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Abstract: Chitin, abundant in shrimp and crab shells, can be hydrolyzed to produce glucosamine, a compound widely used in medicine, agriculture, and material science. Efficient production of chitin monomers and their derivatives on a large scale can enhance the utilization of marine resources and reduce environmental pressure. However, current hydrolysis methods face technological and cost-related challenges, limiting them to experimental or small-scale production. This study explores the hydrolysis of chitin using acids, salts, and activated-carbon-supported transition metals, focusing on optimizing reaction parameters for improved monomer yield. Among six acids tested, hydrochloric acid yielded the highest amount of N-acetyl-D-glucosamine (NAG), while sulfuric acid was most effective for glucosamine (GlcN) production. Palladium-carbon was the most efficient metal catalyst for NAG yield, while nickel powder catalyzed the highest GlcN production. It was observed that increasing chitin quantity, while keeping phosphoric acid constant, led to a decrease in NAG and GlcN yields. Temperature variations within the range of 100-120°C showed minimal impact on the hydrolysis results. Additionally, among three salt catalysts, ammonium formate and ammonium acetate were most effective for NAG and GlcN yields, respectively. These methods offer potential for preparing chitin monomers or their derivatives while reducing energy consumption and simplifying hydrolysis conditions.Abstract: Chitin, abundant in shrimp and crab shells, can be hydrolyzed to produce glucosamine, a compound widely used in medicine, agriculture, and material science. Efficient production of chitin monomers and their derivatives on a large scale can enhance the utilization of marine resources and reduce environmental pressure. However, current hydrolysis met...Learn More
Abstract: In the process of lifting heavy objects with cranes, the shortcomings of current conventional detection methods were analyzed in terms of applicability, safety, and reliability. In response to the safety risks associated with the braking process and motion posture characteristics of crane lifting equipment, this paper proposes a method for detecting the braking process and motion posture of crane lifting equipment. By collecting data on the braking process and motion posture, and using Kalman filtering method for filtering and fusion, accurate data can be obtained; Analyze the waveform characteristics of experimental data and integrate them in the time domain to calculate the value of brake sliding displacement has improved the accuracy and efficiency of detection results and reduced detection costs. These analysis features and calculation results provide strong support for the comprehensive evaluation of the braking performance of cranes, which helps to promote the standardization of operation and improve overall operational safety, and ensure the safe use of lifting machinery and equipment.Abstract: In the process of lifting heavy objects with cranes, the shortcomings of current conventional detection methods were analyzed in terms of applicability, safety, and reliability. In response to the safety risks associated with the braking process and motion posture characteristics of crane lifting equipment, this paper proposes a method for detectin...Learn More
Abstract: To develop the system construction of civil aviation digital analysis technology, and totally understand the charactersitics of signal synthesis of antenna as well as antenna signal in the external field. Firstly, according to the field antenna radiation system of typical ATC navigation equipment, the digital model is established and the virtual space signal has been analysised systematically. Secondly, optimized antenna radiation characteristics parameters, signal quality verification and development innovation by antenna directivity design, which is one of the methods to change the radiation field pattern of antenna array. The digital model of research mainly includes establishment of a series of localozer antenna array system database, reesarch of signal coverage characteristic, spatial modulation analysis, performance verification of anti-interference and data analysis methods. According to the radiation performance of the radiated antennas models, a kind of optimized antenna array is simulated by design inspiraiton of the high gain antenna. The analysis result shows that the new designed antenna system has good coverage characteristics and stronger anti-interference ability, at the same time, this makes up for the wide aperture defects of the current widely used antenna array after industrialization. This design idea also can be applied to other kinds of communicaiton antennas, providing an effective method for improving spatial siganl.Abstract: To develop the system construction of civil aviation digital analysis technology, and totally understand the charactersitics of signal synthesis of antenna as well as antenna signal in the external field. Firstly, according to the field antenna radiation system of typical ATC navigation equipment, the digital model is established and the virtual sp...Learn More
