Hard Contact Research Articles

Axial behavior variation of 72-story concrete-filled steel tubes with different joint connections due to interface debonding considering long-term deformation of concrete core

Long-term concrete deformation including shrinkage and creep occurring seriously threats the longevity, safety and serviceability of concrete-filled steel tube (CFST) structures. In this study, numerical simulation on the variation of axial behavior of 72-story CFST structures with different joint connection details due to interface debonding considering shrinkage and creep of concrete core is carried out. Three connection details including connections with inner horizonal diaphragms only, two-direction through-beams only, and inner horizontal diaphragms combined with two-direction through-beam, are considered, respectively. Vertical loading from floors is treated as centralized vertical force applied on steel tube directly. The shrinkage of concrete core is simulated by decreasing concrete temperature. A cohesive constitutive law and a Coulomb friction model are employed to describe the interface behavior in tangential direction before and after debonding, respectively. The interaction between concrete core and steel tube in normal direction is treated as a hard contact. The concrete plastic-damage (CPD) constitutive model is used for concrete core and a plastic constitutive law is employed for the steel tube. The initiation of the interface debonding between steel tube, H-shaped steel beam flanges, inner diaphragms and concrete, the variation of the force transfer path, stress redistribution, steel tube yielding and the final failure are described in detail. Results show that the axial load-carrying capacity of each CFST structure has a decrease of 26–28 % when compared with that determined by the current design code where the confinement effect is considered, and a decrease of 9–10 % when compared with that determined by the current design code where the confinement effect of steel tube is not considered. Moreover, the axial stiffness decreases to 76–78 % of their theoretical values when debonding is not considered. Numerical results show that the interface debonding negatively affects the long-term axial load-carrying capacity and stiffness obviously, which has not been considered in current design codes. Some comments on the design of CFST members are proposed based on the numerical simulation results.

Contact-implicit Model Predictive Control: Controlling diverse quadruped motions without pre-planned contact modes or trajectories

This paper presents a contact-implicit model predictive control (MPC) framework for the real-time discovery of multi-contact motions, without predefined contact mode sequences or foothold positions. This approach utilizes the contact-implicit differential dynamic programming (DDP) framework, merging the hard contact model with a linear complementarity constraint. We propose the analytical gradient of the contact impulse based on relaxed complementarity constraints to further the exploration of a variety of contact modes. By leveraging a hard contact model-based simulation and computation of search direction through a smooth gradient, our methodology identifies dynamically feasible state trajectories, control inputs, and contact forces while simultaneously unveiling new contact mode sequences. However, the broadened scope of contact modes does not always ensure real-world applicability. Recognizing this, we implemented differentiable cost terms to guide foot trajectories and make gait patterns. Furthermore, to address the challenge of unstable initial roll-outs in an MPC setting, we employ the multiple shooting variant of DDP. The efficacy of the proposed framework is validated through simulations and real-world demonstrations using a 45 kg HOUND quadruped robot, performing various tasks in simulation and showcasing actual experiments involving a forward trot and a front-leg rearing motion.

A semi-analytical approach for dynamic responses of monopile-supported offshore wind turbines subjected to accidental loads

Offshore wind energy is leading the way in sustainable energy generation. Offshore wind turbines (OWTs) need to be designed to withstand extreme or accidental loads in Ultimate Limit States (ULS) and Accidental Limit States (ALS), whereby high order eigenmodes may become significant. This paper introduces a semi-analytical approach for efficient and reliable analysis of the dynamic responses of monopile-supported OWTs subjected to accidental loads. A Rayleigh-Ritz solution is initially adopted to determine the high-order natural frequencies and eigenmodes of monopile OWTs, explicitly considering tapered towers and soil-pile interactions. Dynamic responses of OWTs are then calculated depending on the interaction schemes between accidental loads and the structures, e.g. soft contact loads (e.g. slamming, wind) and hard contact loads (e.g. ship collisions, ice impact). For soft contact loading conditions, the loads are considered independent of turbine responses, and the transient dynamic response is computed using the classical modal superposition method. While for hard contact loading conditions, the load actions depend on the contact stiffnesses and responses of the interacting bodies. A numerical contact algorithm is thus developed, and numerical iterations are performed to ensure convergence. The proposed approach is applied to the DTU 10 MW monopile-supported OWT subjected to extreme water slamming and ship collisions, respectively as example applications of soft and hard contact scenarios. The results are verified against nonlinear finite element analysis using USFOS and discussed with respect to the turbine natural frequencies and eigenmodes, contact forces and dynamic responses. A parametric analysis is conducted for ship-OWT collisions, exploring different impact scenarios by varying ship sizes, contact stiffnesses, and initial impact velocities. The proposed approach can serve as a promising tool for accidental load response analysis and the design of monopile OWTs.

