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In this paper, we develop an equilibrium framework to explain the characteristics of volatility index (VIX) futures prices and returns across maturities. In the framework, the investors prefer VIX futures with specific maturities, and the arbitrageurs optimize portfolios based on mean-variance preferences. The model-implied futures prices are affected by the variance and demand risk factors. Theoretical and empirical analyses show that incorporating jump risks helps to explain the higher-order moments of futures and that including the demand factor improves futures pricing performance.

Abstract Background As the social economy has developed and population mobility has increased, differences in the Human immunodeficiency virus type 1 (HIV‐1) genotype distribution among men who have sex with men (MSM) have become apparent in the provinces and cities across China. The high variability and drug resistance characteristics of HIV‐1 can lead to the widespread spread of resistant strains, which may also result in antiretroviral therapy failure and an increase in the mortality rate. Objective The genotypic drug resistance characteristics and HIV‐1 transmission risks among HIV‐1‐infected MSM in Guiyang, Guizhou Province were analyzed in the current study. The aim of the study was to provide a scientific basis for preventing the spread of HIV‐1 strains among MSM and develop intervention measures. Method A cross‐sectional study was conducted at the Guiyang Public Health Clinical Center. A total of 181 HIV‐1‐infected MSM who not received treatment at the center between 1 January 2020 and 31 December 2022 were selected. The HIV‐1 pol region gene fragment, including the protease and reverse transcriptase regions, was amplified by nested PCR and RT‐PCR. The maximum likelihood method was used to construct a phylogenetic tree for analyzing the HIV‐1 genotypes in MSM. HIV‐1 genotypic resistance was evaluated using the Stanford University HIV drug resistance database. A molecular transmission network of HIV was constructed and the risk of HIV‐1 transmission was determined. Results We successfully amplified 173 pol gene sequences from blood samples obtained from 181 patients. The main subtype was CRF07_BC (60.69% [105/173]), followed by CRF01_AE (26.59% [46/173]), CRF08_BC (4.05% [7/173]), CRF55_01B (4.62% [8/173]), B (3.47% [6/173]), and C (0.58% [1/173]). The distribution of HIV‐1 genotypes in MSM showed that there was a significant difference in the genotype composition of HIV‐1‐infected MSM according to registered residences and ages (p 30 years of age. Multivariate logistic regression analysis of risk factors for drug resistance in HIV‐1‐infected MSM showed that the overall prevalence of pretreatment drug‐resistant species was 12.72% (22/173), and age >30 years, CRF55_01B subtype, and CD4+ T lymphocyte count >350 cells/mm3 were risk factors for drug resistance in MSM HIV‐1 strains. Among the pretreatment drug‐resistant species, non‐nucleoside reverse transcriptase inhibitors with ≥1 drug resistant‐species accounted for 9.25% (16/173), followed by protease inhibitors at 4.05% (7/173) and nucleoside reverse transcriptase inhibitors at 1.73% (3/173). Non‐nucleoside reverse transcriptase inhibitors resistant to the CRF07_BC and CRF01_AE genotypes were predominant. The CRF55_01B genotype was shown to be most likely to carry the V179E mutation. The molecular network included CRF07_BC and B genotypes. The results of multi‐factor logistic regression analysis on the factors affecting the rate of joining the network showed that individuals >30 years of age were less likely to join the network compared to those individuals

