The available test methods for optimal moisture content of cold recycled mixture(CRM)as well as its bulk specific gravity,and theoretical maximum relative density were analyzed in this work.Some test improvements were...The available test methods for optimal moisture content of cold recycled mixture(CRM)as well as its bulk specific gravity,and theoretical maximum relative density were analyzed in this work.Some test improvements were suggested to improve test control of the CRM road performance based on the discovered flaws.Besides,the properties of reclaimed asphalt pavement(RAP),including the content of old asphalt,penetration index,passing rate of 4.75 mm sieve,and gradation change rate after extraction,were examined.The effects of RAP characteristics on splitting tensile strength,water stability,the high-and low-temperature performance of emulsified asphalt CRM were studied.The results show that the optimum moisture content of CRM should be determined when the compaction work matches the specimen’s molding work.Among the analyzed methods of bulk specific gravity assessment,the dry-surface and CoreLok methods provide more robust and accurate results than the wax-sealing method,while the dry-surface method is the most cost-efficient.The modified theoretical maximum relative density test method is proposed,which can reduce the systematic error of the vacuum test method.The following RAP-CRM trends can be observed.The lower the content of old asphalt and the smaller the change rate of gradation,the smaller the voids and the better the water stability of CRM.The greater the penetration of old asphalt,the higher the fracture work and low-temperature splitting strength.The greater the penetration,the higher the passing rate of 4.75 mm sieve after extraction,and the worse the high-temperature performance of CRM.展开更多
The department of Tillabéri is primarily affected by climatic phenomena, impacting crop yields, growing cycles, and consequently, the economic outcomes of agricultural operations. The objective of this study is t...The department of Tillabéri is primarily affected by climatic phenomena, impacting crop yields, growing cycles, and consequently, the economic outcomes of agricultural operations. The objective of this study is to analyze these impacts of climate disruption on the economic performance of farms. The methodology adopted for this study combined documentary research with field surveys conducted on a sample of 250 randomly selected farmers. The analytical methods used mainly consisted of linear regression, profitability calculations, and linear programming. The findings indicate that all productions across different crops have experienced a decrease over the past 30 years. For instance, the production of millet, sorghum, and cowpea, which were respectively 812 kg/ha, 260 kg/ha, and 100 kg/ha between the last 30 and 20 years, has now dropped to 412 kg/ha, 106 kg/ha, and 46 kg/ha respectively. A negative and significant effect on agricultural net margin was observed due to variables such as flooding, drought, pest invasion in rice fields, and temperature changes. Smallholder farms show a relatively low margin (46%) to cover their fixed costs, which may indicate a risk if fixed expenses are high. Furthermore, the analysis results from linear programming reveal that farmers could achieve an additional net profit per hectare of 116,861 FCFA, 217201.5 FCFA, and 291988.2 FCFA respectively for small, medium, and large producers by managing variable costs and health-related expenses for households.展开更多
NOx sensors, as a core component of diesel engine exhaust treatment system, play an important role in exhaust emission control, which can accurately and quickly detect the NOx and O2 concentration. It has become a nec...NOx sensors, as a core component of diesel engine exhaust treatment system, play an important role in exhaust emission control, which can accurately and quickly detect the NOx and O2 concentration. It has become a necessary option for the detection of existing exhaust emission standards. At present, there is limited and scattered information on knowledge and test methods of NOx sensors, the research of NOx sensors has become a challenging research topic at home and abroad. Based on these requirements, the article systematically integrates the knowledge of principle and testing methods. First of all, through introducing functional description of NOx sensors and the basic principle of NOx sensors, the relevant scholars can have an overall understanding of the product and master the operation mode of products. Secondly, the current status of performance test bench and methods of NOx sensors were described, which can contribute to having a clear understanding of the development process. After that, a new structure of NOx sensors test bench was purposed, which contains six major units including standard gas source, gas mixing unit, analyzer measurement unit, sensor measurement unit, data processing and display unit, exhaust gas treatment unit. And the test bench was validated. The experimental results show that the test bench has the advantages of high-repeatability, high reliability and low cost. And it can realize automatic detection of multiple target values, which is worthy further promotion. Thereby, the article can contribute to the development of its technology indirectly.展开更多
This study was designed to determine factors that influence market performance of avocado fruits among smallholder farmers in Mbeya and Songwe regions. A cross section research design entailing 209 farmers from five (...This study was designed to determine factors that influence market performance of avocado fruits among smallholder farmers in Mbeya and Songwe regions. A cross section research design entailing 209 farmers from five (5) districts of two (2) regions and 15 key informants;5 local service providers (LSP), 5 traders/brokers and 5 district extension officers (DEO) were involved in the study. Random selection procedures were used to select avocado producers and purposive selection procedures were used to select key informants. The study employed survey questionnaires to collect data from avocado farmers and structured interview to collect data from key informants. Collected data were analyzed with an aid of descriptive statistics and linear regression model was used to determine significant factors that determine market prices of avocado fruits among smallholder farmers. The demographic characteristics of avocado farmers showed that;61.2% of farmers had age between 36 to 59 years old, 84.7% were married, 74.6% had primary education level, average number of 5 members of the family, average 4.3 acres of owned land and 1.8 acres planted with avocado. Moreover, findings showed that 90.9% grew improved avocado varieties. Farm gate (88.5%) was the major market outlet chosen by avocado farmers. Local merchants and processors were the major buyers of the produced avocado. Results from linear regression analysis showed that variety grown (P P P P < 0.05) were factors that statistically influenced market prices for avocado fruits. The study concluded that despite the remarkable contributions to livelihood of the farmers yet, it is highly fragile on market prices. Therefore, the study recommends the need to establish market systems that will govern avocado fruits marketing for sustainability of the sub-sector.展开更多
Background: The study’s primary research suggests the relationship between high-school international students in China’s sleep quality and learning efficiency which is academic performance. Considering the effect of...Background: The study’s primary research suggests the relationship between high-school international students in China’s sleep quality and learning efficiency which is academic performance. Considering the effect of Chinese traditional cultural background, this study mainly investigates Chinese international high school students’ sleeping quality and patterns through the Pittsburgh Sleep Quality Index. Methods: A sample of 249 Chinese high school students in the Pearl River Region completed the questionnaire about their sleep quality using PSQI, their academic performance, and socio-demographic factors one month before the final exam in July 2023. Results: None of the students have good sleep quality, according to the PSQI;40.8% of students have poor sleep quality, and 59.2% have significant sleep disturbance. The results of ordinal logistic regression show that good sleep quality is positively associated with good academic performance. Conclusion: Our findings highlight the association between sleep and academic performance on the unique sleep patterns of Chinese international high school students, who often follow very different sleep patterns from other conventional students enrolled in the regular curriculum. High school students suffer from severe sleep deprivation and poor sleep quality. Under great academic stress, Chinese high school students should know the importance of sleep, balance sleep, and study.展开更多
