Cascade Shape Research Articles

Semi-supervised learning for predicting multivariate attributes of process units from small labeled and large unlabeled data sets with application to detect properties of crude feed distillation unit

In a refinery, the accurate estimation of feed properties is crucial for precise real-time optimization (RTO), and thus, developing models for real-time estimation of crude feed properties from plant measurements remains a challenge. The unbalanced dataset arising from varying variable collection frequencies hinders estimation from plant data. To address these challenges, this study initially proposes two novel algorithms, the clustering co-training semi-supervised learning (CCoT-SSL) and stacked co-training semi-supervised learning (SCoT-SSL), to solve the unbalanced dataset problem. In contrast to prior work, this study tackles the estimation of multivariate attributes when available data comprises small labeled and large unlabeled data with a “cascade shape” structure and illustrates the proposed methods by estimating Crude Distillation Units (CDU). Results indicate that CCoT-SSL excels when the base learners are judiciously selected, which is essential for the real-time optimization of CDU and refinery operations.

High Speed Response Organic Photodetectors with Cascade Buffer Layers (Adv. Electron. Mater. 2/2022)

Cascade Shape Profile A high speed response organic photodetector is demonstrated by Kyung-Bae Park and co-workers in article 2100539. The authors apply cascade hole transport layers to the hole-extraction interface, and investigate the introduction of multi-layered hole transport layers with a stepwise energy profile called a cascade shape profile.

High Speed Response Organic Photodetectors with Cascade Buffer Layers

AbstractOrganic photodiodes (OPDs) with improved photo‐response characteristics are reported, which are an important performance indicator. The photo response characteristics of OPDs depend on the decay rate of current due to charge carriers remaining inside the device even after interruption of the irradiated light. In this study, the effect of improving the response speed of OPDs is experimentally investigated by applying a cascade HTL to the hole‐extraction interface and investigated that the introduction of multi‐layered hole transport layers (HTLs) with a stepwise energy profile, called cascade shape profile, is effective in reducing the decay time of the remaining charges. For a two‐layered cascade HTL OPD, the amount of remaining photo‐current is minimized, equivalent to less than 70% that of single‐layered HTL OPDs, when the highest‐occupied‐molecular‐orbital (HOMO) level gaps among anode (indium tin oxide), HTL1, HTL2, and the p‐type semiconductor are close to equal (Φ1 ≈ Φ2 ≈ Φ3). A cascade HTL does not negatively affect the sensitivity of OPDs, suggesting that it provides a promising means of achieving practical organic image sensors.

Novel Shape-Stabilized Phase Change Material with Cascade Character: Synthesis, Performance and Shaping Evaluation

Thermal Energy Storage (TES) materials, such as Phase Change Materials (PCMs) are proven to enhance the energy efficiency in many fields, such as automotive and building sectors, which correspond to the most energy intensive ones. Shape-stabilized PCM and cascade PCM are procedures to overcome the most important barriers when PCMs are applied since PCMs need to be encapsulated for their technical use: the leakage of the liquid phase, corrosion, low heat transfer and narrow temperature of application. In the present study, a novel shape stabilized PCM with cascade performance (cascade shape stabilized phase change material, CSS-PCM) is synthesized via dissolution, which allows up to 60 wt.% of a paraffin-PCM in the final composition. The novel CSS-PCM is based on a biopolymer, the polycaprolactone (PCL), a low melting temperature polyester as polymeric matrix and RT27 and Micronal DS 5040 acting as PCM. To evaluate the performance of the new TES materials developed, several techniques have been used: Differential Scanning Calorimetry (DSC), and Fourier-Transformed Infrared (FT-IR) spectroscopy were used to evaluate the thermophysical properties and the chemical properties of the different formulations. The CSS-PCM show an increment of storage capacity by increasing the PCM content, and the thermal reliability was also tested: some of the CSS-PCM formulations were stable for up to 500 thermal cycles. Finally, as a potential application of the new polymeric-based PCM 3D, a printing attempt was performed in order to analyze the viability of the formulations to be used as 3D printing material as a first proof of concept.