Interface superconductivity in the point contact between topological semimetals polymorphic PtBi2 and ferromagnetic tips

Topological semimetals, possessing topologically non-trivial band structures, serve as excellent platforms for realizing topological superconductivity through hard point-contact experiments. In this study, we successfully induce superconductivity in the three-dimensional Dirac semimetal, cubic PtBi2, using ferromagnetic and paramagnetic tips in hard point contact experiments. The induced superconductivity is proven to be insensitive to ferromagnetism and exhibits unconventional features in the point-contact spectra. The highest superconducting transition temperature (Tc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$T_{\\mathrm{c}}$\\end{document}) reaches approximately 5.1 K, and the Tc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$T_{\\mathrm{c}}$\\end{document} values are proven to have a positive correlation with the coupling between the tip and the sample. Furthermore, we extend our point-contact experiments to trigonal PtBi2, a material possessing a type-I Weyl semimetal band structure and triply degenerate points proximate to the Fermi level. Utilizing both ferromagnetic Ni tips and paramagnetic Ag tips, we successfully enhance superconductivity with a Tc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$T_{\\mathrm{c}}$\\end{document} of up to 3.0 K in this material. The findings from point-contact measurements reveal that the enhanced superconductivity is compatible with ferromagnetism and the magnetism of the tip can affect the symmetry of the enhanced superconducting state. Given that the lattice structure remains stable under pressure up to 51.2 GPa for cubic PtBi2 and 12.9 GPa for trigonal PtBi2, the emergent superconducting states observed in these two PtBi2 materials could inherit their topological nontrivial nature and be promising candidates for topological superconductor.

Passive Realization of Object Spatial Compliance by a Hand Having Multiple Four-Joint Hard Fingers

Abstract This paper presents an approach to passively realize any specified object spatial compliance using the grasp of a robotic hand. The kinematically anthropomorphic hands considered have multiple 4-joint fingers making hard point contact with the held object, and the joints of each finger have selectable passive elastic behavior. It is shown that the space of passively realizable compliances is restricted by the kinematic structure of the anthropomorphic hand. To achieve an arbitrary compliant behavior, fingers must be able to adjust their orientation. Synthesis procedures for grasps having 3, 4, and 5 or more fingers are developed. These procedures identify the finger configurations and the individual finger joint compliances needed to passively achieve any specified spatial object compliance matrix in the 20-dimensional subspace of grasp-realizable behaviors.

Mimicking Axons by Conductive Metal Lines Formed by Photocatalytically Grown Gold

