Circular Type Research Articles

The investigations of asperity peaks and surface roughness on transient squeeze elastohydrodynamic lubrication

Abstract The effects of asperity peak contact pressure and surface roughness (SRN) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts are investigated for fixed load by using Gauss-Seidel iteration method (GSIM) and finite difference method (FDM). The transient pressure, asperity peak contact pressure, elastic deformation, and film thickness during the pure squeeze process under distinct operating conditions in EHL regime are studied. The results indicate that the differences of the pressure and film thickness between SRNEHL model and EHL model are apparent in final stage due to elastic asperity peak contact. The asperity peak contact pressure will affect hydrodynamic pressure for fixed load, so the hydrodynamic pressure with roughness surface is smaller than that without roughness surface especially around the Hertzian contact (X=1) edge. These phenomena result in different changes in total pressure in different areas. For the contact region, the film thickness of smooth type (ST) is greater than those of circular roughness type (CRT), but this phenomenon reverses near X=1. The larger the C value, the earlier the asperity peak contact effect. Therefore, the greater the C values, the greater the asperity peak contact pressure, and the smaller the hydrodynamic pressure. The asperity peak contact effect significant changes many phenomena at contact region in squeezing final stage.

Response of circular type sandwich panel using JUCO-glass fiber with PU foam under three-point bending loading

In this study, a circular type honeycomb sandwich panel using natural JUCO and synthetic woven glass fiber was fabricated, and the bending properties like bending strength, modulus of rupture (MOR), and modulus of elasticity (MOE) were evaluated. Polyurethane (PU) foam was injected into the core structure to improve the bending strength. The orientation of jute and cotton fiber was varied to investigate the best stiffness and strength. In addition, twill-type JUCO fiber mat and synthetic woven glass fiber were also used to fabricate the circular type honeycomb sandwich panel. Finite element modeling was undertaken to validate the experimental results. Prior to the finite element analysis, a tensile test was carried out to determine the boundary conditions. Injecting polyurethane foam into the honeycomb core does not show any significant impact on bending properties. However, the deformation rate increased considerably by adding PU foam in the core structure. According to the results, honeycomb sandwich panels made of woven glass fiber with PU foam exhibited more homogenous deflection and bending compliance compared with others.

Design and Comparative Characterization of Water Level IDE Sensors at Resonant Frequencies

Background: This paper reports the design and characterization of three Interdigital electrode (IDE) water-level sensors at resonant frequencies. The geometries of the proposed IDE sensors are comb type, circular type, and Archimedean spiral type. These IDE sensors have been fabricated by the printed circuit board technology. The sensor’s performance has been evaluated on both tap and distilled water. Methods: The multiple resonant frequencies are investigated for the frequency span of 40 Hz to 110 MHz using a 4294A impedance analyzer. The peak of the projected admittance graph appeared at the first resonant frequency. This first resonant frequency is chosen here for the characterization of the proposed sensors. Results: The study asses that the variations in resonant frequency are caused by both the sensor's geometry and the water under test. The resonant frequency subtly states that sensors can be presented as lumped element equivalent series RLC circuits. In this work, an attempt has been made to show that the change in capacitance plays a pivotal role in estimating the resonant frequency. It is found that the sensor’s sensitivity decreases with water elevation and always be negative. Conclusion: The circular and Archimedean spiral sensors have comparable sensitivity performance, while the comb IDE sensor is found to be the most sensitive. The IDE sensor features the highest sensitivity at 1 cm of water elevation. The circular and spiral IDE sensor more closely follows the reference resonant frequency fr α 1/(√C) when compared with the comb IDE sensor.

