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Pneumatic launch systems for Unmanned Aerial Vehicles (UAVs), including mechanical and pneumatic systems, are complex and non-linear. They are subjected to system parameters during launch, which leads to difficulty in engineering research analysis. For example, the mismatch between the UAV parameters and the parameter design indices of the launch system as well as the unclear design indices of the launching speed and overload of UAVs have a great impact on launch safety. Considering this situation, some studies are presented in this paper. Taking the pneumatic launch system as a research object, a pneumatic launcher dynamic simulation model is built based on co-simulation considering the coupling characteristics of the mechanical structure and transmission system. Its accuracy was verified by laboratory test results. Based on this model, the paper shows the effects of the key parameters, including the mass of the UAV, cylinder volume, pressure and moment of inertia of the pulley block, on the performance of the dynamic characteristics of the launch process. Then, a method for matching the parameter characteristics between the UAV and launch system based on batch simulation is proposed. The set of matching parameter values of the UAV and launch system that satisfy the launch take-off safety criteria are calculated. Finally, the influence of the system parameters of the launch process on the launch performance was analysed in detail, and the design optimised. Meaningful conclusions were obtained. The analysis method and its results can provide a reference for engineering and theoretical research and development of pneumatic launch systems. [ABSTRACT FROM AUTHOR]

Use of atomic hydrogen as a probe helps differentiate as-deposited and annealed contacts of Pd on p-type GaAs with similar ohmiclike characteristics at room temperature. Determination of current-voltage and capacitance voltage characteristics at low temperatures supports the results of the hydrogen-probe method. Low barrier height is responsible for the ohmiclike behavior of as-deposited contact.

Preparing various types of coatings to strengthen the surface of materials is a significant technique to increase the materials' service performance，and the addition of different content of hard phase is conducive to further improve the properties of coatings.The Fe50Mn30Cr10Co10 high-entropy alloy coating with different VC content were prepared through selective laser cladding process，and the effects of VC content on the microstructure，the phase structure，the hardness and the creep properties of the coatings were researched by scanning electron microscope，X-ray diffractometer，nano indentation instrument，etc.Results showed that the coating structure was obviously refined with the increase of VC content.There was no effect on the phase structure of the coating，because of VC being dissolved in FCC lattice.The hardness of the coating increased，owing to the increase of solid solution strengthening effect.Particularly，with the increase of VC content，the creep value of the coating decreased，which was very beneficial to improve the creep performance of the coating material.This provided an important basis for strengthening the properties of the coating of high-entropy alloy by adding VC hard phase.

With the continuous promotion of the construction of unmanned automated fully intelligent mechanized working faces, higher technical requirements have been put forward for the automation control function of the hydraulic support electrohydraulic control system. The electrohydraulic control technology developed in China has problems such as low communication speed, delayed response, and poor reliability in meeting the requirements of intelligent production technology. An end controller for the electrohydraulic control system of hydraulic support based on a 32-bit processor has been developed. A communication architecture of the end controller based on industrial Ethernet and CAN bus has been designed. According to the technical requirements of intelligent perception, intelligent decision-making, and automatic control for unmanned intelligent mechanized working faces, parameter inspection, parameter modification, online upgrade, and control functions of automatic follow-up have been designed in the end controller. In order to meet the requirements of standardization and normalization of data in the hydraulic support electrohydraulic control system in intelligent fully mechanized working faces, the end controller can encode the data generated by the hydraulic support electrohydraulic control system according to the data encoding standard based on tag numbers. Through the experiment on the 'three machines' experimental platform of fully mechanized working faces, the results show the following points. The entire process from issuing inspection instructions to receiving data from 27 support controllers on the experimental platform takes 1.8 s for the end controller. It is 1.5 s faster than using RS485 communication to achieve parameter inspection. The size of the upgrade program sent by the end controller is 38 KiB and the transmission time is 1.2 s. After testing, it takes 4-6 s for all support controllers in the fully mechanized working face to receive the upgrade command and successfully upgrade together, achieving the expected goal. The end controller can control the corresponding hydraulic support to make correct actions based on the position of the shearer. It can meet real-time requirements.

