Search

The treatment of tritiated water(HTO) produced during the operation of nuclear power plants involves the challenging process of H2O/HTO separation, for which non-radioactive H2O/HDO separation is usually used as a research model in laboratories. Recently, membrane distillation processes based on multi-layered graphene oxide membranes showed good performance for H2O/HDO separation, but further improvement still need developing novel membrane materials or structures. In view of this, mono-layered graphene oxide nanoplatelets with different lateral sizes were utilized to prepare PTFE supported graphene oxide composite membranes for H2O/HDO separation in membrane distillation:(1) two types of mono-layered graphene oxide nanoplatelets with different lateral sizes were chosen to investigate the impact of lateral size of mono-layered graphene oxide nanoplatelets on the performance of H2O/HDO separation. The graphene oxide membrane based on GO nanoplatelets with the smaller lateral size gives the permeation flux of 0.944 L/(m2·h) and the separation factor of 1.043, and its overall separation performance is higher than that of graphene oxide membrane obtained with the larger lateral size of graphene oxide nanoplatelets; (2) mono-layered graphene oxide nanoplatelets with different lateral sizes were mixed in various mass ratios for the combination of their structural characteristics to prepare composite membranes. When the mixing mass ratio of the two sizes of graphene oxide nanoplatelets is 1:1, the resultant graphene oxide membrane exhibits permeation flux of 0.806 L/(m2·h), higher than that of the graphene oxide membrane prepared with the larger lateral size, and the separation factor of these two membranes is similar; (3) mono-layered graphene oxide nanoplatelets with the larger lateral size were etched to introduce in-plane pores. The resulted GO membrane gave enhanced H2O/HDO separation performance. These results demonstrate that the lateral size of mono-layered graphene oxide nanoplatelets can affect the performance of corresponding membranes for the separation of H2O/HDO in membrane distillation, and the membranes based on mono-layered graphene oxide nanoplatelets with smaller lateral size or mono-layered graphene oxide nanoplatelets with different lateral sizes mixed in a certain ratio has better performance for the separation of H2O/HDO in membrane distillation. Moreover, the separation performance of H2O/HDO in membrane distillation can also be improved by introducing in-plane pores to graphene oxide nanoplatelets. Therefore, this work can guide the development of novel membrane materials or structures to achieve better H2O/HDO separation performance in membrane distillation and provide solutions for the treatment of radioactive wastewater containing tritiated water.

The insulation performance of transformer bushings is a crucial aspect that directly affects the safe operation of equipment. To diagnose the insulation status of transformer bushings and mitigate the impact of small-sample imbalanced data on diagnostic results, a particle swarm optimization combined with back propagation neural network (PSO-BPNN) and adaptive synthetic sampling (ADASYN) method are employed to fault diagnosis of transformer bushing. Initially, historical fault data of transformer bushings are gathered, and a sample set of dissolved gases in transformer oil with distinct fault categories is established. The ADASYN algorithm is used to synthesize the minority class samples in the original data, which allowed for obtaining balanced fault data. The balanced dissolved gases in oil served as the model input, and the fault status is used as the label output to diagnose the transformer bushings using the PSO-BPNN model. To diagnose the bushings under the original sample set, the back propagation neural network (BPNN), genetic combined with back propagation neural network (G-BPNN), cuckoo search combined with back propagation neural network (CS-BPNN), and PSO-BPNN models are used. The results reveal that the PSO-BPNN model based on ADASYN balanced data exhibited the highest accuracy among the various models for fault diagnosing the insulation status of transformer bushings. This approach effectively mitigate the impact of small sample imbalanced data on diagnostic results, and provide an effective method for assessing the insulation performance of transformer bushings.

Maintaining long-term stability of patient's condition is crucial in the treatment for bipolar disorder， while accurately assessing the patient's disease status is important and challenging in maintaining treatment. Excessive status expectation is common in patients with bipolar depression， which would warp the patient's perception of his or her own disease status and， thus， ultimately interfere with clinical decisions. Heightened vigilance should be given to such phenomenon. This paper explores the phenomenon and potential mechanisms of excessive status expectation in patients with bipolar disorder， providing ideas for related diagnosis， treatment and research. ［Funded by Jiangsu Provincial Science and Technology Project （number， BE2015609）］

In order to further investigate the dosing scheme for circulating water in the steel industry，the spatial and temporal distribution of different water quality types was analyzed using principal component analysis. Moreover， the scaling index method was used to analyse the tendency of scaling in five regions under different water quality types and different concentration multiples to determine the dosing scheme. The principal component analysis showed that：groundwater was mainly affected by calcium hardness，conductivity，total alkali and chloride ions，while river water or municipal water was mainly affected by total iron and turbidity；the scaling index method shows that：groundwater was scaling for supplementary water，while river water or municipal water was corrosive for supplementary water；it was recommended that the concentration factor was 4-5 when groundwater was supplementary water，and 3-4 when river water or municipal water was supplementary water. Based on the type of water quality and the concentration factor in each area，the recommended dosing plan for each area is optimized.

Marine litter pollution is one of the top ten global environmental problems and a common environmental challenge faced by the world, and it is currently a priority environmental issue for the government of China. Based on the perspective of new economic sociology, this paper used the micro data obtained from field research in Qingdao City to build a multi-dimensional analysis framework of the public's willingness of marine litter management. The empirical results showed that the public in Qingdao City had a basic level of cognition of marine litter pollution and an urgent need for management. 70.28% of respondents were willing to support marine litter management. In participating in the management of marine litter, the public not only had the characteristics of "economic people", but also had the characteristics of "social people". Government governance, pollution awareness, social culture, and relationship networks all had a significant positive impact on the public's willingness of marine litter management, and individual social, economic, residential characteristics and other independent factors also had a significant impact.

