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Abstract Background Contact tracing has been essential to reducing spread of COVID-19. Singapore leveraged technology to assist with contact tracing efforts using a Bluetooth-based app and token platform called ‘TraceTogether’. Methods We reviewed the impact of this system during the country’s Delta and Omicron waves (24 August 2021 to 17 February 2022) to identify differences in number of close contacts and time savings between full automation using TraceTogether alone as compared to manual contact tracing supplemented by TraceTogether. Characteristics of digital contact tracing app or token users were reviewed. Thereafter, the number of close contacts identified by manual and digital contact tracing methods, and the number of confirmed COVID-19 cases among contacts were analysed. The difference in time taken for identification of close contacts was also determined. Findings Adoption rate for TraceTogether was high, with 93.3% of cases having a registered device. There was a 9.8 h (34.9%) reduction in time savings for close contacts to be informed using TraceTogether alone compared to manual contact tracing supplemented by TraceTogether. The proportion of close contacts automatically identified through TraceTogether alone and turned positive was 3.6%. For those identified through manual contact tracing supplemented by TraceTogether, this proportion was 12.5% and 6.2% for those served quarantine orders and health risk warnings respectively. Interpretation The high adoption rate of ‘TraceTogether’ suggest that digital solutions remain a promising option to improve contact tracing in future epidemics. This may have been through its concurrent use with vaccine differentiated public health measures and policies which engender public trust. There is future potential for utilising such technology in managing communicable diseases to achieve good public health outcomes.

Benefitting from the interlaced networking structure of carbon nanotubes (CNTs), the composites of CNTs/polydimethylsiloxane (PDMS) have found extensive applications in wearable electronics. While hierarchical multiscale simulation frameworks exist to optimize the structure parameters, their wide applications were hindered by the high computational cost. In this study, a machine learning model based on the artificial neural networks (ANN) embedded graph attention network, termed as AGAT, was proposed. The datasets collected from the micro-scale and the macro-scale simulations are utilized to train the model. The ANN layer within the model framework is trained to pass the information from micro-scale to macro-scale, while the whole model is aimed to predict the electro-mechanical behavior of the CNTs/PDMS composites. By comparing the AGAT model with the original multiscale simulation results, the data-driven strategy is shown to be promising with high accuracy, demonstrating the potential of the machine-learning-enabled approach for the structure optimization of CNT-based composites.

Ureteral stents are commonly used medical devices for the treatment of urinary system diseases. However, while providing benefits to patients, they often give rise to various issues, with stent encrustation being a major concern for clinical physicians. This phenomenon involves the formation of attached stones on the stent’s surface, leading to potential complications such as increased fragility and laxity of the ureter, difficulties in stent removal, and a higher risk of stent fracture. Therefore, this review starts from the pathological mechanisms of stone formation and discusses in detail the two major mechanisms of stent encrustation: the conditioning film and the biofilm pathway. It also examines multiple risk factors associated with ureteral stents and patients. Furthermore, the review updates the research progress on the structure, materials, and bio-coatings of ureteral stents in the prevention and treatment of stent encrustation. It presents new insights into the prevention and treatment of stent encrustation. This includes individualized and comprehensive clinical guidance, the use of novel materials, and early intervention based on physiological and pathological considerations. Ultimately, the study offers an encompassing overview of the advancements in research within this field and provides the latest insights into strategies for preventing and treating stent encrustation.

In order to explore the potential application of oxygenated fuels, polyoxymethylene dimethyl ethers (PODE), as an alternative fuel for marine diesel engines, the fuel combustion performance and gas emission characteristics of pure diesel oil, diesel-blended PODE, and pure PODE were tested on a marine diesel engine under different running conditions. The experimental results indicate that oxygen consumption can be reduced by diesel-blended PODE and pure PODE. The in-cylinder pressure and exothermic curve were consistent with the trend of diesel oil. Also, the ignition delay of diesel-blended PODE and pure PODE decreased, and the diffusion rate was accelerated, which helped to improve the combustion performance of diesel engines. Diesel blended PODE and pure PODE reduced the particulate matter (PM) emissions by up to 56.9% and 86.8%, respectively, and CO emissions by up to 51.1% and 56.3%, respectively. NOx emissions were gradually decreased with engine load. CO2 emissions were slightly increased, and the effective fuel consumption was increased up to 48% and 132%, respectively. It was shown that PODE could provide comparable power in a marine diesel engine and improve the fuel combustion and gas emission of the engine as a clean alternative fuel for marine diesel engines.

