Experimental Study on Carbon Dioxide Displacement by Coal Seam Water Injection.

Using water to displace carbon dioxide adsorbed in coal can prevent coal and gas outbursts. However, the mechanism of continuous water injection replacing adsorbed gases in coal has not been well studied. An experiment with the same water injection pressure and different adsorption equilibrium pressures for displacing carbon dioxide was conducted. The variation patterns of the amount of displaced carbon dioxide, time, and water displacement rate, displacement ratio, and water action ratio were analyzed. The modes of water injection displacing carbon dioxide are discussed. The results show that the change in the amount of displaced carbon dioxide consists of three stages: rapid, slow, and stop growth stages. For the same displacement time, as the adsorption equilibrium pressure rises, more carbon dioxide is displaced. The time displacement rate and water displacement rate can be divided into three stages: rising, peak, and dropping stages. As the adsorption equilibrium pressure increases, the duration of the peak stage decreases, while the time and water displacement rates increase. At different adsorption equilibrium pressures, the carbon dioxide displacement ratio ranged from 45% to 54%, less than the natural desorption ratio. But the water action ratio containing the gas dissolution amount was close to or greater than the natural desorption ratio. Thus, the displacement effect of flowing water accelerated the desorption of carbon dioxide in coal. The modes of carbon dioxide displacement by water injection include water-displacement, gas-dissolution displacement, and gas-diffusion-dissolution displacement. The findings of this study provide novel suggestions for preventing and controlling coal and gas outbursts.

Experimental study on the gas desorption law in coal affected by dynamic water injection.

Water from hydraulic technology affects the desorption of gas from coal seams. Gas desorption behavior is critical information for gas control in coal mines. In this study, a designed coal seam water injection simulation experimental device was utilized to conduct dynamic water injection experiments on coal samples at different adsorption equilibrium pressures, analyzing the gas desorption law under dynamic water injection, as well as the role of water replacement, water imbibition and water blockage in gas desorption. The results showed that water altered the gas desorption rate in coal, causing fluctuating attenuation of the desorption rate of a water-injected coal sample (WCS). Under the same adsorption equilibrium pressure, the relationship between the desorption rate of the WCS and the non-water-injected coal samples (NCS) underwent a transition in desorption time. In contrast to the NCS desorption curves, the WCS desorption curves lacked a rapid growth phase and exhibited only a slow growth phase and a stopping phase. Water imbibition and water replacement promoted the desorption of gas in the non-wet area during the water injection process, while it inhibited the desorption of gas in the wet area. Under the effects of water imbibition, water blockage, and water replacement, the discharge rate of WCS is greater than the desorption rate of NCS, indicating that water injection increases the total amount of gas desorption. The study results have significant implications for gas extraction and the prevention and control of coal and gas outbursts.

Research on charge induction law and application of coal samples with different fissures.

Indoor testing are performed to explore the charge induction law during the uniaxial compression fracture process of coal samples, and the charge time and frequency domain signals of coal samples with different primary fissures are analyzed in the paper. On-site monitoring of charge in different fissures distribution areas of underground coal tunnels, and the charge signals of different drillingdepths in coal seams are analyzed. The results show that the uniaxial compressive strength and elastic modulus of multi-fissured coal samples are less than those of less fissured coal samples, and the Poisson's ratio is greater than those of less fissured coal samples. The charge induction signal intensity during the fracture process of multi-fissured coal samples is relatively low, but it is concentrated at the low frequency of 0-50 Hz in the compacting elasticity stage. The charge signal intensity during the fracture process of coal samples with less fissure is relatively high, and the charge frequency during the reinforcement damage stage is concentrated at a low frequency of 0-50 Hz. Therefore, the sudden appearance of low-frequency charge signals is more suitable as effective precursor information for the instability and failure of less fissured coal bodies. The average charge intensity is small in the multi-fissured area with a drilling depth of 1-4 m in the coal seam, and the average charge intensity of the coal body with less fissures is larger in the 5-12 m region. The on-site charge monitoring results have good consistency with the indoor test results. This study has guiding significance in setting up a charge monitoring warning index of instability failure in different coal body fissures regions.

