Dual-core System Research Articles

Comparative seismic fragility assessment of mid-rise steel buildings with non-buckling (BRB and SMA) braced frames and self-centering energy-absorbing dual rocking core system

During the past two decades, many emerging smart lateral force-resisting systems have been proposed for achieving better post-earthquake recoverability than the conventional ones in steel buildings. The Self-centering Energy-absorbing Dual Rocking Core (SEDRC) system has been developed recently by the authors for achieving excellent self-centering behavior with large deformability in steel buildings. This paper intends to investigate the benefit of steel buildings using the SEDRC system compared to that using other emerging smart lateral force-resisting system (e.g., shape memory alloy braced frame (SMABF)) and conventional one (e.g., buckling restrained braced frame (BRBF)). For this purpose, first, three six-story steel buildings with BRBFs, SMABFs, and SEDRC systems, were designed to obtain similar inter-story drifts subjected to the design basis earthquakes. Second, nonlinear static and dynamic analyses were conducted to preliminarily study the seismic performance of the designed buildings. Then, incremental dynamic analyses (IDAs) with far-field and near-fault ground motion inputs were conducted to study the seismic responses of the designed buildings under different seismic hazard levels. Finally, the results from the IDAs were analyzed in a probability framework. The inter-story drifts, residual inter-story drifts, and floor acceleration responses of the considered systems were analyzed to investigate the seismic fragility of the structural and nonstructural components in the designed buildings. The analysis results indicate that the SEDRC system can achieve the best structural collapse-resistant capacity under both far-field and near-fault ground motions because of the excellent deformability. The SMABF and SEDRC system show better seismic resilience performance by controlling the residual inter-story drift responses than BRBF. Moreover, the SEDRC system can obtain a smaller exceedance probability of damage states associated with nonstructural components depending on floor acceleration responses than SMABF because of uniform inter-story drift responses.

Hardware Implementation of Authenticated Ciphers for Embedded Systems

The demand for embedded systems in applications that handle critical or private information has strongly focused designers' attention on the security aspects of this kind of system. Using the C programs and HDL descriptions available in the repositories of the CAESAR Competition and the ATHENa Project, this work presents a design flow that eases the development and evaluation of different solutions for the hardware implementation of authenticated ciphers and their incorporation as accelerating peripherals in embedded systems for different application cases. Three ciphers, finalists in the different categories established in the contest, have been analyzed, although the described approaches can be applied to any of the proposals submitted to the CAESAR Competition. A Zybo-Z7 development board that incorporates a Zynq-7000 device from Xilinx, which combines programmable logic from the FPGAs of the 7-Series with a dual-core Cortex-A9 ARM processing system, has been used as hardware platform in all the designs. The Vivado environment has been employed to perform the different stages of synthesis and verification necessary to carry out the implementation of the cipher, its conversion into an IP module, and its integration in an embedded system using different interconnection schemes that allow establishing cost/performance tradeoffs for different applications.

Construction of hydraulic chuck reliability test platform by ARM DSP dual-core system

To improve the data acquisition speed and accuracy of hydraulic chuck reliability test, a dual-core data acquisition system with ARM and DSP is constructed in combination with their respective characteristics. Taking full advantage of DSP’s fast operation speed, arm is suitable for interface, control and display, so as to realize high-speed and high-precision data acquisition and real-time online data processing, as well as various real-time data acquisition and information exchange functions.

