Showing papers by "Xuzhou Institute of Technology published in 2009"

Experimental study on the mechanical properties of rocks at high temperature

Abstract: The mechanical properties of marble, limestone, and sandstone as well as the stress-strain curve, the varying characteristics of the peak strength, the peak strain and elastic modulus were studied by using the MTS810 Rock Mechanics Servo-controlled Testing System under the action of temperatures rang-ing from room temperature to 800℃. Results show that (1) the peak strength and elastic modulus of marble fluctuate at the temperature from normal to 400℃; and they decrease gradually over 400℃. (2) With the rise of the temperature, the peak strength and elastic modulus of limestone show downward trend from normal temperature to 200℃; have little change from 200℃ to 600℃; and decrease sharply over 600℃. (3) The peak strength of sandstone shows a downward trend while a little change for elastic modulus at normal temperature to 200℃; and from 200℃ to 600℃, the peak strength of sandstone in-creases while a little change for elastic modulus; the peak strength and elastic modulus decrease rap-idly at the temperature over 600℃. (4) The peak strain of limestone shows little change at normal tem-perature to 600℃, however, the peak strain increases rapidly over 600℃; and for marble and sandstone, the peak strain decreases with the rise of the temperature from normal temperature to 200℃, the peak strain increases rapidly over 200℃. The result can provide valuable references for the rock engineering design at high temperature.

Properties of failure mode and thermal damage for limestone at high temperature

Abstract: The mechanical properties of limestone such as the stress-strain curve, the variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the action of temperatures ranging from room temperature to 800 °C. Our results show that: 1) the temperature has not clear effect on the mechanical properties of limestone from room temperature to 600 °C. However, the mechanical properties of limestone deteriorate rapidly when the temperature is above 600 °C. In this case, the peak stress and modulus of elasticity decrease rapidly. When the temperature reaches 800 °C, the entire process, showing the stress-strain curve is displayed indicating an obvious state of plastic-deformation; 2) the failure mode of limestone shows the breakdown of tensile strength from room temperature to 600 °C, as well as the compress shearing damage over 600 °C; 3) combining our test results with the concept of thermal damage, a thermal damage equation was derived.

Identification, characterization, and molecular application of a virulence-associated autotransporter from a pathogenic Pseudomonas fluorescens strain.

Abstract: A gene, pfa1, encoding an autotransporter was cloned from a pathogenic Pseudomonas fluorescens strain, TSS, isolated from diseased fish. The expression of pfa1 is enhanced during infection and is regulated by growth phase and growth conditions. Mutation of pfa1 significantly attenuates the overall bacterial virulence of TSS and impairs the abilities of TSS in biofilm production, interaction with host cells, modulation of host immune responses, and dissemination in host blood. The putative protein encoded by pfa1 is 1,242 amino acids in length and characterized by the presence of three functional domains that are typical for autotransporters. The passenger domain of PfaI contains a putative serine protease (Pap) that exhibits apparent proteolytic activity when expressed in and purified from Escherichia coli as a recombinant protein. Consistent with the important role played by PfaI in bacterial virulence, purified recombinant Pap has a profound cytotoxic effect on cultured fish cells. Enzymatic analysis showed that recombinant Pap is relatively heat stable and has an optimal temperature and pH of 50 degrees C and pH 8.0. The domains of PfaI that are essential to autotransporting activity were localized, and on the basis of this, a PfaI-based autodisplay system (named AT1) was engineered to facilitate the insertion and transport of heterologous proteins. When expressed in E. coli, AT1 was able to deliver an integrated Edwardsiella tarda immunogen (Et18) onto the surface of bacterial cells. Compared to purified recombinant Et18, Et18 displayed by E. coli via AT1 induced significantly enhanced immunoprotection.

