Single Hole Research Articles

A high-precision detection method of hydroponic lettuce seedlings status based on improved Faster RCNN

In order to improve the efficiency and reduce high cost for seedlings sorting in the raising process of hydroponic lettuce seedlings, we propose an automatic detection method for hydroponic lettuce seedlings based on improved Faster RCNN framework, taking the dead and double-planting status of seedlings growing in a single hole as our research objects. Since the characteristics of hydroponic lettuce seedlings are dense and small in the images, our model uses High Resolution Network (HRNet) as the backbone network for image feature extraction so as to obtain reliable and high- resolution feature expressions. Besides, we adopt focal loss as the classification loss in the Region Proposal Network (RPN) stage to address the imbalance between difficult and easy samples in seedlings classification. We also employ the Region of Interest (RoI) Align instead of the RoI Pooling layer to improve the detection accuracy of seedlings in the different status. The results show that the mean average precision of our method for the hydroponic lettuce seedlings is 86.2%, which is higher than RetinaNet, SSD, Cascade RCNN, FCOS and other detectors. Compared with different feature extraction networks, the detection accuracy of adopting HRNet performs nicely. Therefore, our method presented for the detection of hydroponic lettuce seedlings status can achieve high accuracy and identify seedlings in a problematic status well, which will provide technical support for automatic seedlings detection of hydroponic lettuce.

Evaporation and mixture formation characteristics of diesel spray under various nozzle hole size and injection pressure condition employing similar injection rate profile

The current work demonstrates investigations of the effects of the nozzle hole size and injection pressure on the diesel spray under evaporating condition. Three single hole injectors with hole diameters of 0.101 mm, 0.122 mm and 0.133 mm were used and their injection rate profiles were shaped in a similar manner. Laser Absorption Scattering technique was implemented in the diesel spray experiments to visualize the vapor phase and measure the mixture concentration. Also, the experimental results were validated with the computational approach. The injection rate profile and initial spray trajectory angle are key inputs for the CFD simulation; thus, careful measurements were taken. The injection rate profiles were measured by Zeuch method and based on the start of injection with the High-speed Video camera frame, the 5 kHz Butterworth low pass filter was applied to the injection rate raw signal. Moreover, the near nozzle field microscopic spray imaging experiments were performed to measure the initial spray trajectory angle. The experimental results show that the 0.101 mm hole diameter injector promotes shorter liquid length, longer vapor length, higher evaporation ratio and higher entrained air mass. The computational results show a reasonable qualitative agreement with the experiments; however, a quantitative discrepancy can be noticed.

Photon wave-mechanical theory of single-photon diffraction from a mesoscopic hole

A quantum electrodynamical theory for single-photon diffraction of light from a mesoscopic hole in a quantum well (QW) screen with (Schrödinger) electron dynamics is established. Photon wave mechanics (PWM) is used to extend and bridge the gap between hitherto used semiclassical and quantum optical theoretical approaches for analyses of diffraction of light. An essentially complete calculation is carried out for a paradigm example: (i) a single-photon point-like electric-dipole (ED) primary source, emitting (ii) a wave packet photon toward (iii) a two-level QW screen possessing (iv) in-plane jellium electrodynamics with (v) a single mesoscopic ED hole. The PWM description is based on the, in this context attractive, Riemann–Silberstein–Oppenheimer–Bialynicki formulation. The effective size of the hole is determined on the basis of a quantum mechanical extinction theorem for the in-plane jellium electron dynamics in the vicinity of the hole. The incident electrodynamic field induced current density in the screen (with hole) allows one to obtain the single-photon probabilities for scattering from the hole and the screen. A one-photon wave train emitted by the primary ED point-like source is assumed to drive the scattering process. The far-field hole-screen diffraction pattern is calculated paying particular attention to the spectral diffraction (correlation) pattern, which illustrates the interplay between the wave-train frequency, the screen/hole local-field resonance frequency, and the Bohr frequency. Our theory shows that the ED hole polarizability is close to that of a one-dimensional single harmonic oscillator with resonance frequency coinciding with the local-field resonance in the two-level QW screen.

