On the reliability of electrostatic NEMS/MEMS devices: Review of present knowledge on the dielectric charging and stiction failure mechanisms and novel characterization methodologies

This paper reviews the state of the art knowledge related to critical failure mechanisms in electrostatic micro- and nano-electromechanical systems (MEMS and NEMS) which are the dielectric charging and stiction. It describes also the recent employed nanoscale characterization techniques for these phenomena based on Kelvin probe force microscopy (KPFM) and force–distance curve measurements. The influence of relative humidity and dielectric deposition conditions on the charging/discharging processes is discussed. Moreover, different stiction mechanisms induced by electrostatic force and/or meniscus formation are analyzed. Finally, novel characterization methods are presented and used to correlate between the results from MEMS devices and metal–insulator–metal (MIM) capacitors. These methods are employed in view of application in electrostatic capacitive MEMS switches and could be easily extended to explore other NEMS/MEMS devices. The study provides an accurate understanding of the charging and stiction related failure mechanisms, presents guidelines for a proper packaging environment, and reveals precise explanations for the literature reported device level measurements of electrostatic MEMS devices.     

Variational density matrix optimization using semidefinite programming

We discuss how semidefinite programming can be used to determine the second-order density matrix directly through a variational optimization. We show how the problem of characterizing a physical or N-representable density matrix leads to matrix-positivity constraints on the density matrix. We then formulate this in a standard semidefinite programming form, after which two interior point methods are discussed to solve the SDP. As an example we show the results of an application of the method on the isoelectronic series of Beryllium.     

复合材料为模具制造商创造机遇

在这个高科技操作运行的时代,先进的金属加工技术将能满足复合材料的生产需要。航宇工业和国防工业的业务正在迅猛发展,以及重塑军事能力在武器系统的发展,这为飞机制造业开创了有利局面。对这两个行业起着重要发展作用的一项技术就是复合材料,这一般是指碳纤维材料或玻璃纤维热固性和热塑性多材料层压板。这     

A dynamical model for generating synthetic electrocardiogram signals

A dynamical model based on three coupled ordinary differential equations is introduced which is capable of generating realistic synthetic electrocardiogram (ECG) signals. The operator can specify the mean and standard deviation of the heart rate, the morphology of the PQRST cycle, and the power spectrum of the RR tachogram. In particular, both respiratory sinus arrhythmia at the high frequencies (HFs) and Mayer waves at the low frequencies (LFs) together with the LF/HF ratio are incorporated in the model. Much of the beat-to-beat variation in morphology and timing of the human ECG, including QT dispersion and R-peak amplitude modulation are shown to result. This model may be employed to assess biomedical signal processing techniques which are used to compute clinical statistics from the ECG.     

Hardware Implementation of a Fixed-Point Decoder for Low-Density Lattice Codes

Journal of Signal Processing Systems - This paper describes a field-programmable gate array (FPGA) implementation of a fixed-point low-density lattice code (LDLC) decoder where the Gaussian mixture...     

Modeling and Simulation for Transient Thermal Analyses Using a Voltage-in-Current Latency Insertion Method

This article presents a modeling and simulation method for transient thermal analyses of integrated circuits(ICs) using the original and voltage-in-current(VinC) latency insertion method(LIM). LIM-based algorithms are a set of fast transient simulation methods that solve electrical circuits in a leapfrog updating manner without relying on large matrix operations used in conventional Simulation Program with Integrated Circuit Emphasis(SPICE)-based methods which can significantly slow down the sol...     

A comparison of MOSFETs aging under d.c., a.c. and alternating stress conditions

The effects of static, alternating and dynamic stress conditions on the degradation rate of 0.8μm n- and p-channel LDD MOS transistors have systematically been investigated and compared. The shifts of the threshold voltage, transconductance, linear drain current and charge pumping current were used to monitor the transistor degradation. The results suggest that the aging induced by a dynamic stress cannot be directly explained with static stress models, essentially because it is highly dependent on a larger number of parameters (biases and durations of the top and bottom levels of the pulses, transient times). The correlation of static and dynamic stresses also clarifies the degradation mechanisms, in particular the role of hot holes in the generation of interface states.     

A survey on industrial communication networks

Industrial communication networks differ from other types of networks because these applications are responsible for the control and monitoring of a physical process. In this paper, we will summarise the requirements that users specify for these networks, present the state of art on field buses, factory and cell communication networks and indicate current research directions.     

Optimisation de ľefficacité de couplage entre un guide ďonde confiné et une fibre optique monomode par ľintermédiaire ďune lentille boule

Theoretical coupling efficiency between a channel waveguide and a single-mode optical fibre using a ball lens is optimized by varying the parameters of the optical system such as the relative position of the components, the refractive index and the size of the lens. A specific software has been used for the optimization. Numerical calculations have been done under the Gaussian approximation of the fields distributions. The losses due to waveguides misalignments with respect to their ideal position have been evaluated. All these theoretical results are compared with those obtained from buttcoupling.     

Theoretical analysis of a fractal surface radiation

We compare, in this paper, the far field radiated by two fractal distributions of current. The first one is obtained by a fractal cut following the Cantor arrangement, the second one keeps the length of each previous current element, but modifies the distance between the elements which is now taken as a constant. We establish the analytical formulations of the far field at any step n of the Cantor set. Then, we extract the array factor and we analyse and compare the following properties : convergence of the radiation pattern, wide of the main lobe, side lobes level and directivity.