Template-Guided Hierarchical Multi-View Registration Framework of Unordered Bridge Terrestrial Laser Scanning Data.

The registration of bridge point cloud data (PCD) is an important preprocessing step for tasks such as bridge modeling, deformation detection, and bridge health monitoring. However, most existing research on bridge PCD registration only focused on pairwise registration, and payed insufficient attention to multi-view registration. In addition, to recover the overlaps of unordered multiple scans and obtain the merging order, extensive pairwise matching and the creation of a fully connected graph of all scans are often required, resulting in low efficiency. To address these issues, this paper proposes a marker-free template-guided method to align multiple unordered bridge PCD to a global coordinate system. Firstly, by aligning each scan to a given registration template, the overlaps between all the scans are recovered. Secondly, a fully connected graph is created based on the overlaps and scanning locations, and then a graph-partition algorithm is utilized to construct the scan-blocks. Then, the coarse-to-fine registration is performed within each scan-block, and the transformation matrix of coarse registration is obtained using an intelligent optimization algorithm. Finally, global block-to-block registration is performed to align all scans to a unified coordinate reference system. We tested our framework on different bridge point cloud datasets, including a suspension bridge and a continuous rigid frame bridge, to evaluate its accuracy. Experimental results demonstrate that our method has high accuracy.

Application of 3D Printing Navigation Template Technology in Severe Hallux Valgus Surgery.

OBJECTIVES: To explore the application of 3D printed navigation template technology in severe Hallux valgus surgery. METHODS: Forty-eight patients with severe Hallux valgus were selected. There were 24 cases in the control group underwent hallux valgus osteotomy using traditional methods and fixed with fully threaded hollow screws during the surgery. There were 24 cases in the 3D group who underwent personalized osteotomy using 3D printing navigation template technology. Patients were followed up regularly for six months after surgery. RESULTS: The surgery time of the 3D group was shorter than that of the control group, and the intraoperative bleeding was reduced (P<0.05). Compared with the preoperative data, the HVA and IMA significantly reduced immediately and 1, 3, and 6 months after surgery (P<0.05). The VAS scores decreased significantly, while the AOFAS and SF-36 scores increased (P<0.05). At three months and six months after surgery, the VAS score of the 3D group was lower than that of the control group, while the SF-36 score was higher (P<0.05). During the follow-up period, both groups had no recurrent cases or complications. CONCLUSIONS: The 3D printing navigation template technology improves patients' prognosis, functional recovery, and quality of life.

Study on Mechanical Failure Behavior of Steel-Wire Wound Reinforced Thermoplastic Pipe under Combined Internal Pressure and Soil Landslide Conditions.

A steel-wire wound reinforced thermoplastic pipe (SWW-RTP) has been widely utilized in many industrial areas, and a soil landslide is an inevitable hazardous extreme condition for the SWW-RTP as it is usually buried underground. It is imperative to study the mechanical failure behavior and the failure criterion of the SWW-RTP under the combination of internal pressure and soil landslide conditions, and this paper is the first study to investigate the topic. In this paper, groups of stress-strain curves of high-density polyethylene (HDPE) and steel wires were obtained by uniaxial tensile tests at different strain rates, with the help of a Digital Image Correlation device (DIC). A rate-dependent constitutive model was employed to represent the mechanical behavior of the HDPE and to help deduce the stress-strain curve of the HDPE under the required strain rate, estimated from the static simplification of the dynamic soil landslide. Afterwards, a finite element model of the SWW-RTP, embedded in a cubic of soil, was established with the software ABAQUS. The SWW-RTP model was composed of HDPE solid elements, embedded with steel-wire truss elements, and the soil was characterized with the extended Drucker-Prager model. A quartic polynomial displacement distribution was applied to the soil model to represent the soil landslide. Then, the mechanical response of the SWW-RTP was analyzed. It was found that the failure criterion of the HDPE yield was more suitable for the pipe subjected to internal pressure and soil landslide conditions, instead of the steel-wire strength failure criterion always used in traditional research on the SWW-RTP. Further, the influence of landslide width, internal pressure and steel-wire number were discussed. The larger the width of the landslide area, the gentler the deformation of the pipeline; this resulted in an increase in the maximum landslide and a decrease in the maximum curvature with the width of the landslide area. The relatively high internal pressure was beneficial to the safety of the SWW-RTP under landslide, because the internal pressure could increase the stiffness of the pipeline. The number of steel wires had a limited influence on the maximum landslide required for the SWW-RTP's failure. This work can be useful for the design and safe assessment of the SWW-RTP under internal pressure and soil landslide conditions.

