scholarly journals New reference force system of 10MN for build-up force standard machine at jilin institute of metrology

2021 ◽  
Vol 18 ◽  
pp. 100163
Author(s):  
Zhuo Qu ◽  
Hai Lin ◽  
Weijun Huang ◽  
Xiang Ren
Keyword(s):  
Force System

Optimized Attachment to Achieve Different Buccolingual Movement of Maxillary Molars in Clear Aligner Orthodontic System: Biomechanical Analysis

2020 ◽  
Vol 12 (11) ◽  
pp. 1249-1254
Author(s):  
Long Qin ◽  
Qiao Wang ◽  
Dongliang Zhang ◽  
Xin He ◽  
Binbin Wu
Keyword(s):  
Tooth Movement ◽  
Biomechanical Analysis ◽  
Occlusal Surface ◽  
Tooth Surface ◽  
Force System ◽  
Maxillary Molars ◽  
Clear Aligner

The different positions and angles of attachment affecting the buccolingual movement of the maxillary molars, especially lingual tipping and negative torque movements, were biomechanically analyzed in order to determine how to better control and prevent unwanted movement of clear aligners. The aligner can be designed and placed appropriately to improve expected tooth movement. Based on mechanical principles, the force system of attachment was analyzed, and the optimum attachment position and angle for tipping and negative torque movement was determined. Attachment close to the enamel-cementum junction (ECJ) was found to achieve the best F (M/L) during negative torque movement; however, the angle should also be adjusted. Attachment close to the occlusal surface achieved greater tipping force at specific angles. When more tipping movement is required, it is recommended to place the attachment 3–5 mm from the ECJ. The angle of the attachment should be 110–120 degrees from the tooth surface. When place the attachment 4–5 mm from the ECJ, the angle of the attachment should be between 145 and 146.5 degrees.

scholarly journals Molar Uprighting: A Considerable and Safe Decision to Avoid Prosthetic Treatment

2017 ◽  
Vol 11 (1) ◽  
pp. 466-475 ◽  
Author(s):  
Taísa Boamorte Raveli ◽  
Dirceu Barnabé Raveli ◽  
Kelei Cristina de Mathias Almeida ◽  
Ary dos Santos Pinto
Keyword(s):  
Orthodontic Treatment ◽  
Tooth Movement ◽  
Orthodontic Tooth Movement ◽  
Female Adult ◽  
Bone Apposition ◽  
Force System ◽  
Second Molar ◽  
Space Closure ◽  
Practical Implications ◽  
Lower Molar

Background: Tipped lower molar over edentulous space is very common in orthodontics practice when adults seek treatment. The segmented arch technique features a predictable force system that provides a controlled release of force that can produce light and continuous tooth movement. Case Description: A female adult patient, who lost a permanent lower first molar, needed correction of the position of her permanent first molar place. Instead of making space for rehabilitation, it was closed after second molar uprighting and a balanced interdigitation was created without prosthetics. The patient was successfully treated with segmented arch technique using root correction spring activated with geometry VI to promote uprighting of a tipped molar and Niti spring coil to promote space closure. Practical Implications: Segmented arch technique is known to provide predictable light and continuous forces, which is very much indicated in adult treatment. There are several things to consider when orthodontically treating adult patients. Their periodontal conditions might not be ideal, less bone apposition may occur, and side effects of orthodontic tooth movement are expected. Thus, a predictable and controlled orthodontic treatment is needed.

scholarly journals Projection Welding of Nuts with Full Projections with Use of Electromechanical Operating Force System

2019 ◽  
Vol 2019 (2) ◽  
pp. 7-16
Author(s):  
Zygmunt Mikno ◽  
Szymon Kowieski ◽  
Adam Pilarczyk
Keyword(s):  
Force System ◽  
Projection Welding

scholarly journals Looking for Options to Sustainably Fixate Nitrogen. Are Molecular Metal Oxides Catalysts a Viable Avenue?

2021 ◽  
Vol 9 ◽  
Author(s):  
Rebeca González-Cabaleiro ◽  
Jake A. Thompson ◽  
Laia Vilà-Nadal
Keyword(s):  
Metal Oxides ◽  
Carbon Dioxide Emissions ◽  
Triple Bond ◽  
Industrial Process ◽  
Modern Society ◽  
Small Scale ◽  
Scale Production ◽  
Ammonia Production ◽  
Force System ◽  
Bosch Process