Stabilization of one-dimensional Townes solitons by spin-orbit coupling in a dual-core system

It was recently demonstrated that 2D Townes solitons (TSs) in two-component systems with cubic self-focusing, which are normally made unstable by the critical collapse, can be stabilized by linear spin-orbit coupling (SOC), in Bose-Einstein condensates and optics alike. We demonstrate that 1D TSs, realized as optical spatial solitons in a planar dual-core waveguide with dominant quintic self-focusing, may be stabilized by SOC-like terms emulated by obliquity of the coupling between cores of the waveguide. Thus, SOC offers a universal mechanism for the stabilization of (quasi-) TSs. A combination of systematic numerical considerations and analytical approximations identifies a vast stability area for skew-symmetric solitons in the system’s main (semi-infinite) and annex (finite) bandgaps. Tilted (”moving”) solitons are unstable, spontaneously evolving into robust breathers. For broad solitons, diffraction, represented by second derivatives in the system, may be neglected, leading to a simplified model with a finite bandgap. It is populated by skew-antisymmetric gap solitons, which are nearly stable close to the gap’s bottom.

Stability and collisions of quantum droplets in [formula omitted]-symmetric dual-core couplers

We study the effect of the interplay between parity-time (PT) symmetry and optical lattice (OL) potential on dynamics of quantum droplets (QDs) forming in a binary bosonic condensate trapped in a dual-core system. It is found that the stability of symmetric QDs in such non-Hermitian system depends critically on the competition of gain and loss γ, inter-core coupling κ, and OL potential. In the absence of OL potential, the PT-symmetric QDs are unstable against symmetry-breaking perturbations with the increase of the total condensate norm N, and they retrieve the stability at larger N, in the weakly-coupled regime. As expected, the stable region of the PT-symmetric QDs shrinks when γ increases, i.e., the PT symmetry is prone to break the stability of QDs. There is a critical value of κ beyond which the PT-symmetric QDs are entirely stable in the unbroken PT-symmetric phase. In the presence of OL potential, the PT-symmetric on-site QDs are still stable for relatively small and large values of N. Nevertheless, it is demonstrated that the OL potential can assist stabilization of PT-symmetric on-site QDs for some moderate values of N. On the other hand, it is worth noting that the relatively small PT-symmetric off-site QDs are unstable, and only the relatively large ones are stable. Furthermore, collisions between stable PT-symmetric QDs are considered too. It is revealed that the slowly moving PT-symmetric QDs tend to merge into breathers, while the fast-moving ones display quasi-elastic collision and suffer fragmentation for small and large values of N, respectively.

Hardware-Efficient VLSI Design for Cascade Support Vector Machine with On-Chip Training and Classification Capability

Local processing of machine learning algorithms like support vector machine (SVM) is preferred over the cloud for many real-time embedded applications. However, such embedded systems often have stringent energy constraints besides throughput and accuracy requirements. Hence, hardware-efficient design to compute SVM is critical to enable these applications. In this paper, a hardware-efficient SVM learning unit is proposed using reduced number of multiplications and approximate computing techniques. These design techniques helped the learning unit to achieve 46.97% and 35.72% reductions in area and power when compared with those of the design using full multipliers. The proposed SVM learning unit supports on-chip training and classification. Energy-efficient dual-core, quad-core and octa-core cascade SVM systems were developed using the proposed SVM learning unit to expedite the on-chip training process. The runtime and energy efficiency of the cascade SVM systems improved with an increase in the number of cores. Interestingly, an average speedup of 421x in training time and a remarkable energy reduction of 24,497x were observed for the octa-core cascade SVM system when compared with the software SVM solution running on Intel Core i5-5257U processor. Moreover, the proposed octa-core cascade SVM system showed 73.75% and 65.78% lower area and power, respectively, than those of state-of-the-art cascade SVM architecture.

Development and validation test of a novel Self-centering Energy-absorbing Dual Rocking Core (SEDRC) system for seismic resilience