An ab initio and density functional theory study on the mechanism for the reaction of OH with 2-ethylfuran

Abstract: The mechanism of the reaction of OH + 2-ethylfuran has been investigated using the G3MP2 and G3MP2B3 levels of theory. The geometric parameters of all species involved in the reaction have been optimized at the MP2 and B3LYP levels of theory with 6-311G(d,p) basis set. The overall profile of doublet potential energy surface (PES) for the OH + 2-ethylfuran reaction has been constructed using the G3MP2 and G3MP2B3 methods. The results show that the addition-elimination mechanism dominates the OH + 2-ethylfuran reaction and the major products are CH3CH2C(OH)CHCHCHOH (P8) and CH3CH2COCHCHCHOH (P6).

Optimization of PID parameters based on genetic algorithm and interval algorithm

Abstract: To overcome simple genetic algorithm's defects of worse local searching ability and premature convergence, a hybrid algorithm of genetic algorithm and interval algorithm was proposed, and applied to parameters optimization of PID controller by employing interval algorithm in population initialization of genetic algorithm. The simulation and experimental results show that the new algorithm is better than simple genetic algorithm, which can improve the convergence speed, overcome the premature convergence phenomena, reduce the influence of random initial population, improve the convergence precision, and has excellent convergence performance and optimization ability.

Positive Solution to a Singular -Laplacian BVP with Sign-Changing Nonlinearity Involving Derivative on Time Scales

Abstract: Let be a time scale such that . By using a monotone iterative method, we present some existence criteria for positive solution of a multiple point general Dirichlet-Robin BVP on time scales with the singular sign-changing nonlinearity. These results are even new for the corresponding differential and difference equation as well as in general time scales setting. As an application, an example is given to illustrate the results. The interesting point here is that the sign-changing nonlinear term is involved with the first-order derivative explicitly, and the singularity may occur at , , and .

Stability of Bifurcated Periodic Solutions in a Delayed Competition System with Diffusion Effects

Abstract: In this paper, a delayed Lotka—Volterra two species competition diffusion system with a single discrete delay and subject to the homogeneous Dirichlet boundary conditions is considered. By applying the normal form theory and the center manifold reduction for partial functional differential equations (PFDEs), the stability of bifurcated periodic solutions occurring through Hopf bifurcations is studied. It is shown that the bifurcated periodic solution occurring at the first bifurcation point is orbitally asymptotically stable on the center manifold while those occurring at other bifurcation points are unstable. Finally, some numerical simulations to a special example are included to verify our theoretical predictions.

Enhanced continuous-variable entanglement by a pair of nonlinearly coupled waveguides

Abstract: We seek to analyze a three-level cascade laser with a pair of nonlinearly coupled waveguides inside the cavity. Applying the pertinent master equation, we investigate the squeezing and entanglement properties intracavity produced by our system. It is shown that with the help of nonlinearly coupled waveguides highly squeezed as well as macroscopic entangled light with high intensity can be achieved.

Integral-type operators from weighted Bloch spaces into Bergman-type spaces

Abstract: Let ϕ be an analytic self-map and u be a fixed analytic function on the open unit disk 𝔻 in the complex plane ℂ. The following integral-type operators have recently attracted a lot of attention. In this article, we characterize the boundedness and compactness of operators I g and J g from weighted Bloch spaces into Bergman-type spaces.

Existence of Positive Solutions to Singular -Laplacian General Dirichlet Boundary Value Problems with Sign Changing Nonlinearity

Abstract: By using the well-known Schauder fixed point theorem and upper and lower solution method, we present some existence criteria for positive solution of an 𝑚-point singular 𝑝-Laplacian dynamic equation on time scales with the sign changing nonlinearity. These results are new even for the corresponding differential (𝕋=ℝ) and difference equations (𝕋=ℤ), as well as in general time scales setting. As an application, an example is given to illustrate the results.

