PICO-NPA: High-Level Synthesis of Nonprogrammable Hardware Accelerators

The PICO-NPA system automatically synthesizes nonprogrammable accelerators (NPAs) to be used as co-processors for functions expressed as loop nests in C. The NPAs it generates consist of a synchronous array of one or more customized processor datapaths, their controller, local memory, and interfaces. The user, or a design space exploration tool that is a part of the full PICO system, identifies within the application a loop nest to be implemented as an NPA, and indicates the performance required of the NPA by specifying the number of processors and the number of machine cycles that each processor uses per iteration of the inner loop. PICO-NPA emits synthesizable HDL that defines the accelerator at the register transfer level (RTL). The system also modifies the user's application software to make use of the generated accelerator.The main objective of PICO-NPA is to reduce design cost and time, without significantly reducing design quality. Design of an NPA and its support software typically requires one or two weeks using PICO-NPA, which is a many-fold improvement over the industry norm. In addition, PICO-NPA can readily generate a wide-range of implementations with scalable performance from a single specification. In experimental comparison of NPAs of equivalent throughput, PICO-NPA designs are slightly more costly than hand-designed accelerators.Logic synthesis and place-and-route have been performed successfully on PICO-NPA designs, which have achieved high clock rates.     

Correction to: An Enhanced Crow Search Inspired Feature Selection Technique for Intrusion Detection Based Wireless Network System

Wireless Personal Communications -     

3T‐FASDM: Linear discriminant analysis‐based three‐tier face anti‐spoofing detection model using support vector machine

In recent years, to solve the problem of face spoofing, momentous work has been done in this field, but still, there is a need for establishing counter measures to the biometric spoofing attacks. Although trained and evaluated on different databases, impressive results have been achieved in existing face anti‐spoofing techniques, but biometric authentication is a very significant problem as imposters are using lots of reconstructed samples or fake synthetic material or structure that can be used for various attack purposes. For the first time, to the best of our knowledge, this paper explains the security for face anti‐spoofing detection using linear discriminant analysis and validates the results by calculating HTER and accuracy on different databases (i.e., REPLAY ATTACK and CASIA). The proposed model, that is, three‐tier face anti‐spoofing detection model (3T‐FASDM), is used for the detection of the fake biometric user and works well for real‐time applications. The proposed methods tested on a set of state‐of‐the‐art anti‐spoofing features for the face mode gives a very low degree of complexity as 26 general image quality measures are applied to differentiate among legitimate and imposter samples. The outcomes obtained from publically available data show that this technique has improved performance and accuracy by analyzing the HTER and machine learning classifiers that are helpful to differentiate among real and fake traits.     

Visualizing Energy Transfer at Buried Interfaces in Layered Materials Using Picosecond X‐Rays

Understanding the fundamentals of nanoscale heat propagation is crucial for next‐generation electronics. For instance, weak van der Waals bonds of layered materials are known to limit their thermal boundary conductance (TBC), presenting a heat dissipation bottleneck. Here, a new nondestructive method is presented to probe heat transport in nanoscale crystalline materials using time‐resolved X‐ray measurements of photoinduced thermal strain. This technique directly monitors time‐dependent temperature changes in the crystal and the subsequent relaxation across buried interfaces by measuring changes in the c‐axis lattice spacing after optical excitation. Films of five different layered transition metal dichalcogenides MoX₂ [X = S, Se, and Te] and WX₂ [X = S and Se] as well as graphite and a W‐doped alloy of MoTe₂ are investigated. TBC values in the range 10–30 MW m^?2 K^?1 are found, on c‐plane sapphire substrates at room temperature. In conjunction with molecular dynamics simulations, it is shown that the high thermal resistances are a consequence of weak interfacial van der Waals bonding and low phonon irradiance. This work paves the way for an improved understanding of thermal bottlenecks in emerging 3D heterogeneously integrated technologies.     

State-space realizations for output feedback control of linear differential-algebraic-equation systems

This work addresses the derivation of state-space realizations for the output feedback control of linear, high-index differential-algebraic-equation systems that are not controllable at infinity and for which the control inputs appear explicitly in the underlying algebraic constraints. The constrained state space of such systems depends on the control inputs, and thus, a state-space realization cannot be derived independently of the controller design. Motivated by this, initially a dynamic output feedback compensator is designed that yields a modified system for which the algebraic constraints are independent of the new control inputs. For this feedback modified system, a state-space realization is then derived which can be used for output feedback controller synthesis.     

Use of MODIS NDVI to evaluate changing latitudinal gradients of rangeland phenology in Sudano-Sahelian West Africa

This study is concerned with the implications of changing latitudinal gradients in vegetative phenology (green-up, senescence, and length of growing season) for the management of long-distance seasonal movements of livestock herds in Sudano-Sahelian West Africa. For a study area covering much of the southern half of Mali, phenological parameters were estimated using a double-logistic function fitted to seasonal NDVI trajectories for 1 km² MODIS data over the period 2000-2010. Green-up dates, senescence dates and length of growing season were all found to more strongly vary by latitude (+ 9 days/degree, − 5 days/degree and − 14 days/degree, respectively) than across years (+ 0.42 days/year, + 0.86 days/year and + 0.44 days/year respectively). Interannual and spatial variability of these parameters are highest at lower latitudes within the study area. The slopes of the relationship of phenological parameters with latitude change across the latitudinal range studied. Breakpoint analysis of annual green-up versus latitude curves identifies a mean inflection point of 13° north latitude above which the positive slope declines significantly. This previously-undescribed pattern is consistent with recent work on monsoonal dynamics showing rainfall onset being associated with an abrupt shift in the location of the ITCZ (monsoon onset) at latitudes north of 13° north latitude. The effects of the observed variation in latitudinal gradients of phenological variables on the direction and timing of regional livestock movements are discussed.     

Unveiling Active Sites for the Hydrogen Evolution Reaction on Monolayer MoS2

Here, the hydrogen evolution reaction (HER) activities at the edge and basal‐plane sites of monolayer molybdenum disulfide (MoS₂) synthesized by chemical vapor deposition (CVD) are studied using a local probe method enabled by selected‐area lithography. Reaction windows are opened by e‐beam lithography at sites of interest on poly(methyl methacrylate) (PMMA)‐covered monolayer MoS₂ triangles. The HER properties of MoS₂ edge sites are obtained by subtraction of the activity of the basal‐plane sites from results containing both basal‐plane and edge sites. The catalytic performances in terms of turnover frequencies (TOFs) are calculated based on the estimated number of active sites on the selected areas. The TOFs follow a descending order of 3.8 ± 1.6, 1.6 ± 1.2, 0.008 ± 0.002, and 1.9 ± 0.8 × 10^?4 s^?1, found for 1T′‐, 2H‐MoS₂ edges, and 1T′‐, 2H‐MoS₂ basal planes, respectively. Edge sites of both 2H‐ and 1T′‐MoS₂ are proved to have comparable activities to platinum (≈1–10 s^?1). When fitted into the HER volcano plot, the MoS₂ active sites follow a trend distinct from conventional metals, implying a possible difference in the reaction mechanism between transition‐metal dichalcogenides (TMDs) and metal catalysts.     

Estimation of Uncertainty in the Calibration of Industrial Platinum Resistance Thermometers (IPRT) Using Monte Carlo Method

Monte Carlo method has been implemented for uncertainty estimation in IPRT calibration. The work is based on the Callendar van Dusen equation for 0–500 °C calibration range. Derivation of the mathematics model for running the simulation is also described. Results are compared with output from the traditional GUM method and we find close agreement between two methods.