Application of Big Data Technology in Audit

In the new era of rapid development of big data technology, the three key points of high-quality development of auditing are auditing talents, auditing rule of law and auditing technology. In the traditional audit process, auditors focus on professional judgment and professional competence, make audit plans, implement audit procedures and draw audit conclusions. However, there are many problems in traditional audit work, such as difficulty in obtaining sufficient external information and inefficiency in analyzing audit evidence. Therefore, auditors apply big data technology to audit work to solve various problems and put forward corresponding safeguard measures

Multiple positive solutions for boundary value problems of second-order differential equations system on the half-line

In this paper, we study the existence of positive solutions for boundary value problems of second-order differential equations system with integral boundary condition on the half-line. By using a three functionals fixed point theorem in a cone and a fixed point theorem in a cone due to Avery-Peterson, we show the existence of at least two and three monotone increasing positive solutions with suitable growth conditions imposed on the nonlinear terms

Positive solutions of boundary value problems for systems of second-order differential equations with integral boundary condition on the half-line

In this paper, we study the existence of positive solutions of boundary value problems for systems of second-order differential equations with integral boundary condition on the half-line. By using the fixed-point theorem in cones, we show the existence of at least one positive solution with suitable growth conditions imposed on the nonlinear terms. Moreover, the associated integral kernels for the boundary value problems are given

Rheological Properties of Tailor-Made Metallocene and Ziegler-Natta Based Controlled Rheology Polypropylenes

Controlled rheology polypropylenes (CRPP) have been produced industrially by peroxide induced degradation in post-polymerization reactive extrusion (REX) operations. This has been well developed for commodity Ziegler-Natta based polypropylene (ZN-PP) resins, resulting in materials with controlled rheological properties with accompanying narrower molecular weight distribution (MWD). In this work, this methodology has been tested on both metallocene based polypropylenes (mPP), which have a narrow MWD initially, and ZN-PP resins at various peroxide concentrations. The differences in their degradation process as well as the properties of the resulting CRPPs were compared. A previously developed kinetic model was used to simulate the degradation process at various peroxide concentrations. Modelling results for a mPP and a ZN-PP with similar molecular weight indicated that the MWDs of both materials approached “most probable distribution” (PDI=2) as expected, due to the random nature of the scission reactions involved. However, unlike the ZN-PP resin for which the polydispersity was sharply decreased, the MWDs of CRPPs from mPP was almost unchanged with a PDI of about 2. This indicated that polypropylenes from the two types could be used to produce CRPPs with specified/targeted MW and MWD patterns and therefore special properties. Two groups of tailor-made CRPPs were produced using mPP and ZN-PP. One group had similar MW but different MWDs and another group had similar melt flow rate (MFR). In particular, the zero-shear viscosity and rheological polydispersity, which were obtained through oscillatory iv shear rheometry, were successfully applied to monitor the MW level and the MWD of the products. The two series of materials were also submitted to extrusion tests using a single screw extruder equipped with a capillary die. Based on the extrusion results, with respect to the CRPPs of similar MW, materials of broader MWD, thus stronger shear-thinning at high shear rate, resulted in slower increase of extrusion pressure with apparent shear rate. The shear rate of the onset of extrudate melt-fracture, which coincided with previous studies of polypropylenes extrusion, was higher for broader MWD material. With respect to the CRPPs with similar MFR, a metric commonly used for grade inspection in industry, their extrusion behaviours were nearly identical

Micropore evolution in additively manufactured aluminum alloys under heat treatment and inter-layer rolling

The application of wire + arc additively manufactured (WAAM) aluminum alloys has been restricted by the porosity defect, which is generally detrimental to the mechanical properties. Suppressing of micropores in the WAAM components has attracted considerable attention in recent years. Inter-layer rolling was introduced to eliminate micropores during the WAAM deposition of the Al–Cu6.3 and Al–Mg4.5 alloys. The distribution characteristics and individual morphology of micropores were revealed by the X-ray diffraction tomography. Key findings demonstrated that the number, volume, size, and roundness of micropores in rolled alloys decreased similarly with increasing loads, eventually achieving a density of over 99.9%. After the heat treatment, the homogeneous distribution of fine (around 5.3 μm) and spherical (0.70–0.74) micropores was realized in the 45 kN rolled alloys. All the evaluated indicators of micropores in the 45 kN rolled + heat treated alloys were superior to the post-deposition heat treated state. The evolution mechanisms include the reprecipitation of hydrogen pores, formation of vacant voids, and re-opening of unclosed pores. The hybrid technique of WAAM + rolling + heat treatment has great potential in promoting mechanical properties of WAAM alloys. The results will provide a theoretical guidance for the design of high-performance WAAM aluminum alloy components

