scholarly journals Functionalization of Screw Implants with Superelastic Structured Nitinol Anchoring Elements

2021 ◽  
Author(s):  
Isabell Hamann ◽  
Stefan Schleifenbaum ◽  
Christian Rotsch ◽  
Welf-Guntram Drossel ◽  
Christoph-Eckhard Heyde ◽  
...  
Keyword(s):  
Demographic Change ◽  
Negative Impact ◽  
Operating Conditions ◽  
Artificial Bone ◽  
Biomechanical Test ◽  
Pull Out ◽  
Functional Patterns ◽  
Surgical Conditions ◽  
Set Up ◽  
Ct Studies

Abstract Demographic change is leading to a increase in the number of osteoporotic patients, so that a rethink is required in implantology in order to be able to guarantee adequate anchoring stability in the bone. The functional modification of conventional standard screw implants by the use of superelastic, structured Ti6Al4V anchoring elements promises great potential for increasing anchoring stability. For this purpose, conventional screw implants were mechanically machined and extended so that structured-superelastic-positionable-Ti6Al4V anchoring elements could be used. The set-up of the anchoring elements was investigated in CT studies in an artificial bone. In a subsequent handling test, the handling of the function samples was evaluated under surgical conditions. The anchorage stability to standard screw implants was investigated in a final pull-out test according to "ASTM F543".The functionalization of conventional screw implants with structured superelastic Ti6Al4V anchoring elements is technically realizable. It has been demonstrated that the anchoring elements can be set up in the artificial bone without any problems. The anchorage mechanism is easy to handle under operating conditions and the anchoring elements have no negative impact on the surgical procedure. It was shown that, compared to conventional standard screws, more mechanical work is required to remove the functional patterns completely from the bone.In summary, it was shown that conventional standard screw implants can be functionalized with Ti6Al4V structured NiTi anchoring elements and are suitable for orthopedic and neurosurgical use. A first biomechanical test showed that the anchoring stability can be increased by the anchoring elements.

scholarly journals Functionalization of screw implants with superelastic structured Nitinol anchoring elements

2022 ◽  
Vol 21 (1) ◽  
Author(s):  
Isabell Hamann ◽  
Stefan Schleifenbaum ◽  
Christian Rotsch ◽  
Welf-Guntram Drossel ◽  
Christoph-Eckhard Heyde ◽  
...  
Keyword(s):  
Negative Influence ◽  
Test Methods ◽  
Operating Conditions ◽  
The Novel ◽  
Artificial Bone ◽  
Functional Patterns ◽  
New Type ◽  
Current Point ◽  
Surgical Conditions ◽  
Set Up

Abstract Background Demographic change is leading to an increase in the number of osteoporotic patients, so a rethink is required in implantology in order to be able to guarantee adequate anchoring stability in the bone. The functional modification of conventional standard screw implants using superelastic, structured Ti6Al4V anchoring elements promises great potential for increasing anchoring stability. Methods For this purpose, conventional screw implants were mechanically machined and extended so that structured-superelastic-positionable-Ti6Al4V anchoring elements could be used. The novel implants were investigated with three tests. The setup of the anchoring elements was investigated in CT studies in an artificial bone. In a subsequent simplified handling test, the handling of the functional samples was evaluated under surgical conditions. The anchorage stability compared to standard screw implants was investigated in a final pullout test according to ASTM F543—the international for the standard specification and test methods for metallic medical bone screws. Results The functionalization of conventional screw implants with structured superelastic Ti6Al4V anchoring elements is technically realizable. It was demonstrated that the anchoring elements can be set up in the artificial bone without any problems. The anchorage mechanism is easy to handle under operating conditions. The first simplified handling test showed that at the current point of the investigations, the anchoring elements have no negative influence on the surgical procedure (especially under the focus of screw implantation). Compared to conventional standard screws, more mechanical work is required to remove the functional patterns completely from the bone. Conclusion In summary, it was shown that conventional standard screw implants can be functionalized with Ti6Al4V-structured NiTi anchoring elements and the new type of screws are suitable for orthopedic and neurosurgical use. A first biomechanical test showed that the anchoring stability could be increased by the anchoring elements.

