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In the drilling process of Tarim Oilfield, a representative of ultra-deep oil and gas reservoirs, there are many problems of wellbore stability/instability caused by the development of a large number of micro-fractures. According to the nano-plugging mechanism, rigid nano-SiO2 and deformable nano-paraffin emulsion are added to the drilling fluid to improve the plugging rate. The effect of nanomaterials on the mechanical properties of limestone in the Karatal Formation was evaluated through a triaxial mechanical experiment, and it was found that rigid nano-SiO2 can have a better plugging effect under high formation pressure. It can increase the compressive strength of the limestone core by 10.32% and the cohesion of the core by 12.19%, and the internal friction angle of the core was increased from 25.67° to 26.39°. The internal structure of the core after nano-blocking was observed using CT scanning, and the fracture distribution state of the core before and after plugging and the fracture characteristics of the core under the pressure gradient were obtained, which confirmed that nano-SiO2 can effectively solve the fracture problem of deep limestone caused by micro-fractures.

Traditional surface permanent magnet synchronous motor (SPMSM) used as a servo motor limits the miniaturization and performance improvement of industrial robot, due to its large overall volume and heavy weight of the rotor. In this article, a novel transverse flux permanent magnet motor with a hybrid stator core and disk-type rotor (HSDR-TFPM) is proposed to adapt to the industrial robot well. Moreover, a better space design by which the usual components used in industrial robot is considered. Considering the computing time and accuracy, an analysis method based on Schwarz–Christoffel mapping is employed to analyze the magnetic field of HSDR-TFPM and conduct research on motor parameters. In order to prevent the axial movement of rotor, the detailed mechanical design is introduced and the strength of motor is analyzed further. In the end, the analysis results and performance of the proposed HSDR-TFPM are validated and compared with a conventional servo SPMSM.

A novel Halbach permanent magnet array with rectangle section and trapezoid section is proposed and optimized in this paper. The analytical model of the premanent magnet segment is established based on the surface current method, which is numerically efficient and can be utilized to evaluate the magnetic field closely with the premanent magnet segment’s configurations. The analytical model of the Halbach array is acquired based on the superposition principle and coordinate transformation. The fundamental component of the magnetic flux density and the sinusoidal distortion rate are chosen as the optimization object. And the optimization is executed on the Halbach array with one specific set of dimensions by the genetic algorithm in global scale. The effectiveness of the optimization is validated by the finite element analysis. Compared to the traditional Halbach array with rectangle section, the magnetic field created by the optimized proposed Halbach array in this paper owns better performance.

Background Adverse Drug Reactions (ADRs) are of great public health concern. FDA-approved drug labeling summarizes ADRs of a drug product mainly in three sections, i.e., Boxed Warning (BW), Warnings and Precautions (WP), and Adverse Reactions (AR), where the severity of ADRs are intended to decrease in the order of BW > WP > AR. Several reported studies have extracted ADRs from labeling documents, but most, if not all, did not discriminate the severity of the ADRs by the different labeling sections. Such a practice could overstate or underestimate the impact of certain ADRs to the public health. In this study, we applied the Medical Dictionary for Regulatory Activities (MedDRA) to drug labeling and systematically analyzed and compared the ADRs from the three labeling sections with a specific emphasis on analyzing serious ADRs presented in BW, which is of most drug safety concern. Results This study investigated New Drug Application (NDA) labeling documents for 1164 single-ingredient drugs using Oracle Text search to extract MedDRA terms. We found that only a small portion of MedDRA Preferred Terms (PTs), 3819 out of 21,920 or 17.42%, were observed in a whole set of documents. In detail, 466/3819 (12.0%) PTs were in BW, 2023/3819 (53.0%) were in WP, and 2961/3819 (77.5%) were in AR sections. We also found a higher overlap of top 20 occurring BW PTs with WP sections compared to AR sections. Within the MedDRA System Organ Class levels, serious ADRs (sADRs) from BW were prevalent in Nervous System disorders and Vascular disorders. A Hierarchical Cluster Analysis (HCA) revealed that drugs within the same therapeutic category shared the same ADR patterns in BW (e.g., nervous system drug class is highly associated with drug abuse terms such as dependence, substance abuse, and respiratory depression). Conclusions This study demonstrated that combining MedDRA standard terminologies with data mining techniques facilitated computer-aided ADR analysis of drug labeling. We also highlighted the importance of labeling sections that differ in seriousness and application in drug safety. Using sADRs primarily related to BW sections, we illustrated a prototype approach for computer-aided ADR monitoring and studies which can be applied to other public health documents. Electronic supplementary material The online version of this article (10.1186/s12859-019-2628-5) contains supplementary material, which is available to authorized users.