Nanoionic memristive devices based on the field−driven migration of metal cations and oxygen vacancies have gathered high interest in the scientific community for their capability to technically mimic synaptic connections. Less attention has been given to long−range global plasticity in artificial neuronal networks. The aim of our research is to use light−stimulated growth of gold metal lines to technically mimic the growth of long−range axonal connections for neuromorphic computing architectures. For this purpose, we investigate the formation of metal lines by UV−light−stimulus−driven photocatalytic deposition of gold on titanium dioxide layers. In this study, we present a significant contribution that stems from our active involvement in CRC 1461- Neurotronics, a pivotal initiative funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). Our research falls under Project-ID 434434223 – SFB 1461, within the broader context of Bio-inspired information pathways.0.8-mm wide photoactive titanium dioxide lines are defined by photolithography on a Sodalime glass substrate. We deposited a 70 nm thick titanium dioxide line on a 10 nm thick indium tin oxide adhesion layer by DC sputtering. The substrate was then heat treated for 90 minutes at 400°C and subsequently cooled on a metal plate to achieve the photocatalytically active anatase phase of titanium dioxide [1]. The growth process is conducted in a beaker by reduction from an aqueous gold chloride precursor solution (HAuCl4). In each step of the growth process, the substrate is placed in a beaker containing 15 ml of the precursor. The solution is obtained by dissolving 15 mg of HAuCl4 powder in 60 ml of deionized water. We utilize a UV LED with the peak wavelength of 365 nm and an approximate intensity of 1.8 - 2.7 mW/cm² to illuminate the sample in the beaker. The illumination time and UV intensity are crucial for this dynamic process. Here, we illuminated the sample for 12 hours and refreshed the solution every 2 hours. After each refreshment of the solution, the substrate is washed thoroughly with deionized (DI) water and is dried under nitrogen gas. We analyze the surface properties of grown gold utilizing scanning electron microscopy (SEM) and measure the conductance of the grown lines by applying voltage via the needles of a hard contact probe station.In the first experiments the growth of gold clusters on the surface is observed instead of the homogeneous gold coverage of the photolithographically defined titanium dioxide lines, which are needed for long-range electrical connections. Then, we coincidentally observed that the presence of a scratch on the titanium dioxide line led to the growth of continuous gold lines on the damaged area. Subsequently, deliberate scratches were introduced manually using tweezers, varying in both size and thickness. SEM images depict islands and covered areas, with notable growth observed on the scratched regions. Remarkably, wider scratches exhibit a proportionally increased width of the grown lines, and a uniform line devoid of any gaps is distinctly visible on broader scratches. We observed particle growth on thinner lines. However, unlike the uniform alignment observed in wider scratches, these particles did not coalesce into a continuous line. Instead, they remained separated from each other, exhibiting small gaps between individual particles. The morphological analysis of the grown gold line using SEM reveals a crystalline morphology of particles.As the primary objective of this research is to mimic axons with gold lines, ensuring conductivity is crucial for obtaining long−range electrical connections mimicking axons. To achieve this, voltage was applied using the needles of a hard contact probe station, and the resulting current was measured. The linear behavior observed in the I–V diagram of the wider line serves as a confirmation of its conductance (≈0.003 S).

Pediatric keratoconus in a tertiary eye hospital in Eastern province, Saudi Arabia: Patient characteristics and management outcomes.

This study investigates pediatric keratoconus in a tertiary eye hospital in Eastern Province, Saudi Arabia, aiming to understand the presenting features and treatment outcomes in this high-prevalence region. The research addresses pediatric keratoconus clinical profile and management strategies. A retrospective cohort study was conducted from 2022 to 2023, reviewing medical records of pediatric keratoconus patients. Demographic data, clinical characteristics, risk factors, presenting symptoms, and treatment outcomes were recorded. Severity staging was performed based on Amsler-Krumeich's classification. The study included 218 eyes from 109 pediatric keratoconus patients, with 65% of male and 35% of female patients. Decreased vision was the most common symptom (92%), and risk factors included a family history of keratoconus (9%) and vernal keratoconjunctivitis (6%). Stage 1 was the most frequent in both age groups (<14 years and ≥ 14 years). Treatment strategies included corneal collagen cross-linking (CXL), hard contact lenses, corneal rings, deep anterior lamellar keratoplasty (DLK), and penetrating keratoplasty. Significant improvements were observed in visual acuity, refractive errors, and tomographic parameters following these interventions. This study provides valuable insights into pediatric keratoconus in Saudi Arabia, emphasizing the importance of early diagnosis and interventions for better outcomes. Larger, multicenter prospective studies are essential for a comprehensive understanding of pediatric keratoconus and its optimal management. The findings contribute to the knowledge base and guide future research to improve patient quality of life.

Past human decision-making based on stone tool performance: Experiments to test the influence of raw material variability and edge angle design on tool function

