Significant Quality Degradation Research Articles

PA MBE growth of intermediate-composition InGaN layers for red and near-IR laser sources

This paper presents the results of studying the growth of InGaN layers with a high (50-80%) indium content by molecular beam epitaxy with nitrogen plasma activation on sapphire substrates with GaN/AlN buffer layers. It is shown that the processes of dissociation and phase separation of the growing InGaN layer, which occur in structures with an indium fraction of about 50%, cannot be suppressed due to the transition to a lower temperature growth (470oC->390oC) without significant degradation of the crystalline quality of the formed structures and a sharp decrease in their emissivity. As an alternative approach to suppressing diffusion processes on the growth surface and, as a result, obtaining homogeneous InGaN layers with an [In] content ~50%, high-temperature (470oC) growth under highly nitrogen-enriched conditions (flux ratio III/V ~0.6) was tested. The InGaN layers grown in this way show intense photoluminescence, while at the same time showing no signs of phase separation according to X-ray diffraction data. This is critically important for the possibility of implementing optical amplification and laser generation in such structures in the red region of the spectrum and in the immediately adjacent part of the near infrared region. Keywords: indium and gallium nitride, molecular beam epitaxy, spinodal decomposition, photoluminescence.

Intermediate-Layer Transferable Adversarial Attack With DNN Attention

The widespread deployment of deep learning models in practice necessitates an assessment of their vulnerability, particularly in security-sensitive areas. As a result, transfer-based adversarial attacks have elicited increasing interest in assessing the security of deep learning models. However, adversarial samples usually exhibit poor transferability over different models because of overfitting of the particular architecture and feature representation of a source model. To address this problem, the Intermediate Layer Attack with Attention guidance (IAA) is proposed to alleviate overfitting and enhance the black-box transferability. The IAA works on an intermediate layer <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> of the source model. Guided by the model’s attention to the features of layer <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> , the attack algorithm seeks and undermines the key features that are likely to be adopted by diverse architectures. Significantly, IAA focuses on improving existing white-box attacks without introducing significant visual perceptual quality degradation. Namely, IAA maintains the white-box attack performance of the original algorithm while significantly enhancing its black-box transferability. Extensive experiments on ImageNet classifiers confirmed the effectiveness of our method. The proposed IAA outperformed all state-of-the-art benchmarks in various white-box and black-box settings.

Drone-Base-Station for Next-Generation Internet-of-Things: A Comparison of Swarm Intelligence Approaches

The emergence of next-generation Internet-of-Things (NG-IoT) applications introduces several challenges for the sixth-generation (6G) mobile networks, such as massive connectivity, increased network capacity, and extremely low-latency. To countermeasure the aforementioned challenges, ultra-dense networking has been widely identified as a possible solution. However, the dense deployment of base stations (BSs) is not always possible or cost-efficient. Drone-base-stations (DBSs) can facilitate network expansion and efficiently address the requirements of NG-IoT. In addition, due to their flexibility, they can provide on-demand connectivity in emergency scenarios or address temporary increases in network traffic. Nevertheless, the optimal placement of a DBS is not a straightforward task due to the limited energy reserves and the increased signal quality degradation in air-to-ground links. To this end, swarm intelligence approaches can be attractive solutions for determining the optimal position of the DBS in the three-dimensional (3D) space. In this work, we explore well-known swarm intelligence approaches, namely the Cuckoo Search (CS), Elephant Herd Optimization (EHO), Grey Wolf Optimization (GWO), Monarch Butterfly Optimization (MBO), Salp Swarm Algorithm (SSA), and Particle Swarm Optimization (PSO) and investigate their performance and efficiency in solving the aforementioned problem. In particular, we investigate the performance of three scenarios in the presence of different swarm intelligence approaches. Additionally, we carry out non-parametric statistical tests, namely the Friedman and Wilcoxon tests, in order to compare the different approaches.

Effect of Ni(P) Layer Thickness on Interface Reaction and Reliability of Ultrathin ENEPIG Surface Finish.