The southwest area of Tarim has good potential for exploration and development, but the geological conditions of Yingsha block are complicated and complex conditions occurred frequently in drilling operations. There were 11 times lost circulation, which ranged from N2a to E1a and the lithology ranged from mudstone and sand-mudstone interbeds to gypsum rock, and the drilling cycle is up to 719 days, which seriously restricts the exploration and development of oil and gas resources. In this paper, the rock mineral composition and physical and chemical characteristic profiles of the whole well have been established for the well drilled in this area. The characteristic profiles show that quartz (21.4%~57.4%) and clay minerals (17%~44.9%) are the main layers in the lower strata (5069 m-7015 m) drilled in Yingsha. The clay minerals are dominated by illite (58%~85.75%) without smectite. The highest proportion of illite/smectite formation is 25%, the highest expansion rate is 23.87%, and the lowest recovery rate is 3%. Therefore, the stratum has strong hydration and dispersion characteristics. The average porosity of 4064 m-6666.5 m is 1.86%-6%, and the formation cracks are well developed. The wellbore instability mechanism in Yingsha is the good physical property of the sandstone, the development of cracks and micro-cracks in the lower strata, the broken strata, and the strong hydration and dispersion ability. The performance evaluation of KCL-Polysulfonate drilling fluid used in Yingsha shows that the recovery rate increases to more than 80% when the amount of KCL is 7–10%. With the introduction of paraffin nano-emulsion, the filtration loss is reduced by 30%, and the inhibition and plugging performance of drilling fluid is further improved.

In order to increase structure compactness, critical rotor speed and output torque of existing 12/12 bearingless switched reluctance motor(BSRM) with axial biased permanent magnet(PM), an improved modular permanent magnet bearingless switched reluctance motor(PM-BSRM) is comprehensively investigated. At first, this paper introduces design structure, and generation mechanism of torque and suspending force. Secondly, there is full consideration for this paper to design motor parameters, including several pole arc and rotor structure, which can fulfil some requirements such as self-starting capability, suspending force maximum value and selection of secondary air-gap. Thirdly, characteristic such as output torque and suspending force of proposed motor and others are mainly analysed. Finally, according to above analysis and research about motor characteristics, a prototype motor is designed. And through experiments, it could be found that the motor performance gets improved.

in this paper, an improved modular switched reluctance motor (SRM) is proposed with permanent magnets (PMs), located in stator yoke. This motor is a two-phase 8/10 SRM. Its stator consists of two E-Cores and two T-Cores, which are in staggered arrangement. The three poles of each E-Core are featured by one common pole in the middle and two excitation poles on the sides. Each T-Core is characterized by one common pole with two permanent magnets in two side stator yokes. All common poles have no windings. In order to analyze proposed motor, its feature is comprehensively introduced. For better illustrating the characteristic and improvements, it is compared with conventional SRM with the same sizes by means of finite element simulation. Some parameters such as average torque, output power and efficiency are compared. It is shown that proposed motor has better performances. Finally, experimental verification is performed to validate design and operation of proposed motor.

In this paper, a three-phase switched reluctance motor (SRM) controller is designed to solve the problem of large torque ripple and narrow high efficiency area for electric vehicle. Firstly, according to the linear model of switched reluctance motor, the starting control strategy based on Hall state is proposed which can make the starting torque of motor as large as possible. At low speed, the current chopper control (CCC) strategy based on current distribution coefficient is adopted to make the instantaneous torque of three-phase output approximately equal and reduce the torque ripple. At high speed, the angle position control (APC) method is adopted. The opening angle is adjusted according to the speed PI, and the turning off angle is determined by experiment according to the principle of optimal efficiency. Finally, the advantages of the designed drive system are verified by testing the dynamometer of the experimental prototype.

