When Dataflow Analysis Meets Large Language Models

Dataflow analysis is a powerful code analysis technique that reasons dependencies between program values, offering support for code optimization, program comprehension, and bug detection. Existing approaches require the successful compilation of the subject program and customizations for downstream applications. This paper introduces LLMDFA, an LLM-powered dataflow analysis framework that analyzes arbitrary code snippets without requiring a compilation infrastructure and automatically synthesizes downstream applications. Inspired by summary-based dataflow analysis, LLMDFA decomposes the problem into three sub-problems, which are effectively resolved by several essential strategies, including few-shot chain-of-thought prompting and tool synthesis. Our evaluation has shown that the design can mitigate the hallucination and improve the reasoning ability, obtaining high precision and recall in detecting dataflow-related bugs upon benchmark programs, outperforming state-of-the-art (classic) tools, including a very recent industrial analyzer.Comment: 15 pages, 16 figures, 5 table

The Influences of a Clay Lens on the Hyporheic Exchange in a Sand Dune

A laboratory flume simulating a riverbed sand dune containing a low-permeability clay lens was constructed to investigate its influence on the quality and quantity of hyporheic exchange. By varying the depths and spatial locations of the clay lens, 24 scenarios and one blank control experiment were created. Dye tracers were applied to visualize patterns of hyporheic exchange and the extent of the hyporheic zone, while NaCl tracers were used to calculate hyporheic fluxes. The results revealed that the clay lens reduces hyporheic exchange and that the reduction depends on its spatial location. In general, the effect was stronger when the lens was in the center of the sand dune. The effect weakened when the lens was moved near the boundary of the sand dune. A change in horizontal location had a stronger influence on the extent of the hyporheic zone compared with a change in depth. The size of the hyporheic zone changed with the depth and position of the clay lens. There was a maximum of hyporheic extent with the lens at a depth of 0.1 m caused by changes of water flow paths

A fuzzy-based decision-making model for improving the carrying capacity of ship locks

This paper develops a decision-making model to assist the improvement of the carrying capacity of ship locks by combing fuzzy logic, the analytic hierarchy process (AHP) method, and the technique for order preference by similarity to an ideal solution (TOPSIS). A three-level hierarchical structure is constructed to identify the key factors influencing the carrying capacity of ship locks from the aspects of ship locks, vessels, environment, and administration. On this basis, a series of targeted strategies have been put forward to improve the carrying capacity of ship locks, and the TOPSIS method is applied to rank these strategies in terms of their performance. A case study of the five-stage dual-track ship lock of the Three Gorges Dam in China has been conducted to demonstrate the feasibility and rationality of the proposed model, and correlation analysis is conducted to verify the identified influencing factors in order to eliminate potential bias which may be generated from using AHP. The results obtained from the proposed methods are consistent with the real-life situation to a certain extent, indicating that the proposed method can provide a useful reference for improving the carrying capacity of ship locks.Peer reviewe

Ground-penetrating radar study of beach-ridge deposits in Huangqihai Lake, North China: the imprint of washover processes

© 2016, Higher Education Press and Springer-Verlag Berlin Heidelberg. Determining the origin of beach ridges in lacustrine basins can often be problematic. The sedimentary processes responsible for formation of beach ridges on the north shore of Huangqihai Lake were investigated by using ground penetrating radar (GPR). A 400 MHz GPR antenna was used to achieve a high vertical resolution of 0.04–0.08 m. The radar stratigraphy was then determined using principles of seismic stratigraphy. The radar facies (RF) were determined by analyzing internal configuration and continuity of reflections, as well as reflection termination patterns. The identified RF fall into three groups (inclined, horizontal and irregular). The inclined group consists of RF that display inclined reflections. The horizontal group consists of RF that exhibit predominantly horizontal reflections. In the irregular group, the reflections are typically weak. RF with reflections with gently landward dips in the shore-normal profile are interpreted as washover sheet deposits. RF with steeply landward-dipping and imbricated reflections are interpreted as washover lobes. Washover sheets develop when overwash fails to enter a significant body of water and sedimentation takes place entirely on the relatively flattened topography. Washover lobe development occurs when overwash enters a region in which topography dips steeply landward, and sedimentation takes place on the surface of washover sheets or previous washover lobes. The beach-ridge deposits are interpreted as being formed entirely from vertically and laterally stacked washover sheets and washover lobes. They were formed by wave-dominated processes and secondary overwash processes supplemented by longshore currents