This research focuses on the development and validation tests of a novel seismic force-resisting system named as the Self-centering Energy-absorbing Dual Rocking Core (SEDRC) system for improving seismic resilience in steel building frames. An innovative Shear Friction Spring Damper (SFSD) was developed to provide seismic energy dissipation capacity and self-centering characteristic to the SEDRC system. Two Rocking Cores (RCs), pinned to the ground, are introduced in the SEDRC system for obtaining uniform energy absorption and evenly uniform distribution of the inter-story drift. The components, working principle, and mechanical performance of the proposed SEDRC system are first described, where its notable perceived advantages compared to the existing rocking system are highlighted. A physical test on the hysteretic behavior of individual friction ring springs used in SFSDs is subsequently introduced. Then, the validation test of the SEDRC system is presented, where the key properties including the strength, stiffness, deformability, re-centering capability and energy-absorption capacity are discussed in detail. The experimental test results of the SEDRC specimen show positive and stable flag-shaped hysteretic behavior. Nearly no residual drift was observed after removing the applied lateral forces up to 6% roof drift, indicating that the SEDRC system has excellent deformability and self-centering capability. The two RCs could remain elastic during the entire cyclic loading process and promote uniform distribution of inter-story drift in the SEDRC specimen. Moreover, the computational model of the SEDRC specimen was developed and verified. Twenty-one ground motions were utilized to investigate the dynamic behavior of the SEDRC system. Numerical results further confirm the expected seismic behavior of the SEDRC system.

Soliton-soliton dynamics in a dual-core system with separated nonlinearity and nonuniform Bragg grating

The interactions between stable quiescent Bragg grating solitons are investigated systematically in a dual-core system where one core is uniform and has Kerr nonlinearity and other is linear and is equipped with a Bragg grating with dispersive reflectivity. In a previous work, it has been shown that the model supports stable quiescent Bragg solitons which may contain sidelobes in their profile in case of strong dispersive reflectivity. The interactions of in-phase solitons may lead to a variety of outcomes in the absence of sidelobes including merger into a quiescent soliton, destruction of both solitons, symmetric or asymmetric separation of solitons and generation of three solitons. In case of $$\pi $$ -out-of-phase solitons without sidelobes, the solitons repel each other. However, in the presence of sidelobes, for both in-phase and $$\pi $$ -out-of-phase solitons, the interactions may result in the repulsion of solitons or the formation of a long-lasting bound state that eventually disintegrates into two separating solitons. We have identified the regions for different interaction outcomes in the plane of dispersive reflectivity and frequency.

Time-sensitivity-aware shared cache architecture for multi-core embedded systems

In embedded systems such as automotive systems, multi-core processors are expected to improve performance and reduce manufacturing cost by integrating multiple functions on a single chip. However, inter-core interference in shared last-level cache (LLC) results in increased and unpredictable execution times for time-sensitive tasks (TSTs), which have (soft) timing constraints, thereby increasing the deadline miss rates of such systems. In this paper, we propose a time-sensitivity-aware dead block-based shared LLC architecture to mitigate these problems. First, a time-sensitivity indication bit is added to each cache block, which allows the proposed LLC architecture to be aware of instructions/data belonging to TSTs. Second, portions of the LLC space are allocated to general tasks without interfering with TSTs by developing a time-sensitivity-aware dead block-based cache partitioning technique. Third, to reduce the deadline miss rate of TSTs further, we propose a task matching in shared caches and a cache partitioning scheme that considers the memory access characteristics and the time-sensitivity of tasks (TATS). The TATS is combined with our proposed dead block-based scheme. Our evaluation shows that the proposed schemes reduce deadline miss rates of TSTs compared to conventional shared caches. On a dual-core system, compared to a baseline, equal partitioning, and state-of-the-art quality-of-service-aware cache partitioning, our proposed dead block-based cache partitioning provides 9.3%, 30.5%, and 2.6% lower average deadline miss rates, respectively. On a quad-core system, compared to the baseline, equal partitioning, and state-of-the-art quality-of-service-aware cache partitioning, the combination of our proposed schemes provides 21.2%, 17.7%, and 4.1% lower average deadline miss rates, respectively.

