Search Results (67)

The study presents an engineering solution for maintaining traffic flow during road and utility operations, such as trench excavation. The analysis of existing organizational and technical approaches, along with global experience in temporary bridge use, showed that most foreign analogs were developed for military purposes and are not fully suitable for urban conditions in Kazakhstan and CIS countries. As an alternative solution, the development of a mobile overpass adapted for operation in dense urban environments is proposed. The present study continues earlier research focused on optimizing the placement of mobile overpass supports while accounting for the nonlinear deformation behavior of the soil foundation. At the previous stage, a rational distance between the supports and the trench edge was substantiated, and horizontal soil deformations were reduced. In the current study, the primary focus is on the design of the undercarriage, which determines the mobility, stability, and operational feasibility of the structure. A morphological analysis and synthesis method is applied to select a rational configuration of the undercarriage. A 3D model and a 1:4 scale test bench were developed, followed by load tests of 50–200 kg. The maximum deflection of −1.19 mm at 200 kg demonstrated an almost linear deformation pattern. The constructed regression model ($R^2=0.97$) confirmed the accuracy and reliability of the design. The developed mobile overpass is versatile, cost-effective, and practical, improving the resilience of urban transport infrastructure, reducing traffic congestion during roadworks, and creating a foundation for serial production in Kazakhstan and CIS countries. Full article

Wildland fire behaviour is strongly governed by the coupled effects of wind and terrain slope, yet the literature remains fragmented across experimental, empirical, mathematical, and physics-based modelling traditions. A systematic scoping review with narrative synthesis was performed (Web of Science, Scopus, and Google Scholar plus citation chaining), screening studies for explicit wind–slope treatment with reported forcings and outcomes. Across more than 150 studies, slope benches, wind tunnels, trenches/canyons, and field burns show that upslope–wind alignment promotes flame attachment and a shift from radiation-led to convection-led preheating (often near 20–30° slopes and moderate winds), whereas opposing or downslope forcing lifts flames and suppresses spread; confined geometries can trigger eruptive acceleration. Mathematical analogues and empirical models provide fast predictions using compact wind/slope modifiers and enable scenario and burn-probability mapping but typically prescribe coupling and miss regime transitions. Physics-based LES/CFD and coupled atmosphere–fire systems resolve terrain–flow feedback sand can yield reduced-order laws suitable for embedding into operational tools, albeit at higher computational cost and with validation gaps. Benchmarks are consolidated, approaches are compared using a common rubric (fidelity, validation, applicability, cost, and operational utility), and priorities are identified for cross-scale datasets, firebrand transport in complex terrain, and real-time coupled prediction. Full article

This study addresses the problem of traffic congestion in large cities caused by long-term repairs of underground utility networks. An innovative mobile overpass is considered, which combines the functions of a vehicle and a temporary bridge, allowing passenger cars up to 3.5 t to pass directly over repair trenches without detours. The research focuses on optimizing the placement of overpass supports relative to the trench edge to reduce soil deformation and prevent trench wall instability. A numerical methodology is developed in ANSYS Workbench that integrates finite element analysis of the soil-support system with parametric optimization using the nonlinear Drucker–Prager elastoplastic model. The soil parameters are obtained from oedometer compression tests (KPr-1M) and direct shear tests (PSG-2M) on clayey soils and then used to calibrate the numerical model. The optimization results show that the optimal distance from the trench wall to the overpass support is $L_{\min } = 2.78$ m, which is 13.5% greater than the initial design value. This modification reduces the maximum horizontal displacement of the trench wall by more than a factor of two and ensures compliance with the displacement criteria. Comparison between experimental and numerical compression curves yields an average deviation of 37.55%, with errors below 5% at higher stress levels, confirming that the Drucker–Prager model is suitable for engineering optimization of mobile overpass support placement on similar soils. The proposed methodology can be applied to the design and verification of temporary bridge systems operating above utility trenches in urban environments. Full article