The Effects of Controlling Gas Escape and Bottom Current Activity on the Evolution of Pockmarks in the Northwest of the Xisha Uplift, South China Sea

Submarine pockmarks are typical indicators of submarine gas escape activity. The deep strata of the Xisha Uplift are rich in biogenic and thermogenic gas, accompanied by strong bottom current activity. Investigating the effects of controlling submarine gas escape and bottom current activity on the formation and development of pockmarks in the Xisha Uplift is significant for understanding the evolution of submarine topography and geomorphology. This study utilized high-resolution multibeam data to identify 261 submarine pockmarks in the northwest of the Xisha Uplift. These pockmarks were categorized based on their morphology into circular, elliptical, elongated, crescent-shaped, and irregular types. The diameters of pockmarks in the study area range from 0.21 to 4.96 km, with maximum depths reaching 30.88 m. Using high-resolution multi-channel seismic data, we conducted a detailed analysis of the subsurface strata characteristics of the pockmarks, identifying chaotic weak reflections, bright spots, and high-angle reflectors. We believe that deep gas in the northwest of the Xisha Uplift escapes to the seafloor through migration pathways, such as faults, fractures, and gas chimneys, resulting in the formation of submarine pockmarks. Bottom current activity has a significant impact on already-formed pockmarks. Crescent-shaped and elongated pockmarks in the Xisha Uplift are largely the result of bottom current modifications of pre-existing pockmarks.

纵轴流玉米锥形脱粒装置优化设计与仿真分析

Aiming at the high crushing rate and impurity rate of corn kernel machine harvesting in the Huanghuaihai region, a longitudinal flow conical variable pitch threshing device is designed, which adopts the combined threshing element of "plate teeth + ribs" and the combined threshing concave plate of "leftward round tube type + vertical round tube type". The cob model was established, and the force analysis of the cob threshing process was carried out, and the type of threshing drum and the installation angle of the threshing concave plate round tube were determined as the main influencing factors, and the collision force on the corn cob was taken as the test index. Using EDEM discrete element simulation software, simulation tests were carried out on different types of threshing drums and threshing concave plates with different installation angles of round tubes with corn cobs, and the better threshing method was finally determined: a conical threshing drum at a drum speed of 450 r/min, and a combination of left-facing round-tube-type+vertical round-tube-type threshing concave plates with an installation angle of 10° (front-sparse and back-dense type) were used. Compared with the vertical circular tube type threshing concave plate, the corn cob contact force decreased from 313.5N to 247.3N, which was optimal for threshing in the range allowed by the corn kernel destructive force.

A New Decision Making Model Based on Complex Intuitionistic Fuzzy Soft Lattice for Traffic Monitoring in the Pandemic Scenarios

Various representations of real‐life scenarios by algebraic structures are of vital importance in the modern era of Industrial Revolution 4.0 as it enables such data to be interpreted and processed by artificial intelligence, thus bridging the interaction gap between humans and machines. In response to that, this article proposes a new decision making model for traffic control among shopping complexes utilizing the novel concept of the complex intuitionistic fuzzy soft lattice of the circular type (CIFSL‐C), which takes the time within a day as truly directional entities. As a result, CIFSL‐C possesses the combined structural complexity and the level of sophistication of all the previous algebraic models which they are derived from, enabling them to be utilized in representing many real‐life scenarios, including those related to the pandemic, which will be rigorously discussed in this article. In addition, the complex intuitionistic fuzzy soft lattice of the quaternion type (CIFSL‐Q) will also be established.

Six Business Model Types for Circular Building Component Reuse Actors

While circular business models are receiving increasing academic attention, the business models of real circular building companies remain underexamined. This paper builds upon existing conceptual proposals and general overviews of reuse actors to investigate how these organizations capture and create value within the constraints of the marketplace. Using data from case studies of 25 organizations involved in the reuse of construction waste streams, the business model of each case is described and compared using Osterwalder and Pigneur’s Business Model Canvas. The authors propose six categories of circular construction business model types: upcyclers, component-specific suppliers, material resellers, reuse platforms, reuse consulting offices and deconstruction companies. The key findings include the studied organizations’ consolidation of multiple waste and new product streams, the strategic minimization of hard assets, the cultivation of diverse revenue streams and an emphasis on private market solutions.