Single Burr-Hole Extended Transforaminal Approach for Concurrent Endoscopic Surgery in the Third Ventricle Posterior to the Foramen of Monro and Ventriculostomy: Clinical Series and Planning Steps

For endoscopic surgery of third ventricular lesions posterior to the foramen of Monro that frequently require a third ventriculostomy during the same procedure, the extended transforaminal approach (ETFA) through the choroid fissure has been proposed. This study reports clinical results and provides anatomic background and guidelines for individual planning of a single burr-hole approach and a safe transchoroid entry zone. A retrospective review was undertaken of 25 cases of concurrent third ventricle surgery and third ventriculostomy via ETFA. Assessment was made of a safe transchoroidal entry zone on cadavers (6 hemispheres) and of planning guidelines on magnetic resonance imaging showing occlusive hydrocephalus (30 sides). ETFA was feasible in all 25 cases. The safe transchoroid entry zone was sufficient in 16 cases; in 9 cases, additional transchoroid opening with transection of the anterior septal vein was required without clinical consequences. The anatomic study showed a safe transchoroid entry zone of 5 mm (3-6 mm) for posterior enlargement of the foramen of Monro. Individual planning on magnetic resonance imaging of patients with enlarged third ventricles showed an optimal burr-hole position 22 mm (10-30 mm) lateral to the midline and 8 mm (27 to -23 mm) precoronal; a foramen of Monro diameter of 7 mm (3-11 mm) and a safe transchoroid entry zone of 6 mm (3-12 mm). According to our data, concurrent endoscopic surgery of third ventricular lesions posterior to the foramen of Monro and ventriculostomy are feasible through a single burr hole and a transchoroid extension of the transforaminal approach. Precise preoperative planning is recommended for anticipating the individual anatomic nuances.

Single Microhole per Pixel in CMOS Image Sensors With Enhanced Optical Sensitivity in Near-Infrared

Silicon photodiode-based CMOS sensors with backside-illumination for 300-1100 nm wavelength range were studied. We showed that a single hole in the photodiode increases the optical efficiency of the pixel. In near-infrared wavelengths, the enhancement allows 70% absorption in a 3 μm thick Si. It is 4× better than that for the flat pixel. We compared different shapes and sizes of single hole and hole arrays. We have shown that a certain size and shape in single hole-based pixels contribute to stronger enhancement of optical efficiencies. The crosstalk was successfully reduced by employing trenches between pixels. We optimized the dimensions of the trenches to achieve minimal pixel separation for 1.12 μm pixels.

Surgical occlusion of middle meningeal artery in treatment of chronic subdural haematoma: anatomical and technical considerations.

The primary aim of chronic subdural haematoma (CSDH) treatment is to relieve pressure to improve neurological symptoms. The secondary aim is to avoid recurrence. The blood supply from the middle meningeal artery (MMA) to the haematoma membranes has recently become a research target, to enhance our understanding of the processes leading to growth and re-growth of a CSDH. Several studies indicate that endovascular embolization of the MMA (eMMA) reduces recurrence rates, but this effect must be confirmed in a randomized controlled setting. Endovascular embolization is an advanced and costly procedure carrying a significant risk of embolism in the elderly. The aim of this study was to assess anatomical and technical aspects of surgical occlusion of the MMA (soMMA) via a single same-procedure burr hole, as an alternative to eMMA. Technical aspects of soMMA were assessed using cadaver head dissection. MMA anatomy was examined by mapping the branching pattern and distribution of MMA in dry skulls, and CSDH position was investigated by analysis of computed tomography (CT) of CSDHs. Finally, we evaluated the possibility of CT-guided navigation to mark the branching point of the anterior MMA division on the skin. We established anatomical landmarks to locate the MMA and found that particularly the anterior MMA branch can be occluded through a single burr hole at the pterion during the same procedure as haematoma decompression. CT of 1454 CSDHs in 1162 patients showed that the CSDH was anteriorly located in 57.5% compared with posteriorly in only 3%. This correlated with the anterior branch of the MMA being dominant in 58% of dry skull samples examined. We further confirmed that the MMA can be localized by neuronavigation as an alternative to using anatomical landmarks and average measurements. A CSDH is mainly anteriorly located and supposedly primarily supplied by the anterior MMA branch. In a simulated setting, soMMA can be performed during the same procedure as haematoma decompression. A few reservations notwithstanding, we find that soMMA may be a viable alternative to eMMA in most CSDH cases and that soMMA should be further evaluated in a clinical setting.

