Applied Mechanics and Materials Vols. 325-326

Abstract: The paper describes the construction of an original linear pneumo-hydraulic positioning unit developed by the authors. The mathematical model that describes the functioning of the unit and the simulation results are also presented.

Abstract: t is an in-depth research on the span measurement range ratio that standard throttling gear measures the flow is too small, and proposes the design method of multi-efflux coefficient standard throttling gear. Expanding the lower limit of measurable flow according to the relevant national standards GB/T2624-2006. Solution divides the span measurement range into several segments, each piece span measurement range corresponds to a differential pressure gauge, and calculates corresponding efflux coefficient depending on the GB/T2624-2006 to get many outflow coefficients on the different span measurement sub-range section. Intelligent system chooses corresponding efflux coefficients based on different differential pressure, and ensures measurement accuracy at the same time of expanding the lower limit.

Abstract: The paper presents a method for computing the oxygen transfer speed in water in non-stationary conditions. The theoretical results are verified by experimental researches performed on a new type of fine bubbles generator; the variation of O₂ concentration in water is measured electrically, using an oxygen meter.

Abstract: This paper proposes how to use a domestic data acquisition card to develop a car knock sensor testing and analysis system, which is based on the U.S. NI LabVIEW. The content of the testing section is to design a driver based on the dynamic link library, aimed at making a communication between LabVIEW and the data acquisition card. This system can realize real-time acquisition for the knock sensor output signal, and the testing interface is simple and practical.

Abstract: An approach providing a digital output linearly proportional to capacitance difference for capacitive pressure sensor is presented. Based on sigma-delta (ΣΔ) technique, the structure is insensitive to circuit imperfections and component mismatch, permitting the realization of digitized capacitive sensor readout with good accuracy. Analysis shows that a resolution as high as 20 bits is achievable. Simulation results are given to confirm the effectiveness.

Abstract: The design and mechanical analysis of fracturing string was one of the key technical problems in fracturing operation. Considering contact friction and curvature effect, contact nonlinear problem of fracturing string was solved by space beam element and multidirectional contact gap element method. Contact state, contact reaction force and corresponding frictional resistance between the fracturing string and borehole or inside casing wall could be accurately described by gap element, which generated less simplification in the mechanical model and more precise calculation of force and deformation. The calculations of field examples has shown that while the distance is 10 m, 20 m or 30 m between two packers of fracturing string, maximum axial sliding displacement of the first packer is 0.19 mm and sliding displacement of the second packer is 11.17mm, 23.78mm , or 36.46 mm. The theory basis is provided for the decision of reasonable distance between two packers.

Abstract: The splicing measuring method applied in large-aperture aspheric surface optical elements, can extend the range of precision measuring instrument and expand measurement capability of the system. In this paper, two methods are proposed: the fitting evaluation method and the curvature comparison method in the light of how to reject the redundant data of the splicing coincidence part, and the theoretical analysis are investigated to calculate the theoretical error. The Talysurf PGI 1240 profilometer of Taylor Hobson Company is used as application object to do experimental research. The results show that the curvature comparison method is feasible and has characteristic such as fast speed, high precision, and good operability.

Abstract: In this paper, the thermal ignition delay period of the gasoline-air mixture under the condition of high temperature heat source and temperature-rising heat source in cave depots has been studied using experiment methods. The rules, scopes, and mechanism of thermal ignition delay period are got. It is found that: there is different delay period scope in different ignition model. The delay period for thermal explosion is the shortest, for thermal deflagration, the delay period is longer than that for explosion, usually seconds to a few hundred of seconds.The mechanism of delay period is unification of chemical kinetics and thermodynamics before ignition.

Abstract: The input module of the NERVA space launcher guidance system consisting of the inertial and sensor platform is responsible for the basic accuracy if the ascent trajectory and injection efficiency. The sample rate magnitude and data filtering along the real time trajectory are the only tools available for improving the guidance accuracy up to the level of requirements to secure admissible orbital injection error and the subsequent flight corridor during the orbital ascent. Analysis of the NERVA-1 flight telemetry flow from the onboard inertial platform raises the problem of the optimal selection of the onboard sample rate and of the rate of telemetry, which are not identical. The orbit injection errors are chosen from the orbit altitude constraints and subsequent accuracy requirements for the inertial sensors are derived. They show that the accuracy requirements are moderate and may be covered with almost conventional sensors. To improve the flight guidance accuracy the rocket motor chamber pressure and thrust are measured and observation of the preflight zero drift, recording noise and of the high level of embedded noise during both powered and coast atmospheric flight is performed. Simple filtering based on frequency Fourier analysis is delivered with conclusions regarding the intelligent algorithm enhancement that are developed and implemented on the next generation of flight research drone missiles RT-759M NERVA-2, right in preparation. The main rationale of that algorithm stands in the method of discriminating between false and true information on each measuring point immediately after the data are delivered by the sensors. Learning procedure from previous preflight recordings and from gradual accumulation of concurrent data streams subjected to FF spectral analysis are combined to improve data filtering, for immediate release to the next module of the autopilot. The rate of sampling is optimized from the analysis of the previous flight, inertial data records and test stand pressure and thrust records that show the level of noise. The behavior of the electronics under the dynamical loads of the rocket flight, involving overloads of more than 20 g-s and the level of vibration during the real flight and other sources of measuring errors are also focused in the research. During simulated work of the sensor platform the algorithm has been acceptably validated and prepared for real flight test performance. Information important for the NERVA autopilot design activity is structured through the multiple variance approach.

Abstract: This method of sample preparation for iron, copper, manganese and zinc in wine were studied in this paper. At the preparation period adopted a method using nitric acid to extract, which mostly reduced the losing of metals and saved the time. Determinate the iron, copper, manganese and zinc in wine by AFS, and the recovery is in the range of 102.4 %~107.8 %, and the relative standard deviation is in the range of 0.955 %~3.806 %.