Multiple-layer Approach Research Articles

MECHANICS OF SHOALING AT THE HOUSTON SHIP CHANNEL’S BAYPORT FLARE

The Houston Ship Channel (HSC) is one of the most vital and busiest deep-draft navigation channels in the United States. In 2019 in partnership with the Port of Houston, the U.S. Army Corps of Engineers Galveston District (SWG) completed a five-year award-winning mega feasibility study for the HSC Engineering Channel Improvement Project (ECIP). As part of the 2019 HSC ECIP Feasibility Report Environmental Impact Statement (FREIS) and, through ongoing and repeated maintenance events, the Bayport Flare (Flare) was noted as an area of concern due to chronic shoaling that disrupts traffic and requires continuous dredging. The Flare is the intersection of the HSC and Bayport Ship Channel (BSC). This study seeks to (1) improve our understanding of the source and mechanisms for generation of shoaling and (2) develop and assess conceptual alternative countermeasures for shoaling mitigation. To assess and isolate the sources and mechanics of shoaling in the Flare, a multiple layer approach was applied, which included both field and numerical investigations. A workshop was held to develop alternative countermeasures based on the understanding of system dynamics. Alternatives will (1) be optimized based on cost-benefit considerations; (2) have no-adverse impact on navigation nor require revision, to the point practicable, of ongoing ship simulation studies; and (3) may be structural, non-structural or OandM based.

Multiple-Layer Integrated Interleaved Codes: A Class of Hierarchical Locally Recoverable Codes

The traditional definition of Integrated Interleaved (II) codes generally assumes that the component nested codes are either Reed-Solomon (RS) or shortened Reed-Solomon codes. By taking general classes of codes, we present a recursive construction of Extended Integrated Interleaved (EII) codes into multiple layers, a problem that brought attention in literature for II codes. The multiple layer approach allows for a hierarchical scheme where each layer of the code provides for a different locality. In particular, we present the erasure-correcting capability of the new codes and we show that they are ideally suited as Locally Recoverable codes (LRC) due to their hierarchical locality and the small finite field required by the construction. Properties of the multiple layer EII codes, like their minimum distance and dimension, as well as their erasure decoding algorithms, parity-check matrices and performance analysis, are provided and illustrated with examples. Finally, we will observe that the parity-check matrices of high layer EII codes have low density.

A Multiple-Layer Representation Learning Model for Network-Based Attack Detection

Accurate detection of network-based attacks is crucial to prevent security breaches of information systems. The recent application of deep learning approaches for network intrusion detection has shown promising. However, the challenges remain on how to deal with imbalance data and small samples as well as reducing false alarm rate (FAR). To address these issues, this work has proposed a multiple-layer representation learning model for accurate end-to-end network intrusion detection by combining deep convolutional neural networks (CNN) with gcForest. The contributions of this work lie in 1) a new data encoding scheme based on P-Zigzag to encode network traffic data into two-dimensional gray-scale images for representation learning without loss of original information; 2) The combination of gcForest and CNN allows accurate detection on imbalanced data and small scale data with fewer hyperparamters comparing to most existing deep learning models, which increase computational efficiency. The proposed approach is based on a multiple-layer approach consisting of a coarse layer and a fine layer, in which the coarse layer with the improved CNN model (GoogLeNetNP) focuses on identification of N abnormal classes and a normal class. While in the fine layer, an improved model based on gcForest (caXGBoost) further classifies the abnormal classes into N-1 subclasses. This ensures fine-grained detection of various attacks. The proposed framework has been compared with the existing deep learning models using three real datasets (a new dataset NBC, a combination of UNSW-NB15 and CICIDS2017 consisting of 101 classes). The experimental results show that our proposed method outperforms other single deep learning methods (i.e., AlexNet, VGG19, GoogleNet, InceptionV3, ResNet18) in terms of accuracy, detection rate, and FAR, which demonstrates its effectiveness in detecting fine-grained attacks and handling imbalanced datasets with high-precision and low FAR.

