General Plane Research Articles

Steady Generalized Plane Couette Flow of Viscous Incompressible Fluid between Two Porous Parallel Plates through Porous Medium with Magnetic Field

In this paper, we have investigated the steady generalized plane Couette flow of viscous incompressible fluid between two porous parallel plates through porous medium with magnetic field. We have studied the velocity, average velocity, shear stress, skin frictions, the volumetric flow, drag coefficients & stream lines.

FKT is Not Universal \u2014 A Planar Holant Dichotomyfor Symmetric Constraints

We prove a complexity classification for Holant problems defined by an arbitrary set of complex-valued symmetric constraint functions on Boolean variables. This is to specifically answer the question: Is the Fisher-Kasteleyn-Temperley (FKT) algorithm under a holographic transformation (Valiant, SIAM J. Comput. 37(5), 1565–1594 2008) a universal strategy to obtain polynomial-time algorithms for problems over planar graphs that are intractable on general graphs? There are problems that are #P-hard on general graphs but polynomial-time solvable on planar graphs. For spin systems (Kowalczyk 2010) and counting constraint satisfaction problems (#CSP) (Guo and Williams, J. Comput. Syst. Sci. 107, 1–27 2020), a recurring theme has emerged that a holographic reduction to FKT precisely captures these problems. Surprisingly, for Holant, we discover new planar tractable problems that are not expressible by a holographic reduction to FKT. In particular, a straightforward formulation of a dichotomy for planar Holant problems along the above recurring theme is false. A dichotomy theorem for #CSPd, which denotes #CSP where every variable appears a multiple of d times, has been an important tool in previous work. However the proof for the #CSPd dichotomy violates planarity, and it does not generalize to the planar case easily. In fact, due to our newly discovered tractable problems, the putative form of a planar #CSPd dichotomy is false when d ≥ 5. Nevertheless, we prove a dichotomy for planar #CSP2. In this case, the putative form of the dichotomy is true. (This is presented in Part II of the paper.) We manage to prove the planar Holant dichotomy relying only on this planar #CSP2 dichotomy, without resorting to a more general planar #CSPd dichotomy for d ≥ 3. A special case of the new polynomial-time computable problems is counting perfect matchings (#PM) over k-uniform hypergraphs when the incidence graph is planar and k ≥ 5. The same problem is #P-hard when k = 3 or k = 4, which is also a consequence of our dichotomy. When k = 2, it becomes #PM over planar graphs and is tractable again. More generally, over hypergraphs with specified hyperedge sizes and the same planarity assumption, #PM is polynomial-time computable if the greatest common divisor (gcd) of all hyperedge sizes is at least 5. It is worth noting that it is the gcd, and not a bound on hyperedge sizes, that is the criterion for tractability.

You Don’t Fool Me: On Scams, Scambaiting, Deception, and Epistemological Ambiguity at R/scambait on Reddit

With a focus on the online phenomena of scamming and scambaiting, this article explores users’ communicative activities on Reddit’s r/scambait subreddit. Drawing on a representative corpus viewed through grounded theory, we establish the basic categories of posts and then unpack those further to reveal the deceptive practices being undertaken by both scammers and scambaiters, as well as Redditors’ untruthfulness in their fabricated posts. The analysis reveals that the r/scambait subreddit exists as a site of humorous entertainment arising from various forms of deception. Scammers’ deceptive strategies are depicted as amusingly naïve and inefficient, while scambaiters’ deceptive messages targeted at scammers demonstrate great creativity and wittiness. In both cases, scammer-victims are disparaged for being immensely gullible or downright stupid; and Redditors earn online plaudits for submitting the most upvoted posts. Our significant finding is that posts such as those at r/scambait should never be taken at face value due to their inherent epistemological ambiguity, to which the users choose to remain oblivious or indifferent. Furthermore, on a general plane, this study indicates a potential shift in the emic understanding of the concept of “scambaiting” from a punitive measure and an educational instrument to a creative practice geared toward posters’ kudos and users’ joint humorous experience through “baitertainment” and “scamusement.”

