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中温和高温环境下乙酸和丙酸厌氧发酵产甲烷动力学特征

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农业工程学报 2018年第21期34卷 234-238页

作者：乔玮姜萌萌赵婧 Wandera s.m.董仁杰中国农业大学工学院北京100083 国家能源生物燃气高效制备及综合利用技术研发(实验)中心北京100083 中国农业大学烟台研究院烟台264670 荷兰格罗宁根大学科学与工程学院格罗宁根9747AG

采用不同浓度的乙酸和丙酸在中高温下进行厌氧发酵批次试验,采用修正的Gompertz模型和产甲烷的一级动力学模型分析,研究酸浓度和温度对发酵产气动力学的影响。研究表明,当乙酸和丙酸浓度较低时降解较快,高浓度酸抑制产气。乙酸在中温条... 详细信息

采用不同浓度的乙酸和丙酸在中高温下进行厌氧发酵批次试验,采用修正的Gompertz模型和产甲烷的一级动力学模型分析,研究酸浓度和温度对发酵产气动力学的影响。研究表明,当乙酸和丙酸浓度较低时降解较快,高浓度酸抑制产气。乙酸在中温条件下降解较快,质量浓度为5 000 mg/L时中温反应有最大产甲烷速率101 mL/d;质量浓度为10 000mg/L时高温条件下有最大产甲烷速率77mL/d,随酸浓度增加,最大产甲烷速率减小,高温反应器对酸的耐受度较高。丙酸在高温条件下更易降解,浓度为4 000 mg/L时,中高温反应均有最大产气速率:78 mL/d(中温)和96 mL/d(高温)。另外,高浓度乙酸和丙酸厌氧降解产气具有滞后性,且随酸浓度的增加滞后期延长,降解过程受到抑制,一级动力学常数减小。温度对厌氧降解的影响大于酸浓度对厌氧降解的影响。

关键词：甲烷动力学温度厌氧发酵乙酸丙酸

Effect of Injection Velocity on structure Part Characteristic in A50 Die Casting Process with High Vacuum system

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Journal of materials science & Technology 2008年第1期24卷 75-79页

作者： s.m.Lee P.K.seo C.G.Kang school of mechanical Engineering Pusan National University Busan 609-735 Korea

When diecasting large and thin mg alloy parts.m.terial defects occur,which include porosity,nonuniform mechanical properties,irregular surfaces,and incomplete *** resolve these problems,it is necessary to have uniform injection velocities and temperatures as well as control the *** study investigated the feasibility of producing large and thin components using a die caster by attaching a high vacuum *** particular,the effects of injection velocity on surface quality and the mechanical properties of the products were ***,an injection velocity scheme and a die structure capable of casting in a vacuum were *** a result,it was found that the critical low injection velocity was 0.2 m/s to produce large thin mg alloy structures having good mechanical properties.

关键词： mg die casting Injection velocity Vacuum system

Instability inspection of parametric vibrating rectangular mindlin plates lying on Winkler foundations under periodic loading of moving masses

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Acta mechanica sinica 2019年第1期35卷 242-263,I0007页

作者： E.Torkan m.Pirmoradian m.Hashemian Young Researchers and Elite Club Khomeinishahr Branch Islamic Azad UniversityKhomeinishahrIsfahan 84175-119Iran Department of mechanical Engineering Khomeinishahr BranchIslamic Azad UniversityKhomeinishahrIsfahan 84175-119Iran

Parametric resonance is one of the most important issues in the study of dynamical behavior of structures. In this paper, dynamic instability of a moderately thick rectangular plate on an elastic foundation is investigated in the case of parametric and external resonances due to periodic passage of moving masses. The governing coupled partial differential equations (PDEs) of the system, with consideration of the first-order shear deformation theory (FsDT) or mindlin plate theory, are presented and they are reduced to a set of ordinary differential equations (ODEs) with time-dependent coefficients using the Galerkin procedure. All inertial components of the moving masses are adopted in the dynamical formulation. Instability survey is carried out for three different loading trajectories considerably interested in many practical applications of the issue, i.e. rectilinear, diagonal and orbiting trajectories. In order to analyze the resonance conditions, the incremental harmonic balance (IHB) method is introduced to calculate instability boundaries, as well as external resonance curves in parameters plane. A comprehensive study is done to assess effects of thickness ratio and foundation stiffness on the resonance conditions. It is found that an increase in the plate's thickness ratio leads to a reduction in values of critical parameters. moreover, it is observed that in creasing the foundation stiffness.m.ves the in stability regions and resona nee curves to higher frequencies of the moving masses and also leads to further stability of the parametrically excited system at lower frequencies. Time response s.m.lations done via Runge-Kutta method confirmed the results predicted by IHB method.

