Publications

Improving the rock-breaking efficiency of hard rock formation has always been of concern in drilling. Compound impact drilling technology is a new method to achieve efficient crushing of hard rock by exerting axial and torsional impacts on the drilling bit. In this study, to investigate the dynamic rock-breaking process and mechanism under compound impact, a numerical model was developed based on cohesive elements. Dynamic impact tests on sandstone were conducted to verify the effectiveness of the method. Then, the dynamic rock-breaking process under compound impact was simulated using the proposed model. Finally, the effects of impact parameters and cyclic loading on the rock-breaking performance were systematically studied. The results indicate that the stereoscopic crushing effect of rock can be achieved under compound impact. The amount of broken rock increases with the increase in the impact load amplitude and impact loading times, whereas both the impact angle and duration have an optimal range. When the impact angle is 30°, the impact duration is 2.5 ms, the amount of broken rock is maximum. A novel compound impact drilling tool was designed based on the analysis of the rock-breaking mechanism, the laboratory and field tests were carried out and the parameters were optimized.

The multi-state weighted k-out-of-n system model can illustrate the performance and reliability/availability relationship between components and system so that attracted more and more attentions in recent years. Under the condition that the state probabilities of components are dynamically changing with time, this paper presents a generalized instantaneous availability model for multi-state weighted k-out-of-n systems and an efficient Genetic Algorithm (GA) is proposed to compute optimal reliability and performance design values for components. Firstly, a Universal Generating Function (UGF) approach is developed to efficiently determine the availability of system assuming the state probability distributions of multi-state components follow the non-homogeneous continuous time Markov process. And then, taking into consideration of availability and cost constraints respectively, two design optimization models are set up to obtain the optimal design solutions for component via improved GA. Finally, an example analysis of transportation systems in a naval shipyard is shown to demonstrate effectiveness of the proposed model. Our results show that the improved GA can enhance the applicability of design results and conclusions of our paper can provide clear policy recommendations for design optimization of multi-state weighted k-out-of-n system.

Neurogenic lower urinary tract dysfunction (NLUTD) is a frequent consequence of spinal cord injury (SCI), leading to symptoms that significantly impact quality of life. Although many life-saving techniques are available, current treatment strategies for managing NLUTD still exhibit limitations and drawbacks. Here, we introduce a new electrical neuromodulation strategy involving electrical stimulation of the major pelvic ganglion (MPG) to initiate bladder contraction, in conjunction with innovative programmable (IPG) electrical stimulation on the pudendal nerve (PN) to induce external urethral sphincter (EUS) relaxation in freely moving or anesthetized SCI mice. Furthermore, we conducted the void spot assay, and cystometry coupled with EUS electromyography (EMG) recordings to evaluate voiding function, and monitor bladder pressure and EUS activity. Our findings demonstrate that our novel electrical neuromodulation approach effectively triggers coordinated bladder muscle contraction and EUS relaxation, effectively counteracting SCI-induced NLUTD. Additionally, this electrical neuromodulation method enhances voiding efficiency, closely resembling natural reflexive urination in SCI mice. Thus, our study offers a promising electrical neurostimulation approach aimed at restoring physiological coordination and potentially offering personalized treatment for improving voiding efficiency in individuals with SCI-associated NLUTD.

The paper introduced the current methods used in toughing cyanate ester resin(CE),analyzed the toughing mechanism,toughing effect and characteristic,and pointed out the development of cyanate ester resin.

During the ejection process of the fighter pilot, the parachute is shot out by the life-saving seat gun, which generates a shockwave that endangers human safety. In order to accurately and stably extract the time-frequency distribution characteristics, the shockwave signal is obtained through parachute gun shooting experiments, and features of the shockwave signal is extracted by using Variational mode decomposition and Hilbert transform methods (VMD-HT). VMD is a high sampling rate shockwave signal decomposition technique, which is suitable for analysing unsteady airborne parachute gun shooting shockwave signals. The HT method is used to accurately extract the relationship between time, instantaneous frequency and energy for the decomposed signal, and to obtain the marginal spectra. The analytic results show that the shockwave signal lasting 3ms has a significant energy concentration in the low frequency band of 0∽1kHz, which is important for the better protection of pilots.

As a new type of active control technology, plasma synthetic jet (PSJ) is designed to object the poor robustness of traditional synthetic jet technology. It can produce high velocity jet by electrical power. This paper presents the experiment and numerical study of PSJ actuator. The experiment study characterizes the electricity transformation when the actuator works. Numerical simulation presents the velocity changes at different discharge durations and different discharge temperatures.

Transition metal phosphides (TMPs) are considered as a promising anode material for LIBs due to their potential high theoretical capacity, suitable lithiation potential and low polarization, but low conductivity and severe volume expansion limit the performance of TMPs. Since metal‐organic framework (MOFs)‐derived materials can inherit the advantages of MOFs, MOFs‐derived metal phosphides have been widely used as anodes for LIBs and exhibit outstanding electrochemical performance. The MOFs derivatization strategy can be used to achieve the adjustment and optimization of the components and structure of metal phosphide composites, such as constructing rich heterojunction structure or designing stable carbon skeleton structure. These modifications effectively improve the electronic structure and structural stability of metal‐phosphide composites, thus solving the current problems of TMPs. In conclusion, this paper systematically summarizes the basic strategies for the modification and preparation of TMPs applied to the field of energy conversion and energy storage from the phosphorus source used in the preparation of TMPs, and finally compares the preparation methods, modification and lithium storage properties of monometallic/bimetallic phosphides derived from MOFs, and looks ahead to the characteristics and possible future development of the metal phosphides obtained by derivatization of MOFs as precursor.

To meet the high power usage requirements,coupled in series using the structural approach.By a large number of simulation and optimization,given the way that affect the structure of the key size factor.And,The combiner is produced according to the simulation results.Finally,through the test of artifactitious sample,the good result similar to the value of simulation is acquired.