BackgroundThe neutron scintillator detector is one of the main detectors for China Spallation Neutron Source (CSNS). High detection efficiency is the design goal of the second-generation neutron scintillator detector, which is in process of development, composed of neutron scintillation screen, wavelength transfer optical fiber and photoelectric converter. CSNS_VASD chip is an application-specific integrated circuit (ASIC) developed for China Spallation Neutron Source as the second-generation neutron scintillator detector.PurposeThis study aims to evaluate the performance of the front-end ASIC chip CSNS_VASD by experimental test.MethodsThe combined architecture of "ASIC test board plus digital readout board" was adopted for overall test system design. The ASIC test board was used to amplify, shape and distinguish signals whilst the digital readout board took the roles of configuring the ASIC and its auxiliary circuits, packing and caching the test data, and sending it to the back end for processing and analysis through optical fiber Ethernet. The relevant performance parameters of the chip were tested in the laboratory using exponential like wave test signal with amplitude of 10~120 MV, pulse width of 1 μs and frequency of 100 K as the input signal of ASIC chip, and the neutron beamline of CSNS.ResultsThe results show that the nonlinear error of CSNS_VASD is better than 1%, the equivalent voltage noise is better than 0.63 mV, the crosstalk value is better than 0.89%, and the detection efficiency of the detector is 40.7%@0.1 nm.ConclusionsAll of the test indexes meet the requirement of the design target. The successful development of the CSNS_VASD chip provides a reliable technical guarantee for the smooth construction of China Spallation Neutron Source.

Objective To introduce the Hr gene of spontaneously mutated SHJHhr mice into BALB/cAShjh inbred mice with clear genetic background,and provide a basis for study on the molecular mechanism of Hr gene mutation-induced abnormal phenotype and the application of this model. Methods Using a backcross-intercross breeding method guided by phenotypic monitoring, mutant genes from SHJHhr mice bred by spontaneous mutation were introduced into inbred BALB/cAShjh mice by homozygous mutation introgression, and the mice were bred into BALB/cA.Cg.SHJHhr (abbreviated as C.Cg.SHJHhr) mice after 10 generations. The genotypes of 90 single nucleotide polymorphism (SNP) detection sites were analyzed in C.Cg.SHJHhr mice by multiplex PCR library construction followed by next generation sequencing. Then 14 biochemical locus marker genes were detected in C.Cg.SHJHhr mice according to the method of GB/T 14927.1-2008. Finally, whole genome exon sequencing was utilized to detect the mutated genes in this mouse.Results From May 2018 to March 2022, a total of 10 generations of backcross-intercross were conducted to complete the construction of the C.Cg.SHJHhr mouse line. Among the 90 SNPs loci detected, except for rs13484115 and rs13484116, all the other loci had the same genotype as the recipient mice BALB/cAShjh. The results of biochemical marker gene detection showed that all the 14 loci of the mouse were the same as those of the recipient mouse. Whole genome exon sequencing found that the mouse had 109 site mutations compared with the recipient mouse strain, including 71 synonymous mutations, 1 stopgain, 37 missense mutations, and 20 genes involved in protein sequence alterations (including the reported Hr gene).Conclusion C.Cg.SHJHhr mice were created. Through exon sequencing and genetic analysis, three Hr mutated genes and associated mutated genes that mainly cause phenotypic variations were identified, which provides a basis for expanding the application of C.Cg.SHJHhr mice in biomedical research.

Objective To explore the regulative effect of α-Hederin on the proliferation and invasion of NSCLC and investigate its related molecular mechanism. Methods After A549 and HCC-1833 cells were treated with a concentration gradient of α-Hederin for 24 and 48 h, the OD450nm was detected by using CCK8 assays, and the IC50 was calculated.The A549 and HCC-1833 cells were divided into the blank control and α-Hederin groups in accordance with IC50 values.Cell proliferation was detected by EdU assays, and cell cycle transformation and cell apoptosis were detected by flow cytometry.Cell mobility was detected by using Transwell and scratch assays.SREBP1 and FASN protein expression levels were detected through Western blot analysis, and cell lipid accumulation was detected via oil red O staining. Results The survival rate of lung cancer cells decreased significantly with the increase of α-Hederin concentration, and the IC50 values of A549 and HCC-1833 cells at 48 h were 15 and 25 μg/ml, respectively.Compared with the blank control group, cells proliferation and migration were significantly inhibited, cells were blocked in the G1/S phase, the apoptosis rate increased, and the protein expression and lipid accumulation of SREBP1/FASN significantly reduced after α-Hederin treatment. Conclusion α-Hederin can inhibit the proliferation and migration, G1/S phase transition and induce the apoptosis of NSCLC cells and hinder the malignant progression of NSCLC by downregulating the expression of SREBP1 and FASN and reducing the accumulation of cell lipids.

ObjectiveTo develop a determination method for streptomycin and dihydrostreptomycin in cheese using high performance liquid chromatography-tandem mass spectrometry.MethodsThe samples were extracted with 20 mmol/L Na2HPO4 solution （pH 7.4， adjusted by 6 mol/L HCl） through sonication. The purification and enrichment were carried out by a WCX mixed-mode weak cation-exchange SPE column. The samples were separated by UPLC， ionized by electrospray ionization triple quadrupole mass spectrometer and detected under selected reaction monitoring mode.ResultsThe linear range was 1-200 ng/mL with correlation coefficients （r） higher than 0.996. The spiked recoveries ranged from 82.2% to 116.2% with relative standard deviations of 2.67%-7.2%. The limits of detection of streptomycin and dihydrostreptomycin were both 5 µg/kg and the limits of quantitation were both 10 µg/kg.ConclusionThis method is rapid， simple， highly sensitive and suitable for the detection of streptomycin and dihydrostreptomycin in cheese.

Water ramjet is the most ideal power propulsion device for high-speed underwater weapons. However, failure to start it at low-speed makes it hard for the engine to be widely used. In order to solve the problem of starting water ramjet at low-speed, a configuration scheme of water ramjet pressurized water intake system of the micro-turbine driving micro-mixed-flow pump is proposed. The design method of micro-turbine and micro-mixed-flow pump is perfected. And the simulation model of turbine and mixed-flow pump is established. The rationality of the design results was verified by numerical simulation. The matching design of the turbine and the mixed-flow pump is completed. And the working performance of the pressurized water inlet system is analyzed. The results show that the maximum relative deviation between the design results of the turbine and the pump and the target value is less than 3.2%, and the booster system can increase the fluid pressure by 2.0 MPa, reducing the starting speed of the ramjet from 90 to 63 m/s. The research results of this paper have reference value for the engineering application of water ramjet technology.

ObjectiveAn ultra-high performance liquid chromatography-tandem mass spectrometric （UPLC-MS/MS） method was developed to quantitatively determine the six kinds of aflatoxins in dairy products by employing a novel graphene based adsorbent.MethodsThe samples were dissolved in water and extracted by acetonitrile. After concentrated with nitrogen， the extracts were re-dissolved in the mixture of acetonitrile and 0.1% formic acid （1∶1）， and purified by graphene adsorbent. The analytes were separated by UPLC， and detected with triple quadrupole mass spectrometer.ResultsThe linear range was 0.05-100 ng/mL with correlation coefficients （r） above 0.998. The recoveries of aflatoxins in spiked dairy product ranged from 91.0% to 118.5% with relative standard deviations of 2.39%-6.00%. The limits of quantitation were in the range of 0.01-0.05 μg/kg.ConclusionThis simple and sensitive method can be used for rapid determination of six kinds of aflatoxins in dairy products.

