Continuous-Contact Operations

Keyword(s):  
Alloy Digest ◽  
1986 ◽  
Vol 35 (4) ◽  

Abstract ELECTROLESS NICKEL is a nickel coating deposited by chemical reduction of nickel ions. The most widely used reducing agent is sodium hypophosphite. The thickness of the deposited coating is uniform over all areas of the work-piece that are in continuous contact with fresh plating solution. The process is applicable to a wide variety of metal and nonmetal substrates. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion and wear resistance as well as heat treating and joining. Filing Code: Ni-332. Producer or source: Occidental Chemical Corporation.


Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1100
Author(s):  
Alexandre M. Emelyanenko ◽  
Valery V. Kaminsky ◽  
Ivan S. Pytskii ◽  
Kirill A. Emelyanenko ◽  
Alexander G. Domantovsky ◽  
...  

The interest in magnesium-based materials is promoted by their biocompatibility, their bioresorbability, and their recently discovered antibacterial potential. Until now, the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced corrosion behavior. To better understand the degradation and usability of magnesium-based alloys, in this study we have fabricated superhydrophobic coatings on a magnesium-based alloy, and analyzed the behavior of this alloy in bacterial dispersions of Pseudomonas aeruginosa and Klebsiella pneumoniae cells in phosphate-buffered saline. It was shown that the immersion of such coatings in bacterial dispersions causes notable changes in the morphology of the samples, dependent on the bacterial dispersion composition and the type of bacterial strain. The interaction of the superhydrophobic coatings with the bacterial dispersion caused the formation of biofilms and sodium polyphosphate films, which provided enhanced barrier properties in magnesium dissolution and hence in dispersion medium alkalization, eventually leading to the inhibition of magnesium substrate degradation. The electrochemical data obtained for superhydrophobic samples in continuous contact with corrosive bacterial dispersions for 48 h indicated a high level of anticorrosion protection.


2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 56-57
Author(s):  
M Painchaud ◽  
S Singh ◽  
R M Penner

Abstract Background Due to the COVID-19 pandemic, clinics were forced to implement telehealth into clinical practice. Inflammatory bowel disease (IBD) patients are a unique population that require long-term care to achieve and maintain deep remission of disease. Thus, they require stable and continuous contact with healthcare providers, often with multiple appointments. We examined an IBD predominant practice, also providing care for general gastrointestinal (GI) conditions in Kelowna, British Columbia. As telehealth has the potential to become a standard of care for clinics, patient satisfaction must be considered. We hypothesize that with the efficacy and ease of remote appointments, there will be an increase in patient satisfaction, quality of care, and quality of communication. Aims We aim to compare the level of patient satisfaction between in-person appointments pre-pandemic, and current remote appointment telehealth practices. Methods An online survey was sent to the 608 patients who had participated in one or more remote appointment between March 15-June 15, 2020. The survey compared the level of patient satisfaction, quality of care, and quality of communication between patient and doctor before and during the pandemic. It was also determined if patients would elect to continue with remote appointments in the future due to ease of use, and time/financial resources saved. Results Of the 273 participants, 80% were IBD patients while 20% were treated for other GI conditions. A total of 78% reported that they would elect to continue with remote appointments as their primary point of care with their doctor. The remaining 22% reported that they prefer in-person visits due to the necessity of a physical exam, yet specified that communication by these remote means was still of good quality. Levels of patient satisfaction before and during the pandemic remained consistent, where 59% of patients assigned a satisfaction rating of 10 (highest) to their pre-pandemic in-person appointments, and 54% of patients assigned a rating of 10 to their remote appointments during the pandemic. Similar consistent results were found for quality of care and quality of communication. A total of 70% of patients reported that if this service had not been available, they would have sought out other forms of care; 18% of the total responses considering emergency care. Conclusions IBD patients at Kelowna Gastroenterology perceived similar levels of satisfaction, quality of care, and quality of communication with both in-person and telehealth appointments. This suggests that telehealth practices may be a cost-effective, sustainable appointment style that provides comparable quality to in-person appointments. Funding Agencies None


Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.


2014 ◽  
Vol 76 (5) ◽  
pp. 580-592 ◽  
Author(s):  
Yong-Joon Kim ◽  
Gershon Elber ◽  
Myung-Soo Kim
Keyword(s):  

1998 ◽  
Vol 2 (3) ◽  
pp. 167-172
Author(s):  
I. V. Feldstein ◽  
N. N. Kuzmin

The paper presents an approach to the simulation of friction interaction. The model does not use any physical descriptions of the processes in the system, but it has simple physical interpretation. It is based on one qualitative experimental result – the value of first Lyapunov exponent drops with normal load. It is shown that the logistic map could be considered as the simplest model of continuous contact. The generalization of the model (which takes into account the discreteness of the real contact) gives results very similar to the experimental ones. It is in the form of a dynamic ensemble with variable structure (DEVS), which has some interesting properties – particularly bifurcation diagrams.


1999 ◽  
Vol 202 (19) ◽  
pp. 2609-2617 ◽  
Author(s):  
J.E. Bertram ◽  
A. Ruina ◽  
C.E. Cannon ◽  
Y.H. Chang ◽  
M.J. Coleman

In brachiation, an animal uses alternating bimanual support to move beneath an overhead support. Past brachiation models have been based on the oscillations of a simple pendulum over half of a full cycle of oscillation. These models have been unsatisfying because the natural behavior of gibbons and siamangs appears to be far less restricted than so predicted. Cursorial mammals use an inverted pendulum-like energy exchange in walking, but switch to a spring-based energy exchange in running as velocity increases. Brachiating apes do not possess the anatomical springs characteristic of the limbs of terrestrial runners and do not appear to be using a spring-based gait. How do these animals move so easily within the branches of the forest canopy? Are there fundamental mechanical factors responsible for the transition from a continuous-contact gait where at least one hand is on a hand hold at a time, to a ricochetal gait where the animal vaults between hand holds? We present a simple model of ricochetal locomotion based on a combination of parabolic free flight and simple circular pendulum motion of a single point mass on a massless arm. In this simple brachiation model, energy losses due to inelastic collisions of the animal with the support are avoided, either because the collisions occur at zero velocity (continuous-contact brachiation) or by a smooth matching of the circular and parabolic trajectories at the point of contact (ricochetal brachiation). This model predicts that brachiation is possible over a large range of speeds, handhold spacings and gait frequencies with (theoretically) no mechanical energy cost. We then add the further assumption that a brachiator minimizes either its total energy or, equivalently, its peak arm tension, or a peak tension-related measure of muscle contraction metabolic cost. However, near the optimum the model is still rather unrestrictive. We present some comparisons with gibbon brachiation showing that the simple dynamic model presented has predictive value. However, natural gibbon motion is even smoother than the smoothest motions predicted by this primitive model.


Author(s):  
Varan Gupta ◽  
Rajesh Kumar ◽  
Shantnav Agarwal ◽  
Indra Narayan Kar ◽  
Jitendra Khatait

Abstract This paper describes skating locomotion in a straight line based on continuous contact of rollers with the surface. Two skates traverse in and out while changing their orientation. Net traction force is generated because of no slip conditions of rollers at the contact. The two skates are in continuous contact with the surface and therefore the balancing problem is circumvented. Different designs are developed and evaluated in order to replicate the desired motion. A heuristic based architecture is developed to move the robot in a straight line.


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