Search Results (97)

Due to the complex spatial structure, dense tree distribution, and narrow passages in orchard environments, traditional path planning algorithms often struggle with large path deviations, frequent turning, and reduced navigational safety. In order to overcome these challenges, this paper proposes a hybrid path planning algorithm based on improved D* Lite for narrow forest orchard environments. The proposed approach enhances path feasibility and improves the robustness of the navigation system. The algorithm begins by constructing a 2D grid map reflecting the orchard layout and inflates the tree regions to create safety buffers for reliable path planning. For global path planning, an enhanced D* Lite algorithm is used with a cost function that jointly considers centerline proximity, turning angle smoothness, and directional consistency. This guides the path to remain close to the orchard row centerline, improving structural adaptability and path rationality. Narrow passages along the initial path are detected, and local replanning is performed using a Hybrid A* algorithm that accounts for the kinematic constraints of a differential tracked robot. This generates curvature-continuous and directionally stable segments that replace the original narrow-path portions. Finally, a gradient descent method is applied to smooth the overall path, improving trajectory continuity and execution stability. Field experiments in representative orchard environments demonstrate that the proposed hybrid algorithm significantly outperforms traditional D* Lite and KD* Lite-B methods in terms of path accuracy and navigational safety. The average deviation from the centerline is only 0.06 m, representing reductions of 75.55% and 38.27% compared to traditional D* Lite and KD* Lite-B, respectively, thereby enabling high-precision centerline tracking. Moreover, the number of hazardous nodes, defined as path points near obstacles, was reduced to five, marking decreases of 92.86% and 68.75%, respectively, and substantially enhancing navigation safety. These results confirm the method’s strong applicability in complex, constrained orchard environments and its potential as a foundation for efficient, safe, and fully autonomous agricultural robot operation. Full article

Multidrug-resistant (MDR) strains of Klebsiella pneumoniae present an acute threat as they continue to disseminate globally. Phage therapy has shown promise as a powerful approach to combat MDR infections, but narrow phage host ranges make development of broad acting therapeutics more challenging. The goal of this effort was to use in vitro directed evolution (the “Appelmans protocol”) to isolate K. pneumoniae phages with broader host ranges for improved therapeutic cocktails. Five myophages in the genus Jiaodavirus (family Straboviridae) with complementary activity were mixed and passaged against a panel of 11 bacterial strains including a permissive host and phage-resistant clinical isolates. Following multiple rounds of training, we collected phage variants displaying altered specificity or expanded host ranges compared with parental phages when tested against a 100 strain diversity panel of K. pneumoniae. Some phage variants gained the ability to lyse previously phage-resistant strains but lost activity towards previously phage-susceptible strains, while several variants had expanded activity. Whole-genome sequencing identified mutations and recombination events impacting genes associated with host tropism including tail fiber genes that most likely underlie the observed changes in host ranges. Evolved phages with broader activity are promising candidates for improved K. pneumoniae therapeutic phage cocktails. Full article

Background: African Swine Fever (ASF) is a viral hemorrhagic disease characterized by diverse clinical and pathological manifestations depending on the virulence of isolates/strains and the immunological status of pigs. The use of modified live viruses (MLVs) is currently the most common approach in developing vaccines against ASF. However, despite the availability of dozens of MLV candidates that meet basic safety and efficacy criteria—such as the absence of severe clinical signs and survival after challenge with a virulent strain—no broadly accepted vaccine has yet been developed. Here, we propose viremia testing as an essential criterion for evaluating candidate ASF vaccines, with levels exceeding 10⁴ HAD₅₀/TCID₅₀ and lasting longer than 21–28 days post vaccination considered unfavorable indicators. Methods: We analyzed ASF MLV vaccines obtained through the deletion of one, two, or more genes, focusing on viremia kinetics after vaccination and challenge with virulent ASFV strains. Post mortem data were used to assess viral persistence in organs. Results: Most MLV candidates, especially those with single-gene deletions, demonstrated relatively high viremia levels after vaccination and challenge. Viral persistence was frequently detected in organs upon necropsy. MLVs with an additional EP402R gene deletion showed low viremia after vaccination but high levels after challenge. Nevertheless, several candidates with favorable viremia profiles were identified, including those obtained via targeted deletions or serial passaging in cell cultures. Conclusions: Incorporating viremia assessment as a primary screening criterion can significantly narrow down the selection of promising MLV candidates and help accelerate the development of effective emergency vaccines for use in ASF-affected regions. Full article

