Vertical Segments Research Articles

Experimental Study on Gas-Solid Two-Phase Flow Characteristics of a Vertical Cyclone Combustor System.

According to the design and operational parameters of the cyclone liquid slag-discharging boiler, an experimental platform for the cyclone burner was designed and constructed in a cold state based on the principle of similarity. The experimental study investigated the effects of parameters, such as swirl-vane angles, coal concentration, operating parameters, and particle size, on the flow distribution and vertical riser resistance characteristics of the vertical cyclone burner. The results showed that there were differences in flow distribution among the cyclone burners, and the most uniform flow distribution was achieved when the swirl-vane angle of the primary air was 30°. The concentration of pulverized coal significantly influenced the pressure drop in the vertical ascending section, which increased with higher concentrations of pulverized coal. When the concentration of pulverized coal remains constant, the pipeline pressure drop is minimized at a primary air velocity of 7.5 m/s. As the secondary wind speed increased, the pressure drop consistently rose; when the secondary wind speed is 22 m/s, the pressure drop of the pipeline is the maximum; however, excessively high secondary wind speeds were found to be detrimental to the formation of an optimal aerodynamic field in the burner. Furthermore, when the pulverized coal concentration was held constant, materials with larger particle sizes exhibited the highest pressure drop. When the particle size increases from 50 to 150 μm, the pressure drop of the vertical riser segment also increases. Finally, based on the Barth additional pressure drop theory, the pressure drop formula of the vertical riser is fitted by a dimensional analysis method, and the correlation formula of the pressure drop test of gas-solid two-phase flow in the vertical riser is obtained.

STUDY OF FACIAL NERVE COURSE AND ITS VARIATION IN TEMPORAL BONE DISSECTION

Objectives: There are various anatomical variations of the facial nerve in the bony canal making it prone to injury during mastoid surgeries. The objective of the present study is to find the course of the facial nerve and its variation in 40 cases of temporal bone dissection and to evaluate various parameters of the tympanomastoid segments of the facial nerve and its relation with the important middle ear structures. Methods: The present study was conducted in the Department of Otolaryngology, Uttar Pradesh University of Medical Sciences, Saifai, Etawah, on 40 temporal bones from January 2022 to December 2022. Various parameters of the tympanomastoid segments of the facial nerve and its relations with the important middle ear structures were studied in the present study. Results: In the present study, out of 40 bones dissected, 34 bones (85%) were well pneumatized whereas 6 bones (15%) were sclerotic in nature. In the present study, tympanic segment length varied from 7.65 to 11.72 mm with a mean of 9.32 mm (±1.02 mm). Vertical segment length varied from 10.2 to 15.9 mm with a mean of 13.48 mm (±1.21 mm). The distance of the second genu from the outer cortex varied from 17.67 to 23.71 mm with a mean of 19.73 mm (±1.44 mm). The distance of chorda tympani from stylomastoid foramen varied from 3.2 to 7.6 mm with a mean of 5.54 mm (±1.41 mm). Conclusion: Anatomical knowledge of facial nerve in the canal and its relation to surrounding structures is very helpful for ENT surgeons to avoid injury to it during middle ear surgeries.

B0-VPG Representation of AT-free Outerplanar Graphs

A $k$-bend path is a non-self-intersecting polyline in the plane made of at most $k+1$ axis-parallel line segments. B$_{k}$-VPG is the class of graphs which can be represented as intersection graphs of $k$-bend paths in the same plane. In this paper, we show that all AT-free outerplanar graphs are B$_{0}$-VPG, i.e., intersection graphs of horizontal and vertical line segments in the plane. Our proofs are constructive and give a polynomial time B$_{0}$-VPG drawing algorithm for the class. In fact, we show the existence of a B$_{0}$-VPG representation for a superclass of AT-free graphs namely linear outerplanar graphs which we define as the class of subgraphs of biconnected outerpaths. Outerpaths are outerplanar graphs which admit a planar drawing whose weak dual is a path. Following a long line of improvements, Gonçalves, Isenmann, and Pennarun [SODA 2018] showed that all planar graphs are B$_{1}$-VPG. Since there are planar graphs which are not B$_{0}$-VPG, characterizing B$_{0}$-VPG graphs among planar graphs becomes interesting. Chaplick et al. [WG 2012] had shown that it is NP-complete to recognize B$_{k}$-VPG graphs within B$_{k+1}$-VPG. Hence recognizing B$_{0}$-VPG graphs within B$_{1}$-VPG is NP-complete in general, but the question is open when restricted to planar graphs. There are outerplanar graphs and AT-free planar graphs which are not B$_{0}$-VPG. This piqued our interest in AT-free outerplanar graphs.