This study was conducted at Fafan Research Center, Golajo research site to evaluate the effect of Moringa stenopetala and pigeon pea leaf supplementation on growth performance of short-eared Somali goat breed. A total...This study was conducted at Fafan Research Center, Golajo research site to evaluate the effect of Moringa stenopetala and pigeon pea leaf supplementation on growth performance of short-eared Somali goat breed. A total of fifteen yearling indigenous short-eared Somali goat breeds with an initial weight of 15.2 ± 0.30 kg were assigned to three treatment groups using completely randomized design. Pigeon pea (Pp) and Moringa stenopetala (MS) feeds were formulated using 0%, 5%, and 10% inclusion levels of MSLM and PPLM as experimental diets, respectively. The feed of the experiment was prepared in two levels (2 kg of Moringa stenopetala and 2 kg of pigeon pea) and was supplemented to experimental animals in treatments one and two, respectively. The average e initial body weight of selected male goats was 18.82 ± 0.37, 18.8 ± 0.37 and 17.8 ± 0.37 kg under treatment groups T1, T2 and control respectively. Data was analyzed using general linear model (GLM) procedure of SAS computer package Version 9.0 (SAS, 2002). The final weights gain (FWG) of goats on T1 and T2 of experimental group was significantly (P 0.05) the final weight gain of goat supplemented on Moringa stenopetala (T1) and pigeon pea levels (T2). The mean average weight gains (AWG) obtained from the supplemented group in this study were 7.50 ± 0.37 and 7.82 ± 0.37 kg for T1 and T2, whereas mean weight gains for un-supplemented goats were found to be 6.26 ± 0.37 kg. Feeding of dried Moringa stenopetala and pigeon pea leaves mixture improved body weights and average daily body weight gain without affecting feed intake and overall health of Somali goat breed. As Moringa stenopetala and pigeon pea leaves are rich nitrogen/protein source, they can be used effectively as substitute for conventional concentrate in the diet of growing goats at small holder farmer’s level where they can be grown in abundance. Therefore, for higher quality of forage and higher total DM yield for animal feeding, moringa should be harvested at wider harvesting intervals of at least 6th- to 8th-week intervals. Similarly, for pigeon peas, 4- to 6-week harvesting interval can result in optimum forage as well as feed quality and resulted in better growth performances for Somali short-eared goat breeds.展开更多
Aeroengines,often regarded as the heart of aircraft,are crucial for flight safety and performance.Comprehensive performance evaluation of aeroengines supports Prognostics and Health Management(PHM)and aeroengine digit...Aeroengines,often regarded as the heart of aircraft,are crucial for flight safety and performance.Comprehensive performance evaluation of aeroengines supports Prognostics and Health Management(PHM)and aeroengine digital engineering.Due to their highly integrated nature,aeroengines present challenges in performance evaluation because their test-run data are high-dimensional,large-scale,and exhibit strong nonlinear correlations among test indicators.To solve this problem,this study proposes a unified framework of the comprehensive performance evaluation of aeroengines to assess performance objectively and globally.Specifically,the network model and the dynamics model of aeroengine performance are constructed driven by test-run data,which can explain the patterns of system state changes and the internal relationship,and depict the system accurately.Based on that,three perturbations in the model are used to simulate three fault modes of aeroengines.Moreover,the comprehensive performance evaluation indexes of aeroengines are proposed to evaluate the performance dynamically from two dimensions,the coupling performance and the activity performance.Thirteen test-run qualified and four test-run failed aeroengines are used to validate and establish the qualified ranges.The results demonstrate that the comprehensive evaluation indexes can distinguish test-run qualified and test-run failed aeroengines.By changing the dynamic parameters,the comprehensive performance under any thrust and inlet guide vanes(IGV)angle can be estimated,broadening the test-run scenarios beyond a few typical states.This novel approach offers significant advancements for the comprehensive performance evaluation and management of aeroengines,paving the way for future PHM and aeroengine digital engineering developments.展开更多
Sweet potato is one of the most important crops in Côte d’Ivoire. However, some constraints related to climate change limit its production. This study evaluated the agronomic and technological performances of ei...Sweet potato is one of the most important crops in Côte d’Ivoire. However, some constraints related to climate change limit its production. This study evaluated the agronomic and technological performances of eight varieties of orange-fleshed of sweet potato (Ipomoea batatas (L.) to identify the most promising ones. The results show three groups of varieties with different agronomic performances. Group 1 composed of Irene and Vita is characterized by low production of small and large tuberous roots, low number of productive plants and low yield. Group 2 consisting mainly of Kabode is characterized by high production and weight of large tuberous roots as well as high yield. Group 3, composed of Tacha-2 Ininda, Ejumula Gloria, TIB-440060, CIP-199062-1, Bela bela is characterized by high production of small and large tuberous roots, high number of productive plants and average yield. The TIB-440060 variety has a recovery rate of 100%. The Irene, Kabode, Vita, Kabode varieties were resistant to viral and fungal diseases. In terms of technological quality, the TIB-440060 and CIP-199062-1 varieties have the best organoleptic qualities. Given the agronomic performances of the Kabode, TIB-440060 and CIP-199062-1 varieties, could be selected as the elites varieties and distributed to producers.展开更多
A steel-concrete composite cable-stayed bridge features integrated steel girders and concrete decks linked by shear connectors to support loads,but stress concentration in wet joints can lead to cracking.In-situ tests...A steel-concrete composite cable-stayed bridge features integrated steel girders and concrete decks linked by shear connectors to support loads,but stress concentration in wet joints can lead to cracking.In-situ tests were conducted on key sections of steel-concrete composite cable-stayed bridges to analyze the stress-strain evolution of wet joints under environmental factors,constraints,and complex construction processes.The coordinated working performance of the bridge decks was also analyzed.The results indicate that temperature is the key factor affecting the stresses and strains in wet joint concrete.Approximately 7 days after casting the wet joint concrete,the strains at each measurement point of the wet joint are approximately negatively correlated with the temperature change at the measurement point.Different locations within the wet joints have respective impacts,presenting potential weak points.Construction conditions have a certain impact on the stress and strain of the wet joint.The top deck of the steel box girder is not fully bonded to the bottom surface of the wet joints,resulting in a certain strain difference after loading.To further analyze the cooperative working performance of steel box girders and concrete wet joint bridge deck systems,finite element analysis was conducted on composite girder structures.A stiffness calculation method for shear connectors based on numerical simulation was proposed.The results indicate that strain differences can cause interface slip in composite girders.This slip leads to increased deflection of the composite girders and increased tensile stress in the bottom plate of the steel box girders.This study clarifies the stress conditions and factors affecting wet joints during construction,preventing early cracking,and offers precise data for a full bridge finite element model.展开更多
Zinc oxide(ZnO),as a broadband gap semiconductor material,exhibits unique physical and chemical properties that make it highly suitable for optoelectronics,piezoelectric devices,and gas-sensitive sensors,showing signi...Zinc oxide(ZnO),as a broadband gap semiconductor material,exhibits unique physical and chemical properties that make it highly suitable for optoelectronics,piezoelectric devices,and gas-sensitive sensors,showing significant potential for various applications.This paper focuses on the regulation and application of ZnO-based p-n junctions and piezoelectric devices.It discusses in detail the preparation of ZnO materials,the construction of p-n junctions,the optimization of piezoelectric device performance,and its application in various fields.By employing different preparation methods and strategies,high-quality ZnO thin films can be grown,and effective control of p-type conductivity achieved.This study provides both a theoretical foundation and technical support for controlling the performance of ZnO-based piezoelectric devices,as well as paving new pathways for the broader application of ZnO materials.展开更多