Using the shield project of the Cai Cang Section tunnel of the Guangzhou Metro Line 13 to solve the problem that shield construction is difficult to start in a narrow space and it is easy to disturb the surrounding buildings and pipelines, the corresponding shield tunneling parameters, construction and transportation plans, residual soil management plans, and grouting reinforcement plans are designed. These are tailored according to different working conditions. Meanwhile, the MIDAS GTS 2022 numerical simulation software is applied to simulate and analyze the impact of shield tunneling construction on soil deformation, and to compare the effects before and after reinforcement of the soil layer during shield tunneling. The results show the amount of disturbance of building pipelines along the tunnel are effectively controlled by designing the corresponding shield tunneling parameters for three working conditions: contact reinforcement zone, entering reinforcement zone, and exiting reinforcement zone. In narrow spaces, three kinds of construction transportation modes (namely, horizontal transportation in the tunnel, translation transportation in the cross passage, and vertical transportation) ensure the smooth transportation of pipe segments and the smooth discharge of shield dregs. After the reinforced area is constructed, secondary grouting with cement mortar effectively reduces the erosion concrete segments by underground water. By comparing the deformation of the tunnel soil layer before and after reinforcement, it is found that the maximum surface deformation of the soil layer is significantly reduced after reinforcement. Specifically, the maximum settlement and maximum uplift are 0.782 mm and 1.87 mm respectively, which represent a reduction of 1.548 mm in the maximum surface settlement, and 0.16 mm in the maximum uplift compared with the unreinforced soil layer. This indicates that setting up a soil reinforcement zone during the initial launching stage can effectively reduce soil deformation. The Cai Cang Section tunnel shield project successfully completed the shield construction in a narrow space, which can be a reference and guide for similar projects. Full article

Urbanization and climate change present increasing challenges to outdoor human thermal comfort, particularly in university campuses where academic, social, and recreational activities converge. This study assesses microclimatic risk factors along the main avenue of the NOVA FCT campus by analyzing outdoor human thermal comfort using the physiologically equivalent temperature (PET) and modified PET (mPET) indices. Field measurements of air temperature, humidity, wind velocity, and radiation were conducted at multiple Points Of Interest (POIs) to evaluate thermal stress levels and identify critical zones of discomfort. Results indicate significant spatial and temporal variations in thermal stress, with sun-exposed areas (G2) experiencing PET values exceeding 50 °C, during peak summer hours, while shaded locations (G1) showed substantial thermal relief (PET reductions up to 27 °C between G1 and G2 POIs). Wind velocity and urban morphology played crucial roles in modulating microclimatic conditions. Wind velocity above 2.0 m/s was associated with perceptible thermal relief (3–8 °C PET/mPET reduction), especially in narrow, shaded passages. Significant spatial variability was observed, linked to differences in urban morphology, surface materials, and vegetation coverage. This research provides actionable insights for urban planners and campus administrators, contributing to the development of more sustainable and thermally comfortable outdoor environments in educational settings. Full article

This study investigates how visual environmental factors influence wayfinding behavior in underground spaces, with a particular focus on cultural differences between Korean and Chinese college students. A virtual reality (VR) environment was developed using Unity3D to simulate an underground space, incorporating five key visual variables: passage width, brightness, color temperature (warm vs. cool), the presence or absence of obstacles, and the configuration of sign systems. Participants were divided into two groups—Korean (Group K) and Chinese (Group C)—and engaged in a VR-based wayfinding experiment followed by an emotional vocabulary evaluation. The results indicate significant cultural differences in spatial perception and navigation preferences. Chinese participants preferred narrower, brighter, and cool-colored passages, associating them with an improved sense of direction, lower stress, and enhanced attention. In contrast, Korean participants favored wider, darker, and warm-colored passages, valuing accessibility, stability, and distance perception. Both groups showed a strong preference for environments with floor signage and combined sign systems, though Korean participants were more tolerant of obstacles. These findings provide practical insights for designing more inclusive and navigable underground public spaces across different cultural contexts. Full article

Transcatheter aortic valve replacement (TAVR) has become a well-established treatment for severe aortic stenosis across all levels of surgical risk. While transfemoral access remains the default approach, complications arising from vascular access—especially in patients with peripheral artery disease (PAD)—pose significant challenges. Hostile vascular access, characterized by narrow vessel diameters, severe calcification, and tortuosity, complicates the procedure and necessitates alternative strategies. Recent advancements, such as intravascular lithotripsy (IVL), have shown promise in managing severely calcified arteries, improving the feasibility of transfemoral TAVR in patients previously considered ineligible. IVL uses pulsatile sonic waves to fragment arterial calcifications, enhancing vessel compliance and facilitating safe device delivery. Studies have demonstrated that IVL-assisted TAVR improves procedural success and reduces complications in patients with PAD. Additionally, orbital atherectomy, an adjunctive therapy targeting both concentric and eccentric calcifications, may complement the management of complex arterial calcification. The Hostile and passage–puncture scores offer valuable risk stratification tools for predicting vascular complications, aiding in better access site selection. Post-procedural echocardiography, particularly femoral artery sonography, may also play a role in detecting vascular complications early, enabling timely intervention. Finally, alternative access sites are increasingly being explored, with emerging data helping to guide the final access site decision. As TAVR continues to expand into lower risk populations, optimizing vascular access strategies remains essential to improving procedural outcomes. This review highlights the importance of preoperative imaging, endovascular techniques, and post-procedural monitoring in overcoming vascular challenges and ensuring successful TAVR outcomes. Full article