Fast and reliable industrial production of ammonia (NH3) is fundamentally sustaining modern society. Since the early 20th Century, NH3 has been synthesized via the Haber–Bosch process, running at conditions of around 350–500°C and 100–200 times atmospheric pressure (15–20 MPa). Industrial ammonia production is currently the most energy-demanding chemical process worldwide and contributes up to 3% to the global carbon dioxide emissions. Therefore, the development of more energy-efficient pathways for ammonia production is an attractive proposition. Over the past 20 years, scientists have imagined the possibility of developing a milder synthesis of ammonia by mimicking the nitrogenase enzyme, which fixes nitrogen from the air at ambient temperatures and pressures to feed leguminous plants. To do this, we propose the use of highly reconfigurable molecular metal oxides or polyoxometalates (POMs). Our proposal is an informed design of the polyoxometalate after exploring the catabolic pathways that cyanobacteria use to fix N2 in nature, which are a different route than the one followed by the Haber–Bosch process. Meanwhile, the industrial process is a “brute force” system towards breaking the triple bond N-N, needing high pressure and high temperature to increase the rate of reaction, nature first links the protons to the N2 to later easier breaking of the triple bond at environmental temperature and pressure. Computational chemistry data on the stability of different polyoxometalates will guide us to decide the best design for a catalyst. Testing different functionalized molecular metal oxides as ammonia catalysts laboratory conditions will allow for a sustainable reactor design of small-scale production.

scholarly journals An Analysis of the Stress Induced in the Periodontal Ligament during Extrusion and Rotation Movements: A Finite Element Method Linear Study Part I

2015 ◽  
Vol 16 (9) ◽  
pp. 740-743 ◽  
Author(s):  
HP Raghuveer ◽  
M Hemanth ◽  
MS Rani ◽  
Chathura Hegde ◽  
B Vedavathi ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Compressive Stress ◽  
Periodontal Ligament ◽  
Tooth Movement ◽  
Root Resorption ◽  
Orthodontic Tooth Movement ◽  
3D Fem ◽  
Force System ◽  
Element Method

ABSTRACT Background Orthodontic tooth movement occurs due to various biomechanical changes in the periodontium. Forces within the optimal range yield maximum tooth movement with minimum deleterious effects. Among various types of tooth movements, extrusion and rotational movements are seen to be associated with the least amount of root resorption and have not been studied in detail. Therefore in this study, the stress patterns in the periodontal ligament (PDL) were evaluated with extrusion and rotational movements using the finite element method FEM. Materials and methods A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modeling software. Stresses in the PDL were evaluated with extrusive and rotational movements by a 3D FEM using ANSYS software with linear material properties. Results It was observed that with the application of extrusive load, the tensile stresses were seen at the apex, whereas the compressive stress was distributed at the cervical margin. With the application of rotational movements, maximum compressive stress was distributed at the apex and cervical third, whereas the tensile stress was distributed on cervical third of the PDL on the lingual surface. Conclusion For extrusive movements, stress values over the periodontal ligament was within the range of optimal stress value as proposed by Lee, with a given force system by Profitt as optimum forces for orthodontic tooth movement using linear properties. During rotation there are stresses concentrated at the apex, hence due to the concentration of the compressive forces at the apex a clinician must avoid placing heavy stresses during tooth movement. How to cite this article Hemanth M, Raghuveer HP, Rani MS, Hegde C, Kabbur KJ, Vedavathi B, Chaithra D. An Analysis of the Stress Induced in the Periodontal Ligament during Extrusion and Rotation Movements: A Finite Element Method Linear Study Part I. J Contemp Dent Pract 2015;16(9):740-743.

The large-scale structure of homogeneous turbulence

1967 ◽  
Vol 27 (3) ◽  
pp. 581-593 ◽  
Author(s):  
P. G. Saffman
Keyword(s):  
Large Scale ◽  
Isotropic Turbulence ◽  
Homogeneous Turbulence ◽  
Wave Number ◽  
Initial Instant ◽  
Force System ◽  
Correlation Tensor ◽  
Number Magnitude ◽  
Small Wave Number ◽  
Conservation Of Momentum

A field of homogeneous turbulence generated at an initial instant by a distribution of random impulsive forces is considered. The statistical properties of the forces are assumed to be such that the integral moments of the cumulants of the force system all exist. The motion generated has the property that at the initial instant\[ E(\kappa) = C\kappa^2 + o(\kappa^2), \]whereE(k) is the energy spectrum function,kis the wave-number magnitude, andCis a positive number which is not in general zero. The corresponding forms of the velocity covariance spectral tensor and correlation tensor are determined. It is found that the terms in the velocity covarianceRij(r) areO(r−3) for large values of the separation magnituder.An argument based on the conservation of momentum is used to show thatCis a dynamical invariant and that the forms of the velocity covariance at large separation and the spectral tensor at small wave number are likewise invariant. For isotropic turbulence, the Loitsianski integral diverges but the integral\[ \int_0^{\infty} r^2R(r)dr = \frac{1}{2}\pi C \]exists and is invariant.

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