Narrow Width Research Articles

Investigating factors of pedestrian safety using ordinal logistic regression in Addis Ababa City roads

Pedestrians are the most victimized group in traffic accidents, and this has raised concerns about pedestrian safety in urban Ethiopia. The aim of this study is to determine the factors that affect pedestrian safety in Addis Ababa city Roads. This study employed a concurrent mixed-methods research method and an explanatory research design. Perception-based pedestrian safety data was collected from respondents’ key informants and personal observation. Exploratory factor analysis was employed to identify significant variables. Besides, the fitness of each variable was evaluated under the assumption of ordinal logistic regression, and the effect size of significant variables was determined using the odds ratio. The result indicates pedestrians are 0.065, 0.181, 0.296, 0.324, 0.289, 0.306, 0.038, and 0.193 times less likely to be safe due to narrow sidewalk width, poor sidewalk and footpath pavement comfort, inclusivity problems of sidewalks and footpaths, illegal vehicle parking, street vending, fast vehicle speed, and absence of traffic signs and lights, respectively. Consequently, the use of ordinal logistic regression offers a practical and effective means of determining pedestrian safety factors. Better pedestrian facilities should be constructed by considering pedestrian flow and diversity. Besides, the concerned body should provide spaces for street vendors and car parking and enforce traffic rules in the appropriate system to control vehicle speed.

Research on structural vertical stiffness evaluation of track-specific suspension bridge under the action of the no-load first train

The track-specific bridge has the characteristics of a large volume of passenger traffic, narrow transverse width, and large excitation. The long-term and high-frequency operating conditions put forward strict requirements for the safety and comfort of the bridge. Aiming at the problem of achieving fast, accurate, and intelligent evaluation of bridges under the coupling action of trains and temperatures, this paper proposes a method for evaluating the structural vertical stiffness of track-specific suspension bridges under the action of the no-load first train. Firstly, the [Formula: see text] (deformation-velocity-time) data of trains on the bridge are analyzed through linkage numerical simulation, track train transponder, and structural safety monitoring system. Secondly, the CART algorithm establishes a regression model for data correction. The mapping relationship between the modified deformation monitoring value and the theoretical calculation value is analyzed to realize the current structural vertical stiffness evaluation. Finally, it is verified by the world’s largest span self-anchored track-specific suspension bridge. The results show that the theoretical deformation value of the most unfavorable deformation section is 268.55 mm, the actual monitoring value is 232.80 mm, the difference is 35.75 mm, and the relative error is 13.3%. The R2 score of the CART regression model is 0.94, and the accuracy of the CART regression model is higher than that of other algorithm regression models. The modified dynamic check coefficient is less than 1, and the ratio of the modified residual deformation value to the maximum deformation value is 7.6%, which meets the specification requirement not exceeding 20%, indicating that the current structural vertical stiffness is in normal operating conditions.

Limit analysis of earthquake-induced landslides considering two strength envelopes

Abstract. Stability analysis of soil slopes undergoing earthquake remains an important research aspect. The earthquake may have some different effects on slope stabilities associated with nonlinear and linear criteria, which need to be further investigated. For homogeneous soil slopes undergoing earthquakes, this paper established the three-dimensional (3D) failure mechanisms with the power-law strength envelope. The quasi-static method was employed to derive the work rate done by the earthquake in limit analysis theory. The critical heights and critical slip surfaces associated with nonlinear and linear criteria were obtained for four slope examples undergoing different seismic loads. Comparisons of the nonlinear and linear results illustrated that two critical inclinations (resulting from the overlap of nonlinear and linear results) both decrease as the seismic force increases, but their difference is almost constant. For steep slopes, the use of linear strength envelope can lead to the non-negligible overestimation of slope critical height. This overestimation will become significant with the increase in seismic force, especially for the steeper slope with a narrow width. Since the seismic force has a positive influence on equivalent internal friction angle, the critical slip surface for the slope-obeying nonlinear envelope tends to be slightly deeper as the earthquake becomes stronger. For steep soil slopes undergoing the earthquake, the development of 3D stability analysis with a nonlinear yield criterion is necessary and significant. These findings can provide some references for the risk assessment and landslide disaster reduction of soil slopes.