One of the main interests in the interpretation of the archaeological record and its variability within and through time and space is the production and use of past human stone tool technologies. Tool design and function are inevitably intertwined and strongly related to tool use. Understanding tool design provides information about early human technological adaptations and reflects human behaviour in the sense of conscious or unconscious decision-making. Nevertheless, the reason for major changes (including novelties, innovations, and loss) in past human stone tool technology is still poorly understood. A comprehensive approach focusing on tool function (What was the tool meant for?) and use (What was the tool used for?) can help to overcome this gap. While tool function (including performance) can be investigated experimentally, tool use can be addressed with use-wear analyses. These questions can be best investigated on technological systems showing little tool variability but strong evidence of maintenance and long-term use, such as Middle Palaeolithic industries.The Late Middle Palaeolithic record of Central and Eastern Europe is marked by the emergence of an asymmetric tool-type called Keilmesser (bifacial backed knives). Due to their sophisticated morphology, Keilmesser as a case study offer the potential to address aspects of raw material selection, tool production, maintenance, and reworking.This paper presents the results of an experiment designed to study the tool performance of Keilmesser from three archaeological sites, namely Balver Höhle, the Upper site of Buhlen and Grotte de Ramioul by testing raw material, edge angle and movement as independent variables. A highly controlled, sequential experiment was conducted using a mechanical device performing unidirectional cutting and carving movements on hard contact material. Results demonstrate the possibility to perform the mentioned task with 35° and 45° edge angles, maintaining function, albeit at differing levels of efficiency. The data has a direct impact on the interpretation of the archaeological assemblages regarding aspects such as stone tool morphology and resharpening. At the same time, the study highlights the importance of raw material analysis to understand the variability in the archaeological record and the implications on past human decision-making strategies.

A Comparison of Madaline and Perceptron Algorithms on Classification with Quantum Computing Approach

The fundamental problem in this research is to explore a more profound understanding regarding both performance and efficiency in quantity computing. Successful implementation of algorithms in computational computing environments can unlock the potential for significant improvements in information processing and neural network modelling. This research focuses on developing the Madaline and Perceptron algorithm using a quantum approach. This study compares the two algorithms regarding the accuracy and epoch of the test results. The dataset used in this study is using a lens dataset. There are four attributes: 1) patient age: young, pre-presbyopia, presbyopia 2) eyeglass prescription: myopia, hypermetropia 3) astigmatic: no, yes. 4) tear production rate: reduced, normal. There are three classes: 1) patients must have hard contact lenses installed, 2) patients must have soft contact lenses installed, and 3) patients cannot have contact lenses installed. The number of data is 24 data. The result of this research is the development of the Madaline and Perceptron algorithms with a quantum computing approach. Comparing these algorithms shows the best accuracy is the Perceptron algorithm, namely 100%. In comparison, Madaline is 62.5%, and the smallest epoch is the Madaline algorithm, namely 4 epochs, while the smallest Perceptron epoch is 317. This research significantly contributes to developing computing and neural networks, with potential applications extending from data processing to more accurate modelling in artificial intelligence, data analysis and understanding complex patterns.

Effect of elastic deformation on the heat transfer characteristic of refrigerator gasket based on static analysis of structural assemblies

ABSTRACT Soft and hard contact deformation is most common issue of the refrigerator gasket and it has almost been ignored in previous studies. In this paper, the novelty is to propose a thermal-solid coupling simulation to study the effect of assembly states on the heat transfer of gaskets, improving the accuracy of heat transfer simulation analysis. The numerical results indicate that the calculated temperature based on physical model of assembly state is closer to measured temperature. The assembly distance affects the assembly state of the gasket by changing the contact positions and lengths of contact interfaces. As a result, the heat transfer path and condition at the gasket region also changes. As the deformation increases form −1.0 mm to 5.0 mm, the heat leakage load of gasket rises firstly and then falls, in the range of 1.61 ~ 3.33 W•m−1. The heat leakage at the transfer paths of internal cold air, outer shell and cold bridge accounts for over 20%. Thus, it is recommended to reduce the contact interface length of internal cold air, increase the thermal resistance of auxiliary air-bag, reduce the thermal conductivity and thickness of magnetic strip and increase the contact thermal resistance of cold bridge.

