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Existing studies of coal self-ignition and impact frictional sparks do not provide valid support for the analysis of ignition sources in all cases of methane explosions in the gob. In this paper, the explosion in the gob of the Renlou coal mine is used to investigate the piezoelectric effect and ignition characteristics of roof collapse in identifying a new ignition source of gas explosion. Experimental and theoretical analyses conclude that the piezoelectric effect is produced by quartz, which is the main constituent of the roof sandstone. During the loading process, the piezoelectric effect and compressive strength are key factors in the gathering of free charges on rock tips. During rupture, the rock tip retains a large number of charges, forming a ″point-surface″ effect, which triggers an electron avalanche accompanied by an orange-yellow spark lasting over 22 ms, far exceeding the ionization energy and ignition induction period of methane–air mixtures. The piezoelectric effect and compressive strength of the rock cause the generation of electrical sparks, which is the ignition source of the explosion in the gob of Renlou mine II7322.

The quick and precise location of the burning zones of coal fires, which are continuously burning in abandoned coal mines worldwide, has long been a technical problem. The unmanned aerial vehicle (...

Anesthesia for upper limb surgery is commonly used in clinical practice. At present, the traditional method uses anatomical localization for nerve block, which can result incomplete local block and reduced anesthetic effect. Instead, ultrasound-guided nerve block can help clinicians intuitively grasp structure of patient tissues and provide a real-time display of needle penetration. Propofol is the most commonly used intravenous anesthetic in the world, but its use is still limited. In order to improve the limitations of this drug, a propofol nanoemulsion was developed and used in combination with a lower brachial plexus block. In this study, 100 patients were randomly divided into two groups, 50 in each group. The propofol nanoinjection for nerve block was used in the experimental group and ketamine was used in the control group. The quality of the operation, respiratory inhibition/asphyxia, recovery time, OPS score, agitation score, and complications were compared between the two groups. There was no significant difference in blood loss between the two groups (P > 0 05). The experimental results showed that the lower brachial plexus block and propofol nanoemulsion provided a better analgesic effect than ketamine and propofol nanoemulsion in the operation.

To investigate the overpressure of methane-air explosions in straight large-scale tunnels, the computational fluid dynamics (CFD) code of Flame Accelerator Simulator (FLACS) was used and validated against experiments conducted at three different scales, and the effects of the volume concentration of methane in air, the blockage ratio (BR), the tunnel length, and the cross-section were studied. When analysed using the GaussAmp mathematical model, the maximum peak overpressure appears at a volume concentration of 10.30 % of methane in air. Blockage ratios (BR) of 0.15 and 0.3 resulted in the combustion of methane-air mixtures with the volume concentration of 6.5 % and 14.0 % of methane in air, producing a fatal overpressure of 21 kPa. When the BR increases up to 0.75, both the lean and rich mixtures cause a peak overpressure of over 60 kPa. Combustion of the same methane-air mixture produces the same overpressure, which decays approximately linearly at the same slope owing to a smooth wall roughness before travelling near the outlet, independent of the specific tunnel length. A method to characterise the cross-sections was proposed, and the maximum peak overpressure of different lengths of methane-air mixtures in different cross-sectional tunnels was found, presenting various regimes from a hump shape to a wave-like uplift and bowl shape. The cross-section parameters determine the degree of confinement and further control the maximum peak overpressure in the modelled tunnels. An exponential asymptotic model can be used to conveniently obtain the maximum peak overpressure. These phenomena indicate that approximately square-shaped cross-sections should be selected to avoid an extremely high overpressure in large-scale tunnels with the potentially significant accumulation of methane-air mixtures.

To reveal the influence of pore structure of coal on the characteristics of coal dust generation during roadheader cutting, a self-developed coal cutting system was used to generate dust. A low field nuclear magnetic resonance was utilized to measure the pore system of coal. Results show that the porosity had negative correlations with the cumulative proportions of both respirable dust and fine particulate matter (PM2.5), but the positive influence on the mass ratio of dust generation (MRD) of total dust and slight effect on MRD of respirable dust and PM2.5 were observed. The correlations of the fractal dimension (Df) of pore structure on dust generation were inverse compared with that of porosity. The negative relationship between porosity and Df was the reason for the opposite correlations. This study can provide basic support for the estimate of dust hazard and the development of dust control technologies.

Gas explosion is one of the most deadly hazards in underground coal mining. Risk assessment has played an effective role in avoiding gas explosions and revising coal mine regulations. However, the traditional methods are deficient in quantitative evaluation, dynamic control and dealing with uncertainty. In this paper, a method of quantitative assessment the risk of gas explosion in underground coal mine using Bayesian network was proposed. A fuzzy analytic hierarchy process (FAHP) method based on subjective and objective information of experts was developed in the process of fuzzification. Through the Bayesian inference, the probability of occurrence of potential risk events and the probability distribution of risk factors can be calculated in real time according to on prior knowledge and evidence updating. Meanwhile, the most likely potential causes of accidents can be determined. A sensitivity analysis technique was utilized to investigate the contribution rate of each risk factor to a risk event, so as to determine the most critical risk factor. Taking Babao Coal Mine in China as the case, this study conducted a gas explosion risk assessment. The results show that the mothed of fuzzy AHP and Bayesian Network is feasible and applicable. It can be used as a decision-making tool to prevent coal mine gas explosions and provide decision makers with a technical guide for managing the coal mine gas explosion risk.

As dust is one of the main hazards generated by coal cutting, understanding the properties of dust generation is essential for preventing and controlling its propagation. This paper therefore aims to investigate the influence of coal brittleness on dust generation. A system was devised to produce dust and the density, uniaxial compressive strength, and Brazilian tensile strength of dust samples were then measured. The results showed that the cumulative proportions of fine particulate matter and respirable dust increased with brittleness, while a declining trend was observed from the mass ratio of total dust to coal sample. B14 (half of the product of compressive and tensile strength) had the strongest correlation with the properties of dust generation, and accounted for more than 95% of B15 (half of the sum of compressive and tensile strength).

