Central Hole Diameter Research Articles

Can flowable short-fiber-reinforced resins achieve a strong adhesion to bioceramics?

This study compared the microshear bond strength (μSBS) of four calcium silicate-based cements (CSCs), TheraCal PT (TPT), TheraCal LC (TLC), Biodentine (BD), and Dia-Root Bio MTA (DR), with a short fiber-reinforced composite resin (SFRC). Forty cylindrical acrylic blocks were used, each with a center hole (diameter 5 mm, depth 2 mm). CSCs were placed in the holes (n = 10/group), and the blocks were incubated for 48 h. G-Premio BOND, a self-etching adhesive, was applied to the CSCs surfaces using a micro-applicator for 10 s and then air-dried for 5 s, followed by light curing for 20 s. SFRC materials placed in cylindrical polyethylene capsules (diameter 2 mm, height 2 mm) were polymerized for 20 s and placed over the CSCs. The samples were then incubated at 37°C and 100% humidity for 24 h, and their μSBSs were tested using an "Instron Universal Testing Machine." Data were statistically analyzed using chi-square and Kruskal-Wallis tests. Statistically significant differences were observed between the tested CSCs. The μSBS of TPT (45.17 ± 4.56 MPa) was significantly higher (p < .05) than that of the other materials: BD, TLC, and DR had μSBSs of 29.18 ± 2.86 MPa (p < .05), 23.86 ± 2.84 MPa (p > .05), and 18.08 ± 2.69 MPa (p < .05), respectively. Considering the importance of bond strength for CSC sealing with restorative material, using SFRC over CSC was promising for improving the μSBS, adhesion, and sealing of the material. RESEARCH HIGHLIGHTS: Adhesion is critical to the success of vital pulp restorations. To achieve strong adhesion, the bioceramic material and the resin composite to which it is bonded are very important. In our study, short fiber-reinforced composite resin, which is gaining popularity, was used and found to be a promising material for improved adhesion.

Enhancing four-axis machining center accuracy through interactive fusion of spatiotemporal graph convolutional networks and an error-controlled digital twin system

Mitigating thermal errors constitutes a crucial method for enhancing the machining accuracy of four-axis machining centers. At the heart of effective thermal error control lie the thermal error control platform and a resilient thermal error prediction model. It is imperative to note that thermal errors exhibit intricate dynamic and nonlinear spatiotemporal dependencies. However, prevailing thermal error prediction models tend to primarily focus on temporal features or employ simplistic spatiotemporal characteristics, resulting in diminished accuracy and robustness. Furthermore, the present thermal error compensation system is plagued by a lack of user-friendliness, stemming from its suboptimal execution efficiency. In response to the aforementioned challenges, an innovative approach: the interactive fusion spatiotemporal graph convolutional network is proposed. This novel model is specifically designed to capture the intricate dynamic spatiotemporal dependencies inherent in thermal errors. The interactive fusion spatiotemporal graph convolutional network model consists of three essential components: a bilinear temporal convolutional network, a multi-layer spatiotemporal module, and a linear module. These components work in harmony to comprehensively extract both global and local spatiotemporal features. Subsequently, a mapping relationship between thermal errors and compensation components is established, laying the foundation for theoretical advancements in thermal error compensation within the realm of four-axis machining centers. A digital twin system framework tailored for error control is devised, which leverages cloud-edge computing to enable dynamic control and real-time monitoring of thermal errors. To assess the effectiveness of this digital twin system framework and the interactive fusion spatiotemporal graph convolutional network model, a series of rigorous experiments were conducted. The oriented to error-controlled digital twin system coupled with the interactive fusion spatiotemporal graph convolutional network model yielded exceptional machining accuracy, resulting in minimal geometric disparities of [−3.0 μm, 3.0 μm] for the central hole diameter D and [−3.5 μm, 4.0 μm] for the hole distance H.

