Trench Width Research Articles

Subduction-zone parameters that control slab behavior at the 660-km discontinuity revealed by logistic regression analysis and model selection

The potential mechanisms that drive the behavior of subducted oceanic plates at the 660-km discontinuity are subject to debate. Here we conduct logistic regression analysis and model selection to determine the key subduction-zone parameters in natural subduction zones that discriminate the plate behavior along the discontinuity. We select the key variables based on three information criteria: leave-one-out cross-validation score (LOO), Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC). Among the 17 subduction-zone parameters analyzed, only the trench velocity, convergence rate, and trench width are selected in the simplest model that minimizes BIC. The thermal parameter and several other variables are also selected to minimize AIC and LOO. Our results suggest that a stagnant slab occurs along the 660-km discontinuity when there is a narrow oceanic plate and a retreating trench in natural subduction zones, which has also been modeled in previous numerical simulations. Neither the stress nor the deformation rate of the upper-plate margin is selected in the three optimal models, which suggests that back-arc spreading in natural subduction zones does not globally characterize plate behavior at the 660-km discontinuity, although back-arc spreading and a stagnant slab coincide in some numerical simulations. The combination of subduction-zone data analysis and numerical simulations will therefore provide deep insights into the dynamics of Earth’s deep interior.

Reliability analysis of large-diameter high-grade-steel natural gas pipelines under fault action

There are a lot of researches on qualitative aseismatic measures for buried gas pipeline crossing movable faults. But a few of them are quantitative, especially in the size and shape of the trench. The paper first established the finite element model of the strain of buried pipeline crossing a fault which effected by the size and shape of the trench. And it obtained new soil spring stiffness which considered different buried depth, bottom width of trench, trench slope and elastic modulus of soil. The mechanical analysis model of pipeline is established, and the limit state equation of pipeline is fitted. The reliability and sensitivity of the natural gas pipeline under fault action are analysed by a Monte Carlo method, and the error and accuracy are verified. When the pipeline is under tension, the sensitivity from large to small is buried depth, sand friction angle, pipe diameter, pipeline displacement, trench bottom width, trench depth, clay cohesion, trench slope and clay friction angle; when the pipeline is under pressure, the trench depth and clay cohesion have great influence. The findings of this study provide a reference for pipeline design and safety evaluation under fault action.

Rethinking New York’s “dark shadow”: managing the unclaimed dead on Hart Island, 1869 to the present day

Approximately 11 miles from the bright lights of Manhattan, a barren, windswept island sits in the Long Island Sound. The landscape is punctuated by crumbling buildings, trees snaking through broken windows after decades of neglect. There are no people here, save for the incarcerated men brought over from Rikers Island to dig endless wide trenches, muddy and dark. Under the ground, the remains of over one million of New York’s most unloved citizens lie stacked in mass, unmarked graves. Or so the dominant narrative goes. This 131-acre island is better known as Hart Island, New York’s public cemetery where the unclaimed dead have been buried since the mid-nineteenth century. The site has long been positioned as the city’s ‘dark shadow’, the final resting place of the unwanted, the lonely, the forgotten and the marginalised. Elements of this narrative are undeniably grounded in truth – the stories of those who have ended up here, many of which have been carefully collected by renowned non-profit The Hart Island Project, offer up endless shades of heartbreak, loss and pain. However, the enduring public perception that a city burial here inevitably means a deeply shameful and degrading end to an unfulfilled, unhappy life is not only inaccurate, but it also severely limits the ways in which we can imagine a possible future for this site. This article aims to bring a historical perspective to the complex issues surrounding the public perception of, and possible future uses for, Hart Island, in order to offer an alternative view on how we can better understand sites of death and contemporary approaches to mourning going forward.

Uncertainty quantification of the superposition film cooling with trench using supervised machine learning