Understanding the Structure‐Activity Relationship of Ni‐Catalyzed Amide C−N Bond Activation using Distortion/Interaction Analysis

AbstractTransition metal‐catalyzed amide C−N bond activation has emerged as a powerful strategy to utilize amides in synthetic transformations. The key mechanistic basis for the rational design of amide reagents is the structure‐activity relationship of amide C−N bond activation. In this work, the controlling factors of Ni/PCy3‐catalyzed amide C−N bond activation barrier are elucidated with density functional theory (DFT) calculations and distortion/interaction analysis. We found that the substrate distortion is the key factor that differentiates the amide reactivity in the C−N bond activation. The substrate distortion of amide is associated with two distinctive structure‐activity relationships. The general planar amides undergo a classic three‐membered ring oxidative addition to cleave the C−N bond, in which the C−N heterolytic bond dissociation energy has a linear relationship with the activation barrier. The twisted amides have a chelation‐assisted transition state for the amide C−N bond cleavage, and the twisted angle τ can serve as a predictive parameter for the reactivity of the twisted amides. The understanding of the structure‐activity relationship of amide C−N bond activation provides a rational and predictive basis for future reaction designs involving transition metal‐catalyzed amide C−N bond activation.

Study on the nonreciprocal absorption properties of cylindrical photonic crystals embedded in graphene cascaded by periodic and Rudin–Shapiro sequences at large incident angles

Using the transfer matrix method, the absorption, reflection, and nonreciprocity of the cylindrical photonic crystals (CPCs) consisting of graphene and two layers of ordinary medium cascaded by a periodic sequence and a Rudin–Shapiro quasiperiodic sequence are investigated under a large incidence angle of electromagnetic wave. By comparing the cascade of two periodic structures and the case of a single periodic structure, it is concluded that the structure proposed in this paper has better nonreciprocal phenomena and wider relative absorption bandwidth at a large incidence angle, reaching 162.2%, which is also much higher than the general planar photonic crystals. The absorption performance of this structure in TE and TM modes is compared at different angles and it is found that TM mode has a wider absorption bandwidth and has an ideal bandwidth in a large range of incident angle from 20° to 80°. Meanwhile, the optimum parameters of chemical potential and medium thickness are discussed, which can meet the requirements of large absorption bandwidth and significant nonreciprocity at a large incident angle. The CPCs embedded in graphene adopted in this paper are structures that have never been studied before. The electrical conductivity of graphene can be adjusted by the chemical potential, which can more conveniently realize many optical phenomena and provide reference and application values for optical sensing, optical filtering, and optical detection.

Wearable Triboelectric Strain-Insensitive Pressure Sensors Based on Hierarchical Superposition Patterns.

Recently, wearable triboelectric sensors capable of self-powering, which can be widely used in artificial skin and robotics, have received much attention. Herein, we develop a stretchable triboelectric pressure sensor with a new pattern by superimposing two patterns using both polystyrene beads and UV-ozone treatment. This patterned structure works more sensitively to pressure than a general planar and one-kind patterned structure. The sensor is constructed by sandwiching styrene butadiene rubber (SBR) and poly(dimethylsiloxane) (PDMS). It demonstrates a high sensitivity of 0.078 kPa-1 (0-20 kPa), a low detection limit (1.2 kPa), and pressure sensitivity maintained under 40% strain. The detection behavior of the strain-insensitive triboelectric sensor against pressure is very consistent with the simulation based on the theory. In applications, we successfully detect various human motions, not only small motions such as bending fingers but also large motions such as standing up and raising arms.