Electroless Ni(P)/electroless Pd/immersion Au (ENEPIG) is a common surface finish in electronic packaging, while the Ni(P) layer increases the impedance of solder joints and leads to signal quality degradation in high-frequency circuits. Reducing the thickness of the Ni(P) layer can balance the high impedance and weldability. In this paper, the interfacial reaction process between ultrathin ENEPIG substrates with different Ni layer thicknesses (0.112 and 0.185 μm) and Sn–3.0Ag–0.5Cu (SAC305) solder during reflow and aging was studied. The bonding ability and reliability of solder joints with different surface finishes were evaluated based on solder ball shear test, drop test and temperature cycle test (TCT), and the failure mechanism was analyzed from the perspective of intermetallic compound (IMC) interface growth. The results showed that the Ni–Sn–P layer generated by ultrathin ENEPIG can inhibit the growth of brittle IMC so that the solder joints maintain high shear strength. Ultrathin ENEPIG with a Ni layer thickness of 0.185 μm had no failure cracks under thermal cycling and drop impact, which can meet actual reliability standards. Therefore, ultrathin ENEPIG has broad prospects and important significance in the field of high-frequency chip substrate design and manufacturing.

Effect of Particles of Irregular Size on the Microstructure and Structural Color of Self-Assembled Colloidal Crystals.

Self-assembled colloidal crystals can exhibit structural colors, a phenomenon of intense reflection within a range of wavelengths caused by constructive interference. Such diffraction effects are most intense for highly uniform crystals; however, in practice, colloidal crystals may include particles of irregular size, which can reduce the quality of the crystal. Despite its importance in realizing high-quality structural colors, a quantitative relationship between particles of irregular size, crystal quality, and the resultant structural color response remains unclear. This study systematically and quantitatively investigates the effect of adding particles of irregular size on the microstructural quality and structural color reflectivity of colloidal crystals formed by evaporative self-assembly via experiment and simulation. We examine two sizes of irregular particles─those which are 1.9 times larger and 0.4 times smaller than the host crystal. We find that small irregular particles are more detrimental to surface crystal quality and structural color reflectivity than large irregular particles. When incorporated with 10% volume fraction of irregularly sized particles, the reflectivity of crystal films with large (small) irregularly sized particles decreases by 18.4 ± 5.6% (27.5 ± 5.8%), and a measure of surface crystal quality derived from Fourier analysis of scanning electron microscopy images reduces by 40.0 ± 4.5% (48.8 ± 6.0%). By modeling colloidal films incorporated with irregular particles via molecular dynamics simulation and computing the reflection spectra of the modeled crystals via the finite-difference time-domain method, we find that the peak reflectivity of the assembled structures increases monotonically with overall crystallinity, and that overall crystallinity is correlated with the volume fraction of incorporated irregular particles. The quantitative relationships developed in this study can be applied to predict the level of irregularly sized particles that can be tolerated in colloidal films before significant degradation in crystal quality and reflectivity occurs.

Treating Electrical and Biopotential Artifacts in an EEG Pilot Study Experiment.

With the increase in life expectancy, as well as in the performance and complexity of healthcare systems, the need for fast and accurate information has also grown. EEG devices have become more accessible and necessary in clinical practice. In daily activity, artifacts are ubiquitous in EEG signals. They arise from: environmental, experimental and physiological factors, degrade signal quality and render the affected part of the signal useless. This paper proposes an artifact cleaning pipeline including filters and algorithms to streamline the analysis process. Moreover, to better characterize and discriminate artifacts from useful EEG data, additional physiological signals and video data are used, which are correlated with subject's behavior. We quantify the performance reached by Peak Signal-to-Noise Ratio and clinical visual inspection. The entire research and data collection took place in the laboratories of XPERI Corporation.Clinical Relevance-Since the occurrence of artifacts cannot be controlled, it is essential to have a precise process of recognition, identification and elimination of noise. Therefore, it is important to distinguish EEG artifacts from abnormal activity in order to minimize the chance of EEG misinterpretation, that can lead to false diagnosis, especially regarding the study of epileptiform activities or other neurologic or psychiatric disorders (e.g. degenerative diseases, dementia, depression, sleep disorders, Alzheimer's disease, schizophrenia, etc.).