Given the practical issues of the traditional power system's insufficient operational flexibility in the face of changing residential power load and source-side output, demand response can effectively improve the flexibility, safety and economic benefits of system operation. The value of demand response is especially noticeable meanwhile the refined assessment of demand response potential is an important basic support. A method is proposed about evaluating aggregate demand response potential in the absence of historical demand response data based on Gaussian mixture model. Firstly, the typical data are selected through two-stage clustering of households and similar days to improve data representativeness. Then the Gaussian mixture model is introduced to accurately explore the probability distribution of household electricity consumption behavior and calculate individual households' demand response potential. Finally, the bottom-up weighted aggregation is implemented to evaluate the aggregate demand response potential under multiple confidence scenarios. According to empirical analysis, this method can mine hourly information of residential demand response potential from historical electricity consumption data, which can reflect the distribution of power load and demand response potential. Comparative analysis is used to validate the validity of typical data selection by two-stage clustering.

The large-acceleration motion of HFV (hypersonic flight vehicle), the high-speed rolling of spinning missile, and the large-maneuver flight of fighter aircraft has put forward higher performance demand for SINS (strapdown inertial navigation system). The high-accuracy positing will be realized under the high-dynamic maneuver environment after decreasing measurement error of IMU (inertial measurement unit), meanwhile the algorithm of SINS must be improved. The conventional algorithm calculates the flight attitude with determining the compensation term of coning error, after ignoring the high-order term of the Bortz equation. To improve the algorithm accuracy of SINS under high-dynamic maneuver environment, a high-accuracy algorithm, which uses Legendre polynomial to complete angular velocity function approximation and takes the numerical method of quaternion differential equation as core, is proposed herein. The high-order coning error is compensated in the numerical solving period in the proposed novel algorithm, because no approximation exists in deducing process. The attitude calculating simulations are finished in coning motion condition and high-dynamic maneuver condition respectively. Compared with the quadruple-cross-product compensation algorithm which has the highest accuracy at present, the attitude error of proposed algorithm is less than its 1/3 in coning motion condition. And algorithm accuracy is raised an order of magnitude under the high-dynamic maneuver environment. The high-accuracy algorithm based on Legendre polynomial has reference significance for accurate positing of future HFV, atomic gyroscope INS research and high-accuracy algorithm design of SINS.

In the process of deep coal seam mining, confined water pressure and complex structural environment are important factors threatening mine safety production. In order to study the water inrush law of floor under the influence of fault on confined water, based on the basic mechanical principle, the mechanical model of surrounding rock under the influence of coal seam mining on confined water is established to solve the critical water pressure of fault water inrush. At the same time, based on the control variable method and fluid solid coupling theory, using FLAC3D numerical simulation software, from the perspective of the joint coupling of stress field, displacement field, seepage field and failure area, the water inrush law of coal seam floor under different fault shape and confined water pressure is analyzed. The results show that when the working face is mined near the fault area, the fault dip angle has a great influence on the vertical stress on the surrounding rock. When the dip angle changes from 30° to 60°, the average change rate of the vertical stress is about -29%; the fault width mainly affects the damage degree of the fault near the bottom of the working face. The wider the fault width, the smaller the damage degree; the aquifer water pressure plays a leading role in the pore water pressure in the fault. The greater the dip angle and the smaller the width of the fault, the higher the pressure of confined water in the aquifer, and the stronger the risk of water inrush in the floor.

BackgroundThe in-vessel retention (IVR) strategy is an important measure for mitigating severe reactor accidents. It has been successfully applied to the severe-accident management of advanced pressurized water reactors such as the AP1000, HPR1000, and CAP1400. In the implementation of the IVR strategy, the lower head is deformed by the heat load of the high-temperature melt. This affects the heat-removal capacity of the pressure-vessel external cooling and the successful implementation of the IVR strategy. It is necessary to examine the stress, failure, and deformation of the lower head.PurposeThis study aims to develop a large deformation model for the pressure-vessel lower head and analysis of its application in the FOREVER experiment.MethodsA mechanistic model called the lower-head large-deformation model was developed to address the limitations of the simplified film stress model of the Integrated Severe Accident Analysis (ISAA) program Lower Head Thermal Creep Module (LHTCM), which is very simple, and the absence of a deformation calculation module in the LHTCM model. This model was based on Timoshenko plate and shell theory, the Norton creep law, and large-deformation plasticity theory. Then, the model was integrated into the ISAA program to calculate the FOREVER-EC2 experiment.ResultsThe overall deformation result predicted by the large-deformation model exhibits the characteristic egg-like shape, with maximum displacement occurring at the bottom position of the lower head. The failure time predicted by the large-deformation model is 394.33 min, with an error of only 1.9% relative to the experiment. The predicted bottom elongation is consistent with the experimentally measured value. Additionally, the predicted location of the breach is consistent with the experiment, occurring between 75º and 85°.ConclusionsThe lower-head large-deformation model of this study can accurately predict the stress, failure time, overall deformation, and location of the breach of the lower head in a severe core melting accident.

BackgroundThe Energy Resolved Neutron Imaging Spectrometer (ERNI) of China Spallation Neutron Source (CSNS) is in process of building, whose diffraction detector with ninety degree partition adopts 6LiF/ZnS neutron scintillator detector with a 90° partition as its detection equipment.PurposeThis study aims to develop the readout electronics for high position resolution neutron scintillator detector of ERNI.MethodsFirstly, a capacitive network combined with center-of-gravity of the induced charge distribution was adopted for the design of readout electronics. Then, a prototype of the readout electronics system consisted of three parts: capacitive network circuit, preamplifier board and digital readout board, was developed. After functional verification, the relevant performance parameters of the developed prototype were experimentally tested in the laboratory and in the No.20 beam line of CSNS.ResultsThe experimental results show that the integration nonlinearity of electronics is better than 0.95%, the time resolution is about 12 ns, the position resolution is 1mm, and the detection efficiency is 65%@1.6 Å.ConclusionsThe prototype meets the design specifications of the project. The successful development of the prototype provides a reliable technical support for the smooth development of the spectrometer experiment in ERNI of CSNS in the future.