Objective To discuss the preoperative application of arginine for inducing autophagy to alleviate postoperative liver damage in patients undergoing liver resection. Methods Out of 90 hepatocellular carcinoma （HCC） patients treated with liver resection in Xuzhou Central Hospital from January 2019 to December 2020, there were 30 patients with normal liver resection （control group） and 60 patients with preoperative application of arginine （experiment group）. In experiment group, continuous intravenous arginine infusion was given for 1 week in 30 cases （experiment group 1）, and intravenous infusion every other day was given in other 30 cases （experiment group 2）. Postoperative liver function was monitored, and western blot was used to detect changes in autophagy-related protein and apoptotic-related protein expressions. Length of hospital stay was recorded and compared. Results The values of liver function indicators in experiment groups were significantly lower than those in control group, and they were lower in experiment group 2 than those in experiment group 1（P＜0.05＝. The expressions of autophagy proteins in normal liver tissues of experiment group were higher than those in control group （P＜0.05＝, and there were no significant differences in them between experiment group 2 and experiment group 1（P＞0.05）. In experiment group, the expression of apoptosis protein in normal liver tissues was lower than that in control group, and it in experiment group 2 was superior to that in experiment group 1. HE staining showed that there were different degrees of liver cells necrosis and fatty degeneration in control group and experiment group, however, HE staining scores in experiment group 2 were lower than those in experiment group 1 and control group （P＜0.05＝. Length of hospital stay was （16.1±3.8） d in experiment group 1, （15.3±3.1） d in experiment group 2 and （18.0±2.8） d in control group （F=5.428, P＜0.01＝. The hospitalization time in two experiment groups were significantly shorter than that in control group （P＜0.05＝. Conclusion Preoperative application of arginine can induce the expression of autophagy protein, which can alleviate the liver injury in patients with liver resection to a certain degree. Moreover, the interval use of arginine before surgery shows better protective effect for liver function.

In recent years, electricity consumption has been increasing, while the supply of electricity is relatively lagging, and power shortages often occur. Therefore, the management of organized power consumption is an urgent task for the current power industry. Based on the characteristics of power load, this paper constructs a decision-making management framework for orderly power consumption by considering four aspects: generation, grid side, demand side, and social benefit. Through the various types of flexible load resources aggregated within the virtual power plant, it participates in regulating its power, effectively reduces the peak-valley difference, and realizes refined, orderly power consumption management. Finally, based on the multi-objective optimization model, refined decision-making for orderly power consumption with the participation of virtual power plants is constructed and compared to traditional decision-making for orderly power consumption. The results show that compared with conventional decision-making, the peak-to-valley difference is reduced by 8.7789 WM, the economic benefit of the power enterprise is improved by 228,300 yuan, and customer satisfaction is enhanced by 0.1613, which verifies the effectiveness of the decision-making method of the sequential power consumption in this paper.