Highlights • Pyroptosis genes were differentially expressed between HNSCC and normal tissue. • Developed a model for prognostic prediction of HNSCC based on pyroptosis genes. • The risk-score model was proved to be promising and reliable in practical patients., We aimed at establishing a risk – score model using pyroptosis-related genes to predict the prognosis of patients with head and neck squamous cell carcinoma (HNSCC). A total of 33 pyroptosis-related genes were selected. We then evaluated the data of 502 HNSCC patients and 44 normal patients from TCGA database. Gene expression was then profiled to detect differentially expressed genes (DEGs). Using the univariate, the least absolute shrinkage and selection operator (LASSO) Cox regression analyses, we generated a risk – score model. Tissue samples from neoplastic and normal sites of 44 HNSCC patients were collected. qRT-PCR were employed to analyze the mRNA level of the samples. Kaplan-Meier method was used to evaluate the overall survival rate (OS). Enrichment analysis was performed to elucidate the underlying mechanism of HNSCC patient's differentially survival status from the perspective of tumor immunology. 17 genes were categorized as DEGs. GSDME, IL-6, CASP8, CASP6, NLRP1 and NLRP6 were used to establish the risk – score model. Each patient's risk score in the TCGA cohort was calculated using the risk – score formula. The risk score was able to independently predict the OS of the HNSCC patients (P = 0.02). The OS analysis showed that the risk score model (P < 0.0001) was more reliable than single gene, a phenomenon verified by practical patient cohort. Additionally, enrichment analysis indicated more active immune activities in low-risk group than high-risk group. In conclusion, our risk – score model has provided novel strategy for the prediction of HNSCC patients’ prognosis.

The magnetic resonance imaging (MRI)-Linac system combines a MRI scanner and a linear accelerator (Linac) to realize real-time localization and adaptive radiotherapy for tumors. Given that the Australian MRI-Linac system has a 30-cm diameter of spherical volume (DSV) with a shimmed homogeneity of ±4.05 parts per million (ppm), a gradient nonlinearity (GNL) of5% can only be assured within 15 cm from the system's isocenter. GNL increases from the isocenter and escalates close to and outside of the edge of the DSV. Gradient nonlinearity can cause large geometric distortions, which may provide inaccurate tumor localization and potentially degrade the radiotherapy treatment. In this study, we aimed to characterize and correct the geometric distortions both inside and outside of the DSV.On the basis of phantom measurements, an inverse electromagnetic (EM) method was developed to reconstitute the virtual current density distribution that could generate gradient fields. The obtained virtual EM source was capable of characterizing the GNL field both inside and outside of the DSV. With the use of this GNL field information, our recently developed "GNL-encoding" reconstruction method was applied to correct the distortions implemented in the k-space domain.Both phantom and in vivo human images were used to validate the proposed method. The results showed that the maximal displacements within an imaging volume of 30 cm × 30 cm × 30 cm after using the fifth-order spherical harmonic (SH) method and the proposed method were 6.1 ± 0.6 mm and 1.8 ± 0.6 mm, respectively. Compared with the fifth-order SH-based method, the new solution decreased the percentage of markers (within an imaging volume of 30 cm × 30 cm × 30 cm) with ≥1.5-mm distortions from 6.3% to 1.3%, indicating substantially improved geometric accuracy.The experimental results indicated that the proposed method could provide substantially improved geometric accuracy for the region outside of the DSV, when comparing with the fifth-order SH-based method.

A fully integrated area efficient digital control circuit based on the ISO/IEC 15693 protocol is proposed for high frequency RFID tag chip. The proposed circuit is mainly composed of pulse position modulation decoder, Manchester encoder, anticonllision, low power circuit and other control logic. It supports six different data rates, namely, low or high data rate with one subcarrier (6.62 or 26.48 Kbit/s), low or high data rate with two subcarriers (6.67 or 26.69 Kbit/s), fast data rate with one subcarrier (13.24 or 52.97 Kbit/s). The proposed digital control circuit was integrated in an RFID tag IC and was fabricated using a 0.18-µm 2P6M CMOS process with an area of 306µm by 326µm which is smaller than the existing designs. Besides of small area, the circuit has an advantage of low power with a power consumption of less than 50µW.

To investigate the characteristics of coal dust generation when cut by a roadheader, a system was designed for performing cutting experiments. The aerodynamic diameter distribution of dust was tested by a laser particle size analyzer. Correlations between the coal proximate compositions and the characteristics of dust generation were studied. Results showed that fixed carbon had significantly positive correlations with the cumulative proportion of respirable dust and the rate of dust generation. The bonded high-density pulverized core could be responsible for reducing the correlation with fine particulate matter. The presence of moisture had inhibitory effects on dust generation. Volatile matter had a slightly negative influence on dust generation, and ash was considered to have no effect. More attention should be focused on heading faces with high fixed carbon and low moisture. This study provides essential guidance for understanding the characteristics of dust generation and improving dust reduction technologies.

Purpose The purpose of this study was to evaluate the management, outcomes, and technical and clinical safety of coil-assisted dominant outflow vein (DOV) occlusion for the ethanol embolization of high-flow arteriovenous malformations (AVMs) in the hands. Materials and Methods Between March 2013 and October 2016, 12 consecutive patients with AVMs with DOVs underwent ethanol embolization combined with detachable and pushable coil-assisted DOV occlusion. All patients completed the course of clinical follow-up (range: 14–57 months; mean: 36.7 months), and imaging follow-up (range: 8–25 months; mean: 16.6 months) results from the final treatment session were available for 8 patients. The therapeutic effects, degree of devascularization, and complications at the time of follow-up arteriography were evaluated as the clinical outcomes. Results The patients underwent 23 ethanol embolization procedures (range: 1–3; mean, 1.9) with 24 detachable coils and 223 pushable coils. The average stretched length of the total coils per patient was 320.17 cm. Seven of 12 patients (58.3%) exhibited complete responses, and 5 patients (41.7%) exhibited partial responses. Minor complications, including blistering and focal swelling, occurred in all 12 patients (100%) but showed spontaneous and complete recovery. No major complications occurred. Conclusions Ethanol embolization has the potential to control high-flow hand AVMs by using coil-assisted DOV occlusion with an acceptable risk of minor and major complications.