The spatial navigation of filamentous fungi was compared for three species, namely Pycnoporus cinnabarinus, Neurospora crassa wild type and ro-1 mutant, and Armillaria mellea, in microfluidic structures. The analysis of the navigation of these filamentous fungi in open and especially confining environments suggests that they perform space exploration using a hierarchical, three-layered system of information processing. The output of the space navigation of a single hypha is the result of coordination and competition between three programs with their corresponding subroutines: (i) the sensing of narrow passages (remote- or contact-based); (ii) directional memory; and (iii) branching (collision-induced or stochastic). One information-processing level up, the spatial distribution of multiple, closely collocated hyphae is the result of a combination of (i) negative autotropism and (ii) cytoplasm reallocation between closely related branches (with anastomosis as an alternative subroutine to increase robustness). Finally, the mycelium is the result of the sum of quasi-autonomous sub-populations of hyphae performing distribution in space in parallel based on the different spatial conditions and constraints found locally. The efficiency of space exploration by filamentous fungi appears to be the result of the synergy of various biological algorithms integrated into a hierarchical architecture of information processing, balancing complexity with specialization. Full article

This paper addresses the path planning problem in high-dimensional complex environments and proposes an improved FRRT*-Connect algorithm to enhance the efficiency, precision, and robustness of path generation. The algorithm first introduces a goal-directed attractive force control mechanism, integrating artificial potential field methods to guide the tree expansion more effectively toward the goal, thereby reducing redundant sampling and significantly improving convergence speed. Secondly, an adaptive step-size strategy is proposed, dynamically adjusting the tree expansion step size based on the complexity of the environment, which enhances the algorithm’s adaptability in narrow passages and complex topological structures, effectively avoiding local minima. The results show that, compared to the RRT*-Connect algorithm, the proposed method exhibits significant advantages in path quality, convergence efficiency, and success rate: the average path length is reduced by 19.7%, convergence speed is improved by 58.4%, and the success rate reaches 98% in narrow passage scenarios. These improvements effectively overcome the issues of path redundancy, slow convergence, and local minima inherent in traditional RRT-based algorithms, demonstrating superior performance in challenging scenarios with complex obstacles and narrow passages. Full article

Based on soft body structure and unique gait of bending and stretching, Soft Bionic Inchworm Robots (SBIRs) are used in pipeline inspection and terrain exploration. Many existing SBIRs rely on complex production mechanisms and are cable-driven, which hinders rapid production and smooth movement through complex environments, respectively. To address these challenges, this paper introduces a 3D-printed SBIR, featuring a 3D-printed body actuated by magnetic forces. We introduce the design and production process of the 3D-SBIR and analyze its motion gait. Subsequently, the material composition model and bending deformation model of the robot are developed based on the theory of hyper-elastic materials. The accuracy of the model is validated using simulation analysis and experimental testing of the robot. Meanwhile, we carry out a magnetic simulation analysis and discuss the factors influencing the size of the magnetic force. Finally, a series of experiments are conducted to prove the excellent locomotion capability of the robot. The 3D-SBIR demonstrates remarkable flexibility and multimodal movement capabilities. It can navigate through narrow curved passages with ease, passively overcome obstacles, climb steps up to 0.8 times its body height, and perform a seamless transition while moving across a horizontal plane onto a vertical plane. The 3D-SBIR proposed in this paper is characterized by rapid production, cable-free actuation, and multimodal motion capabilities, making it well suited for moving in unstructured environments. Full article

