Search

ObjectivesThe localization of core components of heavy-duty gas turbines holds significant importance for technological innovation, industrial upgrading, and even national security. As a typical hot-end component of heavy-duty gas turbines, the performance of the turbine first-stage rotor blade directly determines the efficiency and reliability of the gas turbine. Therefore, the structure of the first-stage turbine blades of a certain heavy-duty gas turbine was optimized.MethodsBy increasing the number of bamboo nodes in the blade body, the blade cooling hole structure was optimized, and the thermal barrier coating was used to improve the blade coating. The temperature, stress distribution and aerodynamic efficiency of the blades before and after optimization under the service condition of the blade were compared and analyzed by fluid calculation and finite element calculation.ResultsHeat transfer efficiency inside the blade is enhanced by optimization of turbulent structure. Under the condition of the same inlet pressure of the cooling air, the surface temperature of the optimized blade is reduced by more than 50 ℃. Since the shape of the blade is not changed, there is little influence on the aerodynamic efficiency. Compared with the blades without optimization, the maximum equivalent stress and equivalent total strain of the optimized blade during service are significantly reduced.ConclusionsBy optimizing the cooling structure and upgrading the protective coatings, the reliability of the blades in high-temperature can be significantly improved. The research results provide a theoretical basis for the localization of gas turbines.

Objective Accurate short term passenger flow prediction is of great significance to improve the operation and management efficiency of the ultra-large scale of urban rail transit network. However, the current research on deep exploration of the spatio-temporal correlations is still insufficient. Therefore, according to the spatio-temporal law of short term passenger flow, a STGCN (spatio-temporal graph convolutional neural network) model based on spatio-temporal correlation characteristics of passenger flow is proposed. Method Firstly, the spatial correlation of ultra-large scale urban rail transit network is captured by ChebyNet （Chebyshev graph convolutional network）, and the temporal correlation of the passenger flow under multi-temporal correlation characteristics is explored with the help of GRU (gated recurrent unit). Secondly, the correlation of the historical passenger flow data of the station to be predicted and that of OD (origin-destination) passenger flow data are analyzed to extract the spatio-temporal correlation deeply. Finally, a STGCN model is established in combination with the spatio-temporal correlation characteristics of the passenger flow. Result & Conclusion Taking Jiangsu Road Station of Shanghai Metro Line as an example, a short-term inbound passenger flow prediction is conducted. The result shows that the prediction accuracy with spatio-temporal correlation characteristic parameters is 16% higher than that without the parameters, indicating a better prediction effect.

Chaperonin-containing T-complex polypeptide 1 (CCT) is a molecular chaperone in the cytoplasm of eukaryotic cells involved in the correct folding and assembly of proteins, which plays an important role in cold-stress response. This study cloned two transcripts of Pinctada maxima CCT-beta composed of 1,829 bp (CCT-betal) and 2,289 bp (CCT-beta2), respectively, using rapid amplification of cDNA ends. Both transcripts possess 105 bp of 5' noncoding region and the same coding region, bul contain different 3' noncoding regions of 591 bp (CCT-betal) and 131 bp (CCT-beta2), respectively. The open reading framework (ORF) consisted of 1,593 bp that encodes 530 amino acids. The CCT-beta protein has three conserved functional domains (equatorial, apical, and intermediate domains), three CCT-family signature sequences, nine conserved ATP-binding sites, one DEAD box motif, and three protein-binding sites. The CCT-beta is highly conserved, with the cDNA homologies between P. maxima and Crassostrea gigas, Danio rerio, and Homo sapiens being 90.4%. 76.8%, and 75.8%, respectively. Real-time quantitative PCR showed that CCT-beta was differentially expressed in different organs of P. maxima, with mRNA contents declining from the gill, adductor muscle, foot, labial palps, mantle, and heart to hepatopancreas. Under cold stress, CCT-beta mRNA expression in various organs increased, but the patterns of increase varied among organs. The transcriptional level of CCT-beta peaked at 6h in the heart and hepatopancreas, and decreased significantly at 12h. In the adductor muscle, gill, and mantle, CCT-beta mRNA increased significantly at 12h and declined markedly at 24h in cold stress-exposed animals. These results indicate that CCT-beta is a cold-stress response gene, but the response pattern varies among organs. Organs with low CCT-beta basal expression may be more sensitive to cold stress than the organs with relatively high basal expression content. KEY WORDS: Pinctada maxima, CCT-beta, cDNA, cold stress, INTRODUCTION Chaperonin-containing T-complex polypeptide 1 (CCT) is a kind of type II chaperonin that is localized in the cytoplasm of eukaryotes (Frydman et al. 1992, Gao et al. 1992, Lewis [...]