Ooid factories operating under hothouse conditions in the earliest Triassic of South China

The concept of “Carbonate Factory” was introduced to describe areas of carbonate production and accumulation. In this paper, the “Ooid Factories” is used to analyze extensive Griesbachian (Triassic) oolite deposits in South China that, along with microbialites and lime-mud deposits from different carbonate depositional environments. Late Permian tropical shallow-water skeletal factories (dominant by calcareous algae, sponge, and other associated organisms) collapsed in pace with the most severe mass extinction event, and were rapidly replaced by mud-mound factories (microbialite and lime-mud deposits) and subsequent ooid factories in shallow-water circumstances of Griesbachian. Meantime, temporal nutrient-rich and high-temperature conditions probably delayed re-establishment of tropical shallow-water skeletal factories. As an elementary unit of ooid factories, Lower Triassic oolites have diagnostic characteristics of ooid fabrics (alternatively dark- and light-colored laminae), size ranges (1–5 mm), and grain compositions (pure ooids, and only a few gastropod and bivalve fragments). Continuous aggradational and progradational oolite sequences caused extensive oolite accumulations that significantly contribute to the development of platform architecture with the collaboration of mud-mound factories (mainly line-mud deposits) in South China, through the evolution of low-angle or homoclinal ramps in the early Griesbachian to distally steepened ramps or flat-topped shelves in the late Griesbachian. Moreover, ooid factories also developed in Western Tethyan, Cimmerian, and Arabian carbonate platforms within low latitudes of the Tethyan Ocean during the Griesbachian. It is suggested that extreme hothouse climate with (seasonal) dry conditions in low latitudes significantly facilitated the extensive carbonate production of ooid factories at that time due to the strong linear relationship between surface seawater temperature and carbonate saturation state.This work was jointly supported by the National Natural Science Foundation of China (grant numbers 41502115 and 41872119), the National Science and Technology Major Project (grant number 2016ZX05004002-001), the Innovation Grant of Key Laboratory of Carbonate Reservoirs, CNPC (grant number RIPED-HZDZY-2018-JS-198), and the IAS Post-Doctoral Research Grants (Spring Session, 2017). R.V.B. thanks Gregory Webb (UQ) and Stephen Eggins (ANU) for helpful discussions, and developed aspects of this research while holding a Visiting Professorship at Université de Lausanne (supported by funds from the Fondation Herbette) and a Guest Professorship at the Centre for Modern Physics, Chongqing University

Petroleum geological conditions and exploration potential of the Permian Qixia Formation in the middle segment of Western Depression, Sichuan Basin

In recent years, great breakthroughs have been achieved for the exploration in the Permian Qixia Formation of the Shuangyushi structure in the north and the Pingluoba structure in the south of the Western Depression of the Sichuan Basin (Chuanxi Depression), while the exploration of the same formation in the middle segment of the Chuanxi Depression has not been carried out. In order to accelerate the ultra-deep marine natural gas exploration of the Qixia Formation, based on a large number of outcrops around the middle segment of the Chuanxi Depression, combined with seismic and drilling data and previous research results, this study systematically combed the oil and gas geological conditions of the Qixia Formation and comprehensively analyzed its exploration potential. Results show that the Qixia Formation in the study area has comparable sedimentary background as the north and south segments of the Chuanxi Depression, and is a platform margin sedimentary facies with superior reservoir conditions. Moreover, the Qixia Formation in the study area is connected with the hydrocarbon generation center of the Cambrian Qiongzhusi Formation by source faults. The tight limestone and shale of Permian and the gypsolyte of Triassic can be potential excellent cap rocks. Therefore, the source-reservoir-cap assemblage of the Qixia Formation in this area is preferential for large-scale hydrocarbon accumulation

Origin of structurally controlled hydrothermal dolomite in epigenetic karst system during shallow burial: An example from Middle Permian Maokou Formation, central Sichuan Basin, SW China

