Search Results (55)

The U-shaped Metal-Oxide-Semiconductor Field-Effect Transistor (UMOS or trench FET) is one of the most widely used semiconductor power devices worldwide, increasingly replacing the traditional vertical double-diffused MOSFET (DMOSFET) in various applications due to its superior electrical performance. However, a detailed experimental comparison of ion-induced Single-Event Burnout (SEB) in similarly rated silicon (Si) UMOS and DMOS devices remains lacking. This study presents a comprehensive experimental comparison of ion-induced charge collection mechanisms and SEB susceptibility in similarly rated Si UMOS and DMOS devices. Charge collection mechanisms due to alpha particles from ²⁴¹Am radiation source are analyzed, and SEB cross sections induced by heavy ions from particle accelerators are directly compared. The implications of the unique gate structure of Si UMOSFETs on their reliability in harsh radiation environments are discussed based on technology computer-aided design (TCAD) simulations. Full article

The present study analyzes the hydrodynamic performance of an asymmetric offshore Oscillating Water Column device positioned in close proximity to multiple bottom standing and fully submerged breakwaters and trenches. The breakwaters and trenches are located on the leeward side of the Oscillating Water Column device. The structures are investigated in combination with a shore-fixed vertical wall. The analysis is carried out using the Boundary Element Method based on the linear potential flow theory. The results are compared with the existing analytical, numerical, and experiment results available in the literature. The effects of the various shape parameters of the submerged breakwaters/trenches and the shape parameters of the Oscillating Water Column device are investigated. The results show that the resonance effects on the efficiency performance increase as the number of breakwaters/trenches increases. The undulating bottom trench shape is effective in improving the efficiency of the Oscillating Water Column device compared to the breakwater. The efficiency bandwidth is greater in the case of a rectangular trench than in the case of a parabolic- or triangular-shaped trench. In addition, the first peak value in the efficiency curve for a lower frequency is higher in the case of a larger-draft Oscillating Water Column device front wall compared to that of the rear wall. This study demonstrates that in the long wave-length regime, a zero efficiency point is observed between two consecutive resonant peaks, whereas in the intermediate and short wave-length regimes, a trough and a zero efficiency point alternately occur between two consecutive resonance peaks. Various parameters relevant to the behavior of the Oscillating Water Column Wave Energy Converter, such as radiation susceptance, radiation conductance, hydrodynamic efficiency, and volume flux due to a scatter potential, are addressed. Full article

Human–wildlife conflict poses significant ecological and socio-economic challenges, particularly in rural communities where agriculture and livestock rearing form the backbone of livelihoods. Despite the growing importance of this issue, District Lakki Marwat remains an unexplored area of northwest Pakistan. This study aims to fill this gap by systematically assessing the status, economic impacts, and community perceptions of five wildlife species: wild boar (Sus scrofa), grey wolf (Canis lupus), golden jackal (Canis aureus), striped hyena (Hyaena hyaena), and red fox (Vulpes vulpes). Using semi-structured surveys with 117 respondents, we analyzed species prevalence, perceived danger levels, crop damage patterns, and predation impacts on livestock and poultry. The findings revealed that wild boars were identified as the primary contributors to agricultural damage, with total annual crop losses surpassing the economic impacts attributed to the studied carnivores. On average, each surveyed household experienced an annual loss of PKR 4510.38. For the 39% of households reporting crop damage, the annual loss per reported household was PKR 11,727, which was higher than the average annual loss across all households, underscoring the severity of the impact on those specifically affected by the wild boar-related crop damage. Notably, community attitudes were most negative toward wild boars, a pattern driven by the economic burden of crop losses, challenging the conventional focus on carnivores as the primary conflict species. A Pearson’s $X^2$ test confirmed strong associations between species and perceived danger levels, while regression analysis demonstrated an association between crop damage and negative attitudes. Traditional deterrents like thorn fences were found ineffective against wild boars. More advanced methods, including game-proof fencing, trenches, bio-fencing, crop rotation, audio and visual deterrents, taste and order repellents, and watchtowers combined with group vigilance, are recommended to reduce crop damage. Integrating these approaches with community-based education, habitat management, and government-supported compensation schemes can mitigate wild boar impacts. This study contributes new insights into multi-species HWC dynamics, demonstrating that community perceptions are primarily shaped by the economic impact of a species, regardless of whether it is a carnivore or an omnivore. The attitudes of local communities are driven by the financial losses incurred, rather than the species' behavior or ecological role. This study underscores the need for collaborative efforts to reduce human–wildlife conflict, foster coexistence, and ensure ecological balance in vulnerable rural areas. Full article