Background In recent years, the number of diabetics in China ranks first in the world. While recommending metformin as the first-line hypoglycemic drug, the Chinese Clinical Guidelines for the Prevention and Treatment of Type 2 Diabetes in the Elderly (2022 edition) emphasize "patient-centere" and select appropriate second-line hypoglycemic agents for combination administration according to the clinical characteristics and preferences of patients. Because there are great differences in the prevalence rate and life behavior of type 2 diabetes between the north and the south of China, whether there is a difference in the second-line drug preference of patients with type 2 diabetes between the two places remains to be further demonstrated. Objective To analyze the difference of second-line drug preference among patients with type 2 diabetes mellitus in North and South China, and to provide empirical evidence for clinical and health management decision-making. Methods The study adopts a Discrete Choice Experimental design, Mixed Logit Model was used to analyze drug preference of patients with type 2 diabetes in the north and south of China based on Multi-stage random cluster sampling and convenient sampling, from October 2021 to January 2022. Results In this study, 1 443 questionnaires were distributed, and 1 388 were valid, with an effective recovery rate of 96.19%. Logit model analysis showed that the effect of blood sugar control, the risk of hypoglycemia, the risk of gastrointestinal side effects, whether the cardiovascular system can be protected, the way of taking drugs and the out-of-pocket cost/month were the influencing factors of the second-line drug preference of southern patients (P

Objective With the increasing automation levels in urban rail transit, drivers responsible for operation in GOA2 (semi-automated train operation) mode become the multitasking personnel responsible for monitoring and inspecting compartments in GOA4 (unattended train operation) mode. The emergency disposal operation procedure has changed as a result. To achieve a more refined analysis and evaluation of urban rail transit train operations in the GOA4 mode, it is necessary to conduct an in-depth study on the quantitative assessment method for the emergency disposal operation complexity in terms of key driving post personnel. Method Based on standardized operating procedures, the WDA (work domain analysis) method is used to establish an information structure diagram for key driving post personnel. The emergency disposal operation complexity in terms of key driving post personnel under both GOA2 and GOA4 modes is analyzed from four aspects of information quantity, operation logic, operational scale, and overall complexity. Using door malfunction emergency disposal operations as example, the emergency disposal operation complexity for key driving post personnel in both modes is calculated, and two-tailed Pearson test is carried out for site standardized operational score rate correlation verification. Result & Conclusion The correlation test results show that the correlation coefficient of vehicle door fault emergency disposal operations is -0.827, significance level is 0.042, the complexity of the operation and the score rate is negatively correlated, validating the effectiveness of the SC (step complexity) model.

为开发具有较强耐水性的环保可再生胶黏剂，以环氧大豆油（ESO）为原料，选用顺丁烯二酸酐(MA)为固化剂，乙酰丙酮锌〔Zn(acac)2〕为催化剂，制备ESO木材胶黏剂，同时制备了杨木胶合板，考察了MA添加量对胶黏剂性能的影响，通过DSC分析优化了催化剂添加量，对胶黏剂进行了红外光谱和TG/DTG分析，并利用正交实验对热压工艺进行了优化。结果表明：当MA添加量为27%时胶黏剂性能达到最佳；催化剂的最优添加量为3%；通过红外光谱和TG/DTG分析证明ESO与MA发生了交联固化反应；最佳热压工艺为热压温度150 ℃、热压时间10 min、热压压力2 MPa、涂胶量320 g/m2，在此条件下湿态胶合强度为1.613 MPa，符合国家规定的普通胶合板Ⅱ类板要求（≥0.70 MPa）。该胶黏剂制备方法具有简单、高效、环保等优势,是实现ESO在木材产品生产中可持续应用的一种很有前景的策略,具有很大的工业应用潜力。In order to develop environmentally friendly and renewable adhesives with excellent water resistance, with epoxy soybean oil (ESO) as raw material, maleic anhydride (MA) as curing agent and zinc acetylacetonate (Zn(acac)2) as catalyst, ESO wood adhesive and poplar plywood were prepared. The effect of MA dosage on the performence of adhesive was studied. The catalyst dosage was optimized by DSC analysis, and the adhesive was analyzed by infrared spectroscopy and TG/DTG. Then, the hot-pressing process was optimized by orthogonal experiment. The results showed that the best adhesive performance was achieved at 27% of MA dosage. The optimal dosage of catalyst was 3%. Infrared spectroscopy and TG/DTG analysis proved that ESO underwent crosslinking and curing reaction with MA. The optimal hot-pressing process conditions were obtained as follows: hot-pressing temperature 150 ℃, hot-pressing time 10 min, hot-pressing pressure 2 MPa, and glue spread 320 g/m2. Under these conditions, the wet bonding strength was 1.613 MPa, which was in line with the national requirement of Class Ⅱ ordinary plywood（≥0.70 MPa）. The preparation method of adhesive has advantages such as simplicity, efficiency and environmental friendliness, and it is a promising strategy for achieving sustainable application of ESO in wood product production, with great industrial application potential.

Objective Improving the service level to the passengers and ensuring safety are the core purpose of the facility layout and operation management of urban rail transit station. To design the station facility scientifically, the basic characteristics and patterns of the pedestrian following behavior need to be studied. Method Based on the pedestrian trajectory, a description model of pedestrian following behavior and its characteristic parameters are proposed, and a controllable experiment is designed to simulate the pedestrian following behavior in one way passage of the urban rail transit station. The pedestrian following trajectory is extracted from the collected video data, and the characteristics and patterns of the parameters such as pedestrian following speed difference, time interval, horizontal and longitudinal spacing are deeply analyzed when the following behavior occurs. The effects of the four factors i.e. pedestrian density, passage width, gender and familiarity to the environment on the pedestrian following behavior are studied. Result & Conclusion The lower the pedestrian density, the smaller the average following speed difference and the shorter the average following time distance. The passage width has no significant effect on the following behavior characteristic parameters. All the values of the characteristic parameters of the opposite sex are larger than those of the same sex. The values of the characteristic parameters of the pedestrians who are not familiar with the environment are more discrete than those familiar with the environment.