The search for sustainable energy solutions has become urgent against the current energy crisis and increasing environmental pollution. Biomass energy conversion and utilization technology, a clean and renewable energy source, constantly evolves, particularly in biomass power generation technology. This technology can effectively reduce greenhouse gas emissions and dependence on fossil fuels. Biomass conversion and utilization techniques include combustion, gasification, and biochemical methods that generate different energy forms, including heat, electricity, and fuel. Developing these technologies provides strong technical support for optimizing energy structures and protecting the environment. The article explores the application of biopower technology in intelligent energy management of electricity and improves its efficiency. The efficiency of biopower technology and its influencing factors were investigated using the Data Envelopment Analysis (DEA) model and Tobit regression analysis. A study was conducted on ten biopower energy companies. The energy management efficiency score of 1 was present in six of these companies, suggesting a relatively high operational efficiency level. Company C has a super-efficiency value of 2.654, indicating its outstanding energy management efficiency. Factors such as human resource input, total investment, and annual production costs significantly affect energy management efficiency. By optimizing resource allocation and improving management efficiency, biopower technology can be applied more effectively to intelligent energy management, thus promoting sustainable development.

The continuous advancement of wireless mobile communication necessitates an increase in the allocated frequency bands for each generation. Consequently, higher frequency photodiodes are required in analog radio-over-fiber (ARoF) fronthaul solutions. However, the limited available bandwidth in the wireless domain poses challenges to efficiently utilize the capacity of these photodiodes. To overcome this obstacle, this paper explores the utilization of a single-photodiode base station configuration to enable hybrid digital radio-over-fiber (DRoF) and ARoF transmission. Furthermore, it proposes a straightforward signal processing approach to effectively separate the distinct analog and digital radio-over-fiber signals. To evaluate the feasibility of the proposed signal processing method, software simulations were conducted. The initial findings indicate that the combination of a single-photodiode base station configuration and the suggested signal processing approach holds promise for hybrid digital and analog radio-over-fiber systems. It demonstrates the potential to minimize the number of required photodiodes, thus improving efficiency in the context of limited available bandwidth.

Remote sensing has become an important means and method of geographical research. Water conservation is one of the most critical functions of terrestrial ecosystems. Research on water conservation in these areas is essential for water resource utilization and ensuring food security. This study focuses on the Ningxia Hui Autonomous Region, utilizing the concept of the water balance method. By collecting, obtaining, and processing various data sources, including precipitation, evapotranspiration, and land use, the study quantitatively analyses changes in land use in the research area. Based on this analysis, the water conservation status in the region from 2000 to 2020 is assessed. The research findings reveal the following key points: (1) The spatial distribution of water conservation in the Ningxia Hui Autonomous Region is highly uneven, with a pattern of more water conservation in the north and less in the south. There are significant differences in water conservation functions among various administrative units. (2) From 2000 to 2020, in the southern region of the Ningxia Hui Autonomous Region, the water conservation quantity has consistently increased and expanded northward. In the northern region, the water conservation quantity initially increased and then decreased. There was no significant change in water conservation quantity in the eastern and western regions. From 2000 to 2010, the water conservation function of all prefecture-level cities in Ningxia Hui Autonomous Region was improved However, from 2010 to 2020, Guyuan City experienced a substantial increase in water conservation quantity, while other prefecture-level cities showed varying degrees of decrease.

The use of antibiotics to treat diarrhea and other diseases early in life can lead to intestinal disorders in infants, which can cause a range of immune-related diseases. Intestinal microbiota diversity is closely related to dietary intake, with many oligosaccharides impacting intestinal microorganism structures and communities. Thus, oligosaccharide type and quantity are important for intestinal microbiota construction. Galactooligosaccharides (GOS) are functional oligosaccharides that can be supplemented with infant formula. Currently, information on GOS and its impact on intestinal microbiota diversity and disorders is lacking. Similarly, GOS is rarely reported within the context of intestinal barrier function. In this study, 16S rRNA sequencing, gas chromatography, and immunohistochemistry were used to investigate the effects of GOS on the intestinal microbiota and barrier pathways in antibiotic-treated mouse models. The results found that GOS promoted Bifidobacterium and Akkermansia proliferation, increased short-chain fatty acid levels, increased tight junction protein expression (occludin and ZO-1), increased secretory immunoglobulin A (SIgA) and albumin levels, significantly downregulated NF-κB expression, and reduced lipopolysaccharide (LPS), interleukin-IL-1β (IL-1β), and IL-6 levels. Also, a high GOS dose in ampicillin-supplemented animals provided resistance to intestinal damage.

