Inside Of Hole Research Articles

Hole quality geometrical measurement and surface roughness for α-Phase titanium alloy (α-Ti-6Al-4V) materials by using L-PBF (laser powder bed fusion) orthopedic implant application

This study examines the quality of circular-hole 3D-printed objects using laser powder bed fusion (L-PBF) on Ti-6Al-4V titanium alloy that typically used for orthopedic implants. Meanwhile measuring surface roughness and hole dimension deviations in AM specimens is very challenging. Thus, the specimens were printed with varying process parameters, followed by an L9 orthogonal array experiment, where parameters included laser power (LP) at 175, 185, and 195 W; scanning speed (SS) at 600, 900, and 1200 mm/s; and hatch distance (HD) at 70, 90, and 110 µm. Thus the, minimum surface roughness values are Ra 2.4 µm for the top surface and Ra 16.06 µm for the inside hole curve. Whereas the smallest hole deviations are 0.1102 mm for external and 0.2094 mm for internal diameters. Therefore, this analysis include FESEM, EDX, XRD, profilometry and stereomicroscopy. Where the best settings are LP 195 W, SS 900 mm/s, and HD 70 µm, producing well-fused, uniform α-phase Ti-6Al-4V specimens that are suitable for biomedical applications.

Experimental study on the effect of inverted aperture plate temperature on frosting characteristics under rising flow considering edge effect

To reduce the negative impact of frost formation on cold surfaces in low-temperature environments, metal wire mesh can be set in the air flow direction from the cold surface to reduce air humidity. To quantitatively determine the effectiveness of dehumidification after passing through a metal wire, the frosting process needs to be studied. To analyze the mechanism of frost formation under the horizontal wire mesh surface, the wire mesh was simplified as a flat plate with holes, or aperture plate, with plate temperature varying at a range of -15.0 °C to -5.0 °C. The results show that, as the plate temperature decreases, the droplet condensation and growth and droplet solidification stages gradually decrease, the average frost layer thickness and frost layer growth rate rise, and overall frost layer surface roughness increases. For a frosting duration of 1,800 s, compared to -5.0 °C, the average frost layer thickness from -7.5 °C to -15.0 °C inside the hole increased by 56.68 % and 156.41 %, while the plate edge region away from the hole increased by 40.76 % and 169.92 %, respectively. The reverse melting frequency gap between the inside hole region and the plate edge region away from the hole increases with the decreasing aperture plate temperature. At -15.0 °C, the reverse melting frequency inside the hole is 5.00 × 10−3 Hz lower than in the region of the plate edge away from the hole. The results of this article are beneficial for understanding the frosting process of wire mesh or perforated-fin heat exchanger.

Determination of Variation of Mass with Gravity

The paper demonstrates that the theory of mass and gravity in the existing normally acknowledged version of theory of gravitational red-shift is completely erroneous. What makes it erroneous is that the frequency of particle in a gravitational field is considered to change depending on its location while mass of particle is treated as constant parameter. This paper predicts that a body in a gravitational field of escape velocity Ve will be more massive by a factor of 1 + (Ve2/C2) , where C is the speed of light, as compared to mass of a similar body outside the field. It manifests that mass of a body measured at earth surface is different than actual mass because of the influence of gravity. If m' and m denote mass of body within and beyond the gravitational field respectively, then the mass (m') measured at earth surface as compared to actual mass (m) is given by the formula m' = m (1+1.39 × 10-9). It reveals that an actual relative mass change at earth m' - m/m = 1.39 × 10-9) is extremely small, with change measure in nanogram. Based on this postulate of variation of mass with gravity, the correct criteria for a particle to be inside black hole turns out to be m'>2m. Therefore, a gravitational field is a black hole if the mass of a body inside the field will be more than two times of its actual mass. In this highly interesting topic, the particular purpose is to present a succinct and carefully reasoned account of new aspect of gravitational red shift which properly allows to determine the change of mass with gravity.

The acoustic performances of a subwavelength hierarchical honeycomb structure: Analytical, numerical, and experimental investigations.

