检索结果-南通市图书馆

Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO_(2)fracturing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Particuology 2024年第7期90卷 149-163页

作者： Boyu Liu jun Yao Research Center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266000China

The non-uniform temperature distribution in supercritical CO_(2)(Sc-CO_(2))fracturing influences the density,viscosity,and volume expansion or shrinkage rate of Sc-CO_(2),impacting proppant *** study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall,proppant-fluid,and fluid-wall on the fluid and proppant temperature *** Sc-CO_(2)volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO_(2)*** factors,including proppant size,shape,thermal conductivity,concentration,temperature difference,and injection velocity,are carefully analyzed to elucidate their *** findings elucidate the existence of four distinct zones in the fluid temperature *** zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant *** fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity(governing the heating duration),the temperature difference between fluid and formation(impacting the magnitude of heat flux),and the proppant bed shape(controlling the effective heating area).Additionally,the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B,showing a strong correlation with proppant thermal conductivity,proppant size,injection velocity,and temperature *** proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

关键词： CFD-DEM Heat transfer Compressible fluid CO_(2)sequestration Proppant transport

Geometric Error Identification of Gantry-Type CNC Machine Tool Based on Multi-Station Synchronization Laser Tracers

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第2期37卷 150-162页

作者： jun Zha Huijie Zhang School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China Xi’an Jiaotong University Suzhou Academy Suzhou 215123China

Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial *** propose a geometric error identification method based on multi-station synchronization laser tracers to enable the rapid and high-precision measurement of geometric errors for gantry-type computer numerical control(CNC)machine *** method also improves on the existing measurement efficiency issues in the single-base station measurement method and multi-base station time-sharing measurement *** consider a three-axis gantry-type CNC machine tool,and the geometric error mathematical model is derived and established based on the combination of screw theory and a topological analysis of the machine kinematic *** four-station laser tracers position and measurement points are realized based on the multi-point positioning principle.A self-calibration algorithm is proposed for the coordinate calibration process of a laser tracer using the Levenberg-Marquardt nonlinear least squares method,and the geometric error is solved using Taylor’s first-order linearization *** experimental results show that the geometric error calculated based on this modeling method is comparable to the results from the Etalon laser *** a volume of 800 mm×1000 mm×350 mm,the maximum differences of the linear,angular,and spatial position errors were 2.0μm,2.7μrad,and 12.0μm,respectively,which verifies the accuracy of the proposed *** research proposes a modeling method for the precise measurement of errors in machine tools,and the applied nature of this study also makes it relevant both to researchers and those in the industrial sector.

关键词： Multi-point positioning Multi-station synchronization CNC machine tool Geometric error Error separation

A generalized presentation of multi-caloric effects based on exterior derivative theory and its applications

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第8期76卷 156-163页

作者： jun Yin School of Materials Science and Engineering Nankai UniversityTianjin 300350China School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108China

The emerging concept of multi-caloric effects, introduced in 2010, entails the application of multiple interplay fields to a thermodynamic system. While multi-caloric effects are the main focus of experimental endeavors, theoretical considerations fall short of providing a thorough understanding. This paper introduces a comprehensive presentation on multi-caloric effects,employing the method and theory of exterior derivative formations. It addresses every aspect of thermodynamic systems, showcasing its applicability to multi-caloric materials(both singlephase and multi-phase materials), and its adaptability to different scenarios(either in single or multiple force fields). The formulation of Maxwell relationships, characterized by their generality and universality, enables a clear prediction in entropy and temperature, facilitating a distinct identification between independent and interdependent contributions from multi-caloric effects. These insights hold significant importance in designing and developing specialized thermodynamic materials, optimizing functional performances and exploring innovative mechanisms.

关键词： multicaloric effects Maxwell relations isothermal entropy adiabatic temperature

On the Monge–Kantorovich Mass Transfer Problem in Higher Dimensions

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第8期40卷 1989-2004页

作者： Xiao jun LU School of Mathematics Southeast UniversityNanjing 210096P.R.China

This paper mainly investigates the approximation of a global maximizer of the Monge–Kantorovich mass transfer problem in higher dimensions through the approach of nonlinear partial differential equations with Dirichlet *** an approximation mechanism,the primal maximization problem can be transformed into a sequence of minimization *** applying the systematic canonical duality theory,one is able to derive a sequence of analytic solutions for the minimization *** the final analysis,the convergence of the sequence to an analytical global maximizer of the primal Monge–Kantorovich problem will be demonstrated.

