Head Design Research Articles

On a river-barge numerical strength analysis in head design wave loads

On a river-barge numerical strength analysis in head design wave loads

AwareTrack: Object awareness for visual tracking via templates interaction

Current popular trackers, whether based on the Siamese network or Transformer, have focused their main work on relation modeling between the template and the search area, and on the design of the tracking head, neglecting the fundamental element of tracking, the template. Templates are often mixed with too much background information, which can interfere with the extraction of template features. To address the above issue, a template object-aware tracker (AwareTrack) is proposed. Through the information interaction between multiple templates, the attention of the templates can be truly focused on the object itself, and the background interference can be suppressed. To ensure that the foreground objects of the templates have the same appearance to the greatest extent, the concept of awareness templates is proposed, which consists of two close frames. In addition, an awareness templates sampling method based on similarity discrimination via Siamese network is also proposed, which adaptively determines the interval between two awareness templates, ensure the maximization of background differences in the awareness templates. Meanwhile, online updates to the awareness templates ensure that our tracker has access to the most recent features of the foreground object. Our AwareTrack achieves state-of-the-art performance on multiple benchmarks, particularly on the one-shot tracking benchmark GOT-10k, achieving the AO of 78.1%, which is a 4.4% improvement over OSTrack-384.

A novel green CeO2 polishing slurry and its chemical mechanical action mechanism for achieving atomic-level smoothing of fused silica glass surfaces

Pitch-based tools are integral to computer-controlled optical surfacing (CCOS) for polishing fused silica but face limitations such as low material removal rates (MRR) and challenges in achieving atomic-level smoothing while ensuring environmental sustainability. While chemical mechanical polishing (CMP) excels in processing planar surfaces, it struggles with complex freeform geometries. CCOS addresses this gap with specialized tool head designs that enable precise machining of intricate surfaces. This study introduces an eco-friendly CeO2-based polishing slurry suited for CCOS with pitch tools. By incorporating green reagents, such as polyethylene glycol (PEG) and ethylene glycol (EG), and minimizing harmful chemical usage, the slurry achieves significant breakthroughs in performance. Experimental results reveal a surface roughness (Sa) of 0.075nm, meeting atomic-level smoothing standards, alongside an MRR of 40.5 μm /h, marking substantial improvements over traditional methods. Physicochemical analyses of the CeO2 abrasives, including particle size, morphology, and Ce element content, revealed that abrasives with sharp edges and high Ce content are key factors for obtaining high surface quality and MRR. Molecular dynamics (MD) simulations highlight the synergistic effects of the components, optimizing chemical-mechanical interactions to enhance surface quality. These findings demonstrate the potential of green polishing technologies in advancing the precision machining of fused silica, particularly for complex geometries. The study provides a sustainable and high-performance solution for achieving atomic-level smoothing, paving the way for broader applications in precision optics.

Not the Silver Bullet: Uncovering the Unexpected Limited Impacts of Silver-Containing Showerheads on the Drinking Water Microbiome.

The incidence of waterborne disease outbreaks in the United States attributed to drinking water-associated pathogens that can cause infections in the immunocompromised DWPIs (e.g., Legionella pneumophila, nontuberculous mycobacteria (NTM), and Pseudomonas aeruginosa, among others) appears to be increasing. An emerging technology adopted to reduce DWPIs are point-of-use devices, such as showerheads that contain silver, a known antimicrobial material. In this study, we evaluate the effect of silver-containing showerheads on DWPI density and the broader microbiome in shower water under real-use conditions in a full-scale shower system, considering three different silver-modified showerhead designs: (i) silver mesh within the showerhead, (ii) silver-coated copper mesh in the head and hose, and (iii) silver-embedded polymer composite compared to conventional plastic and metal showerheads. We found no significant difference in targeted DWPI transcriptional activity in collected water across silver and nonsilver shower head designs. Yet, the presence of silver and how it was incorporated in the showerhead influenced the metal concentrations, microbial rare taxa, and microbiome functionality. Microbial dynamics were also influenced by the showerhead age (i.e., time after installation). The results of this study provide valuable information for consumers and building managers to consider when choosing a showerhead meant to reduce microorganisms in shower water.