The inhibitory effects of ClO2, clove essential oil and cinnamon essential oil on Fusarium graminearum were studied by observing the colony diameter, mycelial growth and spore germination. The results showed that ClO2, clove essential oil and cinnamon essential oil had significant inhibitory effect on Fusarium graminearum, among which, clove essential oil had lower inhibitory effect than cinnamon essential at low density (20~40 µL/L air), and its inhibitory effect was improved dramatically and better than cinnamon essential with the increase of density. Through the regression equation of inhibition rate, the IC50 of ClO2, clove essential oil and cinnamon essential oil were 27 mg/L, 58 µL/L air and 66 µL/L air respectively. By means of ergosterol content determination, scanning electron microscope observation and Fourier transform infrared analysis, we found that ClO2 and essential oil destroyed cell structure in different degrees, ClO2 destroyed cell membrane, leading to the exudation of contents. High density of clove essential oil destroyed cell structure, while cinnamon essential oil resulted in maldevelopment of mycelium.

Aiming to solve the problems of low cache hit rate and high average routing hops in the traditional cache strategies of named data networking (NDN), a cache optimization strategy for improving cache hit ratio is proposed. For each routing node, the dynamic priority value of each content block was calculated by combining the hit times of the current cached content block and the hit time characteristics of the request. The cached content block was then replaced according to this value to retain the content block with high current request rate and expected high future request rate. On this basis, according to the average priority value of each routing node on the content request path, a high priority cache decision strategy was designed to select a reasonable cache placement node. A large number of simulation results show that compared with the typical NDN cache strategy, this strategy can effectively improve the cache hit rate and reduce the average request hops.

Objective To investigate the impact of lymph node metastasis on the survival of SCLC patients with M1a disease. Methods We retrospectively analyzed the medical records of 7027 SCLC patients with M1a disease from 2004 to 2015 in SEER database. The Kaplan-Meier method and log-rank test were used to estimate the OS in all N stage subgroups. Cox proportional hazard model was used to assess whether N stage was an independent risk factor for prognosis. Results The median OS of all patients was 7 months. Among all M1a patients, the patients without lymph node involvement (N0) had the best OS, followed by N1 stage patients; N2 and N3 stage patients had the worst OS (P < 0.001). Similarly, this trend was observed when M1a disease was subdivided into contralateral pulmonary nodules, malignant pleural effusion and malignant pericardial effusion. Multivariate analysis showed that lymph node metastasis was an independent prognostic factor for SCLC patients with M1a disease, and this result was also noticed in all subgroups of M1a disease. Conclusion Lymph node metastasis may affect the survival of SCLC patients with M1a disease, adding prognostic information. And it is recommended to further improve the N descriptor in the next version of TNM staging system.

The effect of silica modified by silane coupling agent （TESPT） and deep eutectic solvent （DES） on the properties of natural rubber （NR） composites as tread rubber was studied. The interaction between TESPT, DES and silica was analyzed by Fourier transform infrared spectroscopy, the interaction between silica and silica was analyzed by rubber processing analyzer and scanning electron microscope, the curing characteristics, mechanical properties and wear resistance of the composites were determined, and the rolling resistance and wet skid resistance were investigated by dynamic mechanical analyzer. The results showed that the synergistic modification of TESPT and DES could improve the dispersion of silica in NR, increase the vulcanization rate, improve the mechanical properties and wear resistance of the composites, and reduce the rolling resistance. When the amounts of TESPT and DES were 1 phr （mass） respectively, the NR composites had lower rolling resistance and better wet skid resistance.

Objective To explore the incidence of pain flare (PF) in spine metastasis stereotactic body radiotherapy (SBRT) or hypofractionated radiotherapy (HF) and the prophylactical effect of dexamethasone. Methods Sixty-five patients were treated with spine metastasis SBRT and randomly divided into control group (SBRT or HF, n=32) and treatment group (SBRT or HF and 4.5 mg dexamethasone, n=33). The brief pain inventory (BPI) was used to score the pain before, during and after treatment. PF was recorded and compared between two groups. Results The incidence of PF was 24.6% in all patients (control group: 37.5%, treatment group: 12.1%, P=0.018). PF in both group occurred in d1-2, accounting for 62.5% in all PF (control group: 66.7%, treatment group: 50%, P=0.551). The incidences of PF in control group were 66.7% and 33.3% for three and ten fractions scheme, respectively (P=0.001). However, the incidences of PF in treatment group were 50% and 50% for three and ten fractions scheme, respectively (P=0.643). Conclusion Oral dexamethasone has an excellent efficacy in prevention and treatment of PF in spine metastasis SBRT or HF, with significantly decreased incidence of PF. A phase Ⅲ clinical trial is required to finalize the optimal dose and schedule.

BackgroundIn a pressurized water reactor (PWR) loss-of-coolant accident (LOCA), high temperature and high internal pressure of the fuel rod can lead to ballooning of fuel rod cladding, which causes a partial blockage of flow area in a subchannel. Such flow blockage would influence the core coolant flow and thus affect the core heat transfer during reflood phase and subsequent severe accidents. However, the commonly used integrated severe accident analysis codes use simple parametric models to simulate these aspects and therefore cannot consider the influence of multiple coupled factors. This results in a lack of accuracy of the simulation results.PurposeThis study aims to analyze the key phenomena in core degradation, and develop a thermal-mechanical (TM) behavior module for assessing the failure of cladding and analyzing the flow blockage.MethodsFirst of all, the fuel rod thermal–mechanical behavior (FRTMB) module developed for analyzing the TM behavior of fuel rods was integrated into the integrated severe accident analysis code (ISAA). Then, on the basis of the FRTMB module, the flow blockage model of the ISAA-FRTMB code was improved to suit for simulating changes in coolant flow rate caused by fuel rod deformation. Finally, the QUENCH-LOCA-0 experiment was simulated by using improved ISAA-FRTMB code to verify the correctness and effectiveness of the model, and the peak cladding temperatures were compared in order to verify the validity of the flow blockage model.ResultsThe results including cladding failure time, circumferential strain, flow blockage rate and cladding temperature predicted by the code are in good agreement with the experimental data. The maximum circumferential strain of the simulated cladding, as indicated by the experimental results, is in the range of 25%⁓50%, and the errors of the predicted cladding rupture time and temperature are within 4%.ConclusionUnder the stress caused by internal pressure, the cladding deforms outward owing to thermal creep with the increase of temperature. Rapid thermal creep and swelling lead to cladding failure. The maximum circumferential strain of the simulated cladding, as indicated by the experimental results, is in the range of 25%⁓50%, and the errors of the predicted cladding rupture time and temperature are within 4%. The correctness and effectiveness of FRTMB module are thus verified.