The emerging method of microwave (MW) heating was adopted to synthesize a phase pure La0.7Na0.3MnO3 from their oxide precursors. The MW power (P) used for heating the sample was varied from P = 1000 W to 1600 W to examine the effect of MW power on its physical properties. A well-crystalline single phase La0.7Na0.3MnO3 was achieved in 20 min of MW irradiation with P = 1600 W. The obtained grain sizes at P = 1000 W have grown bigger and densified while increasing the P = 1600 W. Growth in the grains was reflected in the resistivity of La0.7Na0.3MnO3 prepared at high P. As the P increases from 1000 W to 1600 W, the resistivity decreases drastically and the metal–insulator transition also becomes sharp at a temperature very close to TC whereas the ferromagnetic Curie temperature (TC) is least affected. The sample prepared at low P showed larger microwave absorption than the sample prepared under high P. These findings were correlated and discussed with the structural and morphological features acquired by microwave irradiation with different powers.

The effect of cooling rates on acicular ferrite (AF) nucleation was observed in situ by laser scanning confocal microscopy. The precipitation characteristics of TiN–MnS inclusions, the austenite grain size, and the content and morphologies of AF were analyzed and compared under different cooling rates. The results indicated that with the increase of the cooling rate, the size of TiN–MnS inclusions precipitated in the test steel gradually decreased while the inclusion number increased. When the cooling rate increased from 0.2 to 10°C·s−1, the average inclusion size decreased from 2.7 to 1.3 µm. The austenite grain size decreased gradually with the increase of the cooling rate, and the larger the cooling rate was, the more uniform the grain size distribution. The AF proportion increased first and then decreased, it reached the maximum when the cooling rate was 5°C·s−1, which accounted for 82.6%. Meanwhile, the dendrite size decreased gradually, the average length decreased from 30 to 5 µm, and the average width decreased from 2.8 to 0.7 µm when the cooling rate increased from 0.2 to 10°C·s−1.

The purpose of this study was to prepare a novel Angiotensin-I-Converting Enzyme(ACE) inhibitory peptide by hydrolyzing sheep casein with protease and analyze its molecular inhibitory mechanism, so as to provide technical support for the development of functional sheep milk polypeptide dairy products. In this experiment, sheep casein was used as raw material, with hydrolysis degree, ACE inhibition rate and molecular weight distribution as indexes, the most suitable protease was selected from four proteases, and the components with less than

Human resource management organisation's goal must be achieved by regulating employee behaviour through a restraint system. We conduct quantitative research on employee behaviour under organisational constraints, which is an essential means to ensure the organisation's healthy and stable development. The employees themselves adapt to the organisational goals, obey the organisation's constraint system and allocate their resources so that there is less research on optimising their behaviour. This article briefly reviews the research and application of economic theory, organisational behaviour, human resource management and other aspects of optimising employee resource allocation behaviour. The thesis defines organisational resources and divides them into three types. Based on the constraint system, we turn the organisation's control, requirements or incentives on employee behaviour into above or below employee operating constraints; we believe that the constraint system has the characteristics of discrete and hanging river effects, and we have obtained an evaluation. Two algorithms of the organisational constraint system. The article discusses employee resources and behaviours. At the same time, it attempts to construct a quantitative model based on the employee's multi-objective, nonlinear, continuous and discrete constraints, on the allocation of resources and behaviour optimisation and on the employee's adaptation to the organisational constraints. Under the premise of optimisation, several situations in which the model solves the optimal solution are studied. The research found that this article can fill the gaps in employees’ self-adaptation to organisational goals and behaviour optimisation quantitative models.