Effects of Bulk Flow Pulsations on Film Cooling with Two Sister Holes

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.

Energy Absorption in Carbon Fiber Composites with Holes under Quasi-Static Loading

Composite tubular structures have shown promise as energy absorbers in the automobile industry. This paper investigates the energy absorption characteristics of carbon fiber reinforced plastic (CFRP) tubes with pre-existing holes. Holes may represent an extreme case of impact damage that perforates the tube, e.g., stones from road surface impacting the tubes. Tubes with holes represent more conservative performance characteristics, since impact damage of the same size will have residual material, which may carry some load. Tubes with holes can provide the lower limit of CFRP tube performance under axial crushing relative to impact damaged tubes with perforation diameter close to the hole diameter. In this study, tubes with lay-up of [05/902/04] with one and two holes in defined locations and different diameters are experimentally studied under quasi-static loading. It was found that specific energy absorption (SEA) reduces by 50% with one or two holes of 15 mm size, 100 mm from top of the tube. The SEA reduction is about 60% lower than the regular tube when the diameter of the hole is 20 mm located at 100 mm from top. The most severe reduction occurs if the location of single or double holes are 75 mm from the top. In this case, a SEA reduction of 75% can be expected. Results indicate that holes can significantly alter the energy absorption capability of the tubes. It is also clear that in axial crushing of composite tubes, the location of the hole (100 to 75 mm) appears to create more pronounced effect than the size of the hole itself (15 vs. 20 mm) for the cases investigated. The failure modes for tubes with holes seem to preserve similar damage modes with delamination, frond creation, and brittle fracture, which is typically observed in regular composite tubes under axial crushing load. This is due to primarily front end crushing, which dominates the failure modes, while hole induced damage occurs later.

Effect of protective layer deposition in cross-sectional analysis of focused ion beam in germanium substrate

In this work, a single micro-size circular and rectangular holes were fabricated in phosphorus/tin implanted germanium substrate using ion milling of FIB, for potential application in photonic crystal and FINFET. One of the important analysis that need to be done in the future is a cross-sectional analysis in order to evaluate the milling rate of material, redeposition of milled material, and the quality of the milled surface in the pattern structure. However, a well-known practise in preparing a cross-sectional sample for transmission electron microscope analysis using FIB involves a deposition of protective layer on the substrate surface before performing the cross-sectional ion milling, in order to prevent the surface damage. Taking this into consideration, this work performed a preliminary study to analyze the effect of depositing a protective layer onto the hole for performing FIB cross-sectional analysis of the fabricated hole structures. Two-step deposition technique of platinum layer involving electron beam, followed by ion beam was performed on the hole prior to the cross-sectional milling. Hole structure without protective layer was also prepared as a comparison. It is found that although the depth of the milled area can be evaluated in both cross-sectioned holes with/without protective layer, an evaluation on roughness and redeposition are difficult, specifically in the one with protective layer. While the existence of secondary damage might affect the quality of milled surface during the cross-sectional milling in the sample without protective layer.

Breakup of thin liquid sheets through hole–hole and hole–rim merging

Abstract

Interaction effects on heat conduction and thermal stress in an infinite elastic plane with two circular holes

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.

Computationally Guided Discovery of Axis-Dependent Conduction Polarity in NaSnAs Crystals

Most electronic materials exhibit a single dominant charge carrier type, either holes or electrons, along all crystallographic directions. However, there are a small number of compounds, mostly metals, that exhibit simultaneous p-type and n-type conduction behavior along different crystallographic directions. We demonstrate that the experimental discovery of semiconductors with this axis-dependent conduction polarity can be facilitated by identifying a large anisotropy of either the electron or hole effective masses (m*) or both, providing the electron and hole masses dominate along different crystallographic directions. We calculated the layered semiconductor NaSnAs to have a lower electron m* in-plane than the cross-plane and a very large hole m* in-plane and small hole m* cross-plane. We established the growth of >3 mm-sized NaSnAs crystals via Sn flux and confirmed the band gap to be 0.65 eV, in agreement with theory. NaSnAs exhibits p-type thermopowers cross-plane and n-type thermopowers in-plane, confirming that the large anisotropy in the effective mass at the band edges is an excellent indicator for axis-dependent conduction polarity. Overall, this work shows that the discovery of semiconductors with such a phenomenon can be accelerated by computationally evaluating the anisotropic curvatures of the band edges, paving the way for their future discovery and application.