The mechanical behavior of the quenching and partitioning 980 (QP980) steel is affected by martensitic transformation during deformation. The microstructure of QP980 steel before and after deformation is characterized by using the electron backscattered diffraction (EBSD) method. An elastic visco-plastic self-consistent (EVPSC) polycrystalline model considering phase transformation is established based on the phenomenological theory of martensite crystallography (PTMC). The macroscopic flow stress as well as texture evolution of QP980 steel during uniaxial tension process is reproduced by the model. The material consists of ferrite (F), martensite, and retained austenite (RA) with rolling texture in the initial state. After deformation, the content of RA decreases and the fiber of the RA, the fiber of the ferrite and martensite along the tensile direction are enhanced. Phase transformation enhances the strength and work hardening rate but has little effect on the texture evolution. According to the distribution of stress and strain during the calculation of deformation, ferrite and tempered martensite (TM) contribute most to the deformation, and the new martensite (NM) is the most probable nucleation sites of fracture due to its highest average stress.

The application of materials with special wettability is a hot research topic in recent years. It is reported that Bi2O3 coating with hydrophobic modification could achieve the reversible conversion of superhydrophobicity to superhydrophilicity under UV-visible light irradiation and dark storage. Based on this finding, the application of Bi2O3 coating in antibacterial and oil-water separation under different wettability was studied. The results show that superhydrophobic surface exhibits good bacterial anti-adhesion effect against E.coli and S.aureus, while superhydrophilic surface shows selectively antibacterial activity. In terms of oil-water separation, the superhydrophobic surface can block water and allow oil pass through the filter with the separation efficiency more than 93%, while the superhydrophilic surface can block oil and allow water pass through the filter after pre-wetting treatment. Therefore, Bi2O3 coating with reversible wettability can be used as an intelligent antibacterial membrane material for oil-water separation, which has potential application in the field of oil-water separation.

To study the changes in dielectric properties for thermally aged cross-linked polyethylene (XLPE) at different temperatures, the pure thermal and thermal-radiation aging tests are done. Thermal aging is carried at 80℃, 100℃, 135℃ and 155℃, lasting for 100 to 800 hours. The same conditions combined with 100 Gy/h gamma rays are done for thermal-radiation aged samples, and the dielectric spectra are measured from 25 to 200℃. The results show that the activation energy and values of β decrease obviously after the introduction of rays. At the same aging temperature and radiation conditions, electrical conductivity and relaxation peak frequency increase as the increasing aging time, which is a good reflection of dielectric properties during the aging process. Under different temperatures, the deviation in complex permittivity and modulus at lower frequency becomes more distinct compared with the values at a higher frequency. Finally, the dielectric properties under high temperature and low frequency could be a good indicator for the evaluation of XLPE degradation.

Since the 1980s, the Pearl River Delta has undergone rapid development on economic and social fronts. Owing to the impacts of large-scale and intensive human activities, the river discharge and sediment loads entering the Pearl River channel networks along with its morphology have changed drastically, leading to substantial alterations in spatial-temporal tide-river dynamics. Accordingly, the estuarine water surface profile has also experienced stepwise evolution. However, little attention has been paid to the mechanisms underlying water-level profile dynamics. In this study, the characteristics of and factors influencing the spatiotemporal evolution of the water surface profiles and residual water level curvature in the Dongping Channel were systematically explored based on the abrupt change in the Sanshui and Makou hydrological stations' flow diversion ratio in 1993, with the Dongping Channel considered as a case study. The obtained results are useful for setting scientific guidelines for evaluating morphological changes, adjusting flood control strategies, preventing saltwater intrusion, and constructing large-scale water conservancy projects. First, according to the abrupt change in the Sanshui and Makou hydrological stations' diversion ratio at the apex of the Pearl River channel networks, the evolution of the surface water profile dynamics in the Dongping Channel was divided into two phases: the pre-human period (1960-1992) and the post-human period (1993-2016). Subsequently, the dependence of the residual water level slope or tidal damping rate on discharge before and after the abrupt change in diversion ratio was studied using the double accumulation curve method. The residual water level curvature before and after human intervention was used to understand the dynamics of the residual water level slope and the resulting water surface profiles; in particular, the larger the curvature, the faster was the change in the residual water level. Meanwhile, the change in curvature from positive to negative (or vice versa) indicated a change in the shape from concave to convex (or vice versa). The results showed that: 1) The slope of the double cumulative curve of the residual water level slope or the tidal damping rate with regard to the river discharge decreased, indicating that the dependence of the residual water level or the tidal damping rate on the river discharge decreased; 2) the water surface slope of the Dongping Channel decreased as a whole, and the water surface slope upper reaches (Zidong-Sanshui reach) decreased the most. The rate of change of the gradient among the four seasons decreased by 4% to 67%. Meanwhile, the curvature fluctuation amplitude decreased, ranging from 2×10-10 to 5.48×10-10 before 1993, and from -0.9×10-10 to -0.07×10-10 after 1993; and 3) the main reason for the substantial change in the water surface profile was that sand excavation occurred in the middle and upper reaches of the Dongping Channel, leading to a substantial deepening of the river bed, a decrease in the water level, and an increase in water discharge. The lower reaches were mainly affected by tidal flat reclamation, resulting in channel deposition. Owing to the geometric changes, both the river discharge and tidal discharge increased in the middle reaches, leading to conversion of the water surface profile into an upward convex shape. Meanwhile, owing to the regulations for the Feilaixia Reservoir in the upper reaches of the Beijiang River and the seasonal regulation for cross-sectional width-depth ratio and sea-level change, the variation in the water surface curvature of the Dongping Channel in winter was much more significant than that in summer.

