scholarly journals Flexure Pivot Oscillator With Intrinsically Tuned Isochronism

2019 ◽  
Vol 142 (7) ◽  
Author(s):  
E. Thalmann ◽  
M. H. Kahrobaiyan ◽  
I. Vardi ◽  
S. Henein
Keyword(s):  
Oscillation Amplitude ◽  
Analytical Models ◽  
Essential Property ◽  
Proof Of Concept ◽  
Parasitic Motion ◽  
Element Simulation ◽  
Spiral Spring ◽  
Elastic Nonlinearity ◽  
The One ◽  
Nonlinear Elastic

Abstract The most important property for accurate mechanical time bases is isochronism: the independence of period from oscillation amplitude. This paper develops a new concept in isochronism adjustment for flexure-based watch oscillators. Flexure pivot oscillators, which would advantageously replace the traditional balance wheel-spiral spring oscillator used in mechanical watches due to their significantly lower friction, exhibit nonlinear elastic properties that introduce an isochronism defect. Rather than minimizing this defect, we are interested in controlling it to compensate for external defects such as the one introduced by escapements. We show that this can be done by deriving a formula that expresses the change of frequency of the oscillator with amplitude, i.e., isochronism defect, caused by elastic nonlinearity. To adjust the isochronism, we present a new method that takes advantage of the second-order parasitic motion of flexures and embody it in a new architecture we call the co-RCC flexure pivot oscillator. In this realization, the isochronism defect of the oscillator is controlled by adjusting the stiffness of parallel flexures before fabrication through their length Lp, which has no effect on any other crucial property, including nominal frequency. We show that this method is also compatible with post-fabrication tuning by laser ablation. The advantage of our design is that isochronism tuning is an intrinsic part of the oscillator, whereas previous isochronism correctors were mechanisms added to the oscillator. The results of our previous research are also implemented in this mechanism to achieve gravity insensitivity, which is an essential property for mechanical watch time bases. We derive analytical models for the isochronism and gravity sensitivity of the oscillator and validate them by finite element simulation. We give an example of dimensioning this oscillator to reach typical practical watch specifications and show that we can tune the isochronism defect with a resolution of 1 s/day within an operating range of 10% of amplitude. We present a mock-up of the oscillator serving as a preliminary proof-of-concept.

scholarly journals Design of a Flexure Rotational Time Base with Varying Inertia

2021 ◽  
pp. 1-23
Author(s):  
Etienne Thalmann ◽  
Simon Henein
Keyword(s):  
Practical Method ◽  
Analytical Models ◽  
Elastic Behavior ◽  
Time Base ◽  
Proof Of Concept ◽  
Inertia Effects ◽  
Quartz Oscillator ◽  
Mems Oscillators ◽  
Nonlinear Elastic ◽  
Frequency Variations

Abstract Flexure oscillators are promising time bases thanks to their high quality factor and monolithic design compatible with microfabrication. In mechanical watchmaking, they could advantageously replace the traditional balance and hairspring oscillator, leading to improvements in timekeeping accuracy, autonomy and assembly. As MEMS oscillators, their performance can rival that of the well-established quartz oscillator. However, their inherent nonlinear elastic behavior can introduce a variation of their frequency with amplitude called isochronism defect, a major obstacle to accurate timekeeping in mechanical watches. Previous research has focused on addressing this issue by controlling the elastic properties of flexure oscillators. Yet, these oscillators exhibit other amplitude-related frequency variations caused by changes of inertia with amplitude. In this article, we not only improve existing models by taking into account inertia effects but also present a new way of using them to adjust the isochronism defect. This results in a better understanding of flexure oscillators and an alternative way of tuning isochronism by acting on inertia instead of stiffness. This also opens the door to new promising architectures such as the new Rotation-Dilation Coupled Oscillator (RDCO) whose symmetry has the advantage of minimizing the influence of linear accelerations on its frequency (the other major limitation of flexure oscillators). We derive analytical models for the isochronism of this oscillator, show a dimensioning with compensating inertia and stiffness variations and present a practical method for post-fabrication isochronism tuning. The models are validated by FEM and mock-ups serve as preliminary proof-of-concept.