Integrated Electrical Resistivity Imaging (ERI) and Induced Polarization (IP) studies were performed to identify potential tin (Sn) mineralization prospects in the Eastern Tin Belt of Peninsular Malaysia. A total of 23 profiles were obtained utilizing a Schlumberger configuration, generating resistivity and chargeability sections employed to delineate weathering structures, lithological connections, and structurally regulated anomalies. ERI models consistently delineate a three-tier subsurface structure consisting of conductive soil/alluvial deposits (5–300 Ωm), weathered bedrock (300–1500 Ωm), and resistive fresh bedrock (>1500 Ωm), featuring undulating basement relief beneath floodplain layers. IP data indicate localized, often pronounced chargeability anomalies (~5–40 ms; locally reaching ~50 ms), interpreted as corridors influenced by fractures and veins, especially when they align with significant resistivity contrasts at metamorphic–granitic boundaries and intrusive contacts. The integration of fence diagrams in the alluvial-over-granite zone reveals laterally consistent chargeability peaks at the alluvial–bedrock interface, suggesting enduring subsurface conduits. XRF examination of quartz-vein samples verifies Sn enrichment (599–717 ppm), corroborating a granite-related vein/alteration hypothesis and indicating possible isolated greisenized zones within the weathered granite. The integrated ERI–IP analysis identifies priority targets for subsequent trenching and borehole drilling to verify an anomaly’s origins and evaluate Sn grade and continuity. Full article

With the rapid increase in municipal solid waste and the associated production of incineration fly ash (IFA) in Taiwan, sustainable utilization of industrial by-products has become a pressing concern. This study evaluates the mechanical, environmental, and structural performance of ultra-high-performance concrete (UHPC) incorporating water-quenched slag (WQS) and IFA as partial replacements for cement or quartz powder. Laboratory-scale specimens were tested for compressive and flexural strength, followed by full-scale load-bearing tests on trench covers (60 × 35 × 4 cm) and manhole covers (120 × 60 × 5 cm) with varying steel fiber contents and welded steel mesh reinforcement. Mechanical behavior, heavy-metal leaching (TCLP), carbon emissions, and life cycle impact assessment (LCIA) were examined. The results show that WQS maintained or enhanced strength, while IFA caused strength loss and surface corrosion due to gas release during hydration. Trench covers with 15% WQS achieved the highest peak load (14,733 kg), exceeding heavy-traffic requirements, whereas IFA-based covers met the 10-ton standard but showed corrosion. Manhole covers did not reach the 75-ton design load, indicating applicability only for light or non-traffic areas. All UHPC mixes immobilized heavy metals within regulatory limits, and partial cement replacement reduced the carbon footprint by 60–120 kg CO₂e/m³. LCIA further indicated that 20% IFA replacement provided the greatest overall environmental benefit. In conclusion, WQS-incorporated UHPC offers reliable structural and environmental performance, while IFA requires pretreatment or modification to ensure long-term durability. Full article

Laser trepan drilling and laser helical drilling are typical methods for fabrication of micro through-holes through scanning laser beam. In the drilling process, the subsequent laser pulse may be occluded by the edge and the sputter deposition at the edge of the previous drilled trench. Dynamic focus feeding and widening path can be employed to lessen the occlusion effect and both of them are always employed in laser helical drilling. However, Widening the trench needs to remove more volume of material and may bring certain negative effects such as lowering the recoil pressure as well as less splashing melt due to the limited constraint of trench wall. The effects of dynamic feeding the focal plane and widening the scanning path on the quality and efficiency in the nanosecond laser drilling process were investigated through laser drilling holes with diameter of 500 μm on a 300 μm thick GH4169 plate. Results show that dynamic focus feeding is beneficial in both drilling efficiency and drilling quality. Through laser helical drilling with dynamic focus feeding, micro through-hole can be fabricated in 5 s, and both smaller tilting angle of 0.073 rad and smaller heat-affected zone of 0.63 mm in radius can be obtained. Widening scanning path is helpful to perforating rapidly but leads to much more recast layer coating. the quality of the micro through-holes depends not only on the utilization efficiency of the laser energy, but also on high temperature spatter deposition, which is the source of the difference between different drilling strategies. Due to the low cost in equipment and the better hole quality, the laser drilling, especially laser helical drilling, has potential applications ranging from aerospace fields to normal fields such as the agricultural machinery industry. Full article

