Dynamic Power Supply Current Testing of CMOS SRAMs

We describe the design and implementation of a dynamic power supply current sensor which is used to detect SRAM faults such as disturb faults as well as logic cell faults. A formal study is presented to assess the parameters that influence the sensor design. The sensor detects faults by detecting abnormal levels of the power supply current. The sensor is embedded in the SRAM and offers on-chip detectability of faults. The sensor detects abnormal dynamic current levels that result from circuit defects. If two or more memory cells erroneously switch as a result of a write or read operation, the level of the dynamic power supply current is elevated. The sensor can detect this elevated value of the dynamic current. The dynamic power supply current sensor can supplement the observability associated with any test algorithm by using the sensor as a substitute for the read operations. This significantly reduces the test length and the additional observability enhances defect coverages.     

Misfit Layer Compounds: A Platform for Heavily Doped 2D Transition Metal Dichalcogenides

Transition metal dichalcogenides (TMDs) display a rich variety of instabilities such as spin and charge orders, Ising superconductivity, and topological properties. Their physical properties can be controlled by doping in electric double-layer field-effect transistors (FET). However, for the case of single layer NbSe₂, FET doping is limited to ≈ 1 × 10¹⁴ cm⁻², while a somewhat larger charge injection can be obtained via deposition of K atoms. Here, by performing angle-resolved photoemission spectroscopy, scanning tunneling microscopy, quasiparticle interference measurements, and first-principles calculations it is shown that a misfit compound formed by sandwiching NbSe₂ and LaSe layers behaves as a NbSe₂ single layer with a rigid doping of 0.55–0.6 electrons per Nb atom or ≈ 6 × 10¹⁴ cm⁻². Due to this huge doping, the 3 × 3 charge density wave is replaced by a 2 × 2 order with very short coherence length. As a tremendous number of different misfit compounds can be obtained by sandwiching TMDs layers with rock salt or other layers, this work paves the way to the exploration of heavily doped 2D TMDs over an unprecedented wide range of doping.     

Editorial: Mobile Networks in the Era of Big Data

Mobile Networks and Applications -     

Investigation of microstructure-property relantionships of magnesia-hercynite refractory composites by a refined digital image correlation technique

Industrial magnesia-spinel bricks destined for thermal shock applications often show more flexibility and improved crack growth resistance. Components from the spinel structure group are usually added to promote microcracking coming from thermal expansion mismatch. This leads to the development of toughening mechanisms that are very effective in improving the crack propagation resistance.Magnesia-hercynite composites were investigated in order to highlight their fracture process, with regard to their microstructure, by using Digital Image Correlation (DIC). The direct measurement of displacement fields between digital images of the reference state and the deformed one has provided valuable information on material deformation during loading. The aim of this work was to investigate the fracture behaviour of refractories through the coupling of the Wedge Splitting Test (WST) and DIC. By using a refined DIC process transformation taking into account a discontinuity of displacement, called 2P-DIC, a more effective characterisation of the fracture behaviour was achieved.     

New measures for robustness in linear multivariable feedback systems

New measures for robustness are proposed for linear multivariable control systems. A new theorem is presented to account for the controllability of systems that contain an integrating element, in the presence of additive uncertainties. The theorem leads to the definition of a sufficient condition for robust integral controllability: robustness margin (RM). The ratio of robustness margins for competing control or processs structures can be used to discriminate between these structures. These measures are useful, especially in design stages, since their calculation depends only on steady state information. Applications to several published distillation systems show the merits of these robustness measures.     

Testing of static random access memories by monitoring dynamic power supply current

This article presents a correlation between dynamic power supply current and pattern sensitive faults in SRAMs. It is shown that the dynamic power supply current provides a window for observing the internal switching behavior of the memory cells. Switching of the logic state of a memory cell results in a transient current pulse in the power supply rails. A new current-testable SRAM structure is presented which can be used to isolate normal current transients from those resulting from pattern sensitivity. The new structure differs from traditional SRAM structures only in the way that power is distributed to the cells. The new structure allows for very high coverages of disturb-type pattern sensitivity using a simple algorithm of length 5n where n is the number of cells.     

First-Principles Study of Electronic Structure,Mechanical, and Thermoelectric Properties of Ternary Palladates CdPd<Subscript>3</Subscript>O<Subscript>4</Subscript> and TlPd<Subscript>3</Subscript>O<Subscript>4</Subscript>

Ternary palladates CdPd₃O₄ and TlPd₃O₄ have been studied theoretically using the generalized gradient approximation (GGA), modified Becke–Johnson, and spin–orbit coupling (GGA–SOC) exchange–correlation functionals in the density functional theory (DFT) framework. From the calculated ground-state properties, it is found that SOC effects are dominant in these palladates. Mechanical properties reveal that both compounds are ductile in nature. The electronic band structures show that CdPd₃O₄ is metallic, whereas TlPd₃O₄ is an indirect-bandgap semiconductor with energy gap of 1.1 eV. The optical properties show that TlPd₃O₄ is a good dielectric material. The dense electronic states, narrow-gap semiconductor nature, and Seebeck coefficient of TlPd₃O₄ suggest that it could be used as a good thermoelectric material. The magnetic susceptibility calculated by post-DFT treatment confirmed the paramagnetic behavior of these compounds.     

Assessing the reTweet proneness of tweets: predictive models for retweeting

The problem of assessing the mechanisms underlying the phenomenon of virality of social network posts is of great value for many activities, such as advertising and viral marketing, influencing and promoting, early monitoring and emergency response. Among the several social networks, Twitter.com is one of the most effective in propagating information in real time, and the propagation effectiveness of a post (i.e., tweet) is related to the number of times the tweet has been retweeted. Different models have been proposed in the literature to understand the retweet proneness of a tweet (tendency or inclination of a tweet to be retweeted). In this paper, a further step is presented, thus several features extracted from Twitter data have been analyzed to create predictive models, with the aim of predicting the degree of retweeting of tweets (i.e., the number of retweets a given tweet may get). The main goal is to obtain indications about the probable number of retweets a tweet may obtain from the social network. In the paper, the usage of the classification trees with recursive partitioning procedure for prediction has been proposed and the obtained results have been compared, in terms of accuracy and processing time, with respect to other methods. The Twitter data employed for the proposed study have been collected by using the Twitter Vigilance study and research platform of DISIT Lab in the last 18 months. The work has been developed in the context of smart city projects of the European Commission RESOLUTE H2020, in which the capacity of communicating information is fundamental for advertising, promoting alerts of civil protection, etc.