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To solve the problems of small local relief range, low continuity and high operational risk of rockburst, regional hydro-fracking and burst prevention system and engineering application research were carried out within thick and hard roof of a coal seam by well over thousand meters on and under the ground. The results show that, according to the loading conditions, the roof dominated rockburst can be divided into three types: superposed dynamic and static loading type, high static loading type and high static unloading type; The thick and hard roof is the main source of regional static and dynamic loading for rock burst initiation of mining surrounding rock. With the thick and hard roof as the target, which provides the source of dynamic and static load for rock burst initiation, a segmented fracturing pressure relief system for the roof with 1000 meter horizontal holes on and under the ground was established and fracking was carried out in this area. By destroying the integrity of the overlying roof in the burst prone area in advance on and under the ground, the load is transferred to the more intact roof area, so as to provide a low stress operational environment for underground excavation and extraction, and also make the rock burst initiation conditions inapplicable. The fracking and burst control tests on the roof area using the horizontal well drilled on the ground before the extraction of the panel, and underground drilling from the entries during the extraction were carried out respectively. Remarkable results have been achieved in practice, forming a new disaster prevention and control mode of “fracking before construction” for burst prone coal mines under construction, and “fracking before tunneling, fracturing before mining” for the producing coal mines.

In order to ensure the safety of multi-roadway crossing area in the mining process of strong impact working face under hard roof, the end mining of 401111 working face of Shaanxi Binchang Hujiahe Mining Co., Ltd. is taken as the engineering background. The method of theoretical analysis and field monitoring is used to classify the rock burst hazard area of the working face during the end mining period. Moreover, the dynamic and static load influencing factors that lead to the increase of rock burst hazard are analyzed. The dynamic and static load monitoring situation during normal mining and the end mining are compared. The results show that the 401111 working face mining coal seam has strong rock burst tendency. Under the condition of hard roof, the static load is provided by the working face goaf, adjacent goaf and multi-roadway intersection area. The dynamic load is provided by the instantaneous release of elastic energy in the overlying hard roof overhanging and collapsed and multi-roadway intersection areas in the goaf. The joint action of dynamic and static loads leads to an increase in the rock burst hazard of the 401111 working face at the end of mining. And the rock burst hazard in the intersection area of the return air roadway is higher than that of the transport roadway side. The idea of separate source prevention and control of rock burst is adopted. For the overlying hard roof, the roof pre-split blasting technology is used to shorten the roof collapse step. And the dynamic load disturbance caused by the large-area overhang and collapse of the roof is reduced. For the roadway side and floor, large-diameter drilling is used to relieve pressure so as to reduce the accumulation of static load and the degree of load on the surrounding rock. At the same time, the roof of the roadway is supported by bolt+steel belt mesh and anchor cable. The side of the roadway is supported by anchor cable+steel ladder mesh so as to improve the rock burst resistance of surrounding rock. After using the rock burst prevention technology based on pressure relief and joint support, the micro-seismic events are greatly reduced. The result indicates that the coal and rock mass fracture degree is low and the integrity is good, and the safe mining of the working face is ensured.

The stress environments of gob-side roadways (GSRs) are becoming increasingly complex during deep coal mining under thick and hard roofs. This leads to strong strata behaviors, including roadway floor heave, roof subsidence, and even coal bursts. Among them, coal bursts pose the greatest threat to production safety in coal mines. Coal bursts in a GSR strongly correlate with the load characteristics and stress-energy evolution laws of the roadway. This study analyzes the roof structures of double working faces (DWFs) during the initial weighting stage (IWS) and full mining stage (FMS) of gob-side working faces (GSWFs). This study also explores how varying roof structures affect the stability of GSRs. Three-dimensional roof structure models of DWFs and mechanical models of dynamic and static loads superposition on a GSR throughout the IWS and FMS of a GSWF were developed. An analysis identified the primary stress sources affecting the GSR throughout various mining stages of the GSWF. Subsequently, the principle of "three-load" superposition was developed. A novel method was proposed to quantify the stress state in the GSR surrounding rock across different mining stages of the GSWF. The method quantitatively characterizes the load of the GSR surrounding rock. Based on this, the criterion for judging the burst failure of the roadway was established. Numerical simulations are used to analyze the stress-energy evolution laws of the working face, coal pillar, and GSR surrounding rock during the mining process of the GSWF. These findings offer valuable references for studying and preventing coal bursts in GSRs under equivalent geological situations. [ABSTRACT FROM AUTHOR]