Research on the rock cutting performance and feasibility verification of small-scale rotary cutting test for disc cutter

Small-scale rock cutting tests serve as a simple approach to evaluate the performance of tunnel boring machines (TBMs), but the feasibility of this method requires further investigation. Herein, a small-scale rotary cutting machine is developed to conduct rock cutting tests, and the cutting performance is investigated. The results indicate that similar cutting performance can be achieved through both small-scale and full-scale tests. The critical penetration depth for effective rock cutting by the cutter is 0.5 mm, below which the cutter grinds against the rock. The optimal ratio of cutting spacing to penetration depth obtained in small-scale tests is 4.47. A result within the empirical range can be achieved by multiplying the optimal small-scale cutting parameters with the scale coefficient, demonstrating the feasibility of using small-scale tests to guide the design of cutter heads. Based on the test result, the scale prediction model is constructed to predict the full-scale cutting force. The predictive capability of the proposed model and CSM model is validated using 72 sets of full-scale test data involving the same types of rock, and the predictions of the proposed model are closer to the test data.

IMPROVEMENT OF THE HOMOGENIZER HEAD DESIGN

Summary. An analysis of the equipment used for the homogenization of milk raw materials was carried out. Technologies for obtaining homogenized milk are considered. Disadvantages of existing technological processes have been identified. The areas of improvement of homogenization processes are defined and the need for the development of equipment for their implementation is substantiated. The research methods of the homogenization process are substantiated, a description of the studied raw materials is given, and the design of the homogenizer head is proposed. The influence of the geometric parameters of the modernized homogenizer head on the efficiency of the homogenization process was determined, and the optimal parameters were determined experimentally. As a result of the conducted research, it can be concluded that the homogenization process is very important for the production of pharmaceutical emulsions. The calculation and modeling of the homogenizing head of the valve homogenizer was carried out. In order to carry out two-stage homogenization, it was proposed to modernize the homogenizing head. the previous design is inferior to the modernized one in terms of homogenization of food liquids.

A comparative analysis of the aerodynamic performance of supersonic missiles with conical and ogive nose shapes

This paper presents a numerical study conducted to analyze the aerodynamic performance of supersonic missiles consisting of a cylindrical body and four flat-plate rear fins arranged uniformly, equipped with conical and ogive heads. Computational Fluid Dynamics (CFD) simulations were performed using the ANSYS Fluent 17.1 solver, along with the Gambit grid generation software. The objective was to compare the aerodynamic characteristics of these two head designs in terms of drag, lift, and stability at supersonic speeds. Various flow parameters, including Mach number and angle of attack, were investigated to comprehensively assess the performance of the missile configurations. The results indicate clear differences in the aerodynamic behavior of conical and ogive heads. Specifically, there was a 2–11 percent increase in the lift coefficient of the conical heads compared to the ogive heads, and an increase in the drag coefficient of both conical and ogive heads.

A comprehensive design for biomimetic behavior of robotic head

In robotics and human-robot interaction, the ability to express emotions and respond accurately to human emotions is essential. An important aspect of this ability involves controlling the robot’s facial actuators in a way that resonates with human emotions. This study systematically presented the construction of a robot head based on the theoretical foundation of human sustainability. Facial landmarks are extracted for various purposes, such as to determine anthropometric metrics for robot head design, a comprehensive design for the robotic head is proposed in this study including anthropometric measurements used as a theoretical basis for the design, the calculations, and design, control system, electricity, and robot skin are presented. The robotic head with 24 degrees of freedom (DoF) aims to express all human emotions, signals are fed back from strain gauge sensors and cameras to calibrate the response of the robot’s prosthetic muscles. Strain gauge sensors are set up at locations with large deformations to double-check the functioning of prosthetic muscles. The two experiments are set up to evaluate the completeness of emotions, the results showed that both experiments achieved 93.88% and 91.85% respectively.

A Biomechanical Comparative Analysis of Abutment Screw Head Designs on Preload Stability Under Oblique Compressive Forces: An In Vitro Pilot Study.

