Nonlinear dynamics of planetary roller screw mechanism.

The synchronous meshing of the gear pair and the screw pair is a typical feature of the planetary roller screw mechanism. In order to fully derive and analyze the nonlinear dynamic characteristics of the system, this paper creatively incorporates the time-varying meshing stiffness of gear pair and the comprehensive transmission error into the research content. Combined with the thread contact force and friction force between the roller and the screw and between the roller and the nut, the nonlinear dynamic model of the planetary roller screw mechanism considering the meshing excitation of the gear pair is established. According to the time domain diagram, frequency domain diagram, phase plane diagram, Poincaré section diagram, three-dimensional spectrum diagram, and spatial phase diagram, the nonlinear behavior of the system is described in detail, and the bifurcation evolution process of the system under the excitation frequency parameters of the external load is revealed. In addition, based on the theory of multi-scale method and considering the variables such as meshing stiffness, meshing damping, and load fluctuation, the stability equation of the primary resonance of the system is derived. The analysis of the stability of the system under different working conditions shows that the parameters are selected within a reasonable range, which effectively reduces the primary common amplitude value and enhances the overall stability of the system. The research content improves the previous system dynamics modeling method and provides a theoretical basis for the nonlinear dynamics modeling method and parameter optimization design of the planetary roller screw mechanism.

Simulation of the Service Environment and Selection of the Refractory Lining for a Heat Recovery Coke Oven.

A heat recovery coke oven (HRCO) is one of important approaches to achieving a carbon peak and carbon neutrality in China. However, the steady operation of an HRCO is significantly influenced by the internal working conditions and the quality of lining refractories. In this work, a comprehensive study of the internal working conditions of an HRCO was carried out. The results suggest that the partition wall (PW) between the carbonization and combustion chambers is the most vulnerable area, with the corresponding traditional silica bricks inadequate for the service requirements. A reference based on a comparison of the average thermal stress and high-temperature compressive strength is offered for evaluating and selecting silica bricks for the PW. New optimized silica bricks within the reference are verified to be more applicable to the actual working conditions of an HRCO than the traditional silica bricks. As such, this work provides valuable guidance for the optimization and selection of silica bricks for the PW in an HRCO.

Canalicular laceration repair using a novel bicanalicular silicone stent versus traditional bicanalicular stent with nasal fixation.

PURPOSE: To compare the clinical effects of two types of lacrimal stents in the repair of canalicular lacerations. METHODS: A retrospective analysis was conducted on patients with canalicular lacerations between January 2017 and December 2022. The canalicular reconstruction was performed using either the Runshi-RS bicanalicular silicone stent or the traditional bicanalicular silicone stent with nasal fixation, under a surgical microscope. The stent was placed for 3 months, and patients were followed up for more than 3 months after extubation. The anatomical and functional success rates were compared between the two groups. Anatomical success was assessed through diagnostic probing and irrigation of lacrimal passage, while functional success was determined by the patient's subjective symptoms of epiphora. RESULTS: The study included 315 patients (315 eyes) undergoing canalicular laceration repair. The Runshi-RS stent was utilized in 147 patients (46.7%), while the traditional stent with nasal fixation was employed in 168 patients (53.3%). The anatomical success rates (99.3% vs 98.8%, P = 0.642) and functional success rates (87.2% vs 88.1%, P = 0.926) were similar between the RS group and the traditional stent group. Postoperative complications were fewer (4.1% vs 10.1%, P = 0.04) and the operation time was shorter (67.1 ± 35.3 min vs 86.1 ± 43.4 min, P < 0.001) in the RS group. CONCLUSION: The Runshi-RS tube demonstrates favorable surgical outcomes for the repair of canalicular lacerations. Compared to the traditional stent with nasal fixation, the RS stent allows for shorter operation times and fewer postoperative complications in the repair of canalicular lacerations.

A Measurement Solution of Face Gears with 3D Optical Scanning.

Gears are usually measured by the contact metrology method in gear measuring centers or coordinate measuring machines. Recently, three-dimensional (3D) optical scanning, a non-contact metrology method, has been applied in the industry as an advanced measurement technology mainly due to its high efficiency. However, its applications to gears with complicated geometry, such as face gears, are still limited due to its relatively low accuracy and the void of related measurement solutions. In this work, an accurate measurement solution with 3D optical scanning is proposed for the tooth surface deviations of orthogonal face gears. First, point cloud collection is carried out by the 3D scanner. Furthermore, the measurement solution is implemented with a three-stage algorithm by aligning point clouds with the design model. Subsequently, 3D modeling is studied by numbering the points and reconstructing the real tooth surfaces. An example with a measurement experiment and loaded tooth contact analysis is given to show the validity of the proposed method.