The types of ignition sources in coal mines have complicated diversity and susceptibility due to the environmental complexity in the coal mine production process. To determine the actual ignition cause of a potential accident scene and prevent the occurrence of gas explosions, this work provides a new risk analysis method for mine ignition source based on the fuzzy Bayesian network (FBN). The first step relates to risk factor analysis and the BN model establishment. In light of the expert group decision-making method, risk topological structural models of ignition sources are constructed. The second step is fuzzification and defuzzification. To ensure the reliability of data in the process of expert investigation, this study proposes to calculate the weights of experts using a fuzzy analytic hierarchy process (FAHP) method based on subjective and objective expert weights. The last step uses causal reasoning, logical reasoning and sensitivity analysis to calculate the probability of occurrence of potential risk events and the probability distribution of risk factors. Through the case study of Babao Coal Mine in China, it is demonstrated that the FBN simulation provides a feasible method for accurately identifying the cause of gas explosion ignition. The proposed model can be used by analysts and decision-makers in the coal mine as a decision support tool to increase the probability of the ignition source in complex environments.

Coalfield fire area reburning is one of the serious disasters in fire prevention and safety production. In this study, a synchronous thermal analyzer was used to conduct isothermal pyrolysis of jet coal at different temperatures, and the reaction characteristic parameters of different pyrolysis residual structures were analyzed. FTIR was used to measure group contents in raw coal and different pyrolysis residues. Programmed oxidation thermogravimetric experiments were carried out on the residues to obtain their oxidation characteristic parameters. The results demonstrated that the reaction characteristic parameters of the residual structures changed at 450 °C. The pyrolysis reaction mainly affected the variation of hydroxyl, aliphatic hydrocarbon, and aromatic hydrocarbon groups. The increase in pyrolysis temperature resulted in the decline in hydroxyl and aliphatic hydrocarbon groups as well as the increase in the aromatic hydrocarbon group. After pyrolysis, the ignition point temperature of the coal sample decreased, which causes the coal more likely to spontaneously ignite. It indicated that the pyrolysis residue at 450 °C is most likely to reburn. Compared with raw coal, the maximum combustion intensity of the pyrolysis residue was greatly increased, which reached the peak at 500 °C.

Hypoxia/reoxygenation (H/R) induced injury results in extensive damages to myocardial tissue in patients with coronary heart disease, which leads to heart failure. MicroRNA (miRNA) is thought to be associated with myocardial H/R injury. The purpose of this study was to investigate the in vitro role of microRNA-520d-3p in human myocardial cell (HCM) myocardial H/R injury. MTT method and Annexin V-FITC flow cytometry were employed to measure the viability and apoptosis of H/R treated HCM. RT-qPCR was employed to determine miRNA and mRNA expression. MicroRNA-520d-3p mimic and microRNA-520d-3p inhibitor were used to overexpression and inhibit the expression of microRNA-520d-3p. In addition, pcDNA3.1-ATG12 was used to upregulate ATG12 expression. The protein levels of ATG12, Bcl-2 and autophagy related-genes were determined by western blotting. Hypoxia/reoxygenation (H/R) injury could inhibit cell viability, apoptosis and inhibited microRNA-520d-3p expression in HCM. The down-regulation of microRNA-520d-3p inhibited cell viability and induced apoptosis in HCM. The overexpression of microRNA-520d-3p attenuated the effects of H/R treatment on the viability and apoptosis of HCM cells. In addition, microRNA-520d-3p inhibited the expression of autophagy-associated 12 (ATG12). More importantly, H/R treatment could promote autophagy in HCM, and microRNA-520d-3p mimic transfection could significantly reverse this effect. Our result indicated that overexpression of microRNA-520d-3p attenuated the effect of H/R treatments on cell viability, apoptosis and autophagy, through partly regulating ATG12 expression in HCM.

Background: This study aimed to explore the possible role and mechanism of venous hypertension (VH) in the occurrence and development of arteriovenous malformations (AVMs) and to study the therapeutic effect of VH regulation on AVMs to provide insight into AVM pathogenesis and explore new treatments.Methods: Maxillofacial VH models were established by cervical vascular anastomosis. Osteogenesis and angiogenesis in the model rats were analysed by imaging and histology, and the inhibitory effects of intraperitoneal (ip) sirolimus injection on angiogenesis were detected. The effect of sirolimus on the biological behaviour of human umbilical vein endothelial cells (HUVECs) cultured in vitro and mechanism of sirolimus were detected by cytology.Result: The local microvessel density increased, the vessels showed tortuous dilation, and mRNA and protein levels of angiogenesis-related genes were increased in venous hypertension environment. These phenomena were alleviated or eliminated by ip injection of a sirolimus solution. Sirolimus inhibited proliferation, tubule formation, migration, invasion, angiogenesis-related gene transcription and translation, and phosphorylation of mammalian target of rapamycin (mTOR) and its downstream substrate proteins S6K1 and 4EBP1.Conclusions: Abnormal angiogenesis caused by VH is related to abnormal activation of the mTOR pathway, which is important in regulating local angiogenesis; sirolimus inhibited hypertension-induced excessive angiogenesis in vivo and in vitro through the mTOR signalling pathway. This study provides a basis for further mechanistic study of AVM formation and insight into sirolimus as a possible target drug for AVM management.

