Cold-spray Ionization Mass Spectrometry for Characterization of Biomolecules in Solution

A direct solution analysis method, coldspray ionization (CSI) mass spectrometry (MS)[1], a variant of electrospray (ESI) MS operating at low temperature (ca. - 80 ～ 10℃), allows facile and precise characterization of labile organic species, especially those in which non-covalent bonding interactions are prominent. We have applies this method to investigations of the solution structures of many labile organic species, including unstable reagents and reaction intermediates, asymmetric catalysts, supramolecules, and even primary biomolecules.     

寡糖混合物快原子轰击质谱分析研究

In positive-ion fast atom bombardment (FAB) mass spectrometry, it is difficult to determine the molecular weights of oligosaccharides due to the low abundance of [M H]^ ion. However, when oligosaccharides are mixed with an appropriate amount of NaCI and LiCI, two highly abundant peaks[M Na]^ and [M Li]^ appear in FABmass spectra and their mass difference is 16. From the adduct ions, the molecular weights of oligosaccharides can be determined unambiguously.In the same way, when a mixture of oligosaccharides was mixed with an appropriate amount of Na^ and Li^ , pairs of strong peaks appeared in the FAB mass spectra. These adduct ions were easily recognized due to the fact that they were very strong and their mass difference was union(16u). From these adduct ions, the molecular weight of each oligosaccharides in mixture may be determined.     

Performance study based on inner flow field numerical simulation of magnetic drive pumps with different rotate speeds

Magnetic drive pump has gotten great achievement and has been widely used in some special fields.Currently,the researches on magnetic drive pump have focused on hydraulic design,bearing,axial force in China,and a new magnetic drive pump with low flow and high head have been developed overseas.However,low efficiency and large size are the common disadvantages for the magnetic drive pump.In order to study the performance of high-speed magnetic drive pump,FLUENT was used to simulate the inner flow field of magnetic drive pumps with different rotate speeds,and get velocity and pressure distributions of inner flow field.According to analysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation.Based on the analysis of velocity and pressure,this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating the power loss in impeller and volute,hydraulic loss,volumetric loss,mechanical loss and discussing the different reasons of power loss between the magnetic drive pumps with different rotated speeds.In addition,the magnetic drive pumps were tested in a closed testing system.Pressure sensors were set in inlet and outlet of magnetic drive pumps to get the pressure and the head,while the pump efficiency could be got by calculating the power loss between the input power and the outlet power.The results of simulation and test were similar,which shows that the method of simulation is feasible.The proposed research provides the instruction to design high-speed magnetic drive pump.     

Recursive least square vehicle mass estimation based on acceleration partition

Vehicle mass is an important parameter in vehicle dynamics control systems. Although many algorithms have been developed for the estimation of mass, none of them have yet taken into account the different types of resistance that occur under different conditions. This paper proposes a vehicle mass estimator. The estimator incorporates road gradient information in the longitudinal accelerometer signal, and it removes the road grade from the longitudinal dynamics of the vehicle. Then, two different recursive least square method （RLSM） schemes are proposed to estimate the driving resistance and the mass independently based on the acceleration partition under different conditions. A 6 DOF dynamic model of four In-wheel Motor Vehicle is built to assist in the design of the algorithm and in the setting of the parameters. The acceleration limits are determined to not only reduce the estimated error but also ensure enough data for the resistance estimation and mass estimation in some critical situations. The modification of the algorithm is also discussed to improve the result of the mass estimation. Experiment data on asphalt road, plastic runway, and gravel road and on sloping roads are used to validate the estimation algorithm. The adaptability of the algorithm is improved by using data collected under several critical operating conditions. The experimental results show the error of the estimation process to be within 2.6%, which indicates that the algorithm can estimate mass with great accuracy regardless of the road surface and gradient changes and that it may be valuable in engineering applications. This paper proposes a recursive least square vehicle mass estimation method based on acceleration partition.     

甘氨双唑钠及其一个微量成分的质谱研究

The synthesis of sodium glycidazole yields three products detected by HPLC. Electrospray ionization mass spectrometry has been successfully applied to identify the three products. ESI mass spectrometry demonstrated that the first component is 2-nitro-5-emthylimidazole as impurity and the third component is the target compound, sodium glycidazole, as main product. The second and the third components were further investigated by the scanning of the daughter ion at m/z 373[M H]^ , m/z 520[M H]^ using ESI tandem mass spectrometry. The experimental results show that the second component has the structure similar to the desired product but without one imidazolering.     