Nanoscale 3D Printing of Quantum Dots on Paper

Nanoscale integration is difficult on rough surfaces despite their ubiquity and usefulness. Paper is an emerging material system because it is renewable, flexible, and lightweight. However, owing to the rough surface of paper, it is difficult to use conventional nanoscale integration methods. Herein, nanoscale printing of CdSe/ZnS quantum dots on paper using a 3D printing method with surface adaptive control of the femtoliter meniscus is demonstrated. The approach allows the direct integration of light‐emitting materials on the intact surface of paper with nanoscale lateral confinement. The 3D‐printed nanostructures can be treated as a planar pattern of the nanoscale dots when viewed from the top. The individually addressable nature of the 3D printing method enables the equalization of the printed heights, which is essential for practical use in general planar systems. This method can be used in many areas that require paper such as paper electronics, security printing, biomedical engineering, and possibly other material systems with rough surfaces.

Façade Cleaning Robot With Manipulating and Sensing Devices Equipped on a Gondola

Façade cleaning of high-rise buildings requires automation due to the risk and inefficiency of a fall accident for human workers. Recently, due to the need for automation, various types of façade cleaning robots have been developed. In our previous study, the gondola-mounted type cleaning robot was developed, and it showed several issues. In this article, we propose an improved design feature to solve the issues. First, we modularized the robot design for lightweight and maintainability. Second, we implemented passive obstacle overcoming mechanism with tri-star wheel and compliant manipulator for minimizing uncleaned area near obstacles. Third, we developed the position sensing device for measurement and compensation of lateral disturbance occurred by swinging gondola. To verify the cleaning performance of the robot, experiments were conducted with different scenarios of cleaning general plane surface, obstacle overcoming, and lateral disturbance applied and compensated. Experimental results of both lab test and field-test performed on a real-world building were analyzed and summarized in this article.

Hölder estimates for the ∂̄ problem for (p,q) forms on product domains

The purpose of this paper is to study Hölder estimates for the [Formula: see text] problem for [Formula: see text] forms on products of general planar domains. As indicated by an example of Stein and Kerzman, solutions to the [Formula: see text] problem on product domains in [Formula: see text] does not gain regularity in Hölder spaces. Making use of an integral representation of Nijenhuis and Woolf, we show that given a [Formula: see text]-closed [Formula: see text] form with [Formula: see text] components, [Formula: see text], [Formula: see text], there is a [Formula: see text] solution to the [Formula: see text] problem on product domains for any [Formula: see text] with the desired Hölder estimate.

Ketamine versus neostigmine as adjuvants to bupivacaine during ultrasound-guided serratus anterior plane block in modified radical mastectomy. A randomized controlled trial

ABSTRACT Background: This study aims to investigate the analgesic efficacy of ketamine and neostigmine as adjuvants to local anesthetic in ultrasound-guided Serratus anterior plane block for patients undergoing Modified Radical Mastectomy. Methods: Ninety female patients aged 20–65 who were scheduled for a modified radical mastectomy under-combined general anesthesia and preoperative Serratus Anterior Plane Block were included. Three local anaesthetic mixtures were used, either 30 ml bupivacaine 0.25% + 1 ml ketamine (50 mg) (Group K) or 30 ml bupivacaine 0.25% + 1 ml neostigmine (500 μg) (Group N) or 30 ml bupivacaine 0.25% + 1 ml normal saline (Group S). The first 24 hours of postoperative morphine consumption was set as the primary outcome Results: the 24 hr postoperative morphine consumption median was 3.0 (0.0–9.0) for group (S), 1.5 (0.0–4.0) for group (N) and 0.0 (0.0–4.0) mg for group (K) with statistical significant (P value 0.045). The first postoperative analgesic request was insignificant between group (K), group (N) and group (S) was (6.14 ± 5.17), (6.67 ± 3.18) and (5.89 ± 4.4 hr), respectively. The Intraoperative Fentanyl consumption showed a significant reduction in group (N) and group (K) (111.67 ± 30.64 and 110.00 ± 20.34, respectively) compared to group (S) (131.67 ± 42.51 μg). The numerical rating scale did not differ between study groups except at 8th and 16th hrs. Postoperatively. Conclusion: The addition of 50 mg ketamine to 0.25% bupivacaine during preoperative ultrasound-guided SAPB combined with GA in female patients undergoing modified radical mastectomy decreased the 24 hr postoperative morphine consumption and the intraoperative fentanyl requirements while adding 500 µg neostigmine decreased the intraoperative fentanyl requirements. Clinical trial registration: The study was registered at clinicaltrials.gov (NCT 04544228).