Multilayer modeling of the aureole photometry during the Venus transit: comparison between SDO/HMI and VEx/SOIR data

The mesosphere of Venus is a critical range of altitudes in which complex temperature variability has been extensively studied by the space mission Venus Express (Vex) during its eight-years mission (2006-2014). Data collected at different epochs and latitudes show evidence of short and medium timescale variability as well as latitudinal differences. Spatial and temporal variability is also predicted in mesospheric and thermosphere terminator models with lower boundary conditions at 70 km near cloud tops. The Venus transit on June 5-6 2012 was the first to occur with a spacecraft in orbit around Venus. It has been shown that sunlight refraction in the mesosphere of Venus is able to provide useful constraints on mesospheric temperatures at the time of the transit. The European Space Agency's Venus Express provided space-based observations of Venus during the transit. Simultaneously, the Venus aureole photometry was observed using ground-based facilities and solar telescopes orbiting Earth (NASA Solar Dynamic Observatory, JAXA HINODE). As the properties of spatial and temporal variability of the mesosphere are still debated, the opportunity of observing it at all latitudes at the same time, offered by the transit, is rather unique. In this first paper, we establish new methods for analyzing the photometry of the so-called aureole that is produced by refraction of the solar light, and we investigate the choice of physical models that best reproduce the observations. We obtain an independent constraint of 4.8 +/- 0.5 km for the aerosol scale height in the upper haze region above 80 km. We show that a full multiple-layer approach is required to adequately reproduce the aureole photometry, which appears to be sensitive to several second-order variations in the vertical refractivity.

UV-LIGA microfabrication process for sub-terahertz waveguides utilizing multiple layered SU-8 photoresist

A microfabrication process based on UV LIGA (German acronym of lithography, electroplating and molding) is proposed for the fabrication of relatively high aspect ratio sub-terahertz (100–1000 GHz) metal waveguides, to be used as a slow wave structure in sub-THz vacuum electron devices. The high accuracy and tight tolerances required to properly support frequencies in the sub-THz range can be only achieved by a stable process with full parameter control. The proposed process, based on SU-8 photoresist, has been developed to satisfy high planar surface requirements for metal sub-THz waveguides. It will be demonstrated that, for a given thickness, it is more effective to stack a number of layers of SU-8 with lower thickness rather than using a single thick layer obtained at lower spin rate. The multiple layer approach provides the planarity and the surface quality required for electroforming of ground planes or assembly surfaces and for assuring low ohmic losses of waveguides. A systematic procedure is provided to calculate soft and post-bake times to produce high homogeneity SU-8 multiple layer coating as a mold for very high quality metal waveguides. A double corrugated waveguide designed for 0.3 THz operating frequency, to be used in vacuum electronic devices, was fabricated as test structure.The proposed process based on UV LIGA will enable low cost production of high accuracy sub-THz 3D waveguides. This is fundamental for producing a new generation of affordable sub-THz vacuum electron devices, to fill the technological gap that still prevents a wide diffusion of numerous applications based on THz radiation.

Comparison of CERES, WOFOST and SWAP models in simulating soil water content during growing season under different soil conditions

A lysimeter experiment conducted on three soil types in a main agricultural production region of Austria in Marchfeld (latitude 48°12′N, longitude 16°34′E and altitude 150 m above sea level), was used to test the performance of the three widely used crop models, CERES, SWAP and WOFOST. The soils included chernozem, sandy chernozem and fluvisol with a 2.0 m profile depth. Daily measurements of the soil water content were taken using TDR probes (one per 0.3 m of depth) in six replicates for each soil type. The analysis was carried out for winter wheat and spring barley grown on the site during seasons 2000 and 2001 and included a detailed comparison of the simulated and measured soil water contents as well as an analysis of seasonal soil water balances, root front velocities and an evaluation of the modeled crop yields. CERES and SWAP, in contrast to WOFOST, simulated the grain yield of barley and wheat well. All three models simulated soil water content in the profile with similar results. The root mean square error (RMSE) range of soil water content was 0.71–4.67% for barley and 2.32–6.77% for wheat, depending on the model and soil type. None of the models simulated total soil water content in the profile significantly better, but there was a general tendency for the models to overestimate soil water depletion. Both CERES and SWAP mimicked the soil water content dynamics well in the top 0.3 m of the soil. The study shows that the multiple layer approach models (SWAP or CERES) including more sophisticated estimation methods for root growth and soil water extraction should be preferred in comparable environments. Further adjustments of evapotranspiration subroutines to the local conditions should be considered prior to the model use for drought impact assessment, yield forecasting or climate change impact studies.

Automated MALDI-TOF-MS sample preparation in combinatorial polymer research.