The inhibitory effects of two ionic liquids (ILs), ethyltributylphosphonium bromide ([P4,4,4,2]Br) and the hydroxyl functional 1-hydroxyethyl-3-methyl imidazolium tosylate ([Hemim]Tos), on spontaneous combustion of coal were investigated and compared. The changes in various active functional groups of coal under IL inhibition were measured by in situ FTIR and analysed semi-quantitatively. Additionally, the impact of the ILs on the heat release rate of coal oxidation was examined by a micro-calorimetric technique. Subsequently, kinetic calculations were employed to elucidate the changes in the intrinsic mechanism of coal oxidation in the presence of ILs. The results revealed that [P4,4,4,2]Br and [Hemim]Tos exhibited distinctive inhibition characteristics on spontaneous combustion of coal. [P4,4,4,2]Br significantly reduced the associative hydroxyl group of coal by destroying the hydrogen bonds and forming stable ether structures. This kind of IL manifested significant inhibition of heat release at the slow oxidation stage of spontaneous combustion of coal. On the other hand, the reductive [Hemim]Tos afforded hydrogen ions from the functionalised O H bonds to eliminate the reactivity of the peroxide radicals. This led to a reduction in the formation of C O double bond intermediates in the transition and rapid oxidation stages at higher temperatures.

Goaf fires are prevalent in underground coal mines and have drawn increasing public attention. Inhibition foam is recognized as an efficient means of fire extinguishment in a huge volume of porous material. A verisimilar goaf platform setup and a foam preparation system were developed. Experimental results show that increasing the gas/liquid ratio improves the foam stack effect. The optimum gas/liquid ratio and the ratio of infusion pipe length and cooling zone length are suggested for a practical application. The goaf interior pressure test indicates that the air leakage is controlled effectively by the inhibition foam. A perforated pipe will be superior to the standard one for a practical application due to its better diffusivity and lower infusion pressure.

Studying the effect of oxygen in coal oxidation is very important for understanding and controlling coal spontaneous combustion. However, the oxygen effect is not very easy to determine clearly due...

This paper proposes a novel jet-type foam generator of air self-suction intended for dust control in coal mines that overcome the shortcomings of conventional compressed air foam preparation devices. Three non-dimensional numbers of geometric parameters were obtained through theoretical analysis, namely distance–diameter ratio ( $$R_\mathrm{td})$$ , length–diameter ratio ( $$R_\mathrm{ld})$$ , and area ratio ( $$R_{\mathrm{m}})$$ . And various experiments were conducted to investigate the effects of the three important non-dimensional geometric parameters on air suction properties of the proposed foam generator. The results show that air suction capacity first increases and then decreases with the increasing of $$R_\mathrm{td}$$ and $$R_\mathrm{ld}$$ , and air–water ratio increases with the increasing of $$R_{\mathrm{m}}$$ . And the optimum distance–diameter ratio is identified to be 1/3–2/3, the optimum length–diameter ratio is approximately 20, and the optimum area ratio should be 81–144. This study provides a solid foundation for application of the proposed foam preparation technology.

Self-potential method has been used to detect coal fires for decades. However, the origin of self-potential anomaly relating to coal fires is still unclear. In this paper, we first analyze three possible sources of self-potential anomaly that relating to coal fires, i.e., the thermoelectric potential, the redox potential and the streaming potential, among which the streaming potential is negligible. Then, an experimental system is designed to research the above-mentioned three possible sources, in which six experiments are conducted finally. The results verify the existence of the thermoelectric potential and the redox potential. The self-potential that measured on the surface increases with the increase of temperature of the heat source, but decreases dramatically with the increase of its buried depth. Furthermore, the redox potential reduces the total self-potential values on the surface.

Water spray is the most commonly used method for suppressing mine dust. On the heading face of high gassy mine, forced ventilation is employed to dilute and discharge methane in order to prevent methane accumulation. In this paper, we utilize the program ANSYS FLUENT to investigate the influence of airflow from forced ventilation on the water spray flow field. The three-dimensional (3D) steady wind and spray flow models are successfully established and simulated under different spray pressures, which range from 0.5 MPa to 3.0 MPa. The results show that the wind wall produces a significant number of vortices from the interaction between the wind and heading face, which blocks the advance of the droplets. As spray pressure increases, the trajectory of the spray droplets is more strongly affected; i.e. the spray was so disturbed that it could not reach the dust source. The average droplet diameter gradually decreases, and the average droplet velocity first decreases and then increases as the spray pressure increases. Under the condition of this study, we find 2.4 MPa to be the optimal operating pressure for water spray to suppress dust at dust source on the coal wall, which can prevent dust from entering the mine air and effectively reduce the dust concentration.

As an explosion control measure, rock dusting has been used in underground coal mines in many major coal producing countries with different standards. The effectiveness of the rock dust in reducing explosion intensity has been proven by historic events and laboratory experiments. The main functions of rock dust in controlling mine explosions (i.e., isolator, physical heat sink and chemical energy absorber) have been quantitatively studied and results are presented in this paper.

To solve the drawbacks of the conventional foaming method used for dust suppression, a new foaming device is designed through integrating the foaming agent adding device and foam generator. Its performance is investigated experimentally under different working conditions. Testing results show that foaming agent is automatically added into the device at the working water flow of 0.84–1.12 m3/h and water pressure of 0.3–0.52 MPa. The reasonable compressed air flow is 45–48 m3/h, in which range the foam flow and expansion ratio both reach the maximum. The foaming device requires a minimum air pressure of 0.46 MPa to meet the outlet pressure demand. Field application proved that foam technology using the new foaming device made a marked dust suppression effect. The foam dust suppression efficiency was 87.1%–88.3%, much higher than that achieved by the roadheader water spraying. In addition, foam used less water that relieves the water supply burden in coal mines and improves the working environment. Based on the above contributions, it is believed that the proposed foaming device will greatly promote the large-scale application of foam technology used for suppressing dust in underground coal mines.