Film cooling technology is significant for aero-turbines development. However, uncertainty on operating and manufacturing conditions would put the high-pressure turbines at the risk of unexpected problems. To extend the service life of the gas turbines, it is necessary to conduct an uncertainty analysis of the effects of the geometry parameters at different blowing ratios on film cooling performance. A classical flat-plate film cooling model under the multiple-row superposition conditions with trench is investigated in this study. The uncertainty inputs included the hole location, depth, and width of the trench and compound angle, while the lateral-averaged film cooling effectiveness was seen as the output. To reduce the computational cost, a Multilayer Perceptron (MLP) model based on supervised learning is built to model the nonlinear regression between the film cooling parameters and the film cooling effectiveness. The computational Fluid Dynamics (CFD) method was utilized to provide the training dataset. After rigorous validation and comparison, the MLP model shows higher accuracy and performance than other classical methods. Then the statistical flow and thermal characteristics of the film cooling outputs and variance were analyzed by the Monte Carlo simulation method. Results of sensitivity analysis show that the uncertainty of compound angle has the greatest effect at both low and high blowing ratios, followed by the location of the first row, trench width, and depth. Besides that, the hole pitch upstream gains more influence than those downstream. Also, both at low and high blowing ratios, the uncertain interval due to compound angle is the biggest, and the uncertain interval due to the hole location of the last row is the smallest. In the design and manufacturing process, it is believed that the uncertainty of compound angle, the hole location of the first row, depth and width of the trench should be paid extra attention to.

Combined ultraviolet- and electron-beam lithography with Micro-Resist-Technology GmbH ma-N1400 resist

We present a “mix-and-match” process to create large structures with submicrometer features by combining UV contact lithography and 100 kV electron-beam lithography in a single layer of negative-tone resist: Micro-Resist-Technology ma-N1405. The resist is successfully applied for the fabrication of an on-chip terahertz spectrometer, where the design requires 450 nm wide lines and 300 nm wide trenches in a 150 nm thick niobium-titanium-nitride layer, tolerating errors of ±30 nm. We use a resist thickness of 500 nm, optimized to allow reliable SF6/O2-based reactive ion etching of structures with 30 nm accuracy. We find that resist requires an electron-beam cross-linking dose of 1100 μC/cm2 for an acceleration voltage of 100 kV in combination with a 180 s 100 °C bake on a hot plate and 45 s development. The smallest resist bars made with our dedicated recipe are 100 nm wide, with the smallest gaps about 300 nm. The difference between the designed and realized feature size is between 2 and 30 nm for structures up to 700 nm wide. The optical exposure dose is 300 mJ/cm2 for the same development time and is optimized to produce a positive sloped edge profile allowing good step coverage for subsequent layers. The resist can be applied, shipped, and processed in a time span of a couple of days without notable deterioration of patterning quality.

Molecular Dynamics Study on Behavior of Resist Molecules in UV-Nanoimprint Lithography Filling Process.

In this study, we performed molecular dynamics (MD) simulations of the filling process of few-nanometer-wide trenches with various resist materials in ultraviolet nanoimprint lithography (UV-NIL) to identify the main molecular features necessary for a successful filling process. The 2- and 3-nm wide trenches were successfully filled with the resist materials that had (experimentally determined) viscosities less than 10 mPa·s. The resist composed of a three-armed bulky and highly viscous molecule could not fill the trenches. The radius of gyration of this molecule was smaller than half of the distance in which the first peak of its radial distribution function occurred. The available shapes of 1,6-hexanediol diacrylate (HDDA) and tri(propylene glycol) diacrylate (TPGDA), which are linear photopolymers, were compared to reveal that TPGDA is more flexible and adopts more conformations than HDDA. The terminal functional groups of TPGDA can be close due to its flexibility, which would increase the probability of intramolecular crosslinking of the molecule. This simulation result could explain the difference in hardness between the UV-cured HDDA and TPGDA based materials observed by experiments. The findings revealed by our MD simulations provide useful information for selecting and designing resists for fine patterning by UV-NIL.

Recycling of Excavated Soils from Mini-Trenches Made on Road or Sidewalks to Install Public Utilities

Digging trenches on roads, sidewalks, or banks to accommodate public demands is required for the installation of water pipelines, natural gas lines, electric cables, and optical fibers. The soils extracted from these trenches always have substantial environmental and economic consequences, as these soils are frequently regarded as waste due to their poor engineering properties. As a result, a suitable location and method for disposing these excavated soils must be found, and this procedure is exceedingly costly, time consuming, and environmentally unfriendly. It is far more efficient to reuse these excavated soils for refilling the same trenches. This study is a part of a French national project. The national project aims to dig 5 to 25 cm wide trenches to install public utilities and to refill them using the same excavated material in the form of self-compacting mortar. The goal of this research is to determine the best ecofriendly binder for the soil excavated from various sites by conducting laboratory-scale physio-chemical and mechanical testing. This study examined the unconfined compressive strength (UCS) assessed by both destructive and non-destructive (ultrasonic) testing methods. By utilizing low CO2-emitting ecofriendly binders incorporating industrial byproducts (fly ash and GGBS), this work has broadened the possibility of reusing trench cuttings to refill the same trenches.