Abstract Background Chylopericardium is a rare condition characterized by the accumulation of chyle in the pericardial space. It is most commonly caused by thoracic duct injury. Chylopericardium following esophagectomy is extremely rare but can cause life-threatening complications. This report presents a case of chylopericardium post-esophagectomy, resulting in cardiac tamponade and cardiac arrest. A systematic literature review was also conducted to facilitate the understanding of this rare condition. Case presentation A 41-year-old male was admitted to our hospital with intermediate to highly differentiated squamous cell carcinoma of the mid-thoracic esophagus (clinical T4NxM0). He underwent thoracoscopic-laparoscopic esophagectomy with cervical anastomosis. On postoperative day 1, patient had a cardiac arrest secondary to cardiac tamponade, requiring emergency ultrasound-guided drainage. The drained fluid was initially serous but became chylous after the administration of enteral nutritional emulsion. As a result of significant daily pericardial drainage, patient subsequently underwent thoracic duct ligation. The amount of drainage was substantially reduced post-thoracic duct ligation. Over a period of 2 years and 7 months, patient recovered well and tolerated full oral diet. A comprehensive literature review was conducted and 4 reported cases were identified. Among these cases, three patients developed pericardial tamponade secondary to chylopericardium post-esophagectomy. Conclusion Chylopericardium is a rare but serious complication post-esophagectomy. Prompt echocardiography and thorough pericardial fluid analysis are crucial for diagnosis. Thoracic duct ligation has been shown to be an effective management approach for this condition.

In this study, the Ni/NiO catalyst was demonstrated to enhance the hydrogen storage performance of MgH2. The dehydrogenation of MgH2+10 wt% Ni/NiO started at approximately 180 °C, achieving 5.83 wt% of dehydrogenation within 10 min at 300 °C. Completely dehydrogenated, MgH2 began to rehydrogenate at about 50 °C, absorbing about 4.56 wt% of hydrogen in 10 min at 150 °C. In addition, the activation energies of dehydrogenation and rehydrogenation of MgH2+10 wt% Ni/NiO were 87.21 and 34.84 kJ/mol. During the dehydrogenation/rehydrogenation cycle, Mg2Ni/Mg2NiH4 could promote hydrogen diffusion, thus enhancing the hydrogen storage performance of Mg/MgH2.

The study introduces an innovative three-stage nested power generation system that enables the cascading utilization of LNG cold energy. It makes the most of wasted energy by using ship jacket cooling water (JCW) and exhaust gas (EG) as heat sources, a trans-critical carbon dioxide cycle as internal circulation, and utilizing the pressure exergy of LNG. We choose two azeotrope mixing fluids that match the requirements and create four cases for the outer and middle cycle working fluids in the three-stage nested system. To discover the ideal system performance from the perspectives of exergy (E), economy (E), and environment (E), four cases were subjected to multi-objective optimization using the multi-objective particle swarm optimization technique (MOPSO). Finally, the optimal solution was found by applying the TOPSIS decision-making method. Through comparative analysis, the optimal system is selected among the four optimization results. R170 (22.66%) and R1150 (77.34%) are used as the outer circulating working medium, while R170 (90.86%) and R1270 (9.14%) are utilized as the inter-cycle working fluid. The net output work is 575.75 kW, the optimal exergy efficiency is 46.09%, the optimal electricity production cost is $0.04009 per kWh, the carbon dioxide emissions can be reduced by 36,910 tons, and the payback period is 2.548 years. After optimization, a more energy-efficient and environmentally friendly power generation system is obtained.

This paper introduces a novel portable multi-layer capsule-shaped triboelectric generator (CP-TEG), aimed at optimizing the performance of triboelectric generator technology in terms of miniaturization, modularity, and efficient energy collection. The CP-TEG utilizes a unique multi-layer, stacked structure and an elliptical cylindrical design to increase the effective frictional area and enhance power generation efficiency. Its portable design allows for flexible application in various environments and scenarios. Experimental results demonstrate that the CP-TEG can maintain stable and efficient electrical output under various motion amplitudes and frequencies, and it shows good adaptability to the direction of motion excitation. With a motion amplitude of 7 cm and a frequency of 1.94 Hz, the CP-TEG can charge a 220 μF capacitor to 1.3 V within 100 s. The power generation unit’s output voltage and current are more than three times higher than that of traditional single-layer contact-separation mode triboelectric devices. Particularly, its performance in harvesting energy from human motion underscores its effectiveness as a renewable energy solution for wearable devices. Through its innovative structural design and optimized working mechanism, the CP-TEG demonstrates excellent energy collection efficiency and application potential, offering new options for sustainable energy solutions and development.

