Simple Hole Research Articles

Evidence for Magnetized Basin Ejecta on the Moon From Observations and Modeling of Demagnetized Craters

AbstractThe formation of lunar crustal magnetic anomalies is not well understood, and most anomalies are not associated with any obvious geologic features. To investigate further, we studied lunar craters from 100 to 400 km in diameter (totaling 305 craters) that may have demagnetized the crust. We find that the four craters Chaplygin, Keeler, Gauss, and Fermi are highly likely to have demagnetized the crust, based on our statistical methods. We modeled the magnetic source of these craters as a simple hole in a thin magnetized plate, representing the destruction of a surficial magnetized layer (Hypothesis 1). Alternatively, we also simulated the impact demagnetization of deeper‐seated magnetism in the crust by shock and temperature (Hypothesis 2). Some interior magnetization remains unexplained under both hypotheses, but the destruction of a pre‐existing surficial layer of magnetized material is consistent with the location of the peak in each crater's magnetic field. We also find three of the craters are inversely correlated with remotely sensed iron, further supporting our interpretation that the craters demagnetized a surficial layer. The four craters are located on magnetized ejecta deposits from the South Pole‐Aitken, Orientale, and Crisium basins. Hence, these four craters further support the hypothesis that large provinces of magnetized material on the Moon arise from hot impact ejecta that cooled in a dynamo field.

Simple hole transporting material based 2,7- carbazole for perovskite solar cells: Structural, photophysical, and theoretical studies

A simple carbazole-based hole transport material, termed HTM1, has been deposited as thin films. The samples were elaborated via a Physical Vapor Deposition to ensure the production of high-quality thin films. The study of the morphological and photophysical properties of the investigated compound was revealed through Scanning Electron Microscopy, Atomic Force Microscopy, Ultraviolet–Visible, and Photoluminescence spectroscopy. A flat surface with low roughness values was observed in the SEM and AFM images. Moreover, the obtained films revealed a higher absorption in the UV region. Optical parameters such as the energy gap (2.9 eV) and refractive index were determined using transmittance measurements. The temperature-dependent photoluminescence over a range of 77–300 K has also been investigated. It is found that, as the temperature decreases, a new emission band appears, which may be due to the formation of excimers. Added to that, theoretical investigation of the highest occupied molecular orbital, the lowest unoccupied molecular orbital, the density of states, and the optical energy gap were studied using density functional theory (DFT) with the hybrid B3LYP exchange-correlation function and the 6-311G (d,p) basis set. Absorption spectra was generated using the TD-DFT method. The absorption maximum obtained (398 nm) for HTM1 closely matched with the experimental value (393 nm). Following these characterizations, simulation studies on the photovoltaic performances of the HTM1 for perovskite solar cells have been done. This cell provided a maximum PCE of 21.31%.

Rhegmatogenous retinal detachment in highly myopic eyes with implantable collamer lens.

To investigate the clinical characteristics, treatment methods and outcomes of rhegmatogenous retinal detachment (RRD) in highly myopic eyes with implantable collamer lens (ICL). High myopia patients who received treatment for nontraumatic RRD after ICL implantation surgery at the Retinal Department of Zhongshan Ophthalmic Center from Jan 2018 to Dec 2022 were reviewed. Comprehensive ophthalmologic examinations including visual acuity measurement and digital fundus photography were performed in each patient. A total of nine RRD eyes from nine patients who received V4c-ICL implantation were included. The mean time from ICL implantation surgery to the diagnosis of RRD was 32.44±22.56mo (range, 1-60mo). At the initial visit for RRD, giant retinal tear (GRT), horseshoe tear, simple round hole, and horseshoe tear combined with round hole were detected in 3, 3, 2, and 1 eye(s), respectively, with macula-off in eyes. Eight patients received surgical treatment, and one patient was treated by retinal laser photocoagulation alone. The ICL was preserved in 7 eyes. At the last follow-up, the mean best corrected visual acuity (BCVA) improved significantly from 1.76±1.06 logMAR at presentation to 0.81±1.01 logMAR (P=0.035), and no case of recurrent retinal detachment was found. The morphological presentation of retinal breaks is diverse in this study. The ICL can be preserved in most cases during the course of retinal detachment repair surgery in our data, companied with acceptable visual and anatomical outcomes.

Effect of decreased platelets on postoperative recurrence of chronic subdural hematoma.

