Control-oriented Modeling for Air-breathing Hypersonic Vehicle Using Parameterized Configuration Approach

This article presents a parameterized configuration modeling approach to develop a 6 degrees of freedom （DOF） rigid-body model for air-breathing hypersonic vehicle （AHV）. The modeling process involves the parameterized configuration design, inviscous hypersonic aerodynamic force calculation and scramjet engine modeling. The parameters are designed for airframe-propulsion integration configuration, the aerodynamic force calculation is based on engineering experimental methods, and the engine model is acquired from gas dynamics and quasi-one dimensional combustor calculations. Multivariate fitting is used to obtain analytical equations for aerodynamic force and thrust. Furthermore, the fitting accuracy is evaluated by relative error （RE）. Trim results show that the model can be applied to the investigation of control method for AHV during the cruise phase. The modeling process integrates several disciplines such as configuration design, aerodynamic calculation, scramjet modeling and control method. Therefore the modeling method makes it possible to conduct AHV aerodynamics/propulsion/control integration design.

Investigation on the Optimizing Range of CombustionChamber Configuration Parameters of DSCS

Aim To obtain an optimizing range of the main configuration parameters of double swirls combustion system (DSCS) Methods To analyze the influence of DS combustion cham-ber configuration parameters on fuel spray and mixing by means of the fuel jet developmentperiphery charts obtained by the high speed photography with a modeling test device deve-loped by authors,and to examine it by the tests on a single cylinder diesel engine.Resultsand Conclusion The mixing process can be divided into four phases.The optimizing range of the ration of the inner chamber diameter to the cylinder bore,d2/D,is 0.4-0.7; and the outerchamber diameter,d1 the height of the circular ridge to the piston top face,h1,the radius of outer/inner chamber circle,R1,R2 ,the max depth of outer/inner chamber bowl,H1,H2,etc. are also important

New Spam Filtering Method with Hadoop Tuning-Based MapReduce Naïve Bayes

As the importance of email increases,the amount of malicious email is also increasing,so the need for malicious email filtering is growing.Since it is more economical to combine commodity hardware consisting of a medium server or PC with a virtual environment to use as a single server resource and filter malicious email using machine learning techniques,we used a Hadoop MapReduce framework and Naïve Bayes among machine learning methods for malicious email filtering.Naïve Bayes was selected because it is one of the top machine learning methods(Support Vector Machine(SVM),Naïve Bayes,K-Nearest Neighbor(KNN),and Decision Tree)in terms of execution time and accuracy.Malicious email was filtered with MapReduce programming using the Naïve Bayes technique,which is a supervised machine learning method,in a Hadoop framework with optimized performance and also with the Python program technique with the Naïve Bayes technique applied in a bare metal server environment with the Hadoop environment not applied.According to the results of a comparison of the accuracy and predictive error rates of the two methods,the Hadoop MapReduce Naïve Bayes method improved the accuracy of spam and ham email identification 1.11 times and the prediction error rate 14.13 times compared to the non-Hadoop Python Naïve Bayes method.

Execution Time Analysis of a Gen-2 Remote Computer

The communication in the physical layer between an interrogator and a tag of a passive Radio Frequency Identification （RFID） system operating between 860-960 MHz is defined by the Gen 2 protocol. The tag can be considered a remote executing unit or a computer that executes instructions from the Gen 2 protocol. The selection of the parameter and command configuration within the protocol limitations is critical especially if the time available for the memory operations in a passive RFID system is limited. An effort is made to map the operation of the tag not in its states of operation as elaborately explained in the protocol but rather in its elementary format. The research reported in this article identifies all the parameters that affect the dynamic operation of the tag. The operation is further divided into singulation, read and write; identifying the significant parameters in each case. The choices of the different commands that can be adopted to perform identical operations on the tag are analyzed. The elements to consider in selecting the optimum command configuration are described. The impact of the different parameter and command configuration on the singulation, read and write time is calculated and recorded using a tested Gen 2 simulator program.