Fusarium pseudograminearum (Fpg) is a significant pathogen responsible for fusarium crown rot (FCR) in wheat (Triticum aestivum L.), a disease with devastating impacts on crop yield. The utilization of biocontrol bacteria to combat fungal diseases in plants is a cost-effective, eco-friendly, and sustainable strategy. In this trial, an endophytic bacterial species, designated as SW, was isolated from the roots of wheat. The strain exhibited potent antagonistic effects against Fpg and reduced the FCR disease severity index by 76.07 ± 0.33% in a greenhouse pot trial. Here, 106 colony-forming units (CFUs)/mL of the SW strain was determined to be the minimum dose required to exhibit the antagonism against Fpg. The strain was identified as Bacillus atrophaeus using genome sequencing and comparison with type strains in the NCBI database. Whole-genome sequencing analysis revealed that SW harbors genes for siderophores, antifungal metabolites, and antibiotics, which are key contributors to its antagonistic activity. Additionally, the strain's ability to utilize various carbon and nitrogen sources, successfully colonize wheat root tissues as an endophyte, and form biofilms are critical attributes for promoting plant growth. In summary, these findings demonstrate the ability of Bacillus atrophaeus to control FCR disease in wheat in a sustainable agricultural setting. [ABSTRACT FROM AUTHOR]

Shipboard integrated power systems (IPS) combine a traditional marine independent mechanical propulsion system and a power system in the form of electrical energy, which is an important trend of warship power systems at present. Hence, it is necessary to have an in-depth understanding of IPS's constitution, development trends and approach to construct. Compared with land power grid, this thesis tackles the significant characteristics of shipboard IPS, probes into the researches and development tendency of relative technologies, contrasts and summarizes typical analysis and evaluation techniques of shipboard IPS, such as power flow calculation analysis, reliability evaluation and risk assessment, to provide a theoretical basis for the design, construction, operation and maintenance, management and control. It indicates that internet of things technology, 5G communication technology, multi-core CPU technology and information interaction and fusion will be effective approaches in meeting all kinds of challenge faced by the future development of shipboard IPS . Moreover, the technologies including intelligent sensing measurement, intelligent energy management, intelligent fault reconstruction, etc., will be the essential foundation of shipboard IPS, to maximize the combat capability and survivability of warship.

In order to solve the safety problem of deep intelligent mining and prevention and control personnel threatened by rock burst, an intelligent prevention and control method of deep rock burst was put forward. Based on the key role of foundational static load inducing rock burst initiation, theoretical basis of intelligent prevention and control of deep rock burst was proposed, which was to automatically detect the foundational static load of surrounding rock in mining space, and achieve intelligent and precise decrease of its concentration degree, so as to improve threshold of acquiring static load or dynamic load increment in later stage for achieving purpose of rock burst prevention and control. Development paths of researching intelligent prevention and control of deep rock burst in the future were put forward, which included active schedule theory and method of multi-source information of rock burst disaster, expert database of disaster prevention scheme based on multi-source information fusion, rapidly interactive and intelligent robot and informationized equipment, intelligent control of rock burst disaster and compound disaster self-adaption technology and effect self-evaluation technology of major disaster prevention and control.

BACKGROUND: Adjusting nitrogen (N) input based on actual seedling density (ASD) and plant N status is a practical approach for improving the yield stability of direct‐seeded rice. However, the adjustment of topdressing N rates has been empirical in the past. This study aimed to establish a quantitative approach for determining N topdressing rates during tillering (Ntil) and panicle development (NPI) based on ASD and crop N status in direct‐seeded rice. Field experiments were conducted involving 12 treatments, consisting of four Ntil and three seeding rates in 2017, and eight treatments combining seeding rate, Ntil, and NPI in 2020. RESULTS: Linear regression analysis revealed that the tiller number at panicle initiation (TILPI) was predominantly influenced by ASD and Ntil. The determination coefficients (R2) of the regression models ranged from 0.887 to 0.936 across the four‐season experiments. The results indicated that Ntil could be determined accurately using ASD and the target maximum tiller number. Similarly, grain yield was influenced significantly by the N uptake at panicle initiation (NUPPI) and NPI, with R2 of 0.814 and 0.783 in the early and late seasons of 2020, respectively. This suggested that NPI could be calculated based on NUPPI and the target grain yield. CONCLUSION: The findings offer a quantitative method for establishing N topdressing rates for tillering and panicle development, relying on the monitoring of actual seedling density and plant N status in direct‐seeded rice production. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]