Field ion microscopy of radiation damage on an atomically clean surface of materials

The defects induced by neutrons (E >0.1 MeV) and Ar+ beams (E = 30 KeV) on the atomically pure surface and in the near-surface volume of platinum were studied using field ion microscopy. Experimental results of radiation defect formation in surface layers of materials initiated by neutron bombardment (Pt, E > 0.1 MeV) and ion implantation (in Cu3Au: E = 40 keV, F = 1020 ion/m2, j = 10∼3 A/cm2) are considered. Quantitative estimates of the size, shape, and volume fraction of atomic displacement cascades formed during various types of irradiation in these materials are obtained. It is shown that the average size of radiation clusters after irradiation of platinum with a fast neutron fluence of 6.7« 1022 m−2 (E > 0.1 MeV) is about 3.2 nm. The experimentally established average size of a radiation cluster (disordered zone) in an alloy after ion bombardment is 4 • 4 • 1,5 nm.

Separative Cascade Shape Effect on the Isotopic Mixture Concentration in Cascade Holdup

Numerical studies are performed of the separation of a model multi-component isotopic mixture in a three-stream cascade. The particulars of isotope accumulation as a function of cascade shape (length, stage distribution of interstage flow) are examined. The regularities of the effect of the cascade shape on the component concentration in the cascade holdup are determined. An enriched isotopic mixture can be obtained by accumulation and partial removal of the process gas from the stages where the target component concentration is highest.

Formation of the Dynamic Energy Cascades in Quartic and Quintic Generalized KdV Equations

In this study we investigate for the first time the formation of dynamical energy cascades in higher order KdV-type equations. In the beginning we recall what is known about the dynamic cascades for the classical KdV (quadratic) and mKdV (cubic) equations. Then, we investigate further the mKdV case by considering a richer set of initial perturbations in order to check the validity and persistence of various facts previously established for the narrow-banded perturbations. Afterwards we focus on higher order nonlinearities (quartic and quintic) which are found to be quite different in many respects from the mKdV equation. Throughout this study we consider both the direct and double energy cascades. It was found that the dynamic cascade is always formed, but its formation is not necessarily accompanied by the nonlinear stage of the modulational instability. The direct cascade structure remains invariant regardless of the size of the spectral domain. In contrast, the double cascade shape can depend on the size of the spectral domain, even if the total number of cascading modes remains invariant. The results obtained in this study can be potentially applied to plasmas, free surface and internal wave hydrodynamics.

Self-regulated critical brain dynamics originate from high frequency-band activity in the MEG.

Brain function requires the flexible coordination of billions of neurons across multiple scales. This could be achieved by scale-free, critical dynamics balanced at the edge of order and disorder. Criticality has been demonstrated in several, often reduced neurophysiological model systems. In the intact human brain criticality has yet been only verified for the resting state. A more direct link between the concept of criticality and oscillatory brain physiology, which is strongly related to cognition, is yet missing. In the present study we therefore carried out a frequency-specific analysis of criticality in the MEG, recorded while subjects were in a defined cognitive state through mindfulness meditation. In a two-step approach we assessed whether the macroscopic neural avalanche dynamics is scale-free by evaluating the goodness of a power-law fits of cascade size and duration distributions of MEG deflections in different frequency bands. In a second step we determined the closeness of the power-law exponents to a critical value of -1.5. Power-law fitting was evaluated by permutation testing, fitting of alternative distributions, and cascade shape analysis. Criticality was verified by defined relationships of exponents of cascade size and duration distributions. Behavioral relevance of criticality was tested by correlation of indices of criticality with individual scores of the Mindful Attention Awareness Scale. We found that relevant scale-free near-critical dynamics originated only from broad-band high-frequency (> 100 Hz) MEG activity, which has been associated with action potential firing, and therefore links criticality on the macroscopic level of MEG to critical spike avalanches on a microscopic level. Whereas a scale-free dynamics was found under mindfulness meditation and rest, avalanche dynamics shifted towards a critical point during meditation by reduction of neural noise. Together with our finding that during mindfulness meditation avalanches show differences in topography relative to rest, our results show that self-regulated attention as required during meditation can serve as a control parameter of criticality in scale-free brain dynamics.

