Non-uniform Depths Research Articles

SparseDC: Depth completion from sparse and non-uniform inputs

We propose SparseDC, a model for Depth Completion from Sparse and non-uniform inputs. Unlike previous methods focusing on completing fixed distributions on benchmark datasets (e.g., NYU with 500 points, KITTI with 64 lines), SparseDC is specifically designed to handle depth maps with poor quality in real usage. Our SparseDC makes two major contributions. First, we design a simple strategy, called SFFM, to improve the robustness under sparse inputs by explicitly filling the unstable depth features with stable image features. Second, we suggest utilizing a two-branch feature embedder in order to forecast the exact local geometry of regions with available depth values and accurate structures in regions with no depth. The key of the embedder is an uncertainty-based feature fusion module called UFFM to balance the local and long-term information extracted by CNNs and ViTs. Numerous experiments conducted both indoors and outdoors show how robust and effective our framework is when facing sparse and non-uniform input depths. And SparseDC outperforms the current state-of-the-art (SOTA) method, CFormer, with varying inputs. We use less parameters (38.2M < 45M) and achieve a +18.6% increase in the REL metric and a +9.9% increase in the RMSE metric on NYU Depth dataset. The pre-trained model and the complete code repository can be accessed at https://github.com/WHU-USI3DV/SparseDC.

A fully coupled Hydraulic Mechanical Chemical approach applied to cementitious material damage due to carbonation

Coupled Thermal-Hydraulic-Mechanical-Chemical (THMC) approaches may be important for assessing the long-term durability of cementitious materials. We present a multiphysics approach to overcome past limitations of THMC modelling and validate it based on experimental results of accelerated carbonation tests. Our numerical approach rests on a sequential coupling between Hytec and Cast3m. Hytec computes the evolution of hydraulic and mineralogical fields allowing to compute the micromechanical properties (e.g. Young’s modulus). The mineral reactions generate tensile stresses and Cast3M computes the associated strain tensors and the damage evolution represented by the opening or sealing of cracks, impacting subsequent reactive transport processes. Our approach manages to qualitatively represent the crack patterns and non-uniform degradation depths observed on microtomographic images of carbonated cement samples, which can only be explained by the coupled dynamics of chemical and mechanical processes. Our approach can be extended to a wide range of cement-concrete pathologies and contexts.

Comparison of the Characteristics of Internal Wave Propagation under Two Surface-Boundary Conditions in Continuously Density-Stratified Oceans

Zhang, H.-s.; He, L.; Zhang, Z.-h., and Zhang, Y., 2023. Comparison of the characteristics of internal wave propagation under two surface boundary-conditions in continuously density-stratified oceans. Journal of Coastal Research, 39(2), 303–316. Charlotte (North Carolina), ISSN 0749-0208. Complete theoretical solutions were developed for the propagation of internal waves (IWs) with small amplitudes in a continuously density-stratified ocean under the free surface-boundary condition and rigid lid assumption. Additionally, a numerical model was established for the propagation of IWs under the free surface-boundary condition. In the proposed model, the Euler equations are employed as the governing equations and are discretized with an improved SIMPLE algorithm. In waters with a constant depth, a comparison between the numerical and theoretical results proved the reasonability and accuracy of the proposed method. Additionally, the numerical results under the free surface-boundary condition were compared with those under the rigid lid assumption to analyse the differences between the calculated velocities and density fields. Herein, the influences of characteristic parameters, including the period and amplitude of the incident waves and the coefficient of density and the mode number on the velocity fields under the two surface-boundary conditions, are discussed thoroughly. In the waters with nonuniform varied depths, numerical simulations on the IWs propagation were performed under the two surface-boundary conditions. Differences between the calculated physical fields of IWs in front of and behind the submerged dike are discussed. The detailed analyses showed that differences exist between the calculation results under the two surface-boundary conditions. In particular, they were obvious for the cases with high mode number and variable topography. The results are significant considering the propagation mechanism of IWs under different surface-boundary conditions in a continuously density-stratified ocean.