The purpose of this study was to examine the impact of abutment screw head sizes on preload stability when secured to a standard external hex implant under oblique compressive forces. Fifteen metal crowns were divided into 3 equal groups. The first group had 5 angulated cemented crowns connected to a 3-mm-tall straight hexagonal abutment with an external hex abutment screw. The second and third groups each had 5 straight cemented crowns attached to a tapered abutment with flat-slotted and internal hex abutment screws, respectively. Samples were subjected to a static cyclic load until failure. Kruskal-Wallis H, Dunn, and one-way analysis of variance with Tukey honestly significant difference tests were performed. Cemented straight crowns supported by an angled abutment connected to implants with flat-slotted and internal hex abutment screw heads failed at an average of 4.24 × 106 cycles ± 3.31 SD and 12.67 × 106 cycles ± 5.47 SD, respectively. Cemented angled crowns supported by a straight abutment connected to identical implants with an external hex abutment screw survived 18.02 × 106 cycles ± 4.49 SD. The periotest value rate of change increased at a higher rate in crowns supported by angled abutments compared with straight abutments (p < .05). No cement failure was observed. Under the experimental conditions, larger abutment screw head sizes demonstrated greater stability of the abutment-abutment screw joint interface. Based on the in vitro findings, no cement failure was observed between the cemented crown and abutment connection. Future research with standardized comparative setups and larger sample sizes is needed.

Transoral Laser or Robotic Surgery Outcomes for Oropharyngeal Carcinoma

Transoral robotic surgery (TORS) or transoral laser microsurgery (TLM) offer excellent oncological outcomes for oropharyngeal squamous cell carcinoma caused by human papillomavirus (HPV) infection. TORS may offer greater margin clearance around tumors than TLM. To determine whether the differing energy sources used and surgical technique of TORS or TLM is associated with postoperative early swallowing function, feeding tube use, and specific factors related to quality of life. This prespecified cohort study was performed within the Postoperative Adjuvant Treatment for HPV-Positive Tumours (PATHOS) randomized clinical trial at 40 centers in the UK, Germany, France, the US, and Australia between November 1, 2015, and August 31, 2023. PATHOS trial participants with HPV-positive oropharyngeal carcinoma of stages T1 to T3 and N0 to N2b M0 (TNM7) who underwent TLM or TORS were eligible. Of 989 consecutively recruited patients on the PATHOS trial, 508 were eligible for this substudy. The exposure of interest was TORS or TLM. Preplanned outcome measures included nasogastric tube insertion rates within 4 weeks after surgery, length of in-hospital stay following surgery, specific scales from the MD Anderson Dysphagia Inventory (MDADI), 35-item European Organization for Research and Treatment of Cancer Head and Neck Questionnaire (H&N35), and 30-item Quality of Life Questionnaire (QLQ C30), water swallow test results, and videofluoroscopy scores. Of the 508 patients included in the analysis (390 [76.8%] male; median age, 58.3 [IQR, 52.8-63.6] years), 195 had TLM and 313 had TORS. Nasogastric tube insertion rates were higher after TORS than TLM (85 of 189 [45.0%] vs 10 of 126 [7.9%]; adjusted odds ratio [OR], 4.41 [95% CI, 1.01-19.32]). Mean scores favored TLM with small effect sizes in all MDADI domains and the H&N35 swallowing item at 4 weeks after surgery; between-group difference for the MDADI composite score was -4.89 (95% CI, -8.27 to -1.50); for the MDADI physical functioning score, -6.37 (95% CI, -10.15 to -2.59); for the MDADI global score, -10.02 (95% CI, -16.50 to -3.54); and for H&N35 swallowing score, 7.24 (95% CI, 2.17-12.30). No other measures showed evidence of clinically meaningful differences. In this cohort study, functional outcomes were moderately less impaired 4 weeks following TLM compared with TORS. Once the longer-term outcomes for these patients are known, these findings could aid the design and use of future head and neck-specific surgical robots. ClinicalTrials.gov Identifier: NCT02215265.