Investigation on the effect of holdup and cascade shape in NFSW cascades

No Feed and Single Withdrawal (NFSW) cascades are of non-conventional gas centrifuge cascades. The present study has been conducted to investigate the effect of holdup of pipes and stages as well as the shape of cascade in separating the multi-component isotopes in NFSW cascades. These cascades are optimized by the Particle Swarm Optimization (PSO) algorithm with an advanced objective function to evaluate the effect of the cascade shape. Moreover, we take into account the holdup term in the equations to study the effect of the holdup of pipes and stages. By investigating the effect of the Holdup of pipes and stages, we found that as the holdup increases, the amount of flow concentration changes. We also compare the optimal tapered structure with the square shape of the NFSW cascade. The results showed that the optimal tapered shape is superior over the square shape in separating the middle component of Xenon.

Supersonic Compressor Cascade Shape Optimization under Multiple Inlet Mach Operating Conditions

Transonic compressors are widely used today in propulsion and industrial applications thanks to their higher specific work compared to subsonic. In this work, the aerodynamic optimization of a two-dimensional Computational Fluid Dynamics (CFD) model of the transonic cascade ARL-SL19 is described. The validated computational model is used for a multi-objective optimization of the cascade at three different inlet Mach numbers using a genetic algorithm and an artificial neural network, with the aim of reducing total pressure loss and increasing maximum pressure ratio. Finally, the optimized shapes on the Pareto fronts are investigated, analyzing mechanisms responsible for loss reduction and enhanced compression. Profiles having the lowest losses have flatter camberlines and reduced acceleration of flow on the suction side, while geometries achieving the highest pressure ratio values have a more cambered shape with a concave suction side.

Performance enhancement of industrial high loaded gas compressor using Coanda jet flap

An industrial highly loaded gas compressor with the large turning angles in gas turbines always causes the serious flow separations, which leads to the significant increase in aerodynamic losses and the evident deterioration of the pressure rise ability. In order to solve this issue, a novel active flow control technique inspired by the Coanda effect is introduced in this study. Here, the Zierke & Deutsch airfoil with the camber angle of 65° is selected for the reference profile of the highly loaded compressor cascade. Design of Experiment (DOE) is firstly used to obtain the sensitivity information of the geometric parameters in building the Coanda jet flap. The cascade shape with the optimal aerodynamic performance is then figured out based on the optimization method. The comparison of the flow details between the optimization result and the prototype is performed to further understand the flow mechanisms behind the performance enhancement. Finally, the experimental measurements are conducted to validate the effectiveness of the well-designed Coanda jet flap in the wind tunnel. The numerical and experimental results show that the Coanda jet can effectively improve the aerodynamic performance of the highly loaded cascade. A tradeoff exists between the increased mixing losses near the slot and the decreased shearing effects near the trailing edge when the mass flow rate of the Coanda jet is increased. The total pressure losses can be reduced by up to 18.4% when the normalized mass flow rate of the jet flow is equal to 1%. Meanwhile, the static pressure rise coefficient can be increased by 8.8% when the mass flow rate of the Coanda jet is equal to 1.5%.

Controlling dislocation gliding and propagation in quasi-single crystalline silicon by using -oriented seeds

Dislocations originating from the seed junctions are the most harmful defects in quasi-single crystalline silicon (QSC-Si). In traditional <100>-oriented QSC-Si ingots, dislocations easily develop into cascade shape, or even further form sub-grain boundaries as the ingot grows. In this paper, we have developed a novel <110>-oriented QSC-Si ingot to control the gliding and propagation of dislocations. It is found that the cascade shape is absent and dislocations only aggregate in the {100}/{100} boundary planes of <110>-oriented seeds, revealed by the minority carrier lifetime mapping and photoluminescence image. Accordingly, the internal quantum efficiency of <110>-oriented QSC-Si solar cells is obviously higher than that of the traditional <100>-oriented ones. Nevertheless, it should be noticed that the average photoelectric conversion efficiency of <110>-oriented QSC-Si solar cells could be 0.6% lower than that of traditional ones if the {100}/{100} boundary is included in the solar cell, due to a higher reverse leakage current. This problem can be involved by enlarging the size of seed crystals or adopting better seed arrangement. These results provide a new promising method for the development of high quality QSC-Si in photovoltaic industry.