Graphoepitaxial directed self-assembly (DSA) of block copolymers (BCPs) has emerged as a promising strategy for sub-30 nm line spacing patterning in semiconductor nanofabrication. Among the available BCP systems, polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA) has been extensively utilized due to its well-characterized phase behavior and compatibility with standard lithographic processes. However, achieving a high-fidelity pattern with PS-b-PMMA remains challenging, owing to its limited etch contrast and reliance on UV-assisted degradation for PMMA removal. In this study, we report the synthesis of an acid-cleavable lamellar BCP, PS-N=CH-PMMA, incorporating a dynamic Schiff base (-N=CH-) linkage at the junction. This functional design enables UV-free wet etching, allowing selective removal of PMMA domains using glacial acetic acid. The synthesized copolymers retain the self-assembly characteristics of PS-b-PMMA and form vertically aligned lamellar nanostructures, with domain spacings tunable from 36.1 to 40.2 nm by varying the PMMA block length. When confined within 193i-defined trench templates with a critical dimension (CD) of 55 nm (trench width), these materials produced well-ordered one-space-per-trench patterns with interline spacings tunable from 15 to 25 nm, demonstrating significant line spacing shrinkage relative to the original template CD. SEM and FIB-TEM analyses confirmed that PS-N=CH-PMMA exhibits markedly improved vertical etch profiles and reduced PMMA residue compared to PS-b-PMMA, even without UV exposure. Furthermore, Ohta–Kawasaki simulations revealed that trench sidewall angle critically influences PS distribution and residual morphology. Collectively, this work demonstrates the potential of dynamic covalent chemistry to enhance the wet development fidelity of BCP lithography and offers a thermally compatible, UV-free strategy for sub-30 nm nanopatterning. Full article

High aspect ratio (HAR) sample-induced aberrations seriously affect the topography measurement for the bottom of the microstructure by coherence scanning interferometry (CSI). Previous research proposed an aberration compensating method using deformable mirrors at the conjugate position of the pupil. However, it failed to compensate for the shift-variant aberrations introduced by the HAR hybrid trench array composed of multiple trenches with different parameters. Here, we propose a computational aberration correction method for measuring the topography of the HAR structure by the particle swarm optimization (PSO) algorithm without constructing a database and prior knowledge, and a phase filter in the spatial frequency domain is constructed to restore interference signals distorted by shift-variant aberrations. Since the aberrations of each sampling point are basically unchanged in the field of view corresponding to a single trench, each trench under test can be considered as a separate isoplanatic region. Therefore, a multi-channel aberration correction scheme utilizing the virtual phase filter based on isoplanatic region segmentation is established for hybrid trench array samples. The PSO algorithm is adopted to derive the optimal Zernike polynomial coefficients representing the filter, in which the interference fringe contrast is taken as the optimization criterion. Additionally, aberrations introduce phase distortion within the 3D transfer function (3D-TF), and the 3D-TF bandwidth remains unchanged. Accordingly, we set the non-zero part of the 3D-TF as a window function to preprocess the interferogram by filtering out the signals outside the window. Finally, experiments are performed in a single trench sample and two hybrid trench array samples with depths ranging from 100 to 300 μm and widths from 10 to 30 μm to verify the effectiveness and accuracy of the proposed method. Full article

Accurate localization of buried water pipelines in rural areas is crucial for maintenance and leak management but is often hindered by outdated maps and the limitations of traditional geophysical methods. This study aimed to develop and validate a multi-source remote-sensing workflow, integrating UAV (unmanned aerial vehicle)-borne near-infrared (NIR) surveys, multi-temporal Sentinel-2 imagery, and historical Google Earth orthophotos to precisely map pipeline locations and establish a surface baseline for future monitoring. Each dataset was processed within a unified least-squares framework to delineate pipeline axes from surface anomalies (vegetation stress, soil discoloration, and proxies) and rigorously quantify positional uncertainty, with findings validated against RTK-GNSS (Real-Time Kinematic—Global Navigation Satellite System) surveys of an excavated trench. The combined approach yielded sub-meter accuracy (±0.3 m) with UAV data, meter-scale precision (≈±1 m) with Google Earth, and precision up to several meters (±13.0 m) with Sentinel-2, significantly improving upon inaccurate legacy maps (up to a 300 m divergence) and successfully guiding excavation to locate a pipeline segment. The methodology demonstrated seasonal variability in detection capabilities, with optimal UAV-based identification occurring during early-vegetation growth phases (NDVI, Normalized Difference Vegetation Index ≈ 0.30–0.45) and post-harvest periods. A Sentinel-2 analysis of 221 cloud-free scenes revealed persistent soil discoloration patterns spanning 15–30 m in width, while Google Earth historical imagery provided crucial bridging data with intermediate spatial and temporal resolution. Ground-truth validation confirmed the pipeline location within 0.4 m of the Google Earth-derived position. This integrated, cost-effective workflow provides a transferable methodology for enhanced pipeline mapping and establishes a vital baseline of surface signatures, enabling more effective future monitoring and proactive maintenance to detect leaks or structural failures. This methodology is particularly valuable for water utility companies, municipal infrastructure managers, consulting engineers specializing in buried utilities, and remote-sensing practitioners working in pipeline detection and monitoring applications. Full article

