从燃料经济性看原动力机的发展

本文从原动力机的发展演变过程，通过对六种主要机型动力性和经济性的分析比较，认为动力机工作形式的发展变化，一方面是由于动力机的功率、效率等动力性的要求，另一方面与燃料的经济性和可持续发展有着密不可分的关系。

我国市场经济的动力结构及宏观调控

本文从人们从事劳动活动的一般追求出发，论述了经济人的追求结构和各种动力源的特性。根据对各种动力结构的实证分析，总结出其共同特点和一般变动规律，并在此基础上依据我国的客观实际情况，提出了我国市场经济发展的动力结构和这种动力结构对政府宏观调控的要求。

论安全管理的五个层次和三个驱动力

从多年的工作实践分析认为,企业安全管理模式可以归纳为五个层次和三个原驱动力。这五个方面的因素互相渗透、互相促进、互相制约,形成事故预防的有机整体。在一定的条件和范围内,当一个因素一定时,另一个因素控制得越好,事故发生的概率就越低。人因事故的防范采取以往基于多米诺骨牌原理的策略已无能为力,必须采取技术手段、组织手段、文化手段融为一体的纵深防御策略,任何单一的或孤立的措施都将是低效的。

我国企业技术创新调查分析

以我国某工业基地70多家企业技术创新状况调查为分析背景,从企业技术创新投入与产出、企业技术创新的动力源及技术源、企业技术创新战略与创新目标、企业技术创新成功与障碍因素等多个方面探讨了我国企业技术创新的现实状况。

双层冰中量子相变研究

针对实验所得的双层冰体系,采用原胞动力学平均场理论,结合连续时间量子蒙特卡罗方法,设计开发了一套模拟双层冰结构的准三维六角晶格系统,研究了强关联相互作用与温度的竞合对系统中金属-莫特绝缘相变的影响,结果表明,通过对体系的态密度、双占据数和费米面的计算,可以看出随着相互作用的增加,氧原子经过的金属-莫特绝缘相变(如T/t=0.2时U_(C)/t=6.5)为二级相变。由于体系受温度影响形成近藤共振峰,氢原子的费米面始终存在尖锐的费米液状峰。以双层冰实验为依据,仿真其发生量子相变的过程,计算结果将为双层冰在强关联方面的研究提供理论参考。

Solid-state reduction kinetics and mechanism of pre-oxidized vanadium-titanium magnetite concentrate

The solid-state reduction kinetics of pre-oxidized vanadium-titanium magnetite concentrate was studied. The phase and microstructure of the reduction product were characterized by XRD, SEM and EDS methods, based on which the mechanism of the solid-state reduction was investigated. The results showed that using coal as reductant at 950-1100 °C, the solid-state reduction of the pre-oxidized vanadium-titanium magnetite concentrate was controlled by interface chemical reaction and the apparent activation energy was 67.719 k J/mol. The mineral phase transformation during the reduction process can be described as follows： pre-oxidized vanadium-titanium magnetite concentrate → ulvospinel → ilmenite → Fe Ti2O5 →（FenTi1-n）Ti2O5. M3O5-type（M can be Fe, Ti, Mg, Mn, etc） solid solutions would be formed during the reduction process of the pre-oxidized vanadium-titanium magnetite concentrate at 1050 °C for 60 min. The poor reducibility of iron in M3O5 solid solutions is the main reason to limit the reduction property of pre-oxidized vanadium-titanium magnetite concentrate.

Kinetics of extracting magnesium from mixture of calcined magnesite and calcined dolomite by vacuum aluminothermic reduction

The vacuum aluminothermic reduction of the mixture of calcined magnesite and calcined dolomite was studied. An isothermal reduction method satisfying the vacuum aluminothermic reduction was proposed. The experiments were carried out at 4 Pa. The results indicate that the reduction rate is increased with increasing temperature, content of aluminum and pellet forming pressure. The XRD patterns of pellets at different reduction stages confirm that the reduction process can be roughly classified into three stages：the formation of MgAl2O4, and Ca12Al14O33 phases;the phase transformation from MgAl2O4 and C12A7 to CaAl2O4;the formation of CaAl4O7 phase. The experimental data were divided into three parts according to the kinetic models. The apparent activation energies of the three parts were determined to be 98.2, 133.0 and 223.3 kJ/mol, respectively.