Hyperbolic odorant mixtures as a basis for more efficient signaling between flowering plants and bees.

Animals use odors in many natural contexts, for example, for finding mates or food, or signaling danger. Most analyses of natural odors search for either the most meaningful components of a natural odor mixture, or they use linear metrics to analyze the mixture compositions. However, we have recently shown that the physical space for complex mixtures is 'hyperbolic', meaning that there are certain combinations of variables that have a disproportionately large impact on perception and that these variables have specific interpretations in terms of metabolic processes taking place inside the flower and fruit that produce the odors. Here we show that the statistics of odorants and odorant mixtures produced by inflorescences (Brassica rapa) are also better described with a hyperbolic rather than a linear metric, and that combinations of odorants in the hyperbolic space are better predictors of the nectar and pollen resources sought by bee pollinators than the standard Euclidian combinations. We also show that honey bee and bumble bee antennae can detect most components of the B. rapa odor space that we tested, and the strength of responses correlates with positions of odorants in the hyperbolic space. In sum, a hyperbolic representation can be used to guide investigation of how information is represented at different levels of processing in the CNS.

Using Global t-SNE to Preserve Intercluster Data Structure.

The t-distributed stochastic neighbor embedding (t-SNE) method is one of the leading techniques for data visualization and clustering. This method finds lower-dimensional embedding of data points while minimizing distortions in distances between neighboring data points. By construction, t-SNE discards information about large-scale structure of the data. We show that adding a global cost function to the t-SNE cost function makes it possible to cluster the data while preserving global intercluster data structure. We test the new global t-SNE (g-SNE) method on one synthetic and two real data sets on flower shapes and human brain cells. We find that significant and meaningful global structure exists in both the plant and human brain data sets. In all cases, g-SNE outperforms t-SNE and UMAP in preserving the global structure. Topological analysis of the clustering result makes it possible to find an appropriate trade-off of data distribution across scales. We find differences in how data are distributed across scales between the two subjects that were part of the human brain data set. Thus, by striving to produce both accurate clustering and positioning between clusters, the g-SNE method can identify new aspects of data organization across scales.

Pretarsal orbicularis oculi muscle tightening with skin flap excision in the treatment of lower eyelid involutional entropion.

BACKGROUND: To evaluate a modified technique for involutional entropion correction in a retrospective cohort study. METHODS: The patients with involutional entropion eyelid were corrected by tightening the pretarsal orbicularis oculi muscle and excising the excess skin of the lower eyelid. The patients received correction surgery from April 2013 to March 2019 were followed up for more than 6 months postoperatively. The outcome measures included the complications and the recurrence rates. RESULTS: Total 152 patients (169 eyes) were included. The mean follow-up period was 29.6 months (range: 6-36 months). Postoperative ectropion (over-correction) was observed in 1 patient with 1 eyelid (0.59%); yet, no further surgery was needed for this patient. Recurrence of entropion was found in 1 patient (0.59%). The patient with recurrent entropion received repeated surgery with the same method and achieved a good eyelid position. CONCLUSIONS: This study demonstrated that tightening the pretarsal orbicularis oculi muscle and excising the excess skin of the lower eyelid could be an effective surgical method to correct lower eyelid involutional entropion. This method is technically easy with a low recurrence rate and not associated with significant complications in Asians.

An Efficient Approach to the Five-Axis Flank Milling of Non-Ferrous Spiral Bevel Gears.

Five-axis flank milling has been applied in industry as a relatively new method to cut spiral bevel gears (SBGs) for its flexibility, especially for the applications of small batches and repairs. However, it still has critical inferior aspects compared to the traditional manufacturing ways of SBGs: the efficiency is low, and the machining accuracy may not ensure the qualified meshing performances. To improve the efficiency, especially for cutting non-ferrous metals, this work proposes an approach to simultaneously cut the tooth surface and tooth bottom by a filleted cutter with only one pass. Meanwhile, the machining accuracy of the contact area is considered beforehand for the tool path optimization to ensure the meshing performances, which is further confirmed by FEM (finite element method). For the convenience of the FEM, the tooth surface points are calculated with an even distribution, and the calculation process is efficiently implemented with a closed-form solution. Based on the proposed method, the number (or total length) of the tool path is reduced, and the contact area is qualified. Both the simulation and cutting experiment are implemented to validate the proposed method.