Experimental investigation into tool wear behaviour of line-array tool electrode during the electrochemical discharge micromilling process

A tool-workpiece gap during the electrochemical discharge machining (ECDM) process is a critical parameter for successfully fabricating microchannels using line-array tool electrodes. Tool wear during the ECDM process increases the tool-workpiece gap and result in non-uniform array microchannel depths or intermittent machining due to reduced heat flux transferred into the workpiece. Hence, proper selection of a tool material that results in uniform tool-tips height/tool-workpiece gap for a longer machining time is essential, especially for the line-array tool electrodes. In this article, the tool wear behaviour of four different materials, i.e., brass, SS304, molybdenum, and tungsten, during fabrication of longer (>15 mm) and deeper (>200 μm) array microchannels using multi-pass ECDM process is reported. The tool wear behaviour at varying machining time/pass numbers was investigated, keeping all other process parameters constant. The experimental results found that the brass electrode's wear rate was relatively faster, and the line-array tool electrode becomes unusable for the ECDM process after 15 min of total machining time. The wear behaviour of molybdenum and tungsten tool materials was similar and resulted in intermittent or no microchannels formation after 35 min of machining time. At the electrolyte-air interface, necking of the tips and subsequent breaking at different machining times was observed for the brass, molybdenum, and tungsten tool materials. Comparatively uniform tips height, microchannel depths, and negligible necking were observed for the SS304 tool electrode after 65 min of machining time. Therefore, SS304 is a suitable tool material for fabricating longer and deeper array microchannels using the multi-pass ECDM process. Moreover, the fabrication of a dual serpentine flow field was demonstrated in the glass workpiece using customized SS304 line-array tool electrodes.

A greedy algorithm for optimal heating in powder-bed-based additive manufacturing

Powder-bed-based additive manufacturing involves melting of a powder bed using a moving laser or electron beam as a heat source. In this paper, we formulate an optimization scheme that aims to control this type of melting. The goal consists of tracking maximum temperatures on lines that run along the beam path. Time-dependent beam parameters (more specifically, beam power, spot size, and speed) act as control functions. The scheme is greedy in the sense that it exploits local properties of the melt pool in order to divide a large optimization problem into several small ones. As illustrated by numerical examples, the scheme can resolve heat conduction issues such as concentrated heat accumulation at turning points and non-uniform melt depths.

Instance-based error correction for short reads of disease-associated genes

BackgroundGenomic reads from sequencing platforms contain random errors. Global correction algorithms have been developed, aiming to rectify all possible errors in the reads using generic genome-wide patterns. However, the non-uniform sequencing depths hinder the global approach to conduct effective error removal. As some genes may get under-corrected or over-corrected by the global approach, we conduct instance-based error correction for short reads of disease-associated genes or pathways. The paramount requirement is to ensure the relevant reads, instead of the whole genome, are error-free to provide significant benefits for single-nucleotide polymorphism (SNP) or variant calling studies on the specific genes.ResultsTo rectify possible errors in the short reads of disease-associated genes, our novel idea is to exploit local sequence features and statistics directly related to these genes. Extensive experiments are conducted in comparison with state-of-the-art methods on both simulated and real datasets of lung cancer associated genes (including single-end and paired-end reads). The results demonstrated the superiority of our method with the best performance on precision, recall and gain rate, as well as on sequence assembly results (e.g., N50, the length of contig and contig quality).ConclusionInstance-based strategy makes it possible to explore fine-grained patterns focusing on specific genes, providing high precision error correction and convincing gene sequence assembly. SNP case studies show that errors occurring at some traditional SNP areas can be accurately corrected, providing high precision and sensitivity for investigations on disease-causing point mutations.

Enhancing energy absorption of circular tubes under oblique loads through introducing grooves of non-uniform depths

Compared with the excellent energy absorption performance under axial loading, thin-walled tubes are vulnerable to instable global bending under oblique loading condition. In this paper, a novel design was developed to improve the energy absorption performance of the thin-walled circular tubes under oblique loading by introducing multiple circumferential grooves with non-uniform depths. Quasi-static experiments and finite element simulations were carried out for tube specimens with different groove configurations. Theoretical models were developed to explain the different energy absorption performance of different tubes. The effects of the loading angle and the friction condition on the energy absorption were also investigated. The results highlight the advantages of the gradiently grooved tubes with groove depth decreasing from loading end to fixed end over the uniformly grooved tubes and the original tubes under the oblique loading condition. The work in this paper can provide a guide for the design of advanced energy absorbing devices for arbitrary loading condition.

