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This paper presents the results of a numerical study of the effects of swirling flow in coolant jets on film cooling performance. Some combined-hole designs with swirling coolant flow entering the delivery hole are proposed and analyzed. Adiabatic film cooling effectiveness values for cases with various blowing ratios are compared. Detailed flow structures and underlying mechanisms are discussed. The results show that film cooling effectiveness is improved with jet swirl at high blowing ratios, and that swirl strength has significant influence on film cooling performance. Combined-hole designs can further improve film cooling performance using swirling jets due to mixing of coolant flows and interaction of vortices. The largest improvements of area-averaged film cooling effectiveness for a single-hole swirl case and a combined-hole swirl case over corresponding non-swirling case results are 157% and 173%, respectively.

We present an experimental study of the coherence properties of a single heavy-hole spin qubit formed in one quantum dot of a gated GaAs/AlGaAs double quantum dot device. We use a modified spin-readout latching technique in which the second quantum dot serves both as an auxiliary element for a fast spin-dependent readout within a 200 ns time window and as a register for storing the spin-state information. To manipulate the single-spin qubit, we apply sequences of microwave bursts of various amplitudes and durations to make Rabi, Ramsey, Hahn-echo, and CPMG measurements. As a result of the qubit manipulation protocols combined with the latching spin readout, we determine and discuss the achieved qubit coherence times: T1, TRabi, T2*, and T2CPMG vs. microwave excitation amplitude, detuning, and additional relevant parameters.

The Miss stress, Max.principal strain and Magnitude displacement have important influence on the fatigue life of the Ni-based single crystal super-alloy turbine blades. This work investigated The Miss stress, Max.principal strain and Magnitude displacement of Ni-based single crystal super-alloy specimen with single hole along dangerous path under different working conditions by Abacus. The results show that the initial crack length and loading stresses are larger, the crack growth on the specimen is faster, and then, the fatigue life is the shorter. Moreover, for the different stress ratios, smaller stress ratio can lead to lower fatigue life. The result is significant to design turbine of Ni-based single crystal super-alloy of high accuracy, high reliability and high strength.

A method of predicting the fatigue life under multiaxis loads based on the Paris law and EIFS was proposed. And the fatigue life under different loading stress and stress ratio were investigated. The results show that when the loading stress increased from 450~800 MPa, the fatigue life decreased from 6762379 to 10056, as well as when the stress ratio increased from 0.1~1, the fatigue life increased from 6762379 to 14932368. It was validated by test eventually. And the fatigue life model presented here agrees well with test results. It is significant to the prediction of turbine of Ni-based single crystal super-alloy material with filming hole.

This paper presents an experimental investigation on the injection characteristics of a single hole at the leading edge of a flat plate immersed in mainstream air. The influence of the hole diameter, hole inclination angle , and pressure difference coefficients on the flow rate coefficient of an injection hole is investigated. For designing film cooled blades, it is necessary to predict the characterestics of the coolant flow rate from each injection hole. It is found that the maximum flow rate coefficient occurs at a hole inclination angle of 35o for different hole diameter and different pressure coefficient. Flow rate coefficient increase with increasing pressure coefficient.

In the present work, effects of nozzle hole size and rail pressure under non-evaporating spray condition are demonstrated. Three single hole injectors with the bore size of 0.101, 0.122, and 0.133 mm are experimented with injection pressures of 140, 45, and 38 MPa respectively to achieve similar injection rate profile. Diesel spray experiments implement Diffused Backlight Illumination Technique where diffused background is obtained for the High Speed Video camera imaging. Experimental results are then validated with computational and analytical studies. The CFD simulation requires the injection rate profile and spray cone angle as a primary input; thus, based on the High Speed Video Camera start of injection frame the 5 kHz Butterworth low-pass frequency filter is applied to the injection rate raw data. While, the spray cone angle is predicted using a simple model obtained from the relationship between the injection velocity, fluctuating velocity at the nozzle exit and total pressure loss factor of the injector. The experimental spray tip penetration of all three injectors is almost identical as the similar injection rate profile is adopted. Although, the mixture characteristics are better for 0.101 mm hole diameter since the smaller hole diameter with highest injection pressure depicts larger spray angle and better atomization. The computational study agrees with experiments qualitatively; however, the quantitative and qualitative agreements are seen in the analytical study.