Polar tangential angles and free elasticae

In this note we investigate the behavior of the polar tangential angle of a general plane curve, and in particular prove its monotonicity for certain curves of monotone curvature. As an application we give (non)existence results for an obstacle problem involving free elasticae.

Lattice Boltzmann Simulation of Plane Strain Problems

AbstractThe Lattice Boltzmann Method (LBM), e.g. in [3] and [4], can be interpreted as an alternative method for the numerical solution of partial differential equations. The LBM is usually applied to solve fluid flows. However, the interpretation of the LBM as a general numerical tool, allows to extend the LBM to solid mechanics as well. In this spirit, the LBM has been studied in recent years. First publications [5], [6] present a LBM scheme for the numerical solution of the dynamic behavior of a linear elastic solid under simplified deformation assumptions. For so‐called anti‐plane shear deformation, the only non‐zero displacement component is governed by the two‐dimensional wave equation. In this work, the existing LBM for the two‐dimensional wave equation is extended to more general plane strain problems. The algorithm reduces the plane strain problem to the solution of two separate wave equations for the volume dilatation and the non‐zero component of the rotation vector, respectively.

ІННОВАЦІЙНІ ЗВУКОВІ ТЕХНОЛОГІЇ ПРОСТОРОВОЇ ЗВУКОПЕРЕДАЧІ: РЕТРОСПЕКТИВА ЗВУКОВИХ ІНСТАЛЯЦІЙ

The purpose of the article is to determine the peculiarities of the development of the art of sound installation in the context of the concepts of acoustic space in the second half of the 20th – beginning of the 21st century. Research Methodology. The interdisciplinary methodology of critical spatial analysis and critical research in music has been applied to study the concepts of space and place, which became the basis for the practice of sound installation in the middle of the 20th century and the beginning of the 21st; systemic and evolutionary methods that have contributed to the consideration of the musical installation in the general philosophical and ontological plane in order to obtain the results useful in music and related sciences. Scientific Novelty. The peculiarities of the formation and development of the art of sound installation through the prism of the concepts of acoustic space of the second half of the 20th – beginning of the 21st century have been studied; for the first time in Ukrainian art studies, the essential foundations of sound installation are revealed in the context of the interpretation of the concept of a reflected sound object, alternative and extended concepts of space, in particular, the concept of space as a social production; the concepts of “spatial sound”, “spatial music” and “musical installation” have been considered; the means of sound ontology have been analysed in direct connection with the ontologies of space and place. Conclusions. The study has revealed that the concepts of acoustic space of the middle of the 20th century, based on the binary constructions male/female, rational/ irrational and Western/non-Western, in order to formulate the idea of acoustic space as sensual and chaotic, which arose for the perception of rational and ordering of visual space, represented a large project within the Western musical composition: the revival of rational, logical and objective as to the sounding. The use of sound as the main media contributes to the disclosure of the unique possibilities of the art of installation, organically combining the properties of space and place with the characteristics of sound and the specificity of human perception of its various attributes, offering an innovative relationship of acoustic space with its historical, social, narrative, tactile and physical qualities.

Lp bounds of maximal operators along variable planar curves in the Lipschitz regularity

In this paper, for general plane curves γ satisfying some suitable smoothness and curvature conditions, we obtain the single annulus Lp(R2)-boundedness of the Hilbert transforms HU,γ∞ along the variable plane curves (t,U(x1,x2)γ(t)) and the Lp(R2)-boundedness of the corresponding maximal functions MU,γ∞, where p>2 and U is a measurable function. The range on p is sharp. Furthermore, for 1<p≤2, under the additional conditions that U is Lipschitz and making a ε0-truncation with γ(2ε0)≤1/4‖U‖Lip, we also obtain similar boundedness for these two operators HU,γε0 and MU,γε0.