Nonlinear Dynamics and Performance Enhancement of Multi-stable Wideband Energy Harvesting: Theoretical Analysis

A new multi-stable wideband harvester is proposed to increase the power density of energy harvesting under wide-bandwidth and low-frequency operations. This harvester can possess with an arbitrary multi-stable state by combining the nonlinearities of stopper-engaged cantilevers and magnetic forces. The harvesting efficiency can be enhanced by interwell oscillations and the global amplitude of the harvester is restricted by the cantilever-stopper engagement. An electromechanical coupling model of the proposed harvester is established to describe its dynamic characteristics. To explore the influence of potential well configurations on a multi-stable energy harvesting, the proposed harvester with four typical potential well configurations is considered while its equivalent nonlinear restoring force can be experimentally identified. The dynamic characteristics of these four configurations at different levels of a harmonic excitation will be explored by both numerical and experimental methods. It is expected that a multiple-well potential with non-uniform depths and shallower outer wells is much more suitable for the proposed system when the external excitation exceeds a critical intensity.

Broadband mid-IR antireflective Reuleaux-triangle-shaped hole array on germanium

A gradient-index Reuleaux-triangle-shaped hole array was fabricated on germanium (Ge) by nanoimprint lithography and inductively coupled plasma processing as a broadband mid-infrared (IR) antireflective surface. The interaction between the {111} planes of cubic crystalline Ge and a circular mold successfully produced an orderly and periodically distributed Reuleaux-triangle-shaped hole array. As a result, the average transmittance increased 15.67% over the waveband at 3–12 μm and remained stable at the incidence angle of up to 60°. The vertices of the Reuleaux triangle showed local enhancement of the electric field intensities due to interference of the incident and reflected radiation fields. It was also found that nonuniform hole depths acted to modulate the transmittance over the 3–12 μm waveband.

Quasi-static drainage in a network of nanoslits of non-uniform depth designed by grayscale laser lithography

A method is reported to fabricate silicon-glass nanofluidic chips with non-uniform channel depths in the range 20-500 nm and micrometer resolution in width. The process is based on grayscale laser lithography to structure photoresist in 2.5 dimensions in a single step, followed by a reactive ion etching to transfer the resist depth profile into silicon. It can be easily integrated in a complete process flow chart. The method is used to fabricate a network of interconnected slits of non-uniform depth, a geometry mimicking a nanoporous medium. The network is then used to perform a pressure step controlled drainage experiment, i.e. the immiscible displacement of a wetting fluid (liquid water) by a non-wetting one (nitrogen). The drainage patterns are analyzed by comparison with simulations based on the invasion percolation algorithm. The results indicate that slow drainage in the considered nanofluidic system well corresponds to the classical capillary fingering regime.

Estimating the microbiological risks associated with inland flood events: Bridging theory and models of pathogen transport

ABSTRACTFlooding is known to facilitate infectious disease transmission, yet quantitative research on microbiological risks associated with floods has been limited. Pathogen fate and transport models provide a framework to examine interactions between landscape characteristics, hydrology, and waterborne disease risks, but have not been widely developed for flood conditions. We critically examine capabilities of current hydrological models to represent unusual flow paths, nonuniform flow depths, and unsteady flow velocities that accompany flooding. We investigate the theoretical linkages between hydrodynamic processes and spatiotemporally variable suspension and deposition of pathogens from soils and sediments; pathogen dispersion in flow; and concentrations of constituents influencing pathogen transport and persistence. Identifying gaps in knowledge and modeling practice, we propose a research agenda to strengthen microbial fate and transport modeling applied to inland floods: (1) development of models incorporating pathogen discharges from flooded sources (e.g., latrines), effects of transported constituents on pathogen persistence, and supply-limited pathogen transport; (2) studies assessing parameter identifiability and comparing model performance under varying degrees of process representation, in a range of settings; (3) development of remotely sensed data sets to support modeling of vulnerable, data-poor regions; and (4) collaboration between modelers and field-based researchers to expand the collection of useful data in situ.

Amplification of Plasma at Different Initial Temperatures inside a Microhole by a Short Laser Pulse and the Effect on the Hole Sidewall

Microholes with diameters varying with the hole depth have promising applications in important applications, but their manufacturing is difficult when the diameter of the hole is very small and/or varies complicatedly with the depth. In the authors’ previous work (Dabir-Moghaddam et al., 2016), physics-based modeling study has been carried out on the interaction of a short laser pulse with a plasma plume that pre-exists in a microhole and the resulted effect on the sidewall of the hole. The model calculations have implied that a novel dual-pulse laser ablation and plasma amplification (LAPA) technique is potentially feasible for drilling microholes with diameters that are different at different hole depths. In this paper, further model calculations have been performed to study the effect of different initial plasma temperatures. Under the studied conditions, it has been found that laser amplification of a plasma plume with a higher initial temperature can lead to a larger heat flux to the hole sidewall surface and a larger surface vaporization depth in the sidewall, which indicates that more significant material removal will be expected. On the other hand, a lower initial plasma temperature can lead to more non-uniform vaporization depths at different sidewall locations, indicating that a spatially more selective material removal will be expected.