Research on application of helmet wearing detection improved by YOLOv4 algorithm.

Aiming at the problem that the model of YOLOv4 algorithm has too many parameters and the detection effect of small targets is poor, this paper proposes an improved helmet fitting detection model based on YOLOv4 algorithm. Firstly, this model improves the detection accuracy of small targets by adding multi-scale prediction and improving the structure of PANet network. Then, the improved depth-separable convolution was used to replace the standard 3 × 3 convolution, which greatly reduced the model parameters without reducing the detection ability of the model. Finally, the k_means clustering algorithm is used to optimize the prior box. The model was tested on the self-made helmet dataset helmet_dataset. Experimental results show that compared with the safety helmet detection model based on Faster RCNN algorithm, the improved YOLOv4 algorithm has faster detection speed, higher detection accuracy and smaller number of model parameters. Compared with the original YOLOv4 model, the mAP of the improved YOLOv4 algorithm is increased by 0.49%, reaching 93.05%. The number of model parameters was reduced by about 58%, to about 105 MB. The model reasoning speed is 35 FPS. The improved YOLOv4 algorithm can meet the requirements of helmet wearing detection in multiple scenarios.

Research on Simultaneous localization and mapping Algorithm based on Lidar and IMU.

In recent years, the research of autonomous driving and mobile robot technology is a hot research direction. The ability of simultaneous positioning and mapping is an important prerequisite for unmanned systems. Lidar is widely used as the main sensor in SLAM (Simultaneous Localization and Mapping) technology because of its high precision and all-weather operation. The combination of Lidar and IMU (Inertial Measurement Unit) is an effective method to improve overall accuracy. In this paper, multi-line Lidar is used as the main data acquisition sensor, and the data provided by IMU is integrated to study robot positioning and environment modeling. On the one hand, this paper proposes an optimization method of tight coupling of lidar and IMU using factor mapping to optimize the mapping effect. Use the sliding window to limit the number of frames optimized in the factor graph. The edge method is used to ensure that the optimization accuracy is not reduced. The results show that the point plane matching mapping method based on factor graph optimization has a better mapping effect and smaller error. After using sliding window optimization, the speed is improved, which is an important basis for the realization of unmanned systems. On the other hand, on the basis of improving the method of optimizing the mapping using factor mapping, the scanning context loopback detection method is integrated to improve the mapping accuracy. Experiments show that the mapping accuracy is improved and the matching speed between two frames is reduced under loopback mapping. However, it does not affect real-time positioning and mapping, and can meet the requirements of real-time positioning and mapping in practical applications.

Effects of NCSTN Mutation on Hair Follicle Components in Mice.

BACKGROUND AND OBJECTIVES: Hidradenitis suppurativa (HS)/acne inversa is an intractable skin disease that is characterized by destructive lesions - primarily on the flexural areas. Although its etiology is unknown, genetics is considered to be a factor of its pathology - mutations in γ-secretase genes have been identified in certain familial HS patients, and follicular occlusion is widely accepted as the primary cause of HS. But, no relationship between these mutations and the components of hair follicles has been reported. Thus, we examined changes in these components in mice with a mutation in NCSTN (a γ-secretase gene). METHODS: We generated C57BL/6 mice with an NCSTN mutation and examined their expression of hair cortex cytokeratin and trichohyalin by Western blot and immunohistochemistry, in addition to nicastrin, the product of NCSTN, and NICD compared with wild-type mice. The structure of hair follicles was analyzed by hematoxylin-eosin staining and transmission electron microscopy. RESULTS: In mice with an NCSTN mutation, HS-like skin lesions appeared after age 6 months, the pathological manifestations of which were consistent with the features of human HS. The structure of hair follicles was abnormal in mice with an NCSTN mutation versus wild-type mice, and hair cortex cytokeratin, trichohyalin, nicastrin, and NICD were downregulated in these mice. CONCLUSIONS: This NCSTN mutant mouse model could be an improved model to study early lesion development aspects of human HS pathogenesis and could perhaps be a better alternative for evaluating early-acting and preventive therapeutics for HS experimentally before clinical trials in HS patients. NCSTN mutations disrupt the development of hair follicles, leading to abnormal hair follicle structures, perhaps resulting in the onset of HS.