At present, due to lack of the domestic technical status data management standards for in-service aircraft, the data management is managed by multiple related parties and is not planed as a whole, the data is difficult to correlate and trace, so it cannot ensure efficiency and quality of aircraft logistics. Through the research on S5000F (International specification for in-service data and feedback), which provides a guide for the in-service data management. a framework of the in-service data management for aircraft is constructed, and a data model based on UML(Unified Modeling Language) is constructed as well to perform the data-structured design. A dynamic traceable tool of in service data management is built based on technical status tree and data trace. The results show that the technical status data management framework presented in this paper is feasible and can ensure full life cycle logistic support for aircraft.

Endoscopic retrograde cholangio-pancreatography (ERCP) is one of the primary procedural techniques used for diagnosing biliary and pancreatic diseases. Post-ERCP pancreatitis (PEP) is the most common complication of ERCP, which resulted in prolonged hospitalization and potential risk of patients' lives, especially in severe cases. Understanding the risk factors associated with PEP is of paramount importance for its prevention. Currently, recognized risk factors for PEP encompass both patient-related factors and ERCP procedure-related factors. By considering these risk factors, implementing appropriate preoperative, intraoperative, and postoperative interventions could effectively reduce the incidence of PEP. In this article, we concisely summarized the common risk factors and preventive methods for PEP, offering valuable insights for healthcare professionals in clinical practice.

Currently, research on the intrinsically safe features of intrinsically safe circuits mostly relies on the IEC spark experimental device as the experimental platform. The research only analyzes the discharge features of a single capacitor or inductance circuit. There are problems such as poor applicability and high requirements for experimental conditions. There is a lack of research on the intrinsically safe features of hybrid intrinsically safe circuits. To solve this problem, based on GB/T 3836.4-2010 Explosive Atmospheres - Part 4: Equipment Protected by Intrinsic safety Type 'i', a short circuit transient energy experiment is carried out with the hybrid circuit under the cutoff type protection mode as the experimental object. By analyzing the release process of short circuit transient energy, a mathematical model of short circuit transient energy is established. The paper analyzes the effects of capacitance, inductance, power supply voltage, and protection time on short circuit transient energy in the equivalent mathematical model. The Matlab simulation results show that as the capacitance and inductance increase, the transient energy of the short circuit will gradually increase and eventually approach a stable value. Increasing the power supply voltage will significantly increase the short circuit transient energy. Shortening the action protection time can effectively reduce transient energy. But its effect is only significant when the protection time is less than the critical time. An intrinsically safe power supply is developed based on a mathematical model of short circuit transient energy. The short circuit experiments are conducted. The experimental results show that the waveform of short circuit current and voltage is basically consistent with theoretical analysis. The transient energy of short circuit is 33.22 μJ, which meets intrinsic safety requirements and can provide a reference for the design of intrinsically safe power supplies.

Administrative division adjustments (ADAs) have been key in optimizing regional resource allocation and spatial governance. The impacts of ADAs on regional ecosystems remain unclear in the "green turn" process of China's urbanization. This research chose Nansha District, Guangzhou, as a study area due to its frequent ADAs and its changing location in the Guangdong-Hong Kong-Macao Greater Bay Area in the past 30 years and investigated the relationship between Nansha's ADAs and the changing Ecosystem Service Values (ESVs) from 1990 to 2020 through applying the equivalent factors, hotspot analysis, and gravity analyses. The study reveals that in the rapid urbanization process, frequent ADAs have affected regional ecosystems and ESV changes, with pros and cons. First, there were strong relations between the ADAs and regional ESVs during 1990-2020. The total ESV of Nansha decreased first but increased later, then again decreased according to the ADAs that happened in 1990-2000, 2000-2010, and 2010-2020. Second, land uses in Nansha District have varied because of urban sprawl since the ADAs. Ecosystems were degrading as a result of the increase of construction land and the depletion of farmland and woodland areas. . Third, at the same time, gaining higher administrative privilege had facilitated local governments to promote the restoration of the ecosystem, particularly the enhancement of wetlands, which led to a growth in regional total ESVs in Nansha. It reveals that regional ecosystem services will undergo a phased, multi-level, and multi-faceted change because of the changes in local governance, the diversification of land uses, and the various land development models. This study fills the gap in studying relationships between changes in ecological system services and ADAs at the district (or county) level. The regional ecosystem services of Nansha are sustainable, as more than 40 percent of the total land is ecological. Therefore, it suggests Nansha District Government should take the chance of ADAs to enhance its privilege in regional spatial governance by cooperating with other local governments in the Greater Bay Area through constructing, governing, and sharing a high-quality ecological conservation and restoration landmark of the rivers and shorelines. It also calls for more attention to the impacts in different phases with multiple levels and dimensions caused by the roles of governments and the land development models rather than merely assessing the changing land use structures and the overall ESV.