In this paper, a novel type of composite inhibitor (PAA/SA-CC) was developed and characterized with the aim of achieving sustained and highly effective inhibition on spontaneous combustion of low-rank coal. A concept of realizing the caged-wrapping and sustained-releasing function of polymer as regard to high-activity chemical inhibitor was proposed, basing on which the composite inhibitor was prepared with poly(acrylic acid)/sodium alginate super absorbent and (+)-catechin. Subsequently, synchronous thermal analysis was carried out to investigate the influence of inhibitors on the tendency of coal to spontaneous combustion, which was characterized by four characteristic temperatures and three other characteristic parameters marked. Furthermore, hot-surface ignition tests were conducted to validate the inhibition on coal ignition behavior. Finally, non-isothermal isoconversional methods were performed by Starink model and Friedman-Reich-Levi model, respectively. The results demonstrate that PAA/SA-CC synergizes the inhibiting characteristics of the two distinctive inhibitors, especially exerts a continuously high-efficiency inhibition on the coal-oxygen chemisorption, which performs better than the case of mechanically blending. Besides, both the two kinetic analysis approaches agree on the results that the incorporation of 3 wt.% PAA/SA-CC shifts the apparent activation energy-temperature evolution to higher levels.

Safe mining is the premise and guarantee of sustainable development of coal energy. Due to the combination of excellent properties of polymers and traditional soft matters, polymer-containing soft matters are playing an increasingly important role in mine disaster and hazard control. To summarize the valuable work in recent years and provide reference and inspiration for researchers in this field, this paper reviewed the recent research progress in polymer-containing soft matters with respect to mine dust control, mine fire control, mine gas control and mine roadway support. From the perspective role of polymers in a material system, we classify mine polymer-containing soft matters into two categories. The first is polymer additive materials, in which polymers are used as additives to modify fluid-like soft matters, such as dust-reducing agents (surfactant solution) and dust-suppressing foams. The second is polymer-based materials, in which polymers are used as a main component to form high performance solid-like soft matters, such as fire prevention gels, foam gels, gas hole sealing material and resin anchorage agent. The preparation principle, properties and application of these soft matters are comprehensively reviewed. Furthermore, future research directions are also suggested.

Intraosseous arteriovenous malformations in jaws (j-AVMs) are rare congenital high-flow vascular anomalies with a high tendency of life-threatening haemorrhage and are regarded as one of the most dangerous haemorrhagic diseases in maxillofacial region. Pre-treatment clinical and imaging evaluations serve as the most important diagnostic modalities. A retrospective study involved 211 patients with j-AVMs from November 2003 to November 2017 was performed. The male-to-female ratio of j-AVMs was approximately 4:3. The mean age of the patients with j-AVMs is 21.86. Bleeding was the main complaint associated with j-AVMs. J-AVMs occurred in the mandible more often than in the maxilla (64.93% and 32.23%, respectively). Most j-AVMs (95.26%) occurred in the posterior teeth region. Classical imaging features of j-AVMs included: an unclear maxillary sinus with a mild ground-glass appearance (maxillary j-AVMs) and a clear oval or irregular lucency that is mostly centred on the root of the first molar (mandibular j-AVMs) on OPGs, enhancement in the cancellous bone on contrast-enhanced CTs. Other atypical features of j-AVMs were also concluded. A comprehensive diagnose system based on clinical and imaging features of j-AVMs could provide valuable reference data for clinical management of j-AVMs and help avoid improper iatrogenic trauma or delayed treatment.

Objective Lingual arteriovenous malformations (AVMs) are extremely rare in clinical practice, which has limited comprehensive research to find standard treatment protocols. This study summarizes the clinical features of lingual AVMs and assesses the safety and efficacy of ethanol embolotherapy in the management of these lesions. Methods Our study group was composed of 52 patients with lingual AVMs treated by ethanol embolization, all of whom received general anesthesia. The optimal access to the nidus of the AVM was by direct puncture, transarterial catheterization, transvenous catheterization, and a combination of these routes. Pure ethanol was manually injected into the nidus of the AVMs. The observed major or minor complications related to ethanol embolization were analyzed, and periodic follow-up of the patients was performed. The devascularization of the lingual AVMs between baseline and final angiography and the clinical outcomes of symptoms and signs after ethanol embolization were evaluated. Results There were 171 embolization procedures (mean, 3.3; range, 1-20) including 166 ethanol embolizations performed; the average volume of ethanol injected in a single ethanol embolization session was 29.8 mL (range, 1-65 mL). Therapeutic outcomes were complete response in 17 patients (33%), partial response in 33 patients (63%), and no response in 2 patients (4%). The effective therapeutic outcomes were gained in 96% of the patients with lingual AVMs treated with ethanol embolization; 25 (48%) of the patients had 83 complications, which were necrosis, infection, hemorrhage of the puncture point, transient hemoglobinuria, postoperative irritability, airway constriction, and coil migration, occurring in 78 procedures (46%). Regular follow-up of all the patients was performed, with the average follow-up period of 37.9 months (range, 1-125 months) after the last treatment. Conclusions Ethanol embolization of lingual AVMs is safe and efficacious and is recommended to be the potential preferred method in the treatment of these complicated lesions.

Coal refuse pile fires are a serious health, safety, and environment hazard. The fires in Guoshan Coal Refuse Pile affect daily life of the local residents. Although conventional fire control methods (water injection, grouting and surface sealing) were used to control the fires, they rekindled soon after the fire-fighting engineering was quitted. Thus, effective methods need to be applied to extinguish the fires completely without reignition. In this paper, the environmental impact of the fire on the local land, water and air is illustrated by sample analysis and photos. The self-potential method, which achieves remote detection from the ground surface, is adopted to delineate the scope of the fires to give support for the efficient and economical extinguishment of them. The three-phase foam containing water, gas and loess is proposed to control and extinguish the fires. The corresponding fire-fighting system is also invented to fit the field work and put out the fires more efficiently and conveniently. The temperature monitoring result shows that the fires are extinguished successfully with no sign of reignition.

