81 research outputs found
Exploring logic-in-memory architectures with skyrmion technology
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
A skyrmion content-addressable cell for skyrmion magnetic memories
No full textContent-addressable memories (CAMs) allow searching a pattern, processing in parallel all the data stored. Beyond-CMOS technologies can provide new opportunities to improve CAM memories implementations both at the device and architectural level. In this article, we propose a ternary content-addressable memory cell based on skyrmion technology. The proposed memory cell is based on skyrmion racetrack memory. The cell is able to signal if the bit contained in the cell in form of skyrmion corresponds to an electrical input, the target of the search operation. The proposed design, verified by means of micromagnetic simulations, has an area of 0.054 mu m(2) and can perform a search operation in 3.3 ns with an energy of 10.5 fJ. The operation performed is non-destructive and does not require conversion between the magnetic and the electronic domains. For this reason, the designed cell has the potential to be used as a basic block for non-volatile CAM memories. Here, we propose also a layout structure to implement a CAM memory employing the proposed cell. This structure allows to achieve memory density comparable to traditional racetrack memories and execute at the same time CAM operations
A Supervisory Control Strategy for Improving Energy Efficiency of Artificial Lighting Systems in Greenhouses
No full textArtificial lighting systems are used in commercial greenhouses to ensure year-round yields. Current Light Emitting Diode (LED) technologies improved the system efficiency. Nevertheless, having artificial lighting systems extended for hectares with power densities over 50W/m2 causes energy and power demand of greenhouses to be really significant. The present paper introduces an innovative supervisory and predictive control strategy to optimize the energy performance of the artificial lights of greenhouses. The controller has been implemented in a multi-span plastic greenhouse located in North Italy. The proposed control strategy has been tested on a greenhouse of 1 hectare with a lighting system with a nominal power density of 50 Wm−2 requiring an overall power supply of 1 MW for a period of 80 days. The results have been compared with the data coming from another greenhouse of 1 hectare in the same conditions implementing a state-of-the-art strategy for artificial lighting control. Results outlines that potential 19.4% cost savings are achievable. Moreover, the algorithm can be used to transform the greenhouse in a viable source of energy flexibility for grid reliability
Simulation and Modeling of Racetrack Memories With VCMA Synchronization
No full textThe control of the motion of magnetic domains is of crucial interest for the development of several spintronic applications, such as high-density racetrack memories and domain wall logic. In these devices, domain wall manipulation can be achieved via pulsed currents or applying external fields. However, real-world applications require accurate signal synchronization systems, keeping limited the power budget. Up to now, geometrical restrictions in the magnetic wire, known as notches, were used to confine domain walls at the expense of high resolution of the fabrication process. The solution based on the Voltage-Controlled Magnetic Anisotropy (VCMA) effect appears more promising--it is successful for controlling the skyrmion motion--avoids the need for strong depinning currents, simplifies the fabrication process, and gives more freedom in the control logic. The anisotropy variation induced by the VCMA can create barriers or wells that can be used to limit the movement of domain walls and obtain an effective synchronization. In this article, we propose a system-level evaluation of the effectiveness of the proposed VCMA synchronization method. Starting from a two-coordinates model, the motion of domain walls, the performance, and the efficiency of the approach are evaluated. We modeled the delay using SPICE. The VCMA showed clear advantages in the realization of the confinement structure at the system level with respect to the notch solution
The APUPA bell curve. Ranganathan’s visual pattern for knowledge organization