This paper proposes a subwavelength hierarchical honeycomb structure (SHHS) with a compact lateral dimension and double-band perfect absorption in low frequencies. Unlike the conventional micro-perforated panel (MPP)-honeycomb sandwich absorber, this structure has an additional internal honeycomb with a perforated wall. Therefore, there are two resonant cavities in the SHHS to realize multiple absorption peaks. Analytical, numerical, and experimental investigations are performed to study the proposed system's acoustic performance in absorption. The SSHS is simplified into four parts and its analytical model is constructed by combining various analytical models by acoustic-electro analogy. The analytical model is presented to explore the physical properties of sound absorption and the influence of parameters, which has been validated by comparisons with the numerical model, and the experimental data is measured by an impedance tube. It is found that the main incident energy is lost by the inside hole, which is different from the conventional absorbers with surface MPP. Moreover, the side length of the internal honeycomb can adjust the resonant frequencies to achieve an absorber with the subwavelength. A SSHS is designed with a perfect absorption at 320 Hz whose thickness is 1/31 of the resonant frequency wavelength. The SHHS has excellent potential for noise control engineering applications.

A comparative study on drillability of Inconel 625 alloy fabricated by wire arc additive manufacturing

In recent years, the cost-effective wire arc additive manufacturing (WAAM) method is increasingly replacing traditional production methods for Ni-based superalloys. However, the effect of high heat input and elemental segregation in the WAAM method on machinability has not yet been adequately investigated. For this purpose, drilling of wrought and WAAM Inconel 625 samples with thermal (i.e., die-sinking micro-EDM and micro-EDM) and mechanical drilling techniques (i.e., orbital and conventional drilling) was investigated in this study. It was observed that thermal drilling methods formed a white layer with a thickness of 20-25 μm and 35-50 μm in the cross-section of wrought and WAAM specimens, respectively, while no white layer was formed in the mechanical methods. The average surface roughness of the inside hole, Ra, obtained in the conventional drilling process has improved by 46.15 %, 94.62 %, and 92.82 %, compared to the orbital, die-sinking, and micro-EDM methods, respectively. Because the drill cutting form and helix angle used in this method facilitated chip evacuation. The best surface roughness was obtained respectively by conventional (0.27–029), orbital (0.51–0.53), die-sinking (4.54–5.88), and micro-EDM drilling (3.54–4.25) methods. In addition, a larger kerf angle is obtained in the WAAM sample compared to the wrought one due to higher residual stress and higher dislocation density in the WAAM alloy. On the other hand, the higher hardness value of WAAM samples provided better surface quality in mechanical drilling methods than wrought material. An increase in surface hardness values up to 25 μm from the surface was detected due to the recast layer formed in thermal drilling methods and the strain hardening occurring on the surface in mechanical drilling methods.

Fall streak hole observed in the Midlands, UK

WeatherVolume 77, Issue 3 p. E2-E2 Inside Cover Photograph Fall streak hole observed in the Midlands, UK First published: 10 March 2022 https://doi.org/10.1002/wea.4167Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume77, Issue3Special Issue: The January 2022 eruption of Hunga Tonga-Hunga Ha'apai March 2022Pages E2-E2 RelatedInformation

EXPERIMENTAL STUDY OF MICRO SILICA BEHAVIOR AND ITS EFFECT ON IRAQI CEMENT PERFORMANCE BY USING X-RAY FLUORESCENCE ANALYSIS

The cement slurry is a mixture of cement, water and additives which is established at the surface for injecting inside hole. The compressive strength is considered the most important properties of slurry for testing the slurry reliability and is the ability of slurry to resist deformation and formation fluids. Compressive strength is governed by the sort of raw materials that include additives, cement structure, and exposure circumstances. In this work, we use micro silica like pozzolanic materials. Silica fume is very fine noncrystalline substantial. Silica fume can be utilized like material for supplemental cementations for increasing the compressive strength and durability of cement. Silica fume has very fine particles size less than 1 micron and by an average of about 0.1 microns, about 100 times slighter than particles of cement. We are adding 0%, 5%, 10%, 15%, 20% and 25% micro silica by wt. of cement. The results showed that adding micro silica enhance the performance of Iraqi cement but also leads to a slight decrease in thickening time. To avoid this problem, super plasticizer is used to make the process of cement pumping more easily, in other words, increase thickening time and increase compressive strength. The experimental work showed that adding micro silica leads to reduce free water and this property is very important through horizontal drilling. X-ray fluorescence technique delivers beneficial elemental information about the chemical structure of Iraqi cement to help us use it without causing damage through the cementing job. In this paper, some outlines of the XRF device and its main applications are presented. By using X-ray fluorescence analysis, we detect the problem of Iraqi cement and solve it in this paper to use it at cementing jobs in the Iraqi field instead of using imported cement.