Objective To observe the clinical effect of tetralogy probiotics combined with galactooligosaccharides on diarrhea in patients after severe craniocerebral injury. Methods A case-control study was conducted on 90 patients with severe craniocerebral injury admitted in the intensive care unit (ICU) of neurological department of our hospital during January to June 2019. They were randomly divided into control and experimental groups, with 45 patients in each group. The patients of the former group was given conventional nutrition therapy, while those of the latter group were treated with conventional nutrition therapy combined with tetralogy probiotics and galactooligosaccharides. After 5 days' enteral nutrition through nasogastric tube, occurrence of diarrhea, ICU duration, indwelling time of gastric tube, and serum levels of total serum protein (TP), albumin (ALB) and prealbumin (PA) were recorded and compared between the 2 groups. Results The experimental group had significantly lower incidence of diarrhea (2.22% vs 17.78%, P < 0.05), and shorter indwelling time of gastric tube (10.04±5.39 vs 14.27±8.14 d, P < 0.01) when compared with the control group. There were no statistical differences in the TP, ALB and PA levels between the 2 groups before nutrition treatment (P>0.05). On the 5th day post nutritional treatment, the PA level of the experimental group was obviously higher than that of the control group (180.50±58.73 vs 169.55±67.85 mg/L, P < 0.01). Conclusion Conventional nutrition therapy combined with tetralogy probiotics and galactooligosaccharides can effectively prevent diarrhea in patients after severe craniocerebral injury, improve their nutritional status and shorten the indwelling time of gastric tube.

Active radar remote sensing technology, with its capability of acquiring all-weather data, has great potential for agricultural monitoring. This technology can penetrate vegetation cover more deeply than optical sensors and has sensitivity to the shapes, structures, and dielectric constants of vegetation scatterers. In this paper, we discuss the applications of radar remote sensing in crop identification, cropland soil moisture inversion, crop growth parameter inversion, crop phenology retrieval, agricultural disaster monitoring, and crop yield estimation. We review several specific papers focusing these fields, and then describe the results obtained using information extracted from radar scatterometers and Synthetic Aperture Radar (SAR). Extracted SAR data include characterizations of backscattering, polarimetry, interferometry, and tomography. Lastly, we summarize the problems faced by radar applications in agriculture and consider the future trend of these applications.

Oversampling method is one of the effective ways to deal with imbalance classification problems. This paper focuses on the problems of reducing sampling result faced by the oversampling methods based on SMOTE(synthetic minority oversampling technique) in the occurrence of class-overlapping and small-disjuncts in dataset. An oversampling method MOLAD based on the local area density is proposed. Furthermore, a method LADBMOTE which combines the MOLAD and Bagging-based ensemble learning in sampling stage is proposed in order to solve the classification problem for imbalanced dataset. LADBMOTE first calculates the [K] nearest neighbors of each minority class sample according to MOLAD, and then selects all [K] nearest neighbors for sampling, thus [K] balanced datasets will be generated. Then, the Bagging-based ensemble learning is used to ensemble classifiers obtained from training [K] balanced datasets. The proposed method LADBMOTE is compared with 7 currently popular algorithms for handling imbalanced data by employing 20 imbalanced datasets published on KEEL. The experimental results show that the classification performance of LADBMOTE on different classifiers is better and more robust.

BackgroundIn the event of a reactor severe accident, in-vessel retention (IVR) is a very effective and important severe accident mitigation measure. The lower head of the reactor pressure vessel (RPV) plays an important role in IVR strategy. The lower head is in a high-temperature environment, and its main failure form is creep failure. Once the lower head fails, it may lead to the release of radioactive substances into the environment.PurposeThis study aims to develop a thermal creep model for reactor pressure vessel lower head to ensure the successful implementation of IVR strategy and prevent radioactive material leakage, and apply this model to OECD lower head failure (OLHF) experiment analysis.MethodsThe thin shell theory and Norton-Bailey creep equation were employed to develop the lower head thermal creep module (LHTCM) model, and four failure criteria were used to evaluate the integrity of the lower head. Then, the LHTCM model was integrated into the integrated severe accident analysis program ISAA to verify and calculate the OLHF experimental data.ResultsThrough the analysis of four failure criteria in LHTCM model , it is found that the relative error between the failure time of the lower head predicted by the LHTCM model using the Larson Miller criterion and the experimental data is within 2.0%, and its predicted the elongation at the bottom of the lower head is more consistent with the experimental data than the other three criteria such as Kachanov criterion.ConclusionsLHTCM model developed in this study can accurately predict the creep behaviour of the lower head, and the calculated failure time, position and bottom elongation of the lower head are in good agreement with the experimental results.

In view of problem that industrial Ethernet switch has higher requirement to quality of power supply, a constant supply system for industrial Ethernet switch was designed. Hardware circuits of the system were introduced in details, namely DC stable voltage supply circuit, charging management and control circuit of battery, temperature detection circuit of battery, switching circuit of power supply, CAN bus communication circuit and single-chip microcomputer control circuit, and main program flow of the system was gave. The test result showed that the system can meet with supply requirements of industrial Ethernet switch under complex environment with characteristics of quick dynamic response, low static power consumption.

Streptomyces albulus is the principal strain for the industrial production of ε-polylysine. Traditional breeding approaches that rely on mutagenesis and resistance screening have been employed to enhance the ε-polylysine yield of S.albulus. Nevertheless, the diminishing returns often seen with these traditional methods have become a significant hindrance to progress in breeding techniques. As a result, the application of metabolic engineering strategies has become imperative to augment ε-polylysine production in S.albulus. In this light, this study have developed a CRISPR-Cas9-based gene editing platform. With S.albulus GS114 as the research object and the ε-polylysine synthase gene pls as the target gene, the pls gene was successfully knocked out in the genome of S.albulus GS114 with a 100% editing efficiency. To further amplify the array of knock-out strains available, this study meticulously refined the conjugation protocol for S.albulus GS114. The optimal conditions identified include a donor-recipient ratio of 1:1, a magnesium ion concentration of 30 mmol/L, an incubation of heat-activated spores at 55 °C for 10 minutes, followed by a 20-hour antibiotic coverage post-incubation. Under these optimized conditions, tthe conjugation efficiency reached 2.5 x 10-8 per recipient cell, marking a 78% improvement over the control. This research not only pioneers a pivotal tool for S.albulus metabolic engineering in the future but also offers insightful guidance for constructing CRISPR-Cas systems in other industrial Streptomycetes. [ABSTRACT FROM AUTHOR]