MALDI-TOF-MS分析基因重组糖蛋白rhEPO的一级结构

Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) is a rather new ‘soft ionization’ techniques. Because of its high sensitivity and accuracy, it has been widely used in detection and characterization of macromolecules such as peptides, proteins and olignucleotides. It also has been applied successfully in the analysis of posttranslational modification of proteins, such as phosphorylation and glycosylation. Compared with the conventional chemical methods, mass spectrometry is simple, rapid and does not require radiolabeling. In this research, a systematic method to analyse glycoprotein by MALDI-TOF-MS was developed. A practical sample--recombinant human erythropoietin was analysed by the method. The molecular weight, content of carbohydrate and glycosylation sites of the glycoprotein were determined by MALDI-TOF-MS, combined with the endo-glycosidase digestion and peptide mapping. The experimental result shows that MALDI-TOF-MS is a very powerful technique in the characterization of glycosylation proteins.     

Numerical investigation of the aerodynamic performance affected by spiral inlet and outlet in a positive displacement blower

The flow in the positive displacement blower is very complex.The existing two-dimensional numerical simulation cannot provide the detailed flow information,especially flow characteristics along the axial direction,which is unfavorable to improve the performance of positive displacement blower.To investigate the effects of spiral inlet and outlet on the aerodynamic performance of positive displacement blower,three-dimensional unsteady flow characteristics in a three-lobe positive displacement blower with and without the spiral inlet and outlet are simulated by solving Navier-Stokes equations coupled with RNG k-ε turbulent model.In the numerical simulation,the dynamic mesh technique and overset mesh updating method are used.The computational results are compared with the experimental measurements on the variation of flow rate with the outlet pressure to verify the validity of the numerical method presented.The results show that the mass flow rate with the change of pressure is slightly affected by the application of spiral inlet and outlet,but the internal flow state is largely affected.In the exhaust region,the fluctuations of pressure,velocity and temperature as well as the average values of velocity are significantly reduced.This illustrates that the spiral outlet can effectively suppress the fluctuations of pressure,thus reducing reflux shock and energy dissipation.In the intake area,the average value of pressure,velocity and temperature are slightly declined,but the fluctuations of them are significantly reduced,indicating that the spiral inlet plays the role in making the flow more stable.The numerical results obtained reveal the three-dimensional flow characteristics of the positive displacement blower with spiral inlet and outlet,and provide useful reference to improve performance and empirical correction in the noise-reduction design of the positive displacement blowers.     

Enhancement of Voice Quality and Bit-rate Reduction by Prosodic Control in G.723.1 Vocoder

Speech coding techniques have been studied not only to reduce the complexity and bit rate but also to improve the sound quality.CELP type vocoder,used as standard,supports the great sound quality even low bit rate.In this paper,the preprocessing of input speech to reduce the bit rate is different from the conventional vocoder.Different kinds of parameter are used for the preprocessing compared with the other parameters to find the more appropriate parameter for the vocoder.The parameters are used to synthesize the speech not to encode or decode for coding technique so we proposed the simple algorithm not to have the influence on the processing time or the computation time.The parameters in the preprocessing step are speaking rate,duration,and PSOLA technique.     

Fuzzy chaos control for vehicle lateral dynamics based on active suspension system

The existing research of the active suspension system（ASS） mainly focuses on the different evaluation indexes and control strategies. Among the different components, the nonlinear characteristics of practical systems and control are usually not considered for vehicle lateral dynamics. But the vehicle model has some shortages on tyre model with side-slip angle, road adhesion coefficient, vertical load and velocity. In this paper, the nonlinear dynamic model of lateral system is considered and also the adaptive neural network of tire is introduced. By nonlinear analysis methods, such as the bifurcation diagram and Lyapunov exponent, it has shown that the lateral dynamics exhibits complicated motions with the forward speed. Then, a fuzzy control method is applied to the lateral system aiming to convert chaos into periodic motion using the linear-state feedback of an available lateral force with changing tire load. Finally, the rapid control prototyping is built to conduct the real vehicle test. By comparison of time response diagram, phase portraits and Lyapunov exponents at different work conditions, the results on step input and S-shaped road indicate that the slip angle and yaw velocity of lateral dynamics enter into stable domain and the results of test are consistent to the simulation and verified the correctness of simulation. And the Lyapunov exponents of the closed-loop system are becoming from positive to negative. This research proposes a fuzzy control method which has sufficient suppress chaotic motions as an effective active suspension system.     

