Comparative Study on Sealing Technology of Gas Drainage Borehole in Soft Coal Seam

This paper discusses four kinds of hole sealing technologies for gas drainage in soft coal seam, which are polyurethane hole sealing, cement mortar hole sealing, full-length screen pipe hole sealing and pipe direct connection technology. Through the observation of negative pressure loss, the sealing effect of four sealing technologies is analyzed, the polyurethane sealing effect is poor, the cement mortar, the full-length screen pipe combined with cement mortar and the direct connection technology of pipe are good; through the observation of gas concentration, the gas drainage effect of four sealing technologies is analyzed, the polyurethane sealing technology is the worst, and the direct connection technology of pipe is the worst. The gas drainage effect is the best; according to the sealing effect and gas drainage effect, the traditional polyurethane and cement mortar sealing technology cannot meet the gas drainage demand of the soft coal seam. In the case of slow drilling deformation, the full-length screen pipe sealing technology can be used. In the case of rapid drilling deformation, the direct connection of pipe sealing technology should be used

Anisotropic nanomechanical properties of bovine horn using modulus mapping

Bovine horns are durable that they can withstand an extreme loading force which with special structures and mechanical properties. In this paper, we apply quasi-static nanoindentation and modulus mapping techniques to research the nanomechanical properties of bovine horn in the transverse direction (TD) and longitudinal direction (LD). In quasi-static nanoindentation, the horn’s modulus and hardness in the inner layer and the outer layer demonstrated a gradual increase in both TD and LD. Laser scanning confocal microscopy (LSCM) revealed microstructure in the horn with wavy morphology in the TD cross-section and laminate in the LD cross-section. When using tensile tests or quasi-static nanoindentation tests alone, the anisotropy of the mechanical properties of bovine horn were not obvious. However, when using modulus mapping, storage modulus (E′), loss modulus (E″) and loss ratio (tan δ) are clearly different depending on the position in the TD and LD. Modulus mapping is proposed as accurately describing the internal structures of bovine horn and helpful in understanding the horn’s energy-absorption, stiffness and strength that resists forces during fighting

Multi-agent-based control strategy for centerless energy management in microgrid clusters

Interconnecting microgrids with similar geographical environment and related characteristics electrically and communicatively, this constitutes a microgrid cluster, which is a higher-level distributed power structure and an effective way to improve the utilization rate of distributed energy and local absorption level. However, the stable operation of microgrid clusters is determined by the cluster structure and its control strategy, which is also the focus and difficulty of current research. To address this challenge, this paper proposes a ring-based multi-agent microgrid cluster energy management strategy, which realizes the centerless coordinated autonomous operation of microgrid clusters with high stability. In addition, based on the multi-agent control strategy, this paper designs a variety of control strategies that can be switched autonomously for different control objectives of the microgrid cluster to realize smooth grid connection and off-grid of the microgrid cluster. Finally, based on Matlab platform simulation, the experimental results show that the control structure and energy management strategy proposed in this paper can realize the centerless coordination and autonomy of the microgrid cluster on the basis of stable operation, minimize the energy interaction between the cluster and the distribution network, and greatly improve the utilization rate and local absorption level of distributed energy

Research on Biomimetic Models and Nanomechanical Behaviour of Membranous Wings of Chinese Bee Apis cerana cerana

The structures combining the veins and membranes of membranous wings of the Chinese bee Apis cerana cerana Fabricius into a whole have excellent load-resisting capacity. The membranous wings of Chinese bees were taken as research objects and the mechanical properties of a biomimetic model of membranous wings as targets. In order to understand and learn from the biosystem and then make technical innovation, the membranous wings of Chinese bees were simulated and analysed with reverse engineering and finite element method. The deformations and stress states of the finite element model of membranous wings were researched under the concentrated force, uniform load, and torque. It was found that the whole model deforms evenly and there are no unusual deformations arising. The displacements and deformations are small and transform uniformly. It was indicated that the veins and membranes combine well into a whole to transmit loads effectively, which illustrates the membranous wings of Chinese bees having excellent integral mechanical behaviour and structure stiffness. The realization of structure models of the membranous wings of Chinese bees and analysis of the relativity of structures and performances or functions will provide an inspiration for designing biomimetic thin-film materials with superior load-bearing capacity

Bio-inspirations for the Development of Light Materials based on the Nanomechanical Properties and Microstructures of Beetle Dynastes tityus