Numerical analysis of a compact all-fiber polarization beam splitter based on dual-core photonic crystal fiber with As2S3 thin layer

Modern-day optical systems are evolving towards miniaturization and integration, leading to higher performance demands for polarizing beam splitters (PBSs). A simple-structure and high-performance PBS based on dual-core photonic crystal fiber (DC-PCF) with As2S3 layer is proposed. The finite element method (FEM) and classical coupled-mode theory (CMT) are utilized to investigate the performance of this PBS. Simulation results demonstrate that the proposed PBS can achieve a minimum length of 2.65 mm, a minimum extinction ratio of −64 dB, an operating bandwidth of 420 nm, and a minimum insertion loss of 0.03 dB when the optimal parameters include cladding hole diameter of 1.0 μm, central hole diameter of 2.0 μm, lattice spacing of 2.0 μm, and As2S3 ring layer thickness of 50 nm. Moreover, it also possesses a high birefringence of 3.58 × 10−3 and a negative dispersion of −30 ps/km/nm at 1.55 μm. It is believed that the proposed PBS holds great potential to become a critical device in optical multiplexing technologies.

Residual dispersion compensation photonic crystal fiber based on simulated annealing algorithm and Livelink data interaction

An octagonal photonic crystal fiber (O-PCF) structure with equal air hole diameter of the cladding is proposed for residual dispersion compensation, and a high refractive index material SF57 is introduced in the core region to make it have the advantages of high negative dispersion, low attenuation loss, low fabrication difficulty. Due to the symmetric structure, no additional polarization control is required in the dispersion compensation process, which further reduces the production cost. Using Livelink data interaction not only accelerates the modeling of O-PCF, but also enables the effective refractive index of HE11 to be unattended continuously searched. Furthermore, simulated annealing algorithm is used to reverse design the structural parameters of cladding air hole diameter and central solid hole diameter. The results show that, based on the simulated annealing algorithm interacting with Livelink data, the optimize efficiency, design accuracy and dispersion characteristics are improved. The ultra-flat high negative dispersion O-PCF can be reverse designed in the S + C + L and S + C + L + U bands which shows the average dispersion of −847.34 ps/(nm·km) and −752.90 ps/(nm·km) with the absolute dispersion of only ±7.25 ps/(nm·km) and ±10.28 ps/(nm·km), respectively. The designed RDCF is tolerant to ±1% and ±2% variation of the central solid hole diameter and the cladding air hole diameter during fabrication, respectively. The combination of simulated annealing algorithm and Livelink data interaction provides an efficient method for reverse design of PCF.

Study on the Influence of Central Hole Diameter in a Wire Mesh Electrode on Ionic Wind Characteristics.

Ionic wind, which is generated by a corona discharge, is a promising field that offers significant advantages by directly converting electrical energy into kinetic energy. Because of the electrical characteristics of ionic wind, most studies aiming to improve the performance of ionic wind generators have focused on modifying the geometry of electrode configurations. A mesh-type electrode is one of the electrodes used as a collecting electrode in an ionic wind generator. Using a mesh electrode results in decreased momentum of the ionic wind and increased pressure drop due to frictional loss of the flow. In this study, to minimize the reduction in momentum, a mesh electrode with a central hole was proposed and investigated. Experiments were conducted with the configuration of a needle and mesh with the central hole. These experiments analyzed the effect of the central hole diameter and the distance between the needle and the mesh electrodes on the electrical and physical characteristics of the ionic wind. The addition of the central hole led to a higher average velocity and lower current, thus resulting in increased energy conversion efficiency. The presented configuration offers a simple geometry without electrical and physical interference from complex configurations, and it is considered to have the potential to improve energy conversion efficiency and optimize ionic wind flow.

Pengaruh Variasi Tebal Orifice dan Bilangan Reynolds (Re) terhadap Penurunan Tekanan (Pressure Drop) pada Entrance Region