To further understand the problems of coal combustion and coalfield fire reignition, this paper researched the reaction characteristics of coal pyrolysis and low oxygen combustion and the reburning oxidation characteristics of residual structure by thermal analysis methods. The results show that temperature promotes both pyrolysis and low oxygen combustion reactions, but low oxygen combustion reaction is more sensitive to temperature changes. As the constant temperature rises, the mass reduction rate of low oxygen combustion of coal samples reaches 80% on average, which is 4 times that of pyrolysis, and the variations of thermogravimetric parameters are also significantly higher than those of pyrolysis. However, the higher the pyrolysis degree of the residues, the stronger their oxidizability, which greatly enhances the intensity and concentration of the secondary combustion, and the mass of residues is reduced by 90% on average. Conversely, because the combustible components are continuously consumed during low oxygen combustion, the reburning characteristics of residues become less obvious. For instance, the weight loss rate slows down, the burning becomes dispersed, and the burning intensity is weakened. In addition, the heat release is reduced from 8662 to 444.5 J/g, and the change trend is just opposite to that of pyrolysis. The above results show that as the constant temperature rises, the pyrolysis reaction greatly shortens the reburning process, while the low oxygen combustion reaction largely inhibits the reburning.

Electric effects are generated during the deformation and fracture of coal mine roof sandstones. Previous research has mostly focused on the mechanism of electric effect generation and the electromagnetic radiation released. However, few studies have investigated the hazard characteristics of the high-energy electrons released. This study explores the discharge and ignition characteristics of roof indentation fracture to identify the real ignition source of a gas explosion in a coal mine goaf. Theoretical and experimental analyses conclude that the charge of the coal mine roof sandstone will gradually escape from the surface during the loading process. The charge release process of the rock before fracture is related to the loading rate, and an instantaneous high voltage will be formed during fracture of the rock. The compressive strength of the rock plays a key role in this type of instantaneous discharge process. An electric spark can be generated at the moment of rock fracture under loading. The high-energy electrons released by rock deformation and rupture can ionise the air. Moreover, the electric spark can persist for more than 20 ms, which considerably exceeds the induction period for gas ignition. When the quartz content of the roof rock is high and reaches a certain compressive strength, stress mutations can cause the roof to undergo instantaneous rupture and generate electric sparks. The premixed gas air gathered in the area is thus broken down and ionised, igniting the gas and producing a gas explosion.

To investigate the characteristics of methane-air explosions in large-scale tunnels with different structures, the CFD code for gas explosion modelling of FLACS was validated and used to model the explosions in tunnelling faces, coalfaces and crosscuts, where explosions mostly occurred in coalmines. The maximum overpressures were obtained as about 150–1400 kPa but varied for places with different cross-sections. The confinement degree and combustible mixture volume compete for controlling the overpressures, the space congestion degree influences the competition. For the tunnelling faces and crosscuts with low congestions, the increase of confinement degree caused by reducing cross-sections takes the dominant effect, which makes the overpressure in 3 m × 2 m cross-section tunnels higher. However, the 6 m × 4 m coalface produces the largest overpressure as the highly congested coalface strengthens the effect of increasing the mixture volume on pressure rise. Since the pressure reflection results from space constraints, a higher confinement degree causes a greater reflection. In crosscuts with both ends closed, the delayed combustion of the unburnt rich mixture after the seal’s failure generates a high pressure than assumed. Because of containing the same volume combustible mixtures in the crosscut modelling with the same cross-section, little difference exists in the overpressure regardless of sealing conditions. The flame is more inclined to propagate towards free spaces, and the flame of a larger volume combustible mixture fills a longer tunnel more comprehensively. In straight tunnelling faces, the flame length can be calculated as the product of the equivalent side length of the cross-section and its corresponding simulated constant.

An experimental platform was built to investigate how aqueous foam extinguishes fire in the upper area of a goaf. A temperature-programmed oxidation testing method was used to illustrate the inhibitory effect of foam. The results showed that foam has good accumulation characteristics, cooling performance, blocking effect, and inhibition. Foam extinguishes the fire in the upper area of a goaf and cools the entire goaf from bottom to top; it even diffuses into the interior of the high-temperature zone and extinguishes any hidden fire in the porous medium. In addition, foam blocks all the cracks in the goaf, thus blocking the air supply and maintaining a constant negative pressure in the goaf. By restricting chemical reactions between coal and oxygen, foam increases the crossing point temperature and reduces CO generation and thus prevents the further oxidation of coal.

Composites of physical (superabsorbent hydrogel) and chemical (ascorbic acid) inhibitors were investigated to ascertain their ability to prevent the spontaneous combustion of coal. CO emissions from the oxidation of the composite inhibitor-treated coal were markedly lower than those for tests with raw coal. Less oxygen was also consumed during low-temperature oxidation, while the crossing point temperature of the inhibitor-treated coals was higher than that of raw coal. Together, these results demonstrate that the composite inhibitors can effectively mitigate coal oxidation. However, variation in the effectiveness was observed depending on the inhibitor-loading and the blend of the individual inhibitors in the composite. The composite inhibitor was shown to more effectively prevent oxidation than use of an individual inhibitor. The network structure of the composite inhibitor, revealed by SEM analysis, was suggested to explain the suppression of the coal oxidation.

The built-in Electro-Static discharge (ESD) protection circuits for Radio frequency identification (RFID) tag ICs are proposed. The ESD protection function is built into the rectifier and amplitude limiter. The rectifier and limiter are connected directly to the RF interface, and some transistors can discharge the larger current. These transistors can be used to build ESD protection circuits, through the redesign and optimization. The built-in ESD protection circuits can improve the ESD protection level and reduce the layout area. The circuits have been fabricated in 0.18μm CMOS process. The test results show that the built-in ESD protection circuits work well under 4kV ESD pressure and save as much as 72% of the layout area compare with foundry standard ESD protection cells.