Dynastes tityus (D. tityus) is a typical beetle whose elytra are light and strong. The primary function of elytra is to protect beetle’s hindwings. In this paper, D. tityus elytra were selected as the biological prototype for the investigation to obtain bio-inspirations for the design and development of light materials with high ratio of strength to mass. Firstly, the microstructure investigation and quasi-static nanoindentation tests have been carried out on the ten samples of the selected elytra of D. tityus to reveal their mechanical properties and microstructures. Secondly, based on the findings from the microstructure investigation and nanoindentation tests, three models of bio-inspired materials have been proposed for further study to gain the deep understanding of the relationships between the special mechanical characteristics and microstructures. Then Finite Element Analysis (FEA) simulations have been performed on the three models for harvesting the bio-inspirations for the initial design of light materials. Finally, through comparative analysis of the findings from the microstructure investigation, the nanoindentation tests and the simulations, some meaningful bio-inspirations have been reaped for the future optimization of the design and development of light materials with high ratio of strength to mass

The mechanism of resistance-reducing/anti-adhesion and its application on biomimetic disc furrow opener

The black soil of Northeast China is sticky and agglomerates easily, which often adheres to the surface of a traditional furrow opener during the furrowing process. In this paper, biomimetic design principles in resistance-reducing, anti-adhesion and resistance-reducing mechanism of biomimetic disc furrow opener were studied. Nine kinds of singular convex hull, nine kinds of singular wedge and nine kinds of mixed convex hull and wedge structural biomimetic disc furrow opener were designed, and the furrowing process with the soil simulated by finite element method (FEM). Three types of biomimetic disc furrow opener with less resistance were manufactured by laser processing for comparative test in soil bin based on the simulation results. The test results showed that the resistance of the biomimetic disc furrow opener was less than that of the ordinary disc. The soil-disc stress, influence of biomimetic structures, moisture content and furrow speeds on resistance were discussed. The resistance-reducing rate of D-BC-3 reached the maximum value 15.36% at the furrow speed of 0.6 m/s and the soil moisture content of 20%. It is believed that the biomimetic design principles can provide the significant inspirations for the future design of disc furrow opener with drag reduction

A Simulation of the Flight Characteristics of the Deployable Hindwings of Beetle

An insect is an excellent biological object for the bio-inspirations to design and develop a MAV. This paper presents the simulation study of the flight characteristics of the deployable hindwings of beetle, Dorcustitanus platymelus. A 3D geometric model of the beetle was obtained using a 3D laser scanning technique. By studying its hindwings and flight mechanism, the mathematical model of the flapping motion of its hindwings was analyzed. Then a simulation analysis was carried out to analyze and evaluate the flapping flying aerodynamic characteristics. After that, the flow of blood in the hindwing veins was studied through simulation to determine the maximum pressure on a vein surface and the minimum blood flow in flight. A number of interesting bio-inspirations were obtained. It is believed that these findings can be used for the design and development of a MAV with similar flying capabilities to a natural beetle

The DNA-sensing AIM2 inflammasome controls radiation-induced cell death and tissue injury

Acute exposure to ionizing radiation induces massive cell death and severe damage to tissues containing actively proliferating cells, including bone marrow and the gastrointestinal tract. However, the cellular and molecular mechanisms underlying this pathology remain controversial. Here, we show that mice deficient in the double-stranded DNA sensor AIM2 are protected from both subtotal body irradiation-induced gastrointestinal syndrome and total body irradiation-induced hematopoietic failure. AIM2 mediates the caspase-1-dependent death of intestinal epithelial cells and bone marrow cells in response to double-strand DNA breaks caused by ionizing radiation and chemotherapeutic agents. Mechanistically, we found that AIM2 senses radiation-induced DNA damage in the nucleus to mediate inflammasome activation and cell death. Our results suggest that AIM2 may be a new therapeutic target for ionizing radiation exposure

Case report: Application of morphology in the diagnosis of siderosis in a patient with tuberculosis infection

A 49-year-old male who had been working in welding for more than 30 years was admitted to the hospital for a medical checkup that revealed a lung shadow without specific symptoms such as coughing and sputum. Imaging studies showed diffuse ground-glass changes in both lungs, wall cavities with wall nodules, multiple peripheral nodules, and some nodules with calcification. The patient has been engaged in welding work for more than 30 years and exposed to iron dust. Lung tissue biopsy, routine morphological and pathological fluid basis examination of alveolar lavage fluid, can be considered as pulmonary iron particles, which can be regarded as iron dust lung. Acid-fast bacilli were detected in both fibrobronchoscopic brush extract and alveolar lavage fluid acid-fast staining. As the pathological examination revealed granulomatous inflammation showed caseation necrosis, the patient was judged to have concomitant pulmonary TB. After the diagnosis was made, the patient was no longer exposed to dust and was treated with appropriate anti- tuberculosis (TB) therapy. Lung lesions caused by welding have been reported, but the simultaneous finding of siderosis with pulmonary TB is specific to the case presented here. By describing the imaging features, combining different staining methods of alveolar lavage fluid and pathological examination of lung tissue, we showed various morphological manifestations of this case, aiming at improving the morphological diagnosis level of laboratory physicians and enabling patients to be diagnosed and treated early