To improve the soil loosening effects of degraded grasslands, this study investigates the performance of a bionic loosening shovel designed based on the claws of prairie zokor. A single-factor simulation test of the bionic loosening shovel was conducted using EDEM software to analyze the effects of loosening depth (H) and operating speed (V) on key parameters, including the ridge disturbance area (A_s), furrow disturbance area (A_f), loosening resistance (F_r), and trench specific resistance (F_c). Additionally, field tests were performed to validate the simulation results of the bionic loosening shovel. The findings indicate that the difference ratio (D_a1) between the simulated and test values for the bionic loosening shovel remained consistently low, confirming the reliability of the simulation model in predicting variations in response parameters. Furthermore, comparative field tests were conducted to evaluate the loosening performance of the bionic loosening shovel against standard loosening shovels (the diamond-shaped loosening shovel and the arrow-shaped loosening shovel). The results show that the bionic loosening shovel achieved the lowest values for A_s, A_f, and F_r under the same operating parameters. However, its effect on improving A_f was limited. These findings provide valuable technical support for the enhancement and optimization of loosening shovels for degraded grasslands. Full article

In this work, the attenuation of surface seismic waves from large-scale phononic metamaterials is numerically studied. The proposed metamaterials consist of rectangular trenches that form either I-shaped or T-shaped cavities embedded at the ground surface. The numerical investigation includes the study of the response of the proposed structures for different values of their geometric parameters. In addition, modifications of the proposed structures where heavy cores coated with a soft material were considered in the cavities were also numerically studied. For a more realistic numerical approach, the transmission spectrum of a selected large-scale phononic metamaterial was also investigated in a suitable half-space numerical scheme. The results of the present research showed that the studied large-scale metastructures could be a very promising potential candidate for seismic shielding applications for the protection of existing urban or countryside structures. The proposed metamaterials are low in cost and easy to construct for the protection of existing buildings, critical infrastructures, or even entire urban areas without need for any kind of intervention at them, therefore providing an effective solution in the field of seismic isolation. Full article

During the operation of a shaped hole seed-metering device, poor seed-filling quality and inconsistent seed-casting points lead to poor seed spacing uniformity, especially in a one-chamber double-row seed-metering device. To solve this problem, a soybean double-row seed-metering device with double-beveled seed guide groove was designed to ensure a high single-seed rate and seed-casting point consistency. Through the theoretical analysis of the working process of the seed-metering device, dynamic and kinematic models of the seeds were established, and the main structural parameters of the seed discharge ring, triage convex ridge, shaped hole, and seed guide groove were determined. The main factors affecting the seeding performance were obtained as the following: the inclination angle of the triage convex ridge, the radius of the shaped hole, and the depth of the seed guide groove. A single-factor test was carried out by discrete element simulation to obtain the inclination angle of the triage convex ridge α₃ = 29°, the radius of the shaped hole r₁ = 4.16–4.5 mm, and the depth of the seed guide groove l₁ = 0.49–1.89 mm. A two-factor, five-level, second-order, orthogonal rotation combination test was conducted to further optimize the structural parameters of the seed-metering device. The two test factors were the radius of the shaped hole and the depth of the seed guide groove, and the evaluation indices were the qualified rate, replay rate, and missed seeding rate. The results showed that the optimal combinations of the structural parameters were the radius of the shaped hole r₁ = 4.33 mm and the depth of the seed guide groove l₁ = 1.20 mm. Subsequent bench testing demonstrated that the seed discharge’s qualified rate was above 94% at operating speeds of 6–10 km/h, and the seeding performance was stable. The final results of the soil trench test showed that the seed-metering device exhibited a qualified rate of 93.31%, replay rate of 2.04%, and missed seeding rate of 4.65% at an operating speed of 8 km/h. This research outcome may serve as a valuable reference and source of inspiration for the innovative design of precision seed-metering devices. Full article

In this paper, we present an optimization of the planar manufacturing scheme for stretch-free, shape-induced metal interconnects to simplify fabrication with the aim of maximizing the flexibility in a structure regarding stress and strain. The formation of trenches between silicon islands is actively used in the lithographic process to create arc shape structures by spin coating resists into the trenches. The resulting resist form is used as a template for the metal lines, which are structured on top. Because this arc shape is beneficial for the flexibility of these bridges. The trench depth as a key parameter for the stress distribution is investigated by applying numerical simulations. The simulated results show that the increase in penetration depth of the metal bridge into the trench increases the tensile load which is converted into a shear force Q(x), that usually leads to increased strains the structure can generate. For the fabrication, the filling of the trenches with resists is optimized by varying the spin speed. Compared to theoretical resistance, the current–voltage measurements of the metal bridges show a similar behavior and almost every structural variation is capable of functioning as a flexible electrical interconnect in a complete island-bridge array. Full article