Orifice is a device that is placed in a pipe flow to inhibit the flow of fluid and cause a pressure drop. The measurement of the flow rate (flow rate) is obtained from the difference in pressure due to the pressure drop. In this study, it analyzed the influence of differences in plate orifice thickness variations used ranging from 2 mm to 4 mm thick with variations in increments every 0.5 mm with an orifice center hole diameter of 1.5 cm. Orifice placement is placed in an area whose speed profile is still changing or called the entrance region with a pipe diameter used 2.54 cm (1 Inch) diameter in the pipe. Then along the entrance area are paired 12 piezometer points along 75 cm with a position of laying 6 piezometer points before the orifice valve and 6 piezometer points after the orifice valve and in this experiment set the Re value to 3 Variations of Re, namely Re 1: 9784.5; Re2: 14647.5; Re 3: 19510.45 and this experiment was carried out at a temperature of 27 °C. In this study, the results were obtained for the highest irrecoverable pressure drop value located in the flow discharge with Re 19510.45 and at the thickness of the plate orifice 4 mm with an irrecoverable pressure drop value of 3033.01 Pa and while for the lowest irrecoverable pressure drop value, it was located in the flow discharge with a value of Re 9784.5 at an orifice plate thickness of 2 mm with an irrecoverable pressure drop value of 548.26 Pa. The highest discharge of coefficient (Cd) value lies in the flow discharge with a value of Re 14647.5 at the plate orifice thickness of 3.5 with a Cd value of 0.718 and while for the lowest discharge of coefficient (Cd) value lies in the flow discharge with Re 14647.5 with an orifice plate thickness of 2 mm with a Cd value of 0.609.

Experimental and numerical research on opening size effect of novel short fiber reinforced composite laminates

This study investigates the opening size effect of a novel short fiber reinforced quasi-isotropic composite laminate with unidirectionally arrayed chopped strands (UACS) under tensile load by approaches of simulations and experiments. The layup of [45/0/-45/90]s was used to fabricate novel carbon fiber laminates with various central hole diameter from 4 mm to 10 mm. Low notch sensitivity and strength reduction rate were observed in UACS open-hole laminates. It was found that when the width diameter ratio (d/w) of UACS laminate with open-hole is less than 20%, 80% of the original strength can be maintained, which can greatly reduce the design safety factor. Compared with continuous fiber laminates, high increase rate of strength reduction rate was induced by bi-angled slits with the increasing of open hole diameter. The strain distribution around the hole was affected significantly by bi-angled slits, which also inhibited the initiation and propagation of delamination effectively. The strain concentration factor of UACS laminates increases with the increasing open hole diameter. The damage progression of notched and unnotched UACS laminates were analyzed by simulation method, which are consistent well with experimental results.

The effectiveness of patch repairs to restore the impact properties of carbon-fibre reinforced-plastic composites

The present paper studies the low-velocity impact testing of carbon-fibre reinforced-plastic (CFRP) pristine and patch-repair CFRP panels. Firstly, the effect of repeated impacts on the pristine CFRP damage growth is considered at impact energies of 7.5, 10.5 and 30 J. Secondly, such tests lead to a single-sided, patch-repair panel being manufactured by removing a 40 mm diameter central hole, to act as the ‘damaged area’, from the parent CFRP panel and then adhesively-bonding a circular CFRP patch-repair over the hole so generated. Various diameters and thicknesses for the CFRP patch-repair are employed and, in some cases, a CFRP circular plug is also used to fill the hole created by removal of the parent composite. The measured load versus time, and load versus displacement, traces are compared. Further, the extent and location of any interlaminar damage, i.e. delaminations between the plies of the CFRP, caused by the impact event are mapped using an ultrasonic C-scan technique. It is shown that single-sided patch repairs can be very effective in restoring the impact performance of damaged CFRP panels.

On rotor hub design for shrouded hydrokinetic turbines

The effect of hub length and axial location on the performance of shrouded hydrokinetic turbines has been investigated using axisymmetric actuator disk simulations. Five systems with different hubs (or without a hub, for reference) are considered with a common shroud design. Flow separation on the hub was found to be detrimental to performance, and to be sensitive to rotor loading, leading to unacceptable off-design performance. When the thrust coefficient, CT, is below the optimal value of 8/9, increasing CT promotes flow separation on the central hub; continued increases beyond this value facilitate reattachment. Flow separation on the hub was avoided altogether when most of the hub was placed upstream of the rotor plane—contrary to the convention for unshrouded turbines—where the shroud geometry lends a favorable pressure gradient. This latter design achieved performance in close agreement with the open-centered design, which is recommended when feasible to avoid the risks of hub-flow separation. With a central hole diameter of 0.228D, where D is the rotor diameter, a penalty of <5% in optimal performance was found compared to an actuator disk spanning the entire shroud throat. Lastly, a discussion of the relationship between total system thrust and power extraction is offered.

