A Novel Piezoelectric Microtransformer for Autonmous Sensors Applications
This work relates to a novel piezoelectric transformer to be used in an autonomous sensor unit, possibly in conjunction with a RF-MEMS retro-modulator.
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Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.
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Optimization of efficiency and energy density of passive micro fuel cells and galvanic hydrogen generators
A PEM micro fuel cell system is described which is based on self-breathing PEM micro fuel cells in the power range between 1 mW and 1W. Hydrogen is supplied with on-demand hydrogen production with help of a galvanic cell, that produces hydrogen when Zn reacts with water. The system can be used as a battery replacement for low power applications and has the potential to improve the run time of autonomous systems. The efficiency has been investigated as function of fuel cell construction and tested for several load profiles.
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Design and Fabrication of Acoustic Wave Actuated Microgenerator for Portable Electronic Devices
The past few years have seen an increasing focus on energy harvesting issue, including power supply for portable electric devices. Utilize scavenging ambient energy from the environment could eliminate the need for batteries and increase portable device lifetimes indefinitely. In addition, through MEMS technology fabricated micro-generator could easy integrate with these small or portable devices. Several different ambient sources, including solar, vibration and temperature effect, have already exploited [1-3]. Each energy source should be used in suitable environment, therefore to produce maximum efficiency. In this paper, we present an acoustic wave actuated micro-generator for power system by using the energy of acoustic waves, such as the sound from human voices or speakerphone, to actuate a MEMS-type electromagnetic transducer. This provides a longer device lifetime and greater power system convenience. Moreover, it is convenient to integrate MEMS-based microgenerators with small or porta le devices
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Package Hermeticity Testing with Thermal Transient Measurements
The rapid incursion of new technologies such as MEMS and smart sensor device manufacturing requires new tailor-made packaging designs. In many applications these devices are exposed to humid environments. Since the penetration of moisture into the package may result in internal corrosion or shift of the operating parameters, the reliability testing of hermetically sealed packages has become a crucial question in the semiconductor industry.
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Micro-tensile tests on micromachined metal on polymer specimens: elasticity, plasticity and rupture
This study is focused on the mechanical characterization of materials used in microelectronic and micro- electromechanical systems (MEMS) devices. In order to determine their mechanical parameters, a new deformation bench test with suitable micromachined specimens have been developed. Uniaxial tensile tests were performed on "low cost" specimens, consisting in electroplated thin copper films and structures, deposited on a polimide type substrate. Moreover, a cyclic mechanical actuation via piezoelectric actuators was tested on the same deformation bench. These experiments validate the device for performing dynamic characterization of materials, and reliability studies of different microstructures.
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Open Ended Microwave Oven for Packaging
A novel open waveguide cavity resonator is presented for the combined variable frequency microwave curing of bumps, underfills and encapsulants, as well as the alignment of devices for fast flip-chip assembly, direct chip attach (DCA) or wafer-scale level packaging (WSLP). This technology achieves radio frequency (RF) curing of adhesives used in microelectronics, optoelectronics and medical devices with potential simultaneous micron-scale alignment accuracy and bonding of devices. In principle, the open oven cavity can be fitted directly onto a flip-chip or wafer scale bonder and, as such, will allow for the bonding of devices through localised heating thus reducing the risk to thermally sensitive devices. Variable frequency microwave (VFM) heating and curing of an idealised polymer load is numerically simulated using a multi-physics approach. Electro-magnetic fields within a novel open ended microwave oven developed for use in micro-electronics manufacturing applications are solved using a de icated Yee scheme finite-difference time-domain (FDTD) solver. Temperature distribution, degree of cure and thermal stresses are analysed using an Unstructured Finite Volume method (UFVM) multi-physics package. The polymer load was meshed for thermophysical analysis, whilst the microwave cavity - encompassing the polymer load - was meshed for microwave irradiation. The two solution domains are linked using a cross-mapping routine. The principle of heating using the evanescent fringing fields within the open-end of the cavity is demonstrated. A closed loop feedback routine is established allowing the temperature within a lossy sample to be controlled. A distribution of the temperature within the lossy sample is obtained by using a thermal imaging camera.
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Mechanical Fatigue on Gold MEMS Devices: Experimental Results
The effect of mechanical fatigue on structural performances of gold devices is investigated. The pull-in voltage of special testing micro-systems is monitored during the cyclical load application. The mechanical collapse is identified as a dramatic loss of mechanical strength of the specimen. The fatigue limit is estimated through the stair-case method by means of the pull-in voltage measurements. Measurements are performed by means of the optical interferometric technique.
