A piecewise-linear reduced-order model of squeeze-film damping for deformable structures including large displacement effects

This paper presents a reduced-order model for the Reynolds equation for deformable structure and large displacements. It is based on the model established in [11] which is piece-wise linearized using two different methods. The advantages and drawbacks of each method are pointed out. The pull-in time of a microswitch is determined and compared to experimental and other simulation data.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Diffusion of knowledge and behaviours among trainee doctors in an acute medical unit and implications for quality improvement work: a mixed methods social network analysis

Abstract: Objectives: To describe the social networks that diffuse knowledge, attitudes and behaviours relating to different domains of practice within teams of trainee doctors in an acute hospital medical setting. The domains examined were “clinical-technical”, “patient centeredness” and “organisation of work”. Design: Sequential mixed methods: i) sociocentric survey of trainee consisting of questions about which colleagues are emulated or looked to for advice, with construction of social network maps, followed by ii) semi structured interviews regarding per to peer influence, analysed using a grounded theory approach. The study took place over 24 months. Setting: An acute medical admissions unit, which receives admissions from the emergency department and primary care, in a NHS England teaching hospital. Participants: Trainee medical doctors working in five consecutive rotational teams. Surveys were done by 39 trainee doctors; then 20 different participants from a maximal diversity sample were interviewed. Results: Clinical-technical behaviours spread in a dense network with rich horizontal peer to peer connections. Patient centred behaviours spread in a sparse network. Approaches to non-patient facing work are seldom copied from colleagues. Highly influential individuals for clinical technical memes were identified; high influencers were not identified for the other domains. Conclusion: Information and influence relating to different aspects of practice have different patterns of spread within teams of trainee doctors; highly influential individuals were important only for spread of clinical-technical practice. Influencers have particular characteristics, and this knowledge could guide leaders and teachers

The Effect of Time-Delay Feedback Controller on an Electrically Actuated Resonator

This paper presents a study of the effect of a time-delay feedback controller on the dynamics of a Microelectromechanical systems (MEMS) capacitor actuated by DC and AC voltages. It is shown that negative time-delay feedback control gain can lead to an unstable system, even if AC voltage is relatively small compared to DC voltage. Perturbation method is utilized to present analytically the nonlinear dynamic characteristics of the MEMS capacitor. Agreements among the results of a shooting technique, long-time integration, basin of attraction analysis with the perturbation method are achieved

Merging parallel-plate and levitation actuators to enable linearity and tunability in electrostatic MEMS

In this study, a linear electrostatic MEMS actuator is introduced. The system consists of a MEMS cantilever beam with combined parallel-plate and electrostatic levitation forces. By using these two forcing methods simultaneously, the static response and natural frequency can be made to vary linearly with the voltage. The static response shows a linear increase of 90 nm/V and is maintained for more than 12μm of the tip displacement. The natural frequency shows a linear increase of 16 Hz/V and is maintained throughout a 2.9 kHz shift in the natural frequency. This wide range of linear displacement and frequency tunability is extremely useful for MEMS sensors and actuators, which suffer from the inherent nonlinearity of electrostatic forces. A theoretical model of the system is derived and validated with experimental data. Static response, natural frequency, and frequency response calculations are performed. Merging these two mechanisms enables high oscillation branches for a wide range of frequencies with potential applications in MEMS filters, oscillators, and sensors

Serum Macromineral Levels in Estrual, Fertile, Subfertile and Pregnant Mares Kept Under Two Different Managemental Conditions

This study was conducted on 300 mares kept under one of the two managemental conditions: field (individual management) and farm (organizational management). Mares were categorized as estrual, fertile, subfertile or pregnant. Any possible relationship between fertility and serum levels of sodium, magnesium, phosphorus, potassium and calcium was investigated. The serum sodium level differed significantly (P<0.05) among all groups of mares at both conditions, with pregnant mares having the highest and subfertile the lowest levels. Also, independent of the condition, the pregnant mares had significantly higher (P<0.05) serum potassium levels compared with subfertile ones. Serum calcium levels were significantly higher in estrual mares when compared with those of pregnant mares under farm management or subfertile mares under field conditions. In each group, mares kept under farm management had significantly higher serum magnesium levels but significantly lower serum calcium levels than those of mares kept under field. In estrual group, mares raised under field condition had significantly higher serum phosphorus levels. These results sufficiently provide the foundation for more rigorous and controlled studies to establish a firm basis for fertility versus serum-mineral-profile relationship. Moreover, due to marginally adequate serum mineral levels in mares kept under both managements, supplementation with mineral mixture was recommended for optimum fertility