Objective(s): This study aimed to evaluate the effects and the underlying mechanisms of tertiary butylhydroquinone (TBHQ) on diabetic liver steatosis and cell survival. Materials and Methods: We performed streptozocin injection and used a high-sugar-high-fat diet for mice to develop an animal model of type 2 diabetes mellitus (T2DM). Bodyweight, blood glucose levels, and content of insulin were measured on all of the mice. The liver tissues were observed by hematoxylin-eosin staining. Protein levels of the liver were measured by Western blot analysis in mice. Primary hepatocytes were induced by hypochlorous acid (HClO) and insulin to form insulin resistance (IR). Primary hepatocyte apoptosis was observed by Hoechst staining. The PI3K/AKT signaling pathway and β-arrestin-2 factor were evaluated by Western blot assay. Results: TBHQ reduced the blood glucose level and content of insulin in serum, increased body weight, and effectively alleviated liver steatosis in diabetic mice. TBHQ significantly up-regulated the expression of p-PI3K, p-AKT, GLUT4, GSK3β, and β-arrestin-2 in the liver of diabetic mice. Cell experiments confirmed that TBHQ increased the survival ability of primary hepatocytes, and TBHQ improved the expression of p-PI3K, p-AKT, GLUT4, and GSK3β by activating β-arrestin-2 in primary hepatocytes. Conclusion: TBHQ could alleviate liver steatosis and increase cell survival, and the mechanism is due in part to β-arrestin-2 activation.

A prediction model based on Deep Belief Network（ DBN） was proposed to accurately predict the cutting load of the shearer’s spiral drum. The DBN model uses 7 characteristic parameters which include 2 guiding boots,2 smooth boots,rocker arm vibration,idler shaft,and cutting motor current as visual input. By means of unsupervised level greedy learning,the higher level features are represented,the intelligence of the identification process is enhanced,and the complexity and imprecision of artificial features extraction are avoided. The test results show that the proposed method is suitable for predicting the load of the spiral drum of coal miner,which has strong characteristic extraction ability and better performance than BP neural network.

Compared with the orbital angular momentum (OAM) wave whose 3D radiation pattern is a central-hollowed cone, the plane spiral orbital angular momentum (PSOAM) wave propagates along the transverse direction, which is far more convenient for practical applications. In this paper, traditional microstrip Yagi antennas are formed into a uniform circular array (UCA) to radiate PSOAM electromagnetic waves, which has the outstanding advantage of a flat structure. Firstly, the fundamentals of generating PSOAM by microstrip Yagi antenna array is introduced. Secondly, a circular microstrip Yagi PSOAM antenna array fed by a self-designed Wilkinson feeding network is designed, fabricated and measured. Eight microstrip Yagi antenna elements and its feeding network are printed on the upper and lower substrate, respectively. The profile of the proposed antenna is only $0.16\lambda _{0} $ , lower than other PSOAM antennas, which is convenient for integration with wireless communication systems. Both simulation and measurement results depict that it is capable of generating PSOAM with mode number $l=3$ on 3.43GHz. From 3.15GHZ to 3.65GHZ, the vortex electromagnetic wave of $l=3$ can be observed. The proposed microstrip Yagi antenna based on UCA provides a new way for the research of practical PSOAM antennas, has broad prospect in the future of the reconfigurable field.

Single-nucleotide polymorphisms (SNPs) are the abundant forms of genetic variations, which are closely associated with serious genetic and inherited diseases, even cancers. Here, a novel SNP detection assay has been developed for single-nucleotide discrimination by nanopore sensing platform with DNA probed Au nanoparticles as transport carriers. The SNP of p53 gene mutation in gastric cancer has been successfully detected in the femtomolar concentration by nanopore sensing. The robust biosensing strategy offers a way for solid nanopore sensors integrated with varied nanoparticles to achieve single-nucleotide distinction with high sensitivity and spatial resolution, which promises tremendous potential applications of nanopore sensing for early diagnosis and disease prevention in the near future.