Objective To develop an MATLAB algorithm for the automated measurement of motor neuron (MN) neurites and apply this algorithm to evaluate the organophosphate flame retardant tris (2-chloroethyl) phosphate (TCEP) on the growth of MN neurites. Methods Human embryonic stem cells were induced to gradually differentiate into MN. After the neurites were labelled with βⅢ-tubulin for fluorescence image processing, an image process algorithm was developed to automatically analyze the neurite and changes in neurite network area after pollutant treatment. During MN differentiation, the cells were treated with different concentrations of TCEP (0, 25, 50 and 100 μmol/L). Results MNs were successfully induced with the expression of choline acetyltransferase. The developed image recognition algorithm could analyze images in batches, and calculate the pixel area occupied by neural network, and reserve weak neurites by optimizing neurite retention threshold to improve the accuracy of measurement. The quantification data from image process algorithm showed that TCEP significantly decreased the percentage of neurite network area since the dose started from 50 μmol/L (P < 0.05). Conclusion An image process algorithm is successfully developed for automated measurement of neurites based on the human MN neurite model. Moreover, this algorithm can be applied to the toxicity assessment of TCEP.

This paper precisely explores the structure and characteristics of college students’ healthy human capital and its influencing factors. It aims to enhance students’ positive and healthy mindset and promote optimism in life and learning. A solid analytical framework is constructed by sorting out the ordered multicategorical logistic regression model and parameter estimation methods and the application steps of the propensity score matching model. College students from ten colleges and universities in Hunan Province were selected as research subjects, and a questionnaire was designed to assess their healthy human capital. The specific factors affecting college students’ healthy human capital accumulation were analyzed in depth through the probability density analysis of propensity score matching, standard support hypothesis testing, and the parallel line test and regression results of the ordered multicategorical regression model. The findings show that the curves of the experimental and control groups after propensity score matching almost overlap in the [0.2,0.4] interval, indicating the method’s validity. A more important finding is that the number of college students with poor self-assessed physical health is 8.063 times higher than that of college students with self-assessed mental health as good, which emphasizes the significant impact of mental health on healthy human capital. Therefore, to effectively improve the health human capital of college students, students, families and universities must form a linkage mechanism and work together to cultivate college students’ health awareness.

The shimmy of the front landing gear of an aircraft usually occurs in the process of taking off or landing,which endangers the stability and maneuverability of the aircraft and is a serious aircraft fault. In this paper,based on the theorem of moment of momentum,a mathematical model of shimmy considering landing gear side bending and torsion is established for a certain type of UAV. The different dynamic models when using traditional oil damping damper and electromagnetic damping damper are discussed. For the traditional oil damping damper,the equivalent linear model is used to obtain the upper and lower boundaries of the critical stability damping curve. For the nonlinear model of electromagnetic damping damper,the bifurcation analysis theory is used to determine the shimmy stability area. Results show that excessive shimmy damping can not suppress shimmy,and the stable region of shimmy on the parameter plane can be obtained. It can provide some references for the design of landing gear shimmy reduction.