Chronic subdural hematoma (CSDH) is commonly treated using simple burr hole surgery. However, postoperative recurrence occurs at a relatively high rate of 10-20%. A decrease in platelet count (PC) may be associated with recurrence via a hemostasis disorder; however, this association has not been well-studied. Therefore, this study aimed to investigate the association between PC and postoperative CSDH recurrence. We retrospectively reviewed the data for CSDHs in 488 cerebral hemispheres of 431 patients who underwent burr hole surgery at our institution between January 2013 and December 2022. The association between preoperative PC and postoperative CSDH recurrence was investigated. We used the first quartile of PC, PC < 170 × 103/μL to define a threshold for decreased PC. In total, 459 cerebral hemispheres with CSDHs in 405 patients were followed up postoperatively for at least 3 months or until CSDH disappeared. CSDH recurred in 39 (8.5%) cerebral hemispheres. The recurrence rate was gradually increased in parallel with a decreasing PC. Among 109 CSDHs with a decreased PC (<170 × 103/μL), 15 (13.8%) recurred, whereas only 24 (6.9%) of 350 CSDHs without a decreased PC recurred (p = 0.03). In univariable logistic analysis, eosinophil-rich blood (≥100/μL eosinophils in peripheral blood) and a decreased PC were significant risk factors. Multivariable analysis showed that eosinophil-rich blood (adjusted odds ratio, 2.51; 95% confidence interval, 1.26-4.99; p = 0.009) and a decreased PC (adjusted odds ratio, 2.15; 95% confidence interval, 1.07-4.35; p = 0.03) were independent risk factors for recurrence. Our study showed that a decrease in PC was associated with postoperative CSDH recurrence. Patients with CSDH and a decreased PC require careful postoperative follow-up.

Spirobifluorene with an asymmetric fluorenylcarbazolamine electron-donor as the hole transport material increases thermostability and efficiency of perovskite solar cells

A structurally simple hole transport material, with an extremely high glass transition temperature, achieves an average initial efficiency of 24.5% and remarkable 85 °C durability in perovskite solar cells.

Strain partitioning in a dual-phase steel under plane strain compression

Modern design of steels with improved mechanical properties is often based on multiphase microstructures such as in dual-phase steels. The tailoring of these alloys requires a thorough understanding of strain partitioning and the correlation of strain related phenomena in different scales and under different loading paths. These questions are usually addressed by means of empirical techniques and numerical simulations using representative volume elements (RVE). The assessed loading conditions are most often simple shear, uniaxial tension, and hole expansion and these studies mainly focus on microstructural damage progression under low strains. This study aims to develop a coupled experimental-numerical approach to examine the fractal nature of strain partitioning in a dual-phase steel (DP600) under plane strain compression. This deformation path allows the achievement of significantly higher strains up to the extension of possibly promoting grain fragmentation within highly deformed shear bands. From a fractal perspective, it is demonstrated the development of micro-scaled shear bands due to microstructural heterogeneities within macro-shear bands characteristic of plane strain compression. Additionally, the results obtained from the 2D-RVE model were critically examined and compared with several experiments at different scales to provide further understanding on the limitations and capabilities of the approach.

Metamaterial analog of a black hole shadow: An exact ray-tracing simulation based on the spacetime index of refraction

We show that the equation of null geodesics in spherically symmetric spacetimes in isotropic coordinates is identical to the equation of light ray trajectories in isotropic media in flat spacetime. Based on this analogy we introduce an exact simulation of the light ray trajectories both in these spacetimes and in their metamaterial analogs in terms of the spacetime index of refraction. As unstable light trajectories, the photon spheres form in these metamaterial analogs at exactly the same radial distances as expected from the corresponding black hole geometries. Using the same ray-tracing simulation we find the analog of a simple black hole shadow formed by the metamaterial analog of a Schwarzschild black hole, eclipsing a line of light sources near its analog horizon. Designing such a metamaterial could provide a laboratory setting to explore this recently observed phenomenon.

Semi-supervised learning-based coverage hole detection in cellular networks

For any time-critical mobile network-dependent applications and services, coverage is one of the prominent factors for providing the best Quality of Service (QoS) and Quality of Experience (QoE). A simple Coverage Hole (CH) may degrade the performance and the reputation of any operator by reducing the Key Performance Indicators (KPIs). This is one of the important aspects which need to be planned from the phase of network deployment throughout the whole operational stage. Many factors can cause CH such as attenuation, obstacles and improper network planning. Traditionally, a Drive Test (DT) used to be carried out in order to assess the quality of the mobile network signal. With technological advancement, DT has been replaced by the Minimization of Drive Test (MDT) and included as a part of Self-Organizing Networkss (SONs). The MDT process is applicable to networks that operate in 3G, 4G and 5G technologies. With this method, operators are able to measure network performance with the help of end users' devices. Thus, the network can be managed more conveniently, performance is improved, quality is increased, and maintenance costs are reduced for the network. However, the processing of MDT at the operators' side remains time-consuming and complex especially for CH analysis and detection from mobile network data. Therefore, we present a method by utilising Semi-Supervised Learning (SSL) in this paper so that this task becomes uncomplicated with improved accuracy. Our results show that the proposed method achieves better accuracy than the usual classification algorithm.

