Modeling distracted driving behavior considering cognitive processes.

The modeling of distracted driving behavior has been studied for many years, however, there remain many distraction phenomena that can not be fully modeled. This study proposes a new method that establishes the model using the queuing network model human processor (QN-MHP) framework. Unlike previous models that only consider distracted-driving-related human factors from a mathematical perspective, the proposed method reflects the information processing in the human brain, and simulates the distracted driver's cognitive processes based on a model structure supported by physiological and cognitive research evidence. Firstly, a cumulative activation effect model for external stimuli is adopted to mimic the phenomenon that a driver responds only to stimuli above a certain threshold. Then, dual-task queuing and switching mechanisms are modeled to reflect the cognitive resource allocation under distraction. Finally, the driver's action is modeled by the Intelligent Driver Model (IDM). The model is developed for visual distraction auditory distraction separately. 773 distracted car-following events from the Shanghai Naturalistic Driving Study data were used to calibrate and verify the model. Results show that the model parameters are more uniform and reasonable. Meanwhile, the model accuracy has improved by 57% and 66% compared to the two baseline models respectively. Moreover, the model demonstrates its ability to generate critical pre-crash scenarios and estimate the crash rate of distracted driving. The proposed model is expected to contribute to safety research regarding new vehicle technologies and traffic safety analysis.

Drying characteristics of sewage sludge pre-conditioned by CaO and sawdust under low-temperature drying conditions.

Heat pump drying is a low-carbon method of sludge drying. The operating temperature of a heat pump is generally not more than 70℃. To improve the drying efficiency of heat pump dryers, the effects of air parameters and additives on sludge drying characteristics at low temperatures were studied. The sludge drying experiments were conducted at an air temperature 50-70℃ and an air velocity of 0.5-1.7 m/s. The experimental results showed that the increase of air temperature, velocity and the addition ratio of additives can accelerate the sludge drying process. The average and maximum drying rates of sludge pre-conditioned by CaO and sawdust increased by 14.23% and 25.71%, respectively, compared with those of pure sludge. The two-way analysis of variance (ANOVA) revealed that the influence of air temperature on the sludge drying was higher than that of air velocity. Five reference models were fitted by the drying experiment data. The Page model has the highest R2, so it is the most suitable model to predict the drying time of sludge at low temperatures.

Microstructure and Tensile Property of Laser Cladding Assisted with Multidimensional High-Frequency Vibration.

Laser cladding is a promising surface modification technology to fabricate high-performance parts. However, defects such as porosity, cracks and residual tensile stress are easily produced in laser cladding, leading to significant property reduction and poor reliability. In this study, laser cladding with multidimensional high-frequency vibration was investigated. The effects of multidimensional high-frequency vibration on the improvement of microstructure and mechanical properties were analyzed and discussed based on the vibration-assisted laser cladding experiments. In addition, a numerical model was conducted to help understand the significance of the vibration on flow field and temperature field. Results show that 3D vibration led to the primary dendrite spacing reduction from 11.1 to 6.8 µm, microhardness increase from 199 to 221 HV0.2, and a nearly 110% improvement in the elongations. The findings of this study confirmed the significant benefits of multidimensional high-frequency vibration applied in laser cladding and provided a basis to uncover the underlying mechanisms of multidimensional vibration on the rapid melting and solidification.

[Clinical application of percutaneous spinal endoscopy debridement and lavage in sacroiliac joint tuberculosis].

OBJECTIVE: To investigate the feasibility and clinical efficacy of percutaneous spinal endoscopic debridement and lavage for the treatment of sacroiliac joint tuberculosis. METHODS: The clinical data of 7 patients with sacroiliac joint tuberculosis treated with percutaneous spinal endoscopic debridement and lavage from January 2007 to April 2009 were retrospectively analyzed. There were 2 males and 5 females, aged from 29 to 69 years old, 4 cases on the right side of the lesion and 3 cases on the left side. The course ranged from 8 to 144 months. According to Kim classification, 5 cases were type Ⅲ and 2 cases were type Ⅳ. All patients were treated with HRZE quadruple anti tuberculosis drugs for 2 to 6 weeks beforeoperation. VAS, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and Oswestry Disability Index (ODI) were compared before and after surgery. RESULTS: All the operations were successful, the intraoperative blood loss was less than 50 ml on average, and no complications such as hematoma and infection were occurred. The follow-up time of 7 cases ranged from 18 to 40 months. Pain relief was obvious, and there was a statistical result in the VAS, ESR, and ODI of the patients at 1, 3, 6, 12, 18 months after operation compared with before treatment. At the final follow-up, the patient's clinical, imaging and laboratory examinations showed that the infection had disappeared, and the patient returned to normal life and work. CONCLUSION: Percutaneous spine endoscopic debridement and lavage has less tissue trauma, targeted operation, definite curative effects, and quick postoperative recovery, which has explored new options for minimally invasive treatment of sacroiliac joint tuberculosis.

Blind-zone formation in laser shockwave nano-cleaning.