Dominant Fifth-Order Correlations in Doped Quantum Antiferromagnets.

Traditionally, one- and two-point correlation functions are used to characterize many-body systems. In strongly correlated quantum materials, such as the doped 2D Fermi-Hubbard system, these may no longer be sufficient, because higher-order correlations are crucial to understanding the character of the many-body system and can be numerically dominant. Experimentally, such higher-order correlations have recently become accessible in ultracold atom systems. Here, we reveal strong non-Gaussian correlations in doped quantum antiferromagnets and show that higher-order correlations dominate over lower-order terms. We study a single mobile hole in the t-J model using the density matrix renormalization group and reveal genuine fifth-order correlations which are directly related to the mobility of the dopant. We contrast our results to predictions using models based on doped quantum spin liquids which feature significantly reduced higher-order correlations. Our predictions can be tested at the lowest currently accessible temperatures in quantum simulators of the 2D Fermi-Hubbard model. Finally, we propose to experimentally study the same fifth-order spin-charge correlations as a function of doping. This will help to reveal the microscopic nature of charge carriers in the most debated regime of the Hubbard model, relevant for understanding high-T_{c} superconductivity.

Search for Gravitational Waves from High-Mass-Ratio Compact-Binary Mergers of Stellar Mass and Subsolar Mass Black Holes.

We present the first search for gravitational waves from the coalescence of stellar mass and subsolar mass black holes with masses between 20-100 M_{⊙} and 0.01-1 M_{⊙}(10-10^{3} M_{J}), respectively. The observation of a single subsolar mass black hole would establish the existence of primordial black holes and a possible component of dark matter. We search the ∼164 day of public LIGO data from 2015-2017 when LIGO-Hanford and LIGO-Livingston were simultaneously observing. We find no significant candidate gravitational-wave signals. Using this nondetection, we place a 90% upper limit on the rate of 30-0.01 M_{⊙} and 30-0.1 M_{⊙} mergers at <1.2×10^{6} and <1.6×10^{4} Gpc^{-3} yr^{-1}, respectively. If we consider binary formation through direct gravitational-wave braking, this kind of merger would be exceedingly rare if only the lighter black hole were primordial in origin (<10^{-4} Gpc^{-3} yr^{-1}). If both black holes are primordial in origin, we constrain the contribution of 1(0.1)M_{⊙} black holes to dark matter to <0.3(3)%.

Hole in the two-dimensional Ising antiferromagnet: Origin of the incoherent spectrum

We develop a "self-avoiding walks" approximation and use it to calculate the spectral function of a single hole introduced into the 2D square lattice Ising antiferromagnet. The obtained local spectral function qualitatively agrees with the exact diagonalisation result and is largely incoherent. Such a result stays in contrast with the spectrum obtained on a Bethe lattice, which consists of the well-separated quasiparticle-like peaks and stems from the motion of a hole in an effective linear potential. We determine that this onset of the incoherent spectrum on a square lattice (i) is not triggered by the so-called Trugman loops but (ii) originates in the warping of the linear potential by the interactions between magnons created along the tangential paths of the moving hole.

A new efficient approach for detecting single and multiple black hole attacks

Mobile Ad hoc NETworks (MANET) are networks without infrastructure. The communication range among nodes is limited, where several hops are needed to transmit a packet from the source to the destination. These networks have a constantly changing topology due to its mobile nodes and their arbitrary connections, which make it vulnerable for different attacks. One of the most important attacks in MANET is the black hole attack which degrades the performance of the network by removing all the packets passing through it. There are several techniques for detecting black hole attacks in the ad hoc on demand vector protocol. In this paper, a new approach based on AACK is proposed. The proposed system is to detect the single and multiple black hole attacks by intrusion detection system with SPlitted AACK technique. The system is robust enough to detect all black hole attacks by using an iterative split of the main path until the detection of the malicious nodes. Network simulator 2 is used for simulation. We tested our system on different networks with different network sizes and different numbers of attacks, and we compared our results with some existing intrusion detection system techniques.