On-Chip Links With Energy-Quality Tradeoff in Error-Resilient and Machine Learning Applications

This article presents a class of on-chip links that reduce energy at graceful signal quality degradation via low-swing tuning, leveraging the error resilience of prominent applications (e.g., machine learning, vision). To mitigate the exponential quality degradation at low swings, sub-word ranking and non-uniform swing allocation are introduced. An efficient swing selection to exploit local variations is presented. The proposed links also outperform approximate links in terms of energy and its variability at ISO-quality, while allowing full-quality execution when needed. The proposed techniques are demonstrated in a 28-nm testchip with differential and voltage-scaled standard CMOS links. Results on 20 dies and 3200 links under neural network (LeNet-5 and AlexNet) and computer vision workloads show that the energy can be reduced by up to 5.1X on average across 20 dies, compared with a conventionally designed link. When reusing conventional transmitter and receiver for easy integration, the minimum energy is comparable with prior best-in-class links using more advanced CMOS technologies and dedicated circuit techniques.

High pressure processing for raw meat in combination with other treatments: A review

High pressure processing (HPP) is a well-known technology for nonthermal pasteurization of food materials. High pressures above 100 MPa is proven to cause microbial destruction in food. It has been employed in the treatment of meat and meat products in several commercial industries. When considering raw meat preservation, increasing the pressure beyond 400 MPa results in significant quality degradation including color and textural changes. HPP in combination with other technologies help in achieving a reduction in pathogens below 1 log CFU/g of meat. This review analyzes the effect of HPP with salt, mild heat treatment, plant extracts, essential oils, and antimicrobials on the microbial safety of raw meat with a major focus on microbes such as Escherichia coli O157:H7, Listeria monocytogenes, Salmonella, and Lactic Acid Bacteria. Quality changes (texture, color, and lipid oxidation) in the raw meat while achieving the required pathogen reduction using these methods are also discussed. The review helps in understanding how HPP in combination with other hurdle technologies can be used to provide microbiologically safe raw meat for different end-users. Novelty impact statement High pressure processing is a successful nonthermal processing technology that is employed in meat processing industries. Use of combination technologies with HPP had synergistic effect on reducing microbial load in raw meat. Investigation on applying multiple hurdles with HPP in a cost-effective way could help in the successful application of the technology for meat preservation.

An interplay of soil salinization and groundwater degradation threatening coexistence of oasis-desert ecosystems

In salt-affected and groundwater-fed oasis-desert systems, water and salt balance is critically important for stable coexistence of oasis-desert ecosystems, especially in the context of anthropogenic-induced over-development and perturbations due to climate variability that affects the sustainability of human-natural systems. Here, an investigation of the spatio-temporal variability of soil salinity and groundwater dynamics across four different hydrological regions in oasis-desert system is performed. An evaluation of the effects of soil salinization and groundwater degradation interplays on the coexistence of oasis-desert ecosystems in northwestern China is undertaken over 1995–2020, utilizing comprehensive measurements and ecohydrological modelling framework. We note that the process of salt migration and accumulation across different landscapes in oasis-desert system is reshaping, with soil salinization accelerating especially in water-saving agricultural irrigated lands. The continuous decline in groundwater tables, dramatic shifts in groundwater flow patterns and significant degradation of groundwater quality are occurring throughout the watershed. Worse so, a clear temporal-spatial relationship between soil salinization and groundwater degradation appearing to exacerbate the regional water-salt imbalance. Also, the eco-environmental flows are reaching to their limit with watershed closures, although these progressions were largely hidden by regional precipitation and streamflow variability. The oasis-desert ecosystems tend to display bistable dynamics with two preferential configurations of bare and vegetated soils, and soil salinization and groundwater degradation interplays are causing catastrophic shift in the oasis-desert ecosystems. The results highlight the importance of regional adaptive water and salt management to maintain the coexistence of oasis-desert ecosystems in arid areas.