关键词： mass-plate interaction mindlin plate Parametric resonance External resonance Incremental harmonic balanee method

Fine mapping of genomic regions associated with female fertility in Nellore beef cattle based on sequence variants from segregating sires

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Journal of Animal science and Biotechnology 2020年第2期11卷 303-315页

作者： Gerson A.Oliveira Júnior Daniel J.A.santos Aline s.m.Cesar solomon A.Boison Ricardo V.Ventura Bruno C.Perez JoséF.Garcia JoséBento s.Ferraz Dorian J.Garrick Department of Veterinary medicine University of São Paulo(USP)Faculty of Animal Science and Food EngineerPirassunungaSPBrazil Department of Animal Bioscience Center for Genetic Improvement of LivestockUniversity of GuelphGuelphONCanada Department of Animal and Avian sciences University of MarylandCollege ParkMarylandUSA Department of Animal science University of São Paulo(USP)PiracicabaSPBrazil Department of sustainable Agricultural systems University of Natural Resources and Life SciencesViennaAustria Department of Animal Nutrition and Production School of Veterinary Medicine and Animal ScienceUniversity of São Paulo(USP)PirassunungaBrazil Department of support Production and Animal HealthSchool of Veterinary MedicineSão Paulo State University(Unesp)AraçatubaSPBrazil school of Agriculture Massey UniversityRuakura Ag CentreHamiltonNew Zealand

Background:Impaired fertility in cattle limits the efficiency of livestock production *** the genetic architecture of fertility traits would facilitate their improvement by *** this study,we characterized sNP chip haplotypes at QTL blocks then used whole-genome sequencing to fine map genomic regions associated with reproduction in a population of Nellore(Bos indicus)***:The dataset comprised of 1337 heifers genotyped using a Geneseek®Genomic Profiler panel(74677 sNPs),representing the daughters from 78 *** performing marker quality control,64800 sNPs were *** carried by each sire at six previously identified QTL on BTAs 5,14 and 18 for heifer pregnancy and BTAs 8,11 and 22 for antral follicle count were constructed using findhap *** significance of the contrasts between the effects of every two paternally-inherited haplotype alleles were used to identify sires that were heterozygous at each ***-genome sequencing data localized to the haplotypes from six sires and 20 other ancestors were used to identify sequence variants that were concordant with the haplotype *** analyses were applied to these variants using KEGG and mesH ***:A total of six(BTA 5),six(BTA 14)and five(BTA 18)sires were heterozygous for heifer pregnancy QTL whereas six(BTA 8),fourteen(BTA 11),and five(BTA 22)sires were heterozygous for number of antral follicles’*** to inadequate representation of many haplotype alleles in the sequenced animals,fine mapping analysis could only be reliably performed for the QTL on BTA 5 and 14,which had 641 and 3733 concordant candidate sequence variants,*** KEGG“Circadian rhythm”and“Neurotrophin signaling pathway”were significantly associated with the genes in the QTL on BTA 5 whereas 32 mesH terms were associated with the QTL on BTA *** the concordant sequence variants,0.2%and 0.3%were classified as.m.ssense variants for BTAs 5 and 14,respe

关键词： Antral follicles Causal variants Haplotype Heifer pregnancy WGs

Thermo-magnetic analysis of thick-walled spherical pressure vessels.m.de of functionally graded materials

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Applied mathematics and mechanics(English Edition) 2019年第6期40卷 751-766页

作者： m. A. NEmATOLLAHI A. DINI m. HOssEINI Department of Biosystems Engineering College of AgricultureShiraz UniversityShiraz 71441-65186Iran Department of mechanical Engineering Ferdowsi University of MashhadMashhad 91775-1111Iran Department of mechanical Engineering Sirjan University of TechnologySirjan 78137-33385Iran

This study presents an analytical solution of thermal and mechanical displacements, strains, and stresses for a thick-walled rotating spherical pressure vessel made of functionally graded materials (FGms). The pressure vessel is subject to axis.m.etric mechanical and thermal loadings within a uniform magnetic field. The material properties of the FGm are considered as the power-law distribution along the thickness. Navier’s equation, which is a second-order ordinary differential equation, is derived from the mechanical equilibrium equation with the consideration of the thermal stresses and the Lorentz force resulting from the magnetic field. The distributions of the displacement, strains, and stresses are determined by the exact solution to Navier’s equation. Numerical results clarify the influence of the thermal loading, magnetic field, non-homogeneity constant, internal pressure, and angular velocity on the magneto-thermo-elastic response of the functionally graded spherical vessel. It is observed that these parameters have remarkable effects on the distributions of radial displacement, radial and circumferential strains, and radial and circumferential stresses.

