Seamless Boundary Research Articles

Two-Dimensional Magnetic Semiconducting Heterostructures of Single-Layer CrI3-CrI2.

Single-layer heterostructures of magnetic materials are unique platforms for studying spin-related phenomena in two dimensions (2D) and have promising applications in spintronics and magnonics. Here, we report the fabrication of 2D magnetic lateral heterostructures consisting of single-layer chromium triiodide (CrI3) and chromium diiodide (CrI2). By carefully adjusting the abundance of iodine based on molecular beam epitaxy, single-layer CrI3-CrI2 heterostructures were grown on Au(111) surfaces with nearly atomic-level seamless boundaries. Two distinct types of interfaces, i.e., zigzag and armchair interfaces, have been identified by means of scanning tunneling microscopy. Our scanning tunneling spectroscopy study combined with density functional theory calculations indicates the existence of spin-polarized ground states below and above the Fermi energy localized at the boundary. Both the armchair and zigzag interfaces exhibit semiconducting nanowire behaviors with different spatial distributions of density of states. Our work presents a novel low-dimensional magnetic system for studying spin-related physics with reduced dimensions and designing advanced spintronic devices.

Numerical models for seamlessly predicting internal diffusion and re-emission of leaked liquid toluene from indoor mortar materials

There have been serious hazardous liquid chemical leakage cases in factories, chemical plants, and laboratories owing to natural disasters or contingent human accidents. Regarding risk management, when high-risk liquid chemical substances are assumed to leak inside enclosed indoor spaces, reasonable prediction of transient and heterogeneous concentration distributions formed around the human body is necessary to develop an appropriate evacuation plan. In particular, understanding the air-phase concentration level in the breathing zone and its duration for inhalation exposure is essential for short-term and high-concentration exposure health risk assessment. Transient and non-uniform concentration distributions can be predicted using computational fluid dynamics (CFD) and in silico human body analysis. However, the development of practical chemical emission models considering internal diffusion and direct evaporative diffusion from floor materials and their seamless boundary conditions must be addressed for practical application. In this study, liquid toluene was assumed to be a representative hazardous chemical substance for risk assessment, and fundamental experiments and corresponding numerical analyses of liquid toluene leaks on mortar materials were conducted. The experimental results suggest that the effective diffusion coefficient of the mortar sample has a significant effect on the sorption timescales of liquid toluene into the materials and significantly changes the air-phase toluene concentrations. The three-dimensional CFD analysis incorporating the practical toluene emission models reproduces the external and internal emission characteristics of leaked toluene on the mortar material and reasonably agrees with the experimental data.

A defiance of language policy: seamless boundaries between languages in Botswana classrooms

Botswana is a multilingual and multicultural country with 25 to 30 languages. In contrast to this everyday lived multilingualism, the country�s language-in-education policy (LIEP) attempts to create a homogenous population in which only two languages are used�Setswana and English. This study investigates language use in classrooms in two schools in Botswana. It explores how the LIEP is enacted in classrooms, which language(s) are used and how. The paper argues that despite a LIEP which tends to prescribe how languages are to be used within education, there is evidence that Botswanan languages are used in much more fluid ways and that the boundaries constructed through the LIEP do not necessarily play out in the day-to-day worlds of teaching and learning in schools. The paper explores the different ways in which the current LIEP meets and diverges from everyday language practices and ends with some suggestions for future policy and practices.

A DLL-Based Quadrature Clock Generator With a 3-Stage Quad Delay Unit Using the Sub-Range Phase Interpolator for Low-Jitter and High-Phase Accuracy DRAM Applications

In an effort to keep pace with bandwidth growth, DRAM employes the quad data rate (QDR) to transfer four data in one clock cycle. In recent graphic memories, QDR is being implemented by a phase-locked loop (PLL). However, it is hard to apply a PLL to main and mobile memories for its high power dissipation and hardware cost. Therefore, we propose a new delay-locked loop-based quadrature clock generator (DLL-QCG) to replace a PLL. A sub-range technique is adopted for a phase interpolator (PI) to achieve a very fine resolution with low power and small area. A tiny resolution mitigates the jitter accumulation effect of the conventional all-digital DLL-QCG and reduces a phase error. With the introduction of the sub-range PI, the delay line structure is changed from two-stage (coarse-fine) to three-stage (coarse-fine-finer). To control this, we also develop a new controller, which ensures clock quality through seamless boundary switching at the fine-to-finer. The circuit is fabricated using a 28 nm CMOS FDSOI technology with a 1 V supply voltage and an area of 0.0072 mm2. It operates from 1.8 to 2.5 GHz and achieves a phase error of 3.35° to 6.35° without a quadrature-phase collector. In addition, the measured RMS and peak-to-peak jitters at operating bandwidth are 1.05 to 1.71 ps and 8.4 to 12 ps, respectively.

Phase engineering of seamless heterophase homojunctions with co-existing 3R and 2H phases in WS2 monolayers.