Non-isothermal reduction kinetics of Fe_2O_3-NiO composites for formation of Fe-Ni alloy using carbon monoxide

The non-isothermal reduction kinetics and mechanism of Fe2O3-NiO composites with different Fe2O3-NiO compacts using carbon monoxide as reductant were investigated. The results show that the reduction degree increases rapidly with increasing the content of NiO, and the presence of NiO also improves the reduction rate of iron oxides. It is found that NiO is preferentially reduced at the beginning of the reactions, and then the metallic Ni acts as a catalyst promoting the reduction rate of iron oxides. It is also observed that the increase of the Ni O content enhances the formation of awaruite(FeNi3) but decreases the percentage of kamacite(Fe,Ni) and taenite(Fe,Ni). The particle size of the materials tends to be uniform during the reduction process due to the presence of metallic nickel, metallic iron and the formation of Fe-Ni alloy. The concentration of CO in the product gas is greater than that of CO2 at the beginning of the reaction and then slows down. The fastest reduction rate of Fe2O3-NiO composites with CO appears at 400-500 °C, and nucleation growth model can be used to elucidate the reduction mechanism. Nucleation growth process is found to be the rate controlling step when the temperature is lower than 1000 °C.

AIRCRAFT FLIGHT SAFETY ANALYSIS IN LOW ALTITUDE AIRSPACE

The low altitude airspace will be open in China, general aviation flights are tremendously increased. Whether aircrafts can fly safely and how to determine the requirements of safety flight are the problems needed to be confirmed. Under this circumstances, based on the international Civil Aviation Organization（ICAO） criteria and the standards made by CAAC, this paper adopts the ＂See and Avoid＂ principle. Under the binding conditions of flight rules, visibility requirements, responding time, the aircraft speed, circle banking angle or the climbing angle, based on its study on aircraft dynamics principles, this paper establishes a mathematical collision avoidance model for head-to-head traffic and crossing converging traffic at the same level. And the safety separation requirements of the aircrafts in low altitude flight are equantitatively analyzed. Finally, the Matlab software is used to analyze the above method. The result shows that the safe traffic avoidance of the converging traffic at the same level meets certain flight conditions, while intersecting the traffic at the same level can safely avoid the collision.

Simulation study on non-linear effects of initial melt temperatures on microstructures during solidification process of liquid Mg_7Zn_3 alloy

The non-linear effects of different initial melt temperatures on the microstructure evolution during the solidification process of liquid Mg7Zn3 alloys were investigated by molecular dynamics simulation, The microstructure transformation mechanisms were analyzed by several methods. The system was found to be solidified into amorphous structures from different initial melt temperatures at the same cooling rate of 1×10^12 K/s, and the 1551 bond-type and the icosahedron basic cluster （12 0 12 0 ） played a key role in the microstructure transition. Different initial melt temperatures had significant effects on the final microstructures. These effects only can be clearly observed below the glass transition temperature Tg; and these effects are non-linearly related to the initial melt temperatures, and fluctuated in a certain range. However, the changes of the average atomic energy of the systems are still linearly related with the initial melt temperatures, namely, the higher the initial melt temperature is, the more stable the amorphous structure is and the stronger the glass forming ability will be.

Application of the generalized quasi-complementary energy principle to the fluid-solid coupling problem

The fluid-solid coupling theory, an interdisciplinary science between hydrodynamics and solid mechanics, is an important tool for response analysis and direct design of structures in naval architecture and ocean engineering. By applying the corresponding relations between generalized forces and generalized displacements, convolutions were performed between the basic equations of elasto-dynamics in the primary space and corresponding virtual quantities. The results were integrated and then added algebraically. In light of the fact that body forces and surface forces are both follower forces, the generalized quasi-complementary energy principle with two kinds of variables for an initial value problem is established in non-conservative systems. Using the generalized quasi-complementary energy principle to deal with the fluid-solid coupling problem and to analyze the dynamic response of structures, a method for using two kinds of variables simultaneously for calculation of force and displacement was derived.