Laser shockwave cleaning (LSC) has attracted growing attention due to its advantages in non-contact, site-selective nanoparticle removal on microelectronic/optical devices. However, an uncleaned blind-zone formed directly under the laser-induced plasma kernel severely affects the cleaning effect. Laser shockwave cleaning of 300 nm polystyrene latex nanoparticles on silicon wafers is fully explored to understand the blind-zone formation mechanism. The size of the uncleaned blind-zone quickly increases from 0.84 to 19.50 mm2 associated with a growing fraction of the uncleaned blind-zone area within the whole cleaned area from 0.05 to 0.93 as the plasma-substrate gap distance is increased from 0.5 to 2 mm and the laser fluence is increased from 75 to 150 J/cm2. Besides, the variation of the blind-zone size is more strongly dependent on the plasma-substrate gap distance than the laser fluence. A time-resolved analysis of the laser-induced plasma evolution shows an inseparable relationship between the blind-zone and the geometric location of the plasma kernel. Theoretical analysis of the removal force in LSC based on the rolling mode reveals that the lack of dragging force acting on the nanoparticles in the region right under the plasma kernel impedes their removal and causes the uncleaned blind-zone formation.

Hot Corrosion and Mechanical Performance of Repaired Inconel 718 Components via Laser Additive Manufacturing.

Hot corrosion is one of the crucial failure modes of Ni-based superalloy components operating at high temperatures, which inevitably affects the subsequent mechanical properties of the alloys. In this research, damaged Inconel 718 alloy components with a pre-made trapezoid groove are repaired using laser additive manufacturing technique, and the change mechanisms of the microstructure and tensile properties of the repaired Inconel 718 alloy due to the hot corrosion in the salt mixture of 87.5 wt.% Na2SO4 + 5 wt.% NaCl + 7.5 wt.% NaNO3 at 650 °C for different durations are investigated. The results show that oxidation and Cr-depletion occur on the repaired components due to the hot corrosion, and the corrosion products are mainly composed of Cr2O3, Fe3O4, and Ni3S2. The tensile strength and elongation of the as-repaired specimens are 736.6 MPa and 12.5%, respectively. After being hot corroded for 50 h, the tensile strength increases to 1022.9 MPa and elongation decreases to 1.7%. However, after being hot corroded for 150 h, both tensile strength and elongation of the repaired specimens drop to 955.8 MPa and 1.2%, respectively. The mechanical performance alteration is highly related to thermal effects instead of the molten salt attack.

Core decompression combined with autologous bone marrow stem cells versus core decompression alone for patients with osteonecrosis of the femoral head: A meta-analysis.

BACKGROUND: The efficacy of core decompression plus autologous bone mesenchymal stem cells (BMSCs) for the treatment of osteonecrosis of the femoral head (ONFH) remains controversial. We conducted a systematic review and meta-analysis to explore the efficacy of core decompression combined with BMSCs for OFNH patients. METHODS: We searched PubMed, Embase, Web of Science, and the Cochrane library databases through October 2018 for randomized controlled trials (RCTs) assessing the effect of core decompression combined with BMSCs for OFNH patients. The primary outcome was the visual analog scale (VAS) score at 6 months, 12 months and 24 months. The pooled data were analyzed using Stata 12.0 software. RESULTS: Fourteen studies with 540 patients (core decompression + BMSCs = 275, core decompression alone = 265) were included in our meta-analysis. Compared with the core decompression alone group, the core decompression + BMSCs group showed a significant decrease in the VAS score at 6 months, 12 months and 24 months, and a decrease in the number of hips undergoing total hip arthroplasty (THA), the Western Ontario and McMaster Universities (WOMAC) score and the volume of the postoperative necrotic zone. Core decompression + autologous BMSCs was associated with an increase in HHS postoperatively. No significant difference existed in adverse events. CONCLUSIONS: Compared with core decompression alone in the treatment of ONFH, the combined utilization of core decompression and autologous BMSCs has better pain relief and clinical outcomes and can delay the collapse of the femoral head more effectively.

Interaction between the laser beam and keyhole wall during high power fiber laser keyhole welding.

The crucial factor of laser welding is the laser energy conversion. For a better understanding of the process, the interaction process between the laser beam and keyhole wall was investigated by observing the keyhole wall evaporation during high-power fiber laser welding. The results show that the evaporation vapor, induced by the laser beam, discretely distributed on the keyhole wall. A tiny 'hollow' zone was observed at the spot center-action region on the FKW. The evaporation vapor induced by the spot center moved downward along the front keyhole wall (FKW) with a period of about 0.3~0.75 ms, which indicates that the keyhole formation is reminiscent of a periodical laser drilling process on the FKW. The evaporation vapor on the keyhole wall suggest the assumption that the laser energy coupling mode in the keyhole was multiple-reflection, and the keyhole depth was mainly determined by the drilling behavior induced by the first absorption on the FKW.

[Progress on research of Madelung's deformity].

Madelung deformity is a rare deformity of forearm and wrist caused by growth disorders of distal radius ulnar and palmar epiphyseal. Current studies showed that its incidence mainly associated with trauma, epiphyseal developmental abnormalities, nutritional disorders and genetic deletion or mutation. The early clinical presentation is not typical, in middle and late time, wrist deformity and weak can appear. Plain film considered as the main means of diagnosis is often lack of early diagnosis significance. Although wrist joint magnetic resonance imaging showing early soft tissue and skeletal abnormalities were used for the early diagnosis of the disease, current domestic study in magnetic resonance imaging of this deformity is less. According to the size of the distal ulnar inclination angle and palm angle, this deformity can be divided into different types. The patients with severe deformity and symptoms usually need surgical intervention including ulna revision and osteotomy of the distal radius at present. Although the two operation can achieve good clinical results, the surgical trauma, infection and postoperative risk of joint activities are more.