Radar Signal Intra-Pulse Modulation Recognition Based on Deep Residual Network

In view of low recognition rate of complex radar intra-pulse modulation signal type by traditional methods under low signal-to-noise ratio(SNR),the paper proposes an automatic recog-nition method of complex radar intra-pulse modulation signal type based on deep residual network.The basic principle of the recognition method is to obtain the transformation relationship between the time and frequency of complex radar intra-pulse modulation signal through short-time Fourier transform(STFT),and then design an appropriate deep residual network to extract the features of the time-frequency map and complete a variety of complex intra-pulse modulation signal type recognition.In addition,in order to improve the generalization ability of the proposed method,label smoothing and L2 regularization are introduced.The simulation results show that the proposed method has a recognition accuracy of more than 95%for complex radar intra-pulse modulation sig-nal types under low SNR(2 dB).

Synergistic promotion of particulate matter reduction and production performance via adjusting electrochemical reactions in the zinc electrolysis industry

Heavy particulate matter (PM) pollution and high energy consumption are the bottlenecks of hydrometallurgy, especially in the electrolysis process. Therefore, an urgent need is to explore PM reduction methods with production performance co-benefits. This study presents three PM reduction methods based on controlling operating parameters, i.e., lowering electrolyte temperature, H2SO4 concentration, and current density of the cathode. The optimized conditions were also investigated using the response surface methodology to balance the PM reduction effect and Zn production. The results showed that lowering electrolyte temperature is the most efficient, with an 89.0% reduction in the PM generation flux (GFPM). Reducing H2SO4 concentration led to the minimum side effects on the current efficiency of Zn deposition (CEZn) or power consumption (PC). With the premise of non-deteriorating CEZn and PC, GFPM can be reduced by 86.3% at the optimal condition (electrolyte temperature = 295 K, H2SO4 = 110 g/L, current density = 373 A/m^(2)). In addition, the reduction mechanism was elucidated by comprehensively analyzing bubble characteristics, electrochemical reactions, and surface tension. Results showed that lower electrolyte temperature inhibited the oxygen evolution reaction (OER) and compressed gas volume. Lower H2SO4 concentration inhibited the hydrogen evolution reaction (HER) and reduced electrolyte surface tension. Lower current density inhibited both OER and HER by decreasing the reaction current. The inhibited gas evolutions reduced the microbubbles’ number and size, thereby reducing GFPM. These results may provide energy-efficient PM reduction methods and theoretical hints of exploring cleaner PM reduction approaches for industrial electrolysis.

Direct generation of Zn metal using laser-induced ZnS to eradicate carbon emissions from electrolysis Zn production

In response to the goal of net-zero emissions proposed by Intergovernmental Panel on Climate Change, Chinese government has pledged that carbon emissions will peak by 2030, and achieve carbon neutrality by 2060. However, the high carbon energy structure of traditional industries has aggravated environmental problems, such as greenhouse effect and air pollution. The goal of carbon neutrality will be difficult to achieve without the development of disruptive theories and technologies. The electrolytic zinc industry requires high-temperature roasting at ~1000 ℃, generating large amounts of greenhouse gases and SO_(2). High concentrations of sulfuric acid (200 g/L) are subsequently used for electrolysis, and each ton of zinc produced generates 50 kg of anode slime with lead content of up to 16%, as well as 0.35 m3 of wastewater containing zinc and lead. To solve these problems, an optical metallurgy method is proposed in this study. The proposed method uses laser-induced photoreduction to decompose ZnS and reduce metal ions to metal. Results indicate that Zn0 and S8 can be detected on the surface of ZnS at a specific wavelength and laser fluence. The generation mechanism of Zn0 is such that laser induces an electronic transition that breaks ionic bond in ZnS, resulting in its decomposition and photoreduction to Zn0 under an inert argon gas atmosphere. This method does not reduce other metals in the mineral since it does not use high-temperature roasting, providing a new way of producing high-purity metal without greenhouse gas emissions and heavy metal pollution caused by traditional zinc electrolysis.

A new method to determine composition of sphalerite without secondary pollution based on CIELAB color space

Currently,most of the methods formineral materials analysis generate secondary pollution,which is detrimental to human health.For instance,traditionalmethods for sphalerite analysis in the zinc(Zn)smelting industry including chemical titration,atomic absorption spectrometry,and inductively coupled atomic emission spectroscopy.Colored indicators and toxic heavy metals are used in the analytical processes,causing severe pollution.For some methods,liquid is transformed into gaseous plasma,which is more dangerous to human health.Due to large quantities of sphalerite being used,secondary pollution cannot be ignored.This study proposes a green analysis method for the detection of sphalerite based on colorimetry,which does not generate secondary pollution.The results show that the strong substitution ability of iron(Fe)for Zn contributes to their inverse correlation in contents.The lattice parameters decrease with the increasing Fe content,resulting in a darker coloration.Here,key colorimetry parameters of L*,a*,and b*show clear linear correlations with the Zn and Fe contents.Compared with traditional approaches,this new method is environmental friendly with high sensitivity and accuracy.The relative error and relative standard deviation were less than 10%and 5%,respectively.This study provides a significant reference for nonpollution determination of other mineral materials.