Scalar perturbations of black holes in Jackiw-Teitelboim gravity

We study linear scalar perturbations of black holes in two-dimensional (2D) gravity models with a particular emphasis on Jackiw-Teitelboim (JT) gravity. We obtain an exact expression of the quasinormal mode frequencies for single horizon black holes in JT gravity and then verify it numerically using the Horowitz-Hubeny method. For a 2D Reissner-Nordstr\"om like solution, we find that the massless scalar wave equation reduces to the confluent Heun equation using which we calculate the Hawking spectra. Finally, we consider the dimensionally reduced Ba\~nados-Teitelboim-Zanelli (BTZ) black hole and obtain the exterior and interior quasinormal modes. The dynamics of a scalar field near the Cauchy horizon mimics the behavior of the same for the usual BTZ black hole, indicating a possible violation of the strong cosmic censorship conjecture in the near extreme limit. However, quantum effects seem to rescue strong cosmic censorship.

Experiment and Failure Analysis of Rock‐Like Material Affected by Different Excavation Depths

In order to increase the understanding of the strength and failure mechanism of rock mass during tunnel excavation, a series of uniaxial compression tests were conducted on mortar specimen with cracks and holes by using a rock mechanics servo‐controlled testing system. And by monitoring the experimental process, the initiation, propagation, and coalescence process of cracks were observed and characterized. According to the experimental results, the influences of the excavation depth on the mechanical parameters and fracture characteristics of mortar specimens with single hole and the ones with single‐hole crack were analyzed in detail. In the specimens with single hole, the peak strength decreases with the increase of hole depth, but the peak strain and elastic modulus have no obvious linear correlation with the hole depth. And the position and angle of initial crack change differently with the increase of the hole depth. The position of initial crack moves from the side of the hole to the top of the hole. When the hole depth exceeds 50%, the crack initiation angle is no longer inclined to the axial stress direction, but parallel to the axial stress direction. In the specimens with single prefabricated crack, the wing‐shaped secondary cracks are generated at the tip of the precrack, and the antiwing‐shaped secondary cracks are generated at the tip when approaching the peak stress. However, in the specimens with single‐hole crack, no antiwing‐shaped crack appears. And when the hole depth reaches 80%, two wing‐shaped cracks appear at the precrack tip. One of the new wing‐shaped cracks appears in the direction of the extension line of the precrack.

A New Method for Reducing Collapsibility of Loess Foundation with Thicker Deposit: The Borehole Preimmersion Method

At present, there are some key issues in the traditional preimmersion method for reducing the collapsibility of the loess ground, such as the difficulty in determining the total water consumption and the long immersion time. In response to these issues, a new method, the borehole preimmersion method, is presented, and a specific theoretical design model is proposed for application in projects. The method is specifically discussed from a new perspective, and the diffusion mechanism and evolution law of water in the ground are presented in detail through theoretical analysis and numerical calculation, respectively. The water diffusion is a mushroom‐type form for a single water injection hole immersed in water. A calculation model derived for a single water injection hole or a group of water injection holes based on the research results is used to calculate the volumes of soaked loess and the total water consumption. Through an in situ immersion test, the treatment effect of this method is evaluated to verify the rationality of the method and the theoretical calculation model proposed in this study, which provides a new method and theoretical framework for effectively reducing the collapsibility of the loess ground.

Improved Sound Absorption Properties in Polyurethane Foams by the Inclusion of Al2O3 Nanoparticles

At present, the scale of China’s power grid is becoming larger and larger, and the control of low‐frequency noise in substations (especially for transformers) is very important. The sound‐absorbing materials have become one of the important ways to control low‐frequency noise. The single polyurethane material cannot satisfy the requirements for reducing low‐frequency noise, so it is very necessary to study its composite with other materials. In the paper, the flexible polyurethane foam and Al2O3 nanoparticle composites were obtained by the impregnation method. The method was simple, safe, and easy to control. The morphology and sound absorption coefficient of the foam materials before and after filling were analyzed. Single‐hole acoustic cavity models of PU and Al2O3‐PU composite were established through the finite element. The absorption and dissipation process of sound pressure for single hole was studied to understand the energy dissipation process. Meanwhile, through studying acoustic energy storage and acoustic energy dissipation, the loss factor of a single hole was obtained, which can predict the change rule of the sound absorption coefficient for PU foam and Al2O3‐PU.