Compact Ultra Wide band Modified Circular Robo type Antenna for C – V2X application

This document focuses on the Ultra-Wideband Modified Circular Robo structure Antenna (UWCRSA) with partial ground for the sub-7 GHz band (4.17 GHz to 7 GHz). The overall geometry of the proposed antenna is 12×18×0.8 mm3. The designed structure is obtained by placing a simple modified circular robotic structure patch with dielectric constant (ɛr) and dissipation factor (tanδ) of 4.4 and 0.02, respectively, on the FR4 substrate. In this document, we examine the design technique, complexity, overall geometric parameters, substrate used, feed technique and performance analysis of the proposed antenna. The semi-grounded radiating patch design is primarily suitable for cellular vehicle applications and anything below 7 GHz (C – V2X) (IEEE 802.11p standard) and WIFI enhanced 3rd version (IEEE 802.11ac standard). Simulation results for the proposed antenna were generated with a Radio Frequency Structure Simulator (HFSS) and measurements were obtained with a Rohde and Schwarz ZNB 20 network analyzer. Simulation and measurement results are measured in terms of S11, VSWR, bandwidth, gain, directivity, efficiency and radiation pattern. Antenna results show good agreement and can be used for C – V2X, WIFI Extended 3rd Version and satellite communications.

The Truncated Moment Problem on Reducible Cubic Curves I: Parabolic and Circular Type Relations

In this article we study the bivariate truncated moment problem (TMP) of degree 2k on reducible cubic curves. First we show that every such TMP is equivalent after applying an affine linear transformation to one of 8 canonical forms of the curve. The case of the union of three parallel lines was solved in Zalar (Linear Algebra Appl 649:186–239, 2022. https://doi.org/10.1016/j.laa.2022.05.008), while the degree 6 cases in Yoo (Integral Equ Oper Theory 88:45–63, 2017). Second we characterize in terms of concrete numerical conditions the existence of the solution to the TMP on two of the remaining cases concretely, i.e., a union of a line and a circle y(ay+x2+y2)=0,a∈R\\{0}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$y(ay+x^2+y^2)=0, a\\in {\\mathbb {R}}{\\setminus } \\{0\\}$$\\end{document}, and a union of a line and a parabola y(x-y2)=0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$y(x-y^2)=0$$\\end{document}. In both cases we also determine the number of atoms in a minimal representing measure.

Characterizations of Finite Order Solutions of Circular Type Partial Differential-Difference Equations in $$ \mathbb {C}^n $$

Characterizations of Finite Order Solutions of Circular Type Partial Differential-Difference Equations in $$ \mathbb {C}^n $$

Spatio-Temporal Prediction of Three-Dimensional Stability of Highway Shallow Landslide in Southeast Tibet Based on TRIGRS and Scoops3D Coupling Model

National Highway G559 is the first highway in Southeast Tibet into Motuo County, which has not only greatly improved the difficult situation of local roads, but also promoted the economic development of Tibet. However, rainfall-induced shallow landslides occur frequently along the Bomi–Motuo section, which seriously affects the safe operation and construction work of the highway. Therefore, it is urgent to carry out geological disaster assessment and zoning along the highway. Based on remote-sensing interpretation and field investigation, the distribution characteristics and sliding-prone rock mass of shallow landslides along the Bomi–Motuo Highway were identified. Three-dimensional stability analysis of regional landslides along the Bomi-Motuo Highway under different rainfall scenarios was carried out based on the TRIGRS and Scoops3D coupled model (T-S model). The temporal and spatial distribution of potential rainfall landslides in this area is effectively predicted, and the reliability of the predicted results is also evaluated. The results show that: (1) The slope structure along the highway is mainly composed of loose gravel soil on the upper part and a strong weathering layer of bedrock on the lower part. The sliding surface is mostly a circular and plane type, and the main failure types are creep–tensile failure and flexural–tensile failure. (2) Based on the T-S coupling model, it is predicted that the potential landslide along the Bomi–Motuo Highway in the natural state is scattered. The distribution area of extremely unstable and unstable areas accounts for 4.92% of the total area. In the case of extreme rainfall once in a hundred years, the proportion of instability area (Fs < 1) predicted by the T-S coupling model 1 h after rainfall is 7.74%, which is 1.57 times that of the natural instability area. The instability area (Fs < 1) accounted for 43.40% of the total area after 12 h of rainfall. The potential landslides were mainly distributed in the Bangxin–Zhamu section and the East Gedang section. (3) The TRIGRS and T-S coupling model is both suitable for predicting the temporal–spatial distribution of rainfall-induced shallow landslides, but the TRIGRS model has the problem of over-prediction. The instability area predicted by the T-S coupling model accounted for 43.30%, and 74% of the historical landslide disaster points in the area were correctly predicted. (4) In terms of rainfall response, the T-S coupling model shows higher sensitivity. The %LRclass (Fs < 1) index of the T-S coupling model is above 50% in different time periods, and its landslide-prediction effect (%LRclass = 78.80%) was significantly better than that of the one-dimensional TRIGRS model (%LRclass = 45.50%) under a 12 h rainfall scenario. The research results have important reference significance for risk identification and disaster reduction along the G559 Bomi–Motuo Highway.