Using polymethyl methacrylate (PMMA) as the test material, three-point bending tests were carried out on single hole and double hole specimens with prefabricated cracks at the bottom. The fracture ...

Numerous researches have focused on the physical behavior of an elastic material in the vicinity of a single hole under the assumption that the interaction effects arising from the introduction of multiple holes remain negligible if the holes are placed sufficiently far from each other. In an effort to understand hole interaction effects on heat conduction and thermal stress, we consider the case when two circular holes are embedded in an infinite elastic material and use complex variable methods together with numerical analysis to obtain solutions describing temperature and elastic fields in the vicinity of the two circular holes. The results indicate that the interaction effects on temperature distribution and stress strongly depend on the relative size of the two holes and the distance placed between them but not on the actual size of the holes.

Background Flexor digitorum profundus (FDP) avulsion injuries occur following forced hyperextension of the distal interphalangeal joint (DIPJ). Methods We highlight a case report of FDP avulsion injury fixed using a single hole of a plate in combination with a cortical screw to act as a washer. A search and discussion of the literature is included.

The effects of the hole size and perforated plate position on the propagation of flame and flow and pressure oscillation were explored in a constant volume combustion chamber (CVCB) with a single-hole perforated plate. Stoichiometric hydrogen-air mixture was used in the experiments, and the propagation of the flame and jet flow were recorded by high-speed schlieren photography. The results demonstrated that the flame velocity firstly increases and then decreases with the increasing hole size. With the hole size of 13 mm, the flame velocity, peak pressure, and pressure oscillation reached the maximum under the current experimental conditions. Moreover, the influence of the position of the perforated plate was investigated. It was found that the jet flow before the flame front is prominently distinct when the perforated plate is in positions A and B, resulting in an apparent difference in the flame shape behind the perforated plate, which means that the movement of the jet flow plays a leading role in the development of the flame. In Position B, the flame front overlapped with the jet flow and has the same shape. Besides, an interesting phenomenon was captured: with perforated plate in Position B, a secondary flame front was generated with higher flame tip velocity before the primary flame front under the effect of the flame-vortex interaction.

In the present work, experimental and numerical study has been performed to investigate the effects of a novel film-cooling design with shaped multi-holes on the film-cooling effectiveness over a flat plate. A single cylindrical hole with 11.1 mm diameter has been replaced by multi-holes (14 holes with 2.97 mm diameter) with elliptical and fan-shaped configurations. The exit area, length to diameter ratio (L/D = 4.0) and injection angle (35°) of multi-holes are selected identical to the single cylindrical hole. The multi-holes were machined with a fixed spacing pitch (33.3 mm) between the centers of two adjacent holes. The surface temperature of the test plate was measured by an infrared camera. The experimental studies were performed at blowing ratios of 0.5 and 2. The numerical results based on the steady RANS with realizable k–e turbulence model and enhanced wall treatment were capable to predict the influence of the shape of multi-hole configurations on overall adiabatic film-cooling effectiveness. The experimental and numerical results showed that replacing a single hole with a shaped multi-hole leads to a considerable increase in film-cooling effectiveness in both axial and lateral directions. According to the results at blowing ratio of 2.0, the elliptical and fan-shaped configurations provide a higher area-averaged film-cooling effectiveness by 75% and 248.2% in comparison with the single hole, respectively.