Reuse-Distance-Aware Write-Intensity Prediction of Dataless Entries for Energy-Efficient Hybrid Caches

Emerging nonvolatile memory technologies act as a prominent choice for the larger on-chip caches on account of high density, good scalability, and low static power consumption. However, costly write operations reduce their possibility as a successor of SRAM. To mitigate this problem, a spin-transfer torque random-access memory (STT-RAM)-SRAM hybrid cache architecture is proposed. In such cache architectures, allocation of a write-intensive block is the key challenge for energy efficiency. This paper presents a data allocation policy that reduces the number of writes and energy consumption of the STT-RAM region in the last-level cache by considering the existence of private blocks. Dataless entries are allocated in STT region for such private blocks, and actual data is written only when the block is written back from L1. Heavily written blocks are subsequently migrated to SRAM region. We also present a predictor that helps to redirect the write backs from L1 of dataless entries directly to SRAM region, depending on the predicted reuse-distance-aware write intensity. Experimental evaluation shows that this technique reduces the energy consumption by 34.3% (19.6%) and 23.3% (14.1%), respectively, over two existing techniques in the case of dual (quad) core system.

Symmetry Breakings in Dual-Core Systems with Double-Spot Localization of Nonlinearity

We introduce a dual-core system with double symmetry, one between the cores, and one along each core, imposed by the spatial modulation of local nonlinearity in the form of two tightly localized spots, which may be approximated by a pair of ideal delta-functions. The analysis aims to investigate effects of spontaneous symmetry breaking in such systems. Stationary one-dimensional modes are constructed in an implicit analytical form. These solutions include symmetric ones, as well as modes with spontaneously broken inter-core and along-the-cores symmetries. Solutions featuring the simultaneous (double) breaking of both symmetries are produced too. In the model with the ideal delta-functions, all species of the asymmetric modes are found to be unstable. However, numerical consideration of a two-dimensional extension of the system, which includes symmetric cores with a nonzero transverse thickness, and the nonlinearity-localization spots of a small finite size, produces stable asymmetric modes of all the types, realizing the separate breaking of each symmetry, and states featuring simultaneous (double) breaking of both symmetries.

An Efficient Programming Skeleton for Clusters of Multi-Core Processors

This paper proposes a divide and conquer skeleton which aids parallel system programmers by (1) reducing programming complexity, (2) shortening programming time, and (3) enhancing code efficiency. To do this, the proposed skeleton exploits three mechanisms of (1) work-stealing, and (2) communication/computation overlapping, and (3) architectural awareness in the proposed divide and conquer skeleton. Using the work-stealing mechanism, when a processing element reaches a low-load condition, the processing core fetches a new job from the waiting queue of other cores. The second mechanism uses special threads to enable the proposed skeleton to overlapping computations with communications. The third mechanism considers the architectural parameters of the host system e.g., size of L1 cache, network bandwidth, network latency to maximally match a divide and conquer problem with the proposed skeleton. To evaluate the proposed skeleton, three benchmarks of merge sort, fast Fourier transform, and standard matrix multiplication are developed by the proposed skeleton as well as customized programming. Experiments are done in both simulation and real implementation environments. The set of six codes are simulated using COTSon simulator and also implemented on 28 dual-core real system. Obtained results from simulations showed an average of 12.6% speed-up of the proposed skeleton as compared to the customized programming; obtained speed-up in real environment is 9.6%. Furthermore, programming aided by the proposed skeleton, is at least 70% faster than custom programming while this difference increases as the program volume increases.

New blue emitting materials based on triple-core chromophores for organic light-emitting diodes

ABSTRACTA novel dual core system was recently developed for producing highly efficient organic emitters. Triple-core chromophores were prepared by extending a dual core chromophore. 1,6-Di-anthracen-9-yl-pyrene (1,6 DAP core), 6,12-di-anthracen-9-yl-chrysene (DAC core), and 2,7-di-anthracen-9-yl-pyrene (2,7 DAP core) were designed and synthesized. Its physical and electroluminescent properties were also investigated. Triple-core chromophores were used for the blue fluorescent emitters. A structure of the device was fabricated as ITO/2-TNATA (60 nm)/ NPB (15 nm)/synthesized materials (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). The device performance of 1,6 DAP core, DAC core, and 2,7 DAP core at 10 mA/cm2 corresponded to luminance efficiencies of 4.97 cd/A, 3.95 cd/A, and 3.50 cd/A, respectively.