Time- and Energy-Saving Potentials of Efficient Urban Air Mobility Airspace Structures

Novel electric propulsion technology has given rise to thinking about urban air mobility in a new way with its expected high degree of operational flexibility. The designs of electric vertical takeoff and landing configurations are determined by their mission profile, which we found to be oversimplified at many points in the current scientific literature. There is a gap of understanding in how mission profiles impact travel time and energy demand. In this paper, we review various mission designs, formulate a five-segment flight profile (including vertical ascent, climb, cruise, descent, and vertical approach), and apply it on a fleet level of up to 200,000 urban air mobility trips. The demand data originate from the Upper Bavaria region study, OBUAM. In a sensitivity study, we vary the cruise altitude, the height of the vertical flight segments, and the climb and descent angles for two vehicle configurations: a fixed-wing tilt-rotor concept, and a multicopter concept. The main findings for the fixed-wing concept are that the height of the vertical flight segments and the cruise altitude should be as low as possible, and small climb angles (below 7 deg) should be avoided. The multicopter concept, however, is penalized by fast forward flight while being comparatively insensitive to both the cruise altitude and height of the vertical flight segments. Furthermore, we found a tradeoff between time- and energy-optimal flights with the a energy-optimized climb/descent angle at around 10 deg.

Global minimizers of a large class of anisotropic attractive‐repulsive interaction energies in 2D

AbstractWe study a large family of Riesz‐type singular interaction potentials with anisotropy in two dimensions. Their associated global energy minimizers are given by explicit formulas whose supports are determined by ellipses under certain assumptions. More precisely, by parameterizing the strength of the anisotropic part we characterize the sharp range in which these explicit ellipse‐supported configurations are the global minimizers based on linear convexity arguments. Moreover, for certain anisotropic parts, we prove that for large values of the parameter the global minimizer is only given by vertically concentrated measures corresponding to one dimensional minimizers. We also show that these ellipse‐supported configurations generically do not collapse to a vertically concentrated measure at the critical value for convexity, leading to an interesting gap of the parameters in between. In this intermediate range, we conclude by infinitesimal concavity that any superlevel set of any local minimizer in a suitable sense does not have interior points. Furthermore, for certain anisotropic parts, their support cannot contain any vertical segment for a restricted range of parameters, and moreover the global minimizers are expected to exhibit a zigzag behavior. All these results hold for the limiting case of the logarithmic repulsive potential, extending and generalizing previous results in the literature. Various examples of anisotropic parts leading to even more complex behavior are numerically explored.

Enumerating floorplans with walls

Let P be a set of n points in the proper inside of an axis-aligned rectangle R, and each point in P has a type, which is h-type, v-type, or f-type. Those are shortened forms of horizontal type, vertical type, and free type. We wish to dissect R into a set S of n+1 rectangles by n horizontal or vertical line segments so that each point in P is on the common boundary line segment between two rectangles in S, and also each h-type point in P is on a horizontal line segment, each v-type point in P is on a vertical line segment, and each f-type point in P is on a horizontal or vertical line segment. Such a dissection of R is called a feasible floorplan of R with respect to P. Each point in P corresponds to the location of a structurally necessary horizontal or vertical wall, or a column (pillar) to support the upper part. In this paper, when P consists of points of the three described types, we present an efficient algorithm that enumerates all the feasible floorplans of R with respect to P. The algorithm is based on the reverse search method and enumerates all the feasible floorplans in O(n|SP|) time using O(n2) space, after O(nlogn) time preprocessing, where SP is the set of the feasible floorplans of R with respect to P. Moreover, we show that, after O(nlogn) time preprocessing, one can enumerate all feasible floorplans in SP in O(n) delay using O(n2) space.

