Static Safety for an Actor Dedicated Process Calculus by Abstract Interpretation

The actor model eases the definition of concurrent programs with non uniform behaviors. Static analysis of such a model was previously done in a data-flow oriented way, with type systems. This approach was based on constraint set resolution and was not able to deal with precise properties for communications of behaviors. We present here a new approach, control-flow oriented, based on the abstract interpretation framework, able to deal with communication of behaviors. Within our new analyses, we are able to verify most of the previous properties we observed as well as new ones, principally based on occurrence counting

Fast and Accurate Power Estimation of FPGA DSP Components Based on High-level Switching Activity Models

When designing DSP circuits, it is important to predict their power consumption early in the design flow in order to reduce the repetition of time consuming design phases. High-level modelling is required for fast power estimation when a design is modified at the algorithm level. This paper presents a novel high-level analytical approach to estimate logic power consumption of arithmetic components implemented in FPGAs. In particular, models of adders and multipliers are presented in detail. The proposed methodology considers input signal correlation and glitching produced inside the component. It is based on an analytical computation of the switching activity in the component which takes into account the component architecture. The complete model can estimate the power consumption for any given clock frequency, signal statistics and operands’ word-lengths. Compared to other proposed power estimation methods, the number of circuit simulations needed for characterizing the power model of the component is highly reduced. The accuracy of the model is within 10% of low-level power estimates given by the tool XPower, and it achieves better overall performance

NPTX1 Regulates Neural Lineage Specification from Human Pluripotent Stem Cells

SummaryNeural induction is the first fundamental step in nervous system formation. During development, a tightly regulated niche modulates transient extracellular signals to influence neural lineage commitment. To date, however, the cascade of molecular events that sustain these signals in humans is not well understood. Here we show that NPTX1, a secreted protein, is rapidly upregulated during neural induction from human pluripotent stem cells (hPSCs). By manipulating its expression, we were able to reduce or initiate neural lineage commitment. A time-course transcriptome analysis and functional assays show that NPTX1 acts in part by binding the Nodal receptor cofactor TDGF1, reducing both Nodal and BMP signaling. Our findings identify one of the earliest genes expressed upon neural induction and provide insight into human neural lineage specification

AMR, stability and higher accuracy

Efforts to achieve better accuracy in numerical relativity have so far focused either on implementing second order accurate adaptive mesh refinement or on defining higher order accurate differences and update schemes. Here, we argue for the combination, that is a higher order accurate adaptive scheme. This combines the power that adaptive gridding techniques provide to resolve fine scales (in addition to a more efficient use of resources) together with the higher accuracy furnished by higher order schemes when the solution is adequately resolved. To define a convenient higher order adaptive mesh refinement scheme, we discuss a few different modifications of the standard, second order accurate approach of Berger and Oliger. Applying each of these methods to a simple model problem, we find these options have unstable modes. However, a novel approach to dealing with the grid boundaries introduced by the adaptivity appears stable and quite promising for the use of high order operators within an adaptive framework

Sustainable lightweight foamed concrete using hemp fibre for mechanical properties improvement

Fibres have long been used as an additive in the fabrication of building elements and materials. A combination of natural and synthetic fibres has shown promise in preliminary research and testing, with the added benefit of greatly improved strengths of the composites. Compared to traditional reinforcement bars, natural fibre reinforcement's ratio of fibre required is significantly lower, making it more beneficial in terms of energy and economic values. Recent research has focused on the feasibility of using both natural and synthetic fibres as reinforcement in concrete and other construction materials. Thus, the purpose of this research is to investigate the feasibility of using hemp fibre at various percentages (0%, 0.2%, 0.4%, 0.6%, and 0.8%) as an additive in lightweight foamed concrete to enhance mechanical properties. Three LFC densities namely 500, 900 and 1300 kg/m3 were fabricated and tested. Axial compressive strength, flexural strength, splitting tensile strength, and ultrasonic pulse velocity were the four mechanical parameters that were assessed. The findings demonstrated that adding 0.4-0.6% of HF to LFC produced the best results for ultrasonic pulse velocity, compressive strength, flexural strength, and splitting tensile strength. The HF is essential in assisting to stop the spread of cracks in the plastic state of the cement matrix after the load was applied

Studies on durability properties of natural fibre-reinforced green lightweight foamed concrete employing industrial hemp fibres

The utilization of natural fibres for the invention of building materials has increased significantly in recent years in the construction industry. Hemp fibre-reinforced concrete, according to research, can provide low-cost building materials for residential and low-rise buildings while achieving sustainable construction and meeting future environmental targets. The purpose of this research was to improve the durability of lightweight foamed concrete (LFC) reinforced with hemp fibre (HF). Six weight fractions of HF were considered specifically 0.0% (control), 0.1%, 0.2%, 0.3%, 0.4% and 0.5%. Besides, three densities of LFC which were 500, 900 and 1300 kg/m3 were cast and tested. The properties evaluated were drying shrinkage, water absorption, depth of carbonation and porosity. From the durability tests, it was observed that the optimal results for water absorption, depth of carbonation and porosity tests were attained with the addition of 0.5% HF into LFC mixes. For the drying shrinkage test, LFC with the weight fractions of 0.3% (500 kg/m3), 0.4% (900 kg/m3) and 0.5% (1300 kg/m3) reveal the optimal drying shrinkage. This research has provided a foundation for further research into HF-strengthening LFC. There is a huge potential to utilize HF in cement�based materials for durability and mechanical properties enhancement. The use of industrial HF might make it possible to reduce fine aggregate while still producing LFC of higher quality. The inclusion of agricultural fibres in LFC will also promote the expansion of farming operations, which will have rewarding economic benefits

Mixed formulation for an easy and robust numerical computation of sorptivity

Sorptivity is one of the most important parameters for the quantification of water infiltration into soils. proposed a specific formulation to derive sorptivity as a function of the soil water retention and hydraulic conductivity functions, as well as initial and final soil water contents. However, this formulation requires the integration of a function involving hydraulic diffusivity, which may be undefined or present numerical difficulties that cause numerical misestimations. In this study, we propose a mixed formulation that scales sorptivity and splits the integrals into two parts: the first term involves the scaled degree of saturation, while the second involves the scaled water pressure head. The new mixed formulation is shown to be robust and well-suited to any type of hydraulic function - even with infinite hydraulic diffusivity or positive air-entry water pressure heads - and any boundary condition, including infinite initial water pressure head, h→-∞. Lastly, we show the benefits of using the proposed formulation for modeling water into soil with analytical models that use sorptivity. Copyright