scholarly journals Analytical Model of Induction Machines with Multiple Cage Faults Using the Winding Tensor Approach

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5076
Author(s):  
Javier Martinez-Roman ◽  
Ruben Puche-Panadero ◽  
Angel Sapena-Bano ◽  
Carla Terron-Santiago ◽  
Jordi Burriel-Valencia ◽  
...  
Keyword(s):  
Computational Cost ◽  
Induction Machines ◽  
Diagnostic Techniques ◽  
Analytical Models ◽  
Tensor Algebra ◽  
Diagnostic Systems ◽  
Technical Literature ◽  
Twin Model ◽  
Ring Segment ◽  
The One

Induction machines (IMs) are one of the main sources of mechanical power in many industrial processes, especially squirrel cage IMs (SCIMs), due to their robustness and reliability. Their sudden stoppage due to undetected faults may cause costly production breakdowns. One of the most frequent types of faults are cage faults (bar and end ring segment breakages), especially in motors that directly drive high-inertia loads (such as fans), in motors with frequent starts and stops, and in case of poorly manufactured cage windings. A continuous monitoring of IMs is needed to reduce this risk, integrated in plant-wide condition based maintenance (CBM) systems. Diverse diagnostic techniques have been proposed in the technical literature, either data-based, detecting fault-characteristic perturbations in the data collected from the IM, and model-based, observing the differences between the data collected from the actual IM and from its digital twin model. In both cases, fast and accurate IM models are needed to develop and optimize the fault diagnosis techniques. On the one hand, the finite elements approach can provide highly accurate models, but its computational cost and processing requirements are very high to be used in on-line fault diagnostic systems. On the other hand, analytical models can be much faster, but they can be very complex in case of highly asymmetrical machines, such as IMs with multiple cage faults. In this work, a new method is proposed for the analytical modelling of IMs with asymmetrical cage windings using a tensor based approach, which greatly reduces this complexity by applying routine tensor algebra to obtain the parameters of the faulty IM model from the healthy one. This winding tensor approach is explained theoretically and validated with the diagnosis of a commercial IM with multiple cage faults.

Modeling Method of Constitutive Law of Rubber Hyperelasticity Based on Finite Element Simulations

2003 ◽  
Vol 76 (1) ◽  
pp. 271-285 ◽  
Author(s):  
Li-Rong Wang ◽  
Zhen-Hua Lu
Keyword(s):  
Finite Element ◽  
Finite Element Simulations ◽  
Constitutive Law ◽  
Modeling Technique ◽  
Characteristic Analysis ◽  
Rubber Material ◽  
Element Simulation ◽  
Tension And Compression ◽  
Nonlinear Elastic ◽  
Elastic Characteristics

Abstract This paper is to present a method and procedure for modeling the constitutive law of anti-vibration rubber hyperelasticity based on finite element simulations. The hyperelasticity of rubber-like material is briefly summarized first. Then a method and procedure for determining an accurate constitutive law of rubber hyperelasticity from uniaxial tension and compression experiment data is presented and implemented. Due to nonlinear elastic properties of rubber and application limitations of various forms of constitutive law, results of finite element simulation to rubber material experiments show that different forms of constitutive law have to be adopted in different ranges of strain. The proposed procedure to obtain an appropriate constitutive law of rubber hyperelasticity of vibration isolator provides engineers with an effective modeling technique for design and analysis of anti-vibration rubber components. Finally, models of three kinds of rubber materials of a hydraulically damped rubber mount (HDM) are determined by tests and finite element simulations and applied to static and dynamic characteristic analysis of the HDM. The predicted elastic characteristics of the HDM and its major rubber components agree well with experimental data, which demonstrates the practicability and effectiveness of the presented modeling technique to modeling engineering rubber materials in dynamic systems.

scholarly journals Proof of Concept for an Ultrasensitive Technique to Detect and Localize Sources of Elastic Nonlinearity Using Phononic Crystals

2017 ◽  
Vol 118 (21) ◽  
Author(s):  
M. Miniaci ◽  
A. S. Gliozzi ◽  
B. Morvan ◽  
A. Krushynska ◽  
F. Bosia ◽  
...  
Keyword(s):  
Phononic Crystals ◽  
Proof Of Concept ◽  
Elastic Nonlinearity

scholarly journals Understanding Screaming Channels: From a Detailed Analysis to Improved Attacks