Cu Electrochemical Polishing for RDL Process of FOWLP and Effects of Cu Overburden Profiles

Cu electrochemical polishing for planarization in the redistribution layer (RDL) process and the effects of Cu overburden profiles on Cu electrochemical polishing were investigated. Despite the fact that Cu electrochemical polishing is a feasible alternate planarization method, there are issues with obtaining void and bump-free overburden profiles associated with overpolishing for wide trenches. To ensure uniform electrochemical polishing for all width patterns, Cu overburdens were tuned by changing leveler additive concentration, resulting in bumps on the trenches. Uniform Cu overburden polishing was observed at similar overburden areas for all width patterns. The Cu electrochemical polishing results indicated that overburden on trenches and on interlayer dielectrics were important for uniform Cu overburden electrochemical polishing.

Performance of Open and In-Filled (Geofoam) Trenches in Mitigating Ground-Borne Vibrations Induced by Impact Loading

The open or in-filled trenches are often used in engineering practice to mitigate ground vibration induced by different types of vibration sources. A novel approach which is considering the effect of Rayleigh wavelength on the efficiency of open and in-filled trenches coupled with regular specific normalized dimensions was implemented in this study. While impact loading is a very common type of loading (in, e.g., machine foundations, driven pile installation), it was rarely studied in the past. The loading is selected to consist of 12 impact pulses. In this study, it was shown that Rayleigh wavelength controls the effect of trench-normalized dimensions on its performance, and therefore, studying the trench effectiveness based only on its normalized dimensions is a limited assumption. For open trenches, the depth of trench is the key parameter controlling its efficiency, while its width does not have a significant effect except for shallow trenches (normalized width of less than 0.7) in the condition of low Rayleigh wavelength (2.0 m). Also, it was shown that the trench should be installed at a normalized distance of at least 1.0. Furthermore, the numerical results revealed that the effect of the normalized width of the geofoam trench on its efficiency for Rayleigh wavelength {lambda }_{R}=2.0 , mathrm{m} was more than that for {lambda }_{R}=8.0 , mathrm{m}. Also, several graphs for the design of geofoam trenches under different Rayleigh wavelengths were proposed in this study, which could be useful in practice.

Bragg Resonance and Phase Upshift of Linear Water Waves Excited by a Finite Periodic Array of Parabolic Trenches

The Bragg resonant reflection excited by a finite periodic array of parabolic trenches was analytically studied. First, the modified mild-slope equation (MMSE) with implicit coefficients was transformed into an ordinary differential equation with explicit coefficients through variable substitution. Second, an analytical solution to the MMSE was established in terms of the Frobenius series, and the convergence condition for the series solution was given. Finally, by means of the mass-conservation matching conditions, an analytical formula for the reflection coefficient was built. With the analytical formula, the effects of the number, the depth and the width of trenches on the peak value, the phase and the band width of the resonance, were investigated. The results show that, when the depth and width of trenches keep constant, and the number of trenches increases, the Bragg resonance peak value will increase up to 1, while the resonance bandwidth will narrow down and approach a fixed value. When the number and width of trenches keep constant, the Bragg resonance peak value will increase with the depth of trenches. When the number and depth of trenches keep constant, the Bragg resonance peak value will increase at first and then decrease with the width of trenches, which implies that there exists a certain width of trenches to make the Bragg resonance peak value reach the maximum, laying a theoretical base for the optimization of Bragg resonance vs. the trench width. Particularly, the phase upshift of the Bragg resonance wave reflection peak value recently observed over finite periodically arranged cycloidal trenches, was confirmed again over the parabolic trenches. That implies that, the phase upshift of the Bragg resonance reflection peak value is a common phenomenon excited by finite periodic trenches with arbitrary cross sections. Consequently, for sinusoidal ripples and periodic artificial bars, the phase of the Bragg resonance reflection will shift downward, while for an array of periodic trenches, regardless of the shape of the trench cross section, the phase of the Bragg resonance reflection will shift upward. In addition, starting from the initial definition of the Bragg resonance, the mathematical mechanism of the phenomenon of phase upshift is well explained.