Sensitivity and linearity enhanced wide-detection range surface-plasmon-resonance photonic-crystal-fiber sensor

A refractive-index (RI) sensor based on photonic crystal fiber (PCF) and surface plasmon resonance (SPR) is proposed and demonstrated in this paper. The influences induced by the changes of the diameter of gold nanowire, air-hole spacing, diameter of central hole and diameter of the air hole on both sides of central hole are investigated to analyze and optimize the performances of the SPR-PCF sensor. It is indicated that the proposed sensor is suitable for the detection of the RI of material in the range from 1.15 to 1.45. Moreover, the optimized RI sensitivity can reach −5893.9 nm/RIU and the optimized R2 can be larger than 0.999. Detections of the alcohol with different concentrations are carried out to demonstrate the performance of the SPR-PCF. The sensitivities in both polarization directions are −192 nm/% and −198 nm/% when the concentration is changed from 10% to 87%. Moreover, the sensitivities for RI-detection are −5900 nm/RIU and −6116 nm/RIU with the corresponding R2 larger than 0.9993 in both polarization-directions. Our detailed results will help to understand the SPR phenomenon in hexagonal PCF, and promote the realization and application of SPR-PCF sensors.

Design Analysis of Multisample Single-Analyte Surface Plasmon Resonance Biosensor Based on D-Shape Photonic Crystal Fibers

This paper dealt with the analysis of a surface plasmon resonance (SPR)-based D-shape photonic crystal fiber (PCF) biosensor for the detection of multimolecules present in a single analyte or simultaneous detection of more than one samples of an analyte. A spatially distributed metallic layer of two plasmonic metals is deposited on the outer flat surface of a D-shaped PCF. Two metals generate two resonance peaks which can detect more than one sample of analyte simultaneously. The analytes are floated onto the flat surface of D-shaped PCF. The mode analysis of proposed sensor is done using finite element method (FEM) with perfectly matched layer. In this study, it can be seen that spatially distributed bimetallic layers can detect more than one sample of analyte simultaneously. The different dimensions of spatially distributed bimetallic SPR-based D-shape PCF sensor are also optimized with respect to center hole diameter, first air hole ring diameter, metal layer thickness and the depth of D-shape. It is also observed that the two SPR wavelengths can be controlled slightly by varying these parameters. It has been seen that for some optimal set of dimensions with the same sensitivity, the confinement loss of the plasmonic peaks is higher. This property may be useful in the applications, where one can sense more than two molecules or more than two samples for the single analyte.

Influence of Etching Mode and Composite Type on Bond Strength to Biodentine Using a “No-Wait” Universal Adhesive

The purpose of this study was to compare the shear bond strength (SBS) of four resin-based composite materials to a silicate-based cement using a “no-wait” universal bond with self-etch (SE) and etch-and-rinse (ER) modes. Acrylic blocks (n=80, 2mm depth, 5mm diameter central hole) were prepared. The holes were filled with BiodentineTM (BD) and divided into 4 main groups (n=20) according to the composite resin type used: Group FZ250: FiltekTM Z250 Universal Restorative (microhybrid), Group SDR: SDR Plus U Bulk Fill Flowable (low-viscosity bulk-fill), Group FBP: FiltekTM Bulk Fill Posterior (high-viscosity bulk-fill), Group EF: EsFlow™ Universal Flowable Composite (nanohybrid). A ‘no-wait’ universal bond (Clearfil Universal Bond Quick) was used for bonding application. Then each group was divided into 2 subgroups according to the etching mode applied (ER and SE). SBSs were measured and stereomicroscope was used to identify the failure modes. Selected samples of fracture surfaces were imaged by SEM. Tukey’s post-hoc and One-way ANOVA tests were used to analyze data. There were statistically significant differences among the composite groups (p&lt;0.05). When SDR showed the highest bond strength values in SE (17.13 ± 2.98 MPa) mode, FBP showed the lowest bond strength values in ER (8.89 ± 2.46 MPa) mode. The mean SBS was not different between the SE and ER modes (p&gt; 0.05). The SBS of BD to the resin composites depends on the composite type but application of the ‘no-wait’ universal bond in different etching modes is regardless of the SBS of BD to resin composites.

