Pushing the Limits of Machine Design: Automated CPU Design with AI

Design activity -- constructing an artifact description satisfying given goals and constraints -- distinguishes humanity from other animals and traditional machines, and endowing machines with design abilities at the human level or beyond has been a long-term pursuit. Though machines have already demonstrated their abilities in designing new materials, proteins, and computer programs with advanced artificial intelligence (AI) techniques, the search space for designing such objects is relatively small, and thus, "Can machines design like humans?" remains an open question. To explore the boundary of machine design, here we present a new AI approach to automatically design a central processing unit (CPU), the brain of a computer, and one of the world's most intricate devices humanity have ever designed. This approach generates the circuit logic, which is represented by a graph structure called Binary Speculation Diagram (BSD), of the CPU design from only external input-output observations instead of formal program code. During the generation of BSD, Monte Carlo-based expansion and the distance of Boolean functions are used to guarantee accuracy and efficiency, respectively. By efficiently exploring a search space of unprecedented size 10^{10^{540}}, which is the largest one of all machine-designed objects to our best knowledge, and thus pushing the limits of machine design, our approach generates an industrial-scale RISC-V CPU within only 5 hours. The taped-out CPU successfully runs the Linux operating system and performs comparably against the human-designed Intel 80486SX CPU. In addition to learning the world's first CPU only from input-output observations, which may reform the semiconductor industry by significantly reducing the design cycle, our approach even autonomously discovers human knowledge of the von Neumann architecture.Comment: 28 page

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Multifrequency Phase Difference of Arrival Range Measurement: Principle, Implementation, and Evaluation

Real-time location system (RLS) based on RFID is an effective indoor positioning system. The battery-free and low cost UHF passive tags can be attached on almost any objects, which are recognized as the best medium to achieve high precision ranging and positioning for large-scale objects. This paper proposes an indoor range measurement based on multifrequency phase difference of arrival (MF-PDoA) using UHF RFID passive tags and discusses the measurement principle, experiment implementation, and results evaluation in detail. After a theoretical overview of MF-PDoA range measurement principle, it introduces an experimental prototype under EPC C1G2 standard for range measurements. Both our prototype and a commercial off-the-shelf RFID reader have been used to verify the measurement method. We propose a Kalman filter and weighting method to process the measuring data. Experiment results indicate that, in a real environment, this method can effectively improve the ranging accuracy, which lays a foundation to extend the proposed measurement into two to three dimensions indoor object positioning

Quantitative Estimation of Pipeline Slope Disaster Risk in China

Abstract China’s economic development is closely related to oil and gas resources, and the country is investing heavily in pipeline construction. Slope geological hazards seriously affect the long-term safe operation of buried pipelines, usually causing pipeline leakage, property and environmental losses, and adverse social impacts. To ensure the safety of pipelines and reduce the probability of pipeline disasters, it is necessary to predict and quantitatively evaluate slope hazards. While there has been much research focus in recent years on the evaluation of pipeline slope disasters and the stress calculation of pipelines under hazards, existing methods only provide information on the occurrence probability of slope events, not whether a slope disaster will lead to pipeline damage. Taking the 2015 Xinzhan landslide in Guizhou Province, China, as an example, this study used discrete elements to simulate landslide events and determine the risk level and scope for pipeline damage, and then established a pipe-soil coupling model to quantitatively evaluate the impact of landslide hazards for pipelines in medium- and high-risk areas. The results provide a reference for future pipeline disaster prevention and control

Enhanced thermoelectric performance of Cu2Se realized by Ag2S doping

In this paper, Cu2Se samples doped with different concentrations of Ag2S were prepared by mechanical alloying and spark plasma sintering. Ag and S elements diffused during the preparation process and appeared aggregation in EDS mapping images. AgCuSe impurity phase can be observed in Cu2Se samples after Ag2S doping. Because of the enhanced scattering of the low- and mid-frequency phonons by AgCuSe nano inclusion, the total thermal conductivity of the Ag2S doped samples exhibits a significant decrease. Additionally, the diffusion and substitution of S can efficiently impede the formation of Cu vacancies. Ag ions can also fill the Cu vacancies, leading to the decreasing carrier concentration. Finally, the thermoelectric property is improved and the maximum ZT value ∼1.5 is achieved at 820 K in Cu2Se/ 2% Ag2S, which is about 1.5 times of the undoped Cu2Se sample

Identification and characterization of a curly-leaf locus CL1 encoding an IAA2 protein in Brassica napus

The leaf is the main organ for rapeseed photosynthesis, and its morphology influences photosynthetic efficiency and supports increased planting density and yield. However, the molecular regulatory mechanism of leaf morphology in Brassica napus is poorly understood, restricting progress in breeding for the trait. We describe a novel dominant mutation, curly leaf 1 (cl1), which confers uneven dorsal–ventral axis development, irregular cellular structure and influenced gravitropic response in the seedling stage. The CL1 locus was mapped to a 1.573-Mb interval on chromosome A05 using simple sequence repeat (SSR) markers, and co-segregated with the phenotype of plants in the curly F2 population. A substitution (P62S) was identified in the highly conserved degron motif (GWSPV) of the IAA2 protein in the cl1 mutant, and the P62S substitution impaired the interaction between IAA2 and TIR1 in the presence of auxin, influencing auxin signaling. The P62S substitution-induced curly leaf phenotype was verified by ectopic expression of BnaA05.iaa2 in Arabidopsis and B. napus. Our findings explain the function of IAA2 in rapeseed, providing a foundation for future investigation of auxin signaling and the mechanisms underlying leaf development in B. napus

Enhanced thermoelectric performance of In-doped and AgCuTe-alloyed SnTe through band engineering and endotaxial nanostructures

Endotaxial nanostructures can reduce lattice thermal conductivity through enhancing phonon scattering without affecting electrical transport, leading to a high thermoelectric performance. On the other hand, band engineering can enhance electrical transport by improving the Seebeck coefficient through valence band convergence and the resonance level. In this paper, the synergistic effect of band engineering and endotaxial nanostructures was implemented in SnTe thermoelectric materials by alloying with AgCuTe and doping with Indium. The positron annihilation lifetime spectra show that the vacancy concentration in SnTe was reduced after alloying with AgCuTe, which led to a decreasing hole concentration and improved carrier mobility. Additionally, the diffusion of Ag in the matrix during the preparation can facilitate valence band convergence. Therefore, the power factor of SnTe is greatly increased to 18 μW cm−1 K−2 at 800 K, which can be further increased to 21.4 μW cm−1 K−2 at 800 K after In doping due to resonance level formation. Meanwhile, Cu2Te endotaxial nanostructures also can be observed in the TEM image after SnTe alloying with AgCuTe. So, the lattice thermal conductivity significantly reduced to 0.93 W m−1 K −1 in In-doped and AgCuTe-alloyed SnTe. Finally, we obtain an enhanced ZT value of 1.14 in Sn1.02In0.01Te-1%AgCuTe at 800 K

Gold-Catalyzed Cycloisomerization/1,5‑H Migration/Diels–Alder Reaction Cascade: Synthesis of Complex Nitrogen-Containing Heterocycles

An unprecedented gold-catalyzed cycloisomerization/1,5-H migration/Diels–Alder reaction cascade has been developed that enables the rapid construction of complex nitrogen polycyclic compounds. This one-pot, three-step cascade reaction offers good yields of the products and is promoted by a single gold catalyst under very mild conditions