Comparison between Specialized Quadrature Rules for Method of Moments with NURBS Modelling Applied to Periodic Multilayer Structures

A comparison between Ma-Rokhlin-Wandzura (MRW) and double exponential (DE) quadrature rules for numerical integration of method of moments (MoM) matrix entries with singular behavior is presented for multilayer periodic structures. Non Uniform Rational B-Splines (NURBS) modelling of the layout surfaces is implemented to provide high-order description of the geometry. The comparison is carried out in order to show that quadrature rule is more suitable for MoM matrix computation in terms of sampling, accuracy of computation of MoM matrix, and CPU time consumption. The comparison of CPU time consumption shows that the numerical integration with MRW samples is roughly 15 times faster than that numerical integration using DE samples for results with similar accuracies. These promising results encourage to carry out a comparison with results obtained in previous works where a specialized approach for the specific analysis of split rings geometries was carried out. This previous approach uses spectral MoM version with specific entire domain basis function with edge singularities defined on split ring geometry. Thus, the previous approach provides accurate results with low CPU time consumption to be compared. The comparison shows that CPU time consumption obtained by MRW samples is similar to the CPU time consumption required by the previous work of specific analysis of split rings geometries. The fact that similar CPU time consumptions are obtained by MRW quadrature rules for modelling of general planar geometries and by the specialized approach for split ring geometry provides an assessment for the usage of the MRW quadrature rules and NURBS modelling. This fact provides an efficient tool for analysis of reflectarray elements with general planar layout geometries, which is suitable for reflectarray designs under local periodicity assumption where a huge number of periodic multilayer structures have to be analyzed.

БЕЗКОНТАКТНИЙ ЄМНІСНИЙ СЕНСОР СИСТЕМИ КОНТРОЛЮ ПАРАМЕТРІВ БИТТЯ ВАЛІВ ПОТУЖНИХ ЕЛЕКТРИЧНИХ МАШИН

In this paper presents the results of the definition the need to use a Kelvin guard ring to reduce the impact of external fields and non-uniformity of equipotential lines to change response characteristic of the capacitive sensor with a central high-potential electrode and a Kelvin guard ring. Measuring transducer placing in the immediate vicinity of the electrodes of the sensor, which eliminates the need to use a triaxial cable, was proposed. The sensor is designed to measure powerful generators shafts cylindrical surfaces parameters run-out. Capacitive sensor response characteristic function which depending on distance between the general plane of electrodes of the sensor and the grounded surface of a shaft is determined analytically and by computer simulation methods. The expediency of using computer modeling tools by finite element analysis methods for studying the metrological characteristics of sensors was shown. References 21, figures 4, table 1.

The Transition Between Reactive and Radiative Regimes for Leaky Modes in Planar Waveguides Based on Homogenized Partially Reflecting Surfaces

The gradual transition from a reactive to a radiative regime is studied for leaky modes supported by multilayered planar open waveguides. The so-called leaky cutoff condition, i.e., the frequency for which the leaky phase constant β equals the leaky attenuation constant α, originally introduced for microstrip lines and other printed structures, is investigated here with the aim of providing detailed information on the relative amount of reactive and radiative attenuation for leaky modes excited by finite sources and propagating as cylindrical waves along general planar waveguides. Analytical results are derived on the basis of a lossy parallel-plate-waveguide model and are validated through full-wave numerical simulations of 2-D leaky-wave structures based on grounded slabs covered with lossless or lossy partially reflecting surfaces (including, e.g., graphene layers) that can be treated as homogenized sheets. An analysis of the complex wave impedance of the considered leaky modes is also provided, in order to assess the frequency ranges where a good input matching can be expected for practical sources. In this regard, an ad hoc impedance matching network is designed and full-wave validated for a specific case to show that is indeed possible to achieve a good impedance matching below the cutoff in practical designs.