The fixed-setting face-milled curvilinear cylindrical gear features teeth that are arc-shaped along the longitudinal direction.Some researchers hypothesize that this arc-tooth may enhance the lubrication conditions of...The fixed-setting face-milled curvilinear cylindrical gear features teeth that are arc-shaped along the longitudinal direction.Some researchers hypothesize that this arc-tooth may enhance the lubrication conditions of the gear.This study focuses on this type of gear,employing both finite element analysis(FEA)and analytical methods to determine the input parameters required for elastohydrodynamic lubrication(EHL)analysis.The effects of assembly errors,tooth surface modifications,load,and face-milling cutter radius on the lubrication performance of these gears are systematically investigated.The finite element model(FEM)of the gear pair is utilized to calculate the coordinates of contact points on the tooth surface and the corresponding contact pressures at the tooth surface nodes throughout a meshing cycle.Subsequently,the normal load on specific gear teeth is determined using a gradient-based approach.Entrainment speed,slip-to-roll ratio,and effective radius near the contact points on the tooth surface are derived through analytical methods.The data obtained from FEA serve as input parameters for EHL simulations.The lubrication performance of the curvilinear cylindrical gear is evaluated through example studies.The findings indicate that using FEA to provide input parameters for EHL simulations can reveal the occurrence of edge contact phenomena during gear meshing,allowing for a more accurate representation of the gear’s lubrication conditions.The lubrication performance of the curvilinear cylindrical gear is shown to be independent of the face-milling cutter radius but is significantly influenced by the size of the contact pattern on the tooth surface.Curvilinear gears with larger contact patterns demonstrate superior lubrication performance.展开更多
Applied field magnetoplasmadynamic thrusters(AF-MPDTs), with their high specific impulse and considerable thrust, are increasingly favored for large-scale space missions. This paper presents the composition, functiona...Applied field magnetoplasmadynamic thrusters(AF-MPDTs), with their high specific impulse and considerable thrust, are increasingly favored for large-scale space missions. This paper presents the composition, functionality, and testing methods of a high-power electric propulsion performance testing system, along with the vacuum ignition test results of a 100 kW superconducting MPD thruster. The relationships between thruster efficiency, magnetic field strength, current,and mass flow rate are analyzed. For each combination of current and flow rate in an AF-MPDT, there is an optimal magnetic field strength where the thruster efficiency reaches its peak. Under conditions of 320 A current and 60 mg/s flow rate,the optimal magnetic field strength is 0.5 T, yielding the highest thruster efficiency of 71%.展开更多
The oscillating hydrofoil represents a promising technology for harvesting energy from tidal currents.While previous research has primarily focused on oscillating hydrofoils utilizing a fully activated control strateg...The oscillating hydrofoil represents a promising technology for harvesting energy from tidal currents.While previous research has primarily focused on oscillating hydrofoils utilizing a fully activated control strategy,the industry predominantly employs a semi-activated control strategy in existing tidal current energy converters.It is essential to identify the differences in predicted energy-harvesting performance between these two controlling strategies through experimental modeling or numerical studies.Furthermore,the suitability of the fully activated control strategy in predicting the energy-harvesting capabilities of oscillating hydrofoils is evaluated.The 2D numerical models of hydrofoil based on fully activated and semi-activated control strategies have been developed and validated.The amplitudes of heaving and pitching movements for the fully activated hydrofoil are determined to match those of the semi-activated hydrofoil.The results show that the main difference between the two control strategies lies in the phase shift occurring between the pitching and heaving motions.This phase shift affects the lift force and its coordination with the heaving velocity,which in turn affects the power output.Notably,the maximum relative efficiency difference obtained between the fully activated and semi-activated control strategies can reach 191%.展开更多
With the widespread application of Internet of Things(IoT)technology,the processing of massive realtime streaming data poses significant challenges to the computational and data-processing capabilities of systems.Alth...With the widespread application of Internet of Things(IoT)technology,the processing of massive realtime streaming data poses significant challenges to the computational and data-processing capabilities of systems.Although distributed streaming data processing frameworks such asApache Flink andApache Spark Streaming provide solutions,meeting stringent response time requirements while ensuring high throughput and resource utilization remains an urgent problem.To address this,the study proposes a formal modeling approach based on Performance Evaluation Process Algebra(PEPA),which abstracts the core components and interactions of cloud-based distributed streaming data processing systems.Additionally,a generic service flow generation algorithmis introduced,enabling the automatic extraction of service flows fromthe PEPAmodel and the computation of key performance metrics,including response time,throughput,and resource utilization.The novelty of this work lies in the integration of PEPA-based formal modeling with the service flow generation algorithm,bridging the gap between formal modeling and practical performance evaluation for IoT systems.Simulation experiments demonstrate that optimizing the execution efficiency of components can significantly improve system performance.For instance,increasing the task execution rate from 10 to 100 improves system performance by 9.53%,while further increasing it to 200 results in a 21.58%improvement.However,diminishing returns are observed when the execution rate reaches 500,with only a 0.42%gain.Similarly,increasing the number of TaskManagers from 10 to 20 improves response time by 18.49%,but the improvement slows to 6.06% when increasing from 20 to 50,highlighting the importance of co-optimizing component efficiency and resource management to achieve substantial performance gains.This study provides a systematic framework for analyzing and optimizing the performance of IoT systems for large-scale real-time streaming data processing.The proposed approach not only identifies performance bottlenecks but also offers insights into improving system efficiency under different configurations and workloads.展开更多
Detonation performance is crucial for evaluating the power of high explosives(HEs),and the equation of state(EOS)that accurately describes the high-temperature,high-pressure,and high-temperature,medium-pressure states...Detonation performance is crucial for evaluating the power of high explosives(HEs),and the equation of state(EOS)that accurately describes the high-temperature,high-pressure,and high-temperature,medium-pressure states of detonation products is key to assessing the damage efficiency of these energetic materials.This article examines the limitations of the VLW EOS in representing the thermodynamic states of explosive detonation gas products under high-temperature and medium-to high-pressure conditions.A new gas EOS for detonation products,called VHL(Virial-Han-Long),is proposed.The accuracy of VHL in describing gas states under high-temperature and medium-to high-pressure conditions is verified,and its performance in evaluating explosive detonation and working capabilities is explored.The results demonstrate that VHL exhibits high precision in calculating detonation performance.Subsequently,the detonation performance of three new HEs(ICM-101,ONC,and TNAZ)was calculated and compared to traditional HEs(TATB,CL-20,and HMX).The results indicate that ONC has superior detonation performance compared to the other explosives,while ICM-101 shows a detonation velocity similar to CL-20 but with slightly lower detonation pressure.The detonation characteristics of TNAZ are comparable to those of the standard HE HMX.From the perspective of products,considering the comprehensive work performance(mechanical work and detonation heat),both ONC and ICM-101demonstrate relatively superior performance.展开更多
During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped wit...During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped with independent air ducts.In this paper,a two-step method is used for numerical computation:(1)obtaining the temporal and spatial transient node data of the flow field sections during the train-passing simulation and(2)using the data as the input data for the equipment compartment simulation.In addition,this paper also compares the difference in equipment ventilation between the single-train and trainpassing scenarios in real vehicle tests.The results indicate that the primary factors influencing ventilation effectiveness are the aerodynamic compression and deceleration of airflow induced by the other train's nose,as well as the instability of the external flow field in the wake of the other train.During train crossing,the air is forced into the air duct,with a maximum ratio of the airflow in-duct to the airflow out-duct reaching 3.2.The average mass flow falls below the rated mass flow for the converter.Compared to the rated air volume of converter,the maximum suppression rates obtained from testing and simulation are-24.5%and-16.8%,respectively.Compared to the single-train operation,the maximum suppression rates obtained from testing and simulation are-15%and-18%,respectively.These findings provide valuable insights into the design and operation of high-speed trains.展开更多