Volterra-type composition operators from logarithmic Bloch spaces into Bloch-type spaces

Abstract: Let φ be an analytic self-map of the unit disk D,H(D)the space of analytic functions on D and g∈H(D)The boundedness of the Volterra-type composition operators from the logarithmic Bloch spaces into the Bloch-type spaces are investigated in this paper

Multi-agent Assessment on Marketing Risk Based on Evidence Theory

Abstract: The paper aims to solving the problems on risk assessment in process of marketing through basic principles of evidence theory. First of all, the concept model on risk assessment based on evidence theory is established; then set agent parameters of marketing risk of a certain tinned beer, and establish the corresponding fuzzy membership function according to the marketing characteristics of this tinned beer; finally, the synthesis rule of evidence theory is converted into synthesis rule of fuzzy evidence so as to achieve the combination between fuzzy function and membership function and form the ultimate multi-agent assessment mathematical model. Input actual monitoring data into the model, and the results show that multi-agent assessment on marketing risk model established in this paper could well conduct the comprehensive assessment for marketing conditions of the tinned beer, and it also shows that it is an effective way for solving the issue of marketing risk assessment by using the model, which could provide support for decision-makers.

2-(2-Chloro-phen-yl)-2,3-dihydro-quinazolin-4(1H)-one.

Abstract: The title compound, C14H11ClN2O, was synthesized by the reaction of 2-chloro­benzaldehyde and 2-amino­benzamide in an ionic liquid The pyrimidine ring adopts a skew-boat conformation and the two benzene rings make a dihedral angle of 871 (1)° In the crystal, N—H⋯O and C—H⋯N hydrogen bonding links the mol­ecules along b

A novel design method to reduce the impact between ball and re-circulating mechanism in ball screws

Abstract: In high-speed/high-precision ball screw transmitting systems, the re-circulating mechanism of ball screws is used for providing the path for steel balls rolling in screw grooves generally Because the rotating speed of the driven shaft in the mechanism has become higher and higher, forces caused by the impact activity between the steel ball and re-circulating mechanism has resulted in a series of troublesome problems, such as violent vibration, strong noise, and damage to the recirculating mechanism after some significant service times, etc In order to reduce the impact, a novel method using elastic joint between re-circulating mechanism and nut is proposed and the influence of joint rigidity on impact force is discussed The conclusion is made that the impact force using rigid joint is always higher than that using elastic joint, and the influence degree of joint rigidity on the impact force is affected by the mass radio of steel ball and re-circulating mechanism The experimental results show that using elastic joint between re-circulating mechanism and nut can reduce the impact force effectively

Research on the stabilization of friction torque of precision ball screw

Abstract: Taking into account the influence of the error in the contact points of balls and the groove on the contact force, the influence of manufacturing errors of grooves on friction torque was analyzed. The view that the manufacturing errors of groove in ball screw mechanism affect the value of the friction torque averagely was brought forward. The characteristic of fiction torque of three type ball screws included inner-return type, return pipe type and end cap type was investigated through the friction torque test. The influence of lubrication on the stabilization of fiction torque of ball screw was also investigated through the tests. It was found that the fluctuation of the friction torque at the normal frequency of 1Hz could be eliminated completely when the ball screw mechanism is lubricated by grease. Analysis indicates that the fluctuation of the friction torque at the normal frequency of 1Hz is resulted from the jam and fall off of balls because of poor lubrication.

Prediction of quantity of water inrush from coal seam floor and its reinforcement technique by grouting

Abstract: Based on the Chezy rule,which can describe crack water flow of bedrock,the mathematical model of confined aquifer is set up;and the formulae of water flow and water inrush according to Lagrangian method and Bernoulli energy equation are deduced.Calculating results indicate that the error of computed water inrush and actual in-situ water inrush is only 1.04%.Aiming at the situation of water from flooding to floor of coal seam at a majority of coal mines in Jiaozuo mining area,the method of reinforcement of floor aquifer by grouting to prevent water inrush disasters is put forward.The grouting holes are mainly arranged according to developing extent of fractures and its directions on the strike;and the spaces between grouting holes are determined by diffusing radius of grouting.Grouting parameters such as grouting pressure and grouting quantity are also analyzed;and high pressure water-stopping device is manufactured,which can solve the problem of water-stopping in advancing flow at grouting hole.

