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As an unconventional natural gas resource, coalbed methane has huge reserves in China and has good prospects for exploitation. During the coalbed methane extraction process, a large amount of coal powder is produced. Coal powder accumulates in fissures and blocks them, which is one of the important factors affecting the permeability of coalbed methane. A hydraulic fracturing system with adjustable frequency pulsation and single-slit filling prefabricated samples were developed for testing coalbed fissure unblocking. Experiments were carried out to study the evolution process of the unblocking pressure and the unblocking effect of pulse action under different frequency conditions. Results show that the evolution process of the unblocking pressure can be divided into three stages: pressure rise phase, decline phase, and pressure fluctuation stability phase. Compared to that, under a steady flow, the pressure threshold under the pulse action is lower, pressure drop duration is shorter, and pressure drop amplitude is smaller. The migration of pulverized coal under the action of steady flow is concentrated in the pressure drop stage. Under the action of pulsating pressure, pulverized coal migrates in the pressure drop stage and the pressure fluctuation stable stage. The pressure drop time is positively correlated with the total amount of pulverized coal transported, but the total transport volume of pulverized coal is equivalent to that under the action of steady flow. The fluid infiltration along the radial direction mainly occurs during the pressure rise to the peak pressure. The filtrate penetration radius is smaller due to the shorter unblocking time under the pulsating flow, and the reservoir damage is small. Comprehensively considering the unblocking pressure, coal migration, unblocking seepage path, and unblocking seepage depth, especially the unblocking pressure and unblocking seepage depth, as the main evaluation factors, the best unblocking effect is under the condition of 3 Hz, which has a lower solution.

Jiaguyou 404 was a new combination of high-quality hybrid rice bred by Quanzhou Institute of Agricultural Sciences, which was bred by crossing Jiagu A, a three-line sterile line with good quality and disease resistance, as the female parent and Quanhui 404 as the male parent. The combination had the characteristics of good plant-leaf shape, large panicle and multiple grains, moderate plant height and plant type, high and stable yield, and good rice quality, which was examined and approved by Fujian Crop Variety Approval Committee in 2022. The breeding process, characteristics, high-yield cultivation and seed production technologies of the new hybrid rice combination, namely Jiaguyou 404 were introduced . [ABSTRACT FROM AUTHOR]

Greedy link scheduling based on the physical model was studied in a static wireless network with SIC.In general,there were two major stages in a greedy scheduling scheme,link selection,i.e.,to decide which link was scheduled next,and time slot selection,i.e.,to decide which slot was allocated to a given link.Most available schemes took a first-fit policy in the second stage and became less efficient when SIC was available.For the time slot selection stage,tolerance margin was defined to measure the saturation of a link set and two heuristic policies were presented:one was to schedule a link to a slot such that the resulting set of links had a maximum tolerance margin; the other was to choose a slot such that the decrease of tolerance margin was minimum.Simulation results show that the performance of the proposed schemes is much better than the first-fit policy.

As jamming attack can interrupt signal decoding and severely reduce communication performance, an adaptive rateless communication mechanism is proposed to reduce the interference effect of jamming attack. With the help of rateless codes, a packet is split into multiple encoded micro-packets and then transmitted independently, which can reduce the impact of interference and take advantage of the non-contiguous available channel. By adaptively adjusting the length of the micro-packet, better robustness can be achieved by using a smaller length when the attacks occur frequently. Meanwhile, high efficiency can be obtained by increasing the micro-packet length when attacks occur rarely. Experimental results show that, in comparison with direct transmission, rateless transmission can improve the throughput by 50% on average, and the stability by an order of magnitude. In summary, rateless communication can effectively rateless jamming attacks and achieve high communication efficiency. [ABSTRACT FROM AUTHOR]

The impact acceleration curves and impact mechanism of the ball-firing-strength test are analyzed and studied for improving the strength test methods of aiming devices for weapon systems, based on which an integrative impact and vibration system with continuous impact capability and high acceleration value is designed instead of ball firing for strength test of aiming devices of weapons systems. In the strength test of optical sight of a certain small arms, 710 bullets and test cost of RMB 284 thousand have been saved by using this system, which solves the problems of high cost and low efficiency of test to achieve pretty well economic benefit. [ABSTRACT FROM AUTHOR]

Screening out the safety-related substances and establishing the corresponding standard has been a key research issue to improve the safety of traditional Chinese medicine injections(TCMIs). 5-HMF which widely exists in sugar-containing TCMIs has long been considered as an important safety-related substance. In this review, we summarizes the research progress on the toxicology of 5-HMF as well as the content and standards of 5-HMF in TCMIs.Therein, both literature summary and analysis results indicate that there are lack of toxicology researches of 5-HMF and its metabolites in TCMIs, although the potential toxicity of 5-HMF and its metabolites has been reported. Moreover, the content of 5-HMF largely varies from TCMIs to TCMIs, and even in the same TCMIs from different factories. To ensure the clinical efficacy of TCMIs, it urgent to carry out the study of the toxicology of 5-HMF in TCMIs comprehensively and systematically, so as to set up a relatively uniform standard as well as to develop process quality control method., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Chinese Pharmaceutical Association.)