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Testability of Reversible Iterative Logic Arrays
Iterative Logic Arrays (ILAs) are ideal as VLSI sub-systems because of their regular structure and its close resemblance with FPGAs (Field Programmable Gate Arrays). Reversible circuits are of interest in the design of very low power circuits where energy loss implied by high frequency switching is not of much consideration. Reversibility is essential for Quantum Computing. This paper examines the testability of Reversible Iterative Logic Arrays (ILAs) composed of reversible k-CNOT gates. For certain ILAs it is possible to find a test set whose size remains constant irrespective of the size of the ILA, while for others it varies with array size. Former type of ILAs is known as Constant-Testable, i.e. C-Testable. It has been shown that Reversible Logic Arrays are C-Testable and size of test set is equal to number of entries in cells truth table implying that the reversible ILAs are also Optimal-Testable, i.e. O-Testable. Uniform-Testability, i.e. U-Testability has been defined and Reversible Heterogeneous ILAs have been characterized as U-Testable. The test generation problem has been shown to be related to certain properties of cycles in a set of graphs derived from cell truth table. By careful analysis of these cycles an efficient test generation technique that can be easily converted to an ATPG program has been presented for both 1-D and 2D ILAs. The same algorithms can be easily extended for n-Dimensional Reversible ILAs.
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Fast Monte Carlo Estimation of Timing Yield: Importance Sampling with Stochastic Logical Effort (ISLE)
In the nano era in integrated circuit fabrication technologies, the performance variability due to statistical process and circuit parameter variations is becoming more and more significant. Considerable effort has been expended in the EDA community during the past several years in trying to cope with the so-called statistical timing problem. Most of this effort has been aimed at generalizing the static timing analyzers to the statistical case. In this paper, we take a pragmatic approach in pursuit of making the Monte Carlo method for timing yield estimation practically feasible. The Monte Carlo method is widely used as a golden reference in assessing the accuracy of other timing yield estimation techniques. However, it is generally believed that it can not be used in practice for estimating timing yield as it requires too many costly full circuit simulations for acceptable accuracy. In this paper, we present a novel approach to constructing an improvedMonte Carlo estimator for timing yield which provides the same accuracy as the standard Monte Carlo estimator, but at a cost of much fewer full circuit simulations. This improved estimator is based on a novel combination of a variance reduction technique, importance sampling, and a stochastic generalization of the logical effort formalism for cheap but approximate delay estimation. The results we present demonstrate that our improved yield estimator achieves the same accuracy as the standard Monte Carlo estimator at a cost reduction reaching several orders of magnitude.
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Fusion d'images: application au contrôle de la distribution des biopsies prostatiques
This paper is about the application of a 3D ultrasound data fusion technique to the 3D reconstruction of prostate biopies in a reference volume. The method is introduced and its evaluation on a series of data coming from 15 patients is described.
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Fuzzy Feedback Scheduling of Resource-Constrained Embedded Control Systems
The quality of control (QoC) of a resource-constrained embedded control system may be jeopardized in dynamic environments with variable workload. This gives rise to the increasing demand of co-design of control and scheduling. To deal with uncertainties in resource availability, a fuzzy feedback scheduling (FFS) scheme is proposed in this paper. Within the framework of feedback scheduling, the sampling periods of control loops are dynamically adjusted using the fuzzy control technique. The feedback scheduler provides QoC guarantees in dynamic environments through maintaining the CPU utilization at a desired level. The framework and design methodology of the proposed FFS scheme are described in detail. A simplified mobile robot target tracking system is investigated as a case study to demonstrate the effectiveness of the proposed FFS scheme. The scheme is independent of task execution times, robust to measurement noises, and easy to implement, while incurring only a small overhead.
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Neural Feedback Scheduling of Real-Time Control Tasks
Many embedded real-time control systems suffer from resource constraints and dynamic workload variations. Although optimal feedback scheduling schemes are in principle capable of maximizing the overall control performance of multitasking control systems, most of them induce excessively large computational overheads associated with the mathematical optimization routines involved and hence are not directly applicable to practical systems. To optimize the overall control performance while minimizing the overhead of feedback scheduling, this paper proposes an efficient feedback scheduling scheme based on feedforward neural networks. Using the optimal solutions obtained offline by mathematical optimization methods, a back-propagation (BP) neural network is designed to adapt online the sampling periods of concurrent control tasks with respect to changes in computing resource availability. Numerical simulation results show that the proposed scheme can reduce the computational overhead significantly while delivering almost the same overall control performance as compared to optimal feedback scheduling.