In this study, a novel silicon carbide (SiC) double-trench MOSFET (DT-MOS) combined Schottky barrier diode (SBD) and MOS-channel diode (MCD) is proposed and investigated using TCAD simulations. The integrated MCD helps inactivate the parasitic body diode when the device is utilized as a freewheeling diode, eliminating bipolar degradation. The adjustment of SBD position provides an alternative path for reverse conduction and mitigates the electric field distribution near the bottom source trench region. As a result of the Schottky contact adjustment, the reverse conduction characteristics are less influenced by the source oxide thickness, and the breakdown voltage (BV) is largely improved from 800 V to 1069 V. The gate-to-drain capacitance is much lower due to the removal of the bottom oxide, bringing an improvement to the turn-on switching rise time from 2.58 ns to 0.68 ns. These optimized performances indicate the proposed structure with both SBD and MCD has advantages in switching and breakdown characteristics. Full article

This study aims to address the challenge of backfill compaction in the confined spaces of municipal utility tunnel trenches and to develop an environmentally friendly, zero-cement-based backfill material. The research focuses on the excavation slag soil from a utility tunnel project in Handan. An alkali-activated industrial-solid-waste-excavated slag-soil-based controllable low-strength material (CLSM) was developed, using NaOH as the activator, a slag–fly ash composite system as the binder, and steel slag-excavated slag as the fine aggregate. The effects of the water-to-solid ratio (0.40–0.45) and the binder-to-sand ratio (0.20–0.40) on CLSM fluidity were studied to determine optimal values for these parameters. Additionally, the influence of excavated soil content (45–65%), slag content (30–70%), and NaOH content (1–5%) on fluidity (flowability and bleeding rate) and mechanical properties (3-day, 7-day, and 28-day unconfined compressive strength (UCS)) was investigated. The results showed that when the water-to-solid ratio is 0.445 and the binder-to-sand ratio is 0.30, the material meets both experimental and practical requirements. CLSM fluidity was mainly influenced by the excavated soil and slag contents, while NaOH content had minimal effect. The unconfined compressive strength at different curing ages was negatively correlated with the excavated soil content, while it was positively correlated with slag and NaOH content. Based on these findings, the preparation of “zero-cement” CLSM using industrial solid waste and excavation slag is feasible. For trench backfill projects, a mix of 50–60% excavated soil, 40–60% slag, and 3–5% NaOH is recommended for optimal engineering performance. CLSM is a new type of green backfill material that uses excavated soil and industrial solid waste to prepare alkali-activated materials. It can effectively increase the amount of excavated soil and alleviate energy consumption. This is conducive to the reuse of resources, environmental protection, and sustainable development. Full article

The Gobi Wall is a 321 km-long structure made of earth, stone, and wood, located in the Gobi highland desert of Mongolia. It is the least understood section of the medieval wall system that extends from China into Mongolia. This study aims to determine its builders, purpose, and chronology. Additionally, we seek to better understand the ecological implications of constructing such an extensive system of walls, trenches, garrisons, and fortresses in the remote and harsh environment of the Gobi Desert. Our field expedition combined remote sensing, pedestrian surveys, and targeted excavations at key sites. The results indicate that the garrison walls and main long wall were primarily constructed using rammed earth, with wood and stone reinforcements. Excavations of garrisons uncovered evidence of long-term occupation, including artifacts spanning from 2nd c. BCE to 19th c. CE. According to our findings, the main construction and usage phase of the wall and its associated structures occurred throughout the Xi Xia dynasty (1038–1227 CE), a period characterized by advanced frontier defense systems and significant geopolitical shifts. This study challenges the perception of such structures as being purely defensive, revealing the Gobi Wall’s multifunctional role as an imperial tool for demarcating boundaries, managing populations and resources, and consolidating territorial control. Furthermore, our spatial and ecological analysis demonstrates that the distribution of local resources, such as water and wood, was critical in determining the route of the wall and the placement of associated garrisons and forts. Other geographic factors, including the location of mountain passes and the spread of sand dunes, were strategically utilized to enhance the effectiveness of the wall system. The results of this study reshape our understanding of medieval Inner Asian imperial infrastructure and its lasting impact on geopolitical landscapes. By integrating historical and archeological evidence with geographical analysis of the locations of garrisons and fortifications, we underscore the Xi Xia kingdom’s strategic emphasis on regulating trade, securing transportation routes, and monitoring frontier movement. Full article

