The application of ceramic technology in spherical pipe joints

2017 ◽  
Vol 231 (8) ◽  
pp. 1078-1088
Author(s):  
Zhang Yong ◽  
Qi Bo ◽  
Sun Xinxin
Keyword(s):  
Abrasive Wear ◽  
Numerical Simulations ◽  
Ceramic Coating ◽  
Ceramic Technology ◽  
Extreme Conditions ◽  
Cold Welding ◽  
Seal Failure ◽  
Sealing Performance ◽  
Different Types ◽  
Pipe Joints

Spherical pipe joints are prone to cold welding and wear, which may lead to seal failure under extreme conditions. To solve this problem, the application of ceramic technology in the spherical pipe joints is discussed in this paper. Both numerical simulations and experiments were performed for different types of coating material and different coating thicknesses. The results have demonstrated that the application of a ceramic coating could improve the sealing performance of spherical pipe joints. However, the performance was even better when a fully ceramic cone was used instead. Under the same initial torque, the number of usage cycles was much higher for the fully ceramic cone than for the coated cone, and abrasive wear was very slight. The results are expected to serve as reference for improving the sealing performance of spherical pipe joints.

Scale-dependent merging of baroclinic vortices

1994 ◽  
Vol 264 ◽  
pp. 81-106 ◽  
Author(s):  
J. Verron ◽  
S. Valcke
Keyword(s):  
Numerical Simulations ◽  
Critical Point ◽  
Lower Layer ◽  
Interaction Mechanism ◽  
Competitive Effects ◽  
Different Types ◽  
Shape Effects ◽  
Baroclinic Vortices ◽  
The Relationship ◽  
Stratified Model

The influence of stratification on the merging of like-sign vortices of equal intensity and shape is investigated by numerical simulations in a quasi-geostrophic, two-layer stratified model. Two different types of vortices are considered: vortices defined as circular patches of uniform potential vorticity in the upper layer but no PV anomaly in the lower layer (referred to as PVI vortices), and vortices defined as circular patches of uniform relative vorticity in the upper layer but no motion in the lower layer (referred to as RVI vortices). In particular, it is found that, in the RVI case, the merging behaviour depends strongly on the magnitude of the stratification (i.e. the ratio of internal Rossby radius and vortex radius). The critical point here appears to be whether or not the initial eddies have a deep flow signature in terms of PV.The specific phenomenon of scale-dependent merging observed is interpreted in terms of the competitive effects of hetonic interaction and vortex shape. In the case of weaker stratification, the baroclinic structure of the eddies can be seen as dominated by a mechanism of hetonic interaction in which bottom flow appears to counteract the tendency of surface eddies to merge. In the case of larger stratification, the eddy interaction mechanism is shown to be barotropically dominated, although interface deformation still determines the actual eddy vorticity profile during the initialization stage. Repulsion (hetonic) effect therefore oppose attraction (barotropic shape) effects in a competitive process dependent on the relationship between the original eddy lengthscale and the first internal Rossby radius.A concluding discussion considers the implications of such analysis for real situations, in the ocean or in the laboratory.

Abrasive Wear Research on Rubber

1961 ◽  
Vol 34 (2) ◽  
pp. 482-492 ◽  
Author(s):  
K. Wellinger ◽  
H. Uetz
Keyword(s):  
Abrasive Wear ◽  
Abrasion Resistance ◽  
Testing Methods ◽  
Sand Blasting ◽  
Testing Conditions ◽  
Different Types ◽  
Paper Method ◽  
Abrasive Paper ◽  
Blasting Method

Abstract The abrasion resistance of five different types of rubber were compared with steel (St 37) by various testing methods, such as the abrasive paper method, the abrasion cup method and the sand blasting method. The order of resistance of the various types of rubber against sand blasting is different from the order which is obtained with the sandpaper and abrasion cup methods. However, variations of the testing conditions within one method generally does not change the order. It has been shown, that rubber is more resistant against sand blasting than other materials investigated (basalb, malleable steel, non-alloyed hard castings) if the sand blast is directed essentially perpendicularly against the tested surface.

Cold welding behavior of metallic glass nanowires: Insights from large-scale numerical simulations

2021 ◽  
Author(s):  
Yuhang Zhang ◽  
Jiejie Li ◽  
Hongjian Zhou ◽  
Yiqun Hu ◽  
Suhang Ding ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Numerical Simulations ◽  
Large Scale ◽  
Cold Welding

Amplitude Modulation and Symmetry Breaking Bifurcation in Micro Devices

2012 ◽  
Author(s):  
Z. C. Feng ◽  
Mahmoud Almasri
Keyword(s):  
Symmetry Breaking ◽  
Numerical Simulations ◽  
Amplitude Modulation ◽  
Dynamic Responses ◽  
Symmetric Structure ◽  
Different Types ◽  
Asymmetric Responses ◽  
Symmetric Response ◽  
Symmetry Breaking Bifurcation

Designs of many micro devices take advantage of the symmetry for better performance, immunity to noise, and for simpler analysis. When a symmetric structure is subjected to symmetric forcing, the symmetric response can become unstable leading to asymmetric responses. The occurrence of symmetry breaking bifurcation leads to complicated dynamic responses which often result in less desirable performances. In this paper, we obtain analytical criteria for the onset of symmetry breaking bifurcations. We also conduct numerical simulations to demonstrate different types of asymmetric dynamic responses resulting from the symmetry breaking bifurcation. In particular, we show the occurrence of amplitude modulated motions in such systems.