The handling of the remnants of rice crops in the field is not an easy operation, and farmers prefer burning, which causes air pollution, smog, and disease. This research reports the development of a novel precision crop seeder by handling the remnants of previous crops through mechanization. The precision seeder performed multiple operations in a single path, viz, chop residues, incorporate into soil, make mini trenches, and sow wheat with fertilizer application. The precision seeder has a 2040 mm working width, and specially designed C-type blades are used to shred the crop residue. A multiple-speed gearbox with a gear ratio of 1:0.52 is installed, with a further set of spur gears with 16, 18, and 20 teeth that provide 225, 250, 310, and 350 RPMs to the main rotor. In the middle of the seeder, after the main rotor shaft, 11 V-shaped trencher plates are fixed on the trencher roller for the making of trenches. The trencher roller is powered by star wheels, which showed good results. A zero-tillage-type sharp tip edge novel seeder unit was developed for the precise placement of seed and fertilizer. Seed and fertilizer were placed into the mini trenches through 11 seeder units through a ground wheel calibration system. The field capacity of the precision seeder was 0.408 ha/h and the operational cost was calculated 40.68 USD/ha. The seeder showed good results, with the production of 5028 kg/ha compared to conventional methods. The precision seeder provides a mechanized solution for wheat sowing with minimal operational costs by enhancing organic matter in soil with 13% more yield. Full article

A silicon carbide (SiC) SGT MOSFET featuring a “一”-shaped P+ shielding region (PSR), named SPDT-MOS, is proposed in this article. The improved PSR is introduced as a replacement for the source trench to enhance the forward performance of the device. Its improvement consists of two parts. One is to optimize the electric field distribution of the device, and the other is to expand the current conduction path. Based on the improved PSR and grounded split gate (SG), the device remarkably improves the conduction characteristics, gate oxide reliability, and frequency response. Moreover, the integrated sidewall Schottky barrier diode (SBD) prevents the inherent body diode from being activated and improves the reverse recovery characteristics. As a result, the gate-drain capacitance, gate charge, and reverse recovery charge (Q_rr) of the SPDT-MOS are 81.2%, 41.2%, and 90.71% lower than those of the DTMOS, respectively. Compared to the double shielding (DS-MOS), the SPDT-MOS exhibits a 20% reduction in on-resistance and an 8.1% increase in breakdown voltage. Full article

A SiC double-trench MOSFET embedded with a lower-barrier diode and an L-shaped gate-source in the gate trench, showing improved reverse conduction and an improved switching performance, was proposed and studied with 2-D simulations. Compared with a double-trench MOSFET (DT-MOS) and a DT-MOS with a channel-MOS diode (DTC-MOS), the proposed MOS showed a lower voltage drop (V_F) at I_S = 100 A/cm², which can prevent bipolar degradation at the same blocking voltage (BV) and decrease the maximum oxide electric field (E_mox). Additionally, the gate–drain capacitance (C_gd) and gate–drain charge (Q_gd) of the proposed MOSFET decreased significantly because the source extended to the bottom of the gate, and the overlap between the gate electrode and drain electrode decreased. Although the proposed MOS had a greater R_on,sp than the DT-MOS and DTC-MOS, it had a lower switching loss and greater advantages for high-frequency applications. Full article

The Lac Fallère area in the upper Clusellaz Valley (tributary of the middle Aosta Valley) is shaped in micaschist and gneiss (Mont Fort Unit, Middle Penninic) and in calcschist and marble (Aouilletta Unit, Combin Zone). Lac Fallère exhibits an elongated shape and is hosted in a WSW–ENE-trending depression, according to the slope direction. This lake also shows a semi-submerged WSW–ENE rocky ridge that longitudinally divides the lake. This evidence, in addition to the extremely fractured rocks, indicates a wide, deep-seated gravitational slope deformation (DSGSD), even if this area is not yet included within the regional landslide inventory of the Aosta Valley Region. The Lac Fallère area also shows reliefs involved in glacial erosion (roches moutonnée), an extensive cover of subglacial sediments, and many moraines essentially referred to as Lateglacial. The DSGSD evolution in a glacial environment produced, as observed in other areas, effects on the facies of Quaternary sediments and the formation of a lot of wide moraines. Glacial slope sectors and lateral moraines displaced by minor scarps and counterscarps, and glaciers using trenches forming several arched moraines, suggest an interplay between glacial and gravitational processes, which share part of their evolution history. Full article