The development of industrial manufacturing requires higher control accuracy of industrial robot servo control system. However, in actual industrial processing, when the load moment of inertia changes, the speed of permanent magnet synchronous motor (PMSM) for industrial robot will vibrate, which will seriously affect the steady-state and dynamic performance of the control system. In this paper, firstly, the inertia analysis model is established, and the model reference adaptive identification (MRAI) method is designed to identify the moment of inertia, and then the fuzzy rules are established to identify the identification gain Finally, Matlab/Simulink simulation experiment is carried out to prove the effectiveness of the proposed method.

in this paper, a braking capability feedback control strategy for hybrid power is designed according to the braking strength. Firstly, the brake strength is determined according to the stroke of the brake pedal and then the total braking demand is calculated. Then, according to the different strength of the energy feedback, braking control strategy for friction braking and motor regenerative braking force distribution. Then according to the requirements of braking stability, the control strategy of the front and rear wheel braking force is formulated. Finally, the simulation is carried out with Simulink joint cruise to verify the feasibility of this strategy to improve efficiency.

Switched reluctance motor has its inevitable torque ripple problem due to its unique structure and severe saturation of magnetic circuit, which affects its industrial development. The traditional current chopping control cannot track the speed deviation well, and the effect of suppressing the torque ripple is not obvious. Therefore, this paper designs a current chopping controller based on fuzzy logic rules, which achieves the purpose of reducing torque ripple more effectively by controlling the PWM on/off duty cycle of each interrupt period. The effectiveness of this strategy is verified by MATLAB / SIMULINK simulation model and experimental platform with three-phase 6/4 SRM. Results show that the proposed strategy can effectively reduce torque ripple and output a constant torque.

When the load moment of inertia changes in the permanent magnet synchronous motor (PMSM) for industrial robots, the motor speed will oscillate, which will have a serious impact on the steady-state and dynamic performance of the control system. This dissertation takes the PMSM servo system for industrial robots under time-varying moment of inertia as the research object. First, a moment of inertia analysis model is established, and a moment of inertia identification method based on Model Reference Adaptive Identification (MRAI) is designed. Then use the identified moment of inertia to design the parameter self-tuning of the speed controller, and introduce the concept of "active damping". Finally, the performance of the designed control system is simulated by Matlab/Simulink, and the load experiment is carried out, which proves that the method has good anti-load interference performance.

The two-dimensional model of SRM is established in the Rmxprt module of Ansoft electromechanical system, and the simulation is performed in Rmxprt to obtain the curve of the speed, torque and current of the switched reluctance motor; importing the model to Maxwell2D, mading relevant settings such as model grouping, material settings, boundaries and excitation source settings, made a finite element analysis based on static field, obtained the motor torque characteristic curve, inductance characteristic curve, magnetization characteristic curve. The characteristics of the motor at different times are analyzed through the simulation model, which provides an effective theoretical basis for the subsequent control analysis of the motor.

The biggest limitation of wireless sensor networks is the limited energy of nodes.In order to balance the network load and prolong the network life cycle, this paper proposes a clustering routing protocol based on LEACH-GAF algorithm. This algorithm is optimized based on the classical LEACH and GAF algorithms. Firstly, this paper makes reasonable assumptions about the network model to be established, and establishes a mathematical model for the energy consumption loss of each node in the network. Secondly, the classic LEACH and GAF algorithms are analyzed to pave the way for the following simulation of LEACH-GAF algorithm. Next, the idea of LEACH-GAF algorithm is expounded,GAF algorithm is applied to divide all nodes into regions at the beginning of each round, and then LEACH algorithm is applied to randomly select cluster heads with equal probability in each region, and then the algorithm flow continues according to the classic LEACH algorithm. Finally, the LEACH algorithm and LEACH-GAF algorithm are simulated by MATLAB, and the iteration rounds of the first dead node, the overall span of node death and average residual energy consumption of all nodes are compared between the two algorithms. It is found that the network model using LEACH-GAF algorithm has longer life cycle and better energy consumption balance than the model network using LEACH algorithm.