A method for determining information diffusion cascades on social networks

Information diffusion on social networks has many potential real-world applications such as online marketing, e-government campaigns, and predicting large social events. Modeling information diffusion is therefore a crucial task in order both to understand its diffusion mechanism and to better control it. Our research aims at finding what factors might influence people in adopting a piece of information that is being shared on a social network. In this study, the traditional independent cascade model for information diffusion is extended with discrete time steps. The proposed model is capable of incorporating three different sources of diffusion influence: user-user influence, user-content preference, and external influence. Specifically, these sources of influence are quantified into real values of diffusion probability. To calculate user-user influence, we adopt and extend the disease transmission model according to the role of the user who diffuses the content. User-content preference, which measures the correlation between user preference and the adopted contents, is calculated based on a topic-based model. External influence is detected in a diffusion time step and is quantified and incorporated into our model for the next diffusion time step by applying and solving a logistic function. Moreover, the process of information diffusion is characterized by constructing a tree of information adoption and the diffusion scale is quantified by predicting the number of infected nodes. It is found that these sources of influence, especially external influence, play a significant role in information diffusion and eventually affect the shape and size of the diffusion cascade. The model is validated on both synthetic and real-world datasets. Experimental results confirm the advantage of our proposed method, which significantly improves over the previous models in terms of prediction accuracy

SYNTHESIS OF NEW NITROBENZYLIDENE DERIVATIVES AND PYRROLE-BASED COPOLYMERS FOR DYE-SENSITIZED SOLAR CELLS: EFFECT OF SUBSTITUENT ON OPTO-ELECTRICAL PROPERTIES OF DIP-COATED THIN FILMS

The mastery of the optoelectronic properties of conjugated copolymers by substituting their radicals is a promising way for increasing the light absorption and charge career transport in the organic devices active layer. In this paper, we present the chemical synthesis of four different conjugated benzaldehyde derivatives and pyrrole-based copolymers (P–P:B) followed by their conception in thin films on glass substrates by dip coating root from a solution in dichloromethane. UV–Vis measurements showed absorption in good part of the visible region, with an optical gap around 2 eV. Morphological properties observed by scanning electron microscope of the four P–P:B based thin films illustrated homogenous and continuous surfaces with roughness and surface shape that can be modulated according to Nitrobenzylidene derivative that contains the copolymer. First oxidation ([Formula: see text]) and reduction ([Formula: see text]) potentials of synthetized copolymers have been estimated by cyclic voltammetry which led us to estimate the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), respectively. The HOMO and LUMO energy level diagram of P–P:B compared with the most commonly used organic materials as donor/acceptor couples showed a cascade shape, which allowed us to opt for organic solar cells based on multiple active layers in our aim to improve its performance.

Direct observation of the spatial distribution of primary cascade damage in tungsten

Recently we have presented direct experimental evidence for large defect clusters being formed in primary damage cascades in self-ion irradiated tungsten [Yi et al., EPL 110:36001 (2015)]. This large size is significant, as it implies that strong elastic interaction between the defects will affect their subsequent evolution, especially if defects are formed close together. Here we present a direct experimental observation of the separation between visible defects in self-ion irradiated tungsten, in the form of a 2d pairwise radial distribution function extracted from transmission electron micrographs (TEM). We also present a detailed analysis of the observed radial distribution function, and infer the probable size and shape of individual cascades. We propose and validate a simple exponential form for the spatial distribution of defects within a single cascade. The cascade statistics necessary have been acquired by developing an automated procedure for analysing black-dot damage in TEM micrographs. We confirm that the same model also produces a high-quality fit to the separation between larger defects observed in MD simulations. For the first time we present experimental evidence for the sub-nanometre-scale spatial distribution of defect clusters within individual cascades.

The mass composition of cosmic rays according to data obtained in the SOKOL-2 satellite experiment

The mass number of cosmic-ray nuclei was obtained using the data from the SOKOL-2 satellite experiment. The mean logarithm of the mass number was determined by two independent methods – the direct method using a charge detector and indirect method using cascade shape information obtained by the ionization calorimeter. We obtained the energy dependence of the mean logarithm of the mass number in the energy range 3–200TeV. The analysis of the SOKOL-2 data showed the applicability of the indirect methods to determine the mass number. The values of the mean logarithm of the mass number obtained by different experiments are consistent.

