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Design and demonstration of integrated micro-electro-mechanical relay circuits for VLSI applications

Design and demonstration of integrated micro-electro-mechanical relay circuits for VLSI applications

The energy-delay trade-offs (with supply-scaling) of both CMOS and MEM-relay 16-bit multipliers are shown in Figure 4-15. The CMOS multipliers reach their minimum en[r]

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Electro-Mechanical Manipulation of Mammalian Cells in Suspension

Electro-Mechanical Manipulation of Mammalian Cells in Suspension

The results presented in this thesis clearly demonstrate that ED can be used for the mechanical characterization of individual mammalian cells, using a microtechnology platform. Aided by microfabrication methods described here, we have produced ED test-devices on glass or transparent plastic (polymer) substrates (Fig. 4.1); we therefore anticipate that diverse future implementations of the methods described in this thesis will take place. We have performed a wide variety of cell- and sub-cellular manipulations: DEP and EP of cell populations, as well as ED of individual cells were all accomplished using the same device incorporating planar microelectrodes. Although similar techniques had previously been reported by others, we have here presented novel applications for each technique. As mentioned in Sect. 1.2 of this thesis, the miniaturization of existing laboratory techniques increases their efficiency and permits scale-up and automation of experiments in ever-decreasing on-chip footprints. The use of DEP in microdevices is well-established, but EP and especially ED are not as widely used. The use of combined DEP and EP for EF is a particularly good example of a widely-performed technique, which would benefit greatly from miniaturization due to the increased ability to handle and observe individual cells and fusion products. Mechanical measurements by ED are not widely- reported in either standard- or miniaturized- platforms; however, we believe that ED provides several advantages over other techniques such as OT, which we will discuss below.
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Structural, magnetic and mechanical properties of 5 µm thick SmCo films for use in Micro-Electro-Mechanical-Systems

Structural, magnetic and mechanical properties of 5 µm thick SmCo films for use in Micro-Electro-Mechanical-Systems

magnetocrystalline anisotropy [2]. Thus for applications in which very large coercivites are not needed, SmCo 7 and Sm 2 Co 17 are the phases of choice. In-plane textured SmCo 7 or Sm 2 Co 17 films have been used for biasing of yttrium iron garnet (YIG) [15], permalloy [16] and Colossal Magneto Resistance (CMR) [17] films. More recently, two prototype micro-

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Development of non-linear Electro-Thermo-Mechanical Discontinuous Galerkin formulations

Development of non-linear Electro-Thermo-Mechanical Discontinuous Galerkin formulations

However, SMP have the drawback of low strength and stiffness when they are used for structural applications. This drawback can be overcome by disperesing (distributing) continuous or discontinuous reinforcements throughout a polymer matrix, leading to Shape Memory Polymer Composites (SMPC). Meng et al. [53] have clarified that the aim of SMPC is to improve the shape memory recovery stress and the mechanical properties in addition to act as triggering mechanisms under light, moisture, electricity, or magnetic field, but also to tune the transition temperature. In particular, the kinds of reinforcement that we are interested in are nanowires, carbon nanotubes, and continuous carbon fibers dispersed throughout a shape memory polymer which results in composite materials with high stiff- ness and strength to weight ratios. The polymer matrix indeed avoids catastrophic failure due to fiber breaking, and the existence of the carbon fibers enhances strength and stiffness. Moreover, carbon fibers exhibit conductivity which can be exploited as a shape memory triggering mechanism. The range of composite material electrical conductivity can be con- trolled by the amount of carbon fibers, and the increase of temperature required to trigger the Shape Memory effect is obtained through Joule effect by applying an electric current, which makes them favorable and meet the particular requirements for many applications in which applying an external heat is difficult. Henceforth SMPC are the prime candidate materials for the area of deployable space structures (intelligent structures). A review con-
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Fault prognostics of micro-electro-mechanical systems using particle filtering