A novel precipitate-free Mg-0.1Sn anode with a homogeneous equal-axis grain structure was developed and rolled successfully at 573 K.Electrochemical test results indicate that the Mg-0.1Sn alloy exhibits enhanced anod...A novel precipitate-free Mg-0.1Sn anode with a homogeneous equal-axis grain structure was developed and rolled successfully at 573 K.Electrochemical test results indicate that the Mg-0.1Sn alloy exhibits enhanced anode dissolution kinetics.A Mg-air battery prepared using this anode exhibits a cell voltage of 1.626 V at 0.5 mA/cm^(2),reasonable anodic efficiency of 58.17%,and good specific energy of 1730.96 mW·h/g at 10 mA/cm^(2).This performance is attributed to the effective reactive anode surface,the suppressed chunk effect,and weak self-corrosion owing to the homogeneous basal texture.展开更多
Background The present experiment aimed to evaluate the effects of commercially processed former foodstuffs(cFF)as dietary substitutes of corn,soybean meal and soybean oil on the growth performance,apparent total trac...Background The present experiment aimed to evaluate the effects of commercially processed former foodstuffs(cFF)as dietary substitutes of corn,soybean meal and soybean oil on the growth performance,apparent total tract digestibil-ity(ATTD),hematobiochemical profiles,and liver gene abundance in broiler chickens.Two hundred one-day-old male ROSS-308 chicks were assigned to 4 dietary groups(5 replicates of ten birds per replicate)according to their average body weight(BW,38.0±0.11 g).All groups received a two-phase feeding program:starter,d 1–12 and grower,d 12–33.The control group(cFF0)was fed a standard commercial feed based on corn,soybean meal and soybean oil.The other three groups received diets in which the feed based on corn,soybean meal,and soybean oil was partially replaced with cFF at a substitution level of 6.25%(cFF6.25),12.5%(cFF12.5)or 25%(cFF25)for the following 33 d.Results The growth performance data showed no differences in BW or average daily gain among groups,although the average daily feed intake decreased during the grower period(12–33 d)and over entire experimental period(1–33 d)in a linear manner as the cFF inclusion level rose(P=0.026),positively affecting the gain to feed ratio(P=0.001).The ATTD of dry matter of the cFF-fed groups were greater with respect to control group and increased throughout the experimental period,whereas the ATTD of ether extract linearly decreased with increasing levels of cFF-fed groups compared with control group and throughout the experimental period(P<0.05).Additionally,a lin-ear increase in the heterophil to lymphocyte ratio,serum cholesterol,triglycerides and alanine-aminotransferase were observed with increasing dietary levels of cFF(P<0.05);however,no differences were observed in lipoprotein lipase or sterol regulatory element binding transcription factor gene abundance.Conclusions The results of this experiment demonstrate that it is possible to incorporate cFF into nutritionally balanced diets for broiler chickens,even up to 25%substitution levels,for up to 33 d without adversely impacting the overall growth performance of male broiler chickens raised under commercial conditions.Further studies are essential to validate the hematological trait findings.展开更多
In petroleum extraction,the sealing surfaces of bolted joints are susceptible to damage due to the high-temperature and high-pressure conditions in wellbores.This damage adversely affects sealing performance,consequen...In petroleum extraction,the sealing surfaces of bolted joints are susceptible to damage due to the high-temperature and high-pressure conditions in wellbores.This damage adversely affects sealing performance,consequently leading to the failure and damage of threaded connections.In severe cases,it can result in considerable economic losses and trigger safety accidents.The sealing performance of special bolted joints holds crucial importance for production efficiency,output,equipment lifespan,and cost control.Enhancing the sealing perfor-mance of threaded connections can have a positive impact on industrial production and environmental protection.The existing research on American Petroleum Institute threaded joints has been thorough and has obtained a series of excellent results.However,the research on the sealing damage mechanism of threaded connections under complex well conditions lacks sufficient depth and that on new sealing technology is scarce.This study proposes a half-size evaluation test to address the abovementioned problem.Based on this test,an investigation into the sealing performance of threaded connections under high-temperature,cyclic loading,and high-temperature creep conditions is conducted.This study uses a combined approach of finite element methods and experiments to investigate the impact of different makeup torques on the sealing performance of premium threaded connections(PTCs).The results of the half-size evaluation test indicate that temperature notably influences the sealing performance of threaded connections.The continuous action of high temperatures causes contact pressure and sealing performance to decrease,and sealing contact pressure increases after cooling.Finite element and test results show that for a certain joint A,the greater the torque,the higher the critical sealing pressure of the thread,and the better the sealing performance.The research on the sealing damage mechanism of PTCs provides a scientific basis and theoretical guidance for the further optimization and development of PTCs.展开更多
Crude petroleum pollution causes some serious ecological disasters in the ocean.Marine sediment microbial fuel cells(MSMFCs)have been utilized as a novel method for in-situ degradation and a long-term power source.Her...Crude petroleum pollution causes some serious ecological disasters in the ocean.Marine sediment microbial fuel cells(MSMFCs)have been utilized as a novel method for in-situ degradation and a long-term power source.Herein,the effect of different concentrations of rhamnolipids biosurfactant on the electrochemical performance of MSMFCs anode and the higher efficiency of oil degradation are creatively investigated.The results indicate that the anode in sediment containing rhamnolipids effectively enriches the indigenous electrogenic Pseudophaeobacter and Pseudomonas,which significantly enhances the electrochemical performance of the MSMFCs.Under rhamnolipids at the concentration of 200 mg kg^(-1)in sediment,the anode specific capacitance(401.45 Fm^(-2)),exchange current density(4.87×10^(-2)mAm^(-2)),and cell maximum power density(140.24 mWm^(-2))increase by 2.50,38.65,and 2.11 times,respectively,in comparison with its natural sediment.And the oil degradation rate(40.06%)was higher than the blank(17.55%).It demonstrates that the synergistic effect between electrochemical catalytic degradation and emulsifying solubilization of rhamnolipids surfactant directly accelerates the degradation of petroleum in marine sediment,which will provide a novel method and theoretical guidance for in-situ degradation and efficient removal of crude petroleum on ocean floor.展开更多
文摘The available test methods for optimal moisture content of cold recycled mixture(CRM)as well as its bulk specific gravity,and theoretical maximum relative density were analyzed in this work.Some test improvements were suggested to improve test control of the CRM road performance based on the discovered flaws.Besides,the properties of reclaimed asphalt pavement(RAP),including the content of old asphalt,penetration index,passing rate of 4.75 mm sieve,and gradation change rate after extraction,were examined.The effects of RAP characteristics on splitting tensile strength,water stability,the high-and low-temperature performance of emulsified asphalt CRM were studied.The results show that the optimum moisture content of CRM should be determined when the compaction work matches the specimen’s molding work.Among the analyzed methods of bulk specific gravity assessment,the dry-surface and CoreLok methods provide more robust and accurate results than the wax-sealing method,while the dry-surface method is the most cost-efficient.The modified theoretical maximum relative density test method is proposed,which can reduce the systematic error of the vacuum test method.The following RAP-CRM trends can be observed.The lower the content of old asphalt and the smaller the change rate of gradation,the smaller the voids and the better the water stability of CRM.The greater the penetration of old asphalt,the higher the fracture work and low-temperature splitting strength.The greater the penetration,the higher the passing rate of 4.75 mm sieve after extraction,and the worse the high-temperature performance of CRM.