No full textAmong many clever innovations, the pioneer of faceted classifications, S.R. Ranganathan, introduced a structural model called APUPA (Alien-Penumbral-Umbral-Penumbral-Alien). This model can be visualized in the form of a bell curve. APUPA is commonly cited as an ideal shape resulting from the arrangement of works according to the principles of faceted classification, which should enable a reader browsing shelves to visually find "his book" as located in the middle of a sequence of related subjects on both its left and its right. However, we show how this is but one application of a more general model of thought recurring throughout Ranganathan’s works. Main classes order of Colon Classification (CC), and anteriorizing common isolates, are two more features where the bell curve model can be observed. We analyze the presence of this concept in Ranganathan’s work through excerpts from a variety of his published books. The concept is compared with models adopted in the work of other classificationists, and with various ideas available in scientific literature, including Bernoulli numbers and the mathematical theory of communication. It can be concluded that the bell curve pattern is yet another facet of the deep originality of Ranganathan’s complex and rich classificatory thought
3D design of a pNML random access memory
No full textAmong various emerging technologies, Nano Magnetic Logic (NML) is the one that may represent, in future, a replacement of CMOS for many reasons. In the last years, researchers have been conducting experiments to understand the properties and potentialities of this novel technology. NML can be used to build any kind of logic circuit and, because of its intrinsic magnetic nature, it is perfectly suitable to store data. However, the exploration of NML structures used as memories is very poor. In this paper, we propose the design of a 4×4 memory entirely based on perpendicular NML (pNML) technology. Magnets are placed onto two different overlapped layers to avoid routing congestion. The novelty introduced by this work is a distributed and modular memory cell that enables the design of highly regular memory structures optimized in terms of area occupation and write and read latency. The entire memory was also modeled in VHDL (VHSIC Hardware Description Language) and simulated to demonstrate its functional correctness
Bistable Propagation of Monostable Molecules in Molecular Field-Coupled Nanocomputing
No full textThe molecular Field-Coupling Nanocomputing (FCN) is considered as one of the most promising technologies which are intended to overcome the problems of CMOS scaling. The information is encoded in the charge distribution of molecules and propagated through intermolecular electrostatic interaction. In this work, we analyze the information propagation in monostable molecules. These molecules have been analyzed so far as isolated elements, describing the possibility of encoding the information in their dipole moment, yet it is not clear whether they allow the information propagation, or the information is lost after a few molecules. We define a parameter named “bistable coefficient” which directly links the size and the polarizability of the molecule, and the intermolecular distance to the propagation of the information. The bistable coefficient provides a metric for the characterization of the bistable propagation. We demonstrate in this work that the bistability of the molecule is not an essential requirement for achieving computation. Monostable molecules witch guarantee a minimum value of the bistable coefficient provides bistable propagation. We define a Safe-Operating Area which determines the constraints which monostable molecules must satisfy in order to provide bistable information propagation
Roma nella Historia Augusta
No full textThe Anonymous author of the Historia Augusta didn’t know about Rome. He was not a member of the urban senatorial aristocracy of late-antique Rome, but, maybe, someone born somewhere else in the empire during the age of Valentinian III. The analysis of the Praefatio of the Vita divi Aureliani and of the other passages by ‘Flavius Vopiscus’, one of the fictitious avatars of the Anonymous writer, testifies to his complete ignorance of obvious topographic features of the Urbs. On the contrary, the Anonymous was well aware of the new role which the Forum Traiani – nowadays known as Forum Ulpium – played in the culture of the fifth century as a memorial of the past greatness of Rome
Skyrmion Logic-In-Memory Architecture for Maximum/Minimum Search
No full textIn modern computing systems there is the need to utilize a large amount of data in maintaining high efficiency. Limited memory bandwidth, coupled with the performance gap between memory and logic, impacts heavily on algorithms performance, increasing the overall time and energy required for computation. A possible approach to overcome such limitations is Logic-In-Memory (LIM). In this paper, we propose a LIM architecture based on a non-volatile skyrmion-based recetrack memory. The architecture can be used as a memory or can perform advanced logic functions on the stored data, for example searching for the maximum/minimum number. The circuit has been designed and validated using physical simulations for the memory array together with digital design tools for the control logic. The results highlight the small area of the proposed architecture and its good energy efficiency compared with a reference CMOS implementation
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