Background With the rapid population aging in China, cognitive impairment in older adults has become a growing public health concern. Objective To examine the association between nighttime sleep duration and cognitive impairment among community-dwelling older adults. Methods Data were derived from the cohort of Older Adult Health and Modifiable Environmental Factors established in Fuyang City from July to September 2018, among whom a total of 4 837 older adults with complete data on cognitive function and sleep time were included in this study. General demographic characteristics〔gender, age, living area (urban or rural), education level, occupation, marital status〕, living habits, the history of chronic diseases, sleep duration, and overall cognitive function were extracted. Binary Logistic regression models were used to analyze the association between nighttime sleep duration and cognitive impairment. Restrictive cubic splines were used to further determine potential dose-response relationships between them. Results The participants had a mean nighttime sleep duration of (6.95±1.75) hours, among whom 1 773 (36.65%) slept ≤6 hours per day, 2 088 (43.17%) slept >6-8 hours per day, and 976 (20.18%) slept >8 hours per day. The detection rate of cognitive impairment was 37.44% (1 811/4 837). After adjusting for gender, age, living area, education level and other confounding factors, the detection rate of cognitive impairment was 1.26〔95%CI (1.09, 1.46) 〕 times higher in older adults with nighttime sleep duration of ≤6 hours, and was 1.22〔95%CI (1.03, 1.46) 〕 times higher in older adults with nighttime sleep duration of >8 hours than in those with nighttime sleep duration of >6-8 hours (P8 hours was 1.35〔 (95%CI (1.06, 1.72) 〕 times higher than in those with nighttime sleep duration of >6-8 hours (P6-8 hours (P

ObjectiveMethods·The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database and the GSE15471 dataset in Gene Expression Omnibus (GEO) database were used to analyze the SNX1 mRNA expression in PDAC and normal pancreas tissues. Immunohistochemistry staining (IHC) was used to detect the SNX1 expression in PDAC and para-carcinoma tissues. The mRNA and protein levels of SNX1 in hTERT-HPNE cells and PDAC cells were detected by quantitative real-time PCR (qPCR) and Western blotting. CCK8 method, plate clonal formation experiment, cell scratch assays and flow cytometry (FCM) were used to detect changes of the proliferation, migration and apoptosis levels in AsPC-1 and Capan-1 cells caused by transfection siRNAs. Capan-1 cell line with stable knockdown of SNX1 was constructed, and the subcutaneous tumorigenesis experiment in nude mice was performed to detect the effect of SNX1 knockdown on the proliferation capacity of cells in nude mice. Immunofluorescence (IF) was used to determine the distribution of SNX1 in PDAC cells, and TMR-dextran was used to detect the changes of macropinocytosis levels of AsPC-1 and Capan-1 cells induced by transfection siRNAs. Gene Set Enrichment Analysis (GSEA) was performed to predict SNX1 related signaling pathways. The transforming growth factor-β (TGF-β) signaling pathway was selected for subsequent analysis and experimental verification. Capan-1 and AsPC-1 cell lines with stable overexpression of SNX1 were constructed and treated with TGF-β signaling pathway inhibitor Oxymatrine (Oxy). CCK8 method, plate clonal formation experiment, cell scratch assays, FCM and TMR-dextran were used to detect the effects of Oxy treatment on the changes of the proliferation, migration, apoptosis and macropinocytosis levels of the cells caused by SNX1 overexpression.Results·The results of combined analysis of TCGA and GTEx databases showed that the expression of SNX1 mRNA in PDAC tissues was higher than that in normal pancreas tissues, and the results of GSE15471 dataset analysis showed that the expression of SNX1 mRNA in PDAC tissues was higher than that in para-carcinoma tissues (both P=0.000). IHC results showed that the expression of SNX1 in cancer tissues of PDAC patients was also higher than that in para-carcinoma tissues. qPCR and Western blotting results showed that compared with hTERT-HPNE cells, the mRNA and protein levels of SNX1 in PDAC cells were up-regulated (all P