Microstructure, defects, and mechanical properties of wire + arc additively manufactured AlCu4.3-Mg1.5 alloy

The wire with a composition of AlCu4.3%Mg1.5% was customized and used to deposit the WAAM alloy with the power source of cold metal transfer. The microstructure, defect, and mechanical properties of the as-deposited and heat-treated WAAM alloys were studied. Key findings demonstrated that the microstructure of the as-deposited alloy was characterized by a hierarchical distribution of dendrites, equiaxed grains, and a slight number of columnar grains. The volume fraction of the network-like scattered coarse particles of second phases θ + S reduced by 95% after the T6 heat treatment. With an average microhardness of 161.4 HV, the mean yield strength and ultimate tensile strength of the WAAM alloy increased by 116% and 66% achieving 399 MPa and 485 MPa in the horizontal direction after heat treatment. The precipitation of a high density of needle-shaped metastable S′ precipitates was responsible for the significantly enhanced mechanical properties. However, this WAAM alloy has exhibited an anisotropic tensile property. A considerable number of sharp-angled defects like linear and chain-like micropores, which generally depress the mechanical properties, were formed in the WAAM alloys

A Historical Sedimentary Record of Mercury in a Shallow Eutrophic Lake: Impacts of Human Activities and Climate Change

Mercury and its derivatives are hazardous environmental pollutants and could affect the aquatic ecosystems and human health by biomagnification. Lake sediments can provide important historical information regarding changes in pollution levels and thus trace anthropogenic or natural influences. This research investigates the 100-year history of mercury (Hg) deposition in sediments from Chao Lake, a shallow eutrophic lake in China. The results indicate that the Hg deposition history can be separated into three stages (pre-1960s, 1960s–1980s, and post-1980s) over the last 100 years. Before the 1960s, Hg concentrations in the sediment cores varied little and had no spatial difference. Since the 1960s, the concentration of Hg began to increase gradually, and showed a higher concentration of contamination in the western half of the lake region than in the eastern half of the lake region due to all kinds of centralized human-input sources. The influences of anthropogenic factors and hydrological change are revealed by analyzing correlations between Hg and heavy metals (Fe, Co, Cr, Cu, Mn, Pb, and Zn), stable carbon and nitrogen isotopes (δ13C and δ15N), nutrients, particle sizes, and meteorological factors. The results show that Hg pollution intensified after the 1960s, mainly due to hydrological change, rapid regional development and urbanization, and the proliferation of anthropogenic Hg sources. Furthermore, the temperature, wind speed, and evaporation are found to interactively influence the environmental behaviors and environmental fate of Hg

Scalable Scheduling for Industrial Time-Sensitive Networking: A Hyper-flow Graph Based Scheme

Industrial Time-Sensitive Networking (TSN) provides deterministic mechanisms for real-time and reliable flow transmission. Increasing attention has been paid to efficient scheduling for time-sensitive flows with stringent requirements such as ultra-low latency and jitter. In TSN, the fine-grained traffic shaping protocol, cyclic queuing and forwarding (CQF), eliminates uncertain delay and frame loss by cyclic traffic forwarding and queuing. However, it inevitably causes high scheduling complexity. Moreover, complexity is quite sensitive to flow attributes and network scale. The problem stems in part from the lack of an attribute mining mechanism in existing frame-based scheduling. For time-critical industrial networks with large-scale complex flows, a so-called hyper-flow graph based scheduling scheme is proposed to improve the scheduling scalability in terms of schedulability, scheduling efficiency and latency & jitter. The hyper-flow graph is built by aggregating similar flow sets as hyper-flow nodes and designing a hierarchical scheduling framework. The flow attribute-sensitive scheduling information is embedded into the condensed maximal cliques, and reverse maps them precisely to congestion flow portions for re-scheduling. Its parallel scheduling reduces network scale induced complexity. Further, this scheme is designed in its entirety as a comprehensive scheduling algorithm GH^2. It improves the three criteria of scalability along a Pareto front. Extensive simulation studies demonstrate its superiority. Notably, GH^2 is verified its scheduling stability with a runtime of less than 100 ms for 1000 flows and near 1/430 of the SOTA FITS method for 2000 flows