Fault prognostics of micro-electro-mechanical systems using particle filtering

Keywords: Prognostics and health management, micro-electro-mechanical system, fault prognostics, remaining useful life, particle filter. 1. INTRODUCTION Micro-Electro-Mechanical Systems (MEMS) are micro- systems that integrate mechanical components using elec- tricity as source of energy in order to perform measurement functions and/or operating in structure having micromet- ric dimensions. In the past few years, MEMS devices gained wide-spread acceptance in several industrial seg- ments including aerospace, automotive, medical and even military applications, where they contribute to important functions. The most known applications of MEMS are accelerometers for automotive (airbag) applications, gy- roscopes for mobiles phones, pressure sensors for engine management and micro-mirror arrays for display applica- tions. Nevertheless, the reliability of MEMS is considered as a major obstacle for their development (Medjaher et al. (2014)). They suffer from numerous failure mechanisms which impact their performance, reduce their lifetime, and the availability of systems in which they are used (Huang et al. (2012); Hartzell et al. (2011); Merlijn van Spengen (2003); Li and Jiang (2008)). This analysis shows the need to monitor their behavior, assess their health state and an- ticipate their failures before their occurrence. These tasks can be done by using Prognostics and Health Management (PHM) approaches, and this is the aim of this paper. PHM is the combination of seven layers that collectively enable linking failure mechanisms with life management
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Knowledge-Based Multidisciplinary Sizing and Optimization of Embedded Mechatronic Systems - Application to Aerospace Electro-Mechanical Actuation Systems

Knowledge-Based Multidisciplinary Sizing and Optimization of Embedded Mechatronic Systems - Application to Aerospace Electro-Mechanical Actuation Systems

in order to select the best among them. To analyse and select a design solution, a sizing process is necessary to evaluate the necessary physical characteristics of the equipment and its components (mass, geometric integration, cost...). This can be achieved using numerical methods like system analysis and optimization. Mechatronic systems have several operational (take-off, cruise...) and failure modes (power loss, jamming...). They have to be taken into account during the sizing process to avoid non-compliant designs. Besides, a mechatronic system is defined by a physical or power architecture where various components are interfaced. Therefore, their design must consider the potential interactions and couplings between the components. These coupling can become more complex because components come from several domains such as electronic (power control unit), electrical (electrical motor) and mechanical (ball screw, spur gear, rod ends, housing and thrust bearings) domains and therefore solicit different engineering teams (power electronics, machine design, mechanical design...). Furthermore, the physical laws that govern the components behaviour belong to different physical disciplines like electromagnetics (electromagnetic torque, iron losses...) , electricity (Joule losses), structural mechanics (vibrations) or heat transfer (component temperatures) for instance. In some applications different physics are coupled like between fluid dynamics and structural mechanics (wind turbine blade design) or electromagnetics and heat transfer (electrical machine design). Additionally, time constants and geometric elements of the different physics show a large panel of scales (size: micro-controller chip vs actuator housing or time constant: power electronics switching period vs actuator thermal time constant).
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Demonstration of Integrated Mico-Electro-Mechanical Switch Circuits for VLSI Applications

Demonstration of Integrated Mico-Electro-Mechanical Switch Circuits for VLSI Applications

The inverter, carry-generation circuit, oscillator, and DAC demonstrate the abili- ty of MEM switches to compute and communicate, to both perform logic func- tions and to drive loads. Figure 7.9.5 shows a MEM switch-based latch and measured transient waveforms demonstrating correct operation in both the opaque and transparent states. The output of the latch is isolated from the inputs with two resistively-loaded inverters that also drive the feedback keeper switch. Like in CMOS, a cascade of two latches can be used to create a flip-flop. Given its low leakage current [4], the switch is also well suited for DRAMs. Figure 7.9.6 shows a 10-bit DRAM column composed of MEM switches. The memory is constructed in a NAND configuration. The bit read line (BL RD ) is pre- charged low and the word read line (WL RD [n]) is an active low signal that dis- ables the read pull-up path unless the stored bit is a “1”. The additional path of nominally on switches allows the memory to perform a read operation in a sin- gle mechanical turn-on delay (for decoding) plus a mechanical turn-off delay. Since the turn-off delay is much smaller than the turn-on delay, this configura- tion results in reduced read delay. Figure 7.9.6 also shows the measured results for the 10-bit memory cell, which was fully integrated except for (due to lack of vias) the wires between the drain of the storage device and the gate of the mem- ory device (Fig. 7.9.7). Due to measurement setup limitations, the pre-charge switch is bypassed with a 100k Ω pull-down resistor. The waveforms show a simultaneous memory write and read of the same bit.
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Multi-MHz micro-electro-mechanical sensors for atomic force microscopy

