of two case studies: (1) the influence of distorted waveforms on the line impedance stabilizer network (LISN) passive component behaviors and (2) the influence of voltage and current harmonics on hybrid filter responses. In this paper, the authors propose and describe a measurement method based on linear system identification and model parameter estimation techniques. Then, the two case studies are analyzed and described with the help of some test results.     

A $di/dt$ Compensation Technique in Delay Testing by Disconnecting Power Pins

Scan-based delay testing increases power consumption, particularly peak power, due to excessive simultaneous signal switching. The instantaneous current changes increase the ground level during signal switching, slowing down the operational speed. When the switching activity increases during test operations, it is necessary to pay special attention to determine whether the speed failures are due to extra switching, since the blind application of delay testing can greatly affect the yield of a device. This paper demonstrates that cycle time adjustment is best suited to compensate for the timing issues resulting from the higher switching activity in delay testing. In the proposed method, the power pins are disconnected in an increasing number to find a proper level of cycle period adjustment. The power pins of a chip are experimentally disconnected to observe the ground bounce behavior, which is also demonstrated in simulations. The experimental results also demonstrate that the proposed method can avoid the problem of abandoning good devices by cycle adjustment.     

On the Calibration of DA Converters Based on $R/beta R$ Ladder Networks

In this paper, we discuss the possibility of realizing high-accuracy digital-analog(DA) converters by exploiting the properties of R/betaR (beta > 2) ladder networks. Extensive simulations demonstrate that, if a proper value of beta is chosen, high accuracy can be obtained by resorting to a very simple self-calibration algorithm. This is true, even in the case of large tolerance values for the resistors that make up the ladder network. Such a result may allow the design of a high-accuracy very low cost converter. The effect of the offset of the comparator needed for the self-calibration algorithm is also discussed.     

The Refinement of Models With the Aid of the Fuzzy $k$ -Nearest Neighbors Approach

In this paper, we propose a new design methodology that supports the development of hybrid incremental models. These models result through an iterative process in which a parametric model and a nonparametric model are combined so that their underlying and complementary functionalities become fully exploited. The parametric component of the hybrid model captures some global relationships between the input variables and the output variable. The nonparametric model focuses on capturing local input-output relationships and thus augments the behavior of the model being formed at the global level. In the underlying design, we consider linear and quadratic regression to be a parametric model, whereas a fuzzy $k$-nearest neighbors model serves as the nonparametric counterpart of the overall model. Numeric results come from experiments that were carried out on some low-dimensional synthetic data sets and several machine learning data sets from the University of California-Irvine Machine Learning Repository.      

Comparison of the ${mbi A}^{*}{-}{mbi A}$ and ${mbi T}, Phi{-}Phi$ Formulations for the 2-D Analysis of Solid-Rotor Induction Machines

We present two eddy-current field potential formulations to solve rotating electrical machine problems by applying the finite-element method (FEM) using the motional ${mbi A}^{*}{-}{mbi A}$-potential formulation and the motional ${mbi T}, {bf Phi}{-}{bf Phi}$-potential formulation. We use the single-phase and three-phase solid-rotor induction motors of Problem No. 30a of TEAM Workshops to compare the potential formulations. We have solved both problems in the time domain and the frequency domain.      

量子点激光器及其应用研究

报道了分子束外延生长出自组装垂直耦合ＩｎＡｓ／ＧａＡｓ大功率量子点激光器材料和器件。对腔长为８００μｍ,室温下和７７Ｋ下边续激射阈值电流密度分别为２１８Ａ／Ｃｃｍ＾２和４９Ａ／ｃｍ＾２,波长为９６０ｎｍ,最大输出功率大于１Ｗ。首次报道在０．５４Ｗ工作下,寿命超过３０００小时,功率仅下降０．４９display status０     

Spin Seebeck Effect in Ni$_{81}$Fe$_{19}$/Pt Thin Films With Different Widths

The spin Seebeck effect (SSE) has been measured in Ni $_{81}$Fe $_{19}$ thin films which have different widths by using the inverse spin Hall effect (ISHE) in a Pt wire. The ISHE voltage induced by SSE is enhanced by lengthening the Pt wire. Combined with ISHE, SSE is applicable to the production of electric generators in which the thermoelectric figures of merit are tunable in terms of device structure.      

