DTA-PUF: Dynamic Timing-aware Physical Unclonable Function for Resource-constrained Devices

In recent years, physical unclonable functions (PUFs) have gained a lot of attention as mechanisms for hardware-rooted device authentication. While the majority of the previously proposed PUFs derive entropy using dedicated circuitry, software PUFs achieve this from existing circuitry in a system. Such software-derived designs are highly desirable for low-power embedded systems as they require no hardware overhead. However, these software PUFs induce considerable processing overheads that hinder their adoption in resource-constrained devices. In this article, we propose DTA-PUF, a novel, software PUF design that exploits the instruction- and data-dependent dynamic timing behaviour of pipelined cores to provide a reliable challenge-response mechanism without requiring any extra hardware. DTA-PUF accepts sequences of instructions as an input challenge and produces an output response based on the manifested timing errors under specific over-clocked settings. To lower the required processing effort, we systematically select instruction sequences that maximise error-rate. The application to a post-layout pipelined floating-point unit, which is implemented in 45 nm process technology, demonstrates the effectiveness and practicability of our PUF design. Finally, DTA-PUF requires up to 50× fewer instructions than existing software processor PUF designs, limiting processing costs and resulting in up to 26% power savings.

Triaxially deformed freely precessing neutron stars: continuous electromagnetic and gravitational radiation

ABSTRACT The shape of a neutron star (NS) is closely linked to its internal structure and the equation of state of supranuclear matters. A rapidly rotating, asymmetric NS in the Milky Way undergoes free precession, making it a potential source for multimessenger observation. The free precession could manifest in (i) the spectra of continuous gravitational waves (GWs) in the kilohertz (kHz) band for ground-based GW detectors, and (ii) the timing behaviour and pulse-profile characteristics if the NS is monitored as a pulsar with radio and/or X-ray telescopes. We extend previous work and investigate in great detail the free precession of a triaxially deformed NS with analytical and numerical approaches. In particular, its associated continuous GWs and pulse signals are derived. Explicit examples are illustrated for the continuous GWs, as well as timing residuals in both time and frequency domains. These results are ready to be used for future multimessenger observation of triaxially deformed freely precessing NSs, in order to extract scientific implication as much as possible.

Timing stability of three black widow pulsars

ABSTRACT We study the timing stability of three black widow pulsars (BWPs), both in terms of their long-term spin evolution and their shorter term orbital stability. The erratic timing behaviour and radio eclipses of the first two BWP systems discovered (PSRs B1957+20 and J2051−0827) were assumed to be representative for this class of pulsars. With several new black widow systems added to this population in the last decade, there are now several systems known that do not show these typical orbital variations or radio eclipses. We present timing solutions using 7–8 yr of observations from four of the European Pulsar Timing Array telescopes for PSRs J0023+0923, J2214+3000, and J2234+0944, and confirm that two of these systems do not show any significant orbital variability over our observing time span, both in terms of secular or orbital parameters. The third pulsar PSR J0023+0923 shows orbital variability and we discuss the implications for the timing solution. Our results from the long-term timing of these pulsars provide several new or improved parameters compared to earlier works. We discuss our results regarding the stability of these pulsars, and the stability of the class of BWPs in general, in the context of the binary parameters, and discuss the potential of the Roche lobe filling factor of the companion star being an indicator for stability of these systems.

Performance Analysis of 1 bit HPSC Adder

In the technological evolution of integrated circuits, one of the important and considerable issues is the guesstimate of behavioural analysis of the simple circuits. The simplicity of the theory of logical effort is efficient in the evaluation of timing behaviour of the network with normal CMOS implementation. Howbeit this concept is inefficacious with the hybrid circuits as the circuit structure becomes intricate. At the same time, innumerable circuits with the hybrid arrangement which are good enough in various parameters when compared with standard CMOS have been proposed for various applications. Elite coordinated circuits frequently use adders to accomplish better speed to the detriment of intensity utilization or structure exertion. Hence it is particularly required to comprehend the working of full adders as they thus make an effect in the general gadget execution. The circuits developed by hybrid approach use perceptible logic styles to intensify the performance. Hence there is a great necessity to have an efficient timing behaviour method to determine the proper performance of hybrid adder circuits. This paper presents an efficient investigation that gives the designer a higher level of structure opportunity to focus on a wide scope of utilizations and foresee their exhibition. For the standard and exact selection and reducing of a hybrid adder cell two parameters are taken; one is gain and the other one is the selection factor. These can be quantifiable on the single test bench for the executives of vitality productivity. The predictive analysis is firmly established by implementing in Mentor Graphics for the chosen adder blocks

The γ-γ fast-timing technique and the EXILL&FATIMA campaign

At the Institut Laue-Langevin in Grenoble, germanium-gated γ-γ fast-timing lifetime measurements of nuclear excited states in neutron-rich nuclei have been performed within a prompt γ-ray spectroscopy experimental campaign. We report on results obtained from the cold-neutron induced fission of 235U. The excited secondary fission products were stopped almost instantaneously within the thick target and the γ rays emitted were collected triggerlessly using the EXILL&FATIMA mixed array of HPGe and LaBr3(Ce) detectors. Precise lifetimes could be determined by analysing the γ-γ time difference spectra using the generalized centroid difference method. This picosecondsensitive method provides many advantages and is briefly explained. Still, the major source of systematic errors is related to the contribution of time-correlated Compton background. The EXILL&FATIMA results are discussed with respect to the typical energy-dependent timing behaviour of the background. According to the time response of the background, appropriate methods and a time correction for the sub-nanosecond regime are proposed.

Evolution of temporal interaction: A comparative approach to social timing

Increasing empirical research shows a deep connection between timing processes and neural processing of social information. An integrative theoretical framework for prospective studies in humans was recently proposed, linking timing to sociality. A similar framework guiding research in non-human animals is desirable, ideally encompassing as many taxonomic groups and sensory modalities as possible in order to embrace the diversity of social and timing behaviour across species. Here we expand on a previous theoretical account, introducing this debate to animal behaviour. We suggest adopting an evolutionary perspective on social timing in animals: i.e. a comparative approach to probe the link between temporal and social behaviour across a broad range of animal species. This approach should advance our understanding of animal social timing that is, how social behaviour and timing are mutually affected, and possibly of its evolutionary history in our own lineage. We conclude by identifying outstanding questions and testable hypotheses in animal social timing.

Evolution of temporal interaction: A comparative approach to social timing

Increasing empirical research shows a deep connection between timing processes and neural processing of social information. An integrative theoretical framework for prospective studies in humans was recently proposed, linking timing to sociality. A similar framework guiding research in non-human animals is desirable, ideally encompassing as many taxonomic groups and sensory modalities as possible in order to embrace the diversity of social and timing behaviour across species. Here we expand on a previous theoretical account, introducing this debate to animal behaviour. We suggest adopting an evolutionary perspective on social timing in animals: i.e. a comparative approach to probe the link between temporal and social behaviour across a broad range of animal species. This approach should advance our understanding of animal social timing that is, how social behaviour and timing are mutually affected, and possibly of its evolutionary history in our own lineage. We conclude by identifying outstanding questions and testable hypotheses in animal social timing.