The development characteristics and mechanisms of the Xigou debris flow in the Three Gorges Reservoir Region

Debris flow is a common geological hazard in mountainous areas of China, often causing secondary disasters and seriously threatening residents and infrastructure. This paper uses the Xigou debris flow in the Three Gorges Reservoir Region (TGRR) as an example case study, the development characteristics and initiation pattern of which were analyzed based on field investigation. The disaster dynamics software DAN-W was then used to simulate the entire initiation-movement-accumulation process of the debris flow and conduct the debris flow dynamics analysis. The paper also simulated and predicted the movements of landslides in the formation area of a debris flow after its initiation. The results show that the movement duration of the Xigou debris flow was approximately 40 s, the maximum velocity was 37.1 m/s, the maximum thickness of the accumulation was 18.7 m, and the farthest movement distance was 930 m, which are consistent with the field investigation. When the volumes of landslide transformed into a new source material of debris flow are 5 × 104, 10 × 104, 15 × 104, 20 × 104, and 26 × 104 m3, the movement distances of the debris flows are 250, 280, 300, 340, and 375 m, respectively. When the volume of the source material exceeds 20 × 104 m3, debris flow movement can seriously impact the residential houses at the entrance of the gully. This paper can provide a scientific basis for the prevention and mitigation of the Xigou debris flow

Case report: Fully endoscopic microvascular decompression for glossopharyngeal neuralgia

With the advances in endoscopic technology, endoscopy is widely used in many neurosurgical procedures, such as microvascular decompression, which is an effective method to treat glossopharyngeal neuralgia, trigeminal neuralgia, and facial spasm. The purpose of this study was to determine the efficacy of fully endoscopic microvascular decompression in the treatment of glossopharyngeal neuralgia. We managed a patient with glossopharyngeal neuralgia in our department, whose main clinical manifestation was recurrent left ear and facial pain for 3 years. The patient underwent a fully endoscopic microvascular decompression. The pain in the left ear and face was significantly relieved postoperatively, and there was no recurrence at the 6-month follow-up evaluation. We describe a case of glossopharyngeal neuralgia that was successfully treated by fully endoscopic microvascular decompression, which showed that endoscopy has advantages in microvascular decompression, and fully endoscopic microvascular decompression is an effective method for glossopharyngeal neuralgia

Kinetic Study on the Pyrolysis of Medium Density Fiberboard: Effects of Secondary Charring Reactions

The reaction models employed in the kinetic studies of biomass pyrolysis generally do not include the secondary charring reactions. The aim of this work is to propose an applicable kinetic model to characterize the pyrolysis mechanism of medium density fiberboard (MDF) and to evaluate the effects of secondary charring reactions on estimated products yields. The kinetic study for pyrolysis of MDF was performed by a thermogravimetric analyzer over a heating rate range from 10 to 40 °C/min in a nitrogen atmosphere. Four stages related to the degradation of resin, hemicellulose, cellulose, and lignin could be distinguished from the thermogravimetric analyses (TGA). Based on the four components and multi-component parallel reaction scheme, a kinetic model considering secondary charring reactions was proposed. A comparison model was also provided. An efficient optimization algorithm, differential evolution (DE), was coupled with the two models to determine the kinetic parameters. Comparisons of the results of the two models to experiment showed that the mass fraction (TG) and mass loss rate (DTG) calculated by the model considering secondary charring reactions were in better agreement with the experimental data. Furthermore, higher product yields than the experimental values will be obtained if secondary charring reactions were not considered in the kinetic study of MDF pyrolysis. On the contrary, with the consideration of secondary charring reactions, the estimated product yield had little error with the experimental data

Seismic Signal Characteristics and Numerical Modeling Analysis of the Xinmo Landslide

Due to the high elevation and huge potential energy of high-level landslides, they are extremely destructive and have prominent kinetic-hazard effects. Studying the kinetic-hazard effects of high-level landslides is very important for landslide risk prevention and control. In this paper, we focus on the high-level landslide that occurred in Xinmo on 24 June 2017. The research is carried out based on a field geological survey, seismic signal analysis, and the discrete element method. Through ensemble empirical mode decomposition (EEMD) and Fourier transformation, it is found that the seismic signals of the Xinmo landslide are mainly located at low frequencies of 0–10 Hz, and the dominant frequency range is 2–8 Hz. In addition, the signal time-frequency analysis and numerical simulation calculation results reveal that the average movement distance of the sliding body was about 2750 m, and the average movement speed was about 22.9 m/s. The movement process can be divided into four main stages: rapid start, impact loading, fragmentation and migration, and scattered accumulation stages. We also provide corresponding suggestions for the zoning of high-level landslide geological hazards

Differential Diffusion Effects in Numerical Simulations on Smoke Toxicity Evaluation