文摘The department of Tillabéri is primarily affected by climatic phenomena, impacting crop yields, growing cycles, and consequently, the economic outcomes of agricultural operations. The objective of this study is to analyze these impacts of climate disruption on the economic performance of farms. The methodology adopted for this study combined documentary research with field surveys conducted on a sample of 250 randomly selected farmers. The analytical methods used mainly consisted of linear regression, profitability calculations, and linear programming. The findings indicate that all productions across different crops have experienced a decrease over the past 30 years. For instance, the production of millet, sorghum, and cowpea, which were respectively 812 kg/ha, 260 kg/ha, and 100 kg/ha between the last 30 and 20 years, has now dropped to 412 kg/ha, 106 kg/ha, and 46 kg/ha respectively. A negative and significant effect on agricultural net margin was observed due to variables such as flooding, drought, pest invasion in rice fields, and temperature changes. Smallholder farms show a relatively low margin (46%) to cover their fixed costs, which may indicate a risk if fixed expenses are high. Furthermore, the analysis results from linear programming reveal that farmers could achieve an additional net profit per hectare of 116,861 FCFA, 217201.5 FCFA, and 291988.2 FCFA respectively for small, medium, and large producers by managing variable costs and health-related expenses for households.
文摘NOx sensors, as a core component of diesel engine exhaust treatment system, play an important role in exhaust emission control, which can accurately and quickly detect the NOx and O2 concentration. It has become a necessary option for the detection of existing exhaust emission standards. At present, there is limited and scattered information on knowledge and test methods of NOx sensors, the research of NOx sensors has become a challenging research topic at home and abroad. Based on these requirements, the article systematically integrates the knowledge of principle and testing methods. First of all, through introducing functional description of NOx sensors and the basic principle of NOx sensors, the relevant scholars can have an overall understanding of the product and master the operation mode of products. Secondly, the current status of performance test bench and methods of NOx sensors were described, which can contribute to having a clear understanding of the development process. After that, a new structure of NOx sensors test bench was purposed, which contains six major units including standard gas source, gas mixing unit, analyzer measurement unit, sensor measurement unit, data processing and display unit, exhaust gas treatment unit. And the test bench was validated. The experimental results show that the test bench has the advantages of high-repeatability, high reliability and low cost. And it can realize automatic detection of multiple target values, which is worthy further promotion. Thereby, the article can contribute to the development of its technology indirectly.
文摘This study was designed to determine factors that influence market performance of avocado fruits among smallholder farmers in Mbeya and Songwe regions. A cross section research design entailing 209 farmers from five (5) districts of two (2) regions and 15 key informants;5 local service providers (LSP), 5 traders/brokers and 5 district extension officers (DEO) were involved in the study. Random selection procedures were used to select avocado producers and purposive selection procedures were used to select key informants. The study employed survey questionnaires to collect data from avocado farmers and structured interview to collect data from key informants. Collected data were analyzed with an aid of descriptive statistics and linear regression model was used to determine significant factors that determine market prices of avocado fruits among smallholder farmers. The demographic characteristics of avocado farmers showed that;61.2% of farmers had age between 36 to 59 years old, 84.7% were married, 74.6% had primary education level, average number of 5 members of the family, average 4.3 acres of owned land and 1.8 acres planted with avocado. Moreover, findings showed that 90.9% grew improved avocado varieties. Farm gate (88.5%) was the major market outlet chosen by avocado farmers. Local merchants and processors were the major buyers of the produced avocado. Results from linear regression analysis showed that variety grown (P P P P < 0.05) were factors that statistically influenced market prices for avocado fruits. The study concluded that despite the remarkable contributions to livelihood of the farmers yet, it is highly fragile on market prices. Therefore, the study recommends the need to establish market systems that will govern avocado fruits marketing for sustainability of the sub-sector.
文摘Background: The study’s primary research suggests the relationship between high-school international students in China’s sleep quality and learning efficiency which is academic performance. Considering the effect of Chinese traditional cultural background, this study mainly investigates Chinese international high school students’ sleeping quality and patterns through the Pittsburgh Sleep Quality Index. Methods: A sample of 249 Chinese high school students in the Pearl River Region completed the questionnaire about their sleep quality using PSQI, their academic performance, and socio-demographic factors one month before the final exam in July 2023. Results: None of the students have good sleep quality, according to the PSQI;40.8% of students have poor sleep quality, and 59.2% have significant sleep disturbance. The results of ordinal logistic regression show that good sleep quality is positively associated with good academic performance. Conclusion: Our findings highlight the association between sleep and academic performance on the unique sleep patterns of Chinese international high school students, who often follow very different sleep patterns from other conventional students enrolled in the regular curriculum. High school students suffer from severe sleep deprivation and poor sleep quality. Under great academic stress, Chinese high school students should know the importance of sleep, balance sleep, and study.