An experimental assessment has been made of the influence of electro-erosive modification modes for worn working surface of an cutter on the restoration of its cutting ability. The paper provides basic information on dental cutters. The provisions of the experimental research methodology are described, including a description of a device for modifying the worn surface of a dental cutter and a device for determining its cutting ability. Experimental data are presented and analyzed that reflect an effect on restoration of a cutting ability of a worn surface of a dental cutter, voltage of a storage capacitor and number of holes applied to it during its modification. Rational modes of modifying a worn-out surface of a dental mill that provide the greatest recovery of its cutting ability have been determined in the paper. It has been shown that with increasing voltage, the energy of the electric discharge acting on the treated surface increases, which leads to the formation of a single hole of a larger size on it, including metal flows along its edge that extend beyond the initial contour of the worn cutter teeth. These metal flows on the modified surface of the cutter play the role of peculiar cutting and deforming elements. It has been revealed that in the process of modifying the worn surface of the cutter, it is necessary to ensure that there is no overlap of the holes formed on it, i.e. the distance between the centers of adjacent holes should be greater than or equal to the size of metal deposits at their edges. In this case, the metal flows retain their original shape and have the highest height at these pulse parameters, which ensures a higher cutting ability of the modified cutter surface than when the holes are overlapped.

The low-cycle fatigue properties of the Ni-based superalloy K416B with single film cooling hole were investigated. The low-cycle fatigue tests were carried out using tension cycling under stress-controlled conditions (stress ratio R = 0.1) at room temperature. The fatigue limit lives of the perforated samples were determined by the lifting method. The fracture morphologies and microstructural evolution were examined. The results showed that the fatigue crack initiated from the film cooling hole. Furthermore, fracture paths and surface morphologies of the samples were influenced significantly by the stress level. The analysis of the microstructural evolution further indicated that the fatigue failure mechanisms of the samples with a film cooling hole depended on the stress level.

Single-hole (SH) injectors were compared with multi-hole (MH) injectors to reveal the differences in nozzle internal flow and spray propagation. The multi-phase flow inside the nozzles was numerica...

The direct prediction model for adiabatic film cooling effectiveness distribution and inverse prediction model for design parameters are studied in this article. Convolutional neural networks (CNNs) are trained on a set of simulated adiabatic film cooling effectiveness contours parameterized by blowing ratio, density ratio, mainstream turbulence intensity, injection angle, and compound angle. The direct model and the inverse model are able to approximate the data in the test set with plausible accuracy. The absolute error of spatial averaged effectiveness no larger than 0.03 could be obtained in the test set by a direct model with time consumption less than 1 ms for a single case. The inverse model is the first model of its kind, which accomplished the inverse mapping from contours to parameters. It has been demonstrated that the concatenation of inverse model with the pretrained direct model, which can be treated as a complex loss function, has preferable approximation performance compared with simple mean squared error (MSE) loss function in the training of the inverse model, thus confirming the necessity of adopting specialized modeling strategies for inverse problems.

Direct injection in internal combustion engines is often realized with a multi hole injector which forms a spray pattern consisting of multiple jets with a small distance between their origin. This leads to an interaction of adjacent spray jets. The spray characteristic is significantly influenced by this interaction, and can considerably change the fuel evaporation and with it the emission behavior with varying number of holes or hole nozzle geometry [8]. Experimental investigations, especially if a good optical access to a single jet is necessary, often needs to use a comparable injector with a reduced number of holes. In addition to that, 3D-CFD simulation models can also use a reduction of spray jet number for a partial consideration of fuel mixture to reduce the computing time. For these cases a determination of the correlation between spray formation and reduced nozzle holes is important. In this work the spray patterns of an original 6-hole gasoline DI-injector and, after closing of 5 holes, the resulting 1-hole injector were compared. The fuel mass flow through one hole can change due to a change of hydrodynamic effects inside the nozzle and leads to a correcting factor for the injecting time, to get comparable fuel mass flows. The penetration depth, droplet speed, size and spatial distribution were measured. Additional investigations of the influence of the fuel pressure and fuel temperature were carried out.