Hydraulic performance of bottom intake velocity caps using PIV and OpenFOAM methods

The objective of this investigation is to obtain a more profound understanding of the effective parameters of the velocity caps for bottom intake systems, utilizing particle image velocimetry (PIV) and OpenFOAM. Observations indicate a higher probability of surface vortex formation in square types compared to circular ones, with the vortex being formed downstream of the caps. Additionally, the flow pattern reveals that the flow whirls in a more favorable path into the circular caps as opposed to the square ones. Through both experimental and numerical comparisons of three shapes (rhombus, square, and circle), it becomes evident that the circular type outperforms the other types in terms of discharges through the intake, showing an improvement of about 8%. The results indicate that flow depth and height of the velocity caps are positively effective parameters for the flow rate, with respective influences of 90% and 30%. In contrast, the interaction between the flow and caps intensifies with an increase in the distance of the intake opening from the bed, which plays a negative influence on the flow rate. Enhancing the number of blades in caps proves to be the optimal approach for generating a smoother flow with minimal impact on the flow rate. Numerical simulations show a 50% reduction in cap height leads to a significant 33% decrease in flow rate. Additionally, rotating the square cap by 45° into a rhombus aligned with the flow direction results in a 7% discharge flow rate increase.

Circ_FNDC3B Promotes Cell Proliferation and Metastasis in Esophageal Squamous Cell Carcinoma via Regulating MAPK1 by Binding to miR-136-5p.

A handful of circular RNAs (circRNAs) associated with cancer progression have been indicated in esophageal squamous cell carcinoma (ESCC). The current study aimed to investigate the functional mechanism of circular RNA Fibronectin type III domain containing 3B (circ_FNDC3B) in ESCC. Circ_FNDC3B, FNDC3B, microRNA-136-5p (miR-136-5p) and mitogen-activated protein kinase 1 (MAPK1) were examined via the quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was evaluated by Cell Counting Kit-8 (CCK-8) and colony formation assays. Transwell assay was performed to measure cell migration and invasion. Protein analysis was implemented by western blot. Cell apoptosis was assessed via flow cytometry. Target interaction was affirmed using dual-luciferase reporter assay. The function analysis of circ_FNDC3B in vivo was explored by xenograft models. The upregulation of circ_FNDC3B was detected in ESCC tissues and cells. Functionally, ESCC cell proliferation and metastasis were repressed but apoptosis was promoted by circ_FNDC3B knockdown. Besides, circ_FNDC3B silence inhibited ESCC progression through MAPK1 downregulation. Further target analysis identified miR-136-5p as a target of circ_FNDC3B and an upstream control of MAPK1. Additionally, the regulation of si-circ_FNDC3B in ESCC was also dependent on targeting miR-136-5p. Moreover, circ_FNDC3B targeted miR-136-5p to affect MAPK1 level. Tumorigenesis in vivo was also suppressed by downregulating circ_FNDC3B to regulate miR-136-5p/MAPK1 axis. Circ_FNDC3B downregulation impeded the development of ESCC via the mediation of miR-136-5p/MAPK1 axis. This report afforded a novel insight into the functional mechanism of circ_FNDC3B in ESCC.