The bond graph model of planar flexible multibody mechanical systems and its dynamic principle

In order to increase the efficiency and reliability of the dynamic analysis for flexible planar linkage containing the coupling of multi-energy domains, a method based on bond graph is introduced. From the viewpoint of power conservation, the peculiar property of bond graph multiport element MTF is discussed. The procedure of modeling planar flexible muhibody mechanical systems by bond graphs and its dynamic principle are deseribed. To overcome the algebraic difficulty brought by differential causality anti nonlinear junction structure, the constraint forces at joints can be considered as unknown effort sources and added to the corresponding O-junctions of system bond graph model. As a result, the automatic modeling on a computer is realized. The validity of the procedure is illustrated by a practical example.

Unexplained liver laceration after metastasis radiofrequency ablation

Many studies have established the role of radiofrequency (RF) ablation as a minimally invasive treatment for liver metastases. Although relatively safe, several complications have been reported with the increased use of RF ablation. We describe here a case of unexplained liver laceration after a RF procedure. A woman who presented a solitary metachronous liver metastasis underwent RF ablation treatment for this lesion. Six hours later the patient displayed fatigue and pallor. Emergency blood tests showed a haemoglobin level of < 7 g/dL and markedly elevated transaminase levels. A computed tomography examination revealed two areas of liver laceration with haematoma, one of them following the path of the needle and the other leading away from the f irst. Following a blood transfusion, the patient was haemodynamically stable and completely recovered 24 h later. The patient remained in bed for 1 wk. No surgical intervention was required, and she was discharged 1 wk later.

Kinetic Study of Atom Transfer Radical Polymerization of 2-(N,N-Dimethylamino)ethyl Methacrylate

A kinetic model was developed to describe the atom transfer radical polymerization (ATRP) of 2(N,N-dimethylarnino) ethyl methacrylate (DMAEMA). The model was based on a polymerization mechanism, which included the atom transfer equilibrium for primary radical, the propagation of growing polymer radical, and the atom transfer equilibrium for the growing polymer radical. An experiment was carried out to measure the conversion of monomer, the number-average molecular weight of polymer and molecular weight distribution for the ATRP process of DMAEMA. The experimental data were used to correlate the kinetic model and rate constants were obtained. The rate constants of activation and deactivation in the atom transfer equilibrium for primary radical are 1.0 x 10(4) L(.)mol(-1.)s(-1) and 0.04 L(.)mol(-1.)s(-1), respectively. The rate constant of the propagation of growing polymer radical is 8.50 L(.)mol(-1.)s(-1), and the rate constants of activation and deactivation in the atom transfer equilibrium for growing polymer radical are 0.045 L(.)mol(-1.)s(-1) and 1.2 x 10(5) L(.)mol(-1.)s(-1), respectively. The values of the rate constants represent the features of the ATRP process. The kinetic model was used to calculate the ATRP process of DMAEMA. The results show that the calculations agree well with the measurements.

Study on Kinetics of Iron Oxide Reduction by Hydrogen

Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed. Influence of external diffusion, internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been determined. In the experiments, in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe203 to Fe3O4, the reaction temperatures were set between 440 ℃ and 490 ℃. However, in order to distinguish the reduction of Fe304 to FeO from that of FeO to Fe, the reaction temperature in the experiment was set to be greater than 570 ℃. Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data.

Effect of sodium carbonate addition on carbothermic reduction of ilmenite concentrate

The enhanced reduction mechanism and kinetics of different Na_(2)CO_(3) additions in the carbothermic reduction of ilmenite concentrate were investigated.The reduction process was carried out at different heating rates in a thermogravimetry facility,and the kinetics was studied using the Starink method.The results indicate that Na_(2)CO_(3) addition enhanced the reduction effect as well as reduced the initial temperature of the reaction and the activation energy by increasing reactant activity in reactant form;however,it deteriorated the late-stage kinetic conditions by generating a molten phase,thereby reducing the reaction rate in the late stages of reduction.The average apparent activation energies of ilmenite concentrate with 0%,3%,and 6%Na_(2)CO_(3) are 447,289,and 430 kJ/mol,respectively.The results from kinetics parameters confirm that Na_(2)CO_(3) addition accelerated the reduction kinetics;however,excessive addition worsened the reduction kinetics.