Comparisons on flow characteristics and film cooling performance of cylindrical and sister holes with/without internal coolant crossflow

Simulations and comparisons on the influence of internal coolant crossflow of a novel film cooling hole design, called “sister holes”, and a baseline cylindrical hole were performed with an established turbulence model. The results show that sister holes can provide better film cooling performance than the baseline case at three blowing ratios, and as the blowing ratio increases the sister holes show significant advantages. At a high blowing ratio, the simple cylindrical hole provides very poor cooling effectiveness, since the jet penetrates into the passage flow due to the high jet velocity and the action of a counter-rotating vortex pair. Compared with the cases using a plenum feeding the film cooling holes, the cases with internal coolant crossflow show higher laterally-averaged film cooling effectiveness because deflection of the jet is caused by the crossflow.

The coherent electromagnetic field and the effect of the pair distribution function

The effect of two different pair correlation functions, used to model multiple scattering in a slab filled with randomly located spherical particles, is investigated. Specifically, the Percus-Yevick approximation is employed and a comparison with the simple hole correction is made. The kernel entries of the hole correction have an analytic solution, which makes the numerical solution of the integral equations possible. The kernel entries of Percus-Yevick approximation are integrated numerically after a subtraction of the slowly converging part in the integrand. Several numerical examples illustrate the effect of the two pair correlation functions, and we also make a comparison with the predictions Bouguer-Beer law gives.

Ambient processing of methylammonium lead iodide perovskite solar cells via magnetic field-assisted electrodeposition of the precursor film

One of the key strategies to develop halide perovskite solar cells involves the preparation of good quality perovskite layer. Although tackling the issues of perovskite crystallinity and morphology is central to ensuring high photovoltaic performance of the device, the feasibility of large-scale fabrication of perovskite is equally important. In this study, we argue that such aims can be achieved by using a new, scalable fabrication technique based on electrodeposition assisted by an external magnetic field to effectively prepare the high-quality PbI2 precursor and perovskite films. The magnetic field-assisted electrodeposition technique required only 10 min of preparation of the precursor layer, which was subsequently converted to improved perovskite films, as supported by the results from scanning electron microscopy, X-ray diffraction, UV–vis absorption, and photoluminescence. All preparation processes were carried out under ambient conditions with high humidity (50–75% relative humidity). Interestingly, using a simple hole transport layer-free device structure with a carbon back contact, the perovskite film prepared using the magnetic field-assisted electrodeposition method showed 4.2% power conversion efficiency, as well as 0.62 V in open-circuit voltage and 16.65 mA/cm2 in photocurrent at AM 1.5 solar light of 100 mW/cm2. Moreover, the unencapsulated perovskite device prepared using electrodeposition under the external magnetic field also demonstrated high stability under ambient conditions, revealing essentially unchanged power conversion efficiency after 14 days of fabrication. Taken together, this work provides an evidence in support of a relatively unexplored electrodeposition-based strategy as a rapid, facile, scalable, and potentially low-cost preparation of perovskite films for solar cells.

Postoperative recurrence of chronic subdural hematoma is more frequent in patients with blood type A.

Because of an aging society, the incidence of chronic subdural hematoma (CSDH) is increasing. This lesion is treated with simple burr hole irrigation, but one of the major issues is that CSDH frequently recurs. ABO blood type may be associated with a bleeding tendency and inflammation. However, its association with the recurrence of CSDH remains unknown. Therefore, the authors of the present study aimed to retrospectively investigate the association between ABO blood type and CSDH recurrence. The authors retrospectively analyzed symptomatic CSDHs in 425 cerebral hemispheres of 376 patients who had undergone surgical treatment with irrigation of the hematoma via burr holes at their institution from January 2011 to September 2019. Among these were 366 CSDHs in 320 patients whose ABO blood type had been determined and who were included in this study. In the study, 307 patients with CSDHs in 350 hemispheres were followed up postoperatively until the disappearance of the CDSH or for at least 3 months. Recurrence of CSDH was observed in 37 patients (10.6%) after surgical treatment. Blood type A was found to be significantly associated with CSDH recurrence compared to non-A blood types: 24 of 153 CDSHs (15.7%) versus 13 of 197 CDSHs (6.6%) (p = 0.008). In the multivariable regression analysis, blood type A, in addition to thrombocytopenia, was a significant independent predictor of the recurrence of CSDH. The study results showed that blood type A is an independent risk factor for the postoperative recurrence of CSDH and that careful follow-up in these patients may be needed.