Epidermal inclusion cysts (EICs) of the breast develop in the deep breast parenchyma, and they are very rare. Only about 10 cases have been reported in the English-language literature to date. In this report, we present a rare case of a giant EIC with infection arising within the deep breast parenchyma. Unlike a typical EIC of the breast, the EIC in the present case was a cystic and solid lesion containing a large amount of liquid within the cyst and popcorn-like calcification in the wall. In this report, we describe the contrast-enhanced spectral mammography (CESM), ultrasonography, and computed tomography findings and provide a reference for the diagnosis of EICs. To the best of our knowledge, this is the first report of the CESM findings of an EIC. Our case illustrates that CESM has excellent performance similar to that of magnetic resonance imaging and is much more effective than conventional digital mammography. Additionally, our case indicates that precise correlation of CESM with ultrasonography findings contributes to the diagnosis of EICs. This rare case with multiple imaging findings will increase the awareness of EICs in the breast parenchyma.

Covalent organic frameworks (COFs) are a class of porous organic crystal materials. Since Yaghi and co-workers reported the first COF material in 2005 (Côté, A. P.; Benin, A. I.; Ockwig, N. W.; O’Keeffe, M.; Matzger, A. J.; Yaghi, O. M. Science2005, 310, 1166–1170), COFs have shown great potential and research value in many fields, for instance, gas storage and separation, photoelectric function, fluorescence sensor, catalysis, drug delivery, dye and pollutant adsorption, electronic devices and so on. In this review, the frequently used analysis and characterization methods for COFs are summarized, and two to three examples are selected for each analysis and characterization technique in order to explain it in detail. The selected examples of COFs, which either had a unique structure and feature, or were reported for the first time, can be conducive to understanding COFs and their analysis methods better and faster. The application of COFs in analysis and detection is also introduced in this review, including fluorescent analysis, separation and enrichment. The cooperation between analytical chemistry and COFs is fully reflected. This review is helpful for the person interested in this subject and provides some useful information on the characterization methods and the applications of COFs for the beginners.

In view of the problems that influence of viscoelasticity of conveyor belt on starting process is neglected in current research on driving and control of belt conveyor, and belt conveyor starting process cannot be simulated well, mechanical properties and viscoelastic model of the conveyor belt were analyzed and Voigt model was selected for modeling of conveyor belt. Simulink and AMESim co-simulation platform was used to establish model of the mechanical part and motor control part of the belt conveyor separately. Three-point driving and control system of long distance belt conveyor was designed according to principle of direct torque control and the idea of cooperative control. The system adopts master-slave control strategy, takes head driving motor as main driver and the rest as slave drivers to control output speed and torque of the three drivers at the head part, middle part and tail part of the belt conveyor, which enables the belt conveyor to start and run smoothly with the preset speed curve. The simulation results show that although load torque of the conveyor is constantly changing due to viscoelastic effect of conveyor belt and the change of acceleration of the conveyor, the three drivers at the head part, middle part and tail part of the belt conveyor can track the preset starting speed well, which indicates that the three-point driving and control system can control the start-up and operation of the belt conveyor well.

In order to make accurate diagnosis for the scraper conveyor speed reducer failure study. This paper proposes a improved firefly algorithm to optimize neural network based fault diagnosis method. Firstly, the characteristics of the fault characteristic parameters of the blade conveyor are extracted. The second application feature data sample for fault diagnosis model based on neural network training. Using the improved firefly algorithm to optimize neural network weights and threshold, to speed up the optimum value of, get the optimal model of the network. Preliminary studies suggest that the improved firefly algorithm combined with BP（back propagation） neural network can effectively solve the neural network slow convergence speed, easily falling into the master problem, can make accurate diagnosis for the failure of scraper conveyor speed reducer.

Debris flow accumulation has the characteristics of loose and broken, low strength, poor stability and so on. When the tunnel passes through the debris flow accumulation area, it is easy to bring major safety hazards to the construction site. Based on the engineering background of Gangou tunnel crossing debris flow accumulation area in the fourth bid of Jiumian expressway, this paper establishes a numerical calculation model, studies the large deformation characteristics of tunnel surrounding rock in debris flow area, determines the reasonable reinforcement range of tunnel surrounding rock, and puts forward the comprehensive control technology of tunnel passing through debris flow accumulation body combining surface stability and underground reinforcement based on simulation results and field experience. The numerical results show that the deformation of surrounding rock and ground surface can be effectively controlled. The rationality of the proposed control measures is verified by field monitoring, which provides a reference for surrounding rock control of tunnel under type conditions.