Stress Analysis of Tungsten Deposition in a 3D Trench Mold With Regard to Initial Nuclei Shape

Tungsten has been commonly used for fine interconnects due to its good gap-filling characteristics in 3D molds, such as trench patterns. However, tungsten shows high deposition stress. This causes mold distortion because tungsten has low ad-atom mobility, and diffusion-driven relaxation does not occur. To reduce tungsten’s deposition stress, the shape of the nuclei can be controlled, which is an effective way to suppress the mechanical deformation caused by the formation of a grain boundary between free surfaces during the coalescence stage. In this study, elliptical tungsten nuclei with various aspect ratios, which suppress coalescence in the early stage of deposition, were proposed to reduce the deposition stress. Stress was calculated using the finite element method (FEM) in the range of 0.5 to 8 radius ratios of the tungsten nuclei. The bending of the trench mold was calculated due to tungsten stress and additional coalescence between films during the filling process. As a result, the wider the elliptical nucleus was, the lower the film stress, and mold bending between line patterns was also reduced. The defects in the depth and width of the periodic trench influenced the mold bending in the early growth stage and the stage of coalescence between films, respectively.

Sidewall-Implanted Trench Termination for 4H-SiC Devices With High Breakdown Voltage and Low Leakage Current

In this letter, a sidewall-implanted trench termination for SiC devices is proposed and experimentally demonstrated. With the p-type sidewall region implemented by tilted ion implantation, the electric field crowding at the edge of the main junction can be alleviated. Compared with the conventional trench termination, devices with the fabricated sidewall-implanted trench termination exhibits a higher breakdown voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BV</i> ) exceeding 1800V, as well as lower leakage current. Moreover, the minimum trench width for over 1800V blocking is significantly reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14~\mu \text{m}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> . In addition, the sidewall-implanted trench termination shows stronger robustness as the dominant current path is relocated from the trench sidewall to the whole active region.

Design and Dynamic Simulation Analysis of a Wheel–Track Composite Chassis Based on RecurDyn

The traditional chassis has the problems of low trafficability and poor stability under complex and changeable unstructured conditions. Thus, a wheel rail composite chassis is proposed. The chassis had a tracked travel mechanism at the front wheels and a wheeled travel mechanism at the rear wheels. This study presents the design, theoretical analysis and dynamic simulation analysis of the chassis. The maximum values of the passability of the wheel–track composite chassis that can be passed were calculated according to the relevant parameters. Furthermore, the chassis was modeled and simulated using RecurDyn to verify whether the values were reasonable. According to different values of the terrain, slope, vertical obstacle height and trench width, the change regularity of the track tension and driving torque of the chassis were obtained. The chassis is designed to improve the vehicle’s ability to operate under complex and diverse unstructured conditions.

Determination of kinematic and geometric parameters of multi-scraper chain trange excavators on the basis of the semi-blocked critical depth regime of soil cutting

Trench excavators with a chain-scraper working body became widespread in the construction of linearly extended objects. Increasing workloads and rising energy prices call for optimizing the parameters of construction machinery. The most important component of the process of digging the soil with a chain-scraper working body is cutting the soil with scrapers (knives).When calculating the cutting forces, the working body is taken as a complex mechanical system of traction chains and transverse beams, on which in a certain order are arranged and fixed scrapers-knives with known angular parameters. Separation of chips from the soil is carried out by each scraper in the conditions of blocked, semi-blocked and free cutting of the soil. It should also be borne in mind the change in resistivity and energy consumption of soil cutting with a change in chip thickness. The minimum energy consumption of soil destruction takes place at a critical depth of cut. To reduce the energy consumption of the soil destruction process, a method of calculating the parameters of chain-scraper working bodies of trench excavators is proposed, which is based on critical depth cutting of soils. The initial data for the calculation are: technical productivity, m3 / h; maximum trench depth, m; trench width, m; physical and mechanical characteristics of soils (coefficient of adhesion, specific gravity, angles of internal and external friction). The proposed calculation method allows to determine the technological and geometric parameters of the chain-scraper working body with critical depth cutting of soils.

Configurable lossless broadband beam splitters for semi-guided waves in integrated silicon photonics

We show that narrow trenches in a high-contrast silicon-photonics slab can act as lossless power dividers for semi-guided waves. Reflectance and transmittance can be easily configured by selecting the trench width. At sufficiently high angles of incidence, the devices are lossless, apart from material attenuation and scattering due to surface roughness. We numerically simulate a series of devices within the full 0-to-1-range of splitting ratios, for semi-guided plane wave incidence as well as for excitation by focused Gaussian wave bundles. Straightforward cascading of the trenches leads to concepts for 1×M-power dividers and a polarization beam splitter.