Improving the Performance of EDM through Relief-Angled Tool Designs

Among the family of carbides, tungsten carbide (WC) and its variants have extensive use in numerous applications including cutting tools, dies, and many wear resistant parts. Such applications need machining of WC, which is famously considered as challenging due to high tool wear mainly in traditional machining. Sinking electric discharge machining (EDM) can be considered as a suitable alternate but the low machining rate of EDM, with conventional tool design, poses limitations. In this research, the conventional tool design is modified by providing relief angles to the tool electrodes. The relief-angled tool electrodes are first time introduced in this research to machine through holes. The role of the relief angle during EDM has been investigated in terms of six response characteristics, i.e., machining time, hole taper angle, radial overcut at the hole entrance, radial undercut at the hole exit, longitudinal tool wear, and roughness of inside hole surfaces. The performance of the relief-angled electrodes is found to be significantly better than the performance of conventional cylindrical tool. In addition to improvements in other responses, a 49% reduction in the machining time has been realized by the use of relief-angled electrode indicating a worthwhile contribution in the field of electric discharge machining.

Effects of machining conditions on the hole wall delamination in both conventional and ultrasonic-assisted CFRP drilling

The need of carbon fiber–reinforced plastics (CFRP) has been driven by the increasingly wide applications in many industrials including sports, transportation, and energy. However, until now, the poor machinability of CFRP can be still considered the key problem and the most urgent machining-induced issue can be the delamination damage in the drilling process. Although many efforts have been paid to investigate this topic, most of them investigated the delamination at either the hole entrance and the exit. Very few of these studies focused on the internal delamination defects on the hole wall, although these internal defects can be as important as the entrance and exit defects. To fill this gap, this paper investigated the condition effects (feed rate, spindle speed, ultrasonic vibration of drills, and the workpiece support strategy) on the delamination in CFRP drilling, with the special focus on the internal delamination damage on the inside hole walls. Based on both the experimental and theoretical analysis, the effectiveness of the back supports and the variable feed rates was investigated as well. Considering few published studies reported the delamination on the hole wall, the key findings in this paper are expected to be meaningful to deepen the understanding of CFRP drilling and helpful to provide some industrial guidance.

CFD Analysis of Internal Flow inside Multi Hole Diesel Nozzle

CFD Analysis of Internal Flow inside Multi Hole Diesel Nozzle

The Selenium-Sulfide Infiltrated Carbon Cathodes for Lithium-Sulfur Batteries: Effects of Carbon Framework Structure and Dopants on the Electrochemical Performances