文摘This study was conducted at Fafan Research Center, Golajo research site to evaluate the effect of Moringa stenopetala and pigeon pea leaf supplementation on growth performance of short-eared Somali goat breed. A total of fifteen yearling indigenous short-eared Somali goat breeds with an initial weight of 15.2 ± 0.30 kg were assigned to three treatment groups using completely randomized design. Pigeon pea (Pp) and Moringa stenopetala (MS) feeds were formulated using 0%, 5%, and 10% inclusion levels of MSLM and PPLM as experimental diets, respectively. The feed of the experiment was prepared in two levels (2 kg of Moringa stenopetala and 2 kg of pigeon pea) and was supplemented to experimental animals in treatments one and two, respectively. The average e initial body weight of selected male goats was 18.82 ± 0.37, 18.8 ± 0.37 and 17.8 ± 0.37 kg under treatment groups T1, T2 and control respectively. Data was analyzed using general linear model (GLM) procedure of SAS computer package Version 9.0 (SAS, 2002). The final weights gain (FWG) of goats on T1 and T2 of experimental group was significantly (P 0.05) the final weight gain of goat supplemented on Moringa stenopetala (T1) and pigeon pea levels (T2). The mean average weight gains (AWG) obtained from the supplemented group in this study were 7.50 ± 0.37 and 7.82 ± 0.37 kg for T1 and T2, whereas mean weight gains for un-supplemented goats were found to be 6.26 ± 0.37 kg. Feeding of dried Moringa stenopetala and pigeon pea leaves mixture improved body weights and average daily body weight gain without affecting feed intake and overall health of Somali goat breed. As Moringa stenopetala and pigeon pea leaves are rich nitrogen/protein source, they can be used effectively as substitute for conventional concentrate in the diet of growing goats at small holder farmer’s level where they can be grown in abundance. Therefore, for higher quality of forage and higher total DM yield for animal feeding, moringa should be harvested at wider harvesting intervals of at least 6th- to 8th-week intervals. Similarly, for pigeon peas, 4- to 6-week harvesting interval can result in optimum forage as well as feed quality and resulted in better growth performances for Somali short-eared goat breeds.
基金supported by the National Natural Science Foundation of China(72231008,72171193,and 72071153)the Science and Technology Innovation Group Program of Shaanxi Province(2024RS-CXTD-28)the Open Fund of Intelligent Control Laboratory(ICL-2023-0304).
文摘Aeroengines,often regarded as the heart of aircraft,are crucial for flight safety and performance.Comprehensive performance evaluation of aeroengines supports Prognostics and Health Management(PHM)and aeroengine digital engineering.Due to their highly integrated nature,aeroengines present challenges in performance evaluation because their test-run data are high-dimensional,large-scale,and exhibit strong nonlinear correlations among test indicators.To solve this problem,this study proposes a unified framework of the comprehensive performance evaluation of aeroengines to assess performance objectively and globally.Specifically,the network model and the dynamics model of aeroengine performance are constructed driven by test-run data,which can explain the patterns of system state changes and the internal relationship,and depict the system accurately.Based on that,three perturbations in the model are used to simulate three fault modes of aeroengines.Moreover,the comprehensive performance evaluation indexes of aeroengines are proposed to evaluate the performance dynamically from two dimensions,the coupling performance and the activity performance.Thirteen test-run qualified and four test-run failed aeroengines are used to validate and establish the qualified ranges.The results demonstrate that the comprehensive evaluation indexes can distinguish test-run qualified and test-run failed aeroengines.By changing the dynamic parameters,the comprehensive performance under any thrust and inlet guide vanes(IGV)angle can be estimated,broadening the test-run scenarios beyond a few typical states.This novel approach offers significant advancements for the comprehensive performance evaluation and management of aeroengines,paving the way for future PHM and aeroengine digital engineering developments.
文摘Sweet potato is one of the most important crops in Côte d’Ivoire. However, some constraints related to climate change limit its production. This study evaluated the agronomic and technological performances of eight varieties of orange-fleshed of sweet potato (Ipomoea batatas (L.) to identify the most promising ones. The results show three groups of varieties with different agronomic performances. Group 1 composed of Irene and Vita is characterized by low production of small and large tuberous roots, low number of productive plants and low yield. Group 2 consisting mainly of Kabode is characterized by high production and weight of large tuberous roots as well as high yield. Group 3, composed of Tacha-2 Ininda, Ejumula Gloria, TIB-440060, CIP-199062-1, Bela bela is characterized by high production of small and large tuberous roots, high number of productive plants and average yield. The TIB-440060 variety has a recovery rate of 100%. The Irene, Kabode, Vita, Kabode varieties were resistant to viral and fungal diseases. In terms of technological quality, the TIB-440060 and CIP-199062-1 varieties have the best organoleptic qualities. Given the agronomic performances of the Kabode, TIB-440060 and CIP-199062-1 varieties, could be selected as the elites varieties and distributed to producers.
文摘A steel-concrete composite cable-stayed bridge features integrated steel girders and concrete decks linked by shear connectors to support loads,but stress concentration in wet joints can lead to cracking.In-situ tests were conducted on key sections of steel-concrete composite cable-stayed bridges to analyze the stress-strain evolution of wet joints under environmental factors,constraints,and complex construction processes.The coordinated working performance of the bridge decks was also analyzed.The results indicate that temperature is the key factor affecting the stresses and strains in wet joint concrete.Approximately 7 days after casting the wet joint concrete,the strains at each measurement point of the wet joint are approximately negatively correlated with the temperature change at the measurement point.Different locations within the wet joints have respective impacts,presenting potential weak points.Construction conditions have a certain impact on the stress and strain of the wet joint.The top deck of the steel box girder is not fully bonded to the bottom surface of the wet joints,resulting in a certain strain difference after loading.To further analyze the cooperative working performance of steel box girders and concrete wet joint bridge deck systems,finite element analysis was conducted on composite girder structures.A stiffness calculation method for shear connectors based on numerical simulation was proposed.The results indicate that strain differences can cause interface slip in composite girders.This slip leads to increased deflection of the composite girders and increased tensile stress in the bottom plate of the steel box girders.This study clarifies the stress conditions and factors affecting wet joints during construction,preventing early cracking,and offers precise data for a full bridge finite element model.
基金The Natural Science Foundation of Guangdong Province(Project No.2023A1515012352)。
文摘Zinc oxide(ZnO),as a broadband gap semiconductor material,exhibits unique physical and chemical properties that make it highly suitable for optoelectronics,piezoelectric devices,and gas-sensitive sensors,showing significant potential for various applications.This paper focuses on the regulation and application of ZnO-based p-n junctions and piezoelectric devices.It discusses in detail the preparation of ZnO materials,the construction of p-n junctions,the optimization of piezoelectric device performance,and its application in various fields.By employing different preparation methods and strategies,high-quality ZnO thin films can be grown,and effective control of p-type conductivity achieved.This study provides both a theoretical foundation and technical support for controlling the performance of ZnO-based piezoelectric devices,as well as paving new pathways for the broader application of ZnO materials.