Molecular dynamics study of viscosity of aqueous NaCl solution confined in nanoscale channels

A physical model of bulk-nanochannel-bulk with buffer baths is built up using nonequilibrium molecular dynamics （MD） simulation to study the effects of vibrating silicon atoms on the viscosity of aqueous NaCl solutions confined in the nanochannel. The simulation is performed under different moving speeds of the upper wall, different heights and different surface charge densities in the nanochannel. The simulation results indicate that with the increase in the surface charge density and the decrease in the nanochannel height and the shear rate, the vibration effect of silicon atoms on the shear viscosity of the confined fluid in the nanochannel cannot be ignored. Compared with still silicon atoms, the vibrating silicon atoms result in the decrease in the viscosity when the height of the nanochannel is less than 0.8 nm and the shear rate is less than 1.0 ×10^11 s^-1, and the effect of the vibrating silicon atoms on the shear viscosity is significant when the shear rate is small. This is due to the fact that the vibrating silicon atoms weaken the interactions between the counter-ions （Na^＋ ） and the charged surface.

Adsorption of ruthenium ions on activated charcoal: influence of temperature on the kinetics of the adsorption process

Influence of temperature on ruthenium adsorption on activated charcoal from 3 mol/L HNO3 solutions was inves- tigated in the temperature range of 288 K to 308 K. It was observed that the rise in temperature increases the adsorption of ru- thenium ions on activated charcoal and follows the kinetics of first order rate law with rate constant values 0.0564?0.0640 min?1 in the temperature range of 288 K to 308 K respectively. The activation energy for the adsorption process was found to be 1.3806 kJ/mol. Various thermodynamics quantities namely ?H, ?S and ?G were computed from the equilibrium constant KC values. The results indicated a positive heat of adsorption, a positive ?S and a negative ?G.

Reactive spontaneous infiltration of Al-activated TiO_2 by molten aluminum

The reactive spontaneous infiltration of Al-activated TiO2 (anatase) was investigated. Pure Al powder was blended with TiO2 for activation. They were compacted into the preform and then sealed within 6060 alloy mould. The activation and infiltration were carried out in 6060 alloy bath for 1 h and comparative sintering experiments were carried out in an argon protected environment under the same conditions of temperature and duration. X-ray diffraction analysis proved that the Al sealed environment was superior to the argon protection on activating the reaction between Al and TiO2. The blending ratio of TiO2 to Al and the temperature were found to play the most important role in infiltration by affecting infiltration and reaction kinetics. Three main types of microstructures were observed after infiltration: full infiltration, partial infiltration with the formation of cracks and no infiltration. The formation of these microstructures was explained on the basis of reaction kinetics and local volume changes due to the reactions. Ultimately, it is found that to obtain an overall good spontaneous infiltration, a TiO2 to Al blending ratio around 3:7 in volume and an infiltration temperature around 900 °C are the most suitable.

Theoretical Studies on the Dynamics of the Fluorine Atom Reaction with trans- 1,3-butadiene

Theoretical studies of F atom reaction with trans-1,3-butadiene were carried out at the CCSD（T）/6- 311G（d,p）/B3LYP/6-311G（d,p） levels. Energies and structures for all reactants, products and transition states were determined. Two reaction pathways involving the formation of the complexes CH2CHCHFCH2 and CH2CHCHCH2F were found in this reaction. Theoretical results suggest that the H atom channel observed in previous crossed beam experiment occurs likely via these two long-lived complex formation pathways. For the complex CH2CHCHFCH2 pathway, another reaction channel （C2H3＋C2H3F） is also accessible. Relative importance of the C2H3＋C2H3F channel versus the H formation channel via the same reaction pathway has also been estimated, suggesting that it would be difficult to observe the C2H3＋C2H3F channel in a crossed molecular beam experiment. Theoretical analysis also shows that the HF formation proceeds via direct abstraction mechanisms, though it is likely a minor process in this reaction.