Ecological Predictors of Habitat Occupancy for the Southeastern Beach Mouse

Abstract The federally threatened southeastern beach mouse Peromyscus polionotus niveiventris occupies just a fraction of its former range along Florida’s Atlantic coast, mostly within the 72 km of continuous coastline on federal lands of the Cape Canaveral Barrier Island Complex. Although believed to be caused by loss and degradation of habitat associated with human urban expansion, no precise explanation for the reduction in southeastern beach mouse range is known. We used nine years of winter habitat occupancy survey data for a trend analysis, and a subset of four years to identify key factors influencing occupancy dynamics in coastal habitat throughout the core population. Using a maximum likelihood based model selection approach, we tested evidence for the effects of environmental and anthropogenic factors arranged into four hypotheses related to habitat structure, beach erosion, population isolation, and access to inland habitat. As predicted, sites closer to the primary dune, farther from open water, and with higher elevation had higher initial occupancy than sites with the opposite characteristics. Also as predicted, sites farther from open water, with higher elevation, and more coastal strand, less disturbed ruderal vegetation, and in proximity to oak trees had lower site extinction. Contrary to predictions sites closer to infrastructure (roads, railroads, paved sites), and more isolated by narrow width or unsuitable habitat features also had lower extinction, possibly due to restriction of predator access. A Bayesian analysis showed that annual southeastern beach mouse habitat occupancy was generally high (0.63-0.97) but variable across the 72 km of coastal dune spanning most of the remaining species’ range. Simulation showed that the power of the survey was sufficient to detect a 20% decline between years. This study provides a baseline of knowledge about habitat occupancy dynamics for future monitoring and management of the southeastern beach mouse, and other beach mouse sub-species.

Similarity of scaled-down tests of water entry slamming considering the effects of atmospheric pressure and density

The water entry cavity and load characteristics obtained through scaled-down tests are correlated with the atmospheric pressure and density at the free surface. The evaluation of the influence of the cavitation number and atmospheric density coefficient is highly essential for scale tests to improve the prototype prediction accuracy. Focusing on the similarity criterion simulations and load prediction of the scaled-down tests, this study conducts the simulation tests of the water entry characteristics of the scaled-down model under different environments: normal pressure, reduced pressure, and reduced pressure and heavy gas replacement. Moreover, the influence of the cavitation number and atmospheric density coefficient on the multiphase flow, slamming load, and air cushion effect is discussed. The “air cushion effect” is formed at the top of the vehicle during water entry process, which affects the peak narrow pulse width slamming load. Furthermore, the “air cushion” experiences expansion–stability–rupture–escape with increasing water invasion depth. As the atmospheric pressure decreases, the gas tends to thin and the retention inertia weakens. The decrease in the “air cushion” buffering capacity leads to the increase in the slamming load and the expansion of the cavity scale formed by the liquid. Excessive simulation of the dynamic pressure results in the delayed closure of the cavity surface and the slow fall of the water curtain. As the atmospheric density increases, the retention inertia of gas increases because of the increase in the molecular mass, the slamming load gradually decreases, and the closure time of the cavitation and water curtain decreases. The research results of this paper provide some reference for the similarity transformation of the scaled-down test and the pre-research of the prototype.

1.45 ps All-solid-state Q-switched mode-locked laser based on new material Bi2Te3/Sb2Te3

In this work, the improvement of material properties and the optimization of mode-locked devices are discussed. The lateral heterojunction Bi2Te3/Sb2Te3 is prepared by a simple solvothermal method to overcome the limitation of traditional single material and improve the nonlinear optics properties. Based on a Bi2Te3/Sb2Te3 saturable absorber, the stable passive Q-switched mode-locked operation with wavelength of 1064 nm is achieved in Nd: YVO4 crystal. When the pump power reaches 5.5 W, a Q-switched mode-locked output with a maximum power of 910 mW is obtained, and the corresponding optical–optical conversion efficiency is 16.5 %. The repetition frequency of Q-switched pulse envelopes is 83.81 kHz, the pulse width is 1.8 μs, and the pulse energy is 10.8 μJ. The repetition frequency of the mode-locked pulse in the Q-switched envelope is 312.8 MHz and the pulse width is 1.45 ps. This flexible tunable laser provides high peak power, narrow pulse width, and highly stable laser output, broadening its application prospects in high-performance pulsed lasers.