Black holes in the scalar-tensor formulation of 4D Einstein-Gauss-Bonnet gravity: Uniqueness of solutions, and a new candidate for dark matter

In this work we study static black holes in the regularized 4D Einstein-Gauss-Bonnet theory of gravity; a shift-symmetric scalar-tensor theory that belongs to the Horndeski class. This theory features a simple black hole solution that can be written in closed form, and which we show is the unique static, spherically-symmetric and asymptotically-flat black hole vacuum solution of the theory. We further show that no asymptotically-flat, time-dependent, spherically-symmetric perturbations to this geometry are allowed, which suggests that it may be the only spherically-symmetric vacuum solution that this theory admits (a result analogous to Birkhoff's theorem). Finally, we consider the thermodynamic properties of these black holes, and find that their final state after evaporation is a remnant with a size determined by the coupling constant of the theory. We speculate that remnants of this kind from primordial black holes could act as dark matter, and we constrain the parameter space for their formation mass, as well as the coupling constant of the theory.

Modification of Wright’s Technique for C2 Translaminar Screws Based on Medical Imaging Analysis

Background: To describe and explain the improvement of Wright C2 transforaminal screw fixation technique. Methods: 23 male patients and 10 female patients (a total of 33 patients, average age of 55 years) were implanted with lamina screws on one side or both sides by improved technique. Adopt improved technology, there is a simple hole in the middle of the lateral brain plate, and the screw can be seen directly to prevent the spine from being invaded. Results: With the improved technique, 169 minutes (90–210 minutes) is the average operation time, and 136 ml (80–420 minutes) is the estimated average blood loss. Average length of 26.5 mm (range 24–30) plate screws. After an average follow-up of 12.4 (1.5–30) months, all patients achieved good clinical outcomes. Conclusions: To modify the Wright’s technique, an additional unicortical “hole” was in the middle of the backplane. Through this improved technique, the screw can be directly seen to be inserted into the dorsal cortex of the lamina, thereby reducing the risk of invading the spinal canal and shortening the operation time.

Lost horizon? – modeling black holes in string theory

The modeling of black holes is an important desideratum for any quantum theory of gravity. Not only is a classical black hole metric sought, but also agreement with the laws of black hole thermodynamics. In this paper, we describe how these goals are obtained in string theory. We review black hole thermodynamics, and then explicate the general stringy derivation of classical spacetimes, the construction of a simple black hole solution, and the derivation of its entropy. With that in hand, we address some important philosophical and conceptual questions: the confirmatory value of the derivation, the bearing of the model on recent discussions of the so-called 'information paradox', and the implications of the model for the nature of space.

Charged black-bounce spacetimes

Given the recent development of rotating black-bounce-Kerr spacetimes,for both theoretical and observational purposes it becomes interesting to see whether it might be possible to construct black-bounce variants of the entire Kerr-Newman family.Specifically, herein we shall consider black-bounce-Reissner-Nordström and black-bounce-Kerr-Newman spacetimes as particularly simple and clean everywhere-regular black hole “mimickers” that deviate from the Kerr-Newman family in a precisely controlled and minimal manner, and smoothly interpolate between regular black holes and traversable wormholes.While observationally the electric charges on astrophysical black holes are likely to be extremely low, |Q|/m ≪ 1, introducing any non-zero electric charge has a significant theoretical impact. In particular, we verify the existence of a Killing tensor (and associated Carter-like constant) but without the full Killing tower of principal tensor and Killing-Yano tensor, also we discuss how, assuming general relativity, the black-bounce-Kerr-Newman solution requires an interesting, non-trivial matter/energy content.