Car detection algorithm in urban based on YOLOv5

Car detection is essential to promote the development of intelligent technologies such as autonomous driving and car forward collision warning. To deal with low detection accuracy, poor real-time performance and robustness of existing object detection algorithms, a YOLOv5-based car detection algorithm is used. The advanced structure design of Backbone, Neck and Head in YOLOv5 demonstrates powerful feature extraction and multi-scale object detection capabilities. The detection results reveal that the algorithm is able to quickly recognize cars in images in different urban scenes, and the detection accuracy can reach more than 95%, which can satisfy the application demands for real-time car detection.

Study on the dynamic characteristics of the head cover-bolts-stay ring of a variable-speed pump-turbine

Abstract The design and operation of variable-speed pump-turbine units is more difficult than that of conventional units due to their adjustable speed, frequent start stop, and forward and reverse operation. Due to the development of variable-speed pump-turbines towards variable-speed, high head, and large capacity, the vibration instability caused by frequent switching between turbine and pump operating conditions is more prominent. The study on the dynamic characteristics of the head cover-bolts-stay ring system is an important guarantee for the long-term safe and stable operation of the units. This article uses the finite element method to conduct modal analysis on the head cover-bolts-stay ring system of a variable-speed pump-turbine. The natural frequency and mode shape are analyzed, and resonance analysis is carried out in combination with the dynamic and static interference characteristics of the variable-speed unit. The research results show that the dynamic and static interference frequency of the unit during the variable-speed process may be close to the natural frequency of the head cover-bolts-stay ring system, which needs to be paid attention to during operation. The results and findings in this article provide theory and practical basis for the research and design of high head, large capacity, and variable-speed pump-turbine units.

Design of a new scintillator-based fast ion loss detector on the HL-2A tokamak

A new scintillator-based fast ion loss detector (FILD) has been devised for the HL-2A tokamak, with the objective of discerning the temporal evolution of energy and pitch angle among lost fast ions. A code named FILD Simulation (FSC) has been developed to assist in the design of the detector head and the interpretation of experimental data. By optimising the geometric design, the resolutions of energy and pitch angle are optimised to 5 keV and 3°, respectively. A branched imaging fiber bundle is used to relay the fluorescence image on the scintillator to two distinct instruments. One of these is a high-speed camera, while the other is a silicon photomultiplier tube (SiPM) array with a sampling rate of up to 1 MSamples/s. This configuration enables the attainment of superior temporal and spatial resolution, as well as high photon sensitivity.

UAV Vehicle Detection System Based on YOLOv8

Abstract To utilize the drone vehicle detection technology to observe the road traffic conditions in real-time, thereby improving the operational effectiveness and safety of the traffic system, this paper adopts a vehicle target detection algorithm based on YOLOv8. YOLOv8 is the latest iteration developed by Ultralytics, which has further improvements and enhancements compared to YOLOv5. In the backbone network, YOLOv8 employs a C2f structure with richer gradient flow, boosting feature selection capabilities, and enhancing target detection performance and accuracy; In the detection head, YOLOv8 utilizes a Decoupled Head design and uses an improved Anchor-Free method to reduce computational complexity while improving detection efficiency; In terms of loss function, YOLOv8 utilizes the The Task-Aligned Assigner positive sample allocation strategy, and adds the Distribution Focal Loss to improve the model’s generalization ability. This paper divides the vehicles data set into 5 types, trains it using a pre-training model, and optimizes the network parameters through multiple iterations to achieve better detection performance. The experimental results indicate that YOLOv8 reaches the mAP of over 97% on the experimental data set, which is an improvement of approximately 8% compared to YOLOv5, and achieves a good detection performance, and is highly practical.