DEVELOPMENT OF A 3-DOF MICRO-POSITIONING WORKPIECE TABLE

In order to achieve active grinding control, a novel numerical control micropositioning workpiece table with a resolution of 6 nm has been developed. The table is driven by three piezoelectric actuators mounted on the base. An elastic structure with three half-notch flexure hinges is designed to apply preload to the piezoelectric actuators. The position of flexure hinges is also elaborately designed with consideration to reduce the bending deformation of the moving part. Three capacitive sensors are used to form close loop control system. Considering the table as a damped 3-DOF mass-spring system, the models of static and dynamic stiffness and error owing to the action of external forces have been established. In order to make the table have high resolution and positioning accuracy, an error compensation algorithm is implemented by using the established models. The experimental testing has been carried out to verify the performance of the workpiece table and the established models of the micropositionin     

NUMERICAL MODELING OF MULTI- CYLINDER ELECTRO-HYDRAULIC SYSTEM AND CONTROLLER DESIGN FOR SHOCK TEST MACHINE

A high fidelity dynamic model of a high-energy hydraulically-actuated shock test machine for heavy weight devices is presented to satisfy the newly-built shock resistance standard and simulate the actual underwater explosion environments in laboratory as well as increase the testing capability of shock test machine. In order to produce the required negative shock pulse in the given time dura-tion,four hydraulic actuators are utilized. The model is then used to formulate an advanced feedfor-ward controller for the system to produce the required negative waveform and to address the motion synchronization of the four cylinders. The model provides a safe and easily controllable way to per-form a “virtual testing” before starting potentially destructive tests on specimen and to predict per-formance of the system. Simulation results have demonstrated the effectiveness of the controller.     

Synergistically Toughening Effect of SiC Whiskers and Nanoparticles in Al_2O_3-based Composite Ceramic Cutting Tool Material

In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al_2O_3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al_2O_3-SiC_w-SiC_(np) advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al_2O_3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al_2O_3-SiC_w-SiC_(np) composite with both 20 vol% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al_2O_3-SiC_w-SiC_(np) is 730±95 MPa and fracture toughness is 5.6±0.6 MPa·m~(1/2). The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.     

Mesoplasticity approach to studies of the cutting mechanism in ultra-precision machining

There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plasticity and continuum mechanics. Very few attempts, however, have been reported in ultra-precision machining studies. A mesoplasticity approach advocated by Lee and Yang is adopted by the authors and is successfully applied to studies of the micro-cutting mechanisms in ultra-precision machining. Traditionally, the shear angle in metal cutting, as well as the cutting force variation, can only be determined from cutting tests. In the pioneering work of the authors, the use of mesoplasticity theory enables prediction of the fluctuation of the shear angle and micro-cutting force, shear band formation, chip morphology in diamond turning and size effect in nano-indentation. These findings are verified by experiments. The mesoplasticity formulation opens up a new direction of studies to enable how the plastic behaviour of materials and their constitutive representations in deformation processing, such as machining can be predicted, assessed and deduced from the basic properties of the materials measurable at the microscale.     

Mapping of mechanical properties of WC–Co using nanoindentation

High-resolution measurements of mechanical properties are of immense importance in metallurgy. Measuring the intrinsic properties of each phase separately in multiphase materials gives information that is valuable for the development of new materials and for modelling. In this work, nanoindentation has been used to reveal mechanical properties of different phases in WC–Co with very high resolution. The resolution limits of the equipment and this material as well as various techniques to accomplish the measurements were evaluated. By making indents only 0.1 μm apart and using very low loads (1 mN) it was possible to distinguish between the two different phases, WC and Co. Maps created from the measured properties, hardness and Young’s modulus, were in excellent agreement with SEM images of the same area. Furthermore, it was also possible to detect an increased hardness of the Co binder phase by a factor of four as compared to the bulk hardness of Co. This work verifies experimentally what several authors have proposed earlier based on modelling. This revised version was published online in August 2006 with corrections to the Cover Date.     

COMPUTATIONAL FLUID DYNAMICS RESEARCH ON PRESSURE LOSS OF CROSS-FLOW PERFORATED MUFFLER

The pressure loss of cross-flow perforated muffler has been computed with the procedure of physical modeling,simulation and data processing. Three-dimensional computational fluid dynam-ics (CFD) has been used to investigate the relations of porosities,flow velocity and diameter of the holes with the pressure loss. Accordingly,some preliminary results have been obtained that pressure loss increases with porosity descent as nearly a hyperbolic trend,rising flow velocity of the input makes the pressure loss increasing with parabola trend,diameter of holes affects little about pressure loss of the muffler. Otherwise,the holes on the perforated pipes make the air flow gently and meanly,which decreases the air impact to the wall and pipes in the muffler. A practical perforated muffler is used to illustrate the available of this method for pressure loss computation,and the comparison shows that the computation results with the method of CFD has reference value for muffler design.     

