Search

With the highly intelligent development of the manufacturing industry, assembly problems have become one of the reasons for the high cost of products. One of the main challenges in the automatic planning of assembly sequences is the identification of sub-assembly. The sub-assembly identification can effectively realize the parallel development and planning of the assembly. In the paper, the focus is concentrated on a sub-assembly recognition algorithm. It is used to recognize the sub-assemblies in various assemblies in order to simplify assembly sequence and decrease assembly difficulty and costs. Firstly, the principle of sub-assembly recognition algorithm is clarified, and the structural information model of the assembly is defined by the weighted undirected connection graph. It is then converted into an adjacency incidence matrix to judge the membership relations between parts in the assembly. Second, mathematical modeling is performed according to the process and principle of sub-assembly recognition. Thirdly, the sub-assembly recognition algorithm is programmed in Matlab, and the feasibility of the algorithm is verified by an example. Finally, the sub-assembly center initialization, the quantity of sub-assemblies c, and the fuzzy index m among the important factors in the algorithm are selected to analyze the parameters and optimize the parameters.

Rationale: Hemangioblastomas in the kidney are rare. Although a few cases of renal hemangioblastoma (RH) have been reported, the content of these articles mainly focused on clinical and pathological research, with minimal descriptions of radiologic findings. Moreover, there are no descriptions of magnetic resonance imaging (MRI) with enhancement of this condition. Herein, we report 2 cases of RH with computed tomography (CT) and MRI findings. Patient concerns: Two patients presented to our institution because of dull pain in the left abdomen, and a mass in the left kidney was found by ultrasound examination in each case. The patient had no special family history. Physical examination revealed no obvious tenderness or percussion pain in the renal and ureteral walking areas, and there was no obvious mass. Routine blood and urine tests were normal, and the serum tumor markers were negative. No obvious lesions were found on imaging of the other body parts. Diagnosis: Similar radiologic findings were observed in both cases and mimicked those of cavernous hemangiomas of the liver, including peripheral nodular enhancement in the corticomedullary phase, progressive centripetal enhancement in the nephrographic and delayed phases, and occasional complete “filling in” in the delayed phase. We made a radiologic diagnosis of renal clear cell carcinoma for patient 1 and suspected renal clear cell carcinoma for patient 2, but the pathological results showed RH. Interventions: Given the suspicion of renal cell carcinoma, both patients underwent partial nephrectomy. Outcome: The recovery of the two patients was uneventful, and there was no evidence of local recurrence or metastasis many years after surgery. Lessons: RH is a rare benign tumor that can be easily misdiagnosed as clear cell carcinoma. Characteristic CT and MRI manifestations may improve preoperative diagnostic accuracy to avoid surgery or indicate nephron-sparing surgery.

Ground transportation means and aircrafts with high-speed running are composed of many rod components. Aerodynamic noise generated therefrom is very outstanding. Reduction of the aerodynamic noise of rods becomes a hot topic in recent years. Most reported studies are tentative researches on aerodynamic noise of a pantograph or involve noise reduction of the pantograph with using porous materials or reshaping rod surfaces. Through using porous materials and reshaping rod surface, the aerodynamic noise of pantograph can be reduced to a certain extent, but the aerodynamic resistance will be increased and it is not convenient for practical application in engineering. Regarding this situation, the paper explores noise reduction performance of a feather on the back of a carrier pigeon and conducts the bionic design on rod surface. Through numerical simulation, the paper researches noise reduction performance of the bionic structure on the rod surface, reveals the mechanism of bionic noise reduction, and explores noise reduction effects of bionic structural rods on pantographs of the high-speed trains.

According to the problem that the elevation data does not reflect the slope and surface roughness of target topography, the preprocessing of topographic elevation data and extraction algorithm of topographic feature are proposed, and the corresponding extraction of topographic feature is done. A terrain risk assessment method is presented based on terrain roughness and slope information fusion, aiming at the problem that terrain roughness and gradient cannot be directly reflected from the terrain elevation data, in this paper. The innovation is that it is the first time that the bilinear interpolation algorithm is applied in preprocess of elevation data and extraction of topographic feature, as well as the terrain roughness and gradient information fusion algorithm are applied to terrain feature extraction and risk assessment for the first time. By simulation and checking calculation of a certain digital topography example, it is proved that the extraction method of topographic information based on elevation data is feasible and reliable. It will provide a new research approach for target information recognition and topography risk assessment accurately.

In this study, a cadmium-tolerant bacterium, Enterobacter ludwigii LY6, was isolated from cadmium-contaminated soil in Shifang, Sichuan province, China. The cadmium chloride removal rate of the strain LY6 with a treatment of 100 mg/L cadmium chloride reached 56.0%. Scanning electron microscopy showed that exopolysaccharides (EPS) might be the main means of cadmium adsorption by the strain. X-ray powder diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analyses indicated that cadmium sulfide nanoparticles formed on the surface of bacteria cultured in a medium containing 100 mg/L cadmium chloride. In addition, the expression of several genes increased with the increase of the cadmium concentration in the medium, including the multiple antibiotic resistance proteins marA and marR, and the cold shock protein CspA. GO functions, such as the redox activity, respiratory chain and transport functions, and KEGG pathways involved in “bacterial chemotaxis” and “terpenoid backbone biosynthesis” were found to be closely related to bacterial cadmium tolerance and biosorption. This is the first report that E. ludwigii can reduce sulfate to form cadmium sulfide nanoparticles under high concentration cadmium exposure. The genes related to cadmium tolerance identified in this study lay a foundation for the genetic breeding of cadmium-tolerant strains.

Dispersive liquid-liquid microextraction is a new sample pretreatment technology based on traditional liquid liquid extraction. In this paper, the application of low-toxicity extractants such as low-density extractants, auxiliary extractants, stripping agents and ionic liquids in this technology and the extraction modes such as solvent de-emulsification, suspension extractant curing, auxiliary extraction, back extraction, and ionic liquid-dispersion liquid microextraction, are summarized. In addition, the synergism of this technique with other sample preparation techniques, such as liquid-liquid extraction, solid-phase extraction, solid-phase microextraction, dispersive solid phase extraction, matrix solid-phase dispersion extraction, supercritical fluid extraction and ultrasound-assisted dispersive liquid-liquid microextraction is discussed.