Adiabatic effectiveness and heat transfer measurements of simple and trenched cylindrical holes with backward injection

Recent studies have demonstrated that the simple cylindrical hole with backward injection, where the jets are injected reverse to the mainstream flow direction, outperforms its forward-injected counterpart at relative high blowing ratios. Meanwhile, trench is known to be of high cooling effectiveness with forward injection at high blowing ratios. Few studies addressed the combination of the two setups. The present study investigated the simple and trenched cylindrical hole configurations with either forward or backward injection by experiments. The injection angle was 30° and 150° for the forward and backward setup separately. The trench had a depth of 0.75D and the trench width was 1D and 2D. Adiabatic effectiveness was measured with PSP, and heat transfer augmentation was obtained with transient method using the IR camera. Detailed distributions were obtained. Blowing ratio was varied from 0.25 to 4.0. The density ratio was 1.0 or 1.5 in PSP measurements, and was 1.0 only for the heat transfer measurements. For the simple cylindrical hole with backward injection, the result confirmed the advantage of it at high blowing ratios, and also showed that its adiabatic effectiveness is highly uniform in the spanwise direction. Meanwhile, the backward-injected configuration had a much more stable cooling performance as the VR varied. It was further pointed out that the flow field of the simple backward-injected case is governed by the recirculated region downstream the hole exit. The narrow trench enhanced the effectiveness hugely along with forward injection, while the enhancement to the simple backward injection was quite limited. Moreover, the narrow trench performed far better than the wide trench. It was revealed that the key of the mechanism depends on the interaction of the jet with the downstream trench wall.

A Simple and Fast Hole Detection Algorithm for Triangulated Surfaces

Abstract We present a simple and fast algorithm for computing the exact holes in discrete two-dimensional manifolds embedded in a three-dimensional Euclidean space. We deal with the intentionally created “through holes” or “tunnel holes” in the geometry as opposed to missing triangles. The algorithm detects the holes in the geometry directly without any simplified geometry approximation. Discrete Gaussian curvature is used for approximating the local curvature flow in the geometry and for removing outliers from the collection of feature edges. We present an algorithm with varying degrees of flexibility. The algorithm is demonstrated separately for sheets and solid geometries. This article demonstrates the algorithm on triangulated surfaces. However, the algorithm and the underlying data structure are also applicable for surfaces with mixed polygons.

Dual sensing scheduling algorithm for WSN based road network surveillance

In this paper, a dual sensing scheduling algorithm is proposed which is a modified version of VISA technique for sensing scheduling in road networks where targets can enter from both sides of the road. VISA and similar algorithms are based on the idea of designated entrance points and protection points and are very suitable for military scenarios. In comparison, civilian applications mostly use two-way roads and dual carriageways with entrance points on both ends of the roads calling for a modification of the VISA technique to make it suitable for two-way detection. The proposed algorithm achieves detection on a two-way road by using two parallel scan waves originating from the midpoint sensor on the road segment but in opposite directions. The proposed modification of the VISA algorithm improves the detection time by reducing it to half as compared to VISA but at the cost of decreased network lifetime. The proposed algorithm is also compared to Duty Cycling and Always-Awake schemes. In addition, a very simple hole handling method is proposed which applies a comprehensive labeling scheme on all the sensors of the road network represented as vertices in an undirected graph of road network.

Film cooling performance evaluation of the furcate hole with cross-flow coolant injection: A comparative study

Turbine blades are consistently exposed to high-temperature gas in an effort to increase the maximum efficiency of gas turbine engines. Therefore, a growing need exists to protect the outer surfaces from high-temperature gas. Film cooling has long been used as an active thermal protection scheme, and the shaped film-hole is one possible solution to the aforementioned problem. Based on the actual coolant supply channel of the turbine blades, the film cooling performance of a novel furcate hole fed by cross-flow coolant injection with 135-deg ribs was experimentally investigated in this study. The Reynolds numbers of the main-flow and cross-flow are 10,000 and 100,000, respectively, and the blowing ratio M ranges from 0.5 to 2.0. The adiabatic film effectiveness η and heat transfer coefficient of the furcate hole are obtained by the transient liquid-crystal measurement technique, and a detailed comparison between the furcate hole and cylindrical hole geometries, simple and compound hole, is presented. The results show that the span-wise width of the film coverage is significantly more comprehensive than that of the compound hole due to the configuration of the span-wise expansion for the furcate hole. At a lower M, the film coverage gradually narrows, and the η gradually decreases along the flow direction for the furcate hole. The heat transfer enhancement of the furcate hole is the highest among the studied cases, and the heat transfer uniformity is much impoverished. With an increasing M, the advantages of the high η of the furcate hole are gradually revealed. The degree of deflection of the film coverage gradually increases toward the +Y side. Both the effectiveness and magnitude of the span-wise η are improved at M=1.0. At a larger M of 2.0, the heat transfer enhancement is the weakest, and the heat transfer uniformity is improved. The net heat-flux reduction is introduced to comprehensively evaluate the cooling performance. The values of the traditional holes invariably decrease as M increases, whereas that of the furcate hole first increases and then decreases. As M increases to 1.0 and 2.0, the comprehensive benefits of the furcate hole become more apparent.