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From a set of parts to an indivisible whole. Part III: Holistic space of multi-object relations
The previously described methodology for hierarchical grouping of objects through iterative averaging has been used for simulation of cooperative interactions between objects of a system with the purpose of investigation of the conformational organization of the system. Interactions between objects were analyzed within the space of an isotropic field of one of the objects (drifter). Such an isotropic field of an individual object can be viewed as a prototype of computer ego. It allows visualization of a holistic space of multi-object relations (HSMOR) which has a complex structure depending on the number of objects, their mutual arrangement in space, and the type of metric used for assessment of (dis)similarities between the objects. In the course of computer simulation of cooperative interactions between the objects, only those points of the space were registered which corresponded to transitions in hierarchical grouping. Such points appeared to aggregate into complex spatial structures determining a unique internal organization of a respective HSMOR. We describe some of the peculiarities of such structures, referred to by us as attractor membranes, and discuss their properties. We also demonstrate the peculiarities of the changing of intergroup similarities which occurs when a drifter infinitely moves away from the fixed objects.
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Control-Scheduling Codesign: A Perspective on Integrating Control and Computing
Despite rapid evolution, embedded computing systems increasingly feature resource constraints and workload uncertainties. To achieve much better system performance in unpredictable environments than traditional design approaches, a novel methodology, control-scheduling codesign, is emerging in the context of integrating feedback control and real-time computing. The aim of this work is to provide a better understanding of this emerging methodology and to spark new interests and developments in both the control and computer science communities. The state of the art of control-scheduling codesign is captured. Relevant research efforts in the literature are discussed under two categories, i.e., control of computing systems and codesign for control systems. Critical open research issues on integrating control and computing are also outlined.
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Atlas-Based Prostate Segmentation Using an Hybrid Registration
Purpose: This paper presents the preliminary results of a semi-automatic method for prostate segmentation of Magnetic Resonance Images (MRI) which aims to be incorporated in a navigation system for prostate brachytherapy. Methods: The method is based on the registration of an anatomical atlas computed from a population of 18 MRI exams onto a patient image. An hybrid registration framework which couples an intensity-based registration with a robust point-matching algorithm is used for both atlas building and atlas registration. Results: The method has been validated on the same dataset that the one used to construct the atlas using the "leave-one-out method". Results gives a mean error of 3.39 mm and a standard deviation of 1.95 mm with respect to expert segmentations. Conclusions: We think that this segmentation tool may be a very valuable help to the clinician for routine quantitative image exploitation.
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Problems of robustness for universal coding schemes
The Lempel-Ziv universal coding scheme is asymptotically optimal for the class of all stationary ergodic sources. A problem of robustness of this property under small violations of ergodicity is studied. A notion of deficiency of algorithmic randomness is used as a measure of disagreement between data sequence and probability measure. We prove that universal compressing schemes from a large class are non-robust in the following sense: if the randomness deficiency grows arbitrarily slowly on initial fragments of an infinite sequence then the property of asymptotic optimality of any universal compressing algorithm can be violated. Lempel-Ziv compressing algorithms are robust on infinite sequences generated by ergodic Markov chains when the randomness deficiency of its initial fragments of length $n$ grows as $o(n)$.
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Range Medians
We study a generalization of the classical median finding problem to batched query case: given an array of unsorted $n$ items and $k$ (not necessarily disjoint) intervals in the array, the goal is to determine the median in {\em each} of the intervals in the array. We give an algorithm that uses $O(n\log n + k\log k \log n)$ comparisons and show a lower bound of $Ω(n\log k)$ comparisons for this problem. This is optimal for $k=O(n/\log n)$.
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Collaborative Virtual Queue: Fair Management of Congested Departure Operations and Benefit Analysis
Due to the stochastic nature of departure operations, working at full capacity makes major US airports very sensitive to uncertainties. Consequently, airport ground operations face critically congested taxiways and long runway queues. In this report, we show how improved management of departure operations from the ready-to-push-back time to the wheels-off time can potentially yield significant benefits to airlines and air traffic services. We develop a Collaborative Virtual Queue to enable better optimization capabilities during congested situations while taking into account the laissez-faire competitive environment. Results are evaluated using a departure system model, validated using current statistics and previous studies. First, the Collaborative Virtual Queue enables keeping aircraft away from runway queues, which increases wheels-off time predictability. Second, holding aircraft enables last-minute intra-airline flight switching. This creates new optimization capabilities for airlines i.e. it gives airlines the flexibility to prioritize their flight sequence in real-time. These capabilities are illustrated by the trade-off between minimizing the average passenger waiting time and minimizing the level of unfairness between aircraft of the same airline. For instance, airlines could choose to decrease by up to 15% their average passenger waiting time by prioritizing heavy planes over small planes when the taxiway system is congested.
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