Robust facial landmark tracking via cascade regression

Recently, tremendous improvements have been achieved for facial landmark localization on static images. However, detecting and tracking facial shapes in sequential images is still challenging due to the large appearance variations in unconstrained videos. To address this issue, we present a robust facial landmark tracking system via cascade regression, which is able to deal well with some challenges emerging in the sequential images. Specially, our system employs a pose-based cascade shape regression model to predict the facial landmark locations. Pose-based cascade shape regression model decreases the shape variances in the model learning stage, making the learned regression model more robust to the large pose variances. In addition, we explore a pose tracking model to enhance the temporal consecutiveness between the adjacent frames, and leverage the Kalman filter to make the predicted shape more smooth and stable. Finally, we incorporate a re-initialization mechanism with the facial landmarks as the position priors into the system, which is able to effectively and accurately locate the face when it is misaligned or lost. Experiments on the LFPW, Helen, 300W and 300VW datasets illustrate the superiority of proposed system over the state-of-the-art approaches, and it is worthy emphasizing that our method has won the 300VW competition in the category one.

Atomic structure of cascades of atomic displacements in metals and alloys after different types of radiation

Using the methods of field ion microscopy, we studied radiation induced defects on an atomically clean surface and within a subsurface volume of platinum initiated by the interaction of neutron (E > 0.1MeV) and Ar+ beams (E = 30 keV). It is shown that the interaction of fast neutrons (E > 0.1 MeV) F = 6.7-1021 m-2, F = 3.5-1022 m-2 with matter leads to the formation in the amount of platinum such as radiation damage which occur after ion irradiation by beams of charged Ar+ ions with E = 30 keV, F = 1020 ion/m2. They are observed at a depth of about 1.5-2 nm irradiated under the surface of Pt by ions Ar+. Thus, we have carried out modeling of neutron impact with matter when replacing the neutron beam by an ion beam that causes the same radiation damage in the bulk of the material. Experimental results on atomic-spatial investigation of radiative defect formation in surface layers of materials, initiated by neutron bombardment (of Pt, E > 0.1 MeV) and ion implantation (in Cu3Au: E = 40 keV, F = 1020 ion/m2, j = 10-3 A/cm2), are considered. Quantitative estimates obtained for the size, shape, and volume fraction of cascades of atomic displacements formed under various types of irradiation in the surface layers of the materials. It is showing that the average size of radiation clusters after irradiation of platinum to a fast neutron fluence of 6.7-1022 m-2 (E > 0.1 MeV) is about 3.2 nm. The experimentally established average size of a radiation cluster (disordered zone) in the alloy after ion bombardment is 4×4×1.5 nm.

M3 CSR: Multi-view, multi-scale and multi-component cascade shape regression

Automatic face alignment is a fundamental step in facial image analysis. However, this problem continues to be challenging due to the large variability of expression, illumination, occlusion, pose, and detection drift in the real-world face images. In this paper, we present a multi-view, multi-scale and multi-component cascade shape regression (M3CSR) model for robust face alignment. Firstly, face view is estimated according to the deformable facial parts for learning view specified CSR, which can decrease the shape variance, alleviate the drift of face detection and accelerate shape convergence. Secondly, multi-scale HoG features are used as the shape-index features to incorporate local structure information implicitly, and a multi-scale optimization strategy is adopted to avoid trapping in local optimum. Finally, a component-based shape refinement process is developed to further improve the performance of face alignment. Extensive experiments on the IBUG dataset and the 300-W challenge dataset demonstrate the superiority of the proposed method over the state-of-the-art methods.

Construction and testing of a Top Counting Detector and a Bottom Counting Detector for the Cosmic Ray Energetics And Mass experiment on the International Space Station

The Cosmic Ray Energetics And Mass (CREAM) mission is planned for launch in 2015 to the International Space Station (ISS) to research high-energy cosmic rays. Its aim is to understand the acceleration and propagation mechanism of high-energy cosmic rays by measuring their compositions. The Top Counting Detector and Bottom Counting Detector (T/BCD) were built to discriminate electrons from protons by using the difference in cascade shapes between electromagnetic and hadronic showers. The T/BCD provides a redundant instrument trigger in flight as well as a low-energy calibration trigger for ground testing. Each detector consists of a plastic scintillator and two-dimensional silicon photodiode array with readout electronics. The TCD is located between the carbon target and the calorimeter, and the BCD is located below the calorimeter. In this paper, we present the design, assembly, and performance of the T/BCD.