We considered the problem of forecasting the degradation recovery process of civil structures for prognosis and health management. In this process, structural health degrades over time but recovers when a maintenance intervention is performed. Maintenance interventions are typically recorded in terms of date and type. Such records can be represented as binary time series. Using binary maintenance intervention records, we forecast the process by using Long Short-Term Memory (LSTM). In this study, we experimentally examined how to feed binary time series data into LSTM. To this end, we compared the concatenation and reinitialization methods. The former is used to concatenate maintenance intervention records and health data and feed them into LSTM. The latter is used to reinitialize the LSTM internal memory when maintenance intervention is performed. The experimental results with the synthetic data revealed that the concatenation method outperformed the reinitialization method.

We investigated the photochemical stability of an electro-optic (EO) polymer under laser irradiation at 1310nm to reveal photodegradation mechanisms. It was found that one-photon absorption excitation assisted with the thermal energy at the temperature is involved in the photodegradation process, in contrast to our previous studies at a wavelength of 1550nm where two-photon absorption excitation is involved in the photodegradation process. Thus, both the excitation wavelength and the thermal energy strongly affect to the degradation mechanism. In any cases, the photodegradation of EO polymers is mainly related to the generation of exited singlet oxygen.

Aiming at the problem of the deterioration of the contact performance caused by the wear debris generated during the fretting wear of the electrical connector, low-frequency fretting wear experiments were carried out on the contacts of electrical connectors, the accumulation and distribution of the wear debris were detected by the electrical capacitance tomography technology; the influence of fretting cycles, vibration direction, vibration frequency and vibration amplitude on the accumulation and distribution of wear debris were analyzed; the correlation between characteristic value of wear debris and contact resistance value was studied, and a performance degradation model based on the accumulation and distribution of wear debris was built. The results show that fretting wear and performance degradation are the most serious in axial vibration; the characteristic value of wear debris and contact resistance are positively correlated with the fretting cycles, vibration frequency and vibration amplitude; there is a strong correlation between the sum of characteristic value of wear debris and the contact resistance value; the prediction error of ABC-SVR model of fretting wear performance degradation of electrical connectors constructed by the characteristic value of wear debris is less than 6%. Therefore, the characteristic value of wear debris in contact subareas can quantitatively describe the degree of fretting wear and the process of performance degradation.

Multi-cycle Test looks promising a way to reduce the test application time of POST (Power-on Self-Test) for achieving a targeted high fault coverage specified by ISO26262 for testing automotive devices. In this paper, we first analyze the mechanism of Stuck-at Fault Detection Degradation problem in multi-cycle test. Based on the result of our analysis we propose a novel solution named FF-Control Point Insertion technique (FF-CPI) to achieve the reduction of scan-in patterns by multi-cycle test. The FF-CPI technique modifies the captured values of scan Flip-Flops (FFs) during capture operation by directly reversing the value of partial FFs or loading random vectors. The FF-CPI technique enhances the number of detectable stuck-at faults under the capture patterns. The experimental results of ISCAS89 and ITC99 benchmarks validated the effectiveness of FF-CPI technique in scan-in pattern reduction for POST.

The decentralized energy network is one of the promising solutions as a next-generation power grid. In this system, each house has a photovoltaic (PV) panel as a renewable energy source and a battery which is an essential component to balance between generation and demand. The common objective of the battery management on such systems is to minimize only the purchased energy from a power company, but battery degradation caused by charge/discharge cycles is also a serious problem. This paper proposes a State-of-Health (SOH) aware system-level battery management methodology for the decentralized energy network. The power distribution problem is often solved with mixed integer programming (MIP), and the proposed MIP formulation takes into account the SOH model. In order to minimize the purchased energy and reduce the battery degradation simultaneously, the optimization problem is divided into two stages: 1) the purchased energy minimization, and 2) the battery aging factor reducing, and the trade-off exploration between the purchased energy and the battery degradation is available. Experimental results show that the proposed method achieves the better trade-off and reduces the battery aging cost by 14% over the baseline method while keeping the purchased energy minimum.