A Review of China's Second Language Writing Research in the Past 18 Years(1991-2008)

Abstract: A survey on articles concerning second language writing (SLW) in China,as published in eight of the core linguistic journals in the past 18 years,shows that the domestic research of SLW presents characteristics of scientific,poly-faceted and rational development. It is proposed that future studies on SLW focus more on the use of multimedia programs designed to take more empirical research on what influence the learning environment can put on learners.

Information storage and extraction between atoms and cavities

Abstract: In this paper, we present a scheme to transfer quantum information between atomic qubits and continuous-variable systems. The information carried by atomic qubits can be stored in cavity fields by introducing classical fields, and the deposited information can also be retrieved from the cavity fields to the atomic qubits by turning off the classical fields.

Nanocrystals of Co2+‐Doped MgGa2O4: Preparation by a Low‐Temperature Combustion Method and Optical Properties

Abstract: Co 2+ -doped MgGa 2 O 4 nanocrystals were prepared at 500 °C by a low-temperature combustion method without any further calcination. Powder X-ray diffraction (XRD) indicated that the only crystalline phase in the product was MgGa 2 O 4 with a grain size of 33-36 nm. Scanning electron microscopy (SEM) showed that the products contained pores formed by the gases evolved during the combustion reaction. The excitation and emission spectra of the nanocrystalline powders in the visible and near infrared regions were characteristic of tetrahedral Co 2+ ions, suggesting that Co 2+ ions replaced tetrahedral Mg 2+ ions in the MgGa 2 0 4 crystals. We assigned the visible and near infrared luminescent bands to the spin-allowed 4 T 1 ( 4 P) → 4 A 2 ( 4 F) and 4 T 1 ( 4 P) → 4 T 2 ( 4 F) transitions.

Periodic Solution of Second-Order Hamiltonian Systems with a Change Sign Potential on Time Scales

Abstract: This paper is concerned with the second-order Hamiltonian system on time scales of the form a.e. , where . By using the minimax methods in critical theory, an existence theorem of periodic solution for the above system is established. As an application, an example is given to illustrate the result. This is probably the first time the existence of periodic solutions for second-order Hamiltonian system on time scales has been studied by critical theory.

Sample study on Heilongjiang coal industry for local government behavior in green supply chain formation

Abstract: The green supply chain of coal industry is a management method in order to promote regional economy, environment, society and sustainable development of enterprise. It makes system environment optimization through the close cooperation between coal enterprises and related industries. Local governments of different levels have different interests in building a green supply chain of coal industry. In the market mechanism, high cost of production will delay and even impede the forming process of green supply chain of coal industry. However, the effective government intervention can make it carry out smoothly. By constructing the behavior model of local government the paper makes sample study on Heilongjiang coal industry in the relationship between local governments' behavior and green supply chain and does research in promoting action on the formation of green supply chain in coal industry.

Establishment of a novel sensitive method for detecting methylation modification on DNA of escherichia coli cell

Abstract: This study focused on finding a novel sensitive method to determine the methylation modification at DNA dam (GATC) sites in Escherichia coli. A new plasmid which contained three GATC sites recognized by restriction enzyme BclI and one GAATTC site recognized by EcoRI was transformed into E. coli stains AB1157(dam +) and GM2929(dam −) respectively. Then the plasmid DNA was digested by restriction enzyme BclI(T*GATCA), which was sensitive to methylation. The results showed that the plasmid derived from AB1157 was not digested while that from GM2929 was, for the methylation level of the former was high while the latter was low. So by detecting the methylation of plasmid transferred into the strain, we could determine whether methylaion existed at DNA dam (GATC) site in E. coli. This method was effective and rapid; moreover, the digested fragments were not dispersive. It also made a basis for the detection of whether methylation occurred in mode beings by low-energy ion beam.