Relationship Between Contact Lens Wear and the Risk of Acquired Blepharoptosis

Abstract&#x0D; Introduction &amp; Objectives : Contact lens wear has been reported to be associated with acquired blepharoptosis. This literature review aims to summarize and evaluate the risk of acquired blepharoptosis in contact lens wearers.&#x0D; Methods : Literature searching was conducted using three online databases including PubMed, Cochrane Library, and Embase. Search terms such as “contact lens”, “ptosis”, and “blepharoptosis” were included. Reference lists of each study were also assessed for potentially relevant sources. Prospective and retrospective studies as well as meta-analyses and systematic reviews were included.&#x0D; Results : Using relevant search terms in various databases, a total of five articles were included in this review. Four studies suggested that wearing hard or soft contact lenses was significantly associated with blepharoptosis. One study indicated hard contact lens wearers presented blepharoptosis 17.38 times more frequently than non-wearers (OR, 17.38, 95% CI=3.71–81.29), while soft contact lens wearers had 8.12 times more risk of presenting blepharoptosis than non-wearers (OR, 8.12, 95% CI=2.68–24.87). Furthermore, long-term contact lens wear, which was 20 years or more, seemed to have a significant effect on the incidence of blepharoptosis. There was only one study which stated that hard contact lens wear did not lead to acquired blepharoptosis in this review.&#x0D; Conclusion : There is evidence of a clear association between hard or soft contact lens wear and an increased risk of blepharoptosis. Patients wearing contact lenses should be informed of the risk of blepharoptosis, and a history of contact lens use should be sought in all patients who have acquired blepharoptosis.

HUBUNGAN ANTARA PEMAKAIAN LENSA KONTAK DAN RISIKO BLEFAROPTOSIS DIDAPAT

Objectives: Contact lenses (CL) wear has been reported to be associated with acquired blepharoptosis. This literature review aims to summarize and evaluate the risk of acquired blepharoptosis in contact lens wearers. Methods: Literature searching was conducted using three online databases including PubMed, Cochrane Library, and Embase. Search terms such as “contact lens”, “ptosis”, and “blepharoptosis” were included. Reference lists of each study were also assessed for potentially relevant sources. Results: Using relevant search terms in various databases, a total of three articles were included in this review. All studies reviewed were single-center retrospective studies. The three studies suggested that wearing contact lens was significantly associated with blepharoptosis. Long-term contact lens wear, ranging from 15 to 34 years, seemed to have a significant effect on the incidence of blepharoptosis. Hard contact lens (HCL) wear has a greater risk for ptosis to occur than soft contact lens (SCL) wear. Conclusion: There is evidence of a clear association between hard or soft contact lens wear and an increased risk of blepharoptosis. Patients wearing contact lenses should be informed of the risk of blepharoptosis, and a history of contact lens wear should be sought in all patients who have acquired blepharoptosis.

Long-term Prognosis of Pediatric Ocular Disease.

Several problems differentiate the treatment of children, especially those with congenital ocular disease, from adults, including the absence of complaints and the complication of systemic diseases. However, the most challenging is the continuing developing anatomical and functional development and immaturity in children. Consequently, the timing of disease onset and treatment can greatly affect the prognosis, and the prognosis cannot be confirmed without long-term follow-up periods. The prognosis for unilateral congenital cataract is very poor. However, some cases achieved good vision with successful refractive correction and amblyopia therapy, suggesting that long-term parental enthusiasm and adherence are important for the visual prognosis. Penetrating keratoplasty is rarely performed in children, and outcomes at our hospital have been extremely poor for congenital corneal opacity over the past 28 years. The visual prognosis is also poor for large limbal dermoids approaching the center of the cornea, which did not respond to preoperative amblyopia therapy. Consequently, early excision, lamellar keratoplasty, wearing of hard contact lenses, and amblyopia therapy were considered necessary. Treatment of pediatric ocular disease should consider the pros and cons, methods, and timing, especially the development of the pediatric eye and the time of onset of the disease.

A finite element analysis-based approach for blast-resistant design of LNG containment tanks

Inside Liquid Natural Gas (LNG) facilities, ignition of large vapor clouds in a congested region might result in Vapor Cloud Explosions (VCE) leading to high speed blast waves and compromising the structural integrity of equipment and structures. The escalation of an initial blast is referred to as ‘Cascading Effect’. In performing risk assessment of a facility, structural damage of LNG containment tanks due to blast scenarios needs to be considered. This article presents a numerical approach-based methodology to analyze containment structures using Finite Element Analysis (FEA). The objective of this study is to elucidate the critical parameters in blast resistant design of containment tanks. Four major types of containment tanks are studied under representative scenarios of deflagration and detonation. Containment tank geometries were created almost in its entirety and the structural response is modeled with appropriate constitutive relations for steel and concrete. Additionally, pertinent hard contact with friction interaction between the tank inner to outer shell surfaces are assigned. The results indicate that a single containment tank model experienced severe damage in its outer shell under deflagration compared to other types of containment tanks. In the case of double, full and membrane containment tanks cracking in the prestressed concrete wall was observed due tensile damage which is pronounced for detonation than for deflagration cases. It is concluded that single containment tanks are most vulnerable to Cascading Effect. Based on the results of FEA, recommendations are provided for safe practice of designing the structures and maintaining the structural integrity of tanks.