Background: Amyloid light-chain (AL) amyloidosis is a multisystem disorder, with cardiac amyloid infiltration being a prevalent manifestation. This study aimed to explore the prognostic value of galectin-3 (Gal-3), a soluble marker associated with fibrosis, inflammation, heart failure, and kidney injury, in patients with cardiac AL amyloidosis. Methods: A total of 60 patients who were diagnosed with cardiac AL amyloidosis from January 2015 to May 2018 were enrolled. The prognostic value of Gal-3 was assessed. Receiver operating characteristic (ROC) curves were used to evaluate the predictive accuracy of Gal-3. A Gal-3 cut-off value was identified to predict survival rates. Results: The ROC curves demonstrated a moderate predictive accuracy of Gal-3 for 0.5- and 5-year survival, with area under the curve (AUC) values of 0.722 and 0.788, respectively. A Gal-3 cut-off value of 15.154 ng/mL was found to predict survival. Kaplan–Meier survival analysis revealed a significant difference in mean overall survival between patients with Gal-3 levels below and above the established cut-off (69.2 months versus 42.1 months, respectively; p = 0.036). Multivariate analysis confirmed that Gal-3 > 15.154 ng/mL remained an independent predictor of survival (HR 2.451, 95% CI 1.017–5.910, p = 0.046). Conclusions: This study suggests that Gal-3 holds independent prognostic value for survival in patients with cardiac AL amyloidosis. Gal-3 could potentially enhance the prognostic capabilities of the current soluble markers, thereby improving the management of cardiac AL amyloidosis. However, further validation in larger prospective studies is warranted.

Abstract Background Acute coronary syndrome(ACS) is the leading cause of mortality and disability worldwide. Immune response has been confirmed to play a vital role in the occurrence and development of ACS. The objective of this prospective, multicenter, observational study is to define immune response and their relationship to the occurrence and progressive of ACS. Methods This is a multicenter, prospective, observational longitudinal cohort study. The primary outcome is the incidence of major adverse cardiovascular events (MACE) including in-stent restenosis, severe ventricular arrhythmia, heart failure, recurrent angina pectoris, and sudden cardiac death, and stroke one year later after ACS. Demographic characteristics, clinical data, treatments, and outcomes are collected by local investigators. Furthermore, freshly processed samples will be stained and assessed by flow cytometry. The expression of S100A4, CD47, SIRPα and Tim-3 on monocytes, macrophages and T cells in ACS patients were collected. Follow-up: during hospitalization, 3, 6 and 12 months after discharge. Discussion It is expected that this study will reveal the possible targets to improve the prognosis or prevent from occurrence of MACE in ACS patients. Since it’s a multicenter study, the enrollment rate of participants will be accelerated and it can ensure that the collected data are more symbolic and improve the richness and credibility of the test basis. Ethics and dissemination This study has been registered in Chinese Clinical Trial Registry Center. Ethical approval was obtained from the Affiliated Hospital of Guizhou Medical University. The dissemination will occur through the publication of articles in international peer-reviewed journals. Trial Registration Chinese Clinical Trial Registry: ChiCTR2200066382.