Laboratory-Scale Limestone Rock Linear Cutting Tests with a Conical Pick: Predicting Optimal Cutting Conditions from Tool Forces

This study introduces a simplified method for predicting the optimal cutting conditions to maximize excavation efficiency based on tool forces. A laboratory-scale linear rock-cutting test was conducted using a conical pick on Finike limestone. The tool forces and their ratios were analyzed in relation to cutting parameters such as penetration depth and spacing. While the cutting force (FC) and normal force (FN) increased with the penetration depth and spacing, this relationship could not predict the optimal cutting conditions. The ratio of the mean normal force to the mean cutting force (FNm/FCm) increased with the penetration depth and the ratio of spacing to penetration depth (s/d). However, even while including this relationship, predicting optimal cutting conditions remained challenging. The ratio of the peak cutting force to the mean cutting force (FCp/FCm) reached a maximum value at a specific s/d, which is similar to the relationship between the specific energy (SE) and s/d. The optimal s/d obtained through the SE methodology was found to be between 3 and 5, and FCp/FCm reached a maximum at s/d. The error between the optimal s/d and the s/d in which FCp/FCm was maximized was less than 5%. Therefore, it was confirmed that the optimal cutting conditions could be predicted through the relationship between FCp/FCm and s/d. Additionally, by using the results from previous studies, the optimal cutting conditions obtained from the SE methodology and the proposed methodology were found to agree within a margin of error of 20%. The proposed methodology can be beneficial for the design of cutter heads and the operation of excavation machines.

A versatile 5-axis melt electrowriting platform for unprecedented design freedom of 3D fibrous scaffolds

Melt electrowriting (MEW) is an electrohydrodynamic additive manufacturing technology for the fabrication of precise microfiber scaffold architectures but is so far restricted to printing onto simple collector geometries and, therefore, constrained in design freedom. This is due to current limitations in print head designs, kinematic systems, and software to generate motion commands. We address these aspects by upgrading a low-cost 5-axis kinematic system and complete it with a custom-designed print head and a collector fabrication workflow to enable collision-free MEW onto arbitrarily shaped multicurvature 3D geometries. A universal graphical approach enables generation of Gcodes customized to the 5-axis MEW requirements. The print head is validated by producing polycaprolactone fibers with diameters ranging from 5.6 ± 1.7 µm to 50.7 ± 5.5 µm and by writing both linear and non-linear fiber patterns onto collectors featuring concave and convex surfaces. Stable printing conditions are achieved by continuously reorienting the print head and collector surface perpendicular to each other at a constant working distance. Ultimately, we demonstrate the system’s potential in shaping anatomically relevant scaffold geometries by stacking microfibers onto collectors resembling a trileaflet valve and a bifurcating vessel. This multi-axis MEW platform unlocks exciting avenues towards unprecedented design freedom for MEW scaffolds.

Design and Testing of a 2-DOF Adaptive Profiling Header for Forage Harvesters

The existing forage harvester header cannot automatically adjust the height and inclination during operation, resulting in uneven stubble height of forage, which, in turn, affects the efficiency of harvesting and the quality of forage regeneration. To address this issue, this study conducted the design and experimentation of a 2-degrees-of-freedom (DOF) profiling header. Firstly, this study designed an adaptive profiling header with 2-DOF adjustment, which was realized by the height adjustment mechanism and the tilt angle adjustment mechanism. The relationship model between the profiling device and the attitude of the header was established so that the header can acquire ground undulation in real time through the angle sensor of the profiling device. In order to verify the rationality of the header design, a co-simulation model of ADAMS and MATLAB/Simulink was built, and the header attitude control system was designed based on the fuzzy PID algorithm. The co-simulation results show that the header height (H) is always kept around 150 mm during the forwarding process of the harvester, with a maximum error of 5.8 mm, and the average relative error (REH) and root mean square error (RMSEH) were 1.4% and 2.6 mm, respectively, and the maximum error of the tilt angle (γ) of the header is 0.53° and the RMSEγ is 0.22°, which indicates that the header profiling mechanism can accurately reflect the undulation of the terrain and the header attitude control system has good robustness. Finally, the test platform was built and tested in a grassland. The test results show that the average height of the header is 149.8 mm, the maximum error is 7.5 mm, and the REH and RMSEH are 3.4% and 5.3 mm, respectively. The average error of the header inclination is 0.34°, and the maximum error is 0.57°. The test results indicate that the header can realize the adaptive adjustment of height and inclination, and the control system has high precision, stability and reliability, meeting the demand of automatic regulation of header attitude of a forage harvester.