关键词： Monge-Kantorovich mass transfer singular variational problem canonical duality theory

Low-protein diet supplemented with 1% L-glutamine improves growth performance, serum biochemistry, redox status, plasma amino acids, and alters fecal microbiota in weaned piglets

在线全文

学校读者我要写书评

暂无评论

Animal Nutrition 2024年第2期17卷 144-154页

作者： jun Li jun Bai Ying Yang Zhenlong Wu State Key Laboratory of Animal Nutrition and Feeding Department of Companion Animal Science China Agricultural University

Glutamine, one of the most abundant amino acids in the body, has been shown to exert various beneficial effects in pigs. However, knowledge regarding the role of dietary glutamine in low-protein diet-fed piglets remains scarce. The present study aimed to investigate the effects of different levels of L-glutamine on growth performance, serum biochemistry parameters, redox status, amino acids, and fecal microbiota in low-protein diet-fed piglets. A total of 128 healthy crossbred piglets(Landrace × Yorkshire)were randomly allocated into 4 groups of 4 replicate pens, with 8 piglets per pen. Piglets in the 4 groups were fed with corn and soybean meal-based low-protein diets(crude protein level, 17%) that contained0%, 1%, 2%, and 3% L-glutamine, respectively, for 28 d. Pigs administered 1% L-glutamine had greater body weight on d 28 and average daily gain(ADG, P < 0.01), whereas a lower feed to gain ratio(F:G) from d 1to 28(P < 0.01), compared to the other three groups. Besides, lower body weight on d 14 and 28, ADG,average daily feed intake, and higher F:G from d 15 to 28 and d 1 to 28 were observed in response to 2%and 3% L-glutamine treatments than 0% and 1% L-glutamine treatments(P < 0.01). Moreover, 1% Lglutamine reduced serum glucose, malondialdehyde, hydrogen peroxide concentrations and inhibited aspartate aminotransferase, alanine aminotransferase, myeloperoxidase activities in low-protein diet-fed piglets on d 14, with concomitantly upregulated catalase, total superoxide dismutase activities and glutathione level(P < 0.05). However, dietary 3% L-glutamine enhanced blood urea nitrogen content in pigs on d 14(P < 0.05). Further investigation revealed that 1% L-glutamine upregulated the serum glutamine, lysine, methionine, tyrosine, and reduced plasma valine content(P < 0.05). Additionally, 1% Lglutamine upregulated the abundance of p＿75＿a5, Clostridium, Lactobacillus, Prevotellaceae＿Prevotella,and Gemmiger in the stool of piglets on d 14, with the Streptococcus lev

关键词： Glutamine Low protein diet Pig Redox status Amino acid Microbiota

Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第1期38卷 93-103页

作者： WANG Zhao-jun SUI Ti-ti ZHANG Chi PAN jun-ning Key Laboratory of Port Waterway and Sedimentation Engineering of the Ministry of TransportNanjing Hydraulic Research InstituteNanjing 210024China Key Laboratory of Coastal Disaster and Protection(Hohai University) Ministry of EducationNanjing 210098China The National Key Laboratory of Water Disaster Prevention Nanjing 210098China

The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal *** this study,an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed *** liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed *** on the 2D full dynamic model of wave-induced seabed response,a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed ***,new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear *** indicate that(1)Due to the influence of wave nonlinearity,the vertical transmission of negative pore water pressure in the seabed is hindered,and therefore,the amplitude decreases significantly.(2)In general,with the increase of wave nonlinearity,the liquefaction depth of seabed decreases *** under asymmetric and skewed wave loading,the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave ***,highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave.(3)The asymmetry of wave pressure leads to the increase of liquefaction width,whereas the influence of skewedness is not significant.(4)Compared with the nonlinear waveform,seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading.