A hollow exponential ultrasonic horn for aluminum melt degassing under power ultrasound and rotating flow field

To meet the need of aluminum melt degassing, a hollow exponential ultrasonic horn was proposed. The numerical analysis showed that the amplification factor and shape factor of the horn will increase with the increasing central hole diameter. When the hole diameter is less than 20 mm, they increase slowly while rapidly once the hole diameter excessed 35 mm. The modal analysis and experiments indicated that the resonance frequencies of all the horns are very close to the set frequency, and the errors are less than 3%. Although the displacement amplitude differences are both more than 20 µm, the central hole horn is larger, which is consistent with the result of modal analysis. A simple aluminum melt degassing system employing the proposed hollow horn and rotary impeller was used to experiment on ZL101A aluminum melt, and the results indicated the more satisfactory degassing efficiency can be got by using the appropriate parameters.

Design of buckling and damage resistant steered fibre composite laminates using trellis shear kinematics

A Matlab®-based numerical tool, ‘SteerFab’, is developed to predict steered fibre patterns and to analyse the mechanical properties of the resulting variable stiffness panels using the finite element software, Abaqus™. Based on trellis shear kinematics [1], both the steered fibre pattern and the shape of the corresponding initial undeformed sheet can be created by SteerFab. Two types of rectangular plates measuring 300 mm × 400 mm are considered in this numerical study, one with and one without a 90 mm diameter central hole. For the plate with a hole, the finite element analysis predicts that the optimised steered-fibre pattern achieves similar improvements for both a carbon-epoxy composite (~6%) and a glass–epoxy composite (~7%) in terms of buckling resistance load, while failure load is increased by about 5% for a carbon-epoxy composite and 10% for a glass–epoxy composite compared to the best performing equivalent straight-fibre laminates.

Development of Low-Cost Cable Twister for 3.6 m Telescope at ARIES

In-house design and development of cost-effective cable twister was undertaken at ARIES for back-end instruments of 3.6[Formula: see text]m telescope at Devasthal site located in central Himalayan region of Uttarakhand state in India. Cable twister was designed to route the critical cables such as cryo/helium flexible lines, electrical cables, optical fiber cables and network cables, etc. of various back-end instruments on axial and side ports of 3.6[Formula: see text]m telescope. Designing a space constrained cable twister passing through only 350[Formula: see text]mm diameter central hole available in telescope pier was a challenging task. Design was analyzed with cables at different twister positions for telescope azimuth rotation from 0 to [Formula: see text]. Flexible design, easy routing of cables and quick detachable characteristic of cable twister make it convenient for routing cables of back-end instruments of 3.6[Formula: see text]m telescope. The twister was economically manufactured in-house at ARIES mechanical workshop, assembled, installed and tested with 3.6[Formula: see text]m telescope. Provision for changing of separator plates having different numbers and sizes of holes makes it versatile for the different types of cables in back-end instruments. This paper presents the economical design, analysis, manufacturing, assembly, installation and testing of cable twister with 3.6[Formula: see text]m telescope.

Comparison study of mechanical and dynamic vibration properties of hole defect introduced in hybrid polymer composite

The need for hybrid composites has increased because it includes the advantages both of synthetic glass and natural fibers. In this research work, a hybrid composite has been developed using a glass and coir fiber which has been subjected to moisture, tensile with and without the hole, flexural and dynamic properties. The glass fiber-coconut coir-glass fiber (G-C-G) hybrid composite was made by hand layup technique. The dynamical properties of tensile and open-hole tensile composites were measured by a free vibration technique. SEM analysis on fractured surfaces of the composite was also performed. The results showed that there was an appreciable rise in the moisture absorption capacity of the composites. Tensile testing showed that there was a decrease in tensile strength and modulus with increases in center hole diameter. Results of the fracture study indicated that the fiber-matrix interface improved with fiber treatment. The mechanical properties of hybrid composites were abruptly decreased with a hole diameter of 6 mm. The damping ratio and natural frequency of composite without tensile hole show higher value due to undisturbed in fiber strength.