Lower eyelid position before and after blepharoptosis repair

ABSTRACT Purpose This study aimed to examine the changes in lower eyelid position after blepharoptosis surgery and the factors that influence the outcome. Methods We conducted a retrospective study of 155 eyes of 89 patients who underwent blepharoptosis surgery between June 2019 and October 2022. The margin reflex distance (MRD)-1 and MRD-2 were examined preoperatively and 3 months postoperatively in two groups: one with lower scleral show (LSS) (n = 37) and one without LSS (n = 118). The clinical characteristics of the two groups were compared. Results Both the LSS and non-LSS groups showed significant postoperative improvement in MRD-1 scores (p < .01, p < .01, respectively). MRD-2 was significantly reduced in the LSS group, while it remained unchanged in the non-LSS group (p < .01, p = .27, respectively). There were no significant differences between the two groups in age, sex, history of hard contact lens use, preoperative levator function, use of topical steroids, history of endophthalmic surgery, or history of filtration surgery; however, the LSS group significantly used prostaglandin analogs (PGAs) (p = .03). Postoperatively, MRD-2 decreased in 13 eyes (35.1%) and was maintained in 24 eyes (64.9%) in the LSS group and was maintained in all eyes in the non-LSS group. In the LSS group, we also examined the association between postoperative MRD-2 reduction and the use of PGAs and found that more patients with MRD-2 reduction used PGAs (p = .02). Conclusion Lower scleral show in PGAs-associated blepharoptosis is expected to improve after blepharoptosis surgery.

Nonlinear analysis and vibro-impact characteristics of a shaft-bearing assembly

This study investigates the nonlinear frequency response of a shaft-bearing assembly with vibro-impacts occurring at the bearing clearances. The formation of nonlinear behavior as system parameters change is examined, along with the effects of asymmetries in the nominal, inherently symmetric system. The primary effect of increasing the forcing magnitude or decreasing the contact gap sizes is the formation of grazing-induced chaotic solution branches occurring over a wide frequency range near each system resonance. The system's nominal setup has very hard contact stiffness and shows no evidence of isolas or superharmonic resonances over the frequency ranges of interest. Moderate contact stiffnesses cause symmetry breaking and introduce superharmonic resonance branches of primary resonances. Even if some primary resonances are not present due to the system's inherent symmetry, their superharmonic resonances still manifest. Branches of quasiperiodic isolas (isolated resonance branches) are also discovered, along with a cloud of isolas near a high-frequency resonance. Parameter asymmetries are found to produce a few significant changes in behavior: asymmetric linear stiffness, contact stiffness, and gap size could affect the behavior of primary resonant frequencies and isolas.

Parameters of a basic ophthalmic examination that can ensure proper timing of corneal crosslinking in patients with keratoconus.

By the time patients with keratoconus are referred to specialists for treatment, the disease-related thinning of their corneas has already made them ineligible (< 400μm) for corneal crosslinking (CXL). To find basic ophthalmic examination parameters that can ensure proper timing of referral for CXL. We reviewed cases referred to Toyama University Hospital for the treatment of keratoconus from August 2011 to May 2021 to identify the frequency of contraindication due to minimal corneal thickness (MCT) < 400μm at first visit. We performed a receiver operator characteristic (ROC) analysis of basic exam parameters (uncorrected distance visual acuity, corrected distance visual acuity, corrected distance visual acuity with hard contact lens, sphericity, cylindricity, and/or corneal astigmatism) potentially predicting eligibility for CXL. For those with an area under the curve (AUC) > 0.8, we determined cut-off values and calculated sensitivity and specificity. Analyses included 66 eyes of 38 Japanese patients aged 25.0 ± 7.1 yrs (range 12-38 yrs) (56 male eyes and 10 female eyes). Thirty percent of the patients had an MCT < 400μm. The AUC for uncorrected distance visual acuity (UCDVA) was 0.85. A cut-off value of 1.22 (converted to decimal visual acuity: ≥ 0.06) yielded 87% sensitivity and 75% specificity. The AUC for corrected distance visual acuity (CDVA) was 0.90. A cut-off of 0.52 (converted to decimal visual acuity: ≥ 0.3) yielded 89% sensitivity and 75% specificity. It is advisable to refer patients with keratoconus to a specialized facility for CXL when either of the following conditions is present: (i) UCDVA (decimal visual acuity) ≥ 0.06 or (ii) CDVA (decimal visual acuity) ≥ 0.3.