High quality CVD single crystal diamonds grown on nanorods patterned diamond seed

Microwave plasma chemical vapor deposition (MPCVD) has been developed as a popular method to grow artificial single crystal diamonds with high crystal quality due to its feasibility and economical effectivity. However, the surface roughness and defects will lead to the generation of cracks in the growth process and significant degradation of the crystal quality of epitaxial CVD diamond. Although optimized growth parameters and subsequent chemico-mechanical polishing (CMP) could improve the surface morphology of CVD diamond layer for device fabrication, more investigations need to be done. In this study, nano-sized patterns were prepared by self-assembled Ni mask and inductively coupled plasma (ICP) etching method on diamond seed, and the height of nanorods were optimized for high quality single crystal diamond growth. According to the Microscope imaging, Raman spectroscopy, photoluminescence (PL) mapping and X-ray diffraction measurements, the influence of diamond nucleation on nanorod structures has been evaluated. The results demonstrate that the surface morphology and crystal quality of CVD diamond layer can be improved by the nano-sized patterned diamond seed, indicating a promising method for diamond-based device fabrication.

Grain and cooking quality analysis in heat-tolerant QTL introgressed restorer of hybrid rice

Rice grain yield and quality are affected by the high temperature stress to a large extent. Four promising backcross introgression lines (BC2 F8 ) of KMR-3R/N22 carrying qHTSF1.1, qHTSF4.1 and HT Score QTLs were evaluated for high-temperature induced rice grain and cooking quality during Rabi 2021. Late-sown staggered planting was adopted to ensure uniform high-temperature stress on the improved restorers along with the parents used, which resulted in significant yield loss and grain quality degradation due to hightemperature stress. For cooking quality metrics, ANOVA showed significant variation among genotypes (G), treatments (T), and G×T. Among the backcross introgression lines (BILs), RP6338-9 possesses qHTSF4.1 noted to be promising for grain quality traits under high temperature stress.

Local synergies and antagonisms between meteorological factors and air pollution: A 15-year comprehensive study in the Sydney region

Associated with rapid urbanization and escalation of bushfire events, Sydney has experienced significant air quality degradation in the XXI century. In this study, we present a 15-year retrospective analysis on the influence of individual meteorological factors on major air pollutants (NO2, O3, PM10 and PM2.5) at 14 different sites in Greater Sydney and Illawarra. By applying a newly developed “zooming in” approach to long-term ground-based data, we disclose general, seasonal, daily and hourly patterns while increasing the level of spatial associativity. We provide evidence on the pivotal role played by urbanization, sprawling dynamics, global warming and bushfires on local meteorology and air pollution. We strike associations between temperature and O3, both as average trends and extremes, on account of increasing heat island effects. The role of wind in a coastal-basin environment, influenced by a vast desert biome inland, is investigated. A steady trend towards stagnation is outlined, boosted by enhanced urban roughness and intensified heat island circulation. Relative humidity is also crucial in the modulation between NO2 and O3. With a sharp tendency towards drier and hotter microclimates, NO2 levels dropped by approximately 50% over the years at all locations, while O3's median levels almost doubled in the last 10 years. Further, O3 and PMs shifted towards more frequent extreme events, strongly associated with the exacerbation of bushfire events. Such results suggest an urgent need to prioritize emission control, building air tightness improvement and urban heat mitigation, towards a future-proof governance in Sydney and similar regions in the world.

Clinical and Radiological Safety of Retained Implantable Doppler Devices Used for Free Flap Monitoring.