The Selenium-Sulfur/Carbon(Se-S/C) composites containing Se, which has much higher electrical conductivity (10-3 S cm-1) than S (5*10-28 S cm-1), have been suggested as a new cathode material instead of S/C composites [1-3]. Specifically, SeS2/C composites delivers competitive volumetric capacity (4026 mAh cm-3) compared to sulfur (3296 mAh cm-3) due to larger density of Se (4.82 g cm-3). Despite of these advantages of the Se-S/C, the material could not be used practically due to a severe capacity decay, which is induced by Shuttle Effect in the Se-S/C composites as well as in the S/C composites. It has been considered that one of the good solutions is that the Se-S are confined effectively within the carbon framework during cycling [1-4]. Zhen et al [2]. introduced CMK/SeS2@PDA cathode material, which utilized the well-aligned mesoporous carbon and the conductive polymer coating to confine soluble intermediates physically, but it showed only 55 % of capacity retention after 500 cycles at 0.2 A g-1. Even though it exhibited better long-term cyclic performance in comparison with previously reported Se-S/C works, its capacity retention was still low and the extra coating process was also ineffective way to confine Se-S into pores [2]. In this study, we aimed to demonstrate the effects of the structure and dopants of the carbon framework on the electrochemical performances of the Se-S/C cathode. We prepared the SeS2/C composites by a facile melt-diffusion and an evaporation method employing 4 different carbon frameworks; (i) mesoporous carbon(OMC), (ii) nitrogen-doped ordered mesoporous carbon(NOMC), (iii) sulfur-doped ordered mesoporous carbon(SOMC), and (iv) ketjen black 600JD (KB600, commercial carbon). When preparing the SeS2/C composites, we intended that the SeS2 was partially filled on the carbon frameworks by making an inside hole of SeS2 inside pores of carbon framework, as shown in Fig. 1-2. We believed that it would be beneficial to suppressing volume expansion of chalcogen materials and utilization of the active materials. From the half-cell tests of four SeS2/C cathodes (SeS2/OMC, SeS2/NOMC, SeS2/SOMC, and SeS2/KB600) (Fig.3), the SeS2/KB600 showed the highest initial capacity due to its largest surface area that provides sufficient electrochemical reaction sites. However, it exhibited a poor cyclic stability due to the continuous dissolution of lithium polysulfides and polyselenides, originated from relatively large mean pore diameter (8.67 nm >) that is not suitable to trap the Se and S physically. Meanwhile, the SeS2 in the 3 types of ordered mesoporous carbons (OMC, NOMC, and SOMC), which have a large length to pore diameter ratio (L/D), delivered better rate-capability than the spherical KB600 (Fig. 3a). It implies that a long diffusion path for Li ions and partially filled SeS2 in the ordered mesoporous carbons are favorable to ion transportation inside pores [4]. Among all the SeS2/C cathodes, SeS2/NOMC exhibited the best electrochemical performance; nearly 99.99 % coulombic efficiency (no capacity fading during 500 cycles) presumably due to its N dopant that contribute to chemical adsorption of the soluble intermediates (Fig. 3b, 4).

Investigation of Grinding Fluid for Prevention of Chip Adhesion in Miniature Drilling of Glass Plate Using Electroplated Diamond Tool

In the hole drilling process, produced chip cannot be released from the inside hole which leads to broken glass plate due to the adhered chip on tool. Chip discharge method was announced by many researchers. However, the method using the tool-only with drilling command is rarely seen. In this laboratory, we have developed a tool in order to discharge chip. The developed tool is capable in preventing chip adhesion and producing high quality and efficient hole drilling process. The developed tool has several hundred times longer tool life than a conventional tool. However, the amount of adhered chips on cutting tool increase as the number of hole drilling process increases. The chip adhesion condition is different according to the kind of grinding fluid. Adhesion of chips on tool can be related to the properties of grinding fluid. Thus, in this study, the types of grinding fluid used during the hole drilling process were investigated to determine the state of chip adhesion. Three types of grinding fluid used are Emulsion, Soluble and Solution and all of them include surfactant which is considered to have an effect on prevention of chip adhesion. The main conclusions obtained in this study are as follows. Chip adhesion state was investigated after drilling process and it was found that instead of grinding fluid properties, surfactant also has significant effect on chip adhesion on tool by absorbing the adhered chip from the tool. The results showed that grinding fluid with long-chain surfactant has small amount of chip adhesion whereas grinding fluid with short-chain surfactant has large amount of chip adhesion. Therefore, it can be concluded that grinding fluid with long-chain surfactant is capable in preventing chip adhesion during hole drilling process.

Numerical simulations of detecting perforated slim hole length in formation with an acoustic method

Water-jet deep penetrating perforation, which utilizes high pressure water-jet to penetrate reservoirs, is a new well interference technology for increasing deliverability. The length of water-jet hole is a key parameter for evaluating water-jet effect. We simulated and compared acoustic fields both inside and outside water-jet hole in different conditions with the time-domain finite difference method. The water-jet hole in the modeling is 3 cm in diameter and 10 m in length. Based on the simulation results, we analyzed the feasibility to detect the length of water-jet hole mainly by adopting low frequency source. Simulation results show that the high frequency source can excite multiple waves inside the water-jet hole, including refraction P and S waves, pseudo-Rayleigh waves, and Stoneley waves. Thus, the signals received in borehole are complex. On the contrary, the low frequency source excites few modes inside the water-jet hole. Specifically, there are only Stoneley waves when the source frequency is...