This paper analyzes and compares two methods to estimate electromagnetically coupled noises introduced to an antenna due to the nearby circuits at a circuit design stage. One of them is to estimate the power spectrum, and the other one is to estimate the active S11 parameter at the victim antenna, respectively, and both of them use simulated standard S-parameters for the electromagnetic coupling in the circuit. They also need the assumed or measured excitation of noise sources. To confirm the validness of the two methods, an evaluation board consisting of an antenna and noise sources were designed and fabricated in which voltage controlled oscillator (VCO) chips are placed as noise sources. The generated electromagnetic noises are transferred to an antenna via loop-shaped transmission lines, degrading the performance of the antenna. In this paper, detailed analysis procedures are described using the evaluation board, and it is shown that the two methods are equivalent to each other in terms of the induced voltages in the antenna. Finally, a procedure to estimate antenna performance degradation at the design stage is summarized.

The growth of Internet traffic and the variety of traffic classes make network performance extremely difficult to evaluate. Even though most current methods rely on complex or costly hardware, recent research on bandwidth sharing has suggested the possibility of defining evaluation methods that simply require basic statistics on aggregated link utilization, such as mean and variance. This would greatly simplify monitoring systems as these statistics are easily calculable from Simple Network Management Protocol (SNMP) calls. However, existing methods require knowledge of certain fixed information about the network being monitored (e.g. link capacities). This is usually unavailable when the operator's view is limited to its share of leased links or when shared links carry traffic with different priorities. In this paper, departing from the analysis of aggregated link utilization statistics obtainable from SNMP requests, we propose a method that detects traffic degradation based on link utilization samples. It does not require knowledge of the capacity of the aggregated link or any other network parameters, giving network operators the possibility to control network performance in a more reliable and cost-effective way.

Replacement of highly stressed logic gates with internal node control (INC) logics is known to be an effective way to alleviate timing degradation due to NBTI. We propose a path clustering approach to accelerate finding effective replacement gates. Upon the observation that there exist paths that always become timing critical after aging, critical path candidates are clustered to select representative path in each cluster. With efficient data structure to further reduce timing calculation, INC logic optimization has first became tractable in practical time. Through the experiments using a processor, 171x speedup has been demonstrated while retaining almost the same level of mitigation gain.

Image quality assessment (IQA) plays an important role in quality monitoring, evaluation and optimization for image processing systems. However, current quality-aware feature extraction methods for IQA can hardly balance accuracy and complexity. This paper introduces multi-order local description into image quality assessment for feature extraction. The first-order structure derivative and high-order discriminative information are integrated into local pattern representation to serve as the quality-aware features. Then joint distributions of the local pattern representation are modeled by spatially enhanced histogram. Finally, the image quality degradation is estimated by quantifying the divergence between such distributions of the reference image and those of the distorted image. Experimental results demonstrate that the proposed method outperforms other state-of-the-art approaches in consideration of not only accuracy that is consistent with human subjective evaluation, but also robustness and stability across different distortion types and various public databases. It provides a promising choice for image quality assessment development.

The performance of devices based on two dimensional (2D) materials is significantly affected upon prolonged exposure to atmosphere. We analyzed time based environmental degradation of electrical properties of HfS2 field effect transistors. Atmospheric entities like oxygen and moisture adversely affect the device surface and reduction in drain current is observed over period of 48 hours. Two corrective measures, namely, PMMA passivation and vacuum annealing, have been studied to address the diminution of current by contaminants. PMMA passivation prevents the device from environment and reduces the effect of Coulomb scattering. Improvement in current characteristics signifies the importance of dielectric passivation for 2D materials. On the other hand, vacuum annealing is useful in removing contaminants from the affected surface. In order to figure out optimum process conditions, properties have been studied at various annealing temperatures. The improvement in drain current level was observed upon vacuum annealing within optimum range of annealing temperature.