Omnidirectional reflector based on Ta2O5 cylinder-filled IZO mesh structure for flexible and efficient blue TADF top-emission OLEDs

Abstract Flexible top-emission organic light-emitting diodes (f-TEOLEDs) with a high aperture ratio can be used in next-generation wearable electronic applications. However, the advancement of f-TEOLEDs is being hindered by their low light extraction and poor mechanical stability. In this study, we introduce an omnidirectional reflector (ODR) consisting of an Ag/SiO2/Ta2O5 cylinder-embedded indium zinc oxide (IZO) mesh (c-mesh) structure that improves both the light extraction and mechanical flexibility of TEOLEDs using blue thermally activated delayed fluorescence emitters. The proposed ODR achieved a remarkable reflectance of over 96%, particularly in the transverse-electric mode. Furthermore, the Ta2O5 cylinders effectively compensated for the diverse void-induced depths in the IZO mesh, significantly reducing the leakage current between the electrode and the organic layers. In addition, the ODR electrodes exhibited outstanding mechanical stability. Moreover, even after being subjected to 2000 bending cycles over a 5 mm radius, the device luminance changed by less than 20%. Notably, the proposed f-TEOLEDs with Ag/SiO2/c-mesh electrodes demonstrated superior performance, achieving a low turn-on voltage (2.6 V), high current efficiency (33 cd·A−1), and power efficiency of 29.6 lm·W−1. Finally, the devices featured a narrow full width at half maximum of 27 nm under first-order microcavity effects.

Linear power corrections to single top production and decay at the LHC in the narrow width approximation

We consider top quark production and decay in the narrow width approximation and study if the polarisation effects, that manifest themselves in correlations of angular distributions of particles from top quark decays and final state jets in the production sub-process, are affected by linear power corrections. We find that, in general, the answer to this question is affirmative. We also discuss how these non-perturbative corrections affect polarisation observables used to study single top production at the LHC. Finally, we point out that generic kinematic distributions of leptons from top quark decays are affected by linear power corrections, which may have implications for proposals to extract the top quark mass from such leptonic observables. On the other hand, we demonstrate that the distribution of the “out-of-collision-plane” component of the positron momentum is free from linear power corrections, making it an interesting candidate for the top quark mass measurement.

Precursor Reactivity‐Controlled Synthesis of ZnSeTe Spherical Quantum Wells with Narrow and Symmetric Photoluminescence

AbstractEnvironment‐friendly ZnSeTe quantum dots (QDs) are considered as potential blue light emitters. However, due to the large reaction activity difference between Se and Te precursors, ZnSeTe QDs usually can not uniformly alloyed and generate lattice distortion, reducing the color purity or photoluminescence quantum yield (PLQY). A ZnSe/ZnSeTe/ZnSe spherical quantum well (SQW) structure with quasi type‐II energy band arrangement is designed. To promote the uniform growth and even alloying of ternary ZnSeTe, weakly active biphenyltellurium (Ph2Te2) is applied as a new Te source for balancing the reactivity between Te and Se. Epitaxial growth of high crystallinity ZnSeTe with greatly reduced defects is obtained. After ZnS outer layer passivation, the obtained ZnSe/ZnSeTe/ZnSe/ZnS QDs exhibit a high PLQY (≈84%) and a narrow full width at half maxima (19 nm) without asymmetric broaden at 455 nm, contributing to an ultrahigh color purity, which is among the best photoluminescence performance for blue emitting ZnSeTe based QDs. This work provides a new balance strategy of precursor reactivity for synthesizing high color purity and heavy metal free blue ZnSeTe QDs.

