Vertical Holes Research Articles

Analytical Study Regarding the Seismic Response of a Moment-Resisting (MR) Reinforced Concrete (RC) Frame System with Reduced Cross Sections of the RC Beams

In the last few decades, a series of earthquakes were recorded which pointed out several deficiencies regarding the ductile seismic response of MR RC frame structures. Thus, the research problem centres around the failure mechanisms registered by the structures, which differ from the general notions of seismic response commonly found in current design standards and norms regarding seismic actions. In these conditions, in the present paper—by using comparative methods—the analytical validation of the solution of plastic hinge concentration and seismic energy dissipation in the marginal beam areas is proposed. Therefore, the RC beam sections were reduced (weakened) in the marginal areas which exhibit a plastic deformation potential, as well as in the corner areas of concrete slabs with vertical rectangular holes. The significant outcomes of this research imply the partial “guiding” of plastic hinges in the zones adjacent to beam ends. Furthermore, a reduction of both the negative effects of horizontal rigidization of the beams and the cracking and plastic deformation effects of beam-column frame joints was observed. With these technical implications, a complex mechanism of plastic deformation of MR RC frame models is registered in which all lateral elements (including RC columns) participate in the dissipation of seismic energy, without the occurrence of the “weak storey” mechanism for any of the analytical RC frame models. Furthermore, it is possible to observe the partial formation of the global plastic mechanism “Strong Columns—Weak Beams” (SCWB) for some of the structural models. Finally, the analytically studied innovative element regarding the improvement of the seismic response of pure MR RC frame structures is successfully validated.

An experimental study of the mechanical behaviour of squat shear walls built with precast concrete two-way hollow slabs

This paper proposes an innovative precast shear wall system built with precast concrete two-way hollow slabs (PCHS shear walls). In the joints of the precast panels of the PCHS shear walls, noncontact lap splices of rebars with vertical and horizontal holes are used to connect adjacent precast panels. These panels contribute to an automated assembly and facilitate pouring concrete in-situ. The mechanical behaviour of PCHS shear walls and the connection performance of vertical joints are examined through pseudo-static loading testing on one cast-in-situ concrete shear wall and four PCHS shear walls. Moreover, the influences of different parameters, including axial compression ratio, aspect ratio and the magnitude of horizontal distribution reinforcements, were analysed. It was found that the "strong bending and weak shear" requirement was achieved for all specimens. For the PCHS shear walls, the typical prominent diagonal cracks and brittle failure were prevented by the shear slippage at vertical joints and vertical cracks. And the vertical joint enabled the PCHS shear walls to exhibit stable load-bearing capacity with extensive deformations. In addition, the displacement ductility coefficient of all PCHS shear walls was over 5.0, and their ultimate drifts were over 1/100. The bearing capacity was improved with the increase of the axial compression ratio or with the decrease of the aspect ratio, but the deformation capacity was weakened.

Enhanced Vertical Hole Mobility through End-on Chain Orientation of Poly(3-hexylthiophene)-based Diblock Copolymers by Microphase Separation

Enhanced Vertical Hole Mobility through End-on Chain Orientation of Poly(3-hexylthiophene)-based Diblock Copolymers by Microphase Separation

Effect of etching solution concentration on preparation of Si holes by metal-assisted chemical etching

The effect of the etching solution concentration on the etching profile of vertical microscale holes formed on a Si(100) substrate by metal-assisted chemical etching (MacEtch) was investigated. MacEtch was performed at different solution concentration ratios (characterized by their molar ratio ), and the Au catalyst split above a certain concentration ratio. The Au–Si interface in the samples after MacEtch was observed using transmission electron microscopy, which revealed that there was a porous SiO x interlayer between the Au and Si, and that the SiO x layer became thinner as the concentration ratio increased. The interlayer almost disappeared under solution conditions when the catalyst was split. We propose two hypotheses for the mechanism of catalytic fracture during MacEtch: chemical fracture due to Si atoms diffusing into the grain boundaries of polycrystalline Au by Au–Si interdiffusion, and mechanical fracture due to stress on the catalyst caused by heterogeneous etching.