Combined analysis methods for investigating titanium and nickel surface contamination after plasma deep etching

Plasma etching techniques can result in damage and contamination of materials, which, if not removed, can interfere with further processing. Therefore, characterisation of the etched surface is necessary to understand the basic mechanisms involved in the etching process and enable process control and cleaning procedures to be developed. A detailed investigation by means of the combined use of scanning electron microscopy coupled with energy‐dispersive X‐ray spectrometry (SEM/EDS), X‐ray photoelectron spectroscopy (XPS) and optical microscopy (OM) has been carried out on deep titanium trenches etched by plasma. This innovative approach has provided a further insight into the microchemical structure of the surface contamination layer on both the titanium and the nickel hard mask surfaces. The described experiments were conducted on 25 to 100‐μm wide trenches, first etched in bulk titanium by an optimised Cl2/SF6/O2‐based inductively coupled plasma process, through an electroplated nickel hard mask. The results allow to identify chlorine, fluorine and carbon as the main contaminating agents of the nickel mask and to associate three oxidation states around the etched trenches highlighting certain specific aspects related to the passivation mechanism. These observations reinforce the scientific relevance of the combined use of complementary optical and imaging analytical techniques.

Novel XPS Technique for Fluorocarbon Layer Evaluation on Nano-Scale Sicoh Sidewalls

Motivation: The Back End of Line (BEoL) in semiconductor industry uses carbon doped silicon oxides (SiCOH), also called ultra-low-k (ULK) or low-k dielectrics as insulating materials. During reactive ion etching (RIE) of those materials, fluorocarbon passivation layer is formed which controls the etch profile and the plasma induced damage of the material. The etch front of the dielectric is dynamically removed during etching. Due to anisotropic plasma the FC layer builds up differently on the trench sidewalls. Therefore the FC layer on trench sidewalls and the trench bottom should be quantified [i]. It is challenging to study the vertical sidewalls in a patterned film. This work aims to implement X-Ray Photoelectron Spectroscopy (XPS) technique to analyze the sidewalls of the etched film and quantify the buildup of passivating FC layer on the sidewalls in different etch recipes. Methodology: Dense SiCOH (k=2.75, open porosity=7%) with initial thickness of 160nm was deposited on 300mm Si wafers. The wafers were patterned using E-beam lithography. The pattern consists of parallel trench arrays of varying trench widths (50nm to 1500nm) and line widths (75nm to 125nm). Wafers were etched with C4F8/CF4/N2/Ar (Recipe_1) and CHF3/CF4 (Recipe_2) plasma in a Dual Frequency Capacitive Coupled Plasma (CCP) etch chamber. Post etch trench depth and critical dimension (CD) bias of the etched structures were measured using spectroscopic ellipsometry and critical dimension scanning electron microscopy (CDSEM) respectively. Each structures were then measured under XPS for the surface chemical composition.The XPS methodology is based on the mathematical separation of the photoelectron signal intensities of the three different surfaces of a trench, namely the Line Top, Trench Sidewalls and Trench Bottom[ii]. In a model-based approach, electron shadowing by the opposite trench sidewall is calculated using the measured geometry from ellipsometry and CDSEM. It assumes that every point surface on the sidewall emits electrons and only the electrons falling in the acceptance cone of XPS electron detector are counted which limits the conical opening to 60º inclined at 50º to sample surface normal (Fig.1a). Analysis depth of the sidewall varies with the trench width and the trench angle. A physical model is developed to calculate the sidewall analysis depth which is not shadowed by the opposite sidewall (Fig.1b).The layout contains various pitch size which constitute different area ratios of Line Top, Trench Sidewalls and Trench Bottom. In order to find the chemical composition of each surfaces independent of their visible areas, the system of linear equations is solved using Multiple Linear Regression method to find out the signal intensity per unit area from all three surfaces, assuming that each surface composition remains constant across every pitch size. Comparison of the signal intensity per unit area indicates amount of sidewall passivation w.r.t trench bottom. As an additional verification to the methodology and electron shadowing, parallel angle resolved XPS (pAR-XPS) have been carried out at the same structure to find out the variation in sidewall contributions with different angles. Observation: Recipe_1 is highly passivating (C4F8 presence) but directional (high Ar content), therefore shows less deposition of FC layer on the sidewalls compared to line top and trench bottom, shown by the least F1s F-C and C1s C-Fx (x=1:3) intensity but high FC layer deposition on flat surfaces with remaining photoresist adding more carbon and nitrogen to line top than trench bottom (Fig.1c).Recipe_2 shows lower passivation (CHF3 presence) and anisotropy (No Ar) than Recipe_1, therefore lower carbon is seen on line top and trench bottom compared to Recipe_1, but a thicker FC layer on sidewalls. In both the recipes sidewalls and trench bottom shows similar level of Si2p Si-O and O1s O-Si signal intensities but only differ in their FC layer buildup due to different plasma chemistry. Line top with higher carbon content has lesser intensity of Si2p Si-O and O1s O-Si than the other with thinner FC layer buildup. Conclusion: The results confirm that the physical model is capable of separating the signal intensities from the three surfaces through which the FC layer on each surfaces have been accurately predicted. Therefore the normal mode XPS technique can be utilized to gain insight into the chemical composition of sidewalls. Acknowledgement: This work was funded via subcontract from Globalfoundries Dresden within the framework Important Project of Common European Interest (IPCEI) by the Federal Ministry for Economics and Energy and by the State of Saxony.