基金funded by the Sichuan Science and Technology Program(Project Nos.2024NSFSC0140,2023NSFSC0414,2022NSFSC0454)Panzhihua City Provincial Targeted Financial Resources Transfer Payment(Grant No.222Y2F-GG-04)+4 种基金Open Project of the Key Laboratory of Process Equipment and Control in Sichuan Province(ProjectNo.GK202211)Cultivation Research Project of PanzhihuaUniversity(ProjectNo.2023PY11)Open Project of Sichuan Provincial Engineering Technology Research Center for Advanced Manufacturing of Titanium Alloys(Project No.TM-2023-Z-02)Open Project of Panzhihua Key Laboratory of Advanced Manufacturing Technology(Project No.2022XJZD05).
文摘The fixed-setting face-milled curvilinear cylindrical gear features teeth that are arc-shaped along the longitudinal direction.Some researchers hypothesize that this arc-tooth may enhance the lubrication conditions of the gear.This study focuses on this type of gear,employing both finite element analysis(FEA)and analytical methods to determine the input parameters required for elastohydrodynamic lubrication(EHL)analysis.The effects of assembly errors,tooth surface modifications,load,and face-milling cutter radius on the lubrication performance of these gears are systematically investigated.The finite element model(FEM)of the gear pair is utilized to calculate the coordinates of contact points on the tooth surface and the corresponding contact pressures at the tooth surface nodes throughout a meshing cycle.Subsequently,the normal load on specific gear teeth is determined using a gradient-based approach.Entrainment speed,slip-to-roll ratio,and effective radius near the contact points on the tooth surface are derived through analytical methods.The data obtained from FEA serve as input parameters for EHL simulations.The lubrication performance of the curvilinear cylindrical gear is evaluated through example studies.The findings indicate that using FEA to provide input parameters for EHL simulations can reveal the occurrence of edge contact phenomena during gear meshing,allowing for a more accurate representation of the gear’s lubrication conditions.The lubrication performance of the curvilinear cylindrical gear is shown to be independent of the face-milling cutter radius but is significantly influenced by the size of the contact pattern on the tooth surface.Curvilinear gears with larger contact patterns demonstrate superior lubrication performance.
文摘Applied field magnetoplasmadynamic thrusters(AF-MPDTs), with their high specific impulse and considerable thrust, are increasingly favored for large-scale space missions. This paper presents the composition, functionality, and testing methods of a high-power electric propulsion performance testing system, along with the vacuum ignition test results of a 100 kW superconducting MPD thruster. The relationships between thruster efficiency, magnetic field strength, current,and mass flow rate are analyzed. For each combination of current and flow rate in an AF-MPDT, there is an optimal magnetic field strength where the thruster efficiency reaches its peak. Under conditions of 320 A current and 60 mg/s flow rate,the optimal magnetic field strength is 0.5 T, yielding the highest thruster efficiency of 71%.
基金supported by the Shandong Natural Science Foundation Youth Project(No.ZR2023QE075)the Open Project Program of Shandong Marine Aerospace Equipment Technological Innovation Center(No.MAETIC202210)the Shandong Natural Science Foundation Project(No.ZR2022ME145)。
文摘The oscillating hydrofoil represents a promising technology for harvesting energy from tidal currents.While previous research has primarily focused on oscillating hydrofoils utilizing a fully activated control strategy,the industry predominantly employs a semi-activated control strategy in existing tidal current energy converters.It is essential to identify the differences in predicted energy-harvesting performance between these two controlling strategies through experimental modeling or numerical studies.Furthermore,the suitability of the fully activated control strategy in predicting the energy-harvesting capabilities of oscillating hydrofoils is evaluated.The 2D numerical models of hydrofoil based on fully activated and semi-activated control strategies have been developed and validated.The amplitudes of heaving and pitching movements for the fully activated hydrofoil are determined to match those of the semi-activated hydrofoil.The results show that the main difference between the two control strategies lies in the phase shift occurring between the pitching and heaving motions.This phase shift affects the lift force and its coordination with the heaving velocity,which in turn affects the power output.Notably,the maximum relative efficiency difference obtained between the fully activated and semi-activated control strategies can reach 191%.
基金funded by the Joint Project of Industry-University-Research of Jiangsu Province(Grant:BY20231146).
文摘With the widespread application of Internet of Things(IoT)technology,the processing of massive realtime streaming data poses significant challenges to the computational and data-processing capabilities of systems.Although distributed streaming data processing frameworks such asApache Flink andApache Spark Streaming provide solutions,meeting stringent response time requirements while ensuring high throughput and resource utilization remains an urgent problem.To address this,the study proposes a formal modeling approach based on Performance Evaluation Process Algebra(PEPA),which abstracts the core components and interactions of cloud-based distributed streaming data processing systems.Additionally,a generic service flow generation algorithmis introduced,enabling the automatic extraction of service flows fromthe PEPAmodel and the computation of key performance metrics,including response time,throughput,and resource utilization.The novelty of this work lies in the integration of PEPA-based formal modeling with the service flow generation algorithm,bridging the gap between formal modeling and practical performance evaluation for IoT systems.Simulation experiments demonstrate that optimizing the execution efficiency of components can significantly improve system performance.For instance,increasing the task execution rate from 10 to 100 improves system performance by 9.53%,while further increasing it to 200 results in a 21.58%improvement.However,diminishing returns are observed when the execution rate reaches 500,with only a 0.42%gain.Similarly,increasing the number of TaskManagers from 10 to 20 improves response time by 18.49%,but the improvement slows to 6.06% when increasing from 20 to 50,highlighting the importance of co-optimizing component efficiency and resource management to achieve substantial performance gains.This study provides a systematic framework for analyzing and optimizing the performance of IoT systems for large-scale real-time streaming data processing.The proposed approach not only identifies performance bottlenecks but also offers insights into improving system efficiency under different configurations and workloads.
基金supported by the National Natural Science Foundation of China(Gant Nos.11372291 and 11902298)。
文摘Detonation performance is crucial for evaluating the power of high explosives(HEs),and the equation of state(EOS)that accurately describes the high-temperature,high-pressure,and high-temperature,medium-pressure states of detonation products is key to assessing the damage efficiency of these energetic materials.This article examines the limitations of the VLW EOS in representing the thermodynamic states of explosive detonation gas products under high-temperature and medium-to high-pressure conditions.A new gas EOS for detonation products,called VHL(Virial-Han-Long),is proposed.The accuracy of VHL in describing gas states under high-temperature and medium-to high-pressure conditions is verified,and its performance in evaluating explosive detonation and working capabilities is explored.The results demonstrate that VHL exhibits high precision in calculating detonation performance.Subsequently,the detonation performance of three new HEs(ICM-101,ONC,and TNAZ)was calculated and compared to traditional HEs(TATB,CL-20,and HMX).The results indicate that ONC has superior detonation performance compared to the other explosives,while ICM-101 shows a detonation velocity similar to CL-20 but with slightly lower detonation pressure.The detonation characteristics of TNAZ are comparable to those of the standard HE HMX.From the perspective of products,considering the comprehensive work performance(mechanical work and detonation heat),both ONC and ICM-101demonstrate relatively superior performance.