This paper presents a comprehensive experimental study on the mix design and performance of permeable concrete for geotechnical applications, focusing on its hydraulic conductivity, durability, and filter properties. Characterized by high porosity and minimal or no fine aggregates, classical pervious concretes are effectively utilized in various civil and environmental engineering applications, including drainage systems and erosion control. This research examines the influence of the particle size distribution of aggregates on the filter properties of permeable concrete for applications in geotechnical engineering (draining piles, deep trench drains, and draining backfill). It emphasizes the importance of resistance to clogging to maintain adequate residual hydraulic conductivity and to prevent the internal erosion of soils into which permeable concrete drains are installed. The experimental results indicate that including sand in the aggregates strongly enhances the filtering capacity of pervious concrete. These findings suggest that if the mix design of permeable concrete is developed considering the grain size distribution of the base soils, the concrete will meet long-term drainage requirements (sufficient residual hydraulic conductivity), exhibit good resistance to physical clogging, provide excellent protection for the base soils against internal erosion, and contribute to the overall stability of geotechnical systems. Full article

The transition of SiC MOSFET structure from planar to trench-based architectures requires the optimization of gate dielectric layers to improve device performance. This study utilizes a range of characterization techniques to explore the interfacial properties of ZrO₂ and SiO₂/ZrO₂ gate dielectric films, grown via atomic layer deposition (ALD) in SiC epitaxial trench structures to assess their performance and suitability for device applications. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements showed the deposition of smooth film morphologies with roughness below 1 nm for both ZrO₂ and SiO₂/ZrO₂ gate dielectrics, while SE measurements revealed comparable physical thicknesses of 40.73 nm for ZrO₂ and 41.55 nm for SiO₂/ZrO₂. X-ray photoelectron spectroscopy (XPS) shows that in SiO₂/ZrO₂ thin films, the binding energies of Zr 3d_5/2 and Zr 3d_3/2 peaks shift upward compared to pure ZrO₂. Electrical characterization showed an enhancement of E_BR (3.76 to 5.78 MV·cm⁻¹) and a decrease of I_{ON_EBR} (1.94 to 2.09 × 10⁻³ A·cm⁻²) for the SiO₂/ZrO₂ stacks. Conduction mechanism analysis identified suppressed Schottky emission in the stacked film. This indicates that the incorporation of a thin SiO₂ layer effectively mitigates the small bandgap offset, enhances the breakdown electric field, reduces leakage current, and improves device performance. Full article

This work introduces a novel temperature-triggered threshold voltage shift (T3VS) method to study the energy-dependent $D_{it}$ distribution close to the conduction band edge in commercial 1.2 kV 4H-SiC MOSFETs with planar and trench gate structures. Traditional $D_{it}$ extraction methodologies are complicated and require sophisticated instrumentation, complex analysis, and/or prior information related to the device design and fabrication, which is generally unavailable to the consumers of commercial devices. This methodology merely utilizes the transfer characteristics of the device and is straightforward to implement. The $D_{it}$ analysis using the T3VS method shows that trench devices have significantly lower $D_{it}$ in comparison to the planar devices, making them more reliable and efficient in practical applications. Furthermore, this study examines the impact of a novel room temperature gate oxide screening methodology called screening with adjustment pulse (SWAP) on the $D_{it}$ distribution in commercial planar MOSFETs, utilizing the proposed T3VS method. The result demonstrates that the SWAP technique is aggressive in nature and can introduce new defect states close to the conduction band edge. Hence, additional care is needed during screening optimization to ensure the reliability and usability of the screened devices in the consequent applications. Full article