Finite Element Analysis of Wave Barriers Used to Reduce Train Induced Vibrations

The finite element method is used to simulate the soil vibration behavior due to the Basrah-Baghdad passenger train and its effect on a targeted building in the Al-Ma'qal quarter, Basrah governorate. Three-dimensional dynamic elastic analyses are performed to calculate the particle velocities for a train speed of 120 km/hr. The effectiveness of screening using active (10 m long) open trench barriers with variable depth (2 m - 5 m) and width (0.4 m - 0.8 m), is being studied. For a given trench width (0.4 m), the results of the parametric study revealed a considerable effect of trench depth where the screening capability near the trench is increased by (10.4 %, 26.1 %, 36.3 %) due to a (50 %, 100 %, 150 %) increase in depth. The results are less sensitive to the variation in trench width. The screening capability of a double open (0.4 m × 10 m × 2 m) trench system was also investigated, where a mitigation improvement of (36.4 %) was achieved. The vibration mitigation using single and double trench systems, filled with (40 %) rubber content mixture, was also analyzed. It is concluded that using the additional passive trench increases the mitigation of the single system by around 19.1 %. An important finding is that the (40 % rubber + 60 % native cohesive soil) mixture proved to be a good filling material, since the infilled-trench systems produced comparable screening ratios to the open systems, where (97.7 %) and (85.4 %) were accomplished for the single and double systems, respectively.

Graphoepitaxy of Symmetric Six‐Arm Star‐Shaped Poly(methyl methacrylate)‐block‐Polystyrene Copolymer Thin Film

Front Cover: By utilizing directed self-assembly of a lamellar forming six-arm star-shaped poly(methyl methacrylate)-block-polystyrene copolymer [(PMMA-b-PS)6] thin film confined within trenches, Jaeup U. Kim, Jin Kon Kim, and co-workers successfully fabricate two or more different nanopatterns including nanotubes and straight lines on a single substrate by carefully controlling the trench width and the affinity between the blocks and the trench wall. This work can be found in article number 2100411.

THE BEARING CAPACITY OF A CIRCULAR FOOTING ON GYPSEOUS SOIL BEFORE AND AFTER IMPROVEMENT

Bearing capacity of soil is an important factor in designing circular footing. It is directly related to foundation dimensions and consequently its performance. The calculations for obtaining the bearing capacity of a soil needs many varying parameters, for example soil type, depth of foundation, unit weight of soil, etc. In this work, the comparison between the values of bearing capacity of circular footing on gypseous soil before and after improvement determined by two different methods, the first method using compacted cement dust (Case1). The improvement were performed by making trench under the footing filled with compacted cement dust (at its optimum moisture content) at three depths [(Depth of trench, D =Width of trench, B =2 * the radius of footing R); (D=2B=4R) ; (D=3B=6R)], the trench had the same footing Dimensions, The second method is reinforcing gypseous soil with biaxial geogrids (Case2) have been shown to be an effective method for improving the ultimate bearing capacity of granular soils.