Precise Regulation of the Reverse Intersystem Crossing Pathway by Hybridized Long-Short Axis Strategy for High-Performance Multi-Resonance TADF Emitters.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) molecules have experienced great success in organic light-emitting diodes (OLEDs) owing to their outstanding quantum efficiencies and narrow full width at half-maximums (FWHMs). However, the reverse intersystem crossing (RISC) rates of MR-TADF emitters are usually small, which will lead to relatively long triplet exciton lifetime and severe efficiency roll-off. Here, we report an effective molecular design strategy to introduce multichannel RISC pathways and thus increase RISC rates without compromising the color fidelity and emission efficiency by the "hybridized long-short axis (HLSA)" strategy. The TPA-CN-BN shows a near-unity photoluminescence quantum yield, rapid RISC rate of 1.4 × 105 s-1, narrow FWHM of 23 nm, and small singlet-triplet energy gap (ΔEST) of 0.06 eV in solution. The non-sensitized OLED based on TPA-CN-BN exhibits a narrowband emission with the FWHM of 31 nm, in company with external quantum efficiency (EQE) of 37.9%. Notably, the device exhibits the low efficiency roll-off as the EQEs maintain 34.8% and 21.8% at 100 and 1000 cd m-2, respectively, representing the best performance for single-host OLEDs based on the BCzBN skeleton. This study provides a fresh and promising approach to realize high-performance OLEDs with high color purity and remarkable device efficiency.

Precise Regulation of the Reverse Intersystem Crossing Pathway by Hybridized Long‐Short Axis Strategy for High‐Performance Multi‐Resonance TADF Emitters

AbstractMulti‐resonance thermally activated delayed fluorescence (MR‐TADF) molecules have experienced great success in organic light‐emitting diodes (OLEDs) owing to their outstanding quantum efficiencies and narrow full width at half‐maximums (FWHMs). However, the reverse intersystem crossing (RISC) rates of MR‐TADF emitters are usually small, which will lead to relatively long triplet exciton lifetime and severe efficiency roll‐off. Here, we report an effective molecular design strategy to introduce multichannel RISC pathways and thus increase RISC rates without compromising the color fidelity and emission efficiency by the “hybridized long‐short axis (HLSA)” strategy. The TPA‐CN‐BN shows a near‐unity photoluminescence quantum yield, rapid RISC rate of 1.4×105 s−1, narrow FWHM of 23 nm, and small singlet‐triplet energy gap (ΔEST) of 0.06 eV in solution. The non‐sensitized OLED based on TPA‐CN‐BN exhibits a narrowband emission with the FWHM of 31 nm, in company with external quantum efficiency (EQE) of 37.9 %. Notably, the device exhibits the low efficiency roll‐off as the EQEs maintain 34.8 % and 21.8 % at 100 and 1000 cd m−2, respectively, representing the best performance for single‐host OLEDs based on the BCzBN skeleton. This study provides a fresh and promising approach to realize high‐performance OLEDs with high color purity and remarkable device efficiency.

Inkjet printing of mixed layers comprising multinary semiconductor quantum dots and charge transport materials for light‐emitting diode displays

AbstractQuantum dots (QDs) are important luminescent structures with applications in wide‐color‐gamut displays requiring exceptional color reproducibility. Multinary semiconductor QDs are expected to serve as eco‐friendly materials to replace conventional QDs owing to the narrow spectral widths and tunable bandgaps of these QDs. However, the application of multinary QDs, which tend to exhibit defect‐related emissions, to QD light‐emitting diode (QLED) displays will require electroluminescence to be obtained from QLEDs incorporating inkjet‐printed emitting layers. The present work examines QLEDs exhibiting vibrant color emissions based on blue‐emitting Zn–Se–Te QDs, green‐emitting Ag–In–Ga–S QDs, and red‐emitting Ag–Cu–In–Ga–S QDs. Each such QLED contains QD emitting layers comprising a mixture of charge transport materials. The spectra obtained from these RGB QLEDs fabricated by spin‐coating show very high color purity. Passive matrix QLED displays incorporating these QDs are also fabricated by inkjet printing to demonstrate the high color purity that can be obtained from multinary QDs in displays. In conjunction with passive matrix driving, these displays produce clear moving images with vibrant electroluminescence originating from the multinary QDs. The present results indicate that these QDs have significant potential for utilization in wide‐color‐gamut displays.

A Comparative Study on Laser Cutting Performance with Varying Speeds at 10 M Underwater

Despite the dismantling structures that are submerged to significant depths of water during the decommissioning of nuclear power plants, there is limited research on deep-water laser cutting processes. A self-designed pressurized chamber was used in this study and successfully conducted the world’s first laser cutting experiment in a simulated 10 m water depth environment. laser cutting was performed in a 10 m underwater environment, and the cutting efficiency was compared to that observed in a 1 m underwater environment. Therefore, A 100 mm thickness of 304 stainless steel was successfully cut underwater, and the highest cutting speed of 100 mm/min was achieved. The result indicates that, as the cutting speed increased during underwater laser cutting, both the heat input and the mass flow rate of the assist gas decreased, resulting in a narrower rear kerf width and an ineffective evacuation of the molten metal.