COMPARISON OF CEMENT AND SCREW FIXATION OF ORTHOPEDIC STRUCTURES

In dental prosthetics, every detail is important, because at this stage, not the aesthetic component is put in the first place, but the issue of engraftment of the implant. This will affect the further quality of life and the condition of the patient’s oral cavity. Therefore, in professional circles there are still discussions about which method of fixing the prosthesis is better - cementing or screw fixation, especially since both of them are widely used in dental surgery. This article will discuss the disadvantages and advantages of these methods.
 The connection of the implant, abutment and crown can be performed in two ways: fixation on cement - an abutment is fixed on the installed implant with a screw, on which the crown and dental cement are fixed. Screw fixation - the crown is connected to the abutment in advance, in the laboratory, then the finished structure is attached to the implant. For connection, a screw is used, which is inserted into a vertical hole penetrating the crown and abutment. After installing and fixing the crown, a hole remains on the chewing surface (the so-called screw shaft) - it is covered with a composite material.
 Of course, the screw design is mainly preferable due to the absence of excess cement. Excess cement is a good basis for biofilm formation. The larger the area of ​​the cement joint, the more bacteria appear. But the doctor is not able to use screw fixation in such situations: inconvenient entry into the implant shaft and there is no straight-line entry of the structure.
 Screw fixation has other advantages and disadvantages. The following advantages are distinguished: the crown can be easily removed; construction details fit exactly; there is no danger of cement getting into soft tissues; less work in the clinic and laboratory.
 So, when installing a denture, the orthopedist has two options for connecting the main parts of the structure (implant, abutment and crown) - cementing and screw fixation. In the first case, an abutment is fixed on the implant, and a cement-fixed crown is placed on top. During fixation, the screw crown is connected to the abutment in advance, and then the finished structure is attached to the implant itself. The method gets its name from a screw that is inserted into the crown and abutment and leaves a small hole in the crown. This "screw shaft" used to be a serious aesthetic problem, but now it is easily masked by the composite material.

Numerical analyses of post-fire beam-column assemblies with WUF-B connections against progressive collapse

This paper presents the progressive collapse experiment efforts in beam-column assemblies with WUF-B connections after fire exposure. A refined numerical simulation approach that considers the damage and failure for ductile metals was introduced to understand the structural response of the post-fire specimens. The established numerical model could effectively simulate the failure patterns, key fracture phenomenon, load–displacement response, as well as strain evolutions of the specimens. Subsequently, an abundance of parametric studies was performed based on the validated numerical approach to investigate the effects of variable configurations of WUF-B connections on the progressive collapse resistant performance of the beam-column assemblies. It was demonstrated that the vertical resistance and deformability of the post-fire assemblies could be obviously improved by enlarging the shear plate thickness. However, the bolt preload exerted little influence on the structural behaviors of the post-fire assemblies under column removal scenarios. For the assemblies with WUF-B connections, increasing the end distance between the inner bolt hole and the middle column flange (namely, parameters a) as well as decreasing the vertical bolt hole spacing (namely, parameters c) could effectively enhance the vertical resistance and deformability of the specimens. On account of the remaining unchanged crack propagation and force transfer path of the specimen, the horizontal bolt hole spacing (namely, parameters b) negligibly influenced the structural response of the specimens. In the anti-collapse design of the assemblies with WUF-B connections, it was suggested to appropriately increase the values of parameters a and b, but properly reduce these of parameter c on the premise of meeting the designed bolt configurations, which was more conducive to the formation and development of the catenary actions. Eventually, two typical reinforcement methods used for the post-fire assemblies were also numerically studied and compared in terms of the structural behaviors of strengthening specimens against progressive collapse.