The Largest Quadrilateral is Cyclic: A New Geometric Proof

Although treated as “obvious” since antiquity, the first complete proof that “a quadrilateral with given sides achieves the maximum area when it is cyclic” is attributed to Bretschneider (1842), who proved it using trigonometry. Peter (2003) proved it using calculus. It also follows from the isoperimetric inequality, proved geometrically in [5] and [11]. Here we give a new Euclidean geometric proof, starting from a different maximization problem: Find the tallest vertical line segment sandwiched between two semi-circles in a plane lying on opposite sides of a horizontal line with (partially) overlapping diameters.

Finding geometric representations of apex graphs is NP-hard

Planar graphs can be represented as the intersection graphs of different types of geometric objects in the plane, e.g., circles (Koebe, 1936), line segments (Chalopin & Gonçalves, SODA 2009), L-shapes (Gonçalves et al., SODA 2018). For general graphs, however, even deciding whether such representations exist is often NP-hard. We consider apex graphs, i.e., graphs that can be made planar by removing one vertex from them. We show, somewhat surprisingly, that deciding whether geometric representations exist for apex graphs is NP-hard as well.More precisely, we show that for every fixed positive integer g and every graph class G such that ▪, it is NP-hard to decide whether an input graph belongs to the graph class G, even when the inputs are restricted to apex graphs of girth g. Here, ▪ is the class of intersection graphs of axis-parallel line segments (where horizontal segments intersect only vertical segments), and ▪ is the class of intersection graphs of simple curves (where two intersecting curves cross each other exactly once) in the plane. This partially answers an open question raised by Kratochvíl & Pergel (COCOON, 2007).Most known reductions for earlier proofs of NP-hardness for these problems are from variants of 3-SAT (mainly Planar 3-Connected 3-SAT). We reduce from the ▪▪▪ problem, which uses the more intuitive notion of planarity. As a result, our proof is much simpler and encapsulates several classes of geometric intersection graphs.

Joint Design of Horizontal and Vertical Polarization Waveforms for Polarimetric Radar via SINR Maximization

For an extended target with different polarimetric response, one way of improving the detection performance is to exploit waveform diversity on the dimension of polarization. In this paper, we focus on joint design of transmit signal and receive filter for polarimetric radars with local waveform constraints. Considering the signal-to-interference-plus-noise ratio (SINR) as the figure of merit to optimize, where the average Target-Impulse-Response Matrix (TIRM) within a certain Target-Aspect-Angle (TAA) interval is employed as the target response, the waveform is decomposed and then designed for both horizontal and vertical polarization segments, subject to energy and similarity constraints. An iterative algorithm is proposed based on the majorization-minimization (MM) method to solve the formulated problem. The developed algorithm guarantees the convergence to a B-stationary point, where in each iteration, optimal horizontal and vertical transmit waveforms are respectively solved by using the feasible point pursuit and successive convex approximation (FPP-SCA) technique. Experiment results show the effectiveness of the proposed algorithm, the robustness of the output SINR against the TAA change, and the advantages of polarization diversity and local design.

Poincaré–Reeb graphs of real algebraic domains

An algebraic domain is a closed topological subsurface of a real affine plane whose boundary consists of disjoint smooth connected components of real algebraic plane curves. We study the geometric shape of an algebraic domain by collapsing all vertical segments contained in it: this yields a Poincaré–Reeb graph, which is naturally transversal to the foliation by vertical lines. We show that any transversal graph whose vertices have only valencies 1 and 3 and are situated on distinct vertical lines can be realized as a Poincaré–Reeb graph.

Solidification Principle in Large Vertical Steel Casting Under the EMS Effect

The surging demand for large high-quality rotor shafts or similar steel components in heavy industries (energy sector) poses new challenges to steelmakers. Based on the experience of conventional ingot and continuous casting, several new process concepts have been proposed, e.g., vertical continuous casting (VCC), semi-continuous casting (SCC), and segment casting (SC), but none of them are optimally put in operation. The main problems include the control of the as-cast structure and macrosegregation. Electromagnetic stirring (EMS) is necessary to obtain the center equiaxed zone, but EMS-induced multiphase flow can cause severe macrosegregation and uneven distribution of the as-cast structure between equiaxed and columnar. In this study, an advanced mixed columnar-equiaxed solidification model was used to investigate the formation of the as-cast structure and macrosegregation in an example of SCC with a large format (diameter 1 m). The main role of EMS is to create crystal fragments by fragmentation, which is regarded in this work as the only origin of equiaxed grains. The created equiaxed grains are brought by the EMS-induced (primary and secondary) flow and gravity-induced sedimentation to the central/lower part of the casting. The main goal of this study was to understand the solidification principle of SCC. In addition, a numerical parameter study by varying the EMS parameters was also performed to demonstrate the model capability towards the process optimization of SCC.