Analysis of the effectiveness of landslide stabilization in a near-dam reservoir area

The geological conditions of the landslide area in a near-dam reservoir area of a water conservancy hub project are complicated, and the stability problem of the landslide body is prominent, which is not only directly related to the safety of the adjacent office building and highway, but also poses a threat to the normal operation of the water conservancy hub. According to the latest geological data of the landslide area, the results of the stability calculation of the landslide body are analyzed, and the reinforcement design scheme of circular chair type anti-slide piles & prestressed anchor cables is proposed for the landslide body to solve the problem of anti-slide stability of the landslide body. Numerical analysis results show that: the safety factor under each working condition after reinforcement is within the permissible range and meets the relevant normative requirements, the landslide body has good control effect on deformation after reinforcement, and the reinforcement measures can provide certain reference value for the design and construction of similar projects.

Performance analysis and effect of various material fin-perforations in a plate-finned heat exchanger

Finding increasingly efficient heat exchangers requires a critical task: the development of fin profiles for prolonged life of equipment. The present study uses numerical analysis for better plate-finned heat exchangers hydraulic and thermal performance. Fin patterns are used in the analysis to evaluate a four-tube in-line heat exchanger. The proposed approach involves use of simulation and numerical methods to solve the heat transfer problem on different materials and wind velocity data as boundary conditions for improved heat transfer. The Reynolds-Averaged Navier-Stokes (RANS) model will be used to correct the average turbulent air flow over finned tubes in three dimensions using the ANSYS-Fluent software. The evaluation plan compares the current findings with published Nusselt number empirical correlations for the justification. Finally, the presentation of a parametric study on the impact of fin perforation size and shape on different materials and the behaviour of fluid dynamics and heat transfer. Larger fin perforation sizes (circular, rectangle, rhombus, and ellipse shapes) are found to enhance the heat exchangers' overall PEC and thermal efficiency for sustainability of the thermal equipment. The comparison was made between non-perforated and perforated fin types. Ultimately, it was determined that the best option for plate fin heat exchangers is the circular type perforated fin. When compared to without perforated fins, the circular type perforated fin has a higher heat transfer coefficient. A circular perforated fin has high performance, and the rhombus type perforated fin has lower performance.

Особенности архитектуры ленинградских хлебозаводов эпохи советского авангарда

The study examines the architectural features of 2 types of Leningrad bakeries of linear and circular type of conveyor systems of the Soviet avant-garde era. The author describes the stages of development and prerequisites for the creation of a new typology that meet the emerging specificity of New Soviet Life in post-revolutionary Russia. The phenomenon of the bakery as a new type of building and form system is a visual form of demonstration of constructivist solutions in avant-garde architecture. The article analyzes the stylistic features of Leningrad architectural school, which was influenced by the suprematist method of shaping. The features of the three-dimensional composition of buildings and the means of artistic expression characteristic of avant-garde architecture are revealed. As a result of the comparative analysis, it was concluded that Leningrad bakeries, having individual features, nevertheless harmoniously fit into the global architectural context.

Use of Simple Skull Radiographs in Orbital Correlations in Nigeria

Introduction: Anthropometric measurements have been carried out in many studies to segregate people into races, ethnicity and various biological traits in the past. Such studies include cephalometry being deployed because of its significance in forensic and clinical evaluations of individuals. The objective of this study is to determine the correlation between the shape types of the orbit with different age groups and their prevalence using simple skull X-rays.
 Materials and Methods: Plain X-rays of the skull with posteroanterior exposures were obtained for a retrospective period of 5-year period from 2004 to 2009. The selected radiographs were those based on clear recognition of their orbital margins assessed by 2 experienced Radiologist who determined the shapes of the orbits as being oval, circular or quadrangular. Out of total of five hundred (500) plain X-rays of the skull obtained, only 255 satisfied the inclusion criteria.
 The data was analyzed statistically using INSTAT software to compare the mean values in relation to age distribution of the subjects with the Student’s T-Test. Chi-Square (with Yates correction) was used for the comparison of proportions.
 Results: In the first 30 years of postnatal life, the oval shape orbit had been found to be more predominant with values of 22(64.7%), 17(30.9%), and 27(38.0%) respectively. As from the age of 30 to 70 years, the circular type had values of 16(34.0%), 8(33.3%), and 8(61.5%) respectively in each of the decades. Between the age of 60 to 70 years, the oval and circular types had equal prevalences.
 Conclusions: In addition to the known oval and quadrangular (triangular) types of orbital shape, this study revealed a 3rd type of orbit which we described as circular in shaped. The oval type of orbit is found to be more common from birth to age of 30 years but from but from 40 to 70 years the circular type predominates.