Progress on perovskite quantum dots and light-emitting diodes

Abstract. Perovskite quantum dots have become a popular material for the development of new high-efficiency light-emitting diodes (LED) because of their high photoluminescence quantum yield, adjustable luminescence spectrum, narrow spectral width, high defect tolerance and unique quantum limit effect. We review the recent progress based on LED of different types of perovskite quantum dots. First, the properties, existing problems and applications of fully inorganic perovskite quantum dots are introduced. Subsequently, both organic and inorganic perovskites and their applications are discussed, and several methods to improve the LED efficiency of perovskite quantum dots are explored. Finally, this paper analyzes the current challenges of LED of perovskite quantum dots, such as instability and toxicity, and its application prospect in the field of high-efficiency display and lighting is discussed. That is, the EQE of LED based on perovskite quantum dots has increased to more than 20% in four years, and the service life has been extended to tens of hours. This review provides useful insights for the development of more efficient and safer perovskite quantum dot luminescence devices.

Trophic ecology, based on stable isotope values, of long-finned pilot whales Globicephala melas stranded on the Icelandic coast

In Iceland, occurrences of long-finned pilot whales Globicephala melas and strandings in coastal waters are irregular and thought to be related to prey movements; however, little is known about the population’s trophic ecology, making it difficult to assess its role in the regional ecosystem. To investigate the trophic niche of the species, we measured δ13C and δ15N values from skin and muscle samples collected from 16 strandings (12 single and 4 mass strandings) spanning 33 yr (1988-2021). We tested the effects of sex, age class and body length on δ13C and δ15N values within the species. We found that δ13C values did not differ between sexes or age classes, nor did they vary with body length. Values of δ15N did not vary with sex or body length, but varied slightly between adults and juveniles, albeit not sufficiently to support a difference in trophic levels. Whales from different mass stranding events showed similar stable isotope niche widths (approximately 0.20‰2) and overlapping isotope niches (generally >45% of the standard ellipse area corrected for small sample size). Overall, pilot whales in this region showed a narrow isotopic niche width and low intraspecific variation in isotopic niche. Future analyses using complementary chemical tracers and stomach contents will be important to identify the factors driving these patterns. The first measurements of the stable isotope niche of pilot whales presented here provide a baseline for future studies to determine niche overlap between cetaceans in Iceland, contributing to their management and conservation.

Synergistic π-Extension and Peripheral-Locking of B/N-Based Multi-Resonance Framework Enables High-Performance Pure-Green Organic Light-Emitting Diodes.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters offer natural advantages for creating power-efficient, wide-color-gamut OLEDs. However, current green MR-TADF emitters face challenges in simultaneously achieving high color purity and efficient reverse inter-system crossing (RISC), leading to suboptimal device performance. In this study, we propose a synergistic molecular design approach that combines π-extension and peripheral locking to address these challenges. This approach allows for the construction of quadruple borylated MR-TADF emitters that not only deliver precisely tuned pure-green emission with a narrow full width at half maximum (FWHM) of 15 nm, but also exhibit close-to-unity quantum yield, rapid RISC, and optimal horizontal dipole orientation. The resulting sensitizer-free OLED approaches the BT.2020 standard with CIE coordinates of (0.18, 0.74) and demonstrates impressive external quantum efficiency (EQE) of 36.6% at maximum and 31.8% at 1000 cd m-2. Additionally, the device shows good operational stability, with a lifetime (LT80) of 485 hours at an initial luminance of 1000 cd m-2. This study hence offers a promising molecular design strategy that effectively enhances the comprehensive OLED performance.