A screening trial with eight varieties of sapota against seed borer, Trymalitis margarias Meyrick under normal (10 × 10 m) and high density plantations (5 × 5 m) was carried out. The fruit damage due to seed borer revealed that Kalipatti (7.50%), DHS-2 (5.88%) and Cricket ball (5.55%) had higher infestation, while moderate damage noted in DHS-1 (3.42%) and PKM-1 (3.40%) during both the season. The fruit losses were lesser in PKM-4 (2.77%), PKM-3 (2.46%) and CO-3 (2.34%). The two year data indicated that there was no infestation differences in normal (4.38%) and high density spacing (3.95%) plantations, however the higher fruit damage was noted under normal spacing over high density plantation in individual years. The morphological characteristics like weight, colour and shape of fruit and seed along with number of seeds/fruit and weight loss in seed under different sapota varieties did not showed association with the infestation level of seed borer. However under normal and high density plantation, single hole as well as hole on lower half of fruits was observed cent per cent in fruits of tolerant varieties viz., PKM-1, PKM-4 and CO-3, while it was 60 -90% in other varieties.

Prediction and control of ground vibrations become essential as with the development of neighborhoods in the proximity of active mining operations or the need for new infrastructure in urban centers, both requiring the use of blasting. Novel ground vibration prediction models attempt to reproduce a whole vibration waveform from a blast and are based, in most cases, on the collection of vibrational information from a single blasthole. A single blasthole should have the same characteristics (geometry and weights of explosives) as the blastholes used in production shots. In some cases, the collection of the fundamental information (the signature) is straightforward. In more complex cases, the fundamental information from ground vibration data is collected from previous production shots. This study presents a novel methodology to assess the fundamental ground vibration information (the signature) using known information such as one event waveform (a production shot waveform) and the timing sequence used (the comb function) for the shot. The methodology is based on the analysis of group delay, a concept widely used in signal processing, and is modified here for the analysis of ground vibration waveforms. The methodology is developed using real data collected in coal and quarry mining operations, and at the end of this document, one case study with step-by-step calculations is presented to show the benefits of the methodology.

Layered rock masses with holes are common in nature. Their mechanical behavior plays an important role in the safety and stability of engineering structures. However, previous studies have concentrated on a single lithological layer, and few studies have reported on the mechanical behavior of layered rock masses with holes. Based on the concept of symmetry, uniaxial compression tests and numerical simulations were performed on rock-like specimens with three layers and a hole in the interlayer. The hole was in the center of the sample and was symmetrical up and down. The influence of the thickness and strength of the interlayer on the mechanical behavior and failure processes of the layered rock masses with holes was investigated. The results show that the peak strength and elastic modulus were associated with the thickness and strength of the interlayer. Three failure modes were observed in the specimens, which were not only related to the thickness and strength of the interlayer, but also affected by the presence of the hole. When the thickness of the interlayer is small, mainly a single failure mode was observed (tensile failure or shear failure). However, when the interlayer was thick, the failure mode was tension-shear mixed failure. The failure mechanism of the specimens was primarily crack propagation at the edge of the hole. These research results can provide a basis for site selection, and the design of surrounding rock protection and support parameters, and thus have important practical significance for improving surrounding rock stability and ensuring construction safety.

In this study, we explored the mask electrochemical machining parameters: electrolyte concentration, operating voltage, mask hole diameter, mask thickness and other processing parameter variability through the screen printing mask manufacturing method, and then used Taguchi method as the analysis tool. Use the controllable factor of the experimental parameters to explore the influence of the processing parameters on the undercut of a single hole and the uniformity of the array, so as to obtain the best combination of processing parameters of the experimental data. A red copper was used as the tool, and a 304 stainless steel sheet (0.1 mm) was used as the workpiece. The experimental results show that the processing appearance is round when using the forward flow mode and the machining shape is elliptical when the lateral flow mode is used. Therefore, the forward flow mode is selected for subsequent experiments. For single-hole undercut and the uniformity of array holes, the most influential experimental parameters are the diameter of mask holes and the thickness of mask, and a set of optimal parameters are obtained smoothly from the study. The combination of optimal parameter for the single-hole undercut experiment is A2B1C1D3, the undercut amount is 72 μm, and the combination of optimal parameter for the uniformity of array holes in experiment is A2B1C1D3, and the average deviation is 7 μm.