Implantable Doppler devices are reliable adjuncts used for free flap monitoring. Occasionally, the probe/wire is not removed and remains in the soft tissues. The clinical safety of the retained probes and safety and compatibility with magnetic resonance imaging (MRI) have not been studied. We present a series of retained implantable Doppler probes examining clinic outcomes, safety and compatibility with MRI, and effect on MRI image quality. A retrospective review was conducted of patients who had an implantable Doppler device for free flap monitoring between July 2007 and August 2018. Routine post-operative imaging was reviewed for all patients to identify incidental findings of a retained probe. A subset of patients with retained implantable Doppler probes who underwent MRI was identified. Magnetic resonance images were reviewed to detect any degradation of image quality. A total of 323 patients who had an implantable Doppler device placed were reviewed 18 (5.6%) patients were identified with a retained probe and were included in this study. Mean age was 49 years with mean follow-up of 34.4 months. One potential device-related complication occurred in 1 (5.6%) patient. A total of 32 MRI scans were performed in 8 patients with retained devices, including 6 patients who underwent a total of 21 MRIs of the surgical site. There were no complications related to the MRI scans, and we found no significant degradation of image quality. Retained implantable Doppler probes were not associated with substantial adverse clinical outcomes nor affected MRI image quality of the surgical site.

Effect of X-ray free-electron laser-induced shockwaves on haemoglobin microcrystals delivered in a liquid jet

X-ray free-electron lasers (XFELs) enable obtaining novel insights in structural biology. The recently available MHz repetition rate XFELs allow full data sets to be collected in shorter time and can also decrease sample consumption. However, the microsecond spacing of MHz XFEL pulses raises new challenges, including possible sample damage induced by shock waves that are launched by preceding pulses in the sample-carrying jet. We explored this matter with an X-ray-pump/X-ray-probe experiment employing haemoglobin microcrystals transported via a liquid jet into the XFEL beam. Diffraction data were collected using a shock-wave-free single-pulse scheme as well as the dual-pulse pump-probe scheme. The latter, relative to the former, reveals significant degradation of crystal hit rate, diffraction resolution and data quality. Crystal structures extracted from the two data sets also differ. Since our pump-probe attributes were chosen to emulate EuXFEL operation at its 4.5 MHz maximum pulse rate, this prompts concern about such data collection.

Stock market signals and consequences of securities class actions lawsuits: a microstructure perspective

We perform a microstructure analysis of trading activities pre- and post-class period end-dates of securities class action lawsuits. We posit that these events are likely to significantly impact the spreads of affected firms, in addition to the well documented market capitalization loss that spurs the legal action. We detect neither meaningful widening of spreads nor change in put-call ratios ahead of the class period end-date, suggesting no microstructure or option open interest signal of the upcoming event. However, we present strong evidence of a significant degradation in market quality post the class period end-date based on widening spreads lasting for at least 60 trading days. We also document a trading volume spike and share price decline around the event date. Our research shows the impact on shareholders extends beyond the capitalization loss through wider spreads for defendant firms, while the same is not true for a control sample.

Modified Stiffness-Based Soft Optical Waveguide Integrated Pneumatic Artificial Muscle (PAM) Actuators for Contraction and Force Sensing

This article presents design, fabrication, characterization, and experimental verification of a new sensing method (soft optical sensing) for pneumatic artificial muscle (PAM) actuators. Soft optical waveguides are designed and fabricated using the proposed modified stiffness concept for soft sensors. The design of the sensor allows us to measure both contraction and force of a PAM actuator under loaded conditions. This proposed method makes it possible to have a highly sensitive actuator system with linear contraction sensing. The sensorized PAMs are supposed to work in high-pressure applications with the ability to be used repeatedly without significant degradation in signal quality. To characterize and validate the proposed method, two PAM actuators make use of two separately designed test systems to plot and model the characteristic curves. Finally, the validation for control is provided using measured sensor data as feedback to the controller.

New Insights into Image Restoration Using Filter Analysis and Noise Models

Image restoration, by eliminating noise and blur from an image, restores the original image. In certain cases, image blur is inevitable, and to eliminate blur caused by camera shake or radar imaging or to remove the effect of image system reaction, etc. There are many suggested methods for noise removal and our paper will investigate and address various models of noise and blur and methods of restoration. There are numerous techniques developed, the most efficient being the Wiener filter and is the fundamental noise reduction approach. Wiener filters may cause some undesired effects in image restoration (significant degradation in quality). Various techniques and models are approached in the establishment of the power spectrum of noise and undegraded images. In terms of noise reduction and image restoration, this paper studies the Wiener filter's assumption and quantitative performance improvement. The SNR is improved considerably. But noise reduction is directly proportional to image degradation. To counter this, we must have prior knowledge of the original image by some PDF (Probability Distribution Function).