Analysis of Unbalances Forces Using Methods of Identification and Finite Elements

The study of damage in rotating machineries is of fundamental interest in the fields of machine and structure design. A rotating system, supported by bearings and under some dynamic conditions, can generate a variety of problems that are encountered in many different types of rotating machines. One of these problems is the unbalance due to non-homogeneous mass distribution along the shaft. One of the techniques which are widespread today is the identification of parameters and excitation forces that may well followed by monitoring the evolution and change of possible variations of these parameters. Although several methods for the identification of unbalance excitation force are available in the literature, none of them can be considered unrestricted to be applied for all rotating systems. In this study, two methodologies to identify unknown excitations, such as unbalance, have been proposed. This project refers to the analysis of unbalanced forces from displacement parameters and speed by using methods of identification by Fourier series and Legendre polynomials together with the finite element method, state observers in reasons of the problem of absence of signs of rotational displacement, bandpass filter were used to noise suppression of the data collected from the experimental part, Quasi-Newton method to minimize a function in which the bearing stiffness and its damping are unknowns, and also the experimental verification of the methodology, using for this system owned by a rotary mechanical vibrations of the Department of Mechanical Engineering of Faculty of Engineering, campus of llha Solteira.     

Innovative Proof for Elastic Flexure Formulas

The basic problem in teaching mechanics of materials is that some subjects discussed in the reference books are not easy to understand for most of the students. Using experience of many years teaching mechanics of materials, we have been continuously trying to find easier methods to help the students get a better understanding of fundamental concepts. This effort and investigation has led to innovative and simple approaches to prove the equations much easier than the existing ones and also to clarify complicated concept. In this paper, we are offering our innovative proof for elastic flexure formulas as well as an interesting model for the moment sign convention in the cross section of a beam. In this method, considering a portion of a beam under pure bending and obtaining the stress distribution in the cross section and applying the balance of the considered portion, we prove the Elastic Flexure Formulas much easier than the existing methods. Emphasizing on deeper understanding, some notes and a new model are offered during this proof.     

不同编织方式下陶瓷基复合材料表面流动特性数值计算研究（英文）

Ceramic matrix composites(CMCs) are one of the most promising materials in the field of gas turbines,with superior weight and thermal properties. Its surface morphology is different from the traditional casting airfoil components, which mainly comes from different weaving methods and different braided tow thickness. However, few people have studied the influence of surface morphology of ceramic matrix composites(CMCs) on the development of boundary layer and the resulting flow loss. In this pape...     

Single-phase computational fluid dynamics applicability for the study of three-dimensional flow in 5′ 5 rod bundles with spacer grids

Spacer grids play an important role in pressurized water reactor(PWR) fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studies are performed without regarding dimple and spring of spacer grids,just considering mixing vane.Moreover,these studies use k-ε turbulence model without considering the suitability of the other turbulence models upon the different spacer grids flow.A study is carried out to understand the 3-D single-phase flow in AFA-2G 5×5 rod bundles with spacer grids based on numerical method.In order to investigate the suitability of different turbulence models,k-ε model and k-ω model,the influence of different parts of spacer grid on the fluid flow is also predicted.By using second-order upwind scheme,hybrid grids technique,and improved SIMPLEC algorithm,the Reynolds averaged mass conservation and momentum conservation equations are solved,and the pressure and velocity field of flow are obtained.The numerical simulation results are compared with experiment results and the agreement is satisfactory.The simulation results show the influences of the spring,dimple and mixing vane,and the different characteristics of the k-ε model and k-ω model.Comparing with the experiment results,the simulation results suggest that the k-ω model is suitable for the simulation of the rod bundle flow with spacer grids;the spring and dimple are the main causes of the pressure loss in the spacer grid channel.The friction coefficient of the channel with spring and dimple is 1.5 times the coefficient of the channel with the vane.These results are beneficial to enhance the simulation ability of spacer grids flow and optimization design ability of spaces grid.     

Fluorescence Spectra and Luminescent Mechanism of Vitamin b Fmily Based on Solid Powder Direct Illumination

The simple approach to acquire the fluorescence spectra of vitamin b1,b2 and b6 is proposed by direct illumination on solid powder sample.The experimentally acquired fluorescence spectra are in accordance with the previous measurements on soluble samples.The fluorescence spectra for a mixture of vitamins b1,b2 and b6 with different concentrations have been investigated,and the fluorescence mechanism is explained on the basis of molecular structure.Possible reasons of the blue-shift of the fluorescence peak and enhancement of the peak power are explained as well.The advantages of solid powder method is analyzed and discussed.