关键词： analytical solution magnetic field thermal loading rotating thick-walled spherical pressure vessel functionally graded material (FGm)

Grass-Root Coaches Knowledge, Understanding, Attitude And Confidence to Deliver Injury Prevention Training in Youth soccer: a Comparison of Coaches in Three EU Countries

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Journal of science in sport and Exercise 2020年第4期2卷 367-374页

作者： mark De ste Croix F.Ayala s.Hernandez sanchez m.Lehnert J.Hughes school of sport and Exercise University of GloucestershireCheltenham GL502RHUK Department of sport sciences Sport Research CentreMiguel Hernandez University of ElcheElche 03202Spain Department of Pathology and surgery Physiotherapy Area Miguel Hernandez University of ElcheElche 03202Spain Department of sport and Physical Culture Palacky UniversityOlomouc 77200Czech Republic

Purpose It is well recognised that injury prevention training can reduce injury incidence,however current coach education pathways do not provide grass-root coaches with the knowledge and confidence to deliver such training to youth *** aim of this study was to explore differences in knowledge,understanding,attitude and confidence to deliver such injury prevention training in three European *** A total of 269 grass-root soccer coaches from 3 European countries(Czech Republic,UK,spain)were recruited for this study.A validated questionnaire exploring knowledge,understanding,attitude towards and confidence to deliver youth injury prevention training was completed prior to a 2 h workshop on injury prevention *** between countries was examined using Bayesian factors to quantify the evidence for and against the hypothesis of independence(H0)by ass.m.ng a Poisson s.m.ling scheme(as there was no a priori restriction on any cell count,nor on the grand total)(BF10 Poisson).Results Current knowledge,attitude and confidence to deliver injury prevention training to youth players was poor across all three European *** few coaches were currently using injury prevention training in their coaching sessions(23%).There were s.m. country specific differences for attitude towards injury prevention training and confidence to deliver injury training,with spanish coaches reporting a more positive attitude and confidence to deliver such *** fewer coaches in the UK were using injury prevention training compared to coaches in spain and the Czech *** As coaches identified a need for coach education and few were delivering injury prevention training,there is a clear need to embed and implement this programme into the grassroots coaching framework of sports governing bodies to improve adoption,implementation and maintenance.

关键词： Youth Injury prevention training Coach education movement competency

Two-fluid modeling of Geldart A particles in gas-fluidized beds

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Particuology 2008年第6期6卷 540-548页

作者： m.A. van der Hoef J.A.m. Kuipers Faculty of science & Technology University of Twente

We have investigated the effect of cohesion and drag models on the bed hydrodynamics of Geldart A particles based on the two-fluid （TF） model. For a high gas velocity U0 = 0.03 m/s, we found a transition from the homogeneous fluidization to bubbling fluidization with an increase of the coefficient C1, which is used to account for the contribution of cohesion to the excess compressibility. Thus cohesion can play a role in the bed expansion of Geldart A particles. Apart from cohesion, we have also investigated the influence of the drag models. When using the Wen and Yu drag correlation with an exponent n = 4.65, we find an under-prediction of the bed expansion at low gas velocities （U0 = 0.009 m/s）. When using a larger exponent （n = 9.6）, as reported in experimental studies of gas-fluidization, a much better agreement with the experimental bed expansion is obtained. These findings suggest that at low gas velocity, a scale-down of the commonly used drag model is required. On the other hand, a scale-up of the commonly used drag model is necessary at high gas velocity （U0 = 0.2 and 0.06 m/s）. We therefore conclude that scaling the drag force represent only an ad hoc way of repairing the deficiencies of the TF model, and that a far more detailed study is required into the origin of the failure of the TF model for s.m.lating fluidized beds of fine powders.

关键词： Gas-fluidized bed Geldart A particles Two-fluid model Cohesive force Drag correlation

The German Language:Alive or Dead?

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佛山科学技术学院学报(社会科学版) 1988年第3期 50-51页

作者： James Odell m·s

The German language is spoken by more than 118 million people *** is the national language of the Federal Republic of Germany(West Germany),the German Democratic Republic(East Germany),Austria and switzerland, to onlyname a few. It is called by s.m. to be "modern Latin", because its grammaticalcomplexities are s.m.lar to those found in *** fact,German is derived fromthe Teutonic languages,not Latin.

关键词： German spoken Republic Federal Latin speaking schools devoted opinion spanish

Optimization of Casting Process for Heat and Abrasion Resistant Large Gray Iron Castings

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Tsinghua science and Technology 2008年第2期13卷 152-156页

作者： s. m. Yoo Y. s. Cho C. C. Lee J. H. Kim C. H. Kim J. K. Choi Center for E-Design Korea Institute of Industrial Technology Kwanghee Casting mfg. Co. R&D Center Doosan Engine Co. Ltd.

Numerical s.m.lations were used to optimize the casting design and conditions for large cast iron castings for marine engines, s.m.lations of the mold filling and solidification sequences were used to analyze the problems of previous casting conditions with marked improvements for large cylinder liner parts, The amount and positions of chills were optimized to improve the mechanical properties and to minimize the shrinkage and micro porosity in the castings. Ultra sonic testing, penetration testing, and mechanical property testing show no defects in the castings with the productivity significantly increased.

关键词： gray cast iron numerical s.m.lation marine engine cylinder liner chill casting design optimization