Negative Bias Temperature Instability (NBTI) is one of the serious concerns for long-term circuit performance degradation. NBTI degrades PMOS transistors under negative bias, whereas they recover once negative bias is removed. In this paper, we propose a mitigation method for NBTI-induced performance degradation that exploits the recovery property by shifting random input sequence through scan paths. With this method, we prevent consecutive stress that causes large degradation. Experimental results reveal that random scan-in vectors successfully mitigate NBTI and the path delay degradation is reduced by 71% in a test case when standby mode occupies 10% of total time. We also confirmed that 8-bit LFSR is capable of random number generation for this purpose with low area and power overhead.

The long-term degradation due to aging such as NBTI (Negative Bias Temperature Instability) is a hot issue in the current circuit design using nanometer process technologies, since it causes a delay fault in the field. In order to resolve the problem, we must estimate delay variation caused by long-term degradation in design stage, but over estimation must be avoided so as to make timing design easier. If we can treat such a variation statistically, and if we treat it together with delay variations due to process variability, then we can reduce over margin in timing design. Moreover, such a statistical static timing analyzer treating process variability and long-term degradation together will help us to select an appropriate set of paths for which field testing are conducted to detect delay faults. In this paper, we propose a new delay model with a half triangular distribution, which is introduced for handling a random factor with unknown distribution such as long term degradation. Then, we show an algorithm for finding the statistical maximum, which is one of key operations in statistical static timing analysis. We also show a few experimental results demonstrating the effect of the proposed model and algorithm.

Visual degradation is usually introduced during 3D mesh simplification. The main issue in mesh simplification is to maximize the simplification ratio while minimizing the visual degradation. Therefore, effective and objective evaluation of the visual degradation is essential in order to select the simplification ratio. Some objective geometric and subjective perceptual metrics have been proposed. However, few objective metrics have taken human visual characteristics into consideration. To evaluate the visual degradation introduced by mesh simplification for a 3D triangular object, we integrate the structural degradation with mesh saliency and propose a new objective and multi-scale evaluation metric named Global Perceptual Structural Degradation (GPSD). The proper selection of the simplification ratio under a given distance-to-viewpoint is also discussed in this paper. The accuracy and validity of the proposed metric have been demonstrated through subjective experiments. The experimental results confirm that the GPSD metric shows better 3D model-based multi-scale perceptual evaluation capability.

A new mixed-voltage I/O buffer for low-voltage low-latency operation is proposed in this paper. The proposed buffer adopts a novel delay-based timing-control scheme to efficiently avoid problems like gate-oxide stress and hot-carrier degradation. The proposed timing-control scheme also allows the buffer to have a lower latency for transmitting data by avoiding the use of timing-critical circuits like series-connected transmission gates (TGs) and triple-stacked transistors. The latency for receiving data at low supply voltage is also reduced by employing a variable stacked transistor gate-biasing scheme. Comparison results in an 80-nm CMOS process indicated that the proposed mixed-voltage I/O buffer improved up to 79.3% for receiving the external data and up to 23.8% for transmitting the internal data at a supply voltage of 1.2 V.

We carried out degradation analysis of a blue phosphorescent organic light emitting diode by both impedance spectroscopy and transient electroluminescence (EL) spectroscopy. The number of semicircles observed in the Cole-Cole plot of the modulus became three to two after the device was operated for 567 hours. Considering the effective layer thickness of the initial and degraded devices did not change by degradation and combining the analysis of the Bode-plot of the imaginary part of the modulus, the relaxation times of emission layer and hole-blocking with electron transport layers changed to nearly the same value by the increase of the resistance of emission layer. Decay time of transient EL of the initial device was coincident with that of the degraded one. These phenomena suggest that no phosphorescence quenching sites are generated in the degraded device, but the number of the emission sites decrease by degradation.