Synergistic π‐Extension and Peripheral‐Locking of B/N‐Based Multi‐Resonance Framework Enables High‐Performance Pure‐Green Organic Light‐Emitting Diodes

Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters offer natural advantages for creating power‐efficient, wide‐color‐gamut OLEDs. However, current green MR‐TADF emitters face challenges in simultaneously achieving high color purity and efficient reverse inter‐system crossing (RISC), leading to suboptimal device performance. In this study, we propose a synergistic molecular design approach that combines π‐extension and peripheral locking to address these challenges. This approach allows for the construction of quadruple borylated MR‐TADF emitters that not only deliver precisely tuned pure‐green emission with a narrow full width at half maximum (FWHM) of 15 nm, but also exhibit close‐to‐unity quantum yield, rapid RISC, and optimal horizontal dipole orientation. The resulting sensitizer‐free OLED approaches the BT.2020 standard with CIE coordinates of (0.18, 0.74) and demonstrates impressive external quantum efficiency (EQE) of 36.6% at maximum and 31.8% at 1000 cd m‐2. Additionally, the device shows good operational stability, with a lifetime (LT80) of 485 hours at an initial luminance of 1000 cd m‐2. This study hence offers a promising molecular design strategy that effectively enhances the comprehensive OLED performance.

Enhancing the conductivity and crystallinity of (111) platinum films via a two-temperature deposition and substrate annealing

Developing routes to deposit highly conductive (111) oriented platinum films with sub-nanometer roughness will provide a platform to develop unique hexagonal and (111) oriented cubic materials. A two-temperature e-beam deposition process is proposed for the growth of (111) oriented platinum films on Al2O3 to simultaneously induce crystallographic texturing, improve conductivity, and reduce surface roughness. Depositing an initial platinum layer at 700 °C induces texturing then subsequently depositing at 500 °C promotes planar growth. The resulting (111) platinum films exhibit a narrow rocking curve full width at half maximum of 0.004°, a surface roughness of 0.20 nm, and conductivity of 8.99 × 106 S/m simultaneously—reaching metrics that are not currently available by other deposition methods. The e-beam deposition methodology developed in this study provides a route to increase the performance of platinum as a conductive substrate.

Multiple Resonance Quasi-fluorescence from BN-Doped Aromatic Compounds Modified with "Naphthalene" Units Approaches the BT.2020 Green Light Standard.

Developing fluorophores that conform to the Broadcast Service Television 2020 (BT.2020) standard presents a formidable challenge. Here, we propose an innovative approach that integrates two and three-boron/nitrogen (BN2)-embedded [4]helicene subunits with naphthalene, resulting in the synthesis of two novel narrowband bright green quasi-fluorescent emitters, NT-2B and NT-3B for ultra-high-definition displays. These emitters exhibit minimal reorganization energy and Huang-Rhys factor, emitting at 510 and 511 nm in dilute toluene solution with exceptionally narrow full width at half maximum values of 15 and 14 nm, respectively. Notably, NT-2B demonstrates an impressive photoluminescence quantum yield of 92.5 %, rapid radiative decay rate, and slow non-radiative decay rate. Owing to their narrowband emission characteristics and outstanding optoelectronic properties, corresponding OLEDs based on NT-2B demonstrate a high external quantum efficiency of 30.6 %, with an FWHM value of 21.5 nm and a CIEy of 0.74, positioning it as one of the leading narrow-band green emitters.

Multiple Resonance Quasi‐fluorescence from BN‐Doped Aromatic Compounds Modified with “Naphthalene” Units Approaches the BT.2020 Green Light Standard

AbstractDeveloping fluorophores that conform to the Broadcast Service Television 2020 (BT.2020) standard presents a formidable challenge. Here, we propose an innovative approach that integrates two and three‐boron/nitrogen (BN2)‐embedded [4]helicene subunits with naphthalene, resulting in the synthesis of two novel narrowband bright green quasi‐fluorescent emitters, NT‐2B and NT‐3B for ultra‐high‐definition displays. These emitters exhibit minimal reorganization energy and Huang–Rhys factor, emitting at 510 and 511 nm in dilute toluene solution with exceptionally narrow full width at half maximum values of 15 and 14 nm, respectively. Notably, NT‐2B demonstrates an impressive photoluminescence quantum yield of 92.5 %, rapid radiative decay rate, and slow non‐radiative decay rate. Owing to their narrowband emission characteristics and outstanding optoelectronic properties, corresponding OLEDs based on NT‐2B demonstrate a high external quantum efficiency of 30.6 %, with an FWHM value of 21.5 nm and a CIEy of 0.74, positioning it as one of the leading narrow‐band green emitters.