Work Stress and Organisational Citizenship Behaviours (OCBs) in Call Centers Employees

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Sunita ◽  
Urvashi Singh ◽  
Shalini Singh ◽  
Rajnee Sharma
Keyword(s):  
Negative Impact ◽  
Call Centers ◽  
Negative Relationship ◽  
Married Couples ◽  
Call Centre ◽  
Simple Correlation ◽  
Nuclear Families ◽  
Set Up ◽  
Stress At Work ◽  
The Relationship

The present study was conducted to examine the relationship between organisational stress and organisational citizenship behaviours (OCBs) in employees of call centers. The study also further explored as how stress at work set-up has negative impact on OCBs. A sample of 250 employees working in call centre of Gurgaon belonging to an age group of 25-30 years were selected on availability basis. All were working married couples living in nuclear families. Job stress survey (Spielberger & Vagg, 1999) and Organisational Citizenship Behaviour (Bateman & Organ, 1983) were administered. Data was analysed by using simple correlation and multiple regression. Results showed the negative relationship between organisational stress and OCBs. Results of regression analysis also exhibited the negative impact of stress on OCBs. The implications for the employees are discussed.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

scholarly journals A 2-D model for Intermediate Temperature Solid Oxide Fuel Cells Preliminarily Validated on Local Values

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 36 ◽  
Author(s):  
Bruno Conti ◽  
Barbara Bosio ◽  
Stephen John McPhail ◽  
Francesca Santoni ◽  
Davide Pumiglia ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Intermediate Temperature ◽  
Physical Parameters ◽  
Local Concentration ◽  
Oxide Fuel ◽  
Molten Carbonate ◽  
Experimental Apparatus ◽  
Set Up

Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) technology offers interesting opportunities in the panorama of a larger penetration of renewable and distributed power generation, namely high electrical efficiency at manageable scales for both remote and industrial applications. In order to optimize the performance and the operating conditions of such a pre-commercial technology, an effective synergy between experimentation and simulation is fundamental. For this purpose, starting from the SIMFC (SIMulation of Fuel Cells) code set-up and successfully validated for Molten Carbonate Fuel Cells, a new version of the code has been developed for IT-SOFCs. The new release of the code allows the calculation of the maps of the main electrical, chemical, and physical parameters on the cell plane of planar IT-SOFCs fed in co-flow. A semi-empirical kinetic formulation has been set-up, identifying the related parameters thanks to a devoted series of experiments, and integrated in SIMFC. Thanks to a multi-sampling innovative experimental apparatus the simultaneous measurement of temperature and gas composition on the cell plane was possible, so that a preliminary validation of the model on local values was carried out. A good agreement between experimental and simulated data was achieved in terms of cell voltages and local temperatures, but also, for the first time, in terms of local concentration on the cell plane, encouraging further developments. This numerical tool is proposed for a better interpretation of the phenomena occurring in IT-SOFCs and a consequential optimization of their performance.

Artificial Neural Networks Used As a Rule Selector for Fuzzy Logic Controllers

1993 ◽  
Author(s):  
Shou-Heng Huang ◽  
Ron M. Nelson
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Absolute Error ◽  
Operating Conditions ◽  
Delta Rule ◽  
Rule Sets ◽  
Artificial Neural ◽  
Artificial Neural Network Ann ◽  
Set Up ◽  
And Control

Abstract A feedforward, three-layer, partially-connected artificial neural network (ANN) is proposed to be used as a rule selector for a rule-based fuzzy logic controller. This will allow the controller to adapt to various control modes and operating conditions for different plants. A principal advantage of an ANN over a look up table is that the ANN can make good estimates to fill in for missing data. The control modes, operating conditions, and control rule sets are encoded into binary numbers as the inputs and outputs for the ANN. The General Delta Rule is used in the backpropagation learning process to update the ANN weights. The proposed ANN has a simple topological structure and results in a simple analysis and relatively easy implementation. The average square error and the maximal absolute error are used to judge if the correct connections between neurons are set up. Computer simulations are used to demonstrate the effectiveness of this ANN as a rule selector.