Evaluation of Ocular Diameter Parameters Using Swept-Source Optical Coherence Tomography.

Purpose: To investigate the iridocorneal angle-to-angle (ATA), sclera spur-to-sclera spur (STS), and white-to-white (WTW) ocular diameters and their potential influence on anterior chamber intraocular lens (ACIOL) and implantable collamer lens (ICL) sizing in Chinese subjects by using a swept-source optical coherence tomography system (SS-OCT). Design: A retrospective, observational, cross-sectional study. Methods: In 60 right eyes (60 subjects), the ATA, STS, and WTW were measured in six axes (0°-180°, 30°-210°, 60°-240°, 90°-270°, 120°-300°, and 150°-330°) using SS-OCT. The ACIOL and ICL sizes were calculated based on horizontal and vertical axes anterior segment data. A paired sample t-test was used to test the differences in each parameter across the six axes, the potential difference between each pair of parameters in a given axis, and the artificial lens size difference between the horizontal and vertical directions. Pearson's correlation analysis was used to determine the potential correlation between age and AL, WTW, STS, and ATA distances. Results: ATA and STS were the longest on the vertical and shortest on the horizontal axis, while WTW was similar on both axes. These three parameters differed only in the vertical axis (F = 4.910, p = 0.008). ATA and STS were by 0.23 ± 0.08 mm (p = 0.005) and 0.21 ± 0.08 mm wider (p = 0.010) than WTW, respectively. ICL size was 0.27 ± 0.23 mm smaller when based on the horizontal than on the vertical axis parameters (p < 0.001), while ACIOL remained similar (p = 0.709). Age correlated negatively and axial length positively with all measured values. ATA, STS, and WTW correlated positively in the same axis (all p < 0.001). Conclusions: ATA and STS were longer in the vertical than in the horizontal direction, while WTW measurements remained similar. ATA and STS diameters more accurately depicted anatomic relationships for phakic IOL sizing than WTW.

A Case of Oral Flora Related Carotid Vasculitis (P2-10.007)

<h3>Objective:</h3> NA <h3>Background:</h3> A 41-year-old immunocompetent female with a history of uterine cancer status post hysterectomy, migraines, and anxiety presented to the hospital with a one-month history of headache, myalgias, and subjective fevers. Blood work showed a leukocytosis (16.9) and elevated C-reactive protein (98.3). Other inflammatory markers including erythrocyte sedimentation rate, C3, and C4 were normal. Blood cultures (bcx) were drawn. Physical exam noted neck hypertonicity along with tenderness along vertebral column and neck musculature. Initial computed tomography angiography (CTA) of the head and neck showed narrowing of the left internal carotid artery (ICA) at the junction of horizontal and vertical petrous segments and present to the mid cavernous ICA, which were concerning for dissection/intramural hematoma. MRI with and without contrast did not reveal any other acute pathology. On Hospital Day 3, 1 of 2 bcx grew gram-negative and gram-positive rods. On Hospital Day 6 a repeat MRI showed mild dural thickening and enhancement involving the walls of the left cavernous sinus extending posteriorly along the tentorial leaf and the left cavernous ICA appeared small in size compared to the right ICA. On day 7 cultures speciated to <i>Parvimonas micra</i> 2 of 2 bcx and <i>fusobacterium nucleatum</i> 1 of 2 bcx. Due to the presence of oral flora in bcx, additional history was gathered from the patient. The patient shared with staff a history of incomplete dental work. Oral exam revealed several partially extracted teeth with intact roots. This was felt to be the source of her infection and that her “dissection” was actually an infectious vasculitis. The patient underwent successful root extraction and was treated with 4 weeks of intravenous antibiotics. Interval CTA showed improvement in the left ICA narrowing. <h3>Design/Methods:</h3> NA <h3>Results:</h3> NA <h3>Conclusions:</h3> Here we present to our knowledge the first case of carotid vasculitis secondary to <i>Parvimonas micra</i> and <i>fusobacterium nucleatum.</i> <b>Disclosure:</b> Dr. Hackmyer has nothing to disclose. Dr. Ko has nothing to disclose. Dr. Hanrahan has received personal compensation for serving as an employee of Nowyouknow Neuro.