Solid-State and Super Solidus Liquid Phase Sintering of 4340 Steel SLM Powders Shaped by Fused Filament Fabrication

4340 steel powders were processed with an additive manufacturing process using the FFF (Fused Filament Fabrication) technique. A composite filament was developed to print samples and study the effect of the bed and nozzle temperatures on its physical and microstructural properties. The printed samples were debinded and sintered by: Solid State (SS) at 1300 °C or SLPS (Supersolidus Liquid Phase Sintering) at 1420 °C. Metallography and scanning electron microscopy (SEM) identified the microstructure and phases. The hardness of the sintered samples was measured with the Vickers method. The SLPS process contributes to better densification and volume contraction; however, it promotes geometrical distortion of the samples compared to the SS samples. The microstructure of the sintered samples consists of ferrite situated in the original austenite grain and bainite. The sintering mechanism significantly influenced the hardness of the samples. Finally, a part was designed, printed, debinded, and sintered with the aim of studying the maximum inclination angle, the minimum vertical and horizontal holes, and the minimum vertical layer thickness, which can be obtained through the whole process.

New analytical solution and optimization of a thermocline solar energy storage using differential quadrature method and genetic programming

This paper aims to present an analytical correlation to investigate heat transfer characteristics in thermocline storage tanks based on numerical solution results. Thermocline tanks are used to store solar thermal energy to ensure the stable operation of the solar system. For the evaluation of thermocline energy storage, the mass and energy balance equations for the heat transfer fluid and the material used in the tank are extracted and simplified. The governing equations for two different configurations, including concrete blocks with vertical holes and concrete plates, are considered. Depending on the type of governing equations, an efficient numerical method called the Differential Quadrature Method (DQM) has been used to achieve an accurate solution in a short time, and the results have been validated in special cases based on previous research. Based on the numerical solution results, temperature distribution, thermodynamic efficiency, energy stored in charge and discharge mode, and thermocline tank capacity are calculated; and the effect of different variables on these parameters are evaluated. Based on the results, the effective variables are selected as the decision variable, and for different values of these variables, the evaluation parameters were calculated using DQM. Based on the results obtained from the DQM, a comprehensive database has been created and used as an input of genetic programming tools. Then the analytical correlations are presented to evaluate the evaluating parameters. Based on the prepared analytical correlations, different multi-objective optimization has been performed to maximize the stored energy (charge/discharge mode), thermodynamic efficiency, and power; and minimization of costs.

Gas Seepage Model and Experiment Based on Bedding Effect of Fractured Coal Body

Gas drainage is of great significance for the efficient and safe mining in coal mine, in which the coal seam layer bedding has a great influence on it. For obtaining gas permeability characteristics of coal body with the parallel and vertical bedding in fractured coal under the action of stress loading and unloading, experimental research was carried out employing a three-stress-axis simulation device. Experimental results showed that in the stress loading process, the permeability decreased with increasing effective stress; the decrement was initially rapid albeit it slowed later. With the increase of effective stress, the coal sample underwent three stages, namely, crack compaction, elastic deformation, and plastic deformation. In the stress unloading process, the permeability of coal samples increased with decreasing of effective stress, and the increasing trend of permeability was consistent. The degree of fracture compaction of the parallel bedding coal samples after compression was much higher than that of vertical bedding. In the stress-relieved coal seam, gas drainage boreholes should be arranged vertically to the bedding fissure to maximise the gas drainage effect. A group of parallel and vertical bedding gas drainage holes were arranged in the test mine to investigate the drainage effect. Field engineering application also showed that the drilling direction should be perpendicular to the bedding direction as far as possible, so as to improve the gas drainage effect. The research results can provide a reference for the gas drainage borehole layout, thus maximising the gas extraction efficiency and ensuring the sustainability of mine safety production.

Deep Etching of Silicon Based on Metal-Assisted Chemical Etching.

A deep etching method for silicon “micro”structures was successfully developed. This wet etching process is based on metal-assisted chemical etching (MACE), which was previously mainly utilized to etch the features that have lateral dimensions of “nanometers.” In this novel MACE, the critical improvement was to promote the “out-of-plane” mass transfer at the metal/Si interface with an ultrathin metal film. This enabled us to etch micrometer-wide holes, which was previously challenging due to the mass transport limitation. In addition, it was found that when ethanol was used as a solvent instead of water, the formation of porous defects was suppressed. Under the optimized etch conditions, deep (>200 μm) and vertical (>88°) holes could be carved out at a fast etch rate (>0.4 μm/min). This novel deep MACE will find utility in applications such as microelectromechanical systems (MEMS) devices or biosensors.

