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The underbalanced drilling has been widely used due to its advantages of high drilling efficiency and low cost etc., especially for hard formation drilling. These advantages, however, are closely related to the stress state of the bottom-hole rock; therefore, it is significant to research the stress distribution of bottom-hole rock for the correct understanding of the mechanism of rock fragmentation and high penetration rate. The stress condition of bottom-hole rock is very complicated while under the co-action of overburden pressure, horizontal in-situ stresses, drilling mud pressure, pore pressure and temperature etc. In this paper, the fully coupled simulation model is established and the effects of overburden pressure, horizontal in-situ stresses, drilling mud pressure, pore pressure and temperature on stress distribution of bottom-hole rock are studied. The research shows that: in air drilling, as the well depth increases, the more easily the bottom-hole rock is broken; the mud pressure has a great effect on the bottom hole rock. The bigger the mud pressure is, the more difficult to break the bottom-hole rock; the max principle stress of the bottom-hole increased with the increasing of mud pressure, well depth and temperature difference. The bottom-hole rock can be divided into 3 regions respectively according to the stress state, 3 direction stretch zone, 2 direction compression area and 3 direction compression zone; the corresponding fragmentation degree of difficulty is easily, normally and hardly.

How to identify the fault causes quickly and improve the efficiency of maintenance, which can reduce the fault disaster, has always been one of the key problems in equipments fault diagnosis. In this paper, a new qualitative fault diagnostic approach based on control change cause analysis (3CA) is proposed to identify the fault causes and fault risk index, which can be utilized to control the risk of equipment fault. We employed an existing method that was events and conditional factors analysis (ECFA+) to identify the analysis objects of 3CA, and put forward integrated methods including first principle-best practices approach, barrier failure analysis and prioritization rating code (PRC) matrix to accomplish control analysis, change analysis and significance rating of 3CA respectively, and those technical methods could be used to build the procedure diagram of identifying the content in each column of 3CA worksheet. According to the procedure of 3CA, we built a worksheet of 3CA for a vehicle engine fault, then fault causes and significance rating on behalf of the rating of fault risk index were determined. Meanwhile fault risk index had also been used to rank the fault causes, accomplishing fault diagnosis and verifying the availability or this method for fault diagnosis. The proposed approach can be able to identify fault causes of different fault modes that they have different risk index, and provide the fault causes rating that is the foundations of troubleshooting, which can mitigate and control fault disaster.

[abstFig src='/00280005/03.jpg' width='300' text='Speed impact on minimum total loss control' ] Increasing motor operating efficiency potentially reduces energy consumption and radiator requirements. In some applications, the motor’s operating efficiency may even be the most important factor to be considered. The model-based minimum total loss control (MTLC) we proposed could potentially improve motor efficiency by taking copper and iron loss into account based on the motor model, finding the minimum power point, and enabling the permanent magnet synchronous motor achieve optimal efficiency at different speeds. Copper loss under MTLC increased less than the maximum torque per ampere (MTPA), but iron loss under MTLC was much lower than MTPA, reducing total loss. MTLC reduced total loss by adjusting the relation between copper and iron loss using a demagnetization current. Analysis and simulation results show that our proposal improved the efficiency of the permanent magnet synchronous motor effectively, making it easy to implement in practical control with little calculation.

Shortest path experiment device The avoidance obstacle path planning problem is stated in an obstacle environment. The minimum Steiner tree theory is the basis of the global shortest path. It is one of the classic NP-hard problem in nonlinear combinatorial optimization. A visualization experiment approach has been used to find Steiner point and system’s shortest path is called Steiner minimum tree. However, obstacles must be considered in some problems. An Obstacle Avoiding Steiner Minimal Tree (OASMT) connects some points and avoids running through any obstacle when constructing a tree with a minimal total length. We used a geometry experiment approach (GEA) to solve OASMT by using the visualization experiment device discussed below. A GEA for some systems with obstacles is used to receive approximate optimizing results. We proved the validity of the GEA for the OASMT by solving problems in which the global shortest path is obtained successfully by using the GEA.