The impact of defects on the capacity of timber joints with glued-in rods

Glued-in rods are an increasingly used technical solution for numerous structural applications in timber engineering, and demonstrate the potential of adhesively bonded connections. During the insertion process the adhesive fills a very narrow gap over significant anchorage contact area, raising concerns that manufacturing defects may impact the structural performance of the bonded joint, namely the possible lack of adhesion resulting from inadequate preparation of the joint on site. Previous studies on the effect of bonding defects on the capacity of bonded joints identified a nuanced relationship that depends on the ductility of the adhesive.This paper presents experimental evidence that sheds light on the relationship between defects and capacity of glued timber joints. Joints composed of softwood glulam members and mild steel glued-in threaded rods were manufactured with two types of defects likely to be encountered on-site: i) rods placed at an angle inside drill hole instead of aligned with the joint axis, and ii) rod placed against the side of the drill hole instead of fully centered. To establish performance benchmarks a first phase studied the influence of the anchorage length and the rod diameter using three different adhesives. The effect of these defects on joint capacity was investigated with three different adhesives in combination with three different rod anchorage lengths. The investigations demonstrated that joints with sufficient rod anchorage (herein 10 times the rod diameter) do not exhibit a statistically significant loss of capacity, if compared to defect free joints. These results can contribute towards better understanding of the influence that the studied parameters have on the performance on timber joints with glued-in rods, as well as to translate this information to promote the development of further applications.

Exploratory and anxiety potentials of aqueous extract of Phragmanthera capitata

Aim: To evaluate the exploratory and anxiety potentials of aqueous extract of Phragmanthera capitata (AEPC) in Wistar rats using hole-board paradigm. Materials and Methods: Healthy rats were randomized into 5 groups. Group I (control) received 10 ml/kg saline, Group II (standard) received 0.2 mg/kg Diazepam, Groups III-V (tests) received 100, 200 and 400 mg/kg AEPC respectively. Changes in the emotional state of rats were assessed through changes in exploratory activities. Hole exploration consisted of point-sniff, circular-sniff and central sniff while inside hole exploration consisted of staticdip, rapid-dip and active-dip. Latency of the first head-dipping, number and duration of rearing, number of crossing from one compartment to another were also evaluated. Data were analyzed using analysis of variance (ANOVA) with the test used as post hoc. Results: In head dipping, there was a significant increase for 200 and 400 mg/kg AEPC as compared to control. In sniffing, 200 and 400 mg/kg AEPC also showed significant increase in point sniffing and central sniffing respectively. Rearing, duration and mean number of crossing were significantly decreased by 400 mg/kg AEPC. Latency of the first headdipping was significantly decreased by 400 mg/kg AEPC. Conclusion: The results suggest that Phragmanthera capitata has bioactive molecules that act in the central nervous system to lower anxiety.

Perturbation solution of two arbitrarily-shaped holes in a piezoelectric solid

This paper presents a perturbation solution to a two-dimensional problem of two arbitrarily shaped holes within an infinite piezoelectric solid subjected to uniform mechanical and electric loads at infinity. Of particular interest are the stress field and electric field around hole with relation to the distance between the two holes. The shape of each hole is characterized by a truncated mapping which can be regarded as that for an elliptical hole with a perturbation. By using the perturbation method and Faber series, both the complex potentials of the piezoelectric solid and the electric fields inside holes are expressed in a series form with unknown coefficients to be determined by Fourier expansion method. Detailed numerical results are shown for oval, elliptical, triangular and square holes. A basic conclusion is that the hoop stress and electric field strength nearby the point of maximum curvature on the hole׳s boundary increase rapidly with decreasing distance between the point of maximum curvature and the other hole. On the other hand, it is shown that the electric field inside non-elliptical hole is always non-uniform regardless of the distance between the two holes, while that inside elliptical hole tends to be uniform with increasing distance between the two holes. Additionally, if the distance between the two holes is more than four times the hole size, the interaction between the two holes is ignorable and the problem of two holes can be divided into two separate problems of only a single hole.