How about water? Urban blue infrastructure management in Romania

Decades of economic development and urbanization have led to strong transformations of blue infrastructure, with significant quality degradation and conversions from natural land cover to other human shaped land uses. While critically threatened, blue infrastructure in urban areas is re-emerging as an important solution that contributes to human well-being through provisioning, regulating and cultural ecosystem services. Our study aims to assess the distribution and the availability of urban blue infrastructure in Romanian cities, considered as a first step in understanding the interactions among major urban infrastructures. We found a low availability of the blue infrastructure in Romanian cities, which could have been caused by significant transformations such as improvements against flooding and conversions to built-up land. Furthermore, we identify associations between cities' share of blue infrastructure and their socio-economic and geographic characteristics. We found that the surface of blue infrastructure is shaped by both morphological features and historical legacies. Our study therefore suggests how such results could be used to enhance the multi-functionality of blue infrastructure to provide social-ecological and economic benefits in densely urbanised areas.

PERFORMANCE EVALUATION OF RADIO OVER FIBER SYSTEM BY EMPLOYING OPTICAL AMPLIFIERS EDFA AND SOA

As per the centralized operations in a radio over fiber (RoF) system, the transmission distance can be increased between the control station and base station. The transferring of the optical signal over large distances results in transmission loss, such as attenuation, fiber tap, fiber splice, etc., which cannot be ignored after a 5 km optical fiber distance, because the transmission losses result in the degradation of signal quality at the receiver end. This creates the need for optical amplifiers to amplify the light signal. The optical amplifiers further enhance the transfer speeds and quantity of transferred data. This paper analyzes the performance of a RoF system by employing optical amplifiers, such as an erbium doped fiber amplifier (EDFA) and a semiconductor optical amplifier (SOA) over different fiber distance. The outcomes and features of an EDFA- and a SOA-based RoF system are also discussed. Finally, the comparative analysis is found by proposed model simulation in OptSIM software. The rapid increment in the undesired nonlinear terms are found over a fiber distance from 5 to 10 km by EDFA- and SOA-based RoF systems, and the obtained results play an important role for maintaining signal quality over fiber transmission distance.

Target Adaptive Differential Iterative Reconstruction (TADI): A Robust Algorithm for Real-Time Electrical Impedance Tomography

Electrical impedance tomography (EIT) is a noninvasive functional diagnostic technique that has been successfully applied to human lung and brain. EIT reconstruction is an ill-conditioned problem: the regularization parameters establish a trade-off between acceptable data fitting and acceptable solution stability. This trade-off is necessary to select the optimal regularization parameters for each data frame to continuously obtain high-quality images in real-time monitoring. However, using the objective regularization parameter selection method before each image reconstruction may reduce the reconstruction efficiency, and using heuristic selection for all images may cause significant quality degradation, thereby creating challenges in long-term clinical EIT monitoring. This study explores a robust EIT target adaptive differential iterative reconstruction algorithm that does not require the advance selection of the optimal regularization parameter to facilitate the clinical application of EIT long-term bedside monitoring. Specifically, second-order Taylor approximation expansion and Euler–Lagrange theorem were used to derive the conductivity differential iteration relationship. Furthermore, the reconstruction quality and generalization ability of the proposed algorithm were validated based on comparisons with the L-curve and the generalized cross-validation parameter selection methods through simulations, phantom experiments, and human lung recruitment data. Compared with the L-curve and generalized cross-validation methods, the TADI algorithm reduces the position error by 33.07% and 47.17%, the ringing by 26.49% and 32.69%, and the shape deformation by 18.34% and 19.40% on average, respectively. The results revealed that the TADI algorithm could achieve a significant improvement over the existing state-of-the-art methods in terms of stability, consistency, and efficiency.