Solar Gasification of Biomass: A Molten Salt Pyrolysis Study

2004 ◽  
Vol 126 (3) ◽  
pp. 850-857 ◽  
Author(s):  
Roman Adinberg ◽  
Michael Epstein ◽  
Jacob Karni
Keyword(s):  
Solar Energy ◽  
Molten Salt ◽  
Operating Conditions ◽  
Thermochemical Conversion ◽  
Salt Medium ◽  
Feasible Option ◽  
Temperature Liquid ◽  
Set Up ◽  
Biomass Particles ◽  
Pyrolysis Of Biomass

A novel solar process and reactor for thermochemical conversion of biomass to synthesis gas is described. The concept is based on dispersion of biomass particles in a molten inorganic salt medium and, simultaneously, absorbing, storing and transferring solar energy needed to perform pyrolysis reactions in the high-temperature liquid phase. A lab-scale reactor filled with carbonates of potassium and sodium was set up to study the kinetics of fast pyrolysis and the characteristics of transient heat transfer for cellulose particles (few millimeters size) introduced into the molten salt medium. The operating conditions were reaction temperatures of 1073–1188 K and a particle peak-heating rate of 100 K/sec. The assessments performed for a commercial-scale solar reactor demonstrate that pyrolysis of biomass particles dispersed in a molten salt phase could be a feasible option for the continuous, round-the-clock production of syngas, using solar energy only.

Modeling and prediction for the oxidation efficiency of magnesium sulfite in aeration tank of magnesium-based seawater exhaust gas clean system

2017 ◽  
Vol 233 (1) ◽  
pp. 164-173
Author(s):  
Quan Liu ◽  
Yimin Zhu ◽  
Tie Li ◽  
Xiaojia Tang ◽  
Weifeng Liu ◽  
...  
Keyword(s):  
Flow Field ◽  
Initial Conditions ◽  
Negative Impact ◽  
Fluid Model ◽  
Aeration Tank ◽  
Exhaust Gas ◽  
Clean System ◽  
Physics Modeling ◽  
Set Up ◽  
Oxidation Efficiency

In magnesium-based seawater exhaust gas clean system, the desulfurization by-product, magnesium sulfite (MgSO3), has a negative impact on the ecological environment, which needs to be treated to make harmless. Due to the limited space on board, the aeration oxidation method is used to convert it to magnesium sulfate. Because of the variable size, shape and flow field of aeration tank, it is difficult and expensive to design and verify the oxidation efficiency of the aeration tank by experimental method. In this work, in order to predict the oxidation efficiency accurately, RFlow, a computational fluid dynamics software, was used to analyze the flow field and MgSO3 oxidation reaction in aeration tank. The subdomain technology was adopted for physics modeling and mesh generation of the aeration tank, and the total number of meshes was 285,000. The multi-phase flow field model was set up using the multi-fluid model and dispersive k-ε turbulence model. Under the given initial conditions, the predicted oxidation efficiency was 94.2%. Compared with the results of the actual ship test, the prediction model for MgSO3 oxidation efficiency of the aeration tank is reliable.

scholarly journals A Study on the Entanglement and High-Strength Mechanism of Spunlaced Nonwoven Fabric of Hydrophilic PET Fibers