Subgrade filling of high-speed railway will cause additional settlement and deformation of existing lines.In this paper,using the finite element analysis platform (Taxis 2D) and considering the settlement of the existing line itself, This paper analyzes the impact of the new and old subgrade lap type and the layer filled this lesson of the new subgrade on the implementation of the existing subgrade. The results illustrate the following points:(1) Compared with different overlapping surface types, different filling those points have a greater impact on the settlement of the existing line; (2) The height of the steps is 0.6m and the width is 1.0m.In the subsequent layered filling construction process, each level The loading capacity of 30cm is more reasonable, which can effectively control the influence of the existing line on the additional settlement of the existing railway. The research results can provide a reference for the optimization of similar roadbed width construction.

In the power system, live workers need to complete various tasks such as heat treatment of the draft plate in a strong electric field. The inaccurate estimation of the wire load increases the labor load of the operators and can cause safety accidents such as wire disconnection and grounding short-circuit. This paper proposes a set of simple and easy-to-use live working mechanics calculation software to assist the dynamic analysis of the live working load of transmission lines, rationally select working tools, and improve the safety of live working.

The work load of the traditional calculation method of safety distance check and circuit mechanics calculation is huge inefficiency, this paper presents a set of software of safety analysis and mechanics calculation for live working, the electrical and mechanical parameters of live working transmission lines are obtained, the feasibility of operation is analyzed, working tools are reasonably selected to improve the safety and efficiency of live working, it is of great significance to reduce the emergency response time, the electric safety distance check and the line mechanics calculation methods.

The effect of different aging times (1 day, 3 days, 5 days and 7 days) on the combustion performance and mechanical properties of nitroguanidine propellants was studied.Through the mechanical properties test of impact and compression and closed bomb test of the prepared propellants, it was found that the relative steepness of the propellants aged for 3 days under normal and low temperature conditions was all less than 1;Under normal and low temperature conditions, the impact strength of propellants aged for 5 days was the largest;Propellants aged for 7 days had the highest compressive strength at low temperatures and propellants aged for 1 day had the highest compression rate at low temperatures.Comprehensive research results show that aging time of three days has a better improvement in the combustion performance and mechanical properties of the propellants.

With the application of the live working method of the zero phase potential of the working phase more and more widely, the safety of the live working operators is urgently needed for research. Considering the influence of electric shock time and frequency on the allowable current of the human body, the safe current is analyzed during live operation, and it is concluded that in the frequency range of 50~60Hz, the current below 50mA can basically guarantee that it will not die after electric shock. In the three scenarios where the insulator maintenance personnel accidentally touch the ground, the grounding wire shocks the electric shock and the charged electric shock of the tower, the human body electric shock is further analyzed. Finally, based on the CDEGS, the model of the human body contacting the grounding conductor is established. The simulation verifies the influence of the allowable current on the time and frequency of the human body withstand current under the zero potential state through the contact voltage diagram and the danger degree diagram.

When the live working is carried out in the distribution network, the zero-potential charging operation is often used. The safety of zero-potential live working is closely related to the measurement distance error. The influence of the measurement error of the zero-potential live working point on the operating phase voltage needs to be studied. Based on the Floyd algorithm, a method for calculating the shortest electrical distance from the operating point to the substation is proposed. The sub-station is centered on the branch nodes of the line to form the distance matrix, and the Floyd algorithm is used to calculate the shortest electrical distance from the working point to the substation. The working phase injection voltage is further calculated based on the zero phase potential characteristics of the operating phase. Finally, based on the PSCAD, the system model is established. The simulation concludes that the distance between the substation and the working point is less than 20m, and the operating point voltage can still be below the safe voltage.