In order to analyze the relay action process from an imaging perspective and further investigate the bounce phenomenon of relay contacts during the contact process, this paper utilizes a high-speed shooting platform to capture images of relay action. In light of the situation where the stationary contact in the image is inclined and continuously changing, a rotation template matching algorithm based on adaptive weight is proposed. The algorithm identifies and obtains the inclination angle of the stationary contact, enabling the study of the relay contact bounce process. By extracting contact bounce distance data from the images, a bounce process curve is plotted. Combined with the analysis of the contact bounce process, the reasons for the bounce are explored. The results indicate that the proposed rotation template matching algorithm can accurately identify stationary contacts and their angles at different angles. By analyzing the contact status and bounce process of the relay contacts in conjunction with the relay structure, parameters such as the bounce time, bounce height, and time required to reach the maximum distance can be calculated. Additionally, the main reason for contact bounce in the relay studied in this paper is the limitation imposed on the continued movement of the stationary contact by the presence of the relay brackets when the kinetic energy of the contact is too high. This phenomenon occurs during the first vibration peak in the vibration process after the moving contact contacts the stationary contact. The research results provide a reference for further studying the relay contact bounce process, optimizing relay structure, and suppressing contact bounce.

Background The status of patients with HIV/AIDS co-infected with HCV considerably varies in different parts of China. The co-infection of HIV and HCV accelerates the clinical progress of the disease, thereby reducing the patients' quality of life and exacerbating the occurrence of death. Currently, there are relatively few studies on patients with HIV/AIDS co-infected with HCV in Guizhou. Objective To analyze the status of patients with HIV/AIDS co-infected with HCV in Guizhou and its influencing factors and consequently provide basis for its early detection, diagnosis, and treatment. Methods The cases included in this study were a cohort of HIV/AIDS patients who received antiviral therapy (ART) in the public health rescue center of Guangzhou from March 2006 to December 2020. Finally, 3 084 patients who met the study requirements were included. Patients' sex, age, ethnicity, education level, occupation, marital status, route of infection, year of diagnosis, and CD4+ T-lymphocytes before ART and anti HCV levels were collected. Multivariate Logistic regression model were used to identify influencing factors of patients with HIV/AIDS co-infected with HCV. Results Among the 3 084 patients with HIV/AIDS, 202 were co-infected with HCV, and the co-infection rate was 6.55%. There were significant differences in HCV infection rates among patients with HIV/AIDS of different age groups, education levels, occupations, route of infection (P0.05) . The prevalence of HCV infection among HIV/AIDS patients tended to decrease with increasing year of diagnosis and increasing levels of CD4+ T lymphocytes (P

The braiding angle of 3D braided carbon/carbon composites (C/CCs) will change during high temperature fatigue loading, which will affect the fatigue properties of 3D braided C/CCs. In order to realize this dynamic simulation in the high temperature fatigue life prediction of 3D braided C/CCs and further improve the prediction accuracy of high temperature fatigue life of 3D braided C/CCs, a high temperature fatigue life prediction model of 3D braided C/CCs considering the change of braiding angle with fatigue cycle number was established. The establishment of the prediction model mainly includes: a meso-scale representative volume elements (RVEs) of 3D braided C/CCs considering yarn direction and fiber bundle cross-section shape is established at the meso-scale; the high temperature residual stiffness and residual strength models of fiber bundles considering high temperature and stress level are established. Based on the experimental data characteristics of high temperature fatigue residual stiffness of 3D braided C/CCs, a mathematical model of cycle number/braided angles (CN/BAs) is established. The fatigue life prediction model was used to predict the 3D braided C/CCs at 700°C and stress levels of 87% and 85%. The results showed that the prediction error of single flower node was less than 5%. The fatigue life prediction error is less than two times the tolerance.

This study focuses on the Wartsila 9L34DF engine and proposes an integrated system for low-temperature carbon capture using the coupling of cold and hot energy recovery with membrane separation in LNG-powered ships. By utilizing a series dual-pressure organic Rankine cycle (SDPORC) system to recover waste heat from the engine exhaust gases and generate electricity, the system provides power support for the low-temperature carbon capture compression process without consuming additional ship power. To validate the accuracy and reliability of the mathematical model, the simulation results are compared with the literature’s data. Once the model’s accuracy is ensured, the operational parameters of the integrated system are analyzed. Subsequently, working fluid optimization and genetic algorithm sensitive parameter optimization are conducted. Finally, under the optimal operating conditions, the thermodynamic performance and economic evaluation of the integrated system are assessed. The results demonstrate that the net power output of the integrated system is 100.95 kW, with an exergy efficiency of 45.19%. The unit carbon capture cost (UCC) is 14.24 $/ton, and for each unit of consumed LNG, 1.97 kg of liquid CO2 with a concentration of 99.5% can be captured. This integrated system significantly improves the energy utilization efficiency of ships and reduces CO2 emissions.