Circular diaphragm walls are increasingly being used in ultra-deep foundation pits due to their arch-shaped bearing system, which provides reasonable structural support. The trench walls that form the circular ground connection wall are typically double-angled in shape, and their stability analysis remains a challenge. In this paper, an instability model for double-angled trench walls based on 3D sliding body analysis is proposed. The objective of this paper is to determine the minimum amount of slurry needed to maintain the integrity of the trench wall. The results show that the center of symmetry on the inside of the wall is the most vulnerable to damage, followed by the inside corner, and then the center and corner on the outside. The consideration of sliding bodies in overall and local stability calculations for double-angled trench wall shapes can provide a reasonable stability assessment. Full article

High-purity germanium detectors, widely employed in fields such as aerospace applications based on radiation detection principles, have garnered attention due to their broad detection range and fast response time. However, these detectors often require larger sensitive area volumes to achieve larger signals and higher detection efficiency. Additionally, the large distance between the electrodes contributes to an issue of incomplete charge collection, which significantly restricts their application in space applications. To enhance the electrical performance of high-purity germanium detectors, this study introduces a strategy: designing the detector’s cathode electrode into a 3D trench shape with nested complementary cathodes. This design greatly reduces the electrode spacing, endowing the detector with superior electrical characteristics, such as a smaller dead zone and improved charge collection efficiency. Performance simulations of the novel detector structure were conducted using the semiconductor device simulation software Sentaurus TCAD (2019.03). The simulation results confirmed that the nested complementary 3D trench electrode high-purity germanium detector exhibits excellent electrical features, including a larger sensitive area volume, rapid charge collection, and good cell isolations. This approach has the potential to effectively expand the application scenarios of high-purity germanium detectors. Depending on different operational environments and requirements, nested complementary 3D trench electrode high-purity germanium detectors of appropriate structural dimensions can be chosen. The experimental findings of this study hold a significant reference value for enhancing the overall structure of high purity germanium detectors and facilitating their practical application in the future. Full article

The quality factor of microelectromechanical resonators is a crucial performance metric and has thus been the subject of numerous studies aimed at maximizing its value by minimizing the anchor loss. This work presents a study on the effect of elastic wave reflectors on the quality factor of MEMS clamped–clamped flexural beam resonators. The elastic wave reflectors are a series of holes created by trenches in the silicon substrate of the resonators. In this regard, four different shapes of arrayed holes are considered, i.e., two sizes of squares and two half circles with different directions are positioned in proximity to the anchors. The impact of these shapes on the quality factor is examined through both numerical simulations and experimental analysis. A 2D in-plane wave propagation model with a low-reflecting fixed boundary condition was used in the numerical simulation to predict the behavior, and the MEMS resonator prototypes were fabricated using a commercially available micro-fabrication process to validate the findings. Notably, the research identifies that half-circle-shaped holes with their curved sides facing the anchors yield the most promising results. With these reflectors, the quality factor of the resonator is increased by a factor of 1.70× in air or 1.72× in vacuum. Full article

In this study, the 1991 rock avalanche, in Touzhai, Zhaotong, Yunnan, China, was considered the study object. The investigation of the landslide accumulation body revealed that the Touzhai rock avalanche accumulation body has the characteristics of wide gradation and poor sorting. A combination of field investigations, indoor and outdoor experiments, and numerical simulations were used to invert the occurrence and spreading range of rock avalanche-debris flow hazards. To invert and analyze its dynamics and the crushing process, a three-dimensional discrete element modeling was performed on the real terrain data. Simulation results showed that the movement time of the numerically simulated Touzhai rock avalanche was approximately 200 s. After 50 s of movement, the peak velocity reached 32 m/s, and the velocity gradually decayed after the sliding mass rubbed violently against the valley floor and collided with the mountain. Due to the meandering nature of the gully, the sliding mass makes its way down the gully and constantly collides with the mountain, making particles appear to climb, with some particles being blocked by the valley. After 150 s of movement, the average velocity rate decreased substantially, and the landslide-avalanche debris reached the mouth of the trench. After 200 s of movement, the average sliding velocity tends to 0 m/s, where the avalanche debris tends to stop and accumulate. When the rock avalanche movement reaches the mouth of the gully, the avalanche debris spreads to the sides as it is no longer bounded by the hills on either side of the narrow gully, eventually forming a ‘trumpet-shaped’ accumulation, and the granular flow simulation matched the findings of the landslide site accumulation. Full article