The Optimization of the Conditions in Processing Slime Water of High Concentration and Fine Grain with Bio-flocculant

Abstract: Through the analysis of the biological culturing characteristics of white-rot fungus,the optimum culturing conditions are obtained as follows:Under conditions of 160 r/min of rotational speed,30 ℃ of temperature,90 mL of rice husk Lixivium,35 g/L of glucose mass concentration,3.5 of pH value,the fresh growing trend is best. The slime water granulometric composition is also analyzed,the results of which indicate that those whose granularity is smaller than 0.045 mm account for 55.93% of the total amount,and that those bigger than 0.25 mm occupy 3.75%. With most part of the amount as fine grain,subsidence by gravity seems impossible. This paper further analyzes the effect of single factors such as pH value,amount of biological flocculant to be used,stirring method,and metallic ion on the flocculation of slime water. And through orthogonal experiment,the conditions for the flocculation of slime water by flocculant produced by this fungus are further optimized. The results show that the optimum flocculation activeness is achieved as high as 98.71% under the following conditions:slime water concentration 27.42 g/L; coagulant acid (CaCl2) concentration 5.0 g/L; two stages of stirring (first stage:stirring speed 60 r/min,stirring time 180s; second stage:mixing speed 180 r/min,stirring time 60 s); pH value 11; and flocculant concentration 15 mL/L. Further tests indicate that,the flocculation active materials for the most part exist outside the cells,and they are the extracellular secretion which the mycelium cell produces in the fermentative process.

Influence of Plasma Beam Hardening Operating Current on Microstructure and Performance on Surface of Nodular Cast Iron

Abstract: The influence rule of plasma beam hardening operating current on microstructure and performance on the surface of nodular cast iron was studied The results show that micromelted-solidified hardening and solid transformation hardening on the surface of nodular cast iron can be obtained by adjusting the value of electric current With the increase of the operating current, the width and depth of remelt-solidified layer and hardened layer increase, the hardness firstly goes up and then goes down When taking plasma beam as heat source to quench the surface of nodular cast iron, the graphite of remelt-solidified region is vanished The microstructure of remelt-solidified at room temperature is tiny ledeburite + remaining austenite; and the microstructure of transformation hardening region of is acicular martensite+remaining austenite+spheroid graphite+ferrite; while the microstructure of transition region of is acicular martensite+ledeburite+martensite shell around the graphite nodular Along the depth direction of the hardening layer, the microhardness shows a tendency of firstly going down and then going up, the value slowly drops after achieving t he top, the microhardness of the martensite shell around the graphite nodular is up to 10685 HV01, which is advantageous to enhance wear resistance The highest microhardness appears at the second-surface layer which has a certain distance to the surface Besides there is a softened belt between remelt-solidified and transformation hardening region

Creep and thermal stress analysis of the SMA joint system

Abstract: The coupled thermal-mechanical transient state analysis was used to investigate the SMA joint system under a temperature field.Those fields of temperature,thermal strain,stress and creep were pre-sented for the system.Critical un-bonded parts were obtained in middle interfaces between the joint and pipes.Precautions were proposed in not only creep stresses but also the excessive deformation and creep strain.It supplies a theoretical basis for the structural reliability and design.

Effect of carbon content and microstructure on the yield-strength ratio of steel

Abstract: The experiment on the yield-strength ratio of low-carbon alloy steel was performed and the effect of carbon content and microstructures on the yield-strength ratio of steel was discussed.Theoretical analysis and experimental results indicate that the ferrite grain size can affect the yield-strength ratio of steel,i.e.,the smaller ferrite grain size,the higher the yield-strength ratio.In the meantime,different microstructures can also affect the yield-strength ratio of steel.The yield-strength ratio of steel composed of polygonal ferrite and bainite is lower than that of ferrite and pearlite.Furthermore,grains of M/A island in large quantities distributed in diffusion can increase the tensile strength of steel remarkably and so decrease the yield-strength ratio.