A 1.2-V CMOS $RC$ Oscillator for Capacitive and Resistive Sensor Applications

An accurate self-adjusting CMOS $RC$ oscillator for capacitive and resistive sensor applications has been designed and manufactured. The oscillator operates with supply voltages from 1.2 to 3 V and achieves an internal accuracy of $pm$ 0.7% with a temperature range from $-20 ^{circ}hbox{C}$ to 60 $^{circ}hbox{C}$. The $RC$ oscillator was fabricated in a 0.35- $muhbox{m}$ standard n-well CMOS process with threshold voltages of 0.5 and $-$0.65 V. Its design and operation are described, and results of measurements performed on the fabricated chips are presented.      

Circuit-Coupled ${bf t}_{0}hbox {-}phi$ Formulation With Surface Impedance Condition

A finite-element formulation based on the use of magnetic scalar potential is proposed. It allows to describe circuit-coupled electromagnetic formulation using magnetic scalar potential in presence of multiply connected solid conductors (with holes), treated by surface impedance condition. This formulation offers powerful solutions at a low cost. An example of application is given.     

Temperature and Excitation Dependence of Photoluminescence Spectra of InAs/GaAs Quantum Dot Heterostructures

In this study we investigated the effects that the carrier dynamics have on the temperature- and excitation-intensity- dependent photoluminescence (PL) spectra of a self-assembled quantum dot heterostructure. A rate equation model is proposed to take into account the dot size distribution, the random population of density of states, state filling effects, and the important carrier transfer mechanisms for the quantum dot system, including carrier capture, relaxation, thermal emission, and retrapping. This model reproduces the PL spectra quite well. Our quantitative calculations of the behavior of the thermal emitting carriers under various incident power intensities within the temperature range 15 K-240 K explain the carrier transfer process quite reasonably for the quantum dot system. In addition, we discuss the thermal redistribution and state filling effects in detail in our analysis of the dependence of the PL spectra on the temperature and excitation power intensity applied to the sample. Index     

The Use of Microdisk Lasers Based on InAs/InGaAs Quantum Dots in Biodetection

Technical Physics Letters - It is demonstrated that microdisk lasers about 10 μm in diameter with an active region based on InAs/InGaAs quantum dots synthesized on GaAs substrates can be used...     

Design and Characterization of a Sampling System Based on $Sigma$–$Delta$ Analog-to-Digital Converters for Electrical Metrology

This paper describes a sampling system designed using a commercial sigma–delta analog-to-digital converter ($Sigma$–$ Delta$ ADC). In addition to characterization measurements using a conventional high-quality signal generator, a Josephson waveform synthesizer that provides ultimately noise- and drift-free voltages was used. To evaluate the suitability of this sampling system as part of a transfer power standard, additional comparisons of the root-mean-square (RMS) values measured were performed against a thermal converter and the primary power sampling standard at the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany. Initial analysis of the measurement data shows an effective resolution in the range of 18–19 bits at an equivalent sampling rate of 64 kHz. The integral nonlinearity error of the system was measured to be within $pm 7 mu hbox{V/V}$ or one least significant bit at this resolution.      

Selective Intermixing of InAs/InGaAs/InP Quantum Dot Structure With Large Energy Band Gap Tuning

Selective postgrowth band gap tuning of self-assembled InAs/InGaAs/InP quantum dot (QD) structures has been investigated. Very large band gap blueshift of over 158 meV of the InAs QD structure has been received through the intermixing by exposing the sample under argon plasma and followed by thermal annealing at 780 °C. Selective intermixing of the InAs QD structure has been studied by depositing a $hbox{SiO}_{2}$ mask layer on the sample for the intermixing. The largest selective band gap shift between the $hbox{SiO}_{2}$ covered and uncovered regions of the sample reaches 77 meV. This intermixing selectivity decreases when the annealing temperature is increased. This reduction in the intermixing selectivity is attributed to the enhanced QDs intermixing of the $hbox{SiO}_{2}$-masked samples because of the out diffusion of different elements from the InAs/InGaAs/InP QD structure into the $hbox{SiO}_{2}$ cover layer. Three different energy band gap shifts of an InAs/InGaAs/InP QD structure across the wafer have been received by this postgrowth selective intermixing. The selective band gap tuning paves a way for monolithic integration of passive and active optoelectronic devices in QD systems.