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The drilling effect of complex and weak coal seams is of great significance for gas extraction in mines. A ZDY6000LR high-speed tracked drilling rig with high rotational speed, high power, and high torque performance was designed to address the problems of difficult slag removal, high accident rate, and hole formation during the drilling construction of complex and weak coal seams in Wangpo Coal Mine. The maximum torque was 6 000 N·m and the maximum speed was 400 r/min. The layout, power head, angle adjustment mechanism, feed body, and hydraulic system of the drilling rig were optimized to ensure that the problems such as sticking and collapsing during the drilling process can be effectively solved during the construction process. The ϕ95/ ϕ60.3 mm wide blade insert sealed auger rod with high strength and not easy to break teeth is developed and designed, and the ϕ113 mm, ϕ120 mm, ϕ133 mm triangular ladder PDC bits with high strength and low risk of broken teeth are also designed. The on-site industrial test at the 3206 working face of Wangpo Coal Mine has shown that this set of drilling equipment and drill assembly effectively solved the problems existing in the construction process such as slag discharge difficulty and top drilling of the jet hole, and improved the hole formation rate of the drilling, and the hole formation rate of the drilling above 100 meters was more than 70%, which provided an important support for the gas extraction of the coal seam of the mine.

Although power electronic converters have been the key enablers for the the integration of renewable generation, heterogeneous controllers and lower inertia increase the complexity of microgrids, more likely to cause instability. Hence, it is significant to study the stability of microgrids using prospective modeling tools such as, bode plots, Nyquist plots, eigenvalue loci, etc. The modeling of microgrids is an important step of stability analysis, where state-space-based and impedance-based modeling are the two commonly used stability evaluation approaches in microgrids. Miscellaneous modeling methods have respective pros and cons, which have been investigated in the existing literatures to some extent. However, it is still critical to quantify the modeling techniques so as to formalize the stability validation in an intuitive way, which is not addressed in existing literatures. Therefore, in this paper, modeling methods for stability validation are mapped based on an order-indicated complexity, and a quantitative framework for the mapping is provided. The proposed framework can be instructive when modeling microgrid systems with different sizes, topologies or control strategies, etc., and it turns out to be well applicable as demonstrated by exemplified simulations and experimental tests.

To solve the abuse of the Android application permission mechanism, a method of Android application access control based on virtual machine bytecode injection technology was proposed.The security policy in the form of virtual machine bytecode was generated according to the user’s security requirement and usage scenario, and injected into the coding unit of Android application that involves dangerous permission request and sensitive data access, to realize dynamic application behavior control.Tests on applications crawled from four mainstream domestic App stores show that the method can effectively intercept sensitive API calls and dangerous permission requests of legitimate App programs and implement control according to pre-specified security policies.Also, after injecting virtual machine bytecode, most of the App program operation is not affected by the injected code, and the robustness is guaranteed.The proposed method has a good universality.

In order to solve the problems of privilege sensitivity protection and the abuse of authorization by the agent when the device owner delegates authorization in IoT devices sharing environment,a trust-based delegation mechanism for controllable partial permissions was proposed with the trust access control model and the proxy signature.This mechanism generates trust values and authorization policies based on the relationship between the users,and implements controllable partial authority delegation through the proxy signature.According to the security analysis,the mechanism can meet the security attributes such as verifiability,non-repudiation,distinguishability,identifiability and non-abuse required by the permission transfer,and ensure the controllable security transfer of the device owner's permission.The problem of over authorization of an intermediary agent is effectively prevented.