Self-organized semiconductor-semiconductor heterostructures (3R-2H) that coexist in atomically thin 2D monolayers forming homojunctions are of great importance for next-generation nanoelectronics and optoelectronics applications. Herein, we investigated the defect controlled growth of heterogeneous electronic structure within a single domain of monolayer WS2 to enable in-plane homojunctions consisting of alternate 2H semiconducting and 3R semiconducting phases of WS2. X-ray photoelectron, Raman, and photoluminescence spectroscopy along with fluorescence and Kelvin probe force microscopy imaging confirm the formation of homojunctions, enabling a direct correlation between chemical heterogeneity and electronic heterostructure in the atomically thin WS2 monolayer. Quantitative analysis of phase fractions shows 59% stable 2H phase and 41% metastable 3R phase estimated over WS2 flakes of different sizes. Time-resolved fluorescence lifetime imaging confirms distinct contrast between 2H and 3R phases with two distinct lifetimes of 3.2 ns and 1.1 ns, respectively. Kelvin probe force microscopy imaging revealed an abrupt change in the contact potential difference with a depletion width of ∼2.5 μm, capturing a difference in work function of ∼40 meV across the homojunction. Further, the thermal stability of coexisting phases and their temperature dependent optical behavior show a distinct difference among 2H and 3R phases. The investigated aspects of the controlled in plane growth of coexisting phases with seamless homojunctions, their properties, and their thermal stability will enable the development of nanoscale devices that are free from issues of lattice mismatch and grain boundaries.

Creative and high-quality image composition based on a new criterion

Image compositing techniques are primarily utilized to achieve realistic composite results. Some existing image compositing methods, such as gradient domain and alpha matting, are widely used in the field of computer vision, and can typically achieve realistic results, especially for seamless boundaries. However, when the candidate composite images and the target images have obvious differences, such as color, texture and brightness, the composite results are unrealistic and inconsistent. At the same time, traditional compositing methods focus on basic feature matching, ignoring semantic rationality in composition processing. Quite a few compositing methods thus generate composite results without semantic rationality.In this paper, a new multi-scale image composition method has been presented. In the composition process, wavelet pyramid and basic feature handling were used to achieve multi-scale compositions. More importantly, a new criterion was established, based on the semantic rationality of images, which could ensure that the composite images are semantically valid. A large database was created to facilitate experimentation. The experiments showed that the methodology introduced in this paper produced superior results compared to traditional composition methods; the composite results were not only consistent and seamless, but were also semantically valid.

A Delay Locked Loop With a Feedback Edge Combiner of Duty-Cycle Corrector With a 20%–80% Input Duty Cycle for SDRAMs

A feedback edge combiner is proposed for the duty-cycle corrector (DCC) of a delay locked loop (DLL) to increase the range of allowed input duty cycle. The feedback edge combiner generates the rising edge of a DCC output at the rising edge of an input clock. It generates the falling edge of the DCC output at the rising edge of a feedback clock that is a half-period-delayed signal of the DCC output. A dual-delay-line digitally controlled delay line (DCDL) is used for seamless boundary switching. The chip area of the DCDL is reduced by around 46% by employing the architecture of two short coarse delay lines followed by a fine phase mixer (FPM) and a long coarse delay line in series instead of the architecture of two long coarse delay lines followed by an FPM. The measurements on the chip fabricated in the 65-nm CMOS show the allowed input duty cycle in the range from 20% to 80%; root-mean-square and peak-to-peak jitters of 2.69 and 14.0 ps, respectively, at 2 GHz and 1.2 V; and the operating frequency range from 0.12 to 2.0 GHz at 1.2 V. The measured power consumption is 3.3 mW/GHz at 1.2 V. The chip area is 0.059 mm 2.

Automatic segmentation improvement based on parameter-free spectral matting

In this study, we propose a parameter-free spectral matting technique to automatically achieve essential matting components from the smallest eigenvectors of a Laplacian matrix that accomplish good segmentation results in photography. The proposed scheme is based on discarding alpha components before grouping alpha mattes for high accuracy and better performance in segmentation and compositing. The scheme’s emphasis is on finding the best alpha components of the foreground through opacity estimation in natural photographs without any required user input. The said parameter-free spectral matting technique gives us better performance in terms of seamless boundaries than the existing segmentation techniques. We have compared our scheme with the state-of-the-art interactive segmentation and matting techniques, that is, GrabCut, Graph Cut, and Bayesian Matting, etc. The results of the proposed parameter-free spectral matting scheme are promising and affirm the effectiveness of our method.

Multi-scale image harmonization

Traditional image compositing techniques, such as alpha matting and gradient domain compositing, are used to create composites that have plausible boundaries. But when applied to images taken from different sources or shot under different conditions, these techniques can produce unrealistic results. In this work, we present a framework that explicitly matches the visual appearance of images through a process we call image harmonization , before blending them. At the heart of this framework is a multi-scale technique that allows us to transfer the appearance of one image to another. We show that by carefully manipulating the scales of a pyramid decomposition of an image, we can match contrast, texture, noise, and blur, while avoiding image artifacts. The output composite can then be reconstructed from the modified pyramid coefficients while enforcing both alpha-based and seamless boundary constraints. We show how the proposed framework can be used to produce realistic composites with minimal user interaction in a number of different scenarios.

Seamless Boundaries: Lutfullah's Narrative beyond East and West. Edited by Mushirul Hasan. Annotations and Introduction also by Mushirul Hasan. pp. xxiv. 260. Oxford University Press, Delhi, 2007.

Seamless Boundaries: Lutfullah's Narrative beyond East and West. Edited by Mushirul Hasan. Annotations and Introduction also by Mushirul Hasan. pp. xxiv. 260. Oxford University Press, Delhi, 2007.

Book Review: Seamless Boundaries: Lutfullah's Narrative beyond East and West

Book Review: Seamless Boundaries: Lutfullah's Narrative beyond East and West