With the increasing frequency of fire caused by construction materials, smoke toxicity evaluation plays a key role in related fields. Numerical simulation has become a popular method to predict the toxicity of smoke. A computational study of differential diffusion effects on smoke toxicity evaluation is proposed in this study. Further, an effective Lewis number model derived from the Reynolds-averaged form of the Navier-stokes (RANS) transport equations is proposed in turbulent flames. The accuracy of the study is illustrated for a polyurethane foam fire in a 1/5 scale vertical shaft. The temperature and the concentrations of smoke composition are mainly discussed. From the comparison of the calculations with the direct numerical simulations (DNS) data it is observed that the temperature and mass fractions of species agree well with the DNS data when differential diffusion effects are taken into account. On the other hand, these numerical results are overestimated if differential diffusion effects are neglected. The FED values indicate that differential diffusion has a strong influence on smoke toxicity evaluation when using N-Gas model

Differential Diffusion Effects in Numerical Simulations on Smoke Toxicity Evaluation

With the increasing frequency of fire caused by construction materials, smoke toxicity evaluation plays a key role in related fields. Numerical simulation has become a popular method to predict the toxicity of smoke. A computational study of differential diffusion effects on smoke toxicity evaluation is proposed in this study. Further, an effective Lewis number model derived from the Reynolds-averaged form of the Navier-stokes (RANS) transport equations is proposed in turbulent flames. The accuracy of the study is illustrated for a polyurethane foam fire in a 1/5 scale vertical shaft. The temperature and the concentrations of smoke composition are mainly discussed. From the comparison of the calculations with the direct numerical simulations (DNS) data it is observed that the temperature and mass fractions of species agree well with the DNS data when differential diffusion effects are taken into account. On the other hand, these numerical results are overestimated if differential diffusion effects are neglected. The FED values indicate that differential diffusion has a strong influence on smoke toxicity evaluation when using N-Gas model

Comparison between OLIF and MISTLIF in degenerative lumbar stenosis: an age-, sex-, and segment-matched cohort study

Abstract To compare outcomes after oblique lateral interbody fusion (OLIF) versus minimally invasive transforaminal lumbar interbody fusion (MISTLIF) with bilateral decompression via unilateral approach for treating mild to moderate symptomatic degenerative lumbar spinal stenosis (DLSS). We retrospectively compared patients who underwent single-level (L4/5) OLIF with an age-, sex-, and segment-matched MISTLIF with bilateral decompression via unilateral approach cohort. Perioperative data were collected for the operative time, intraoperative blood loss, drainage in the first postoperative day, postoperative hospital stay, cost, intraoperative fluoroscopy, and complications. Lumbar radiographs were measured for changes in posterior intervertebral space height (PISH), intervertebral space foramen height (IFH), intervertebral foramen area (IFA), and area of the spinal canal (ASC). Clinical and psychological outcomes included the visual analog scale (VAS), Oswestry Disability Index (ODI), and hospital anxiety and depression scale (HADS). 35 OLIF patients were compared with 35 MISTLIF patients in L4/5 DLSS. The OLIF group had shorter bedtime, postoperative hospital stays, less intraoperative and postoperative blood loss (all P < 0.05), but had more times of intraoperative fluoroscopy, longer operative time, and higher cost (all P < 0.05). The complication rates were equivalent (OLIF vs MISTLIF: 22.86% vs 17.14%). PISH (11.94 ± 1.78 mm vs 9.42 ± 1.94 mm, P < 0.05), IFH (23.87 ± 3.05 mm vs 21.41 ± 2.95 mm, P < 0.05), and IFA (212.14 ± 51.82 mm2 vs 177.07 ± 51.73 mm2, P < 0.05) after surgery were significantly increased in the OLIF group. The ASC was increased significantly after the operation in both groups, but the ASC in the MISTLIF group was increased significantly more than that in the OLIF group (450.04 ± 66.66 mm2 vs 171.41 ± 58.55 mm2, P < 0.05). The lumbar VAS scores at 1 month (1.89 ± 0.87 vs 2.34 ± 0.84, P = 0.028) and 6 months (1.23 ± 0.97 vs 1.80 ± 0.99, P = 0.018) after operation in the OLIF group were significantly lower. There were no significant differences in lower extremity VAS and ODI scores between the two groups. Compared with MISTLIF group, HADS scores on postoperative day 3 (2.91 ± 1.46 vs 4.89 ± 1.78, P < 0.05) and prior to hospital discharge (PTD) (2.54 ± 1.38 vs 3.80 ± 1.78, P = 0.002) in the OLIF group were decreased significantly. OLIF showed more advantages of less surgical invasion, lower incidence of postoperative low back pain, faster postoperative recovery, and less anxiety compared with MISTLIF. Regardless of cost, OLIF seems to be a better option to treat mild to moderate symptomatic DLSS