A sustained release type of inhibitor (PS-C) prepared with poly(acrylic acid)/sodium alginate super absorbent (PS), ascorbic acid (VC), and water was developed, which exhibited a not only highly efficient but also sustained inhibition performance on the spontaneous combustion of coal. The impact of PS hydrogel on coal oxidation was examined thermodynamically by TGA–DSC tests, and the variations of functional groups on coal surface under the influence of VC were in situ monitored by an FT-IR technique. The inhibition performance was evaluated with a parameter defined as the emitted carbon monoxide concentration decay rate during coal oxidation. The results show that the PS hydrogel and VC perform distinctive inhibition characteristics by physically removing the accumulated heat and chemically interrupting the free radical chain reaction of coal oxidation, respectively. The composite PS-C is capable of combining the inhibition characteristics of PS hydrogel and VC as well as further realizing a dramatic syn...

Foam technology utilizes the good coverage of foam to form a closed space around dust sources. The foam then wets the dust particles, causing them to adhere before they spread into the air, resulting in better dust control than with water sprays. In the process of foam dust control at a heading face, the foam spray trajectory is highly influenced by the wind, making it difficult to focus foam on the dust sources, which wastes the foam and reduces dust control efficiency. To resolve this problem, the idea of transporting foam to the cutting head through the roadheader’s inner pipeline is proposed. To adapt to the high resistance of foam delivery in the roadheader’s inner pipeline, according to the water and air supply of the heading face, a table water-jet suction device and porous spiral coupling foaming device were designed, and the working conditions were tested using a self-designed experiment system in the laboratory. The results showed that the foaming agent could be automatically added into the device at a working water flow rate of 1–1.6 m3/h at a ratio of 1%. The optimum air flow was 45–50 m3/h, in which range the foam expansion ratio reached the maximum and the outlet pressure demand was satisfied. Field application showed that the new foam method had a better dust control efficiencies than traditional foam methods.

Here a new automated and inexpensive atomic simulation approach including sequential oxygen diffusion and simplified reaction was created to explore the char reactivity and combustion behavior during oxy-fuel combustion. Two large-scale (>40,000 carbon atoms) coal chars (higher- and lower-porosity chars) that differ primarily in pore volume and pore size distribution were evaluated against graphite with similar number of carbon atoms. The structural transformations, total atoms, reactive atoms, their location, conversion, rate (number of atoms reacting), size of the char, and apparent density were captured. Post analysis evaluated the total porosity, micro/mesoporosity volume, and atomic surface area. The higher porosity char burn-off was ∼38% more rapid than the graphite (number of steps), similar to the lower porosity char (∼33% faster). The peak reactivity followed the maximum atomic surface area (with a delay of 5–10% conversion) than decreased—as there were fewer reactive carbons. Porosity volume increases with conversion until 50–70% where the porosity declines. For both chars the microporosity contribution increased until 30–35% conversion then the pores either grow or coalesce into the mesoporous classification. The chars burning modes are initially changing density (pore growth accompany mass loss) until ∼50% conversion when the mode became a combination of changing density and shrinking core. Graphite was less reactive and followed a shrinking core consistent with the simulation restrictions. This approach is likely to aid in the exploration of the influence of char structure and conversion conditions upon reactivity and char behavior in combustion and gasification.

Background The purpose of this study was to evaluate the safety and efficacy of direct intralesional ethanol sclerotherapy for venous malformations (VMs) with oropharyngeal involvement after a temporary tracheotomy. Methods A retrospective assessment was carried out to evaluate the efficacy of direct intralesional ethanol sclerotherapy on 21 consecutive patients presenting with extensive VMs involving the oropharynx in the head and neck and who had undergone tracheotomy. Results Of the 21 patients, 4 were treated once and 17 were treated from 2 to 5 times. The duration of follow-up was, on average, 9.1 months. Of the 21 patients, 7 (33.3%) had complete palliation, whereas the rest (66.7%) achieved partial palliation. Minor complications occurred in 12 of the 21 patients. Conclusion Direct intralesional ethanol sclerotherapy after a temporary tracheotomy is a safe and effective treatment for extensive VMs involving oropharyngeal areas of the head and neck. © 2016 Wiley Periodicals, Inc. Head Neck, 2016

Mining-induced voids are a necessary factor triggering underground coal fires that endanger the underground and atmospheric environment. On the other hand, voids provide channels for underground fluid and fire-fighting material migration. A series of void rate models were proposed to determine the three-dimensional heterogeneous distribution of the mining-induced voids in the disturbed strata. The void rate distribution map of horizontal voids presents a reversed “quadripod-type” shape in the strata plane, the void rate of vertical voids has a shape similar to two “basins” of different sizes and contrasting opening directions nested together, and the void rate of isotropic pores presents a “basin-type”. It can be deduced from the distribution maps that were calculated by theoretical and numerical models that the voids present a “fractured dome” distribution and that the void rate gradually decreases from foot to crown of the dome. It was ascertained from the application of void rate models in the hydro-thermal investigation of an underground coal fire that the correlation between heat production and ground surface temperature presents a linear function, while that between outflow velocity and fire source temperature has a negative-exponential-power relationship. Additionally, a new Plan-Do-Check-Adjust cycle was established for the management of fire-fighting engineering, which includes the delineation of fire zones, the evaluation of fire behavior, the optimization of fire-fighting measures, the performance of the fire-fighting plan, and the assessment of control results to determine whether the fire-fighting plan should be reformulated or improved. After five control cycles lasting nine months, an approximately 115,200 m 2 fire zone was controlled.

Simultaneous thermal analysis was used to study the influence of Vitamin C as possible chemical additive inhibiting coal oxidation process at low temperature. Some oxidation characteristics of Vitamin C affecting the coal oxidation were investigated at different heating rates. The TG-DSC data show that the impact of Vitamin C on coal oxidation process can be directly evaluated using ignition temperature and critical temperature. Comparison with the effect of water on coal oxidation shows that Vitamin C is more efficient than water. However, the blank experiment conducted with inert α-Al2O3 also suggests that Vitamin C can decompose at about 200 °C, which limits the usage of Vitamin C on inhibiting coal oxidation.