In this study, a novel structure of layered Ti-B4C/AA6061 composite with different B4C particles contents was designed and fabricated by pulse current sintering, and its microstructure and mechanical properties were investigated. It is found that the heterogeneous interface bonds well without voids and cracks and the B4C particles exhibit a homogenous distribution in AA6061 matrix. The intermetallic compounds (TixAly) are observed with a thickness of about 1.5 µm between Ti and B4C/AA6061 layers. The yield strength, ultimate tensile strength and elongation to fracture of the layered Ti-B4C/AA6061 composite are obviously enhanced. In addition, the Ti layers and the B4C particles embedded in the matrix play an important role in strengthening mechanisms of the layered composite, and the crack propagation is constrained by layered structure. [ABSTRACT FROM AUTHOR]

Sb distribution in the phases of SiO2 saturated Sb-Fe-O-SiO2-CaO system was determined for the first time through heightemperature experiment and quenching techniques, followed by Electron probe X-ray microanalysis (EPMA) in air (Ptot = 1 atm, PO2 = 0.21 atm). The phases were quantified in the temperature range of 900 °C-1200 °C and the effects of Fe/SiO2 (mass fraction) and CaO/SiO2 (mass fraction) on Sb2O3 content in the Sb-Fe-O-SiO2-CaO system were investigated at 1200 °C. The results indicated that the Sb-containing phase primarily existed in the solid solution phase at 1200 °C. With the increase of temperature from 1100 °C to 1200 °C, the Sb2O3 content in the solid solution phase increased drastically from 7.52 wt% to 17.36 wt%. Lowering the values of CaO/SiO2 and Fe/SiO2 in the smelting process effectively reduced Sb2O3 content in the slag. The verification of the experiment results suggested that the antimony content in slag was 0.57 wt%, the crude antimony yield rate was lower than 4%, and the crude antimony grade was beyond 94 wt%, which meant that the reduction of antimony content in the slag could be achieved. [ABSTRACT FROM AUTHOR]

The stability of urban rail transit vehicle-ground integrated communication system is one of the biggest problems faced by metro operatings. In order to improve the security and reliability of communication, the wireless vehicle-ground communication technology of urban rail transit has been upgraded from WLAN to long-term evolution technology(LTE). On the basis of comprehensive analysis of the LTE technology of urban rail transit vehicles, a train access unit for the LTE-M wireless private network vehicle-ground communication equipment is proposed, according to the requirements specification of urban rail transit vehicle-ground integrated communication system. It adopts 1.8 GHz TD-LTE proprietary mobile network and VPN security access technology to establish a secure and reliable communication link at the vehicle-ground end. Through the communication beating test, the train access unit can communicate with the ground server through the core network of the private network, the communication rate is stable, the delay is less than 150 ms and no packet loss phenomenon appears. It can meet the data access service requirements of carrying CBTC control service, passenger information system, video surveillance system, etc.

This article uses BIM technology to simulate HVAC in a commercial building. And use fractional differential equations to verify the set temperature, humidity, and other related parameters. The experiment takes an air-conditioned room model as the research object and uses the thermodynamic characteristics to establish a dynamic mathematical model of differential equations. Research shows that the multiple electric heat pump equipment aggregation groups discussed in this article are a good resource for user-side demand response. The air-side flow rate disturbance of the building HVAC has the greatest impact on the heat transfer of the surface cooler. As the air velocity increases, the rate of increase in heat exchange will decrease.