2013 ◽  
Vol 8 (4) ◽  
pp. 155892501300800 ◽  
Author(s):  
Hong Wang ◽  
Jingjing Zhu ◽  
Xiangyu Jin ◽  
Haibo Wu
Keyword(s):  
Tensile Strength ◽  
High Strength ◽  
Nonwoven Fabric ◽  
Fiber Content ◽  
Nonwoven Fabrics ◽  
Pull Out ◽  
Fundamental Research ◽  
Pet Fibers ◽  
Set Up

Spunlaced nonwoven fabrics have been widely used recently, but fundamental research on the spunlaced nonwoven process is relatively weak. It is inexplicit until now how fibers are entangled with each other during the hydroentangling process. In this paper, a pull-out experiment designed to study the entanglement properties of spunlaced nonwoven fabrics using common and hydrophilic PET fibers as objects is described. It was found that the broken fiber content can be used to represent the entanglement intensity of the spunlaced nonwoven fabrics. In addition, a formula was set up to calculate the tensile strength of the spunlaced nonwoven fabric based on its pull-out behavior.

scholarly journals Changes And New Constraints In The Competition Rules Enforcement Due To Accession: The Perception Of The Romanian Companies

2011 ◽  
Vol 7 (4) ◽  
Author(s):  
Alina Mihaela Dima
Keyword(s):  
Competition Policy ◽  
Negative Impact ◽  
Free Market ◽  
National Level ◽  
Well Being ◽  
Business Environment ◽  
Competition Rules ◽  
Set Up ◽  
The One ◽  
The Right

Many times, in the attempt to win or to maintain an advantageous position on the market, the economic agent will use a whole arsenal of practices (inclusively and mostly from the marketing field), most of them anticompetitive, with a negative impact on the business environment, which also affects the well-being of the consumer. The policy in the field of competition is the one that defines these types of behaviour and penalizes them depending on the importance of their negative impact, by creating a complex and coherent legislative and institutional mechanism. The right enforcement of the competition policy at the national level is the key in this process, but this should be coordinated with the regional and international objectives and regulations in this field. Romania is facing a double challenge: on the one side, it had to set up a competition policy, which was almost ignored before the90s, on the other side, it had to comply, recently, with high standards in the field, as an EU candidate. Now, as a member state, the promotion of a competition culture becomes a must, along with the design of an adequate system of information and knowledge dissemination for all of those involved. The paper is based on a original and qualitative research and aims at emphasising the increased necessity of the promotion of a competition culture for the competitiveness of the Romanian business environment on the European level in the new context of accession. This will help Romanian business to face the competition challenges within a more extended single European market, as an essential issue of the free market economy status recently granted, and accordingly to the most important EU objectives set up at Lisabon to become the most competitive economy in the world up to 2010.

scholarly journals Kryzys filozofii polityki

2011 ◽  
Vol 13 ◽  
pp. 23-42
Author(s):  
Barbara Markowska
Keyword(s):  
20Th Century ◽  
Subject Matter ◽  
Theoretical Consideration ◽  
Scientific Discipline ◽  
Operating Conditions ◽  
Decisive Factor ◽  
Early 20Th Century ◽  
Leo Strauss ◽  
Set Up ◽  
Scholarly Pursuit

The purport of the article is a reflection on the operating conditions of the philosophy of politics, beginning with its crisis, as described by Leo Strauss in the early 20th century and continuing up to the latest proposals, which emerged at the turn of the 20th and 21st centuries. First, the author poses a question regarding the essence of this crisis; was it related to the scientific paradigm of the philosophy of politics applied hitherto or, rather, to the very subject matter of this scholarly pursuit, which is to say, to politics itself. A scientific discipline must be able to delineate its subject matter and if the latter undergoes an unexpected modification, the former suffers a crisis. Was this what happened to politics itself? What was the decisive factor which caused it to escape a theoretical consideration that ceased to be a systematic reflection, in short, ceased to be science, only to become philosophy again, whereby the author understands ‘philosophy’ as a level of reflection such as to allow itself to posit subliminal questions purely in order to set up the determinants for further thinking as to what science is, what politics is and what makes politics different from non-politics.

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