Experimental investigation of high temperature thermal-vibration characteristics for composite wing structure of hypersonic flight vehicles

A thermal-vibration test system is established by combining the high-temperature transient heating simulation system and vibration test apparatus, and this system can carry out experimental research on the thermal modal of high-temperature-resistant composite wing structure of hypersonic flight vehicles under high temperature environment with 1100°C. The vibration signals of the composite wing structure in high-temperature environments are transmitted to non-high temperature field by using self-developed extension configurations and then the vibration signals are measured and identified by using ordinary acceleration sensors. Based on a time-frequency joint analysis technique, the experimental data is analyzed and processed to obtain the key vibration characteristic parameters of composite wing structure, such as the natural frequency and mode shapes, in a thermal-vibration coupled environment up to 1100°C. The experimental results provide an important basis for the dynamic performance analysis and safety design of composite wing structure under high-temperature thermal-vibration conditions

Solely economic mitigation strategy suggests upward revision of nationally determined contributions

The use of equity principles to review the nationally determined contributions (NDCs) is critical to facilitating more ambitious climate actions. However, disagreement over the equity principles persists. We instead treat emission reduction as a solely economic behavior motivated by avoiding future economic damage from climate change. Assuming no international cooperation, we provide a solely economic mitigation pathway to review national climate pledges until 2100. Using the value in 2030 to review the NDCs, we find that the NDCs of China, the USA, and the EU are 1.5, 1.4, and 0.9 respective GtCO2eq lower than their solely economic emission levels, whereas India commits 3.8 GtCO2eq more than its solely economic emission level. We also propose an equal-effort cooperation scenario toward 2°C where each country reduces emissions by 28% of their solely economic levels in 2030. Through exploration of the economic trade-offs, our results suggest that more ambitious NDCs are urgently needed

Gynostemma pentaphyllum for dyslipidemia: A systematic review of randomized controlled trials

Objective: To evaluate the lipid-lowering effect and safety of Gynostemma pentaphyllum (GP) used alone or as adjunctive therapy for dyslipidemia. Methods: Eight databases and three clinical trial registries were searched until January 2022. Randomized controlled trials (RCTs) assessing the effectiveness of GP for dyslipidemia were included. Trial quality was assessed using the Cochrane Risk of Bias Tool 2.0. Data were analyzed by RevMan 5.4 with effects estimated as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI). Results: Twenty-two RCTs involving 2,407 dyslipidemia participants were included. Regarding the risk of bias, 14 RCTs had some concerns, seven RCTs were high, and one trial was low. GP was comparable to n-3 fatty acids (RR 0.89, 95% CI 0.62–1.28) and red yeast rice (RR 0.33, 95% CI 0.1–1.12) on normalization of serum lipids. GP plus n-3 fatty acid was superior in normalization of triglycerides (TG) and total cholesterol (TC) than n-3 fatty acids (RR 1.34, 95% CI 1.01–1.77). GP was similar to lipid-lowering agents (statins, fibrates, and n-3 fatty acids) in regulating TG, TC, and high-density lipoprotein cholesterol (HDL-C). GP plus lipid-lowering agents were superior to lipid-lowering agents in TG (MD −0.65 mmol/L, 95% CI −1.03 to −0.28), LDL-C (MD −0.57 mmol/L, 95% CI −1.07 to −0.08), and HDL-C (MD 0.15 mmol/L, 95% CI 0.11–0.20). GP was inferior to red yeast rice in TC (MD 0.64 mmol/L, 95% CI 0.15–1.13), TG (MD 0.43 mmol/L, 95% CI 0.15–0.71), and HDL-C (MD −0.25 mmol/L, 95% CI −0.47 to −0.04). GP had fewer adverse events than lipid-lowering drugs. Conclusion: Very low certainty evidence showed that GP’s effects on TC, TG, and HDL-C were comparable to that of lipid-lowering agents. Low certainty evidence showed that red yeast rice was superior to GP in TC, TG, and HDL-C. Low to moderate certainty evidence showed that the effects of GP plus lipid-lowering agents were superior to that of lipid-lowering agents on TG, LDL-C, and HDL-C. GP use for more than 8 weeks appears safe

Unified Normalization for Accelerating and Stabilizing Transformers

Solid results from Transformers have made them prevailing architectures in various natural language and vision tasks. As a default component in Transformers, Layer Normalization (LN) normalizes activations within each token to boost the robustness. However, LN requires on-the-fly statistics calculation in inference as well as division and square root operations, leading to inefficiency on hardware. What is more, replacing LN with other hardware-efficient normalization schemes (e.g., Batch Normalization) results in inferior performance, even collapse in training. We find that this dilemma is caused by abnormal behaviors of activation statistics, including large fluctuations over iterations and extreme outliers across layers. To tackle these issues, we propose Unified Normalization (UN), which can speed up the inference by being fused with other linear operations and achieve comparable performance on par with LN. UN strives to boost performance by calibrating the activation and gradient statistics with a tailored fluctuation smoothing strategy. Meanwhile, an adaptive outlier filtration strategy is applied to avoid collapse in training whose effectiveness is theoretically proved and experimentally verified in this paper. We demonstrate that UN can be an efficient drop-in alternative to LN by conducting extensive experiments on language and vision tasks. Besides, we evaluate the efficiency of our method on GPU. Transformers equipped with UN enjoy about 31% inference speedup and nearly 18% memory reduction. Code will be released at https://github.com/hikvision-research/Unified-Normalization.Comment: ACM MM'2

Vertical migration from surface soils to groundwater and source appointment of polycyclic aromatic hydrocarbons in epikarst spring systems, southwest China

Understanding the transfer process of polycyclic aromatic hydrocarbons (PAHs) in the karst terrain is of great importance to their ecological risk assessments, however, the impact of the vertical transfer of the soil PAHs on the underground water is largely unknown in the karst system. Here, the vertical distribution and the seasonal variation of 16 PAHs in the soils and the water of 4 epikarst spring catchments in Southwest China were investigated. The total concentration of the PAHs ranged within 61-3285 ng g in the soils, and 341-4969 ng L in the spring water. The vertical distribution of the PAHs in soils varied with ring numbers and altitude of the catchment. PAHs concentrations were linearly related with the total organic carbon (TOC) at different depths in the catchments 563-783 m above the sea level (A.S.L.). However, no correlation with TOC was observed in the catchment of a high altitude (2090 m A.S.L.), because the large water flux led to the fast migration of the 2-3 rings PAHs in soils. The PAHs in soils and springs were mainly derived from the combustion of grass/wood/coal, closely related with the primary fossil fuels used in this area. This study demonstrate that the groundwater was heavily polluted by PAHs in the karst terrains of Southwest China, due to the vertical transfer of PAHs from the surface soils, and effective protection was urgently needed