An experimental investigation to calculate flow resistance in a steep river

High gradient streams are characterised by steep slopes, coarse bed material with non-uniform size distribution, flash floods and flow depths of magnitude comparable to the bed material size. Another characteristic of high gradient streams is development of armor layers with cobbles and boulders. In these streams, it is often difficult to measure water discharge or flow velocity directly, particularly at high flows; instead, it is necessary to use the indirect methods in which flow velocity and discharge is calculated using a flow resistance predictor. The problem of predicting flow resistance in high gradient alluvial channels with sufficient accuracy is of great interest to hydraulic engineers and is essential for the effective design of water-resources related projects. In this paper, the flow resistance of a steep river with coarse gravel bed material has been investigated by using 75 accurate measured hydraulic data in a relatively wide flume with different coarse gravel bed materials, flow rates and longitudinal slopes. The main purpose of this article reviews the ability of the resistance empirical equations to predict mean flow velocity in gravel river beds. Also, based on measured data, a new equation to predict the flow resistance in steep river has been proposed. This equation along with the other empirical equations has been used to predict the parameters introducing the flow resistance in steep rivers including Manning roughness coefficient, mean flow velocity and Darcy-Weisbach roughness coefficient. The results were compared with measured and calculated hydraulic data and the best equations to predict the Manning’s roughness coefficient in a steep river with coarse gravel bed material are introduced. Finally in order to show the generality and accuracy of the proposed equation, it has been used for the other field data and the results have been discussed.

Feasibility study and optimum loading pattern of a multi-ring inflatable intravaginal applicator

PurposeA cylinder applicator is the standard treatment device for intravaginal brachytherapy. However, they are limited in their ability to simultaneously spare the organs at risk (OAR), and reduce the hot spot in the vaginal mucosa, while achieving adequate dose conformality. This study aims to compare the dosimetric characteristics of single and multi-channel cylinders, and utilizes volume point dose optimizations to investigate the feasibility and optimum loading method for a multi-ring inflatable intravaginal applicator.Material and methodsStudies were designed to: (1) test the feasibility of multi-ring applicators, (2) compare dose distributions between different multi-channel applicators and loading patterns, (3) test non-uniform prescription depths around the multi-ring cylinder.ResultsCompared to a cylinder with a single central channel, a cylinder with 6 lumina arranged around the periphery, providing the lumina had adequate distance to the cylinder surface, could reduce dose beyond the prescription depth. However, when the number of outer lumina increased from 6 to 12, no further dose reduction could be achieved and the high dose volume close to the surface of the cylinder increased. Moreover, an additional ring, with lumina further away from the surface, provided increased dose shaping capabilities, allowing for individualized dose distributions.ConclusionsDose could be reduced to normal tissue and the inner mucosa, and better conformity was seen to unique anatomical shapes. A modified peripheral loading pattern provided the optimum dose distribution, yielding good conformity, dose sparing at adjacent organs, and dose reduction in the high dose region of the vaginal mucosa.

Errata

Two errors occurred in the May issue of Applied Spectroscopy in the Focal Point article “Micro- and Macro-Attenuated Total Reflection Fourier Transform Infrared Spectroscopic Imaging”, by S. G. Kazarian and K. L. A. Chan [ Applied Spectroscopy, vol. 64, issue 5, pp. 135A–152A (2010)]. The first, a reference number error, occurred on page 142A, right column, last sentence in the second paragraph from the bottom. The sentence with the correct reference number, in bold, appears here: “The lack of such alignment in certain commercial accessories would result in non-uniform penetration depths across the imaged area.32” The second error occurred with regard to the caption of Fig. 14 on page 148A. The figure shows an image of PBMA, not PBMS. The correct caption, with the changes in bold, appears here: “Fig. 14. ATR-FT-IR imaging of a thin film of PBMA (poly (butyl methacrylate)) deposited on a diamond ATR measuring surface. The area with the thin film of gold showed some enhancement of the PBMA spectral bands (right hand side of the image).”

A case study of wave height variations due to currents in a tidal entrance

A case study is presented of the effects of tidal currents on the wave heights in a tidal entrance, viz. the Oosterschelde estuary in the Netherlands. Observations of the variation of wave height with tidal elevation during a tidal cycle show a hysteresis. In order to investigate this phenomenon, calculations have been made of wave height changes due to refraction by non-uniform depths and currents, including the occurrence of wave breaking on the shoals in the estuary delta. The calculated wave height variation with tide elevation is found to have a current-induced hysteresis similar to the observed one.