Objective To investigate the therapeutic effect and prognostic significance of lateral lymph node dissection (LPLND) in patients with lateral lymph node (LPLN) metastasis. Methods The clinicopathological data of rectal cancer patients who underwent total mesorectal excision (TME) combined with LPLND and pathologically confirmed as LPLN metastasis after operation were retrospectively analyzed. The clinicopathological characteristics and metastasis rules of patients with LPLN metastasis were discussed, and the survival prognosis after LPLND was analyzed. Results A total of 102 rectal cancer patients with pathologically confirmed LPLN metastasis were included. The common sites of LPLN metastasis were internal iliac vessels lymph nodes (n=68, 66.7%), followed by obturator lymph nodes (n=44, 43.1%), and common iliac vessels or external iliac vessels lymph nodes (n=12, 11.8%). There were 10 patients (9.8%) with bilateral LPLN metastases, and the mean number of LPLN metastases was 2.2±2.4, among which 16 patients (15.7%) had LPLN metastases number≥2. The 3-year OS (66.8% vs. 7.7%, P < 0.001) and DFS (39.1% vs. 10.5%, P=0.012) of patients with LPLN metastases to the external iliac or common iliac lymph node were significantly lower than those with metastases to the internal iliac or obturator lymph node. The multivariate analysis showed that LPLN metastasis to external iliac or common iliac lymph node was an independent risk factor both for OS (HR=3.53; 95%CI: 1.50-8.31; P=0.004) and DFS (HR=2.40; 95%CI: 1.05-5.47; P=0.037). Conclusion LPLN mainly metastasizes to the internal iliac or obturator lymph node areas. The survival of patients with metastasis to the external iliac or common iliac lymph node cannot be improved by LPLND, and thus systemic comprehensive treatment is often the optimal treatment option.

OBJECTIVE: Currently, detection of SARS-CoV-2 RNA is standard in the diagnosis of COVID-19 (2019-nCoV). However, reliable and rapid serological diagnostic methods to screen SARS-CoV-2 infected patients, including those who do not have overt symptoms, are urgently needed. Most studies have described serological tests based on the detection of SARS-CoV-2- specific IgM and IgG. Here, we attempted to systematically analyze the positive rates and comprehensive diagnostic efficacy of IgM and IgG in response to SARS-CoV-2 infection. MATERIALS AND METHODS: By systematically searching PubMed, medRxiv, bioRxiv and other databases, studies regarding the detection of peripheral blood IgM and/or IgG related to SARS-CoV-2 were collected. The positive rate, sensitivity (SEN), specificity (SPE), area under the curve (AUC) and corresponding 95% CIs were obtained by weighted quantitative mergence, and the source of heterogeneity was explored by performing a subgroup study and sensitivity analysis. RESULTS: A total of 30 studies were included, which were comprised of 3856 confirmed SARS-CoV-2 RNA positive cases, 368 suspected RNA negative cases, 1167 asymptomatic carriers, and 2526 RNA negative controls. The corresponding meta-analysis showed that in confirmed cases with 2019-nCoV, the positive rates of single IgM, single IgG and their joint detection related to SARS-CoV-2 were 61.2% (95% CI: 53.4%-69.0%), 58.8% (95% CI: 49.6%-68.0%) and 62.1% (52.7%-71.4%), respectively. In suspected RNA negative cases, the positive rates of single IgM, single IgG and their joint detection were 29.0% (95% CI: 14.0%-44.0%), 37.0% (95% CI: 20.0%-55.0%) and 55.0% (95% CI: 19.0%-90.0%), respectively. Interestingly, IgM/IgG detection also demonstrated a positive rate of 19% (95% CI: 10.0%-27.0%) in asymptomatic cases. Using RTPCR test as reference, the AUCs of IgM, IgG and IgM/IgG in the diagnosis of 2019-nCoV infection were 0.9656, 0.9766, and 0.9838, respectively. The stratified analyses showed that among confirmed cases with 2019-nCoV, the positive rates of IgM and IgG were 27.3% (95%CI: 19.8%-34.8%) and 22.3% (95% CI: 11.3%-33.3%), respectively, 0-7days following the onset of symptoms, whereas the positive rate of parallel IgM/IgG testing attained 39.3% (95% CI: 24.2%-54.4%). Moreover, the efficacy of antibody testing based on CLIA (chemiluminescence enzyme immunoassays) in diagnosing 2019-nCoV infection was higher than that of LFIA (lateral flow immunoassays) and ELISA (enzyme linked immunosorbent assay). CONCLUSIONS: IgM, IgG and their joint testing exhibited high clinical value in the diagnosis of 2019-nCoV, which may assist in making up for the deficiency of throat swab RNA tests. [ABSTRACT FROM AUTHOR]