Multi-MHz micro-electro-mechanical sensors for atomic force microscopy

1. Introduction Scanning probe microscopy (SPM) has been one of the most important instrumental discoveries during the last quarter of the last century [1]. In particular, atomic force microscopy (AFM) is a cross-disciplinary technique able to provide sample morphology down to the atomic scale [2]. This has been at the origin of, and constantly supports the development of nano-sciences, information technologies, micro-nanotechnologies and nano-biology. Dynamic mode AFM has a unique capability of characterizing soft and biological materials like molecular structures in native-like and functional conditions [3, 4, 5, 6]. Interaction forces between the AFM oscillating tip and the sample surface can be kept in the 10 pN range, ensuring non-damaging observations. Beyond providing topography images by scanning XY axes, AFM through Z spectroscopy gives access to advanced analysis of tip-sample interactions and to rheological information like material elasticity and mechanical dissipation [7, 8, 9]. Increasing the AFM probe resonance frequency is desirable for such applications. First, it contributes to increase the measurement bandwidth of the AFM, one of the key parameters for time-resolved experiments and high-speed imaging, which remains a huge expectation in the field. Second, it allows the investigation of the dynamic behavior of material viscoelasticity over an extended frequency range. The mainstream option to achieve this goal consists in miniaturizing the conventional AFM probe based on the flexural mode cantilever to raise the resonance frequency. Downscaled cantilevers are now commercially available resonating in the range 1-5 MHz [10]. During the last decade, they have been employed successfully in high-speed AFM instruments [11], leading to impressive video rate images and to direct observations of the dynamic
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Shape and Topology Optimization for electro-mechanical energy converters

Shape and Topology Optimization for electro-mechanical energy converters

As was reviewed in Chapter 1, numerous techniques have been proposed over the years to differentiate either the discretized algebraic system of the PDEs that govern the physical problem, or on the other hand, their variational form, mostly arising in the area of structural mechanics. Applications in other disciplines such as electromagnetics have also been proposed, but have been limited to problems expressed in terms of a scalar potential, leaving aside the problem of handling vector unknown fields. We have therefore derived a general framework for anal- ysis which extends the calculation of sensitivity to the vector field case, for both static and time-harmonic PDEs, in a unified and elegant fashion. In addition we are able to recover a number of results, previously obtained by other authors as particular cases. The proposed framework, which is based on the general differen- tial geometry framework, expresses the sensitivity at a continuous level, prior to discretization, as a Lie derivative. Theoretical formulas for shape sensitivity are derived and described in detail, following both the direct and the adjoint approach. They are reformulated with conventional tensor and vector analysis notations. We have also derived an efficient method for the construction of the velocity field of the auxiliary flow that represents the shape modification of the system. Thus one can express the sensitivity locally as a volume integral over a single layer of finite elements connected to both sides of the surfaces undergoing shape modification. The complete and general automatic sensitivity computation tool has been val-
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POM Mechanical Properties

POM Mechanical Properties

Figure 9 : amorphous layer thickness as a function of molecular weight (l a -M W ) and mechanical behavior (ductile, ductile brittle transition and brittle region). Conclusion The poly(oxy methylene) could be considered as high performance polymer due to its high mechanical properties. At short term use, it presents a high elastic properties as a result of the high crystalline fraction. Indded, despite the fact that the amorphous phase is in rubber-like state at room temperature, POM still have an elastic modlus af about 3 to 4 GPa. Indeed the elastic modulus of POM crystalline phase made of stiff crystalline lamellae organized either in spherulitic or oriented morphology will more than compensate for the weak amorphous phase. However, at room temperature, POM shows highly brittle behavior, which could be enhanced by using rubber reinforcing particles such as thermo plastic poly(urethane) or rubber particles.
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Mechanical and structural properties of ice

Mechanical and structural properties of ice

s Modulus (lb. ) Axis of c r ys tals horizontal Axis of crystals vertical Temperature One pound loads added at intervals of 5 sec.. The.[r]

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Electro-thermally driven microgrippers for micro-electro-mechanical systems applications

Electro-thermally driven microgrippers for micro-electro-mechanical systems applications

/ La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur. For the publisher’[r]

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View of Mechanical ventilation and withdrawal

View of Mechanical ventilation and withdrawal

1 inserm U956, groupe hospitalier pitié-salpêtrière, paris, France 2 service de pneumologie et réanimation médicale,.. groupe hospitalier pitié-salpêtrière, paris, France.[r]

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View of Mechanical ventilation and weaning