Given the significant emissions from conventional marine diesel engines, many ship owners are increasingly turning to liquefied natural gas (LNG) as a cleaner energy alternative. In this study, a novel power generation system is proposed for LNG-fueled ships, integrating LNG cold energy and waste heat of the main engine, while considering the pressure of LNG. Firstly, this paper compares the two-stage parallel organic Rankine cycle to highlight its superiority. Secondly, the exergy loss and component cost of the system are analyzed, and the influence of these parameters on the thermal economy of the system is discussed. Finally, the multi-objective genetic algorithm is used to select the system exergy efficiency and electricity production cost (EPC), and the optimal performance point of the system is determined. Based on this, the performances of different literature studies are compared, and the system’s potential impact on the environment is evaluated. The results show that the net output power, thermal efficiency, exergy efficiency, EPC, payback period, and CO2 emission reduction of the system are 336.3 kW, 39.38%, 44.38%, 0.043 USD/kWh, 2.68 years, and 21,540 tons, respectively. Therefore, the system provides a new solution for energy saving and emission reduction of ships.

With the development of smart grids, it has become possible to take demand-side resource utilization into account to improve the comprehensive benefits of combined heat and power microgrids (CHP-MGs). In order to improve the benign interaction between the source and the load of the system, the source side decouples the thermoelectric linkage through energy storage devices and improves the system multi-energy supply capacity by introducing various energy flow forms of energy devices. On the demand side, considering the elasticity of electric heating load and the diversity of heating mode, an integrated demand response (IDR) model is established, and a flexible IDR price compensation mechanism is introduced. On this basis, aiming at the optimal stability of supply and demand and the minimum operating cost of the system, a multi-objective optimal operation model of combined heat and power source–load interaction is constructed, taking into account the user satisfaction with energy consumption and the internal equipment load constraints of the system. Finally, an improved multi-objective optimization algorithm is used to solve the model. The analysis of the algorithm shows that the source–load interaction multi-objective optimal scheduling of the cogeneration microgrid considering the stability of supply and demand can effectively improve the stability of supply and demand and the economy of the system.

Abstract Background Mesoamerican nephropathy (MeN) is a pattern of chronic kidney disease (CKD) prevalent among Central American men who work in agriculture, and its underlying cause has not been elucidated. Currently, experts hypothesize that MeN is related to repeated episodes of occupational heat stress leading to water loss and hence it is also called dehydration-associated CKD. Case presentation We report a case of a 40-year-old man, whose first admission to Peking Union Medical College Hospital was due to acute kidney injury (AKI). The clinical and pathological processes were consistent with acute tubular necrosis (ATN). However, after full recovery, CKD developed 1 year later. The second renal biopsy showed characteristics of ischemic renal disease but there was no evidence of vascular disease. It is worth noting that the patient had been taking part in long-distance running without drinking adequate water for years, which would have markedly decrease his renal blood flow. Thus, this patient may have developed chronic dehydration-associated kidney disease sharing the similar etiology of MeN. Conclusions We report here a case of dehydration-associated CKD in a Chinese patient which shared similar etiology to MeN. Even in non-agricultural areas, this etiology of CKD should be noted to obtain a relevant history and prompt diagnosis.