Local percolation of non-spherical particles in moving bed waste heat recovery unit for hydrogen production by methanol steam reforming

To study the local percolation of non-spherical particles in a moving bed waste heat recovery unit (MBWHRU) for hydrogen production, the discrete element method (DEM) was applied to simulate the discharge. A local method was applied to determine the location and local intensity of percolation. The percolation maps were presented. Moreover, the effects of structural parameters of MBWHRU, fine particle parameters, and friction parameters on local percolation were also considered. Percolation mainly occurs at the bottom, flow mechanism transition region, and near the vertical segment wall. Among them, percolation above the orifice is the most intense. The velocity gradient (or shear) is not the only condition under which percolation occurs. Percolation is closely related to changes in multiple parameters. The effects of fine particle parameters and friction parameters relative to structural parameters on percolation are significant. Percolation can be effectively avoided by increasing the mass percentage and particle size of fine particles, which is beneficial to hydrogen production. Especially, for the particle size ratio of fine particles to coarse particles greater than 0.5, percolation is no longer evident. The percolation near the vertical segment wall is particularly sensitive to particle-wall friction (>0.45). Reducing particle-particle friction and wall roughness is also beneficial to hydrogen production.

Study on vertical line source Green's function for hydrodynamic calculations of ocean structures in water with ice cover

The numerical calculation of panel integrals associated with the Green's function satisfying water surface condition with ice cover is the basis for the boundary element method (BEM) to solve hydrodynamic problems of ocean structures in ice regions. In order to simplify the calculation process and reduce the time consuming, the vertical line source representing the analytical integral of ice-covered Green's function over vertical line segment is firstly derived in this paper. Then a semi-analytical quadrature, which accumulates a series of vertical line sources distributing along the horizontal direction, can be derived for the panel integral. In the numerical implementation, the asymptotic analysis method is employed to eliminate the singularity at zero point of the denominator, variable substitution is performed to treat the integral at infinite and approximate polynomials are introduced to evaluate the Bessel functions. Through the calculations of vertical line and panel integrals of Green's function and its derivatives, the analytical expression of vertical line source is proved to be accurate and more efficient than the normal numerical quadrature. Based on this, a BEM program is developed and applied in the hydrodynamic calculations of submerged structures with ice cover. The computed results are found to be in excellent agreement those of the validated BEM based on point source, which further verifies the reliability and practicability of utilization of vertical line source.

Computing Bend-Minimum Orthogonal Drawings of Plane Series–Parallel Graphs in Linear Time

AbstractA planar orthogonal drawing of a planar 4-graph G (i.e., a planar graph with vertex-degree at most four) is a crossing-free drawing that maps each vertex of G to a distinct point of the plane and each edge of G to a polygonal chain consisting of horizontal and vertical segments. A longstanding open question in Graph Drawing, dating back over 30 years, is whether there exists a linear-time algorithm to compute an orthogonal drawing of a plane 4-graph with the minimum number of bends. The term “plane” indicates that the input graph comes together with a planar embedding, which must be preserved by the drawing (i.e., the drawing must have the same set of faces as the input graph). In this paper we positively answer the question above for the widely-studied class of series–parallel graphs. Our linear-time algorithm is based on a characterization of the planar series–parallel graphs that admit an orthogonal drawing without bends. This characterization is given in terms of the orthogonal spirality that each type of triconnected component of the graph can take; the orthogonal spirality of a component measures how much that component is “rolled-up” in an orthogonal drawing of the graph.

Aesthetic Genioplasty Based on Strategic Categorization.