关键词： nonlinear wave seabed response seabed liquefaction numerical simulation liquefaction prediction

Spectral Fittings of Warm Coronal Radiation with High Seed Photon Temperature:Apparent Low-temperature and Flat Soft Excess in AGNs

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第7期24卷 135-144页

作者： Ze-Yuan Tang jun-Jie Feng jun-Hui Fan School of Mathematics and Information Science Guangzhou UniversityGuangzhou 510006China Center for Astrophysics Guangzhou UniversityGuangzhou 510006China Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province Guangzhou 510006China Key Laboratory for Astronomical Observation and Technology of Guangzhou Guangzhou 510006China

A warm corona has been widely proposed to explain the soft excess(SE)in X-ray above the 2-10 ke V power law extrapolation in Active Galactic Nuclei(AGNs).In actual spectral fittings,the warm coronal seed photon temperature(T_s)is usually assumed to be far away from the soft X-ray,but kT_scan reach close to 0.1 ke V in the standard accretion disk *** this study,we used Monte Carlo simulations to obtain radiation spectra from a slab-like warm corona and fitted the spectra using the spherical-geometry-based routine THCOMP or a thermal *** findings reveal tha high T_scan influence the fitting results.A moderately high kT_s(around 0.03 ke V)can result in an apparent low-temperature and flat SE,while an extremely high kT_s(around 0.07 ke V)can even produce an unobserved blackbody-like *** conclusions indicate that,for spectral fittings of the warm coronal radiation(SE in AGNs),kT_sshould be treated as a free parameter with an upper limit,and an accurate coronal geometry is necessary when kT_s>0.01 ke V.

关键词： galaxies active-accretion-accretion disks-black hole physics

Survey on performance of vertical slot and nature-like fishways at Angu hydropower station, Southwest China

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2024年第1期17卷 83-91页

作者： jun-jian Sun Jia-yue Shi Qi Zhang Xiao-tao Shi jun-jun Tan PowerChina Huadong Engineering Corporation Limited Hangzhou 311122China Hubei International Science and Technology Cooperation Base of Fish Passage China Three Gorges UniversityYichang 443002China

To restore dam-blocked natural fish migratory passages,a growing number of artificial fishways have been built in water conservancy and hydropower projects in *** Angu hydropower station involved diverse important fish habitats in the lower reaches of the Daduhe River in Southwest ***,a vertical slot fishway(VSF)and a nature-like fishway(NLF)were built near the backwater area of the reservoir to connect the upstream and downstream *** and aquatic ecological surveys were conducted after the completion of the project to estimate the fish passing effect of the two *** results indicated that both fishways were in effective operation and could maintain the desired hydrodynamic conditions and be used by several local fish *** the survey,149 fish from 15 species and 111 fish from 17 species were captured by the traps in the VSF and NLF,respectively,while 1263 fish from 27 species were found in the downstream *** species captured in the VSF were not found in the NLF,and vice versa,which implied the different preferences of ***,3789 signals including 2099 upward ones and 1690 downward ones were monitored with an ultrasonic fish detector at the inlet of the *** findings revealed the characteristics of fish species observed in and near the fishways and provided valuable insights into the different fish passing capabilities of VSFandNLF.

关键词： Vertical slot fishway Nature-like fishway Aguatic ecological survey Fishwaymonitoring Statistical analysis

Pretreating and normalizing metabolomics data for statistical analysis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Genes & Diseases 2024年第3期11卷 188-205页

作者： jun Sun Yinglin Xia Division of Gastroenterology and Hepatology Department of MedicineDepartment of Microbiology/ImmunologyUIC Cancer CenterUniversity of Illinois ChicagoJesse Brown VA Medical Center Chicago(537)ChicagoIL 60612USA Division of Gastroenterology and Hepatology Department of MedicineUniversity of Illinois ChicagoChicagoIL 60612USA

Metabolomics as a research field and a set of techniques is to study the entire small molecules in biological *** is emerging as a powerful tool generally for pre-cision ***,integration of microbiome and metabolome has revealed the mechanism and functionality of microbiome in human health and ***,metabo-lomics data are very ***/pretreating and normalizing procedures on metabolomics data are usually required before statistical *** this review article,we comprehensively review various methods that are used to preprocess and pretreat metabolo-mics data,including MS-based data and NMR-based data preprocessing,dealing with zero and/or missing values and detecting outliers,data normalization,data centering and scaling,data *** discuss the advantages and limitations of each *** choice for a suitable preprocessing method is determined by the biological hypothesis,the characteristics of the data set,and the selected statistical data analysis *** then provide the perspective of their applications in the microbiome and metabolome research.

关键词： Data centering and scaling Data normalization Data transformation Missing values MS-Baseddata preprocessing NMRData preprocessing Outliers Preprocessing/pretreatment