基金support by Technology R&D Program of China State Railway Group Co.,Ltd(Grant number N2022J013)the Hunan Provincial Innovation Foundation for Postgraduate(Grant number CX20220279)+1 种基金the Fundamental Research Funds for the Central Universities of Central South University(Grant number 2022ZZTS0193)China Scholarship Council(202106370112)。
文摘During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped with independent air ducts.In this paper,a two-step method is used for numerical computation:(1)obtaining the temporal and spatial transient node data of the flow field sections during the train-passing simulation and(2)using the data as the input data for the equipment compartment simulation.In addition,this paper also compares the difference in equipment ventilation between the single-train and trainpassing scenarios in real vehicle tests.The results indicate that the primary factors influencing ventilation effectiveness are the aerodynamic compression and deceleration of airflow induced by the other train's nose,as well as the instability of the external flow field in the wake of the other train.During train crossing,the air is forced into the air duct,with a maximum ratio of the airflow in-duct to the airflow out-duct reaching 3.2.The average mass flow falls below the rated mass flow for the converter.Compared to the rated air volume of converter,the maximum suppression rates obtained from testing and simulation are-24.5%and-16.8%,respectively.Compared to the single-train operation,the maximum suppression rates obtained from testing and simulation are-15%and-18%,respectively.These findings provide valuable insights into the design and operation of high-speed trains.
基金partially supported by the National Natural Science Foundation of China(No.51901153)Shanxi Scholarship Council of China(No.2019032)+1 种基金the Natural Science Foundation of Shanxi,China(No.202103021224049)the Shanxi Zhejiang University New Materials and Chemical Research Institute Scientific Research Project,China(No.2022SX-TD025)。
文摘A novel precipitate-free Mg-0.1Sn anode with a homogeneous equal-axis grain structure was developed and rolled successfully at 573 K.Electrochemical test results indicate that the Mg-0.1Sn alloy exhibits enhanced anode dissolution kinetics.A Mg-air battery prepared using this anode exhibits a cell voltage of 1.626 V at 0.5 mA/cm^(2),reasonable anodic efficiency of 58.17%,and good specific energy of 1730.96 mW·h/g at 10 mA/cm^(2).This performance is attributed to the effective reactive anode surface,the suppressed chunk effect,and weak self-corrosion owing to the homogeneous basal texture.
基金Department of Veterinary Sciences“Ricerca Locale–Linea A”.
文摘Background The present experiment aimed to evaluate the effects of commercially processed former foodstuffs(cFF)as dietary substitutes of corn,soybean meal and soybean oil on the growth performance,apparent total tract digestibil-ity(ATTD),hematobiochemical profiles,and liver gene abundance in broiler chickens.Two hundred one-day-old male ROSS-308 chicks were assigned to 4 dietary groups(5 replicates of ten birds per replicate)according to their average body weight(BW,38.0±0.11 g).All groups received a two-phase feeding program:starter,d 1–12 and grower,d 12–33.The control group(cFF0)was fed a standard commercial feed based on corn,soybean meal and soybean oil.The other three groups received diets in which the feed based on corn,soybean meal,and soybean oil was partially replaced with cFF at a substitution level of 6.25%(cFF6.25),12.5%(cFF12.5)or 25%(cFF25)for the following 33 d.Results The growth performance data showed no differences in BW or average daily gain among groups,although the average daily feed intake decreased during the grower period(12–33 d)and over entire experimental period(1–33 d)in a linear manner as the cFF inclusion level rose(P=0.026),positively affecting the gain to feed ratio(P=0.001).The ATTD of dry matter of the cFF-fed groups were greater with respect to control group and increased throughout the experimental period,whereas the ATTD of ether extract linearly decreased with increasing levels of cFF-fed groups compared with control group and throughout the experimental period(P<0.05).Additionally,a lin-ear increase in the heterophil to lymphocyte ratio,serum cholesterol,triglycerides and alanine-aminotransferase were observed with increasing dietary levels of cFF(P<0.05);however,no differences were observed in lipoprotein lipase or sterol regulatory element binding transcription factor gene abundance.Conclusions The results of this experiment demonstrate that it is possible to incorporate cFF into nutritionally balanced diets for broiler chickens,even up to 25%substitution levels,for up to 33 d without adversely impacting the overall growth performance of male broiler chickens raised under commercial conditions.Further studies are essential to validate the hematological trait findings.
文摘In petroleum extraction,the sealing surfaces of bolted joints are susceptible to damage due to the high-temperature and high-pressure conditions in wellbores.This damage adversely affects sealing performance,consequently leading to the failure and damage of threaded connections.In severe cases,it can result in considerable economic losses and trigger safety accidents.The sealing performance of special bolted joints holds crucial importance for production efficiency,output,equipment lifespan,and cost control.Enhancing the sealing perfor-mance of threaded connections can have a positive impact on industrial production and environmental protection.The existing research on American Petroleum Institute threaded joints has been thorough and has obtained a series of excellent results.However,the research on the sealing damage mechanism of threaded connections under complex well conditions lacks sufficient depth and that on new sealing technology is scarce.This study proposes a half-size evaluation test to address the abovementioned problem.Based on this test,an investigation into the sealing performance of threaded connections under high-temperature,cyclic loading,and high-temperature creep conditions is conducted.This study uses a combined approach of finite element methods and experiments to investigate the impact of different makeup torques on the sealing performance of premium threaded connections(PTCs).The results of the half-size evaluation test indicate that temperature notably influences the sealing performance of threaded connections.The continuous action of high temperatures causes contact pressure and sealing performance to decrease,and sealing contact pressure increases after cooling.Finite element and test results show that for a certain joint A,the greater the torque,the higher the critical sealing pressure of the thread,and the better the sealing performance.The research on the sealing damage mechanism of PTCs provides a scientific basis and theoretical guidance for the further optimization and development of PTCs.
基金financially supported by the National Natural Science Foundation of China(No.22075262)。
文摘Crude petroleum pollution causes some serious ecological disasters in the ocean.Marine sediment microbial fuel cells(MSMFCs)have been utilized as a novel method for in-situ degradation and a long-term power source.Herein,the effect of different concentrations of rhamnolipids biosurfactant on the electrochemical performance of MSMFCs anode and the higher efficiency of oil degradation are creatively investigated.The results indicate that the anode in sediment containing rhamnolipids effectively enriches the indigenous electrogenic Pseudophaeobacter and Pseudomonas,which significantly enhances the electrochemical performance of the MSMFCs.Under rhamnolipids at the concentration of 200 mg kg^(-1)in sediment,the anode specific capacitance(401.45 Fm^(-2)),exchange current density(4.87×10^(-2)mAm^(-2)),and cell maximum power density(140.24 mWm^(-2))increase by 2.50,38.65,and 2.11 times,respectively,in comparison with its natural sediment.And the oil degradation rate(40.06%)was higher than the blank(17.55%).It demonstrates that the synergistic effect between electrochemical catalytic degradation and emulsifying solubilization of rhamnolipids surfactant directly accelerates the degradation of petroleum in marine sediment,which will provide a novel method and theoretical guidance for in-situ degradation and efficient removal of crude petroleum on ocean floor.