Comparison of intravitreal injection of conbercept and triamcinolone acetonide for macular edema secondary to branch retinal vein occlusion.

AIM: To compare the safety and efficacy of the intravitreal injection of conbercept (IVC) and triamcinolone acetonide (IVTA) for macular edema (ME) secondary to branch retinal vein occlusion (BRVO). METHODS: A prospective, randomized clinical study. Patients with ME secondary to BRVO were randomly assigned to either IVC group or IVTA group at a ratio of 2:1 and a 12-month follow-up was performed. The efficacy outcome measures included the mean changes and differences in best corrected visual acuity (BCVA) and the central retinal thickness (CRT). The safety profiles and the mean retreatment intervals were also compared. RESULTS: There was no statistically significant difference of baseline between the two groups (IVC group, n=36; IVTA group, n=17). At 12mo, the BCVA letters improved by 27.31±18.36 in the IVC group, and 13.53±11.37 in the IVTA group (P=0.0004). CRT reduction was 253.33±163.69 and 150.24±134.32 µm, respectively (P=0.0034). The mean BCVA in the IVC group was superior to that of the IVTA group for months 6-12 (P<0.01). The mean CRT at 9 and 12mo were thinner in the IVC group compared to the IVTA group (P<0.01). The mean retreatment interval in the IVC group was longer than that in the IVTA group (97.40±36.27d vs 68.71±36.38d, P=0.0030). One eye in the IVC group and seven eyes in the IVTA group developed elevated intraocular pressure (IOP; P=0.0012). The proportion of eyes with cataract new-onset or progression were 19.44% in the IVC group and 64.71% in the IVTA group (P=0.0012). CONCLUSION: IVC could maintain or improve BCVA and reduce CRT for a longer time and have longer retreatment interval than IVTA. In addition, patients treated with IVTA are more susceptible to IOP elevation and cataract progression.

Why were doctors unable to accomplish their rural-aid mission in China? A qualitative study.

BACKGROUND: To alleviate the difficulties of rural residents in receiving timely healthcare, the Chinese government launched a medical rural-aid program that solicited urban medical professionals to go to rural hospitals for a 1-year tenure. However, many of urban doctors did not accomplish this task. In this study, we attempted to investigate the reasons behind the failure to fulfill this program and to explore a more feasible solution. METHODS: Eleven doctors and nurses participated in the focus group discussions. Twenty-five interviewees, including health administrative officials, doctors and managers from both urban tertiary hospitals and county-level hospitals, participated in semi-structured in-depth telephone interviews. The interview data were summarized and analyzed using the grounded theory. RESULTS: The failure of this program was attributed to multiple causes, such as problems with the recipient hospitals, the support hospitals and the participating doctors, and overall defects in the program strategy itself. One major reason is the competition between the recipient hospitals and the support hospitals, which distorted the original purpose of this rural-aid program. CONCLUSION: The rural-aid program strategy should be adjusted. The recipient hospitals should be township-level health centers rather than county-level hospitals. In addition, the relevant policies should be amended and improved accordingly. Copyright © 2015 John Wiley & Sons, Ltd.

Real-time EEG-based detection of fatigue driving danger for accident prediction.

