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In fitting a power-law process, we show that the construction of the empirical recurrence rate time series either simplifies the modeling task, or liberates a point process restrained by a key parametric model assumption such as the monotonicity requirement of the intensity function. The technique can be applied to seasonal events occurring in spurts or clusters, because the autoregressive integrated moving average (ARIMA) procedure provides a comprehensive set of tools with great flexibility. Essentially, we consolidate two of the most powerful modeling tools for the stochastic process and time series in the statistical literature to handle counts of events in a Poisson or Poisson-like process. [ABSTRACT FROM PUBLISHER]

A physics-based SPICE model that takes into account the statistical impacts of both successive and progressive oxide breakdowns is presented to evaluate the time-dependent dielectric breakdown (TDDB)-induced performance degradation in static random access memory cells and peripheral circuits. The postbreakdown $I$ – V$ characteristics and the distribution of time to breakdown (t_{\rm {BD}}) have been verified against experimental data from 45-nm Silicon on insulator technology. We show that peripheral circuits, such as word-line driver, sense amplifier, and write driver, also contribute to degradation of performance during read and write operations. Using the model, the statistical impact of TDDB on sensing delay and write access time can be properly modeled for read and write failure prediction. [ABSTRACT FROM AUTHOR]

This paper analyzes the root cause of performance degradation and the impact of hot-carrier injection (HCI) on the lifetime prediction of an $LC$ voltage-controlled oscillator ( $LC$ -VCO). Observed from both constant voltage stress and ramped voltage stress tests, it is shown that the dominant degradation mechanism shifts from a negative bias temperature instability to an HCI due to the accelerated aging condition. Furthermore, simulations show that a frequency increase of degraded VCO is mainly attributed to the degradation in the pMOSFET of a cross-couple pair, while the degradations in the pMOSFET and nMOSFET have relatively the same impact on the startup voltage shift. Compared with the frequency change, the degradation of the startup voltage of an $LC$ -VCO is less sensitive to device width. Based on the observed results, methodologies to optimize the reliability tests and mitigate the frequency shift of $LC$ -VCO are proposed. [ABSTRACT FROM PUBLISHER]

Time-dependent dielectric breakdown (TDDB), in which the traps in oxide bulk form a conducting path under application of stress voltage for long period of time, has emerged as one of the important sources of performance degradation in advanced devices. In this paper, we give an overview of the recent progress in the understanding of ultra-thin dielectric breakdown in devices and consider its impact at the circuit-level. From the device point of view, the breakdown (BD) phenomenon, including the BD statistics, trap generation models, and BD evolution in ultra-thin dielectric are presented followed by the recent studies on TDDB in high- k metal gate (HKMG) devices and magnetic tunnel junction (MTJ) memories. On the circuit side, we explore methodologies for circuit lifetime assessment, the impact of TDDB on circuit performance degradation, and design techniques to improve circuit reliability. [ABSTRACT FROM AUTHOR]

Positive bias temperature instability (PBTI) has become one of the major reliability concerns in the present day CMOS technology. The PBTI mostly degrades the performance of high- \(\kappa \) /metal gate (HK/MG) nMOSFETs and is dominated by time dependent stress induced trap generation. The PBTI models proposed so far in different literature are deterministic in nature and overlook the randomness of the temporal degradation of transistor threshold voltage, \(V_{\rm th}\) . In this paper, we present a stochastic model for PBTI to predict the behavior of HK/MG nMOSFETs under inversion mode stress. The model is scalable and is verified against experimental data from two different groups. Our model separately considers each trap to predict their impact on device performance. The simulations are carried out at accelerated voltage and temperature conditions and we noted the variations in \(V_{\rm th}\) . In addition, we have analyzed the impact of PBTI on the performance of a ring oscillator and concluded that the circuit speed suffers significant degradation due to this effect. We have also observed that the adverse effect of PBTI becomes more severe as we go deeper into the nanometer technology. [ABSTRACT FROM AUTHOR]

In this paper, we present a physics-based SPICE model for statistical soft breakdown (SBD) in ultrathin oxide. Statistical SBD induces an increase in gate leakage current (IG{\_BD}) based on the time to breakdown (tBD) and the location of the percolation path in the channel. The proposed model has been validated with experimental data, and fed into circuit simulators to predict the degradation of device/circuit performance. Using the model, we analyzed the impact of the increased IG{\_BD} due to the first SBD on cell stability and performance in SRAM cells. We observed that IG{\_BD} variation due to SBD increases READ and WRITE failure probability, resulting in reduced lifetime. [ABSTRACT FROM PUBLISHER]