This paper deals with the permanent magnet synchronous motor (PMSM) speed estimation and parameters identification problems. It proposes a solution to estimate speed and identify stator resistance, d-axis and q-axis inductance simultaneously. In fact, there are a lot of methods for estimating the speed, for example high-frequency injection, Kalman filter, and model reference adaptive system (MRAS). However, with the PMSM running, some parameters will change such as the stator resistance will change with the increase in temperature. These parameters are useful for estimating the speed. So, it is necessary to identify parameters simultaneously to adapt to the changes of these parameters. In this paper, MRAS is the theoretical basis. First, the adaptive law of speed observer is constructed through Popov stability. Then, the adaptive laws of stator resistance, d-axis, and q-axis inductance are constructed through Lyapunov stability. The stability of the proposed observers is also discussed. Last, this paper uses field-oriented control strategy and illustrates the obtained results through simulation and experiment.

Coal can maintain smoldering combustion for a long time in the gob (mined-out) area which is a serious threat to the safety mining of a coal mine. However, few literatures can be obtained to well understand the smoldering phenomena of coal. To obtain the coal smoldering characteristics, vertical forward and reverse smoldering tests under different air flow rate were performed, and the smoldering combustion process, speed, and temperature were analyzed. It is found that although the combustion process of forward and reverse smoldering is significantly different, their smoldering speeds are the same and both increase monotonically with air flow rate as the higher the air flow rate is, the greater the oxygen consumption rate can reach. Even when the air flow rate is 0.074 m/min in that the wind speed belongs to the suffocation zone of the gob, the coal can still undergo smoldering until complete combustion. This indicates that the smoldering fire cannot be effectively extinguished by only accelerating the stoping speed of the working face to create fire in the suffocation zone during the mining process. And for a sealed fire zone, it is also difficult for the smoldering fire to be completely extinguished as the fire zone cannot be absolutely sealed. Meanwhile, the risk of reverse smoldering is greater than forward smoldering due to its larger smoldering temperature.

To overcome the drawbacks of the conventional foam technology used for dust suppression, including large pressure loss, high water pressure and low driving pressure, a new pneumatic foaming system is introduced. Then an original design of foaming agent mixing device is proposed, and its performance is investigated and evaluated under different pressure compensations. Experimental results show that the maximum absorption amount increases by 2.9–6.7 times at a pressure compensation of 0.04–0.2 MPa compared with no pressure compensation. The pressure loss and pressure fluctuation both reduce significantly with increasing pressure compensation. The critical outlet pressure increases by 30.4–240%. Field application indicates that the proposed mixing device ensures the reliable addition of foaming agent used for foam dust suppression. The effect of foam on dust suppression is remarkable, and the economic cost of foam is low. Therefore, there is reason to believe that the new mixing device will greatly promote foam technology to be widely used for suppressing dust in underground coal mines. Keywords: Compressed air, Jet, Pressure compensation, Foam, Dust suppression

In order to improve the utilization rate of foam, an arc jet nozzle was designed for precise dust control. Through theoretical analysis, the different demands of foam were compared amongst arc jets, flat jets and full cone jets when the dust source was covered identically by foam. It is proved that foam consumption was least when an arc jet was used. Foam production capability of an arc jet nozzle under different conditions was investigated through experiments. The results show that with the gas liquid ratio (GLR) increasing, the spray state of an arc jet nozzle presents successively water jet, foam jet and mist. Under a reasonable working condition range of foam production and a fixed GLR, foam production quantity increases at first, and then decreases with the increase of liquid supply quantity. When the inner diameter of the nozzle is 14 mm, the best GLR is 30 and the optimum liquid supply quantity is 0.375 m3/h. The results of field experiments show that the total dust and respirable dust suppression efficiency of arc jet nozzles is 85.8% and 82.6% respectively, which are 1.39 and 1.37 times higher than the full cone nozzles and 1.20 and 1.19 times higher than the flat nozzles. Keywords: Dust control, Precise spray, Arc jet, Gas liquid ratio (GLR), Dust suppression efficiency

To mitigate the effect of the distributed generation (DG) connection on the voltage profile and power loss, the DG optimal configuration and network reconfiguration are used in distribution automation. In this paper, a new optimization method named Archimedes Optimization Algorithm (AOA) is proposed, unifying the DG optimal configuration and network reconfiguration. The DG locations and capacities are coded by integral and real numbers simultaneously in the proposed method. The integer mesh-network coding method is integrated into the new method to solve the network reconfiguration problem. The new method is compared with the Improved Genetic Algorithm (IGA) as well as the Particle Swarm Optimization (PSO). Results demonstrate that the proposed method has advantages in improving the voltage profile and reducing the power loss.

Inert gases can effectively inhibit coal spontaneous combustion. In this paper, the inhibition effect of inert gases (N2 and CO2) on coal spontaneous combustion was studied. In the low-temperature oxidation stage, the constant-temperature heat release and apparent activation energy of coal sample were measured and calculated by the C80 micro-calorimeter. In the high-temperature combustion stage, the critical temperature, maximum peak temperature, ignition temperature, and burn-out temperature of coal samples were analyzed by the synchronous thermal analyzer. The results demonstrate that with the decrease of O2 concentration, the oxidation heat release of coal samples drops gradually while the apparent activation energy increases gradually. In the N2 and CO2 atmospheres, as the O2 concentration is reduced to 1.5% and 3%, respectively, the value of apparent activation energy changes from negative to positive, and the spontaneous reaction transits to a nonspontaneous reaction. The TG-DTG (thermogravimetric-derivative thermogravimetric) curve of coal sample in the high-temperature combustion stage indicates that the critical temperature exhibits a W-shaped trend with the decrease of O2 concentration, which also leads to gradual increases of maximum peak temperature, ignition temperature, and burn-out temperature. The above results signify that increasing the inert gas concentration can gradually reduce the oxidation and combustion rate and improve the inhibition effect on coal spontaneous combustion. In addition, when the O2 concentration is the same, the inhibition effect of CO2 on coal spontaneous combustion is superior to that of N2.