View of Mechanical ventilation and weaning

Patients et Méthodes : We compared 2 periods including 2 prospec- tive cohort studies on weaning performed in a medical ICU of a tea- ching hospital in France. The main objective of the first cohort was to identify patients at high risk for extubation failure whereas prophylac- tic NIV was never applied. In this study, patients at high risk for extu- bation failure were those with an age above 65 years and those with any underlying chronic cardiac or respiratory disease. In the second cohort prophylactic NIV was systematically applied after planned extu- bation in all patients considered at high risk for extubation failure according to our previous study. NIV was delivered immediately after extubation for at least 8 hours during the first 24 hours following extu- bation. Extubation failure was defined by the need for reintubation within the 7 days following planned extubation.
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Thermo-mechanical Effects in Mechanical Polishing of Natural Fiber Composites

Thermo-mechanical Effects in Mechanical Polishing of Natural Fiber Composites

Polishing NFRP composites is not yet investigated to date. However, some works were interested in the tribological behavior of NFRP composites using the pin-on-disc tribo test machine [16–21]. Indeed, it has been shown a better wear and frictional performance under wet contact condition compared to dry. The wear mechanisms, in this case, were predominated by micro and macro-cracks in the polymer regions and debonding of natural fibers [16]. It has been reported that the fiber orientation has a significant effect on wear and frictional performances in addition to the contact interface temperature [17]. The fiber content also determines the regions where an NFRP wears. Wear rates are drastically decreased with increasing fibers content [18]. The literature also indicates the importance of the fiber treatment; e.g. NaOH-treated NFRPs demonstrate improved wear performance as compared to their untreated counterparts [20]. Globally, the incorporation of natural fiber into polymer matrix improves significantly the tribological behavior of the composites by increasing the wear resistance and reducing the friction coefficient [19,21]. However, a pin-on-disc study remains a macro-tribological technique, as it is mainly based on sliding mechanism between two surfaces. It ignores the thermomechanical behavior of NFRP composites during material removal. Given the material properties (low thermal conductivity compared to metals) and high heat generation during material removal processes, consideration of thermomechanical effects is essential towards understanding the mechanisms of material removal in NFRPs.
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Characterisation of ground thermal and thermo-mechanical behaviour for shallow geothermal energy applications

Characterisation of ground thermal and thermo-mechanical behaviour for shallow geothermal energy applications

Figure 26. Evolution of volumetric strain with clay activity (adapted from Reference [ 26 ] using data from References [ 198 , 212 , 214 , 217 , 219 , 220 , 222 – 224 ]). 6.3.2. THM Response by Shear Tests The direct shear test measures the shear strength properties of soils or soft rocks along a predetermined plane. The test is carried out on a soil sample placed in a square cross-section metal box. The box is split horizontally at mid-height and a small clearance is kept between the two halves of the box. The soil sample is sheared by moving the top half of the box relative to the bottom half. The rate of strain can be varied to obtain drained or undrained conditions, depending on whether the strain is applied slowly enough to prevent pore-water pressure build-up or not. However, a specimen’s pore pressure cannot be measured in standard direct shear apparatus. The adaptation of this test to non-isothermal conditions is relatively simple and the main concern is to maintain constant temperature conditions during the test. Due to its configuration, this test has been used to investigate the behaviour of the pile-soil interface, which is particularly important to assess the response of floating energy piles. Sand-concrete and clay-concrete interfaces were tested in this way under constant normal load and constant normal stiffness conditions monotonically and cyclically.
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Physical and Mechanical Properties of CrAlN and CrSiN Ternary Systems for Wood Machining Applications

Physical and Mechanical Properties of CrAlN and CrSiN Ternary Systems for Wood Machining Applications

of 10 min). The CrN ‘A’ and CrAlN coatings’ thickness and compositions were determined by SEM (JEOL JSM-5900 LV) equipped with an energy dispersive spectrometry (EDS). The CrN ‘B’ and CrSiN films’ thickness was measured with a 2D profilometer (Dektak 3030). Hardness measurement was per- formed using a CSM Nano Hardness Tester with a Berkovich tip in a dynamical mode analysis (maximum load reached of 10 mN, the sinus amplitude was fixed at 1 mN with a frequency of 1 Hz). Wear tests were realized by using a conventional pin-on-disc tribometer (X85WMoCrV6542 steel as substrate and alumina ball (5 mm of diameter) as counterpart, with a normal load of 25 N). Before deposition, all the targets and the samples were etched in Ar plasma by RF and DC discharges, respectively.
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Thermo-mechanical recycling of rubber: Relationship between material properties and specific mechanical energy

