Applied Mechanics and Materials Vols. 271-272

Abstract: The security of software is threatened by piracy, tampering and reverse engineering. Attackers attempt to get important algorithms and sensitive data of software by static analysis or reverse engineering. Software protection becomes an important problem. The algorithm of code obfuscation based on class splitting is proposed that uses of obfuscation technology. The definition of class splitting and realization on algorithm are described. At the same time, the performance on algorithm is analyzed. The obfuscation method enhances the degree of complication about program and static analysis becomes more difficult. The algorithm is applicable to object-oriented program with class structure.

Abstract: It is a special modality of solid-fluid conduit flow for the sand transporting procedure in wellbore. Under the action of heavy oil, because of the difference of the borehole location, the transporting mechanic of sand is not the same. For the vertical wellbore, sand particles are mainly dominated by the drag forces and carried out of the hole; however, for the horizontal wellbore, sand particles are under complex forces and show different flow state. In different flow state, the sand particles are controlled by different forces, the heavy oil’s sand transporting capacity is changed. This paper begins with the analysis of the stress of the sand particles, and deeply analyses the vertical and horizontal wellbore, the stress of sand particles in the heavy oil’s sand mixing flow procedure, and then study the heavy oil’s sand transporting capacity.

Abstract: Studies the influence of air volume, temperature and relative humidity on the SMER of a certain type dehumidifier by orthogonal experiments. The experiment result shows that the relative humidity has more influence on the most SMER than the temperature does.

Abstract: For the rapid response to production scheduling problem driven by high-density production tasks, a dynamic scheduling technology for the large precision strip products assembly with a mixture of task time nodes and line-rail space is proposed. A scheduling constrained model containing coverage, proximity, timeliness and resource is established. A linear rail space production scheduling technology using heuristic automatic scheduling and event-driven method is put forward. The time rule based on delivery and single completion assembly is formed, at the same time the space rule based on the adjacent rail and comprehensive utilization is researched. Supposing the privilege of single product assembling as the core, the scheduling parts filter method based on multiple constraints and former rules. For the space layout problem, a clingy forward and backward algorithms is proposed to judge the assemble position regarding the space comprehensive utilization rate. The classification of the various disturbances in the actual production is summarized. Three basic algorithms are proposed, including insertion, moving and re-scheduling algorithm, in order to solve the assembly dynamic scheduling problem driven by production disturbance events. Finally, take rocket as the example， the rocket assembly space production scheduling system is developed, combining with the proposed algorithm. The practicability of the system is validated using real data.

Abstract: To change the status of time-consuming and over-reliance on technicians in mechanical system alignment process, performance prediction based on dynamic alignment was proposed. The mapping relationship between alignment process parameters and machine dynamic characteristics was established. A large number of computational experiments are implemented by adjusting the value of process parameters in order to learn and anticipate experimental data and also find out the rules of process parameters on machine dynamic characteristics. The method can optimize the alignment process, guide technician alignment, modify the theory mapping, and improve the alignment efficiency.

Abstract: This paper mainly studies the change rules of interior ballistic performance under different loaded conditions, especially the maximum pressure and the muzzle velocity. There are six parameters affect the performance. The results show that, changing one of the all parameters, the maximum pressure and velocity will be increased with the increase of propellant shape coefficient χ; increased with the charge increases; increased as the propellant force increases; decreased with the chamber volume becoming bigger; increased with the engraving pressure increases; the maximum pressure increases while the velocity decreases with the mass of the projectile increases. In order to improve the interior ballistic performance, these loaded conditions must be paid attention.

Abstract: Cognitive Radio Networks is an effective technology and a hot research direction which can solve the problem of deficient resource and revolutionize utilization. In order to enhance the communication efficiency, secondary users are classified by some strategy. We exploit the queuing theory model to research on the communication performance of secondary users, considering primary user as the first grade user and secondary users as other grades users. The research results indicate that the users which have lower priority level are more sensitive than those have higher priority level when primary user appears. Under Primary User Emulation Attack (PUEA), if the number of secondary users reaches 300, the waiting time would larger than 15 minutes. And if the appearance rate of PUEA reaches 4, the break-out rate would be 80%, which is much harmful for CRN.

Abstract: Software protection technology is necessary for software security and property right of software. The algorithm of code obfuscation based on class is proposed that uses of obfuscation technology. The overall architecture of the system is hidden by changing the class diagram for class aggregation, and the algorithm of class aggregation can be used to design class hierarchy in object-oriented program. It makes static analysis difficult while preserving function of program. The interfaces replace original classes to achieve reference in order to implement type hidden, and automatic analysis becomes more difficult.

Abstract: Gas flow is a complicated process in the condition of active manometry, we can build a gas flow model on the base of coal seam gas flow theory and math calculation. Through this gas flow model, we can get the traits of gas flow in coal seam around borehole.

Abstract: Based on the most advanced reliability engineering concept, the paper explored a cost-effective RET testing method aiming to solve the defects found in early design, manufacturing process and components. Three cases were presented in this paper that demonstrated the complete process of how to stimulate and eliminate defects. The solid firsthand case analysis has yield valuable experiences that could benefit electronic products reliability enhancement testing.