[Objective] Non-pressurized mesh filters are often installed in front of pumps to filter sediments and debris. In this paper, we study the influence of different irrigation water sources and backwash device parameters on hydraulic performance of a new network filter. [Method] The water flow rate in the experiment ranged from 120 to 160 m3/h, and the sediment concentration in the water varied from 0.2 to 0.8 g/L. The backwash varied from 1 to 20 m3/h, and the velocity gradient in the filter box changed from 1 to 4 r/min. A multi factor dispersion analysis method was used to analyze the experimental results. [Result] ① The initial sediment concentration had minimal impact on hydraulic performance of the mesh filter, contributing only 0.010 8 to the overall effect. However, the influence of water flow duration on the initial sediment concentration was significant, exceeding 159%. ② The fourth model provided the best fit for the overall regression analysis, with a residual value of 0.804 4, significantly higher than other models; its coefficient of determination R² was 0.986 1. ③ the optimal performance was achieved when flow rate was 120.198 m3/h, velocity was 1.112 r/min, and self-cleaning flow rate was 19.934 m3/h. The associated a minimum energy loss was 16.024 kPa. [Conclusion] The model we proposed can accurately predict the impact of operation conditions and sediment concentration in the water on the performance of the non-pressurized mesh filters. Selecting optimal operation conditions can minimize the energy loss across the filter. [ABSTRACT FROM AUTHOR]

With the rapid development of information technology and the widespread use of service computing, effective process man- agement to support on-demand software services has become increasingly important. Modern software service engineering faces many challenges, such as microservice architecture and service splitting, multi-team communication and collaboration. A process management optimization strategy and the algorithm based on DevOps team collaboration and capability maturity model integration (CMMI) is proposed in conjunction with an evolutionary service development methodology based on the agile unified process (ARUP). Case study demonstrates that requirements management and quality assurance are the most effective methods for continuous process improvement in software development, and the proposed algorithm effectively improves the quality, efficiency, and sustainability of software services, providing reference and guidance for academic researchers and industrial practitioners. [ABSTRACT FROM AUTHOR]

[Objective] This paper focuses on the development of a bidirectional consolidated soil sample-making apparatus. The aim is to compare samples made by this apparatus with those created using compaction and static pressure methods and to analyze and verify the feasibility of the bidirectional properties. [Methods] In this paper, three types of test equipment were used to prepare consolidated soil samples of specified age. Several comparative tests were conducted, such as the unconfined compressive strength (UCS) test, the industrial electron microscopy test, the scanning electron microscopy test, and the mercury-in-pressure porosimetry test. These tests helped analyze and verify the feasibility of the bidirectional consolidated soil sample maker. They also enabled us to study the macro/fine/micro characteristics of the samples produced by the three test equipment from various angles, such as UCS and its destructive form, apparent porosity of the sample, microscopic porosity and filling of the curing product, microscopic pore volume, and pore size distribution. [Results] The results show that in terms of macro UCS of consolidated soil samples, the bidirectional sample has the highest UCS, followed by the static pressure sample and then the compaction sample. In terms of sample formation and destruction form, the bidirectional sample is uniform in color and has a stable destruction form (all are shear destruction). The static pressure sample is denser at the top and looser at the bottom, with destruction mostly in the weaker and lower parts. The compaction sample, however, shows distinct layering with varying shades and multiple forms of damage. Thus, the uniformity of the bidirectional sample is superior to that of the compacted and static compaction samples. Upon fine analysis, we found that compared with the static compaction sample (which has an apparent porosity that gradually increases from top to bottom) and the compaction sample (where the apparent porosity gradually decreases from top to bottom), the bidirectional sample has the smallest and most uniformly distributed apparent porosity. At the microscopic level, the bidirectional sample has the highest amount of curing products that can effectively fill the pores, making its internal microstructure the densest. It also has the least amount of mercury intake and is dominated by interparticle pores with smaller diameters. This is followed by the static pressure sample, while the compaction sample has the least amount of curing products, larger pores, the highest amount of mercury intake, and pores mainly distributed in the interparticle pores with larger diameters and the intragranular pores. [Conclusions] Therefore, the multiscale comparative study shows that the self-developed bidirectional sample-making instrument is better than that of the static pressure instrument outperforms both the static pressure and the three-segment mold (or double membrane) in terms of sample making. Not only does it deliver superior results, but it also exhibits a smaller margin of errors in tests. Consequently, this makes it a viable option for widespread adoption and application in geotechnical tests. [ABSTRACT FROM AUTHOR]

The effect of Al and Si elements on the microstructure and properties of Incoloy909 alloy was studied. The results show that the increase in Si element content is conducive to the precipitation of Laves and e phases in the alloy, making the grain distribution in the alloy finer and more uniform, and improving the high-temperature rupture life of the alloy. The increase in Al element content leads to the precipitation of more strengthening phases in the alloy after double aging heat treatment, which enhances the strength and hardness of the alloy. The Al and Si elements fitting has little effect on the average linear expansion coefficient of the alloy. After heat treatment, dislocation density of the alloy decreases, and the strengthening phase disperses and precipitates. The structure is more stable, and the average linear expansion coefficient is reduced. [ABSTRACT FROM AUTHOR]

The present research aims to develop a new kind of green composite curing agent, PZ-1 in which the industrial and agricultural waste such as calcium carbide slag and plant ash are adopted to be raw materials, based on the response surface methodology and unconfined compression strength test results. Then, the mechanism of PZ-1 reinforcement of organic sludge was revealed through SEM and XRD analysis. The test results show that with the increase of calcium carbide slag and plant ash content, the unconfined compressive strength of solidified organic sludge shows a phenomenon of first increasing, then decreasing and continuously increasing, respectively, in which the effect of calcium carbide slag on carbide slag is more significant. The optimal ratio of carbide slag and plant ash in PZ-1 is 20:14. Ca (OH)2 in calcium carbide slag will play the role of neutralizing the humic acid existing in the organic silt and further provide the alkaline environment for the stabilization of PZ-1. The main product of stabilized organic silt is C-S-H gel, calcite, dolomite, ettringite, in which C-S-H gel plays the role of producing the structure of stabilized organic silt and the left 3 minerals behave in filling the pore of silt and further enhancing the density of silt. [ABSTRACT FROM AUTHOR]

An improved fast point feature histogram (FPFH) was proposed for the initial registration of grid point cloud. The neighborhood density was added as a point feature description on the basis of FPFH. When searching the corresponding points with k-dimensional tree (k-d tree), the Bhattacharyya distance was used as the index. This improved method was compared with FPFH in the simulation. Then, the test device was built to collect the grid's surface point cloud data. The data were registered with improved FPFH method and iterative closest point (ICP). Test results show that the precision level of the matched point cloud is 1 µm and the error range of grid hole stays in ±(20~40) µm, which theoretically satisfy the precision requirement of the grid. [ABSTRACT FROM AUTHOR]