2020 ◽  
pp. 358-401
Author(s):  
Giovanni Camurati ◽  
Aurélien Francillon ◽  
François-Xavier Standaert
Keyword(s):  
Spatial Diversity ◽  
Low Noise ◽  
Security Evaluation ◽  
The Novel ◽  
Proof Of Concept ◽  
Wireless Devices ◽  
Side Channels ◽  
Security Evaluations ◽  
The One

Recently, some wireless devices have been found vulnerable to a novel class of side-channel attacks, called Screaming Channels. These leaks might appear if the sensitive leaks from the processor are unintentionally broadcast by a radio transmitter placed on the same chip. Previous work focuses on identifying the root causes, and on mounting an attack at a distance considerably larger than the one achievable with conventional electromagnetic side channels, which was demonstrated in the low-noise environment of an anechoic chamber. However, a detailed understanding of the leak, attacks that take full advantage of the novel vector, and security evaluations in more practical scenarios are still missing. In this paper, we conduct a thorough experimental analysis of the peculiar properties of Screaming Channels. For example, we learn about the coexistence of intended and unintended data, the role of distance and other parameters on the strength of the leak, the distortion of the leakmodel, and the portability of the profiles. With such insights, we build better attacks. We profile a device connected via cable with 10000·500 traces. Then, 5 months later, we attack a different instance at 15m in an office environment. We recover the AES-128 key with 5000·1000 traces and key enumeration up to 223. Leveraging spatial diversity, we mount some attacks in the presence of obstacles. As a first example of application to a real system, we show a proof-of-concept attack against the authentication method of Google Eddystone beacons. On the one side, this work lowers the bar for more realistic attacks, highlighting the importance of the novel attack vector. On the other side, it provides a broader security evaluation of the leaks, helping the defender and radio designers to evaluate risk, and the need of countermeasures.

scholarly journals Geomatics and Soft Computing Techniques for Infrastructural Monitoring

2020 ◽  
Vol 12 (4) ◽  
pp. 1606 ◽  
Author(s):  
Vincenzo Barrile ◽  
Antonino Fotia ◽  
Giovanni Leonardi ◽  
Raffaele Pucinotti
Keyword(s):  
Soft Computing ◽  
Structural Model ◽  
Control Unit ◽  
Machine Learning Techniques ◽  
Analytical Models ◽  
Risk Level ◽  
Behavior Monitoring ◽  
Learning Techniques ◽  
Soft Computing Techniques ◽  
The One

Structural Health Monitoring (SHM) allows us to have information about the structure under investigation and thus to create analytical models for the assessment of its state or structural behavior. Exceeded a predetermined danger threshold, the possibility of an early warning would allow us, on the one hand, to suspend risky activities and, on the other, to reduce maintenance costs. The system proposed in this paper represents an integration of multiple traditional systems that integrate data of a different nature (used in the preventive phase to define the various behavior scenarios on the structural model), and then reworking them through machine learning techniques, in order to obtain values to compare with limit thresholds. The risk level depends on several variables, specifically, the paper wants to evaluate the possibility of predicting the structure behavior monitoring only displacement data, transmitted through an experimental transmission control unit. In order to monitor and to make our cities more “sustainable”, the paper describes some tests on road infrastructure, in this contest through the combination of geomatics techniques and soft computing.

scholarly journals Neurophenomenology of near-death experience memory in hypnotic recall: a within-subject EEG study

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Charlotte Martial ◽  
Armand Mensen ◽  
Vanessa Charland-Verville ◽  
Audrey Vanhaudenhuyse ◽  
Daniel Rentmeister ◽  
...  
Keyword(s):  
Subjective Experience ◽  
Brain Activity ◽  
Alpha Activity ◽  
High Density ◽  
Proof Of Concept ◽  
Time Period ◽  
Death Experience ◽  
Eeg Changes ◽  
The One ◽  
Near Death Experiences