The integrated energy system (IES) optimal scheduling under the comprehensive flexible operation mode of pumping storage is considered. This system is conducive to the promotion of the accommodation of wind and solar energy and can meet the water, electricity and heat needs of coastal areas far away from the energy center. In this study, the joint dispatch between double pumped storage power stations is used to accommodate wind and solar energy better and smooth their fluctuations on the grid. Through the scheduling of water between the high and low reservoirs of double pumped storage power stations and the reservoir of the seawater desalination plant, the impact of storage capacity constraints on pumped storage power plants is reduced. Moreover, the objective function to build the IES optimization scheduling model is to achieve minimum economic cost. The results reveal that the integrated energy system accommodates all wind energy and solar energy. As such, the system increases the average working time of the pumped storage unit by 1.9 hours and reduces the economic cost by 31.50%. Based on the simulation results, the model can enhance the accommodation capability of wind energy and solar energy and improve the system economy.

Acquired von Willebrand syndrome (AVWS) is caused by an acquired deficiency of von Willebrand factor (VWF), a multimeric protein required for primary hemostasis. For patients with heart valve diseases, high gradient across the malfunctioning valves could cause elevated shear stress and damage the most effective large VWF, eventually resulting in AVWS. However, AVWS has not been reported in association with normally functioning mechanical valves. Herein, we reported a 74-year-old female who suffered from recurrent gastrointestinal bleeding with a history of mechanical aortic and mitral valve replacement. This patient’s function/antigen ratio of VWF was decreased and gel electrophoresis revealed the loss of large VWF, which confirmed the diagnosis of AVWS. Echocardiogram showed that the function of the prostheses was normal. However, the gradient across aortic valve was increased due to a high cardiac state which is secondary to chronic anemia, resulting in the disruption of large VWF multimers and exacerbation of gastrointestinal (GI) bleeding. After managing the patient’s anemia with transfusion, the gradient across the aortic valve had improved, with the resolution of GI bleeding. This is the first case report of AVWS that is associated with a normally functioning mechanical valve. AVWS should be considered one of the differential diagnoses if patients present with unexplained GI bleeding on the background of having prosthetic heart valves. The management of the underlying condition is essential.

Transition metal catalysts are particularly effective in improving the kinetics of the reversible hydrogen storage reaction for light metal hydrides. Herein, K2MoO4 microrods were prepared using a simple evaporative crystallization method, and it was confirmed that the kinetic properties of magnesium hydride could be adjusted by doping cubic K2MoO4 into MgH2. Its unique cubic structure forms new species in the process of hydrogen absorption and desorption, which shows excellent catalytic activity in the process of hydrogen storage in MgH2. The dissociation and adsorption time of hydrogen is related to the amount of K2MoO4. Generally speaking, the more K2MoO4, the faster the kinetic performance and the shorter the time used. According to the experimental results, the initial dehydrogenation temperature of MgH2 + 10 wt% K2MoO4 composite is 250 °C, which is about 110 °C lower than that of As-received MgH2. At 320 °C, almost all dehydrogenation was completed within 11 min. In the temperature rise hydrogen absorption test, the composite system can start to absorb hydrogen at about 70 °C. At 200 °C and 3 MPa hydrogen pressure, 5.5 wt% H2 can be absorbed within 20 min. In addition, the activation energy of hydrogen absorption and dehydrogenation of the composite system decreased by 14.8 kJ/mol and 26.54 kJ/mol, respectively, compared to pure MgH2. In the cycle-stability test of the composite system, the hydrogen storage capacity of MgH2 can still reach more than 92% after the end of the 10th cycle, and the hydrogen storage capacity only decreases by about 0.49 wt%. The synergistic effect among the new species MgO, MgMo2O7, and KH generated in situ during the reaction may help to enhance the absorption and dissociation of H2 on the Mg/MgH2 surface and improve the kinetics of MgH2 for absorption and dehydrogenation.