Modeling of Wormhole Propagation in Carbonate Rocks by Use of In-Situ-Gelled Acids

Summary Diversion in heterogeneous carbonate reservoirs plays the most important role to the success of acidizing. Without the use of diversion, more acid preferentially flows into the high-permeability region and leaves the low-permeability region underreacted. But a clear understanding of diverting agents, such as polymer-based in-situ-gelled acids, can help uniformly stimulate the near-wellbore region. In this paper, we correct the rheological model that was developed by Ratnakar et al. (2013) according to experimental data from Gomaa and Nasr-El-Din (2010b) by considering shear-rate effect in a two-scale continuum model. It is found that the rheology parameters and shear rate are influential parameters in diversion. In addition, the amount of acid required for the breakthrough is found to be strongly dependent on rheology parameters and permeability in single-coreflood simulation. In our study, the viscosity of the spent acid is found to be the key parameter for diversion efficiency. We have constructed a mechanistic model similar to that in Panga et al. (2005) that simulates the acid injection in two dimensions. Then, we extended our simulation to dual-core systems with different permeability contrasts. The results show that there exists an intermediate injection rate that develops a wormhole in low-permeability core. This intermediate injection rate increases with increasing the permeability contrast. The results suggest that the dissolution pattern in the high-permeability core is dependent on the permeability contrast. It changes from wormhole to uniform shape when the permeability contrast increases.

Moving Bragg grating solitons in a semilinear dual-core system with dispersive reflectivity

The existence, stability and collision dynamics of moving Bragg grating solitons in a semilinear dual-core system where one core has the Kerr nonlinearity and is equipped with a Bragg grating with dispersive reflectivity, and the other core is linear are investigated. It is found that moving soliton solutions exist as a continuous family of solutions in the upper and lower gaps of the system’s linear spectrum. The stability of the moving solitons are investigated by means of systematic numerical stability analysis, and the effect and interplay of various parameters on soliton stability are analyzed. We have also systematically investigated the characteristics of collisions of counter-propagating solitons. In-phase collisions can lead to a variety of outcomes such as passage of solitons through each other with increased, reduced or unchanged velocities, asymmetric separation of solitons, merger of solitons into a quiescent one, formation of three solitons (one quiescent and two moving ones) and destruction of both solitons. The outcome regions of in-phase collisions are identified in the plane of dispersive reflectivity versus frequency. The effects of coupling coefficient, relative group velocity in the linear core, soliton velocity and dispersive reflectivity and the initial phase difference on the outcomes of collisions are studied.

A Structured Dual Split-Radix Algorithm for the Discrete Hartley Transform of Length $$2^{N}$$ 2 N

This paper presents a new split-radix algorithm for DHT of length \({N}=2^{n}\), called the Dual Split-Radix DHT (DSR DHT), that allows an efficient parallel implementation using a dual core system. Moreover, as it is different from existing split-radix algorithms for DHT, it offers an efficient hardware implementation similar to that for FFT. It avoids the so-called retrograde indexing specific to existing DHT algorithms that do not allow an efficient pipeline implementation.

A Way-Filtering-Based Dynamic Logical–Associative Cache Architecture for Low-Energy Consumption

Last-level caches (LLCs) help improve performance but suffer from energy overhead because of their large sizes. An effective solution to this problem is to selectively power down several cache ways, which, however, reduces cache associativity and performance and thus limits its effectiveness in reducing energy consumption. To overcome this limitation, we propose a new cache architecture that can logically increase cache associativity of way-powered-down LLCs. Our proposed scheme is designed to be dynamic in activating an appropriate number of cache ways in order to eliminate the need for static profiling to determine an energy-optimized cache configuration. The experimental results show that our proposed dynamic scheme reduces the energy consumption of LLCs by 34% and 40% on single- and dual-core systems, respectively, compared with the best performing conventional static cache configuration. The overall system energy consumption including CPU, L2 cache, and DRAM is reduced by 9.2% on quad-core systems.