This paper proposes a real-time electroencephalogram (EEG)-based detection method of the potential danger during fatigue driving. To determine driver fatigue in real time, wavelet entropy with a sliding window and pulse coupled neural network (PCNN) were used to process the EEG signals in the visual area (the main information input route). To detect the fatigue danger, the neural mechanism of driver fatigue was analyzed. The functional brain networks were employed to track the fatigue impact on processing capacity of brain. The results show the overall functional connectivity of the subjects is weakened after long time driving tasks. The regularity is summarized as the fatigue convergence phenomenon. Based on the fatigue convergence phenomenon, we combined both the input and global synchronizations of brain together to calculate the residual amount of the information processing capacity of brain to obtain the dangerous points in real time. Finally, the danger detection system of the driver fatigue based on the neural mechanism was validated using accident EEG. The time distributions of the output danger points of the system have a good agreement with those of the real accident points.

A randomized controlled trial of combination treatment with ketoconazole 2% cream and adapalene 0.1% gel in pityriasis versicolor.

BACKGROUND: Ketoconazole cream and adapalene gel are effective drugs against pityriasis versicolor. However, there are no reports on combination treatment with both compounds in pityriasis versicolor. OBJECTIVE: To evaluate the efficacy and safety of combination therapy with adapalene 0.1% gel and ketoconazole 2% cream against pityriasis versicolor. METHODS: Participants with pityriasis versicolor were randomly assigned to two groups: the combination group was treated with adapalene 0.1% gel and ketoconazole 2% cream once daily, and the monotherapy group received ketoconazole 2% cream twice daily. The treatment lasted 2 weeks in both groups. Outcomes were assessed at baseline and 1, 2 and 4 weeks after the initiation of treatment. RESULTS: We noted clinically significant differences in total improvement rates between groups Weeks 1 and 2. A statistically significant difference was obtained Week 4. The treatment was well tolerated by all participants. CONCLUSIONS: The combination of adapalene 0.1% gel and ketoconazole 2% cream is effective and safe in the treatment of pityriasis versicolor. This therapeutic regimen was rapid, providing a valuable option for patients with pityriasis versicolor.

Combination treatment of oral terbinafine with topical terbinafine and 10% urea ointment in hyperkeratotic type tinea pedis.

Hyperkeratotic-type tinea pedis is chronic and recalcitrant to topical antifungal agents. Some topical antifungal agents are effective; however, long duration of therapy is required, which often reduce the treatment compliance of patients. To seek for short period therapy of hyperkeratotic type tinea pedis, in this study, we observed the efficacy and safety of treatment of topical terbinafine and 10% urea ointment combined oral terbinafine. Participants with hyperkeratotic type tinea pedis were randomly assigned to two groups. Patients in group I were treated with oral terbinafine for 2 weeks and topical terbinafine and 10% urea ointment for 4 weeks, whereas in group II, only the above topical agents were applied for 12 weeks. Clinical improvement rates and fungal eradication rates were compared between the two groups at 24 weeks after the initiation of treatment. The group I had stopped the topical therapy 8 weeks earlier than group II. There were no significant differences in mycological eradication rates and clinical improvement rates between the two groups, besides, no major side effects were noted in both groups. The short combination therapy with oral terbinafine was effective and safe; it should be a valuable option for patients with hyperkeratotic type tinea pedis.

Roles of adapalene in the treatment of pityriasis versicolor.

BACKGROUND: Ketoconazole is a typical treatment available for pityriasis versicolor; tretinoin cream is effective, too. Adapalene gel is a tretinoin derivative and has a lower incidence of irritation compared with other topical retinoid products. However, there are no reports on adapalene gel for the treatment of pityriasis versicolor. OBJECTIVE: To study the effect of adapalene gel comparing the treatment with adapalene gel and 2% ketoconazole cream in pityriasis versicolor. METHODS: Eighty patients suffering from pityriasis versicolor were randomly divided into two groups; one group were treated with 2% ketoconazole cream topically twice daily for 2 weeks, adapalene gel was used for the other group in a similar fashion. RESULTS: There were no significant differences in efficacy between the two groups. No major side effects were noted in any of the groups either. CONCLUSION: Adapalene was the favorable option in the treatment of pityriasis versicolor. The probable therapeutic mechanism of adapalene is also discussed.