Effects of Machine Tool Configuration on Its Dynamics Based on Orthogonal Experiment Method

In order to analyze the influence of configuration parameters on dynamic characteristics of machine tools in the working space, the configuration parameters have been suggested based on the orthogonal experiment method. Dynamic analysis of a milling machine, which is newly designed for producing turbine blades, has been conducted by utilizing the modal synthesis method. The finite element model is verified and updated by experimental modal analysis （EMA） of the machine tool. The result gained by modal synthesis method is compared with whole-model finite element method （FEM） result as well. According to the orthogonal experiment method, four configuration parameters of machine tool are considered as four factors for dynamic characteristics. The influence of configuration parameters on the first three natural frequencies is obtained by range analysis. It is pointed out that configuration parameter is the most important factor affecting the fundamental frequency of machine tools, and configuration parameter has less effect on lower-order modes of the system than others. The combination of configuration parameters which makes the fundamental frequency reach the maximum value is provided. Through demonstration, the conclusion can be drawn that the influence of configuration parameters on the natural frequencies of machine tools can be analyzed explicitly by the orthogonal experiment method, which offers a new method for estimating the dynamic characteristics of machine tools.

Analysis and Key Parameter Optimization Design of Leningrader Seal Performance

In order to improve the performance and service life of the Leningrader seal of the Stirling engine piston rod,interference,pre-load and friction coefficient were taken as influencing factors,and the curved surface response method was adopted to reduce the contact stress of sealing surface and von Mises stress of the sealing sleeve as the response index,with the optimization goal of reducing wear and extending life.The above three key parameters are analyzed and optimized,the influence of each parameter on the sealing performance and service life is obtained,and the best combination scheme of the three is determined.The results show that the interaction between pre-tightening force and interference fit has the greatest impact on contact stress.The interaction between interference fit and friction coeffi-cient has the most significant effect on von Mises stress.The optimized parameters can reduce the maximum contact stress and maximum von Mises stress of the sealing sleeve by 26.3%and 20.6%,respectively,under a media pressure of 5-9 MPa.Test bench verification shows that the leakage of the optimized sealing device in 12 h is reduced by 0.44 cc·min^(-1)(1 cc=1 cm^(3)).The wear rate of the sealing sleeve is 1.08%before optimization and 0.45%after optimization,indicating that the optimized parameters in this paper are effective.

Experimental study on the key factors of low-loss threshing of high-moisture maize

The rates of maize breakage and entrainment loss are high in the harvest of high-moisture maize,which remains an issue with the development of agricultural mechanization.In order to reduce the maize breakage and entrainment loss rates,the correlations among key factors,such as the threshing cylinder speed,concave clearance and feeding rate,and the rates of breakage and entrainment loss during high-moisture maize harvesting were studied in this paper.A single-factor experiment was carried out using a single-longitudinal-axial flow maize harvester,and an orthogonal experiment was carried out using single-and double-longitudinal-axial flow maize harvesters with the Taguchi experimental design method.The single-factor experiment revealed that when the cylinder speed increased,the breakage rate of maize decreased first and then increased,while the entrainment loss rate decreased.The breakage rate of maize decreased as the concave clearance increased,while the entrainment loss rate decreased first and then increased.The optimum value of the concave clearance was positively correlated with the ear diameter of maize;Additionally,the minimum breakage rate of maize occurred when the feeding rate was at the rated value,and the entrainment loss rate increased as the feeding rate increased.The orthogonal experiments revealed that the importance of cylinder speed,feeding rate,concave clearance on the maize breakage and entrainment loss rates were in descending order.The optimum values of parameters for the single-longitudinal-axial flow maize harvester were 370 r/min cylinder speed,40 mm concave clearance and 10 kg/s feeding rate.The optimum values of parameters the double-longitudinal-axial flow maize harvester were 550 r/min cylinder speed,35 mm concave clearance and 10 kg/s feeding rate.The research can provide a reference for parameter configuration and control strategy for the longitudinal-axial flow maize harvester with high-moisture maize.