Stability of Bragg grating solitons in a semilinear dual-core system with cubic–quintic nonlinearity

The existence and stability of quiescent Bragg grating solitons in a dual-core fiber, where one core contains a Bragg grating with cubic–quintic nonlinearity, and the other is a linear are studied. The model admits two disjoint bandgaps when the relative group velocity in the linear core, c, is zero: one in the upper half and the other in the lower half of the system’s linear spectrum. In the general case (i.e., $$c\ne 0$$ ), a central gap (which is a genuine gap) is formed, while the lower and upper gaps overlap with one branch of continuous spectrum, and therefore, they are not genuine bandgaps. For quiescent solitons, exact analytical solutions are found in implicit form for $$c=0$$ . For nonzero c, soliton solutions are obtained numerically. The system supports two disjoint families (referred to as Type 1 and Type 2) of zero-velocity soliton solutions, separated by a border. Both Type 1 and Type 2 soliton solutions exist throughout the upper and lower gaps but not in the central gap. The stability of both soliton families is investigated by means of systematic numerical simulations. It is found that Type 2 solitons are always unstable and are destroyed upon propagation. On the other hand, unstable Type 1 solitons may either decay into radiation or radiate some energy and evolve into a moving Type 1 soliton. Also, in the case of Type 1 solitons, we have identified stable regions in the plane of quintic nonlinearity and frequency. The influence of coupling coefficient and the relative group velocity in the linear core on the stability of solitons are analyzed.

Interaction dynamics of Bragg grating solitons in a semilinear dual-core system with dispersive reflectivity

The interactions of quiescent Bragg grating (BG) solitons in a semilinear dual-core system, where one core is nonlinear and is equipped with a BG with dispersive reflectivity and the other core is linear are investigated. It has been previously shown that the model supports stable quiescent solitons which may or may not have sidelobes in their profiles. The interaction of in-phase solitons can lead to various outcomes such as generation of two moving solitons with equal or unequal velocities, merger of solitons into a quiescent one, generation of three solitons (one quiescent and two moving ones) and destruction of solitons. The presence of sidelobes can radically change the interaction dynamics, e.g. in-phase solitons can repel or form a temporary bound state which subsequently splits into two separating solitons. We have identified the outcome regions for in-phase interactions through systematic numerical simulations in the plane of dispersive reflectivity vs. frequency. We have also analysed the effect of initial separation on the outcomes of interactions. It is found that when sidelobes are present in solitons’ profiles, the outcomes of the interactions are strongly dependent on the initial separation.

A PT -Symmetric Dual-Core System with the Sine-Gordon Nonlinearity and Derivative Coupling

As an extension of the class of nonlinear PT -symmetric models, we propose a system of sine-Gordon equations, with the PT symmetry represented by balanced gain and loss in them. The equations are coupled by sine-field terms and first-order derivatives. The sinusoidal coupling stems from local interaction between adjacent particles in coupled Frenkel–Kontorova (FK) chains, while the cross-derivative coupling, which was not considered before, is induced by three-particle interactions, provided that the particles in the parallel FK chains move in different directions. Nonlinear modes are then studied in this system. In particular, kink-kink (KK) and kink-anti-kink (KA) complexes are explored by means of analytical and numerical methods. It is predicted analytically and confirmed numerically that the complexes are unstable for one sign of the sinusoidal coupling and stable for another. Stability regions are delineated in the underlying parameter space. Unstable complexes split into free kinks and anti-kinks that may propagate or become quiescent, depending on whether they are subject to gain or loss, respectively.