scholarly journals Epidermis structure in Mesembryanthemaceae

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 937-937
Author(s):  
H. -D. Ihlenfeldt
Keyword(s):  
Cell Walls ◽  
Climatic Conditions ◽  
Radiation Balance ◽  
Outer Cell ◽  
Extreme Conditions ◽  
Prominent Feature ◽  
Oxalate Crystals ◽  
Different Types ◽  
Bladder Cells ◽  
Epidermis Structure

The Mesembryanthemaceae, which inhabit the deserts and semi-deserts of Southern Africa, exhibit two very different types of epidermis. The first is characterized by thick outer cell walls encrusted by oxalate crystals, a thick cuticle and thick wax layers. In the second type, the epidermal cells exhibit only very thin outer cell walls, not encrusted by oxalate crystals, a very thin cuticle, and wax layers are poorly developed; the most prominent feature of this type is the occurrence of huge idioblasts often protruding as ‘bladder cells’. With regard to the climatic conditions in the native habitats this type of epidermis must be called ‘abnormal’. Both types of epidermis may form sculptures of three distinct size classes, which are not necessarily homologous. The function of these sculptures is still poorly understood. There is evidence that the sculptures influence the optical properties of the surfaces and thereby the radiation balance (and heat stress) of the leaves.From recent research, it has become evident that the two different types of epidermis are the anatomical expression of two different strategies for survival under extreme conditions. Species with the idioblast type of epidermis exhibit a strategy that might be called ‘opportunistic’. These species have developed a mechanism of gaining water from the atmosphere during the night under favourable conditions. There are indications that the idioblasts are involved in this mechanism.

Dynamics of Dual-Cell Series Miura-Ori Structures With Different Types of Inter-Cell Connections

2021 ◽  
Author(s):  
Hai Zhou ◽  
Haiping Wu ◽  
Jian Xu ◽  
Hongbin Fang
Keyword(s):  
Steady State ◽  
Numerical Simulations ◽  
Theoretical Basis ◽  
Initial Conditions ◽  
Cell Structure ◽  
Dynamic Responses ◽  
Complex Environment ◽  
Current State ◽  
Different Types ◽  
Cell Series

Abstract Origami-inspired structures and materials have shown remarkable properties and performances originating from the intricate geometries of folding. Origami folding could be a dynamic process and origami structures could possess rich dynamic characteristics under external excitations. However, the current state of dynamics of origami has mostly focused on the dynamics of a single cell. This research has performed numerical simulations on multi-stable dual-cell series Miura-Ori structures with different types of inter-cell connections based on a dynamic model that does not neglect in-plane mass. We introduce a concept of equivalent constraint stiffness k* to distinguish different types of inter-cell connections. Results of numerical simulations reveal the multi-stable dual-cell structure will exhibit a variety of complex nonlinear dynamic responses with the increasing of connection stiffness because of the deeper energy well it has. The connection stiffness has a strong effect on the steady-state dynamic responses under different excitation amplitudes and a variety of initial conditions. This effect makes us able to adjust the dynamic behaviors of dual-cell series Miura-Ori structure to our needs in a complex environment. Furthermore, the results of this research could provide us a theoretical basis for the dynamics of origami folding and serve as guidelines for designing dynamic applications of origami metastructures and metamaterials.

scholarly journals Monitoring of drilling conditions using the Hilbert-Huang transformation

2018 ◽  
Vol 148 ◽  
pp. 16003 ◽  
Author(s):  
Piotr Wolszczak ◽  
Grzegorz Litak ◽  
Marek Dziuba
Keyword(s):  
Fourier Transform ◽  
Numerical Simulations ◽  
Hilbert Transform ◽  
Geometrical Parameters ◽  
Drilling Process ◽  
Nonlinear Characteristics ◽  
Different Types ◽  
Fourier Spectra ◽  
Backbone Curves ◽  
Drilling Conditions

The article presents the results of design and monitoring the drilling process. Vibroacoustic sensors were used to observe spindle vibrations. These signals were subjected to a Huang decomposition and a Fourier transform. Results for various conditions were studied and classified with help of Fourier spectra and the envelope curves. Using the additional results of numerical simulations sources of vibration were identified. We considered four different types of drilling which were diversified in terms of geometrical parameters of blades. The application of Hilbert transform enable to find nonlinear characteristics via the deflection profile of resonance backbone curves.

scholarly journals Enhancing synchrony in multiplex network due to rewiring frequency

2019 ◽  
Vol 475 (2230) ◽  
pp. 20190460 ◽  
Author(s):  
Sarbendu Rakshit ◽  
Bidesh K. Bera ◽  
Jürgen Kurths ◽  
Dibakar Ghosh
Keyword(s):  
Numerical Simulations ◽  
Local Stability ◽  
Lorenz System ◽  
Stability Conditions ◽  
Network Architectures ◽  
Stability Function ◽  
Individual Layer ◽  
Multiplex Networks ◽  
Multiplex Network ◽  
Different Types

Most of the previous studies on synchrony in multiplex networks have been investigated using different types of intralayer network architectures which are either static or temporal. Effect of a temporal layer on intralayer synchrony in a multilayered network still remains elusive. In this paper, we discuss intralayer synchrony in a multiplex network consisting of static and temporal layers and how a temporal layer influences other static layers to enhance synchrony simultaneously. We analytically derive local stability conditions for intralayer synchrony based on the master stability function approach. The analytically derived results are illustrated by numerical simulations on up to five-layers multiplex networks with the paradigmatic Lorenz system as the node dynamics in each individual layer.

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