Experimental and Numerical Analysis of the Stress State Produced by a Circular Hole Concentrator

The paper proposes the analysis of strain and stress state, through experimental and numerical means, of a circular hole type concentrator. The strain state is analyzed through the microscopic Digital Image Correlation technique, due to the small scale of the samples, whose calibrated region is 10x8 mm. The numerical analysis is conducted using the Finite Element Method, through a static structural analysis, using a linear-elastic material model. The results from the two procedures are compared by means of strain field distribution around the stress concentrator and stress variation at the concentrator peak cross section. For validation, the analytical gross stress concentrator of the problem is used as baseline, Ktg. The results show that accurate reading can be achieved on this small scale. Additionally, the experimental method has also successfully identified crack initiations and propagations on the tested samples, significantly smaller than 1 mm, which can reveal future fracture mechanics analysis and supply data to models adapted to microscopic scale phenomena.

Time-Optimal Problem in the Roto-Translation Group with Admissible Control in a Circular Sector

We study a time-optimal problem in the roto-translation group with admissible control in a circular sector. The problem reveals the trajectories of a car model that can move forward on a plane and turn with a given minimum turning radius. Our work generalizes the sub-Riemannian problem by adding a restriction on the velocity vector to lie in a circular sector. The sub-Riemannian problem is given by a special case when the sector is the full disc. The trajectories of the system are applicable in image processing to detect salient lines. We study the local and global controllability of the system and the existence of a solution for given arbitrary boundary conditions. In a general case of the sector opening angle, the system is globally but not small-time locally controllable. We show that when the angle is obtuse, a solution exists for any boundary conditions, and when the angle is reflex, a solution does not exist for some boundary conditions. We apply the Pontryagin maximum principle and derive a Hamiltonian system for extremals. Analyzing a phase portrait of the Hamiltonian system, we introduce the rectified coordinates and obtain an explicit expression for the extremals in Jacobi elliptic functions. We show that abnormal extremals are of circular type, and they correspond to motions of a car along circular arcs of minimal possible radius. The normal extremals in a general case are given by concatenation of segments of sub-Riemannian geodesics in SE2 and arcs of circular extremals. We show that, in a general case, the vertical (momentum) part of the extremals is periodic. We partially study the optimality of the extremals and provide estimates for the cut time in terms of the period of the vertical part.

The Japanese Circular Economy and Sound Material-Cycle Society Policies: Discourse and Policy Analysis

Although the Japanese government is an early adopter of Circular Economy (CE) policies and developed the concept of the Sound Material-Cycle Society in the early 2000s, its CE policies have nonetheless been poorly researched and understood, especially in English academic literature. This article addresses this research gap by answering the following questions: What are the dominant discourses of key stakeholders in Japan regarding CE? And to what extent does the current CE policy in Japan relate to that? Methodologically, this paper conducted a discourse analysis through a mix of policy analysis, media analysis, stakeholder interviews, keyword mining, qualitative content analysis, and analysis of stakeholder presence. Results show that, while CE discourses in Japan are rather diverse, they mostly fall within the Reformist Circular Society discourse type, with some smaller Technocentric Circular Economy and Transformational Circular Society elements. Results also show that businesses and academics were over-represented in policy meetings and the media, compared to NGOs and local government actors, which are more likely to hold transformational circularity discourses. Most circularity discourses in Japan are thus focused on a growth-optimistic narrative that emphasises innovative technologies and lacks a stronger understanding of social justice and planetary boundaries. Based on these findings, this article suggests recommendations, such as revisiting Japanese ecological thinking and Buddhist philosophy, which can inspire degrowth-oriented circularity approaches, as well as encompassing more participation of neglected societal groups in the development and implementation of CE policies and practices. By highlighting the challenges in current CE discourse and implementation in Japan, this study presents implications for a more socially inclusive and ecologically sustainable path towards a circular society.