Based on the outcrops, drilling cores, thin sections observation and geochemical analysis, studies were done on the genesis of dolomite in the Middle Permian of central Sichuan Basin. Mosaic fine-crystalline dolomite and subhedral-euhedral siliceous fine-crystalline dolomite can be identified microscopically, which have different geochemical characteristics. Genetic analysis indicates insufficient mantle-derived fluids and marine-derived fluids entered karst system through basement faults, and then were mixed with previously-preserved crust-derived fluids in varied degrees during early Longtan period; in the relatively porous karst system, carbonate sands were dolomitized to subhedral-euhedral dolomites; insufficient mantle-derived hydrothermal fluids were mixed with previously-preserved crust-derived fluids, with coincidence reconstruction on the regions where there were preexisting karst systems but short of hydrothermal fluids, resulting in precursor limestone breccias and host rocks dolomitized to form anhedral mosaic dolomite; during late Longtan period, the overlying sediments sealed the epigenetic karst systems, and the insufficient deep mantle-derived fluids were mixed with previous fluids within the karst systems, with coincidence reconstruction on the relatively porous dolomites, while the tight anhedral mosaic fine-crystalline dolomites didn't change much, forming two types of dolomites with different petrological and geochemical characteristics. Thus, the formation of preferable dolomite reservoir is possibly related to inland facies-controlled epigenetic karst, and therefore the exploration of Maokou Formation in Middle Permian should pay more attention to the karst-related reservoirs. Key words: structurally controlled hydrothermal dolomite, dolomite reservoir, epigenetic karst, Permian Maokou Formation, Sichuan Basi

Tailoring Young's modulus by controlling Al bond length and strength using positive Li and negative Mg

For decades, it has been widely accepted that adding Mg to Al alloys decays Young's modulus of Al alloys. However, the fundamental mechanism for Young's modulus reduction is still pending. In this study, we experimentally produce the Al–Li alloys and Al–Li–Mg alloys using centrifugal casting and trace Young's modulus as a function of the evolution of their precipitation structures. Atomic-resolution high-angle-annular-dark-field (HAADF) imaging in scanning transmission electron microscopy (STEM) indicates that the precipitate sizes of Al–Li and Al–Li–Mg alloys are essentially the same in the early and late stages of aging. While atomic resolution HAADF suggests that although the lattice constants of δ′-Al3Li in Al–Li and Al–Li–Mg alloys (0.404 nm) are consistent in the early aging stage, it changes to 0.422 nm in the Al–Li–Mg alloy at the end of peak aging, showing a significant expansion to the same level as α-Al (0.421 nm). The nanoindentation results confirm that Young's modulus decreases strongly from 89.04 to 76.39 GPa for Al–Li–Mg alloys due to the lattice relaxation. Combining atomic-resolution HAADF and first-principles calculations, it has been found that Mg atoms diffuse into Al3(Li, Mg) crystals by replacing Li in the L12 δ′-Al3Li and thus doping the crystal. Further, it has been found that Mg atoms expand the spacing between Al–Al and Al–Li pairs thereby lowering the energy between Al–Al and Al–Li bonds, which in turn stretches their potential energy curves reducing Young's modulus

Fabrication of Chiral 3D Microstructure Using Tightly Focused Multiramp Helico-Conical Optical Beams

Beams with optical vortices are widely used in various fields, including optical communication, optical manipulation and trapping, and, especially in recent years, in the processing of nanoscale structures. However, circular vortex beams are difficult to use for the processing of chiral micro and nanostructures. This paper introduces a multiramp helical–conical beam that can produce a three-dimensional spiral light field in a tightly focused system. Using this spiral light beam and the two-photon direct writing technique, micro–nano structures with chiral characteristics in space can be directly written under a single exposure. The fabrication efficiency is more than 20 times higher than the conventional point-by-point writing strategy. The tightly focused properties of the light field were utilized to analyze the field-dependent properties of the micro–nano structure, such as the number of multiramp mixed screw-edge dislocations. Our results enrich the means of two-photon polymerization technology and provide a simple and stable way for the micromachining of chiral microstructures, which may have a wide range of applications in optical tweezers, optical communications, and metasurfaces