Segmentation Method for Modeling Heterogeneous Components to Suppress Broadband Simultaneous Switching Noise on a Multilayer Structure

Due to the rapid development of semiconductor manufacturing processes and 5G mobile system design, the need for high-speed digital electronic circuit miniaturization, high operating frequency, and high-speed transmission of data continues to increase. Electronic components are becoming smaller with faster operating speed. Fabricating a complete electronic circuit system with components from different manufacturers is likely to lead to unpredictable electromagnetic interference, signal integrity, power integrity, and other issues. Therefore, electromagnetic compatibility has become a key topic in the design of electronic circuits. We present a modeling approach that can be used to build the stopband and passband in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> -shape and the electromagnetic band gap (EBG) individually. In the model, the printed circuit board (PCB) is divided into five segments of different sizes, each of which has separate rectangular power and ground planes. Through the mushroom-type EBG, these structures are connected as part of a vertical blind hole; that is, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> -shaped power bus comprises a rectangular resonant cavity and transmission line. The proposed modeling method is proven to have accurate simulation, and it can be applied to complicated broadband structure for integrating the whole derivation process into computer programs. The proposed titanic broadband suppression structure can better suppress simultaneous switching noise (SSN) coupling ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\le -30$ </tex-math></inline-formula> dB) within the range of 5 MHz–40 GHz.

Vertical hole transport through unipolar InGaN quantum wells and double heterostructures

We report unipolar hole transport through unintentionally doped (UID) c-plane Ga-polar InGaN heterostructures to investigate the impact of alloy disorder on vertical transport. Simulations and experimental investigations were conducted on unipolar InGaN double heterostructures (DHs) and quantum well (QW) test structures by varying thicknesses and the number of QWs. The structures were simulated using one-dimensional (1D) and three-dimensional (3D) algorithms, incorporating the effects of random alloy disorder in the 3D model using the newly developed Localization Landscape theory. The electrical polarization discontinuity between GaN and InGaN results in a significant barrier for vertical carrier transport. Band-diagram and current density-voltage simulations indicate asymmetric polarization barriers to the vertical hole transport for the InGaN DHs. For the QW structures, however, the simulations indicate a symmetric barrier to the hole transport in forward and reverse bias. In the case of the InGaN DH layers, the 3D simulation results indicate a smaller barrier to hole transport compared to 1D simulations. For QW simulations, the barriers were found to be the same in both 1D and 3D simulations. The simulation results are experimentally verified using unipolar p-type vertical transport structures, enabled by n-to-p tunnel junctions to facilitate the current spreading within the bulk material for the mesa structures grown by ammonia-molecular beam epitaxy. The results indicate that increasing the UID ${\mathrm{In}}_{0.1}{\mathrm{Ga}}_{0.9}\mathrm{N}$ DH layer thickness from 15 to 30 nm increases the forward bias voltage drop (\ensuremath{\sim}2 V at $500\phantom{\rule{0.16em}{0ex}}\mathrm{A}/\mathrm{c}{\mathrm{m}}^{2}$) more than the reverse bias voltage drop (\ensuremath{\sim}0.2 V at $500\phantom{\rule{0.16em}{0ex}}\mathrm{A}/\mathrm{c}{\mathrm{m}}^{2}$). For the QW structures, increasing the number of QWs from one to three increases the voltage penalty similarly in forward and reverse directions (\ensuremath{\sim}0.25 V per QW at $500\phantom{\rule{0.16em}{0ex}}\mathrm{A}/\mathrm{c}{\mathrm{m}}^{2}$). The results are beneficial in understanding the impact of alloy disorder on the transport properties of the III-nitride heterostructures.