Generalization of Perfect Electromagnetic Conductor Boundary

Certain classes of electromagnetic boundaries satisfying linear and local boundary conditions can be defined in terms of the dispersion equation of waves matched to the boundary. A single plane wave is matched to the boundary when it satisfies the boundary conditions identically. The wave vector of a matched wave is a solution of a dispersion equation characteristic to the boundary. The equation is of the second order, in general. Conditions for the boundary are studied under which the dispersion equation is reduced to one of the first order or to an identity, whence it is satisfied for any wave vector of the plane wave. It is shown that, boundaries associated to a dispersion equation of the first order, form a natural generalization of the class of perfect electromagnetic conductor (PEMC) boundaries. As a consequence, the novel class is labeled as that of generalized perfect electromagnetic conductor (GPEMC) boundaries. As another case, boundaries for which there is no dispersion equation (NDE) for the matched wave (because it is an identity) are labeled as NDE boundaries. They are shown to be special cases of GPEMC boundaries. Reflection of the general plane wave from the GPEMC boundary is considered and an analytic expression for the reflection dyadic is found. Some numerical examples on its application are presented for visualization.

Adjoint optimization of pressurized membrane structures using automatic differentiation tools

This paper presents an adjoint-based method for solving optimization problems involving pressurized membrane structures subject to external pressure loads. Shape optimization of pressurized membranes is complicated by the fact that, lacking bending stiffness, their three-dimensional shape must be sustained by the internal pressure of the inflation medium. The proposed method treats the membrane structure as an immersed manifold and employs a total Lagrangian kinematic description with an analytical pressure–volume relationship for the inflating medium. To demonstrate the proposed method, this paper considers hydrostatically loaded inflatable barriers and develops an application-specific shape parametrization based on the analytical inhomogeneous solution for the inflated shape of cylindrical membranes. Coupling this shape parametrization approach with the adjoint method for computing the gradients of functionals enables a computationally efficient optimization of pressurized membrane structures. Numerical examples include minimization and minimax problems with inequality and state constraints, which are solved considering both plane strain and general plane stress conditions. The numerical implementation leverages the high-level mathematical syntax and automatic differentiation features of the finite-element library FEniCS and related library dolfin-adjoint. The overall techniques generalize to a broad range of structural optimization problems involving pressurized membrane and thin shell structures.

Defining technological features in the manufacture of semi-hard book covers

An experimentally determined list of the required and sufficient technological operations to produce semi-hard book covers has been proposed, with the calculated contour and structural design, which implies strict tolerances in the deviations from a rectangular planar geometry. It has been proven that the main features in the modeling and manufacturing of covers affect the conditions for ensuring tolerances, as well as stable circulation quantity. They imply that the edges and flaps as the additional structural elements of the covers form, after folding and gluing to the main part, a double composite structure. Due to this, there are no laps in the joints of edges and flaps, so the plane of the inner part of the covers acquires a flat shape, without defective contours. Therefore, one can argue that the parallel deviation of the outer contours of semi-hard covers from a rectangular design will not exceed the ranges for bookbinding divided into groups based on quality indicators. It should be particularly noted that the conditions for providing tolerances, circularity stability, as well as the composite structure of semi-hard covers, are influenced by the roller-roll mechanisms, which perform their rotary pressing and high-speed coordinated transportation during manufacturing. The current study into the effect exerted by the plastic deformation has established the mechanisms of the process of improving a cylindrical surface of the rotary-pressing rollers. It has been proven that they imply the formation of a completely regular microrelief of the hexagonal type with a concave shape and a partly regular micro-relief, in the form of the flat-parallel slotted recesses arranged at an angle to the central axis of the rollers. As well as the application of technology of the ionic nitriding of the obtained microrelief in the plasma of the helicon discharge. The final stage of strengthening a near-surface layer of the rollers with ionic nitriding in the plasma of the helicon discharge captures the maximum level of the increased durability of the near-surface layer. It fluctuates in the range of the ratio of the plane onto which a regular microrelief is partially applied to the general plane of the roller’s surface