Hyperbolic geometry of gene expression.

Patterns of gene expressions play a key role in determining cell state. Although correlations in gene expressions have been well documented, most of the current methods treat them as independent variables. One way to take into account gene correlations is to find a low-dimensional curved geometry that describes variation in the data. Here we develop such a method and find that gene expression across multiple cell types exhibits a low-dimensional hyperbolic structure. When more genes are taken into account, hyperbolic effects become stronger but representation remains low dimensional. The size of the hyperbolic map, which indicates the hierarchical depth of the data, was the largest for human cells, the smallest for mouse embryonic cells, and intermediate in differentiated cells from different mouse organs. We also describe how hyperbolic metric can be incorporated into the t-SNE method to improve visualizations compared with leading methods.

Dynamical Electrical Complexity Is Reduced during Neuronal Differentiation in Autism Spectrum Disorder.

Neuronal activity can be modeled as a nonlinear dynamical system to yield measures of neuronal state and dysfunction. The electrical recordings of stem cell-derived neurons from individuals with autism spectrum disorder (ASD) and controls were analyzed using minimum embedding dimension (MED) analysis to characterize their dynamical complexity. MED analysis revealed a significant reduction in dynamical complexity in ASD neurons during differentiation, which was correlated to bursting and spike interval measures. MED was associated with clinical endpoints, such as nonverbal intelligence, and was correlated with 53 differentially expressed genes, which were overrepresented with ASD risk genes related to neurodevelopment, cell morphology, and cell migration. Spatiotemporal analysis also showed a prenatal temporal enrichment in cortical and deep brain structures. Together, we present dynamical analysis as a paradigm that can be used to distinguish disease-associated cellular electrophysiological and transcriptional signatures, while taking into account patient variability in neuropsychiatric disorders.

Simulations and error analysis of the CNC milling of a face gear tooth with given tool paths.

This data article gives the validation files to the article "CNC milling of face gears with a novel geometric analysis" [1]. The data is about the simulation and machining error analysis of the CNC milling of a face gear tooth with given tool paths. It includes four files. Three of them are simulation videos of the CNC milling process in VERICUT with a general view, partial view and enlarged view, respectively. The other one is the source file of the machining error analysis, and it has the design model of the face gear, the simulated machined model of the face gear, and machining error analysis according to the comparison of the design model and simulated machined model.

Hyperbolic geometry of the olfactory space.

In the natural environment, the sense of smell, or olfaction, serves to detect toxins and judge nutritional content by taking advantage of the associations between compounds as they are created in biochemical reactions. This suggests that the nervous system can classify odors based on statistics of their co-occurrence within natural mixtures rather than from the chemical structures of the ligands themselves. We show that this statistical perspective makes it possible to map odors to points in a hyperbolic space. Hyperbolic coordinates have a long but often underappreciated history of relevance to biology. For example, these coordinates approximate the distance between species computed along dendrograms and, more generally, between points within hierarchical tree-like networks. We find that both natural odors and human perceptual descriptions of smells can be described using a three-dimensional hyperbolic space. This match in geometries can avoid distortions that would otherwise arise when mapping odors to perception.

Mantle cell lymphoma in a lacrimal gland in a female and a review of the literature.

PURPOSE: To report a rare case of Mantle cell lymphoma in lacrimal gland and review of the literature CASE REPORT: We report a case of a 59-year-old female who presented with an upper eyelid mass in the right eye for 3 months, without pain and irrigation. A computerized tomography (CT) scan showed a mass in the bilateral lacrimal gland region, more significant in right eye. The patient underwent a lacrimal gland mass excision surgery and diagnosis of mantle cell lymphoma by histopathology. Immunochemistry for CD20, CD79a, CD5, and CyclinD1 was positive. She was recommended to the Shantou cancer hospital for chemotherapy. CONCLUSION: Mantle cell lymphoma is a rare type of malignant lymphoma, over expressing CD5 and cyclin D1 antigens, which distinguishes it from other B cell lymphomas.