Cooling Performance of the Endwall Vertical Hole Considering the Interaction between Cooling Jet and Leading-Edge Horseshoe Vortex

Cooling Performance of the Endwall Vertical Hole Considering the Interaction between Cooling Jet and Leading-Edge Horseshoe Vortex

Short-period InAsSb-based strained layer superlattices for high quantum efficiency long-wave infrared detectors

Infrared detector barrier heterostructures with strained layer superlattice (SLS) absorbers with different periods were compared. The first was a reference using a conventional barrier heterostructure with a low temperature energy gap corresponding to a wavelength of 10 μm in a 2-μm-thick undoped absorber using a 10.9 nm period with InAs/InAsSb0.36 compositions grown directly on a GaSb substrate. The second structure, in contrast, used a significantly shorter 4.3 nm period absorber with InAsSb0.3/InAsSb0.55 compositions, similar energy gap, and absorber thickness, which were grown on a 6.2 Å lattice constant GaIn0.3Sb virtual substrate on GaSb. It was found that in the short period SLS, the vertical hole mobility and minority carrier lifetime in the temperature range of 80–150 K were a factor on 2–3 greater than in the reference structure. The improvement of the vertical hole mobility was attributed to the effect of hole delocalization. The latter results in an increase in the optical absorption coefficient and the quantum efficiency.

Research on Roof Structure and Determination of Working Resistance of Shallow Buried Single Key Stratum Based on Grid Drillhole Field Method

Abstract The roof structure of the stope is the core of revealing the weighting mechanism and determining the working resistance of support. The Shenfu Dongsheng coal field of China has abundant reserves of shallow coal seam. The phenomena of strong ground pressure and step subsidence caused by the mining of shallow buried single key stratum (SBSKS) poses a serious threat to the fragile environment. Revealing the shape and movement process of roof structure of SBSKS is the primary prerequisite for ensuring safe mining of working face. Firstly, the field measurement technology of the space grid-like drill field was developed to construct vertical holes and incline holes in the auxiliary headgate gateway and tailgate airway ahead of the working face and to obtain the measured data of the broken position and vertical displacement of the roof by the drilling peep and multipoint displacement. Secondly, the key parameters of the stope roof were analyzed by the grid drillhole filed method, for example, the inclined roof break angle, the rotation angle, the thickness of equivalent immediate roof (EIR), and the roof structure-articulated level and shape. Then, we combined with the mining face comparison of compression laws revealing the time and space relationship between the movement of the roof structure and the roof weighting, and three more dangerous states of the roof were determined. Finally, the roof structure of SBSKS is moved upward through the field research on the 22201 working face, the “high step rock beam” structure and the advanced breaking position of the roof are obtained, and the calculation equation of the support resistance in large mining height face is given. The research results provide scientific guidance for the safety of SBSKS coal seam and provide technical support for green mining in ecologically fragile mining areas.

A method to collect representative samples from water-driven percussion drilling techniques: examples from RoXplorer® coiled tubing drill rig

Water-driven percussion drilling techniques, such as that used by the RoXplorer® coiled tubing drill rig, return a rock sample as cuttings that are carried to the surface by the circulating drilling fluid. This drilling technique does not deliver a core sample. In order for the RoXplorer® to be effective as a mineral-exploration drill rig, it is critical to develop robust, representative and repeatable sampling techniques for the rock cuttings and to establish with confidence the depth interval from which the sample was derived. The RoXplorer® produces more than 7 kg/m of cuttings every few minutes (rate of penetration dependent) that are carried to the surface by the drilling fluid with a fluid return rate of 80–150 L/min. The cuttings, which range in size from <10 µm to 5 mm, require extraction from the drilling fluid and preparation prior to analysis. Subsampling of the fluid/cuttings stream can reduce the sample size to allow easier processing. A modified static cone splitter and ancillary flow-control system were designed and tested during field deployment of the RoXplorer® drill rig in South Australia in February 2017. We drilled a vertical hole with RoXplorer® starting 10 m to the northeast of an existing vertical diamond drill hole with well-characterised, shallow-dipping sedimentary and volcanic units. This allows comparison of drilling performance and sample quality against industry-standard drilling and sampling techniques. The performance of the splitter to take a representative continuous 1/8th subsample of drilling fluid and cuttings by volume was assessed based on its ability to resolve a 1 m interval of low-grade Cu mineralisation (0.74–1.03 wt% Cu) at 398 m that was detected in the reference diamond drill hole. The coiled tubing samples produced an equivalent and unbiased (chemistry and particle-size distribution) subsample, with sub-metre depth accuracy and comparable signal magnitude of the mineralisation at 398 m as detected in the diamond core. KEY POINTS Samples from the RoXplorer® drilling system were benchmarked against a twin diamond core hole that intersected a narrow band of copper mineralisation at 398 m depth A representative subsample was achieved through taking a split of cuttings as a slurry prior to dewatering Samples collected over key stratigraphic boundaries, including the narrow band of mineralisation, were accurately depth-constrained and had minimal carryover or mixing of cuttings when compared with the twin diamond core hole