In this paper, we discuss software performability evaluation considering the real-time property; this is defined as the attribute that the system can complete the task within the stipulated response time limit. We assume that the software system has two operational states from the viewpoint of the end users: one is operating with the desirable performance level according to specification and the other is with degraded performance level. The dynamic software reliability growth process with performance degradation is described by the extended Markovian software reliability model with imperfect debugging. Assuming that the software system can process the multiple tasks simultaneously and that the arrival process of the tasks follows a nonhomogeneous Poisson process, we analyze the distribution of the number of tasks whose processes can be completed within the processing time limit with the infinite server queueing model. We derive several software performability measures considering the real-time property; these are given as the functions of time and the number of debugging activities. Finally, we illustrate several numerical examples of the measures to investigate the impact of consideration of the performance degradation on the system performability evaluation.

We did an experimental study to investigate the effect of the thermal stress due to the heater for adjusting adaptive flying height (AFH) on the readability and instability of tunneling magnetoresistance (TMR) sensors. The slider head consists of a small heater nearby the read/write elements for controlling the clearance between the read/write elements and the recording medium of the magnetic recording system. It is firstly reported that the thermal stress from the AFH heater induces instabilities and caused head degradation. The thermal stress degrades the reader performance by inducing voltage fluctuations and large noise spikes that causes the magnetic recording system having poor bit error rate (BER). The open loop of the transfer curve indicates that the flipping of a synthetic antiferromagnet (SAF) edge magnetization causes these instabilities. The thermal stress reduces the exchange bias field and the energy barrier to flop the SAF edge magnetization. The dispersion and thermal stability of the antiferromagnetic (AFM) layer are the potential root causes of these SAF instabilities because the larger AFM dispersion in these heads gives less net stabilizing field to SAF layers that lowers the energy barrier to flop the SAF edge magnetization. Scanning electron microscope (SEM) images of these weak heads show rough surface and scratches close to the sensor element. The mechanical stress due to these scratches may additionally impact to the stabilizing field of the SAF.

In this research, the performance degradation of the digital electronic equipment under electromagnetic (EM) disturbance was studied in order to investigate the interference of intra-equipment. To develop the evaluation method of the performance degradation, some communication indexes were measured under EM disturbance. From some experimental results, it is known that the performance degradation of the electronic equipment was estimated by the degradation of "through-put," one of the communication performance indexes. For further investigation of the interference of intra-equipment, the near EM field from a PCB of the electronic equipment and its performance degradation under EM disturbance were measured and compared. From the measured results, the relationship between near field measurement and performance degradation could be obtained in some extent. These facts enable us that the weak area under the EM disturbance application on PCB can be foreseen by measuring the near field emission from the equipment and vise versa.

A two-dimensional (2-D) physical model of n-channel poly-Si LDD TFTs in comparison with that of SD TFTs is presented to analyze hot-carrier degradation. The model is based on 2-D device simulator's Gaussian doping profiles for the source and drain junctions fitted to the lateral and vertical impurity profiles in poly-Si obtained from a 2-D process simulator. We have shown that, in the current saturation bias (Vg

We succeeded in isolating two formaldehyde-degrading fungi, the strains BDF001 and 002, from the rhizospheric soil of formaldehyde-exposed potted golden pothos (Epipremnum aureum), and from the formaldehyde-exposed cultivation soil without plants, respectively. Sequence analysis of the ITS-5.8S rDNA regions confirmed that both fungi were of the same species, Trichoderma virens. These two strains, however, obviously differed from each other in formaldehyde resistance and formaldehyde-degrading ability. The formaldehyde concentration allowing a growth during cultivation for 10 days for the strain BDF001 was up to 0.6%, and that for the strain BDF002 was up to 0.35%. The strain BDF001 showed a formaldehyde-degrading activity 2.3 times higher than that of the strain BDF002. Ranges of the possible growth pH and temperature in the presence of 0.21% formaldehyde were between 4 and 9, and around 25, respectively.