Numerical Investigation of Flow Distribution in PEMFC and Pemwe Stacks Considering Two-Phase Flow in the Stack Headers

PEM fuel cell (PEMFC) and PEM water electrolyzer (PEMWE) stacks are assembled by connecting a series of unit cells. The stack headers are conduits formed by the ports of these unit cells; see Fig. 1(a). The flow field in the headers affects the flow uniformity of the stack, which significantly impacts the stack’s performance and lifespan. This study aims to investigate the fluid flows in the stack headers of PEMFC and PEMWE. A specific objective of this study is to understand how two-phase flow (liquid water and gases) in the headers would impact the flow distribution inside the stacks.The present study investigates the flow inside a stack by two-dimensional (2D) and three-dimensional (3D) models, as shown in Figure 1(b) and (c) respectively. The 3D model was constructed with an inlet header and an outlet header with flow resistors in between to represent the unit cells.1,2 CFD simulations using ANSYS Fluent were performed over a 100-cell PEMFC stack based on the k-ε RNG turbulence model. The two-dimensional 100-cell PEMFC stack model was built with COMSOL Multiphysics and considers the diffusion and transport, proton and electron conduction, electrochemical reactions on the catalytic layer, and heat transfer in the unit cells. The flow distribution obtained from the 3D model was used as the boundary conditions for the 2D model to calculate the effects of flow distribution on the overall performance of the stack. It should be pointed out that in the 3D models of PEMFC and PEMWE headers, simulations using the volume of fluid (VOF) model to track the liquid water droplets in a PEMFC and bubbles in a PEMWE were carried out to gain insights into the impact of two-phase flow on stack header flow sharing.The simulation results show the existence of unstable and highly transient turbulence within the PEMFC outlet header, as seen in Figs. 1(d) and 1(e). Jet flows from individual cells cause vortices inside the header, reducing the effective flow area. Liquid water accumulates on the inner wall of the header and is swept out by the cross-flow. In the dead-end region, liquid water undergoes helical motion under the influence of vortices, resulting in a longer residence time in the header and making it less prone to be expelled. This study parametrically investigated the effects of header size and air stoichiometry. As the cross-sectional area of the inlet header decreases from A=1,225 mm2 to A=857.5 mm2, the coefficient of mass flow variation within the stack increases, indicating a decrease in the uniformity of flow distribution inside the stack, as shown in Fig. 1(f). The air stoichiometry also affects the flow distribution inside the stack; as the air stoichiometry λ decreases from 2.2 to 1.4, the uniformity of gas distribution in the stack deteriorates significantly.The methodology used in the present study provides a reference for the parameter design and operating conditions of PEMFC and PEMWE stacks. It helps to gain insights into the optimization of stack header design and energy management.

Cryogen-free modular scanning tunneling microscope operating at 4-K in high magnetic field on a compact ultra-high vacuum platform.

One of the daunting challenges in modern low temperature scanning tunneling microscopy (STM) is the difficulty of combining atomic resolution with cryogen-free cooling. Further functionality needs, such as ultra-high vacuum (UHV), high magnetic field (HF), and compatibility with μm-sized samples, pose additional challenges to an already ambitious build. We present the design, construction, and performance of a cryogen-free, UHV, low temperature, and high magnetic field system for modular STM operation. An internal vibration isolator reduces vibrations in this system, allowing for atomic resolution STM imaging while maintaining a low base temperature of ∼4K and magnetic fields up to 9T. Samples and tips can be conditioned in situ utilizing a heating stage, an ion sputtering gun, an e-beam evaporator, a tip treater, and sample exfoliation. In situ sample and tip exchange and alignment are performed in a connected UHV room temperature stage with optical access. Multisite operation without breaking vacuum is enabled by a unique quick-connect STM head design. A novel low-profile vertical transfer mechanism permits transferring the STM between room temperature and the low temperature cryostat.

Thermal Performance Improvement of Cross-Flow Double-Layered Microchannel Heat Sinks through Proper Header Design

Thermal Performance Improvement of Cross-Flow Double-Layered Microchannel Heat Sinks through Proper Header Design