The electrical performance of low-temperature polysilicon (LTPS) thin-film transistors (TFTs) has improved considerably in the last decade, due to the flourishing active-matrix liquid crystal display industry. However, there is a need to further scale down LTPS TFT devices on flexible substrates to explore other application domains. In order to realize this goal, self-heating-induced negative bias temperature instability (NBTI) in LTPS TFTs needs to be modeled to determine its effect on transistor degradation and to develop mitigation techniques. Although the characteristics of NBTI for TFTs are widely known, the effects of device geometry and substrate on temperature-dependent NBTI have not been considered. In this paper, for the first time, a self-consistent electrothermal model that considers the effects of device geometry, substrate, and stress conditions on NBTI is proposed. With the proposed modeling methodology, we show the significant impact of device geometry, substrate, and supply voltage on NBTI in LTPS TFTs. [ABSTRACT FROM AUTHOR]

Abstract: There have been a lot of reports about the fact that the characteristics of datasets will strongly affect the performance of different classifiers. A study in the cognition is thus conceived, and it is natural to propose the Bayesian approach. As is well known, valuable quantitative features from datasets are easily captured and then to update these previous classification problems to guarantee well class separability. The purpose of this learning method is to give an attractive pragmatic feature of the Bayesian approach in the quantitative description of class imbalance problem. Thus, a programming problem of mixing probability information: Bayesian Support Vector Machines (BSVMs) is discussed. In addition, we first change some of the aims and conditions of the original programming problems and then explore what effect will be acquired due to the change. The experiments on several existing datasets show that, if prior distributions are assigned to the programming problem, the estimated classification errors will be reduced. [Copyright &y& Elsevier]

Abstract: The volcanic activity of Avachinsky is assumed to follow a Poisson process and is fingerprinted with a sequence of empirical recurrence rate time series. The last 5 time series are used as a prediction set to check the predictive ability of the candidate model produced by time series modeling techniques. The model is used to forecast future recurrence rates that, in turn, are used to develop the mean function of the volcanic process, which is required to evaluate the probability of future eruptions. At the model validation stage, the candidate model forecasts a mean number of 2.31 eruptions for the prediction set that are close to the actual number of events, which are 2 eruptions. For a full scaled forecast, the model concludes a total of 2.37 new events for the next 25 years for the Avachinsky volcano. [Copyright &y& Elsevier]

In this paper, the feasibility of a low-temperature polysilicon (LTPS) microscale energy harvester for a wireless sensor node is investigated. For that purpose, two device-level models for the LTPS solar cell and thin-film transistors are proposed and employed in system-level evaluation of an energy harvesting system. The results of our analysis indicate that: 1) the maximum power operating point for the solar cell is different when connected to a lossy power converter; 2) increasing the average grain size of the LTPS film can reduce the circuit area by 20 times, while increasing the output power by 6%; and 3) the proposed bottom–up approach enables the designers to identify system bottlenecks and improve the performance accordingly. [ABSTRACT FROM AUTHOR]

Micro‐light‐emitting diodes (Micro‐LEDs) based on gallium nitride (GaN) materials offer versatile platforms for various applications, including displays, data communication tools, photodetectors, and sensors. In particular, the introduction of Micro‐LEDs in the optoelectronic industry enables the development of novel short‐distance wireless communication applications for the Internet of Things as well as near‐to‐eye displays for virtual reality and augmented reality. Micro‐LEDs used in conjunction with colloidal quantum dots (QDs) as color‐conversion layers provide efficient full‐color displays as well as white LEDs for high‐speed visible light communications (VLCs). Here, the latest progress on full‐color Micro‐LED displays with a printed QD color conversion layer, GaN material‐based Micro‐LEDs for VLC systems, and the photostability of novel QD materials for Micro‐LEDs is comprehensively reviewed. Outlooks on the efficiency of Micro‐LEDs with sizes ≤10 µm, QD stability issues, and flexible Micro‐LED displays are also provided. [ABSTRACT FROM AUTHOR]