Structural health monitoring (SHM) is essential when detecting damage in large and complex structures in order to provide a comprehensive assessment of the structural health state. Optimal sensor placement (OSP) is critical in the structural health monitoring system, which aims to use a limited number of sensors to obtain high-quality structural health diagnosis data. However, the current research mainly focuses on OSP for structures, without considering the values contributed by different modes to the bridge structure. In this article, an optimal sensor placement method based on initial sensor layout, using the dynamic adjustment of attenuation factor gravitational search algorithm (DGSA), is proposed. The effective modal mass participation ratio is introduced to ensure the validity of the initial data of optimal sensor placement. In view of the insufficient developmental ability of the gravitational search algorithm, the attenuation factor α adjusted dynamically aids the global search in the early iteration and the local fine search in the late iteration. The double coding method is used to apply the DGSA algorithm to OSP; taking cable-stayed bridges as an example, the feasibility of the algorithm is verified. The results show that the improved algorithm has a good optimization ability and can accurately and efficiently determine the optimal placement of sensors.

The most problem in analysis of communication protocols and communication data for mobile terminals is that many mobile applications do not have the relevant public technical documents,and it is difficult to know the type of communication protocol it adopts.The instruction execution sequence analysis technique takes the instruction sequence executed by the program as a research object,and inversely infers the message format and the state machine to obtain the communication protocol.However,due to the incomplete collection of sequence information,the state machine infers that the inference is incomplete and cannot be effective.A novel protocol reverse scheme based on state machine comparison is proposed,which can be used for the forensics of mobile terminal communication data.The scheme first uses PIN for dynamical identification of the taint,and track it and analyzes the trajectory to obtain the message format.Secondly,the message clustering is performed on the basis of the message format to infer the protocol state machine.Finally,the LCS algorithm is used to compare the state machines to get a complete protocol state machine.This article tests and evaluates the scheme based on two types of application design experiments on the Android platform.The experimental results show that the results are both complete and real-time,and have practical value.

Emergency vehicle (EV) plays an important role in evacuations or rescues when emergencies occur. To insure that an EV can transfer people in danger to emergency shelters or medical assistance organizations as soon as possible, EV signal preemption (EVSP) strategy is usually adopted. After EV has passed through the intersection, traffic signal has to transfer back to normal signal timing scheme. This paper focuses on the control strategy of EV signal transitioning from EVSP back to normal operation. Considering both efficiency and fairness, the maximum vehicles passing through in per unit time during the transition period and the minimum difference between the maximum and the minimum queue length after transition are selected as objectives, and a multi-objective optimization model is presented. A nondominated sorting genetic algorithm II (NSGA-II) is designed to solve the optimization model and unique encoding and decoding methods are presented. The established model and designed algorithm are verified and the control effect is analyzed. Simulation results indicate that by adopting the control strategy obtained by the presented model, the number of vehicles passing through in per unit time during the transition period is increased and the difference of vehicle length in different directions is reduced significantly, from which we can conclude that the control method proposed in this paper has good performance.

This paper focuses on the signal preemption control of emergency vehicles (EV). A signal preemption control method based on route is proposed to reduce time delay of EV at intersections. According to the time at which EV is detected and the current phase of each intersection on the travelling route of EV, the calculation methods of the earliest start time and the latest start time of green light at each intersection are given. Consequently, the effective time range of green light at each intersection is determined in theory. A multiobjective programming model, whose objectives are the minimal residence time of EV at all intersections and the maximal passing numbers of general society vehicles, is presented. Finally, a simulation calculation is carried out. Calculation results indicate that, by adopting the signal preemption method based on route, the delay of EV is reduced and the number of society vehicles passing through the whole system is increased. The signal preemption control method of EV based on route can reduce the time delay of EV and improve the evacuation efficiency of the system.

The automatic stereo warehouse system is a storage system with multi-storey warehouse, by which the automation access and integrated automation management are realized in the computer's direct control and management. The emerging, bypass automatic stereo warehouse has gained more and more application in rapid access. The stacker's working time directly affects the efficiency of the warehouse. To improve the bypass automatic warehouse efficiency and analyze the stacker route, an integrated optimization model considering the export selection and the path picking is established. The model aims to the picking task cycle and develops the population's generating method of genetic algorithm, then solves the optimization model. The last section in this stage is the initial point of the next optimization stage, using the nearest neighbor method to find the optimal export location. Simulation and practical application show that the model and the algorithm are feasible and effective.