Thermo-mechanical recycling of rubber: Relationship between material properties and specific mechanical energy

arguments for this are to follow. The evolution of the temperatures along the cones for the tests with 8 and 16 sequences are shown in Figures 14 and 15 respectively. Since similar temperature evolutions were recorded in the stator and rotor, although at different levels, only the temperatures from the stator are shown. The comparison of the three trials for the first 4 sequences shows very similar temperature variations. This attests to the good reproducibility of the process. Sequences 5 to 8 (Figure 14) continued the trend observed for the first 4. The temperatures measured by the thermocouples located at the bottom of the cones, TS1 and TS7, continued to decrease on average whereas TS15 was oscillating between 25°C and 30°C. Sequences 9 to 16 depict a change in the tendency. Temperatures recorded by TS1 and TS7 reached a minimum at around 21°C in the 8 th sequence before increasing again up to 29°C for TS1 and 25°C for TS7. The temperature measured by TS15 continued to oscillate but increased slightly over time. The maximum temperature for the 1 st sequence was 27°C and 34°C for the last one. This could partly be explained by the continuous self-heating of the rubber and the convection of heat along the steel since the cooling system did not permit the produced heat to dissipate instantaneously.
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Multiscale tribo-mechanical analysis of natural fiber composites for manufacturing applications

Multiscale tribo-mechanical analysis of natural fiber composites for manufacturing applications

Fig. 6 presents the elastic modulus from nanoindentation tests for flax fibers and PP matrix. It can be seen the significant variability of elastic modulus for flax fibers. This is mainly due to the heterogeneous cellulosic structure of flax fibers as explained in Section 2 . Therefore, the nano- indentation response of flax fibers is significantly dependent on the nanoindentation location inside the fiber cross-section. Moreover, the elastic modulus of flax fibers decreases significantly by increasing the penetration depth. This is the sign that the amorphous non-cellulosic constituents of flax fibers have the main contribution at this contact scales. Indeed, the cross-section size of cellulose micro fibrils is around 1 –4 nm, and the cross-section of cellulose mesofibrils (i.e. bundle of microfibrils) is around 100–300 nm [ 28 ] which is in the same magnitude as the tip indenter radius (100 nm). As the cellulosic micro fibrils are almost perpendicular to the fiber cross-section [ 15 ], increasing the con- tact depth (i.e. increasing the applied load) during nanoindentation makes the cellulose microfibrils transversally deviated from the inden- tation path. This leads to avoid the contact with cellulosic micro fibrils and then favor the contact with the amorphous non-cellulosic polymers (hemicellulose and lignin). Thus, increasing the cutting depth during the indentation generates elastic modulus values near to those of hemicel- lulose and lignin that are around 3.5–8.0 GPa for hemicellulose and 2–6.7 GPa for lignin [ 29 ]. On the other hand, elastic modulus values of PP matrix show neither high variation nor high variability because of its homogeneity.
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Multiscale tribo-mechanical analysis of natural fiber composites for manufacturing applications

Multiscale tribo-mechanical analysis of natural fiber composites for manufacturing applications

Fig. 6 presents the elastic modulus from nanoindentation tests for flax fibers and PP matrix. It can be seen the significant variability of elastic modulus for flax fibers. This is mainly due to the heterogeneous cellulosic structure of flax fibers as explained in Section 2 . Therefore, the nano- indentation response of flax fibers is significantly dependent on the nanoindentation location inside the fiber cross-section. Moreover, the elastic modulus of flax fibers decreases significantly by increasing the penetration depth. This is the sign that the amorphous non-cellulosic constituents of flax fibers have the main contribution at this contact scales. Indeed, the cross-section size of cellulose micro fibrils is around 1 –4 nm, and the cross-section of cellulose mesofibrils (i.e. bundle of microfibrils) is around 100–300 nm [ 28 ] which is in the same magnitude as the tip indenter radius (100 nm). As the cellulosic micro fibrils are almost perpendicular to the fiber cross-section [ 15 ], increasing the con- tact depth (i.e. increasing the applied load) during nanoindentation makes the cellulose microfibrils transversally deviated from the inden- tation path. This leads to avoid the contact with cellulosic micro fibrils and then favor the contact with the amorphous non-cellulosic polymers (hemicellulose and lignin). Thus, increasing the cutting depth during the indentation generates elastic modulus values near to those of hemicel- lulose and lignin that are around 3.5–8.0 GPa for hemicellulose and 2–6.7 GPa for lignin [ 29 ]. On the other hand, elastic modulus values of PP matrix show neither high variation nor high variability because of its homogeneity.
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