Theoretical and Experimental Study on Damage Properties of Surrounding Rock under High‐Frequency Constant Impact Load

This paper aims to investigate the mechanics and damage properties of granite by drilling a center hole in Φ50 × 100 mm standard granite specimens under high‐frequency constant impact load and then applying them to the uniaxial compression experiment through the INSTRON 1346 universal material testing machine. According to the experimental results, under constant impact load, as the center hole diameter increases, the peak stress of the rock specimen increases accordingly and the effective elastic modulus of the rock specimen decreases first and then increases gradually. In this study, by theoretical analysis of the surrounding rock damage caused under high‐frequency impact load, a statistical damage constitutive model that has taken surrounding rock damage into consideration is established on the basis of the Weibull distribution. Meanwhile, the experimental curve is obtained to analyze the damage and damage radius of surrounding rock under high‐frequency impact load. The results show that the surrounding rock damage and damage ratio (the ratio of damage radius to center hole radius) of rock decrease with the increase of the center hole diameter. This model that can effectively describe the damage laws of surrounding rock under impact load serves as a guide for the design and development of composite rock‐drilling tools.

Experimental study on pollutant emissions in the novel combined porous-free flame burner

This study intends to measure the pollutant emissions in the novel combined porous-free flame burner and compare it with porous burner experimentally. In this regard, a comparison of the porous-free flame burner and porous burner is done and the effect of the diameter of the hole that is created at the center of the porous medium is studied. In the following, the effects of pore density of the porous medium, firing rate and porous medium material on pollutant emissions are analyzed. The results show that CO concentration in the porous-free flame burner is lower than that of the porous burner and that an increase in the central hole diameter leads to a decrease in CO emission. Furthermore, as the pore density of the porous medium increases, CO concentration increases and for a higher firing rate, CO emission decreases. Also, when the Al2O3 porous medium is used, CO concentration decreases compare to that of SiC porous medium. Measuring NOx emission shows that NOx concentration changes only with varying the equivalence ratio and other parameters have no significant effect on NOx emission.

Prototype screwdriver stopper to avoid intracranial penetration injury.

Screwdriver slipping from the tapping screw head (screwdriver slip) represents a very dangerous situation that leads to the risk of entry into the intracranial operation field. We have developed a screwdriver stopper device to attach to the top of the screwdriver in order to prevent intracranial penetration injuries. We performed 48 craniotomies in our institute. The instrument is made from clear acrylic with a central hole (diameter, 3mm). We checked the number of screwdriver slip events, as a precursor to intracranial penetration injury, in screwdrivers from five different companies, and compared the results. We used 496 tapping screws in 512 tightening procedures. Although screwdriver slip occurred at an overall rate of 17/512(3.3%), we completely avoided serious intracranial penetration injuries. No significant differences in rates of screwdriver slip were seen between the five companies (χ2 test, p = 0.997). Screwdriver slip is a precursor to intracranial penetration injury, but cannot be avoided with cross-type screwdrivers. Many neurosurgeons may be operating without knowledge of the potential risk of intracranial penetration injury. The screwdriver stopper described herein may prove extremely useful for preventing intracranial penetration injuries during neurological surgery.

Features of CO2 fracturing deduced from acoustic emission and microscopy in laboratory experiments

AbstractWe conducted hydraulic fracturing (HF) experiments on 170 mm cubic granite specimens with a 20 mm diameter central hole to investigate how fluid viscosity affects HF process and crack properties. In experiments using supercritical carbon dioxide (SC‐CO2), liquid carbon dioxide (L‐CO2), water, and viscous oil with viscosity of 0.051–336.6 mPa · s, we compared the results for breakdown pressure, the distribution and fracturing mechanism of acoustic emission, and the microstructure of induced cracks revealed by using an acrylic resin containing a fluorescent compound. Fracturing with low‐viscosity fluid induced three‐dimensionally sinuous cracks with many secondary branches, which seem to be desirable pathways for enhanced geothermal system, shale gas recovery, and other processes.