Farmers' Preference for Participating in Rural Solid Waste Management: A Case Study from Shaanxi Province, China.

Rural solid waste management is an important method to improve rural living environments. Farmers' participation in rural solid waste management plays an essential role in sustainable waste management. Based on the micro-survey data of 592 farmers in Shaanxi province, a multinomial logit model was applied to explore farmers' preferences for participating in rural solid waste management. The empirical results show that both institutional and interpersonal trust have significant positive effects on farmers' payment participation, and labor and payment participation. Among environmental awareness, farmers with pro-environmental behavior prefer labor participation, and labor and payment participation; the more environmental knowledge farmers have, the stronger their preferences for payment participation, labor and payment participation, and labor participation; farmers concerned about environmental problems are more inclined to adopt labor and payment participation or payment participation. For socio-demographic characteristics, gender has no significant influence, while agricultural net income and education can significantly increase farmers' willingness to participate; farmers who have migrant work experience prefer to participate in payment; there are obvious intergenerational differences in the influence of social trust and environmental awareness on farmers' participation preference. Therefore, providing diversified participation modes, creating a good social trust environment, and enhancing farmers' awareness of environmental care are important in promoting rural solid waste management.

What Factors Affect Farmers' Levels of Domestic Waste Sorting Behavior? A Case Study from Shaanxi Province, China.

Waste sorting is a key element for solving the current predicament of rural waste management. In the pilot areas of China, farmers' domestic waste sorting behavior (DWSB) varies significantly, whereas there are few studies exploring the mechanism of its formation. To fill this research gap, this study constructs a research model of the internal logic of farmers' waste sorting levels (i.e., no sorting; sorting recyclable waste; sorting recyclable and kitchen waste; and sorting recyclable, kitchen, harmful, and other waste) by considering circumstantial constraints (social norms in external factors) and psychological behavioral antecedents (personal norms and group identity in internal factors). Based on pilot survey data from farmers in Shaanxi Province, China, the results of the ordered logit model indicate that social norms and personal norms were the most significant predictors of the level of DWSB, while group identity was found to have no significant influence. Furthermore, the results of the grouping regression analysis showed that personal norms had a positive moderating effect on the relationship between social norms and farmers' DWSB. Therefore, a more positive social atmosphere, better education, and personal environmental moral responsibility for domestic waste sorting should be established to enhance their levels of waste sorting behavior.

A modified three-incision approach to treating three-column Lisfranc injuries.