Experimental identification and prioritization of design and process parameters on hole fill in mini wave soldering

Mini wave soldering is a common method for soldering through-hole components on printed circuit boards (PCB). With PCB design becoming increasingly complex and copper layer thickness rising, the vertical hole fill of through-hole solder joints becomes a serious problem during manufacturing. At the same time, the process window is limited by limited material heat resistance of the PCB and the through-hole components. Especially critical is latent damage inside the PCB and the through-hole component which must not exceed its specific maximum core temperature because this would compromise reliability over lifetime. The choice of soldering parameters is critical to reaching sufficient vertical fill to achieve a reliable connection according to IPC-A-610. The dedicated description of the interaction between PCB design and vertical fill has the potential to considerably improve the understanding of the basics of design for manufacturing (DfM). In this paper, the essential process parameters of the selective wave soldering process are examined by design of experiment (DoE) with respect to hole fill, which determines mechanical and thermal reliability as well as current carrying capacity. The results show the individual effects of the copper layer design parameters including layer count, layer thickness, hole copper plating attachment and solder alloy on vertical hole fill, in combination with the solder process parameters. The copper layer design parameters, solder bath temperature and preheating temperatures show the strongest effects. The soldering time has the lowest impact within the tested process parameters. For a given solder joint with its defined heat capacity, the benefit of solder time diminishes the longer the contact time is. Component surfaces and connector pin material and machine parameters like pump power as well as environmental conditions show little to no impact within a reasonable operation window.

Impact of plasma induced damage on the fabrication of 3D NAND flash memory

A physical process model for dry plasma etching is presented and applied to simulate vertical channel hole etching, a critical fabrication step in modern three-dimensional (3D) NAND flash memory. The presence of physical etching with high energy ions is shown to induce damage in the underlying silicon, which results in the formation of voids during the subsequent selective epitaxial growth (SEG) step. In this manuscript, we present a model for ion induced damage by storing it as a surface property during the plasma etching simulation. A specialized advection algorithm is subsequently applied to simulate silicon SEG on the bottom source line. The model clearly shows the damage caused by the high energy particles, on the crystal nature of silicon, resulting in poor coverage during the SEG step. The removal of this damaged layer using lower energy plasmas results in highly crystalline epitaxially grown silicon. The simulation results show excellent agreement with experiments in the formation of undesired voids without the low-energy pre-epitaxial plasma treatment.

Effect of Hole on Oil Well Cement and Failure Mechanism: Application for Oil and Gas Wells.

Cementing is an important operation in the drilling process. During the cementing process, mud cake, fracturing, perforation, and so on will cause holes in the cement sheath. Thereby, the size effect will reduce the cement strength, which will seriously affect the cementing quality. Several hole types were drilled to study the mechanical properties and damage mechanism of oil well cement. The stress distribution and failure process of cement containing a hole were studied using RFPA2D software. The experimental and simulation results demonstrate that an internal hole has an obvious effect on the cement performance. The hole will change the cement bearing capacity and affect the fracture direction. Three crack types exist: tensile, shear, and far-field. Both 2 and 5 mm vertical eccentric holes can reduce the cement tensile stress. Furthermore, the specimen tensile strength decreases with an increase in the diameter of holes. Horizontal eccentric holes with diameters of 2 and 5 mm will increase the cement tensile strength. Among these, the sample L2-2 exhibits a long crack path, high energy consumption, and a remarkable enhancement effect.

Study on Extraction of Cold Air through a Vertical Hole from a Large Snow Mound ― One Consideration on Heat Exchange with Humid Air through a Vertical Snow Hole ―

Study on Extraction of Cold Air through a Vertical Hole from a Large Snow Mound ― One Consideration on Heat Exchange with Humid Air through a Vertical Snow Hole ―