Genioplasty is a popular procedure used for lower facial contour correction. Various osteotomy techniques enable us to perform advancement, setback, reduction, or narrowing procedures. Computed tomographic images facilitate preoperative planning in detail. The authors used a novel planning method based on strategic categorization. The analytic results are described. This retrospective study reviewed 208 patients who underwent genioplasty procedures for facial contouring from October of 2015 to April of 2020. During preoperative evaluation of the mandible, the operative procedure selected was one of three types: (1) horizontal segment osteotomy, (2) vertical and horizontal segment osteotomy, and (3) bone graft after repositioning. Adequate osteotomies were followed by rigid fixation using a titanium plate and screws. The follow-up period ranged from 8 to 24 months (average, 17 months). The results were assessed based on medical records, photographs, and facial bone computed tomographic images. Overall, the patients were satisfied with the outcomes and had responder-based improvement in lower facial contour and balance. Chin point deviations were noted in 176 cases; left-side deviation ( n = 135) was more frequent than right-side deviation ( n = 41). Strategic osteotomies based on precise measurements led to correction of asymmetries. Temporary partial sensory losses reported in 12 cases resolved within an average of 6 months after surgery. Each patient's chief complaint and bony structures should be carefully evaluated before genioplasty procedures are performed. During the operation, meticulous osteotomy, precise movement, and rigid fixation are necessary. The strategic process used for genioplasty resulted in aesthetic balance and predictable outcomes. Therapeutic, IV.

Underwater oscillations of rigid plates with H-shaped cross sections: An experimental study to explore their flow physics

In this work, we present a comprehensive experimental study on the problem of harmonic oscillations of rigid plates with H-shaped cross sections submerged in a quiescent, Newtonian, incompressible, viscous fluid environment. Motivated by recent results on the minimization of hydrodynamic damping for transversely oscillating flat plates, we conduct a detailed qualitative and quantitative experimental investigation of the flow physics created by the presence of the flanges, that is, the vertical segments in the plate cross section. Specifically, the main goal is to elucidate the effect of flange size on various aspects of fluid–structure interaction, by primarily investigating the dynamics of vortex shedding and convection. We perform particle image velocimetry experiments over a broad range of oscillation amplitudes, frequencies, and flange size-to-width ratios by leveraging the identification of pathlines, vortex shedding and dynamics, distinctive hydrodynamic regimes, and steady streaming. The fundamental contributions of this work include novel hydrodynamic regime phase diagrams demonstrating the effect of flange ratio on regime transitions, and in the investigation of their relation to qualitatively distinct patterns of vortex–vortex and vortex–structure interactions. Finally, we discuss steady streaming, identifying primary, and secondary structures as a function of the governing parameters.

Guest Editorial: 5G Advanced

3GPP specified 5G and provided improvements in terms of the system performance and support for the integration of new scenarios for accommodating various vertical segments. The upcoming Release 18 defines “5G Advanced” as a milestone towards 6G, introducing several enhancements in terms of the network architecture, physical layer, new services, security, and automation.

A turbulence data reduction scheme for autonomous and expendable profiling floats

Abstract. Autonomous and expendable profiling-float arrays such as those deployed in the Argo Program require the transmission of reliable data from remote sites. However, existing satellite data transfer rates preclude complete transmission of rapidly sampled turbulence measurements. It is therefore necessary to reduce turbulence data on board. Here we propose a scheme for onboard data reduction and test it with existing turbulence data obtained with a modified SOLO-II profiling float. First, voltage spectra are derived from shear probe and fast-thermistor signals. Then, we focus on a fixed-frequency band that we know to be unaffected by vibrations and that approximately corresponds to a wavenumber band of 5–25 cpm. Over the fixed-frequency band, we make simple power law fits that – after calibration and correction in post-processing – yield values for the turbulent kinetic energy dissipation rate ϵ and thermal-variance dissipation rate χ. With roughly 1 m vertical segments, this scheme reduces the necessary data transfer volume 300-fold to approximately 2.5 kB for every 100 m of a profile (when profiling at 0.2 m s−1). As a test, we apply our scheme to a dataset comprising 650 profiles and compare its output to that from our standard turbulence-processing algorithm. For ϵ, values from the two approaches agree within a factor of 2 87 % of the time; for χ, they agree 78 % of the time. These levels of agreement are greater than or comparable to that between the ϵ and χ values derived from two shear probes and two fast thermistors, respectively, on the same profiler.