A new automated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) sample spotting technique that allows the integration of MALDI sample preparation in the workflow of combinatorial polymer research is described. The technique is performed utilizing a commercially available synthetic robot and was first evaluated with polymer standards of known composition and later on used for the monitoring of the living cationic ring-opening polymerization of 2-ethyl-2-oxazoline. The spotting was carried out as a multiple layer approach, which offers the ability of complex sample preparation without the requirement of premixing the different components. The described technique reduces the time required for sample preparation and offers the possibility of automated sample spotting during polymerization reactions performed in a synthetic robot. This allows the integration of molecular weight screening and polymer end/group determination utilizing MALDI-TOF-MS as a high-throughput tool in combinatorial polymer research.

Evaluation of a new multiple-layer spotting technique for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of synthetic polymers.

A new multiple-layer matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) sample-spotting technique is described. This fast and easy technique was evaluated with poly(ethylene glycol) (PEG) standards and optimized conditions for these synthetic polymers were obtained. PEGs up to 35 kDa were detectable with this approach and single monomer resolution was observed up to 20 kDa. The spotting was performed using a multiple-layer approach, which offers the capability of complex sample preparation without the requirement of premixing the different matrix, analyte and doping salt solutions. The technique reduces the time required for sample preparation and offers high flexibility with respect to sample composition and solvents utilized for the crystallization of the compounds. The technique is thus perfectly suited for applications in combinatorial material research.

Layer reduction technique for composite laminate analysis

In this study, a layer reduction technique to decrease the number of degrees-of-freedom in composite analysis by combining a multiple-layer approach with a single-layer approach is presented. The single-layer approach is of classical laminate theory or high-order shear deformation theory while the multiple-layer approach is the interlaminar shear stress continuity theory. The layer reduction technique increases computational efficiency in composite analysis by reducing an n-layer laminate to a four-layer laminate but retaining the easiness and accuracy in calculating the transverse stresses from constitutive equations directly. The feasibility of this technique is demonstrated by numerical examples of composite laminates under both bidirectional bending and cylindrical bending.

An interlaminar stress continuity theory for laminated composite analysis

A complete analysis of a new lamination theory presented in a previous investigation for studying the interlaminar stresses in both thin and thick composite laminates is developed. This theory is based on a multiple-layer approach. Hermite cubic shape function is used as the interpolation function for composite layer assembly through the thickness direction. Because of the high-order shape function, the theory can satisfy the continuity of both interlaminar shear stress and interlaminar normal stress exactly on the composite interface. It then is able to obtain the interlaminar stresses directly from the constitutive equations. In addition, because of the high-order interpolation function, the transverse shear deformation is considered in the theory. Accordingly, the theory can be used for both thin and thick composite laminates. In this study, the composite laminates under cylindrical bending studied by Pagano are investigated to verify the new theory. Closed form solutions agree excellently with the elasticity results. A finite element technique based on the principle of minimum potential energy is also used for numerical analysis. The numerical results also show excellent agreement with the exact solution.

Simulation of a periodic dielectric corrugation with an equivalent anisotropic layer

A periodic, corrugated, dielectric layer is simulated by an anisotropic dielectric layer of equal thickness. The tensor elements of the equivalent dielectric layer are given in terms of the permittivity of the dielectric material, the period of the surface corrugation, and the width of the corrugations. The validity of this technique is verified by comparing the reflection coefficient of the equivalent layer with that of the corresponding corrugated layer using the moment method. Employing a multiple layer approach, the technique is extended to handle periodic surfaces with arbitrary cross sections which can be used to design millimeter wave dielectric plate polarizers and absorbers.

Dispersion control in magnetostatic wave delay lines

A major impediment to the realization of practical magnetostatic wave (MSW) devices is the inherent non-linear delay versus frequency characteristics of MSW delay lines. Most device applications require either nondispersive (delay vs. frequency slope=0) or linearly dispersive (delay vs. frequency slope = constant) characteristics. There are four basic approaches to the elimination and/or linearization of MSW dispersion: (1) modification of the magnetic film properties as a function of film thickness, (2) modification of the ground plane geometry, (3) modification of the bias field uniformity, and (4) perturbation of the propagation path surface with metal electrode reflective arrays. In principle all four approaches can yield either linearly dispersive or nondispersive characteristics with a suitable choice of bias field orientation and critical design parameters. These dispersion control techniques are reviewed, and data from recent experiments demonstrating the strengths and weaknesses of the various approaches are discussed. To date the most extensive experimental work has been done with the multiple layer (magnetic properties varied as a function of film thickness) and ground-plane spacing techniques. At present the ground-plane spacing technique produces results acceptable for some systems applications, while the multiple-layer approach is still under development.