A laboratory analogue model study of ocean-wave induced magnetic fields for cases of non-uniform depths and sea-land interfaces

The laboratory analogue model described by Miles et al. (1977) for the case of a uniform depth ocean is extended to study ocean-wave induced magnetic fields for cases of non-uniform ocean depths and sea-land interfaces. The models studied are: (i) the step and shelf model, (ii) the wedge and shelf model, (iii) the dyke model, (iv) the sea mount model, (v) the sloping bay and shelf model, and (vi) the reef and shelf model. For shallow depths, the behaviour of the induced magnetic field is strongly dependent on the fluid depth over the structure. The shape of the leading edge of the submerged structure, and the contour of the coastline also significantly affect the induced horizontal magnetic field, and possible mechanisms for these effects include wave interference and current channelling. On the basis of the model results, it is apparent that an irregular ocean bottom, or a large submerged structure, should affect the induced magnetic field at the surface only for rather shallow ocean depths of less than 40 m for a fluid wavelength of 360 m.

A laboratory analogue model study of ocean-wave induced magnetic fields for cases of non-uniform depths and sea-land interfaces : Miles, T. and H. W. Dosso, 1979. Phys. Earth planet. Interiors, 19(1):12–20

A laboratory analogue model study of ocean-wave induced magnetic fields for cases of non-uniform depths and sea-land interfaces : Miles, T. and H. W. Dosso, 1979. Phys. Earth planet. Interiors, 19(1):12–20

Induction in the Oceans Explained and Analysed in Terms of Magnetic Merging

Summary Geomagnetic induction in the oceans at high frequencies, corresponding to periods of less than 12 hr, say, for a typical ocean, is explained and analysed in terms of the transport and merging of magnetic field lines. The explanation helps our physical understanding of problems of induction in the oceans by micropulsations. The complete time-varying part of the electromagnetic field, excluding the Earth’s main field, is able to penetrate the conductor at high frequencies by transport of magnetic field lines through the agency of a large electric field near the edge. This electric field also tends to cause a large electric current there when the ocean has no edge slope. Magnetic neutral points in the time-varying part of the field form within the small thickness of the conductor. This enables the magnetic topology to pass through its various changes. The explanation leads to an analysis which applies to oceans of non-uniform depths, and in particular to oceans with an edge slope. A description is given of the way in which the electric current concentrates near the edge of the ocean and the width for this ‘ boundary layer’ is derived. In a previous paper (Hutson, Kendall & Malin 1972, henceforth referred to as HKM) an iterative method, believed to be new in the context of geomagnetism, has been suggested for dealing with the theoretical solution of model induction problems involving wide ranges of frequencies. Here we concentrate upon a physical analysis of the effects to be expected, particularly in the neighbourhood of a coastline. In keeping with HKM we shall try to retain a general approach, in the hope that the results will be found applicable to a wide range of problems with common features. Throughout this paper we exclude the Earth’s main magnetic field from the configuration. As the Earth’s main field varies very slowly with time, its effect on geomagnetic induction problems of the type considered here is negligible. When we refer to neutral points we therefore mean neutral points in the time-varying part of the magnetic field. In the next section we analyse induction phenomena for a particular example in terms of the merging and disappearance of magnetic field lines. In the later sections we shall draw general conclusions and make predictions. Throughout Sections 2-5 we restrict ourselves to the case of an isolated thin conductor with an inducing magnetic field imposed upon it whilst in Section 6, we examine the effects of an underlying superconducting layer. To discuss magnetic merging we shall have to take some account of the finite thickness of the conductor, but we shall otherwise assume that its thickness is negligible.

Two Innovations for Improving Harbor Resonators

The results of an experimental study on two aspects of resonator behavior for harbor entrances are presented. The first aspect involves a battery of three resonators tuned to cover a wide frequency band. It is found that the efficacy of the battery is improved by increasing the distance along the main entrance channel between the individual resonators. An approximate method is presented for estimating the frequency of the most resonant peaks in the response of a battery to a flat incident wave spectrum. The method is a based on previous results. The second aspect investigated is that of nonuniform depths in the resonator configuration. If the still water depth in the resonator is reduced, the length of the resonator for resonance is considerably reduced. This will allow savings in capital expenditure on breakwaters incorporating rectangular resonators, and on excavating the resonators. However, the efficiency of the resonator is also impaired.