2-D Image of Eddy-Current Testing and Dependence of Shape for Notch inside of Narrow Hole by Needle-Type Probe

2-D Image of Eddy-Current Testing and Dependence of Shape for Notch inside of Narrow Hole by Needle-Type Probe

Thermodynamic theory of controlled formation of strained quantum dots on hole-patterned substrates

We have established a thermodynamic model to address the strained quantum dots (QDs) formation on hole-patterned substrates. Based on the investigation on the morphologies at the initial stages of thin wetting layer growth, we found that the thickness of wetting layer inside of hole is larger than that on the terrace between holes due to the concave surface during the initial layer-by-layer growth process. The increased thickness on the inside of hole results in the different formation sites for different growth temperatures, i.e., QDs form on the inside of hole at low temperature, and QDs form on the terrace between holes at high temperature.

In situ STM observation during InAs growth in nano holes at 300 °C

We have successfully confirmed that In atoms were favored to congregate inside hole structures, during In and As4 irradiations, by a STMBE system which was a scanning tunneling microscope located inside a molecular beam epitaxy growth chamber. After forming 1.5 monolayer of InAs wetting layer (WL) on a GaAs(001) surface, we applied voltage at a particular site on the WL during As4 irradiation at 300°C, creating hole structures (widths: 33–66.1nm, depths: 4.9–9.7nm). With the In and As4 irradiations, spontaneously, In atoms on the WL were congregated inside the holes, decreasing the volume of the hole structures. It was found that InAs growth rates inside the hole structures were 23.1–217 times larger than that at the WL growth region near the holes.

Buoyancy-induced squeezing of a deformable drop through an axisymmetric ring constriction

Axisymmetric boundary-integral (BI) simulations were made for buoyancy-induced squeezing of a deformable drop through a ring constriction. The algorithm uses the Hebeker representation for the solid-particle contribution. A high-order, near-singularity subtraction technique is essential for near-critical squeezing. The drop velocity and minimum drop-solid spacing were determined for different ring and hole sizes, viscosity ratios, and Bond numbers, where the latter is a dimensionless ratio of gravitational to interfacial forces. The drop velocity decelerates typically 100-fold or more, and the drop-solid spacing reduces to typically 0.1%–1% of the nondeformed drop radius as the drop passes through the constriction. The critical Bond number (below which trapping occurs) was determined for different conditions. For supercritical conditions, the nondimensional time required for the drop to pass through the ring increases for a fixed drop-to-hole size with increasing viscosity ratio and decreasing Bond number, but it has a nonmonotonic dependence on the ratio of the radii of the drop and ring cross section. Numerical results indicate that the square of the drop squeezing time is inversely proportional to the Bond number minus the critical Bond number for near-critical squeezing. The critical Bond number, determined from dynamic BI calculations, compares favorably to that obtained precisely from a static algorithm. The static algorithm uses the Young–Laplace equation to calculate the pendant and sessile portions of the drop interface coupled through the conditions of global pressure continuity and total drop volume conservation. Over a limited parameter space, the critical Bond number increases almost linearly with the drop-to-hole ratio and is a weak function of the ratio of the ring cross-sectional radius to the hole radius. Another dynamic phenomenon, in addition to drop squeezing, is a drop “dripping” around the outer edge of the ring constriction, and a critical Bond number maximum versus the drop-to-total ring radius ratio is caused by the transitions from squeezing to dripping for the loss of a drop steady state on a constriction. The initial stages of drop dripping are numerically simulated using a boundary-integral method for slightly supercritical Bond numbers. For very large ratios of the drop-to-hole radii, however, a sharp maximum in the critical Bond number is reached, as there is a transition from the drop passing through the inside hole to dripping over the outside edge of the ring for Bond numbers above the critical line. Drop squeezing and trapping mechanisms are also observed experimentally, and the measured critical Bond numbers and trapped drop shapes compare favorably to theoretical calculations from the Young–Laplace algorithm.