In a triple-hole system comprising a primary hole and two sister holes, when the sister holes are positioned slightly downstream of the main hole under steady flow conditions, their jets generate an anti-counter-rotating vortex pair. Vortex interactions between the jets increase the effectiveness of adiabatic film cooling. In this study, a series of large-eddy simulations were conducted to understand how pulsations in the main flow affect film cooling in a triple hole. To understand the effects of pulsations on film cooling performance is important for better cooling design of the gas turbine engines. The numerical simulations were carried out on a flat plate geometry with a triple cylindrical hole system at 35° injection angle. The pulsations were approximately sinusoidal, and their effect on film cooling was investigated at several frequencies (2, 16, and 32 Hz) and Strouhal numbers (Sr = 0.1005, 0.8043, and 1.6085) at an average blowing ratio of 0.5. The results for the triple-hole system were compared with those for a single hole for the same amount of cooling air and the same cross-sectional area of the holes. Increasing the Strouhal number of the main flow decreased η in both systems. However, at each Strouhal number, η was higher in the triple hole. Furthermore, the triple-hole system was found to be better for film cooling than a single-hole system for higher values of the pulsation Strouhal number. Contours of time-averaged film cooling effectiveness and dimensionless temperature, instantaneous film cooling effectiveness contours on a test plate, mean velocity magnitude contours in the hole, and Q-contours for the triple holes under the application of pulsations to the flow were investigated.

Loess cave dwellings are the most typical style of regional architecture in northwest China; now, there are still tens of millions of people living in them. The northwest is an earthquake-prone area, and cave dwellings have suffered a lot of damage in previous moderate and strong earthquakes, so their earthquake resistance has attracted people’s attention. At present, the seismic analysis of aboveground building structures is relatively mature, while the seismic analysis of loess cave dwellings is less researched. To study the seismic response of loess cave dwellings, a single-hole cliff-side loess cave dwelling located in Yangjialing revolution former sites of Yan’an City of northwest China was investigated and surveyed; the three-dimensional numerical model was established by MIDAS/GTS NX. Combining the historic earthquake damage investigation, dynamic time-history analysis of the single-hole loess cliff-side cave dwelling subject to four horizontal earthquake actions was conducted to determine the weak positions, failure characteristics, and the corresponding displacement and stress of the loess cave dwelling under earthquake load. The results show that the loess has an amplification effect on the seismic waves, the arch vault is a key factor to the stability of the loess cave dwellings, the cliff-side loess cave dwellings in an 8-degree area cannot be used to continue living, and the entrance to loess cave dwellings is the most dangerous place when the earthquake happens.

The high-drainage roadway construction face of the working face is used to pre-drill the borehole under the tunneling face, and the problem of poor water return in the hole is solved by grouting the surrounding rock cracks in the deep and shallow holes of the drill floor. The “two plugs and one note” sealing method was adopted to ensure that the sealing holes were tight and airtight; the water pipes were blown all the way in the hole, and the single hole, grouping and timed water blowing work targets were realized, and the drilling effect of the downhole drilling was improved. A set of efficient and rapid down-drilling and hole-dissipation management mode has been formed, which has achieved the goal of high-efficiency outburst of coal seams and technical and economic integration in areas with high ground pressure and serious safety and economic benefits.

In this chapter we see an application of the Functional Analytic Approach to a domain perturbation of a somewhat different nature: instead of a domain with a single shrinking hole we consider a domain that contains two holes that collide into one another while shrinking in size. We confine ourselves to a Dirichlet problem for the Laplace equation. Different boundary value problems can also be analyzed and some examples can be found in Dalla Riva and Musolino (Comm Partial Differ Equ 41(5):812–837, 2016; Math Methods Appl Sci 41(3):986–993, 2018). Yet as occurs for the single hole problem of Chapter 8, the Dirichlet problem presents certain interesting features related to the appearance of a logarithmic behavior in the two-dimensional case. For this reason we prefer to focus on this problem and investigate it thoroughly.