PURPOSE: The most popular surgical approach to manage Lisfranc fracture-dislocations is the double-incision approach, which frequently causes a variety of complications, such as skin necrosis, rotational malreduction of the first tarsometatarsal joint (TMTJ) and lateral column dorsoplantar malreduction of the TMTJ. We introduce a three-incision approach to treat Lisfranc fracture-dislocations with only minor postoperative complications and good foot function. METHODS: We prospectively selected 30 previously healthy patients, ranging from 18 to 60 years of age, but only 23 patients completed the follow-up and thus were finally included, with an average age of 38.1 ± 12.9 years. All patients have sustained Lisfranc fracture-dislocations involving all three-column; 13.0% (3/23) were Myerson classification type A (medial), 47.8% (11/23) were type A (lateral), and 39.1% (9/23) were type C2. All patients were treated via a three-incision approach: a long incision made along the lateral border of the second ray was used as a working incision to visualize and reduce the first three TMTJs, as well as to apply internal fixation instrumentation; a 2 cm medial incision was made at the medial side of the first TMTJ as an inspecting incision, ensuring good reduction of the first TMTJ in medial and plantar view; another 1 cm inspecting incision was made at the dorsal side of the fourth/fifth TMTJ to prevent sagittal subluxation of the lateral column. Mean ± SD was used for quantitative data such as operation time, follow-up time and foot function scores. Postoperative complications were documented, and foot function was evaluated using the American orthopaedic foot & ankle society score, foot function index and Maryland foot score at follow-up. The foot function of the injured foot and contralateral foot of the same patient was at the end of follow-up, and independent sample t-test was used for statistical analysis. RESULTS: The median operation time was 117.9 ± 14.6 min (range 93 - 142 min). All complications occurred within three months after the operation, and included delayed wound healing (17.4%), superficial infection (8.7%), complex regional pain syndrome (4.3%) and neuroma (4.3%). There was no case of postoperative skin necrosis or malreduction. At the end of follow-up of 14.1 ± 1.2 months (range 12-16 months), the median American orthopaedic foot & ankle society score of the operated foot was 89.7 ± 5.7, the median foot function index was 21.7 ± 9.9, and the median Maryland foot score was 88.7 ± 4.8. There were no significant differences between the operated and contralateral sides, in terms of foot function, at the end of followup (p > 0.05). CONCLUSION: The three-incision approach can provide adequate visualization of all TMTJs to ensure anatomical reduction and offer sufficient working space to apply internal fixation instrumentation, which is effective in treating three-column Lisfranc fracture-dislocations with minor soft tissue complications and satisfactory functional recovery.

Multi-Sensor Fusion by CWT-PARAFAC-IPSO-SVM for Intelligent Mechanical Fault Diagnosis.

A new method of multi-sensor signal analysis for fault diagnosis of centrifugal pump based on parallel factor analysis (PARAFAC) and support vector machine (SVM) is proposed. The single-channel vibration signal is analyzed by Continuous Wavelet Transform (CWT) to construct the time-frequency representation. The multiple time-frequency data are used to construct the three-dimension data matrix. The 3-level PARAFAC method is proposed to decompose the data matrix to obtain the six features, which are the time domain signal (mode 3) and frequency domain signal (mode 2) of each level within the three-level PARAFAC. The eighteen features from three direction vibration signals are used to test the data processing capability of the algorithm models by the comparison among the CWT-PARAFAC-IPSO-SVM, WPA-PSO-SVM, WPA-IPSO-SVM, and CWT-PARAFAC-PSO-SVM. The results show that the multi-channel three-level data decomposition with PARAFAC has better performance than WPT. The improved particle swarm optimization (IPSO) has a great improvement in the complexity of the optimization structure and running time compared to the conventional particle swarm optimization (PSO.) It verifies that the proposed CWT-PARAFAC-IPSO-SVM is the most optimal hybrid algorithm. Further, it is characteristic of its robust and reliable superiority to process the multiple sources of big data in continuous condition monitoring in the large-scale mechanical system.

Comparative Study on Flow-Accelerated Corrosion and Erosion-Corrosion at a 90° Carbon Steel Bend.

Electrochemical measurements and surface analysis are performed to comparatively study flow-accelerated corrosion (FAC) and erosion-corrosion (E-C) behavior at a 90° carbon steel bend. The corrosion rates are higher under FAC conditions than those under E-C conditions. For FAC, the corrosion is more serious at the inside wall. However, corrosion is exacerbated at the outside wall under E-C conditions. No erosion scratches are observed under FAC conditions and at the inside wall under E-C conditions, while remarkable erosion scratches appear at the outside wall under E-C conditions. The dominant hydrodynamics affecting FAC and E-C are remarkably different.