Waste cooking oil (WCO) is a promising feedstock for producing biodiesel, which plays a significant role in waste resource reusing and renewable energy production. It is known that cost is the main factor restricting the large-scale production of biodiesel. Therefore, the Life Cycle Cost (LCC) method was used to analyze the economic feasibility of the biodiesel production process from WCO. Our results show that the cost of producing 1 ​t of WCO biodiesel is 6291.56 RMB, which is 65.28% higher than the cost of diesel. The factors influencing WCO biodiesel production cost was further analyzed. Although WCO has a low commercial price, necessary pretreatment is inevitable and creates additional processing cost, since WCO cannot be directly used for transesterification to produce biodiesel. The cost of pretreatment process is relatively high, accounting for 15.60% of the total cost. Special waste management policy should be implemented and waste cooking oil recycling technology should be advanced, in order to make WCO biodiesel more economically competitive. Aspen Plus software was used to simulate the production process of biodiesel from WCO, and the production process was simulated by a two-step method. The practicability of simulation was confirmed by purity of biodiesel reaching 99.6 ​wt%. In the simulation, processing parameters of methanol rectification tower and biodiesel rectification tower were optimized to provide a reliable benchmark for the industrial biodiesel production from WCO.

Introduction Accelerated atherosclerosis is a major complication of systemic lupus erythematosus (SLE), and it leads to increased cardiovascular morbidity and mortality in patients with SLE. This study aimed to investigate the natural progression of carotid intima-media thickness (CIMT), and to examine the risk factors for progression of CIMT and atherosclerotic plaques based on a Chinese SLE cohort.Methods and analysis Participants were continuously enrolled as outpatients of the Department of Rheumatology in Peking Union Medical College Hospital (PUMCH) from October 2013 to December 2016. Inclusion criteria were as follows: (1) age ≥18 years, (2) fulfilment of clinical classification criteria of SLE and (3) provision of signed written informed consent. Patients with clinically overt coronary artery disease, a history of cardiovascular disease (previous stroke, heart failure, myocardial infarction, angina or symptomatic peripheral artery disease) and malignancy, and pregnant/lactating women were excluded. The primary outcome is progression of CIMT from baseline. A total of 440 patients with SLE will be enrolled. Participants will receive follow-up surveys ~5 years after their baseline visit. A standard structural survey form, including demographic data, medical history, clinical and laboratory assessments and CIMT measurement, is planned for data collection at baseline and follow-up. The risk prediction model for progression of CIMT will be created by using a mixed effect model.Ethics and dissemination The study protocol was approved by the institutional review board of PUMCH (S-599). Informed consent was obtained from all participants according to the Declaration of Helsinki on Biomedical Research Involving Human Studies. All data will be managed confidentially according to guidelines and legislation. Dissemination will include publication of scientific papers and/or presentations of the study findings at international conferences.

In this study, some of the optimal parameters for a new-style marine axial flow fan are defined by using numerical simulation and experimental tests with a large marine axial flow fan, based on the analysis of the blade perforation’s influences on its internal flow field and aerodynamic noise characteristics. Test result shows that the noise reduction for the axial flow fan with perforated blade is about 3 dB when the blade perforation diameter D is 10 mm and its deflection angle α is 45°. The results of the study show that there is an inhibitory effect on the discrete noise of axial flow fan with perforated blade on the tip area, and its total noise level emerged as the fluctuated distribution characteristics with the increase in the perforation diameter D and reduced along with the increase in the deflection of perforation angle α, at the same time varied as a linear characteristics, which can be reasonably explained by the acoustic interference theory. The results of the study have also further confirmed that the improvement of the flow of axial flow fan with perforated blade helps to reduce the pressure pulsation amplitude caused by the turbulence of the blade surface boundary layer, thereby suppressing the back-flow and vortex from the pressure surface to the suction surface efficiently. It is indicated that the improved vortex shedding phenomenon at the blade trailing edge after perforation on the area of blade tip is the main reason for the aerodynamic noise reduction of axial flow fan.