Stellar Image Interpretation System using Artificial Neural Networks: Unipolar Function Case

An artificial neural network based system for interpreting astronomical images has been developed. The system is based on feed-forward Artificial Neural Networks (ANNs) with error back-propagation learning. Knowledge about images of stars, cosmic ray events and noise found in images is used to prepare two sets of input patterns to train and test our approach. The system has been developed and implemented to scan astronomical digital images in order to segregate stellar images from other entities. It has been coded in C language for users of personal computers. An astronomical image of a star cluster from other objects is undertaken as a test case. The obtained results are found to be in very good agreement with those derived from the DAOPHOTII package, which is widely used in the astronomical community. It is proved that our system is simpler, much faster and more reliable. Moreover, no prior knowledge, or initial data from the frame to be analysed is required

Towards electromechanical computation: An alternative approach to realize complex logic circuits

Electromechanical computing based on micro/nano resonators has recently attracted significant attention. However, full implementation of this technology has been hindered by the difficulty in realizing complex logic circuits. We report here an alternative approach to realize complex logic circuits based on multiple MEMS resonators. As case studies, we report the construction of a single-bit binary comparator, a single-bit 4-to-2 encoder, and parallel XOR/XNOR and AND/NOT logic gates. Toward this, several microresonators are electrically connected and their resonance frequencies are tuned through an electrothermal modulation scheme. The microresonators operating in the linear regime do not require large excitation forces, and work at room temperature and at modest air pressure. This study demonstrates that by reconfiguring the same basic building block, tunable resonator, several essential complex logic functions can be achieved. Published by AIP Publishing

Stability of Immediately Placed and Delayed Implants Using Resonance Frequency Analysis (RFA). A Systematic Review

Objectives: The aim of the present Systematic Review was to compare between immediate and delayed dental implant placement using resonance frequency analysis specifically Implant Stability Quotients (ISQ). Search methods: Search was performed in two databases (PubMed and Cochrane Library) till March 2023. Randomized clinical trials (RCTs) were included and measurements of ISQ at time of placement and time of loading were recorded. We excluded papers discussing bone grafting, orthodontic treatment and implant surface treatment. Results: Results were above ISQ threshold value of 65, with no significant difference between immediate and delayed implants. However, Immediate placement showed shorter treatment time and better esthetic outcome. Conclusion: Implant stability can be achieved with both immediate and delayed implant placement techniques

Brazil's Engagement in International Development Cooperation: The State of the Debate

The international development cooperation architecture has changed dramatically over the last decade. The global context, characterised by a lingering financial crisis and the emergence of new powers, has brought South–South Development Cooperation (SSDC) to the core of international development debate. The growing influence of emerging countries, such as the BRICS (Brazil, Russia, India, China and South Africa), as development cooperation providers requires a deeper understanding of how and to what extent these countries are promoting sustainable and inclusive development by cooperating with partners in the global South. To be able to answer these questions, the national dynamics need to be unpacked by mapping institutions, ideas, and interests informing decision-making processes, and shaping, not only policy priorities, but also the effectiveness of development cooperation. Brazil is in the spotlight and Brazilian cooperation, in all its different modalities (from technical, scientific and technological, educational, and humanitarian cooperation to contributions to international organisations, refugee support and protection, and peace operations), has risen to unprecedented levels in recent years. According to official data, Brazilian development cooperation increased from US$160 million in 2005 to more than US$900 million in 2010. In that period, the country’s technical cooperation disbursements grew almost fourfold and its humanitarian cooperation expanded from less than half a million dollars in 2005 to US$161 million in 2010. However, interviews and the current budget freeze on the Brazilian Cooperation Agency’s (ABC) activities indicate that the upward trend may have changed in the last three years.UK Department for International Developmen

Efficient Excitation of Micro/Nano Resonators and Their Higher Order Modes

We demonstrate a simple and flexible technique to efficiently activate micro/nano-electromechanical systems (MEMS/NEMS) resonators at their fundamental and higher order vibration modes. The method is based on the utilization of the amplified voltage across an inductor, L, of an LC tank resonant circuit to actuate the MEMS/NEMS resonator. By matching the electrical and mechanical resonances, significant amplitude amplification is reported across the resonators terminals. We show experimentally amplitude amplification up to twelve times, which is demonstrated to efficiently excite several vibration modes of a microplate MEMS resonator and the fundamental mode of a NEMS resonator