Surface Tensile Strength and Hertzian Fracture Resistance of Patterned Acid-Etched Glass

Patterned acid-etched glasses are frequently used in horizontal glass surfaces that may be walked on, such as floors and staircase treads. These glasses provide useful antislip properties, but the foot traffic cause contact stresses and ageing mechanisms that are poorly understood and can affect the strength of the acid-etched glass. This study explores these strength-reducing effects by undertaking nondestructive and destructive evaluations of two acid-etched glasses with geometrically different surface patterns and comparing their mechanical performance to unetched float glass. In particular, residual surface stress, Hertzian fracture resistance, and fractographic characteristics are determined for each glass type. The surface tensile strength of the glasses is also evaluated by means of destructive flexural tests before and after artificial ageing. The flexural tests reveal that the ridge areas of the acid-etched surface patterns are more susceptible to the formation of digs and deeper surface flaws and are therefore weaker than both the valley areas of the acid-etched pattern and the surface of the unetched float glass. Correspondingly, the acid-etched glass with the highest proportion of ridges was more susceptible to ageing-induced flaws and had the lowest surface tensile strength. The contact (Hertzian) fracture resistance was also significantly affected by the presence of a surface pattern in the acid-etched glass; specifically, the lowest contact strengths were recorded for hard body contact on the ridges of the pattern. The fracture phenomena and new data presented in this paper provide useful insights on the long-term performance of etched patterned glass. The findings can provide the bases for real-world design decisions and for glass forensics.

Noise and Vibration Risk Assessment for the Operators of Crawler Loaders

During work, earth-moving machines generate significant levels of noise and vibration that can be harmful for the operators; therefore the analysis of the noise and vibration conditions at the driving position is of great importance for the risk assessment. Compact loaders have become a pressing challenge as they are extremely hazardous referring to noise and vibration emissions, especially in their crawler version where further relevant noise and vibration are generated by the hard contact between track belt and ground. This paper reports the results of investigations carried out on three crawler compact loaders in different operating conditions. The main purpose was to investigate the noise and vibration values transmitted to the operators in some working conditions and use these data to obtain reliable estimates of the exposure to noise, to whole-body and to hand-arm transmitted vibrations, as well as to evaluate the related risk levels. Vibration signals transmitted to the operator were acquired on the seat and the machine control lever in accordance with the procedures specified in ISO 2631-1 and ISO 5349-1. At the same time, noise signals were acquired at the operator’s ear following the procedure reported in ISO 11201. Vibration signals were also acquired on the cabin floor with the main purpose to evaluate the effectiveness of the machine seats in reducing the vibration transmission. Finally, the noise and vibration exposure risks were evaluated on the basis of the health and safety requirements established in 2003/10/EC and 2002/44/EC Directives.

Local measures of fluctuations in inhomogeneous liquids: statistical mechanics and illustrative applications

We show in detail how three one-body fluctuation profiles, namely the local compressibility, the local thermal susceptibility, and the reduced density, can be obtained from a statistical mechanical many-body description of classical particle-based systems. We present several different and equivalent routes to the definition of each fluctuation profile, facilitating their explicit numerical calculation in inhomogeneous equilibrium systems. This underlying framework is used for the derivation of further properties such as hard wall contact theorems and novel types of inhomogeneous one-body Ornstein–Zernike equations. The practical accessibility of all three fluctuation profiles is exemplified by grand canonical Monte Carlo simulations that we present for hard sphere, Gaussian core and Lennard–Jones fluids in confinement.