Polarizers play a key role in generating polarized light for display, imaging, and data communication, but adoption often suffers from high optical loss. Recently, due to superior optoelectronic properties, halide perovskites have been widely developed for lighting applications; however, highly polarized emission (polarization degree >0.8) has not yet been realized with perovskites. Herein, by incorporating inkjet printing and an anodic aluminum oxide (AAO) confinement strategy, highly ordered perovskite nanowire (NW) arrays are demonstrated for anisotropic optical applications. The optical device based on perovskite NW arrays reveals a high photoluminescence external quantum efficiency of 21.6% and emits highly polarized light with polarization degree up to 0.84. The highly polarized emission from perovskite NW arrays has potential to considerably reduce the optical loss of polarizers, which may attract great interest in developing polarized light sources for next‐generation optoelectronic applications. [ABSTRACT FROM AUTHOR]

Tissue expander breast reconstruction is a common post mastectomy breast procedure performed by plastic surgeons. The purpose of this study was to define the incidence of breast reconstruction prosthetic infection, relate patient characteristics with increased rate of infection, and analyze the influence of postoperative complications to expander/implant infection. A retrospective, single-institution chart review of 195 women with post mastectomy tissue expander/implant reconstructions performed from 2006 through 2008 was conducted. Total periprosthetic infection rate was calculated. Patient factors, operative technique, and noninfectious complications were analyzed and related to increased periprosthetic infection rate. A binary logistic regression model was fitted using periprosthetic infection as the dependent variable and 12 patient characteristics as independent variables, followed by a step-wise model for best fit with a limited number of independent variables. The overall periprosthetic infection rate per patient over the 2 year period was 5.1%. The incidence of periprosthetic infection per reconstructed breast was 3.2%. Odds ratio estimates indicated that the presence of cellulitis increased the odds of periprosthetic infection more than 200 times (p = <0.0001), and inpatient procedures increased the odds 16 times (p = 0.02). Other variables (i.e., age > 65, DM, flap necrosis, smoking, dehiscence, AlloDerm, etc) failed to reach statistical significance (p > 0.05). Postoperative breast cellulitis and inpatient status appear to be significant risk factors for increased periprosthetic infection. No significant increase in periprosthetic infection rate was noted with other variables in this model. [ABSTRACT FROM AUTHOR]

Single-ZnO-nanowire (NW) memory based on resistive switching is demonstrated for the first time. The NW memory is stable, rewritable, and nonvolatile with on/off ratio up to \7.7 \times \10^5. The O vacancies at the surfaces of ZnO NWs and around the interface of Ti/ZnO NWs observed using X-ray phototelectron spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction, and high-resolution TEM might play a role in the resistive switching behavior. The endurance of resistive switching can be enhanced by further increasing the sweeping voltage. This paper brings an exciting possibility of building next-generation memory devices based on NWs. [ABSTRACT FROM AUTHOR]

Objectives: Although uncommon, prolonged postoperative air leaks are a troublesome complication of lung surgery. This study was performed to determine if buttressing pulmonary staple lines would reduce air leakage at varying airway pressures, and if there was a difference between buttressing materials.Methods: Using cadaver lungs, the development of air leak from staple lines was evaluated at incremental airway pressures. Unreinforced staples were compared to staples reinforced with bovine pericardium and staples reinforced with expanded polytetrafluorethylene (ePTFE).Results: Unreinforced staple lines began to leak air at an airway pressure of 20 mm Hg, and > 90% leaked at a pressure of 35 mm Hg. Both bovine pericardium and ePTFE significantly reduced the incidence of air leak at these airway pressures. At higher airway pressures, ePTFE was superior to bovine pericardium.Conclusion: Staple line reinforcement with either material protects against air leak. Patients at risk for elevated airway pressures and/or postoperative ventilator support should be considered for utilization of these staple reinforcing materials. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (PQDs) are a competitive candidate for next‐generation display technologies as a result of their superior photoluminescence, narrow emission, high quantum yield, and color tunability. However, due to poor thermal resistance and instability under high energy radiation, most PQD‐based white light‐emitting diodes (LEDs) show only modest luminous efficiency of ≈50 lm W−1 and a short lifetime of <100 h. In this study, by incorporating cellulose nanocrystals, a new type of QD film is fabricated: CH3NH3PbBr3 PQD paper that features 91% optical absorption, intense green light emission (518 nm), and excellent stability attributed to the complexation effect between the nanocellulose and PQDs. The PQD paper is combined with red K2SiF6:Mn4+ phosphor and blue GaN LED chips to fabricate a high‐performance white LED demonstrating ultrahigh luminous efficiency (124 lm W−1), wide color gamut (123% of National Television System Committee), and long operation lifetime (240 h), which paves the way for advanced lighting technology. [ABSTRACT FROM AUTHOR]