Abstract The neurobiological basis of near-death experiences (NDEs) is unknown, but a few studies attempted to investigate it by reproducing in laboratory settings phenomenological experiences that seem to closely resemble NDEs. So far, no study has induced NDE-like features via hypnotic modulation while simultaneously measuring changes in brain activity using high-density EEG. Five volunteers who previously had experienced a pleasant NDE were invited to re-experience the NDE memory and another pleasant autobiographical memory (dating to the same time period), in normal consciousness and with hypnosis. We compared the hypnosis-induced subjective experience with the one of the genuine experience memory. Continuous high-density EEG was recorded throughout. At a phenomenological level, we succeeded in recreating NDE-like features without any adverse effects. Absorption and dissociation levels were reported as higher during all hypnosis conditions as compared to normal consciousness conditions, suggesting that our hypnosis-based protocol increased the felt subjective experience in the recall of both memories. The recall of a NDE phenomenology was related to an increase of alpha activity in frontal and posterior regions. This study provides a proof-of-concept methodology for studying the phenomenon, enabling to prospectively explore the NDE-like features and associated EEG changes in controlled settings.

scholarly journals Extending Fibre Nonlinear Interference Power Modelling to Account for General Dual-Polarisation 4D Modulation Formats

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1324
Author(s):  
Gabriele Liga ◽  
Astrid Barreiro ◽  
Hami Rabbani ◽  
Alex Alvarado
Keyword(s):  
Optical Communication ◽  
Average Power ◽  
Noise Model ◽  
Analytical Models ◽  
Modulation Formats ◽  
First Order ◽  
Modulation Format ◽  
The One ◽  
Mathematical Derivation ◽  
Mutually Independent

In optical communications, four-dimensional (4D) modulation formats encode information onto the quadrature components of two arbitrary orthogonal states of polarisation of the optical field. Many analytical models available in the optical communication literature allow, within a first-order perturbation framework, the computation of the average power of the nonlinear interference (NLI) accumulated in coherent fibre-optic transmission systems. However, all such models only operate under the assumption of transmitted polarisation-multiplexed two-dimensional (PM-2D) modulation formats, which only represent a limited subset of the possible dual-polarisation 4D (DP-4D) formats. Namely, only those where data transmitted on each polarisation channel are mutually independent and identically distributed. This paper presents a step-by-step mathematical derivation of the extension of existing NLI models to the class of arbitrary DP-4D modulation formats. In particular, the methodology adopted follows the one of the popular enhanced Gaussian noise model, albeit dropping most assumptions on the geometry and statistic of the transmitted 4D modulation format. The resulting expressions show that, whilst in the PM-2D case the NLI power depends only on different statistical high-order moments of each polarisation component, for a general DP-4D constellation, several other cross-polarisation correlations also need to be taken into account.

Effectiveness of the One-Minute Preceptor Model for Diagnosing the Patient and the Learner: Proof of Concept

2004 ◽  
Vol 79 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Eva Aagaard ◽  
Arianne Teherani ◽  
David M. Irby
Keyword(s):  
Proof Of Concept ◽  
The One

Experimental investigation on the secondary instability of liquid-fluidized beds and the formation of bubbles

2002 ◽  
Vol 470 ◽  
pp. 359-382 ◽  
Author(s):  
PAUL DURU ◽  
ÉLISABETH GUAZZELLI
Keyword(s):  
Fluidized Beds ◽  
Secondary Instability ◽  
Analytical Models ◽  
Physical Origin ◽  
Weakly Nonlinear ◽  
One Dimensional ◽  
Numerical Studies ◽  
Wavy Structure ◽  
Nonlinear Simulations ◽  
The One

The objective of the present work is to investigate experimentally the secondary instability of the one-dimensional voidage waves occurring in two-dimensional liquid- fluidized beds and to examine the physical origin of bubbles, i.e. regions devoid of particles, which arise in fluidization. In the case of moderate-density glass particles, we observe the formation of transient buoyant blobs clearly resulting from the destabilization of the one-dimensional wavy structure. With metallic beads of the same size but larger density, the same destabilization occurs but it leads to the formation of real bubbles. Comparison with previous analytical and numerical studies is attempted. Whereas the linear and weakly nonlinear analytical models are not appropriate, the direct nonlinear simulations provide a qualitative agreement with the observed destabilization mechanism.

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