In order to reveal the effect of surface roughness on the lubrication performance of marine water lubricated polymer bearings, theoretical research on elastohydrodynamic lubrication of water lubricated bearings was conducted. A hybrid lubrication model of water lubricated bearing considering the roughness and elastic deformation of lining material was established and verified by simulation. The influence of inner liner roughness peak on water film thickness, water film pressure distribution and bearing capacity was analyzed. The results show that the increase of liner roughness will slow down the increase ratio of water film thickness during the increase of rotating speed, so that the bearing needs higher rotating speed to enter the hydrodynamic lubrication state. Reducing the roughness of the bearing lining can effectively reduce the take-off speed of the bearing, accelerate the process of the bearing from mixed lubrication to hydrodynamic lubrication, reduce the local contact between the bearing and the journal, and reduce the possibility of abnormal vibration and noise of the bearing. This research reveals the mechanism of the influence of the change of the inner liner roughness on the lubrication characteristics of the bearing, and provides a theoretical reference for the optimal design of the water lubricated bearing. [ABSTRACT FROM AUTHOR]

In order to achieve the real-time detection of contamination components on the surface of insulators and explore the impact of different insulators on the identification of contamination components, a hyperspectral remote sensing imaging technology based on feature band score evaluation has been proposed. The data of single fouling components for silicone rubber and ceramics has been collected by hyperspectral imaging technology, and the spectral lines are pre-processed using a model of spectral spatial adaptive total variation and a model of fouling component classification and identification based on the maximum correlation of spectral line features, which was established by a maximum correlation-minimum redundancy-back propagation neural network. The spectral spatially adaptive total variance model was able to denoise and smooth the hyperspectral curves, and obtain hyperspectral images that built a classification and recognition model. The model of maximum correlation-minimum redundancy-back propagation neural network used the fractional ranking of the spectral feature bands as the basis for filtering features, and the classification model is high accuracy, up to 92. 5% for contamination components with silicone rubber substrates and 80% for fouling components using ceramic substrates. The classification of contamination components in the hyperspectrum varies between different types of insulators as background substrates, mainly due to the degree of coverage of the fouling layer and the shape of the fouling particles; it is necessary to avoid thin areas of the fouling layer to reduce the background substrate on the detection results. [ABSTRACT FROM AUTHOR]

WPP/WCMWR composites were prepared by extrusion roll forming process using waste polypropylene (WPP) and wormwood Chinese medicine waste residue (WCMWR) as raw materials. The preparation process of WPP/WCMWR composites was optimized by response surface method (RSM). The effects of process conditions such as the screw speed, the calendering pressure and the mass ratio of WPP to WCMWR on the impact strength and static bending strength of composites were studied. The results show that the optimum process conditions are as follows: the screw speed is 71.00 r/min, the calendering pressure is 4.84 MPa, and the mass ratio of WPP to WCMWR is 3:1. The impact strength of WPP /WCMWR composite is 63.60 kJ/m², and the static bending strength is 63.10 MPa. The density of the impact fracture surface of the composites optimized by RSM method is better than that of the composites not optimized by RSM method, and the homogeneity of the materials is enhanced. [ABSTRACT FROM AUTHOR]

Aiming at the problems of low detection accuracy and high missed detection rate of small targets in the mask wearing detection algorithm in complex scenes, a mask wearing detection model based on improved YOLOV5s is proposed. In order to alleviate the problem of information loss caused by continuous downsampling, an inverted adaptive attention module (IAAM) is proposed. In order to improve the sensing ability of high-resolution detection layer to global information, a channel feature grouping module (CFGM) is designed, and the small object detection accuracy is greatly improved by using this module. Combined with the data features in the actual scene, EIoU Loss is introduced, and the color space transformation in data enhancement is cancelled. Experimental results show that the improved model has improved recall rate, detection accuracy, inference speed and detection ability of small targets, and can complete real-time mask wearing detection task in complex scenes. [ABSTRACT FROM AUTHOR]

Objective Huge heat is generated during underground substation transformer operation. Failure to promptly dissipate this heat can lead to problems such as transformer overheating, equipment malfunctions, and even fire accidents. Therefore, it is necessary to study the temperature control of transformer rooms in metro substations. Method Taking the 110 kV underground substation (Qichuan Station) of Jinan Rail Transit Line 3 as example, considering the influence of mechanical exhaust air volume, transformer heat dissipation, and outdoor ambient temperature, theoretical analysis and numerical simulation are conducted to study the temperature control in the transformer room. The temperature evolution law in the main transformer room under 8 different ventilation conditions is analyzed. Result & Conclusion Setting the mechanical exhaust air volume based on theoretical calculations can effectively dissipate the heat generated by the transformer, and the theoretically calculated air volume tends to be conservative. The existing design fans can effectively discharge the heat generated by the transformer, with a maximum capacity to dissipate three times the generated heat. Even under adverse conditions with an outdoor ambient temperature of 40 ℃, the existing design fans can still effectively dissipate the heat generated by the transformer, achieving the temperature control objectives.

Objective With the increasing power supply load required by metro, the operation of oil-immersed equipment such as wet-type transformers under overload conditions is extremely prone to fire, posing a threat to the safety of ceiling structure. To avoid or reduce the possibility of transformer fires, it is necessary to investigate the smoke movement patterns and the variation characteristics of ceiling temperature in main transformer room during fire. Method Taking the 110 kV Qichuan Substation of Jinan Rail Transit Line 3 as example, through theoretical analysis and numerical simulation, considering the comprehensive effects of ventilation conditions, fire heat release rate, and fire source height, the temperature characteristics of smoke below the ceiling in main transformer room during fire are investigated. Result & Conclusion When mechanical ventilation is activated, the organization of indoor airflow will affect the distribution of smoke temperature below the ceiling. Wind replenishment causes the fire plume to deflect, leading to the maximum temperature rise point shifting towards exhaust vents, with the maximum temperature rise slightly lower than when mechanical ventilation is closed. The dimensionless maximum ceiling temperature rise can be divided into two regions: when the flame does not impinge on the ceiling, it exhibits a linear relationship between the dimensionless maximum temperature rise and the ratio of Q2/5 and (hef-h0) (where Q is the fire heat release rate, hef is the distance from fire source surface to the ceiling, h0 is the virtual point source height); when the fire flame impinges on the ceiling, the dimensionless maximum temperature rise is a constant, and a prediction model for the dimensionless maximum temperature rise of the ceiling is proposed. Based on simulation data, prediction models for temperature decrease of ceiling jets driven by weak and strong fire plumes are proposed.