Street-type spaces, characterized by their relative closedness and propensity for human congregation, inherently carry potential safety evacuation risks. In order to study the influence of slopes on the evacuation efficiency of pedestrians in street-type public spaces under the state of passenger flow surge during holidays, this study systematically analyzes the changing rules and behavioral characteristics of pedestrian evacuation in downhill movement through a three-phase analysis of the risk of crowd gathering in urban street-type spaces (before, during, and after) and evacuation simulation experiments combining variables such as slope, street width, obstacle layout, disability type, and group movement. The findings indicate that, in the structural design of street-type spaces, slopes of more than 4° should be minimized to maintain the smooth flow of pedestrians. Areas in streets with widths narrower than 2 m are high-risk zones for crowd gathering and should be better supervised. The number and location of obstacles should be reasonably arranged under the condition of satisfying the safety of pedestrians’ passage. The differences in the ability of evacuees should be taken into account to improve evacuation system deficiencies and ensure that everyone can evacuate safely. Ultimately, we propose a preventive mechanism for the safe evacuation of urban street-type public spaces to reduce the risk of crowd gathering and safeguard pedestrians. This study provides a theoretical framework for understanding the dynamics of pedestrian evacuation in inclined street-type spaces, thereby guiding urban planners and public safety managers to enhance the design and management of such spaces. Full article

Background: The nasal septal swell body (NSB) is a thickened area of the nasal septum with erectile tissues, located above the nasal floor. We hypothesized that the presence of the NSB in this space exerts favorable effects to generate laminar nasal airflow by developing its morphology as adjusted to nasal septal deviation (NSD). Patients and Methods: We objectively measured the NSB morphology in 152 patients by computed tomography (CT) and assessed its relationship with the width of the inferior turbinate (IT), the severity of NSD, and the patency of the nasal airflow passage (NAP). Results: In the patients with moderate or severe NSD, the mean widths of the NSB, IT, and NAP were significantly narrower at the convex side compared to the paired concave side, with the degree being more prominent in the severe-NSD group. A positive correlation was observed between the degree of the NSD angles and the difference in the widths of the NSB (r = 0.805) and IT (r = 0.609). Conclusions: These results imply novel roles of the NSB in the maintenance of physiological nasal airflow to generate a laminar airflow from the nostrils toward the middle nasal meatus at a constant rate. Full article

In this study, an online path planning strategy capable of traversing narrow passages is proposed for an autonomous underwater vehicle equipped only with forward-looking sonar in unknown environments. First, to establish the environment model, the sonar fan-shaped detection area is subdivided into multiple sectorial grids. Then, a comprehensive cost function combining safety, smoothness, and cost is utilized to generate the optimal heading. Furthermore, to safely pass through narrow passages, a sequence of subgoals for polynomial trajectory planning are determined on the perpendicular bisector ahead of the central line. The simulation results demonstrate the effectiveness of the proposed strategy, which determines the optimal heading through fan-shaped grid costs and generates a safe and smooth path. The AUV can achieve more safety navigating in obstructed areas and narrow passages. Full article

This article explores the variable properties of auditory image analysis during the perception of musical works, which are influenced by the specific elements to which the listener directs their attention. Traditional analyses of musical compositions typically involve brief comparisons with auditory phenomena described in scientific studies, such as those by A.S. Bregman. However, these analyses are often limited, offering only a narrow perspective on the works. In contrast, the approach presented in this article extends the theories and experiments developed by Bregman and others, providing a more comprehensive understanding of entire compositions or selected sections rather than focusing solely on isolated passages. This broader framework enhances auditory image analysis and serves as a foundation for further research. The expanded analysis integrates within music theory, enabling a deeper exploration of musical structures, particularly in the context of perceiving multilayered music where multiple sound sources may share similar acoustic features. The author illustrates how acoustic and perceptual factors contribute to complex mental representations through graphic and musical examples. To substantiate the claims, classical works by composers such as F. Chopin, A. Guilmant, and J.S. Bach are analysed, further highlighting the variable properties of auditory image analysis. Full article

A recurrent challenge on cycle paths are edge cracks, which affect the traffic safety and accessibility of cyclists and produce high maintenance costs. Being both structurally thinner and narrower structures than roads, the cycle paths are extra prone to this problem. A few passages of heavy vehicles in unfavourable conditions might be enough to break the edge. The load-bearing capacity of eight municipal cycle paths in Linköping, Sweden, were assessed by falling weight deflectometer (FWD) and light falling weight deflectometer (LWD) measurements during a year-long cycle. A set of alternative Deflection Bowl Parameters (DBPs), better adapted to the structural design of cycle paths, were suggested and evaluated. The results of the FWD measurements showed that these suggested DBPs are a promising approach to evaluate the load-bearing capacity of cycle paths. From the results of the LWD measurements, it was found that the load-bearing capacity varies considerably with lateral position. The conclusion is that it might be more fruitful to measure the load-bearing capacity by LWD close to the edge, rather than the traditional approach of FWD measurements along the centre line of the cycle path. Full article