The industrial structure of the cities has undergone great changes, while the population is also in a large number of flows, which undoubtedly makes Chinese urban transportation construction and management face new standards and challenges. We proposed using immune algorithm to solve the transportation planning problems in this paper to shorten the total length of transmission network and transportation network, and developed a MATLAB software with the immune algorithm procedures to solving the engineering problems. By running MATLAB program got 5 substation construction points and 2 urban rail construction centers, the results showed that it can shorten the path and reduce the cost of investment to a certain extent, and the immune algorithm has global optimization, parallel search, high efficiency and other characteristics. Through the verification of the northeast transmission network optimization analysis and the central plains urban agglomeration intercity rail transportation network planning optimization analysis, demonstrated the feasibility and effectiveness of the immune algorithm.

An approximation method for calculating inverter power loss is proposed for SVPWM widely used in the electric vehicle drive system. Losses in the different vector sectors are calculated separately according to the characteristics and parameters of the IGBT in the loss approximation method. After that, for id=0 control and MTPA control of the permanent magnet synchronous motor, the power losses are calculated respectively and compared. This approximation method provides a theoretical basis for the selection of the appropriate power module and the rational design of cooling devices for the inverter

Engine is the power source and the heart of the vehicle and it can ensure the safety and reliability of the whole vehicle dynamic system. Engine structure is becoming more and more complex, and it is difficult to make fault diagnosis after fault happened. In order to complete engine fault diagnosis quickly and accurately, in this paper, a new method of cause analysis has been proposed to make fault diagnosis, and this method is control change cause analysis (3CA). 3CA is a method which can be used to the cause analysis of different types of accidents and faults. 3CA is based on the process of control analysis and change analysis. Applying control change analysis to analyze engine fault can get the barrier and control which can prevent the fault happening again, the change of the engine performance and the importance ranking of the fault phenomenon, which provides a basis for the cause analysis of the fault.

The dynamic mechanics model was built up to analyze the contact-impact between drill string and wellbore according to the characteristics of contact-impact, based on non-linear finite element method and Lagrange method. The dynamic mechanics equations were deduced by the dynamic mechanics model. The stress and deformation field of drill string with different parameters of bottom hole were obtained and tested by experiments and numerical simulation respectively. And also, the propagation laws of stress wave generated by contact-impact in drill pipe were studied. The comprehensive results indicate that the numerical results agree well with the actual dynamic process of contact-impact. The stress waves generated by contact-impact cause the change of stress. The contact-impact between drill string and wellbore under air drilling is the main reason for early drill string failure.

The first excursion failure criterion was introduced to calculate the dynamic reliability of drill string elements. Considering the random of geometry size and mechanical property parameters of drill string in deep & ultra-deep wells, the drill string system was dispersed into several basic elements according to the structure, strength and differences in the nature of formation rock in the well depth direction. And the overall dynamic reliability was quantitatively calculated through the serial theory. Through an example, the results show that the dynamic reliability of the drill string elements appeared fluctuation near the depth of 4500 meters for the inside worn of the drill string and casing, and uneven loading of drill string. The dynamic reliability of drill string in deep and complicated formation was less than any other drill strings. The drilling pressure, rotation speed and drilling depth were the main influencing factors on the dynamic reliability of drill string.

Increase the operating efficiency of the motor can reduce energy consumption and the requirements for the radiator, for some applications, the operating efficiency of the motor even become one of the most important factors. In order to improve the efficiency of the motor, in this paper, the maximum efficiency permanent magnet synchronous motor control method was proposed, the method takes into account the copper and iron losses based on the motor model, and can make a permanent magnet synchronous motor to achieve optimal efficiency at different speeds by the way of look-up table. The proposed method reduces the amount of computation greatly, and it is easy to implement in practical control. The simulation results showed that the method can improve the efficiency of permanent magnet synchronous motor effectively.